Effects of Maternal and Infant Characteristics on Birth Weight and Gestation Length in a Colony of Rhesus Macaques (Macaca mulatta)

A retrospective study using maternal and birth statistics from an open, captive rhesus macaque colony was done to determine the effects of parity, exposure to simian retrovirus (SRV), housing, maternal parity, and maternal birth weight on infant birth weight, viability and gestation length. Retrospective colony statistics for a 23-y period indicated that birth weight, but not gestation length, differed between genders. Adjusted mean birth weights were higher in nonviable infants. Mothers positive for SRV had shorter gestations, but SRV exposure did not affect neonatal birth weights or viability. Infants born in cages had longer gestations than did those born in pens, but neither birth weight nor viability differed between these groups. Maternal birth weight did not correlate with infant birth weight but positively correlated with gestation length. Parity was correlated with birth weight and decreased viability. Increased parity of the mother was associated with higher birth weight of the infant. A transgenerational trend toward increasing birth weight was noted. The birth statistics of this colony were consistent with those of other macaque colonies. Unlike findings for humans, maternal birth weight had little predictive value for infant outcomes in rhesus macaques. Nonviable rhesus infants had higher birth weights, unlike their human counterparts, perhaps due to gestational diabetes occurring in a sedentary caged population. Similar to the situation for humans, multiparity had a protective effect on infant viability in rhesus macaques.Abbreviations: ANCOVA, analysis of covariance; PRL, Primate Research Laboratory; SRV, simian retrovirusThe rhesus macaque (Macaca mulatta) is a useful animal model for human female reproduction studies because the comparative physiology between the 2 species is nearly identical.^1.5,49 Some factors that affect birth weight and neonatal viability in both humans and macaques include maternal birth weight, maternal age, maternal parity, and the presence of underlying maternal disease. Even experimentally induced simulated human lifestyle factors can affect neonatal outcome.^{10,16,17,25,44}In humans, maternal birth weight correlates with infant birth weight such that low birth weight mothers themselves have low birth weight infants.^8,19,28,30 A similar association has been shown in the macaque.^38,39 Because low birth weight is associated with increased neonatal mortality in humans and in macaques, this correlation, if present, may have important predictive value.^{11,20,21,32,45,47,53} One objective of this study was to establish whether maternal birth weight correlated with neonatal birth weight and viability in this colony of rhesus macaques.The relationship between parity, age, and birth outcomes in humans is controversial because multiparous and grand multiparous women tend to be of lower socioeconomic status, older, and have many confounding lifestyle factors.^2,24,27,56 In macaques, low parity and young age are associated with reproductive failure.⁵⁰ In pigtailed macaques (Macaca nemestrina), increased parity was associated with decreased neonatal viability but increased birth weight. Despite their lower parity, younger mothers in the colony of pigtailed macaques produced lower birth-weight infants, but more viable infants, compared with those of older mothers.¹⁷ The positive correlation between birth weight and viability merits further investigation in rhesus macaques. One objective of the current study was to determine whether maternal parity and age affected birth weight and neonatal viability in our rhesus macaque colony.The lifestyle factors of alcohol consumption, cigarettes, caffeine, drug use, diabetes and exercise have all been shown to influence birth weight and gestation length in humans and macaques.^{4,7,15,22,26,35,40,42,44,51,55} Captive animals can become obese and develop insulin-resistant diabetes, which prolongs gestation and produces oversized infants that are less healthy.^21,46,51 Because exercise is a preventative lifestyle factor for obesity and diabetes, it would be useful to compare active animals with sedentary ones.³⁰ Previous retrospective colony studies in pigtail macaques show that cage type, location, and social housing have significant effects on birth weight and birth outcome.^18,19 Another objective of the current study was to determine whether housing in cages (sedentary animals) or group pens (active animals) influenced gestation length, birth weight, and viability in our rhesus macaques.Another factor in birth outcome is the disease status of the mother. Viral infections, particularly of adenoviruses and immunosuppressive retroviruses, are associated with low birth weight and infant mortality in humans and nonhuman primates.^{13,21,25,33, 34,52,53} A previous report describes maternal transmission of simian retrovirus in a colony of pigtailed macaques with concurrent immunosuppression, low birth weight, and increased infant mortality in viremic mothers.³³ However, some evidence suggests that lentiviral antibodies in amniotic fluid may protect against in utero infection.²³ Further confounding the effects of retroviruses on reproductive outcome, animals infected horizontally can be viremic but serologically negative, and animals with sufficient, detectable immune responses may have provirus latent in their tissues.³³ Because simian retrovirus (SRV) was endemic in the subject rhesus colony and most data were retrospective thus preventing confirmation of viremia, another objective was to determine whether seropositivity of the dam was associated with neonatal viability, gestation length, and infant birth weight.     

Hypertrophic Cardiomyopathy in Owl Monkeys (Aotus spp.)

Cardiac hypertrophy is a common postmortem finding in owl monkeys. In most cases the animals do not exhibit clinical signs until the disease is advanced, making antemortem diagnosis of subclinical disease difficult and treatment unrewarding. We obtained echocardiograms, electrocardiograms, and thoracic radiographs from members of a colony of owl monkeys that previously was identified as showing a 40% incidence of gross myocardial hypertrophy at necropsy, to assess the usefulness of these modalities for antemortem diagnosis. No single modality was sufficiently sensitive and specific to detect all monkeys with cardiac hypertrophy. Electrocardiography was the least sensitive method for detecting owl monkeys with hypertrophic cardiomyopathy. Thoracic radiographs were more sensitive than was electrocardiography in this context but cannot detect animals with concentric hypertrophy without an enlarged cardiac silhouette. Echocardiography was the most sensitive method for identifying cardiac hypertrophy in owl monkeys. The most useful parameters suggestive of left ventricular hypertrophy in our owl monkeys were an increased average left ventricular wall thickness to chamber radius ratio and an increased calculated left ventricular myocardial mass. Parameters suggestive of dilative cardiomyopathy were an increased average left ventricular myocardial mass and a decreased average ratio of left ventricular free wall thickness to left ventricular chamber radius. When all 4 noninvasive diagnostic modalities (physical examination, echocardiography, electrocardiography, and thoracic radiography) were used concurrently, the probability of detecting hypertrophic cardiomyopathy in owl monkeys was increased greatly.Abbreviations: LVFWTd, left ventricular free wall thickness at end-diastole; STd, interventricular septal thickness at end-diastole; EDD, left ventricular chamber diameter at end-diastole; ESD, left ventricular chamber diameter at end-systole; VHS, vertebral heart scaleOwl monkeys (Aotus spp.) are maintained and used primarily as a nonhuman primate model for the study of malaria.^17,38,45 These neotropical monkeys have also been shown to be useful for the study of visceral leishmaniasis,⁵ various viruses,^1,20-22,27 streptotrichosis,¹⁹ campylobacteriosis,¹⁶ and toxoplasmosis.³⁴ Owl monkeys are naturally susceptible to a variety of internal parasites,^37,39 hemolytic anemia, and glomerulonephritis.^8,13,40Approximately 40% of Aotus monkeys dying from all causes in a colony maintained for dispersement to investigators for the study of malaria have gross evidence of myocardial hypertrophy at necropsy.⁴⁰ This incidence is similar to the 41% mortality ascribed to cardiovascular disease in captive adult lowland gorillas,²⁵ and the report that, in humans, cardiovascular disease represents 42% of all deaths in the United States.⁹ The hypertrophy in owl monkeys almost obliterates the left ventricular chamber and causes marked thickening of the left ventricular free wall and interventricular septum. A similar incidence of myocardial hypertrophy has previously been reported in other owl monkey colonies.^13,31,32Most of the deaths in the owl monkey colony at our institution can be attributed to various identifiable causes typical for this species.⁴⁰ However, several monkeys in this colony had gross evidence of myocardial hypertrophy at death but had shown no clinical signs of disease and displayed no gross or microscopic etiology for death. A prominent feature of the spontaneous deaths within this particular colony of Aotus monkeys was ‘sudden death,’ particularly during periods of high physical and psychologic stress.⁴⁰ Ventricular arrhythmias have been hypothesized as possible cause of sudden death in chimpanzees with cardiomyopathy,¹⁰ and a similar mechanism might be responsible for sudden death in captive owl monkeys.Gross hypertrophy of the left ventricle has many causes in humans and animals. In the absence of gross evidence of resistive lesions (that is, coarctation of the aorta, aortic stenosis) or shunting lesions (that is, ventricular septal defect, patent ductus arteriosus, atrial septal defect), hypertrophic cardiomyopathy and hypertension are the 2 most likely causes of or stimulus for the left ventricular hypertrophy observed in our colony.^4,18 Because no gross lesions that contribute to myocardial hypertrophy have been found at necropsy, we presumed that the hypertrophic changes in our monkeys are due to hypertrophic cardiomyopathy or to increased afterload secondary to hypertension. Spontaneous hypertension has been reported as causing dilated cardiomyopathy in wooly monkeys,¹¹ and vitamin E deficiency is a cause of cardiomyopathy (primarily dilative) in gelada baboons as well as other primates.^23,24 Cardiac changes secondary to experimental trypanosomiasis have occurred in vervet²⁸ and squirrel monkeys²⁹ and after group A streptococcal infection in rhesus monkeys.²⁶ However, only a few reports detail spontaneous myocardial hypertrophic changes in nonhuman primates.^3,10,13,32 Because of the high incidence of cardiac hypertrophy in clinically normal owl monkeys, it is difficult to establish ‘normal’ reference values for the species. One group of authors³¹ was reluctant to suggest reference intervals for normal echocardiographic variables in owl monkeys due to inability to confirm that monkeys classified as normal were free of cardiac disease.The left ventricular hypertrophy in the owl monkey colony we present has been speculated to be the result of renal-induced hypertension. Many of these monkeys have evidence of glomerular lesions at necropsy. Spontaneous primary systemic hypertension has been suggested as the etiology of the cardiomyopathy and renal disease in owl monkeys,¹³ however, no relationship between antemortem blood pressure and the presence or absence of renal lesions and myocardial hypertrophy in these monkeys had been established until recently. A recent study³⁵ using chronically implanted pressure transducers in A. nancymae found that 30% of the monkeys had resting mean arterial pressures in the hypertensive range (>110 mm Hg), and all animals had exaggerated pressor responses in response to routine husbandry procedures (mean arterial pressure, 125 to 196 mm Hg). These same authors concluded that the hypertension observed was consistent with a neural-based essential hypertension that possibly was engendered by the frequent hyperreactive responses of the sympathetic nervous system of these animals to environmental events.³⁵This study was undertaken to identify individual owl monkeys with left ventricular hypertrophy by using noninvasive diagnostic techniques antemortem. Physical examination, echocardiography, electrocardiography, and thoracic radiography were selected as potential diagnostic modalities with the greatest probability of yielding sensitive and specific information regarding left ventricular hypertrophy in individual monkeys prior to postmortem examination.     

Treatment of Giardiasis in Common Marmosets (Callithrix jacchus) with Tinidazole

Giardia intestinalis is a common protozoan parasite that can infect many laboratory animal primates, although its role as a contributor to the induction of gastrointestinal disease remains unclear. This study sought to investigate the prevalence of Giardia in a colony of common marmosets by using a Giardia antigen-capture assay and to address the possible eradication of this infection by using tinidazole, an antiprotozoal similar to metronidazole but requiring fewer doses. Among 31 colony marmosets, 13 (42%) were positive for Giardia. Two doses of oral tinidazole eliminated the infection in all animals. Repeat testing of the 13 Giardia-positive monkeys 1 y later showed that 11 remained negative and that treated animals had a significant increase in weight at 1 y. Giardia antigen is common in common marmoset feces, and treatment using oral tinidazole is possible and highly effective.Giardia intestinalis is a common zoonotic protozoan parasite causing diarrhea in humans and animals worldwide. Infection usually results from contact with the feces of an infected host or drinking water contaminated with Giardia cysts. As few as 10 cysts are necessary for infection in human subjects.³⁶ Giardia causes both an acute disease and a chronic asymptomatic state. The most common clinical signs of acute disease are diarrhea, flatulence, foul stool, and abdominal cramps. In addition, Giardia has been implicated as a cause of cognitive impairment and stunted growth in infected children in developing countries.^1,2,29Giardiasis has previously been reported to occur in a variety of laboratory primates, including several species of neotropical monkeys such as marmosets and squirrel monkeys.^13,20,28 Such infections may pose a zoonotic risk to animal handlers and potentially affect colony health. Common marmosets (Callithrix jacchus) frequently manifest chronic wasting and inflammatory bowel disease known as ‘wasting marmoset syndrome.’ The etiology of the intestinal disease is unknown, but marmosets often present clinically with skeletal muscle atrophy, marked weight loss, alopecia, and a history of intermittent diarrhea.^{5,11,16,21,35} Likely no single infectious agent or nutritional deficiency causes the clinical spectrum, but rather a combination of factors result in antigenic stimulation of the intestinal tract resulting in the chronic disease. The presence of Giardia cannot be ruled out as a cofactor.Several studies have compared various diagnostic tools for detection of Giardia in fecal specimens. Multiple fecal tests for Giardial colonization are available, including antigen-detection enzyme immunoassays, immunochromatographic strips, and microscopy of wet-mounted stool after fecal flotation.^9,24,37,38 Enzyme immunoassays are a rapid and precise tool for detecting Giardia in fecal specimens; test sensitivities and specificities have approached 100% in several studies.^9,22,24,37 In addition, these studies have indicated that repeat stool sampling on different days may increase the yield of testing, because organisms are variably shed.^9,14,36 The specific recommendation is to test 3 samples on alternate days or 3 samples within a 10-d span.³⁸Treatment options for Giardia infection are varied and include metronidazole, albendazole, quinacrine, furazolidone, and several other nitroimidazoles including tinidazole, secnidazole, ornidazole, and nimorazole.¹⁵ The most common treatment choice in veterinary medicine is metronidazole; however, this drug requires 5 to 8 d of treatment and ensuring animal compliance is difficult.²⁷ Several of metronidazole''s structural analogues, including tinidazole, are used as a single dose in the treatment of Giardiasis in humans with high cure rates (approximately 90%) and low complications.^3,8,10,26,39In this study we examined the use of a commercially available antigen-capture assay to diagnose Giardiasis in a large breeding colony of common marmosets. To address possible eradication of the infection, we describe the safe use and efficacy of tinidazole as a new treatment option in this species.     

Clinicopathologic Characteristics,Prevalence, and Risk Factors of Spontaneous Diabetes in Sooty Mangabeys (Cercocebus atys)

In 2008, clinical observations in our colony of sooty mangabeys (Cercocebus atys) suggested a high frequency of type 2 diabetes. Postmortem studies of diabetic animals revealed dense amyloid deposits in pancreatic islets. To investigate these findings, we screened our colony (97 male mangabeys; 99 female mangabeys) for the disease from 2008 to 2012. The overall prevalence of diabetes was 11% and of prediabetes was 7%, which is nearly double that reported for other primate species (less than 6%). Fructosamine and triglyceride levels were the best indicators of diabetes; total cholesterol and glycated hemoglobin were not associated with disease. Increasing age was a significant risk factor: prevalence increased from 0% in infants, juveniles, and young adults to 11% in adults and 19% in geriatric mangabeys. Sex, medroxyprogesterone acetate exposure, and SIV status were unrelated to disease. Weight was marginally higher in prediabetics, but body condition did not indicate obesity. Of the 49 mangabeys that were necropsied after clinical euthanasia or death from natural causes, 22 were diabetic; all 22 animals demonstrated pancreatic amyloid, and most had more than 75% of islets replaced with amyloid. We conclude that type 2 diabetes is more common in mangabeys than in other primate species. Diabetes in mangabeys has some unusual pathologic characteristics, including the absence of altered cholesterol levels and glycated hemoglobin but a robust association of pancreatic insular amyloidosis with clinical diabetes. Future research will examine the genetic basis of mangabey diabetes and evaluate additional diagnostic tools using imaging and serum markers.Abbreviations: HbA1c, glycated hemoglobin; MPA, medroxyprogesterone acetate; YNPRC, Yerkes National Primate Research CenterSooty mangabeys (Cercocebus atys) are Old World NHP that are native to West Africa. Historically their use in research has been limited to infectious disease studies, leprosy studies, and behavioral research.^14,25 Over the past 20 to 30 y, they have been used in HIV–AIDS research. Mangabeys are natural hosts of SIV_smm, which is recognized as the origin of HIV2 infection in humans.^7,8,30,36,42 SIV typically is nonpathogenic in mangabeys despite high levels of virus replication, which makes this species a unique and invaluable model in AIDS research.^7,30,36,42 Our facility maintains a colony of approximately 200 sooty mangabeys. In 2008 clinical observations of relative hyperglycemia, glucosuria, and weight loss in our colony suggested that type 2 diabetes mellitus occurred at a relatively high frequency in this population. Spontaneous diabetes was found in 10% of the colony, and 5% of animals were prediabetic; this incidence is higher than that typically reported for other NHP species, such as cynomolgus macaques (less than 1% to 2%)²² and chimpanzees (less than 1%).³⁷ The prevalence of spontaneous diabetes in humans is typically 8.3%.^2,6,22,37 In addition, necropsies revealed that many affected animals had dense amyloid deposits in pancreatic islet cells. Insular amyloidosis was seen on histology, with a total replacement of islets by amyloid deposition in advanced diabetes. Advanced diabetes was determined by increased weight loss and severity of relative hyperglycemia. The increased clinical prevalence of diabetes in our mangabey colony prompted additional characterization of the clinicopathologic profile, risk factors, and prevalence of diabetes in our mangabey colony.The form of diabetes in this mangabey colony is characterized as type 2 diabetes mellitus, as they have hyperglycemia, hypertriglyceridemia, and islet amyloidosis. Type 2 diabetes mellitus is the most common of the 3 forms of diabetes, and has been documented in humans and NHP,^22,31,37,55 including rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis), Celebes crested macaques (Macaca nigra), bonnet macaques (Macaca radiate), pigtailed macaques (Macaca nemestrina), vervet monkeys (Chlorocebus pygerythrus), squirrel monkeys (Saimiri sciureus), chimpanzees (Pan troglodytes), and woolly monkeys (Lagothrix spp.).^{1,24,31,52,55} Type 2 diabetes is a chronic metabolic disorder in which insulin resistance occurs in liver, muscle, and adipose tissue. As type 2 diabetes progresses, it also can be characterized as a relative insulin deficiency.^{1,6,15,22,29,31,37,55} The initial clinical presentation of diabetes in humans and NHP includes polydipsia, polyuria, polyphagia, weight loss, and lethargy.^{1,6,22,27,31,37,55} Similar presentation was observed in our colony of diabetic mangabeys.Diagnostic criteria of diabetes in NHP species is similar to that for humans and is based on clinical symptoms and routine lab tests, including serum chemistry panel to evaluate persistent fasting hyperglycemia, hypertriglyceridemia, and hypercholesterolemia.^{2,6,11,16-18,21,22,29,31,37,48-50,52,55} Hypertriglyceridemia and hypercholesterolemia frequently are elevated due to diabetes and therefore are used as supportive diagnostic markers. In addition, the disease is characterized by transient hyperinsulinemia followed by insulin deficiency subsequent to glucose challenge. Urinalysis is used to evaluate glucosuria and ketonuria. These tests are not exclusive for diagnosing diabetes and can be inconsistent between species, thus making conclusive diagnosis challenging. For example, hyperglycemia can be a transient finding associated with recent food intake or stress associated with restraint for blood sample collection or anesthetic access, whereas hypertriglyceridemia can be seen in obese animals and those with other metabolic diseases such as pancreatitis and hypothyroidism.^1,22,37,55The typical clinical approach to the diagnosis of diabetes in NHP and other veterinary patients includes evaluation of fructosamine and glycated hemoglobin (HbA1c) levels and glucose tolerance testing. These tests are indices of glycemic control and are used in clinical settings primarily to assess prognosis and response to treatment; they are also useful for the initial diagnosis of diabetes when used in parallel with serum chemistry markers. Fructosamine and HbA1c can both provide information on long-term glycemic control, because fructosamine reflects average blood glucose levels over 2 to 3 wk whereas HbA1c reflects average blood glucose over 2 to 3 mo preceding blood collection. HbA1c is the primary test for diabetes in human medicine,^6,31,35,37 whereas fructosamine is commonly used in veterinary medicine. Glucose tolerance testing provides an indirect measure of insulin sensitivity, but it is not frequently used clinically in NHP because of the requirement for prolonged physical restraint or sedation.^{1,21,22,26,27,34,37,55}Prevention and management of diabetes in NHP and humans can be achieved by identifying potential risk factors, including age, weight, sex, genetics, hormone drug exposure, and viral status.^{1,6,15,22,29,31,37,42,55} Advanced age, obesity, sex, and genetics are associated with diabetes in some species of NHP and humans.^{1,6,15,22,29,31,37,55} In addition, exposure to drugs such as medroxyprogesterone acetate (MPA) is suspected to be linked to diabetes due to the hormonal effects of progesterone impacting glucoregulatory function.^{1,6,10,22,23,31,34,55} MPA exposure is of interest, because it is used regularly in our mangabey colony as both a contraceptive and as therapy for endometriosis. In addition, SIV status is being evaluated as a risk factor, because a portion of our colony is SIV positive. Although HIV is not thought to be associated with diabetes in people, SIV pathogenesis in mangabeys differs; therefore it was of interest to explore the possible association of SIV and diabetes in mangabeys.^7,30,36,42 Pancreatic insular amyloidosis has been documented to be associated with type 2 diabetes in several species. Amyloidosis is a group of disorders that are caused by extracellular deposition of misfolded proteins that can result in impaired function of any organ.^{15,20,23,28,32,43,45,48,49} Because a high incidence of pancreatic insular amyloid was noted at necropsy, we sought to document the relationship with clinical diabetes in mangabeys.Spontaneous type 2 diabetes mellitus has been well documented in several species of NHP. Because the literature contains little information regarding the clinicopathologic features (the ‘profile’), risk factors, and prevalence of spontaneous diabetes mellitus in sooty mangabeys, the primary aims of the current study were 1) to determine whether elevated levels of fasting blood glucose, fructosamine, HbA1c, triglycerides, and total cholesterol levels are reliable diagnostic markers of type 2 diabetes mellitus in this NHP species; 2) to determine whether age, sex, MPA exposure, and SIV status influence the risk of diabetes; 3) to determine whether body weight influences diabetic status; 4) to evaluate the relationship between pancreatic amyloidosis and diabetes mellitus; and 5) to characterize the prevalence of diabetes mellitus in the mangabey population at our institution. To our knowledge, this report is the first to describe the natural occurrence of type 2 diabetes mellitus within a captive colony of sooty mangabeys. We hypothesized that blood glucose, fructosamine, HbA1c, triglyceride, and total cholesterol would be reliable diagnostic markers and that age, sex, and MPA exposure would influence the risk of diabetes in this species.     

Role of Retinoic Acid and Fibroblast Growth Factor 2 in Neural Differentiation from Cynomolgus Monkey (Macaca fascicularis) Embryonic Stem Cells

Retinoic acid is a widely used factor in both mouse and human embryonic stem cells. It suppresses differentiation to mesoderm and enhances differentiation to ectoderm. Fibroblast growth factor 2 (FGF2) is widely used to induce differentiation to neurons in mice, yet in primates, including humans, it maintains embryonic stem cells in the undifferentiated state. In this study, we established an FGF2 low-dose-dependent embryonic stem cell line from cynomolgus monkeys and then analyzed neural differentiation in cultures supplemented with retinoic acid and FGF2. When only retinoic acid was added to culture, neurons differentiated from FGF2 low-dose-dependent embryonic stem cells. When both retinoic acid and FGF2 were added, neurons and astrocytes differentiated from the same embryonic stem cell line. Thus, retinoic acid promotes the differentiation from embryonic stem cells to neuroectoderm. Although FGF2 seems to promote self-renewal in stem cells, its effects on the differentiation of stem cells are influenced by the presence or absence of supplemental retinoic acid.Abbreviations: EB, embryoid body; ES, embryonic stem; ESM, embryonic stem cell medium; FGF, fibroblast growth factor; GFAP, glial fibrillary acidic protein; LIF, leukemia inhibitory factor; MBP, myelin basic protein; RA, retinoic acid; SSEA, stage-specific embryonic antigen; TRA, tumor-related antigenPluripotent stem cells are potential sources of material for cell replacement therapy and are useful experimental tools for in vitro models of human disease and drug screening. Embryonic stem (ES) cells are capable of extensive proliferation and multilineage differentiation, and thus ES-derived cells are suitable for use in cell-replacement therapies.^18,23 Reported ES cell characteristics including tumorigenic potential, DNA methylation status, expression of imprinted genes, and chromatin structure were elucidated by using induced pluripotent stem cells.^2,11,17 Because the social expectations of regeneration medicine are growing, we must perform basic research with ES cells, which differ from induced pluripotent stem cells in terms of origin, differentiation ability, and epigenetic status.^2,8Several advances in research have been made by using mouse ES cells. Furthermore, primate ES cell lines have been established from rhesus monkeys (Macaca mulatta),²⁴ common marmosets (Callithrix jacchus),²⁵ cynomolgus monkeys (M. fascicularis),²⁰ and African green monkeys (Chlorocebus aethiops).¹⁹ Mouse and other mammalian ES cells differ markedly in their responses to the signaling pathways that support self-renewal.^8,28 Mouse ES cells require leukemia inhibitory factor (LIF)–STAT3 signaling.¹⁴ In contrast, primate ES cells do not respond to LIF. Fibroblast growth factor 2 (FGF2) appears to be the most upstream self-renewal factor in primate ES cells. FGF2 also exerts its effects through indirect mechanisms, such as the TGFβ–Activin–Nodal signaling pathway, in primate ES cells.²¹ In addition to the biologic similarities between monkeys and humans, ES cells derived from cynomolgus monkeys or human blastocysts have extensive similarities that are not apparent in mouse ES cells.^8,14,21,28 Numerous monkey ES cell lines are now available, and cynomolgus monkeys are an efficient model for developing strategies to investigate the efficacy of ES-cell–based medical treatments in humans.Several growth factors and chemical compounds, including retinoic acid (RA),^4,9,13,22,26 FGF2,^9,10,16,22 epidermal growth factor,^9,22 SB431542,^1,4,10 dorsomorphin,^10,27 sonic hedgehog,^{12,13,16,27,29} and noggin,^1,4,9,27 are essential for the differentiation and proliferation or maintenance of neural stem cells derived from primate ES cells. Of these factors, active RA signaling suppresses a mesodermal fate by inhibiting Wnt and Nodal signaling pathways during in vitro culture and leads to neuroectoderm differentiation in ES cells.^4,13,26 RA is an indispensable factor for the specialization to neural cells. FGF2 is important during nervous system development,¹² and FGF2 and RA both are believed to influence the differentiation to neural cells. The current study was done to clarify the mechanism of RA and FGF2 in the induction of differentiation along the neural lineage.We recently established a monkey ES cell line that does not need FGF2 supplementation for maintenance of the undifferentiated state. This ES cell line allowed us to study the role of differentiation to neural cells with RA and enabled us to compare ES cell differentiation in the context of supplementation with RA or FGF2 in culture. To this end, we established a novel cynomolgus monkey cell line derived from ES cells and maintained it in an undifferentiated state in the absence of FGF2 supplementation.     

New-Onset Diabetes Mellitus After Transplantation in a Cynomolgus Macaque (Macaca fasicularis)

A 5.5-y-old intact male cynomolgus macaque (Macaca fasicularis) presented with inappetence and weight loss 57 d after heterotopic heart and thymus transplantation while receiving an immunosuppressant regimen consisting of tacrolimus, mycophenolate mofetil, and methylprednisolone to prevent graft rejection. A serum chemistry panel, a glycated hemoglobin test, and urinalysis performed at presentation revealed elevated blood glucose and glycated hemoglobin (HbA1c) levels (727 mg/dL and 10.1%, respectively), glucosuria, and ketonuria. Diabetes mellitus was diagnosed, and insulin therapy was initiated immediately. The macaque was weaned off the immunosuppressive therapy as his clinical condition improved and stabilized. Approximately 74 d after discontinuation of the immunosuppressants, the blood glucose normalized, and the insulin therapy was stopped. The animal''s blood glucose and HbA1c values have remained within normal limits since this time. We suspect that our macaque experienced new-onset diabetes mellitus after transplantation, a condition that is commonly observed in human transplant patients but not well described in NHP. To our knowledge, this report represents the first documented case of new-onset diabetes mellitus after transplantation in a cynomolgus macaque.Abbreviations: NODAT, new-onset diabetes mellitus after transplantationNew-onset diabetes mellitus after transplantation (NODAT, formerly known as posttransplantation diabetes mellitus) is an important consequence of solid-organ transplantation in humans.^{7-10,15,17,19,21,25-28,31,33,34,37,38,42} A variety of risk factors have been identified including increased age, sex (male prevalence), elevated pretransplant fasting plasma glucose levels, and immunosuppressive therapy.^{7-10,15,17,19,21,25-28,31,33,34,37,38,42} The relationship between calcineurin inhibitors, such as tacrolimus and cyclosporin, and the development of NODAT is widely recognized in human medicine.^{7-10,15,17,19,21,25-28,31,33,34,37,38,42} Cynomolgus macaques (Macaca fasicularis) are a commonly used NHP model in organ transplantation research. Cases of natural and induced diabetes of cynomolgus monkeys have been described in the literature;^14,43,45 however, NODAT in a macaque model of solid-organ transplantation has not been reported previously to our knowledge.     

Alterations in Cytokines and Effects of Dexamethasone Immunosuppression during Subclinical Infections of Invasive Klebsiella pneumoniae with Hypermucoviscosity Phenotype in Rhesus (Macaca mulatta) and Cynomolgus (Macaca fascicularis) Macaques

Invasive Klebsiella pneumoniae with the hypermucoviscosity phenotype (HMV K. pneumoniae) is an emerging human pathogen that also has been attributed to fatal multisystemic disease in African green monkeys at our institution. Combining a cluster of subclinically infected macaques identified in March and April 2008 and the animals documented during a subsequent survey of more than 300 colony nonhuman primates yielded a total of 9 rhesus macaques and 6 cynomolgus macaques that were subclinically infected. In an attempt to propagate the responsible HMV K. pneumoniae strain, a subset of these animals was immunosuppressed with dexamethasone. None of the treated animals developed clinical disease consistent with the multisystemic disease that affected colony African green monkeys. However, cytokine analysis revealed significant alterations of secreted cytokines in macaques subclinically infected with HMV K. pneumoniae when compared with noninfected macaques, thereby calling into question the suitability of animals subclinically infected with HMV K. pneumoniae for use in immunologic or infectious disease research.Abbreviations: HMV, hypermucoviscosity phenotype; rmpA, regulator of the mucoid phenotype gene; magA, mucoviscosity-associated geneKlebsiella pneumoniae is a gram-negative member of the Enterobacteriaceae family that comprises part of the normal fecal and oral flora of many nonhuman primates¹⁹ but also has been implicated in cases of peritonitis, septicemia, pneumonia, and meningitis in both Old and New World primates.^17,20,37 Over the past 20 y, strains of invasive K. pneumoniae with a unique hypermucoviscosity phenotype (HMV K. pneumoniae) have been reported to cause community-acquired primary liver abscesses, meningitis, and endophthalmitis in humans in Taiwan and other Asian countries,^{10, 26–31,33,44,48,51} mostly in people with diabetes mellitus.^7,8,44 In addition, HMV K. pneumoniae has caused clinical disease in the United States and other nonAsian countries.^18,30,33 The HMV phenotype is determined based on a positive string test, which is performed by touching a colony with a bacterial loop and gently lifting. If a mucoid ‘string’ of at least 5 mm forms, the string test is considered positive.^3,14,45,51Capsular serotypes K1 and K2 have been reported as the major virulence determinants for human HMV K. pneumoniae liver abscesses.^9,15,49,50 The products of the mucoviscosity-associated gene (magA), which encodes a structural outer membrane protein of the K1 serotype, and the regulator of the mucoid phenotype gene (rmpA) have also been proposed as virulence factors.^{16,34,42,52,53}HMV K. pneumoniae has been reported to cause multisystemic abscesses in African green monkeys (Chlorocebus aethiops).⁴⁵ In late 2005 and early 2006, 7 African green monkeys in the research colony at our institution, the US Army Medical Research Institute for Infectious Diseases, were found to have abscesses in multiple locations; all 7 animals either succumbed or were euthanized because of poor prognosis due to surgically nonresectable abdominal abscesses.⁴⁵ The etiology of the final case was determined to be HMV K. pneumoniae with the K2 serotype and rmpA, and all 6 other cases had similar clinical, microbiologic, and pathologic characteristics. Prior to the current study, we believe these 7 cases were the only documented natural infections attributed specifically to HMV K. pneumoniae in nonhuman primates.⁴⁵As a result of those findings, our institution instituted a policy to report K. pneumoniae positive cultures in nonhuman primates during quarantine periods and on routine semiannual examination. Over several months in spring and summer 2008, a group of 19 macaques tested positive on oropharyngeal or rectal culture for HMV K. pneumoniae; 15 of those 19 animals were isolated in a single room for 2 to 4 mo to better characterize the infection.³ None of the animals showed clinical signs of disease during the isolation period, and abdominal palpation failed to suggest the presence of abdominal abscesses like those seen in African green monkeys. Testing of isolates suggested that the macaques harbored subclinical infections and that multiple genotypes of HMV K. pneumoniae were present.³In July 2008, a cynomolgus macaque from the colony that was experimentally challenged with monkeypox virus survived beyond the normal time-to-death window (12 to 16 d after infection). However, on day 22 after infection (6 to 10 d beyond this window), this macaque died unexpectedly. Histopathologic analysis of tissues from this NHP revealed a concurrent gram-negative bacterial infection, based on Gram stains and immunohistochemistry. Although cultures were not available, PCR analysis of DNA extracted from formalin-fixed, paraffin-embedded tissues revealed the presence of K. pneumoniae through the amplification of rmpA,³⁹ which is consistent with the HMV phenotype. This animal was considered to have survived infection with monkeypox based on time to death after infection. Monkeypox is reported to target the mononuclear phagocyte system and associated dendritic cells,⁵⁴ and we theorized that the monkeypox infection in this macaque led to suppression of the immune system, which then allowed development of a fatal HMV K. pneumoniae septicemia.The present project sought to explore the pathophysiology of HMV K. pneumoniae in macaques. We hypothesized that immunosuppression of subclinically infected macaques would produce lesions similar to those observed in the coinfected macaque. In addition, we hypothesized that subclinically infected macaques would have a different immune profile from that of noninfected primates. We measured and analyzed cytokine levels as an indication of altered immune status because such a state potentially could confound research into immunologic responses and infectious disease.     

Induction of COX-2-PGE2 synthesis by activation of the MAPK/ERK pathway contributes to neuronal death triggered by TDP-43-depleted microglia

Neuroinflammation is a striking hallmark of amyotrophic lateral sclerosis (ALS) and other neurodegenerative disorders. Previous studies have shown the contribution of glial cells such as astrocytes in TDP-43-linked ALS. However, the role of microglia in TDP-43-mediated motor neuron degeneration remains poorly understood. In this study, we show that depletion of TDP-43 in microglia, but not in astrocytes, strikingly upregulates cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production through the activation of MAPK/ERK signaling and initiates neurotoxicity. Moreover, we find that administration of celecoxib, a specific COX-2 inhibitor, greatly diminishes the neurotoxicity triggered by TDP-43-depleted microglia. Taken together, our results reveal a previously unrecognized non-cell-autonomous mechanism in TDP-43-mediated neurodegeneration, identifying COX-2-PGE2 as the molecular events of microglia- but not astrocyte-initiated neurotoxicity and identifying celecoxib as a novel potential therapy for TDP-43-linked ALS and possibly other types of ALS.Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by the degeneration of motor neurons in the brain and spinal cord.¹ Most cases of ALS are sporadic, but 10% are familial. Familial ALS cases are associated with mutations in genes such as Cu/Zn superoxide dismutase 1 (SOD1), TAR DNA-binding protein 43 (TARDBP) and, most recently discovered, C9orf72. Currently, most available information obtained from ALS research is based on the study of SOD1, but new studies focusing on TARDBP and C9orf72 have come to the forefront of ALS research.^{1, 2} The discovery of the central role of the protein TDP-43, encoded by TARDBP, in ALS was a breakthrough in ALS research.^{3, 4, 5} Although pathogenic mutations of TDP-43 are genetically rare, abnormal TDP-43 function is thought to be associated with the majority of ALS cases.¹ TDP-43 was identified as a key component of the ubiquitin-positive inclusions in most ALS patients and also in other neurodegenerative diseases such as frontotemporal lobar degeneration,^{6, 7} Alzheimer''s disease (AD)^{8, 9} and Parkinson''s disease (PD).^{10, 11} TDP-43 is a multifunctional RNA binding protein, and loss-of-function of TDP-43 has been increasingly recognized as a key contributor in TDP-43-mediated pathogenesis.^{5, 12, 13, 14}Neuroinflammation, a striking and common hallmark involved in many neurodegenerative diseases, including ALS, is characterized by extensive activation of glial cells including microglia, astrocytes and oligodendrocytes.^{15, 16} Although numerous studies have focused on the intrinsic properties of motor neurons in ALS, a large amount of evidence showed that glial cells, such as astrocytes and microglia, could have critical roles in SOD1-mediated motor neuron degeneration and ALS progression,^{17, 18, 19, 20, 21, 22} indicating the importance of non-cell-autonomous toxicity in SOD1-mediated ALS pathogenesis.Very interestingly, a vital insight of neuroinflammation research in ALS was generated by the evidence that both the mRNA and protein levels of the pro-inflammatory enzyme cyclooxygenase-2 (COX-2) are upregulated in both transgenic mouse models and in human postmortem brain and spinal cord.^{23, 24, 25, 26, 27, 28, 29} The role of COX-2 neurotoxicity in ALS and other neurodegenerative disorders has been well explored.^{30, 31, 32} One of the key downstream products of COX-2, prostaglandin E2 (PGE2), can directly mediate COX-2 neurotoxicity both in vitro and in vivo.^{33, 34, 35, 36, 37} The levels of COX-2 expression and PGE2 production are controlled by multiple cell signaling pathways, including the mitogen-activated protein kinase (MAPK)/ERK pathway,^{38, 39, 40} and they have been found to be increased in neurodegenerative diseases including AD, PD and ALS.^{25, 28, 32, 41, 42, 43, 44, 45, 46} Importantly, COX-2 inhibitors such as celecoxib exhibited significant neuroprotective effects and prolonged survival or delayed disease onset in a SOD1-ALS transgenic mouse model through the downregulation of PGE2 release.²⁸Most recent studies have tried to elucidate the role of glial cells in neurotoxicity using TDP-43-ALS models, which are considered to be helpful for better understanding the disease mechanisms.^{47, 48, 49, 50, 51} Although the contribution of glial cells to TDP-43-mediated motor neuron degeneration is now well supported, this model does not fully suggest an astrocyte-based non-cell autonomous mechanism. For example, recent studies have shown that TDP-43-mutant astrocytes do not affect the survival of motor neurons,^{50, 51} indicating a previously unrecognized non-cell autonomous TDP-43 proteinopathy that associates with cell types other than astrocytes.Given that the role of glial cell types other than astrocytes in TDP-43-mediated neuroinflammation is still not fully understood, we aim to compare the contribution of microglia and astrocytes to neurotoxicity in a TDP-43 loss-of-function model. Here, we show that TDP-43 has a dominant role in promoting COX-2-PGE2 production through the MAPK/ERK pathway in primary cultured microglia, but not in primary cultured astrocytes. Our study suggests that overproduction of PGE2 in microglia is a novel molecular mechanism underlying neurotoxicity in TDP-43-linked ALS. Moreover, our data identify celecoxib as a new potential effective treatment of TDP-43-linked ALS and possibly other types of ALS.     

Serologic Evaluation of Clinical and Subclinical Secondary Hepatic Amyloidosis in Rhesus Macaques (Macaca mulatta)

Secondary hepatic amyloidosis in nonhuman primates carries a grave prognosis once animals become clinically ill. The purpose of this study was to establish serologic parameters that potentially could be used to identify rhesus macaques undergoing subclinical development of secondary hepatic amyloidosis. A retrospective analysis was completed by using serum biochemical profiles from 26 histologically diagnosed amyloidotic macaques evaluated at 2 stages of disease, clinical and subclinical (3 to 32 mo prior to clinical signs of disease). Standard serum biochemistry values for cases were compared with institutional age- and gender-specific references ranges by construction of 95% confidence intervals for the difference between means. In addition, 19 histologically diagnosed amyloidotic macaques and 19 age-matched controls were assayed for changes in various parameters by using routinely banked, frozen (–80 °C) sera available from clinical and subclinical time points. Clinically amyloidotic animals displayed increased levels of alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, gamma glutamyltranspeptidase, and macrophage colony-stimulating factor and significantly decreased quantities of albumin and total cholesterol. Subclinical amyloidotic animals displayed increased levels of alkaline phosphatase, aspartate aminotransferase, lactate dehydrogenase, and serum amyloid A and decreased concentrations of albumin and total cholesterol. The serologic parameters studied indicate a temporal relationship of these factors not previously described, show a clear pattern of disease progression, and could be useful in subclinical disease detection.Abbreviations: mCSF, macrophage colony stimulating factor; SAA, serum amyloid AAmyloid is an eosinophilic substance made of insoluble fibrillar protein.³² When deposited extracellularly, amyloid causes displacement of tissue form and disruption of organ function.³² Persistent accretion of amyloid can result in organ failure and ultimately animal death.²² Clinical signs of disease depend on the tissues affected and the degree of involvement.³² Amyloidosis has been well documented in humans, other mammals, birds, and reptiles.³⁸ In humans, amyloidosis plays a key role in many diseases, including Alzheimer disease, type II diabetes, rheumatoid arthritis, and Down syndrome.^15,20,35,38Amyloidosis generally is classified into 3 categories: primary, secondary, and hereditary. Primary amyloidosis consists of the immunoglobulin- and myeloma-associated types. Secondary (reactive) amyloidosis is associated with chronic inflammation.²⁴ Common causes of secondary amyloidosis in humans include rheumatoid arthritis, idiopathic colitis, infectious diseases, such as tuberculosis and leprosy, and malignant tumors, such as mesothelioma and Hodgkins disease.²⁸ Hereditary amyloid syndromes are rare and include Mediterranean fever, Muckle–Wells syndrome, and familial amyloid cardiomyopathy.^32,38Secondary amyloidosis is the most common form of amyloidosis in animals.³⁸ Amyloidosis occurs in many species of nonhuman primates including the common marmoset (Callithrix jacchus),²³ squirrel monkey (Saimiri sciureus),³⁴ rhesus macaque (Macaca mulatta),^9,10 pigtailed macaque (Macaca nemestrina),^18,27 crab-eating macaque (Macaca fascicularis),²⁷ barbary ape (Macaca sylvanus),⁶ baboon (Papio spp.),¹⁷ mandrill (Papio sphinx), and chimpanzee (Pan troglodytes).^16,39 Although a definitive cause of secondary amyloidosis has not been identified in nonhuman primates, this condition has been associated with chronic inflammation due to rheumatoid arthritis,⁶ viral infection,¹⁸ parasitism,¹ respiratory disease,^27,30 trauma,³⁰ and bacterial enterocolitis.^27,30,31 Shigella spp. have received particular attention as a common etiology linking enterocolitis with amyloidosis.^4,7,38Previous research on amyloidosis in nonhuman primates has yielded clinical and serologic profiles in end-stage amyloidotic animals, but little is known about the serologic status in the subclinical stages of disease. Amyloid can accumulate for as long as 3 y before severe organ disruption occurs¹⁴ and clinical signs of amyloidosis become evident.¹⁶ With appropriate analysis, detection of amyloidosis could occur much earlier than typically now achieved, thus allowing for targeted preventative therapy to potentially halt the progression of this insidious disease.     

Plasma membrane poration by opioid neuropeptides: a possible mechanism of pathological signal transduction

Neuropeptides induce signal transduction across the plasma membrane by acting through cell-surface receptors. The dynorphins, endogenous ligands for opioid receptors, are an exception; they also produce non-receptor-mediated effects causing pain and neurodegeneration. To understand non-receptor mechanism(s), we examined interactions of dynorphins with plasma membrane. Using fluorescence correlation spectroscopy and patch-clamp electrophysiology, we demonstrate that dynorphins accumulate in the membrane and induce a continuum of transient increases in ionic conductance. This phenomenon is consistent with stochastic formation of giant (~2.7 nm estimated diameter) unstructured non-ion-selective membrane pores. The potency of dynorphins to porate the plasma membrane correlates with their pathogenic effects in cellular and animal models. Membrane poration by dynorphins may represent a mechanism of pathological signal transduction. Persistent neuronal excitation by this mechanism may lead to profound neuropathological alterations, including neurodegeneration and cell death.Neuropeptides are the largest and most diverse family of neurotransmitters. They are released from axon terminals and dendrites, diffuse to pre- or postsynaptic neuronal structures and activate membrane G-protein-coupled receptors. Prodynorphin (PDYN)-derived opioid peptides including dynorphin A (Dyn A), dynorphin B (Dyn B) and big dynorphin (Big Dyn) consisting of Dyn A and Dyn B are endogenous ligands for the κ-opioid receptor. Acting through this receptor, dynorphins regulate processing of pain and emotions, memory acquisition and modulate reward induced by addictive substances.^{1, 2, 3, 4} Furthermore, dynorphins may produce robust cellular and behavioral effects that are not mediated through opioid receptors.^{5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29} As evident from pharmacological, morphological, genetic and human neuropathological studies, these effects are generally pathological, including cell death, neurodegeneration, neurological dysfunctions and chronic pain. Big Dyn is the most active pathogenic peptide, which is about 10- to 100-fold more potent than Dyn A, whereas Dyn B does not produce non-opioid effects.^{16, 17, 22, 25} Big Dyn enhances activity of acid-sensing ion channel-1a (ASIC1a) and potentiates ASIC1a-mediated cell death in nanomolar concentrations^{30, 31} and, when administered intrathecally, induces characteristic nociceptive behavior at femtomolar doses.^{17, 22} Inhibition of endogenous Big Dyn degradation results in pathological pain, whereas prodynorphin (Pdyn) knockout mice do not maintain neuropathic pain.^{22, 32} Big Dyn differs from its constituents Dyn A and Dyn B in its unique pattern of non-opioid memory-enhancing, locomotor- and anxiolytic-like effects.²⁵Pathological role of dynorphins is emphasized by the identification of PDYN missense mutations that cause profound neurodegeneration in the human brain underlying the SCA23 (spinocerebellar ataxia type 23), a very rare dominantly inherited neurodegenerative disorder.^{27, 33} Most PDYN mutations are located in the Big Dyn domain, demonstrating its critical role in neurodegeneration. PDYN mutations result in marked elevation in dynorphin levels and increase in its pathogenic non-opioid activity.^{27, 34} Dominant-negative pathogenic effects of dynorphins are not produced through opioid receptors.ASIC1a, glutamate NMDA (N-methyl-d-aspartate) and AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate ion channels, and melanocortin and bradykinin B2 receptors have all been implicated as non-opioid dynorphin targets.^{5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 30, 31, 35, 36} Multiplicity of these targets and their association with the cellular membrane suggest that their activation is a secondary event triggered by a primary interaction of dynorphins with the membrane. Dynorphins are among the most basic neuropeptides.^{37, 38} The basic nature is also a general property of anti-microbial peptides (AMPs) and amyloid peptides that act by inducing membrane perturbations, altering membrane curvature and causing pore formation that disrupts membrane-associated processes including ion fluxes across the membrane.³⁹ The similarity between dynorphins and these two peptide groups in overall charge and size suggests a similar mode of their interactions with membranes.In this study, we dissect the interactions of dynorphins with the cell membrane, the primary event in their non-receptor actions. Using fluorescence imaging, correlation spectroscopy and patch-clamp techniques, we demonstrate that dynorphin peptides accumulate in the plasma membrane in live cells and cause a profound transient increase in cell membrane conductance. Membrane poration by endogenous neuropeptides may represent a novel mechanism of signal transduction in the brain. This mechanism may underlie effects of dynorphins under pathological conditions including chronic pain and tissue injury.     

Endemic Viruses of Squirrel Monkeys (Saimiri spp.)

Nonhuman primates are the experimental animals of choice for the study of many human diseases. As such, it is important to understand that endemic viruses of primates can potentially affect the design, methods, and results of biomedical studies designed to model human disease. Here we review the viruses known to be endemic in squirrel monkeys (Saimiri spp.). The pathogenic potential of these viruses in squirrel monkeys that undergo experimental manipulation remains largely unexplored but may have implications regarding the use of squirrel monkeys in biomedical research.Abbreviations: HTLV1, human T-cell leukemia virus type 1; HVS, herpesvirus saimiri; IPF, idiopathic pulmonary fibrosis; SaHV, Saimiriine herpesvirus; SFV, simian foamy virus; SM-CMV, squirrel monkey cytomegalovirus; SMPyV, squirrel monkey polyomavirus; SMRV, squirrel monkey retrovirusThe similarity between the nonhuman primate and human immune systems is a key advantage in the use of nonhuman primates compared with other mammalian models of human disease.^{13,71,88,94,103,113,125} In addition, the diversity of environmental and infectious disease agents encountered by primates is similar to that of humans, providing nonhuman primates a comparable level of biologic complexity.¹ Old World primates, such as macaques and baboons, and New World primates, including squirrel monkeys and marmosets, are commonly used in biomedical research. Squirrel monkeys (Saimiri spp.) are neotropical primates native to the forests of Central and South America. Of the 7 species of squirrel monkey, 3 (S. oerstedii, S. vanzolinii, and S. ustus) are classified as endangered, vulnerable to extinction in the wild, or near threatened, whereas the remaining 4 (S. boliviensis, S. cassiquiarensis, S. macrodon, and S. sciureus) are not endangered, although the S. cassiquiarensis albigena subspecies is near threatened^52,81 (Figure 1). In South America, where squirrel monkeys are indigenous, breeding colonies of S. sciureus have been maintained at the Pasteur Institute in French Guiana and at the Oswaldo Cruz Foundation in Brazil.^7,12 In the United States, the Squirrel Monkey Breeding and Research Resource, an NIH-sponsored national research resource, maintains breeding colonies for S. boliviensis boliviensis, S. sciureus sciureus, and S. boliviensis peruviensis.Open in a separate windowFigure 1.Taxonomy of Saimiri species with associated IUCN designations.^52,81Squirrel monkeys adapt easily to laboratory housing and can be housed in smaller spaces than can Old World primates.¹ Unlike when working with Old World primates, particularly macaques, no additional personnel protective equipment is necessary when working with squirrel monkeys beyond that recommended for working with other New World primates.⁹² Their small size, combined with the reduced need for personnel protective equipment during handling, make squirrel monkeys attractive species for model development and for studies of viral pathogenesis, which cost approximately 30% to 40% less than comparable studies in macaques.¹ The likelihood of zoonotic transmission of infectious pathogens is considerably less than that associated with macaques and the risk of Macacine herpesvirus 1 (B virus) is nonexistent, given that neotropical primates do not harbor this lethal virus.¹ These factors are increasingly important in the current climate of limited grant funding for biomedical research and emphasis on safety for laboratory personnel. The limited availability of immunologic reagents with specificity for neotropical primates has hindered broader use of squirrel monkeys in biomedical research, compared with that of the more commonly used Old World primates. In addition, the small size of neotropical primates limits the volume of blood that can be collected at any one time. To abrogate these limitations, the NIH Nonhuman Primate Reagent Resource (www.nhpreagents.org) provides an increasing repertoire of agents that have been characterized for immunologic studies of neotropical primates.⁸⁹Squirrel monkeys are used in numerous aspects of biomedical research, including studies of viral persistence, neuroendocrinology, infectious diseases, cancer treatments, vaccine development, gene expression, and reproductive physiology.¹¹⁷ The similarity between the squirrel monkey immune system and that of humans means that, as with macaques, there is a high likelihood that research outcomes will recapitulate what occurs in human diseases.^13,71,87,94 This is particularly true for the study of several notable infectious diseases, including malaria, Creutzfeldt–Jakob disease, and human T-cell leukemia virus type 1 (HTLV1) infection.^19,56,128 For these diseases, squirrel monkeys are the model system of choice for studying pathogenesis, experimental treatments, and strategies for prevention.Squirrel monkeys are recognized as some of the most susceptible nonhuman primate species for the experimental transmission of Creutzfeldt–Jakob disease and other transmissible spongiform encephalopathies that cause chronic wasting disease.^11,72,98,130 The experimental infection of squirrel monkeys with HTLV1 has led to their use in vaccine development and chemotherapy research directed against HTLV1.^44,57,58,82 In addition, squirrel monkeys are an important model for studying the immunology of malaria and for testing vaccines against several Plasmodium species.^19,20,68,114 Furthermore, squirrel monkeys have been used in pharmacologic research to raise HDL levels to prevent atherosclerosis and reduce the risk of coronary heart disease.⁶ As the use of squirrel monkeys increases, especially for infectious disease research, accurate information about the endemic viral infections of squirrel monkeys is needed because of the potential for zoonotic transfer of these viruses to humans (and vice versa) and to understand the potential influence these agents may have on research involving other infectious pathogens diseases and immunosuppressive drugs.     

Calcineurin B-Like Protein-Interacting Protein Kinase CIPK21 Regulates Osmotic and Salt Stress Responses in Arabidopsis

The role of calcium-mediated signaling has been extensively studied in plant responses to abiotic stress signals. Calcineurin B-like proteins (CBLs) and CBL-interacting protein kinases (CIPKs) constitute a complex signaling network acting in diverse plant stress responses. Osmotic stress imposed by soil salinity and drought is a major abiotic stress that impedes plant growth and development and involves calcium-signaling processes. In this study, we report the functional analysis of CIPK21, an Arabidopsis (Arabidopsis thaliana) CBL-interacting protein kinase, ubiquitously expressed in plant tissues and up-regulated under multiple abiotic stress conditions. The growth of a loss-of-function mutant of CIPK21, cipk21, was hypersensitive to high salt and osmotic stress conditions. The calcium sensors CBL2 and CBL3 were found to physically interact with CIPK21 and target this kinase to the tonoplast. Moreover, preferential localization of CIPK21 to the tonoplast was detected under salt stress condition when coexpressed with CBL2 or CBL3. These findings suggest that CIPK21 mediates responses to salt stress condition in Arabidopsis, at least in part, by regulating ion and water homeostasis across the vacuolar membranes.Drought and salinity cause osmotic stress in plants and severely affect crop productivity throughout the world. Plants respond to osmotic stress by changing a number of cellular processes (Xiong et al., 1999; Xiong and Zhu, 2002; Bartels and Sunkar, 2005; Boudsocq and Lauriére, 2005). Some of these changes include activation of stress-responsive genes, regulation of membrane transport at both plasma membrane (PM) and vacuolar membrane (tonoplast) to maintain water and ionic homeostasis, and metabolic changes to produce compatible osmolytes such as Pro (Stewart and Lee, 1974; Krasensky and Jonak, 2012). It has been well established that a specific calcium (Ca²⁺) signature is generated in response to a particular environmental stimulus (Trewavas and Malhó, 1998; Scrase-Field and Knight, 2003; Luan, 2009; Kudla et al., 2010). The Ca²⁺ changes are primarily perceived by several Ca²⁺ sensors such as calmodulin (Reddy, 2001; Luan et al., 2002), Ca²⁺-dependent protein kinases (Harper and Harmon, 2005), calcineurin B-like proteins (CBLs; Luan et al., 2002; Batistič and Kudla, 2004; Pandey, 2008; Luan, 2009; Sanyal et al., 2015), and other Ca²⁺-binding proteins (Reddy, 2001; Shao et al., 2008) to initiate various cellular responses.Plant CBL-type Ca²⁺ sensors interact with and activate CBL-interacting protein kinases (CIPKs) that phosphorylate downstream components to transduce Ca²⁺ signals (Liu et al., 2000; Luan et al., 2002; Batistič and Kudla, 2004; Luan, 2009). In several plant species, multiple members have been identified in the CBL and CIPK family (Luan et al., 2002; Kolukisaoglu et al., 2004; Pandey, 2008; Batistič and Kudla, 2009; Weinl and Kudla, 2009; Pandey et al., 2014). Involvement of specific CBL-CIPK pair to decode a particular type of signal entails the alternative and selective complex formation leading to stimulus-response coupling (D’Angelo et al., 2006; Batistič et al., 2010).Several CBL and CIPK family members have been implicated in plant responses to drought, salinity, and osmotic stress based on genetic analysis of Arabidopsis (Arabidopsis thaliana) mutants (Zhu, 2002; Cheong et al., 2003, 2007; Kim et al., 2003; Pandey et al., 2004, 2008; D’Angelo et al., 2006; Qin et al., 2008; Tripathi et al., 2009; Held et al., 2011; Tang et al., 2012; Drerup et al., 2013; Eckert et al., 2014). A few CIPKs have also been functionally characterized by gain-of-function approach in crop plants such as rice (Oryza sativa), pea (Pisum sativum), and maize (Zea mays) and were found to be involved in osmotic stress responses (Mahajan et al., 2006; Xiang et al., 2007; Yang et al., 2008; Tripathi et al., 2009; Zhao et al., 2009; Cuéllar et al., 2010).In this report, we examined the role of the Arabidopsis CIPK21 gene in osmotic stress response by reverse genetic analysis. The loss-of-function mutant plants became hypersensitive to salt and mannitol stress conditions, suggesting that CIPK21 is involved in the regulation of osmotic stress response in Arabidopsis. These findings are further supported by an enhanced tonoplast targeting of the cytoplasmic CIPK21 through interaction with the vacuolar Ca²⁺ sensors CBL2 and CBL3 under salt stress condition.     

TRAF2 is a biologically important necroptosis suppressor

Tumor necrosis factor α (TNFα) triggers necroptotic cell death through an intracellular signaling complex containing receptor-interacting protein kinase (RIPK) 1 and RIPK3, called the necrosome. RIPK1 phosphorylates RIPK3, which phosphorylates the pseudokinase mixed lineage kinase-domain-like (MLKL)—driving its oligomerization and membrane-disrupting necroptotic activity. Here, we show that TNF receptor-associated factor 2 (TRAF2)—previously implicated in apoptosis suppression—also inhibits necroptotic signaling by TNFα. TRAF2 disruption in mouse fibroblasts augmented TNFα–driven necrosome formation and RIPK3-MLKL association, promoting necroptosis. TRAF2 constitutively associated with MLKL, whereas TNFα reversed this via cylindromatosis-dependent TRAF2 deubiquitination. Ectopic interaction of TRAF2 and MLKL required the C-terminal portion but not the N-terminal, RING, or CIM region of TRAF2. Induced TRAF2 knockout (KO) in adult mice caused rapid lethality, in conjunction with increased hepatic necrosome assembly. By contrast, TRAF2 KO on a RIPK3 KO background caused delayed mortality, in concert with elevated intestinal caspase-8 protein and activity. Combined injection of TNFR1-Fc, Fas-Fc and DR5-Fc decoys prevented death upon TRAF2 KO. However, Fas-Fc and DR5-Fc were ineffective, whereas TNFR1-Fc and interferon α receptor (IFNAR1)-Fc were partially protective against lethality upon combined TRAF2 and RIPK3 KO. These results identify TRAF2 as an important biological suppressor of necroptosis in vitro and in vivo.Apoptotic cell death is mediated by caspases and has distinct morphological features, including membrane blebbing, cell shrinkage and nuclear fragmentation.^{1, 2, 3, 4} In contrast, necroptotic cell death is caspase-independent and is characterized by loss of membrane integrity, cell swelling and implosion.^{1, 2, 5} Nevertheless, necroptosis is a highly regulated process, requiring activation of RIPK1 and RIPK3, which form the core necrosome complex.^{1, 2, 5} Necrosome assembly can be induced via specific death receptors or toll-like receptors, among other modules.^{6, 7, 8, 9} The activated necrosome engages MLKL by RIPK3-mediated phosphorylation.^{6, 10, 11} MLKL then oligomerizes and binds to membrane phospholipids, forming pores that cause necroptotic cell death.^{10, 12, 13, 14, 15} Unchecked necroptosis disrupts embryonic development in mice and contributes to several human diseases.^{7, 8, 16, 17, 18, 19, 20, 21, 22}The apoptotic mediators FADD, caspase-8 and cFLIP suppress necroptosis.^{19, 20, 21, 23, 24} Elimination of any of these genes in mice causes embryonic lethality, subverted by additional deletion of RIPK3 or MLKL.^{19, 20, 21, 25} Necroptosis is also regulated at the level of RIPK1. Whereas TNFα engagement of TNFR1 leads to K63-linked ubiquitination of RIPK1 by cellular inhibitor of apoptosis proteins (cIAPs) to promote nuclear factor (NF)-κB activation,²⁶ necroptosis requires suppression or reversal of this modification to allow RIPK1 autophosphorylation and consequent RIPK3 activation.^{2, 23, 27, 28} CYLD promotes necroptotic signaling by deubiquitinating RIPK1, augmenting its interaction with RIPK3.²⁹ Conversely, caspase-8-mediated CYLD cleavage inhibits necroptosis.²⁴TRAF2 recruits cIAPs to the TNFα-TNFR1 signaling complex, facilitating NF-κB activation.^{30, 31, 32, 33} TRAF2 also supports K48-linked ubiquitination and proteasomal degradation of death-receptor-activated caspase-8, curbing apoptosis.³⁴ TRAF2 KO mice display embryonic lethality; some survive through birth but have severe developmental and immune deficiencies and die prematurely.^{35, 36} Conditional TRAF2 KO leads to rapid intestinal inflammation and mortality.³⁷ Furthermore, hepatic TRAF2 depletion augments apoptosis activation via Fas/CD95.³⁴ TRAF2 attenuates necroptosis induction in vitro by the death ligands Apo2L/TRAIL and Fas/CD95L.³⁸ However, it remains unclear whether TRAF2 regulates TNFα-induced necroptosis—and if so—how. Our present findings reveal that TRAF2 inhibits TNFα necroptotic signaling. Furthermore, our results establish TRAF2 as a biologically important necroptosis suppressor in vitro and in vivo and provide initial insight into the mechanisms underlying this function.     

Parity Modifies Endocrine Hormones in Urine and Problem-Solving Strategies of Captive Owl Monkeys (Aotus spp.)

Parental behavior modifies neural, physiologic, and behavioral characteristics of both maternal and paternal mammals. These parenting-induced modifications extend to brain regions not typically associated with parental responses themselves but that enhance ancillary responses, such as foraging efficiency and predator avoidance. Here we hypothesized that male and female owl monkeys (Aotus spp.) with reproductive experience (RE) would demonstrate more adaptive ancillary behavioral and neuroendocrine responses than those of their nonRE counterparts. To assess cognitive skills and coping flexibility, we introduced a foraging strategy task, including a set of novel objects (coin holders) marked with different symbols representing different food rewards, to the animals. To assess endocrine responses, urine samples were assayed for cortisol and dehydroepiandrosterone (DHEA) levels and their ratios to determine physiologic measures of emotional regulation in RE and nonRE owl monkeys. Compared with nonRE monkeys, experienced parents had higher DHEA:cortisol ratios after exposure to habituation training and on the first day of testing in the foraging task. Both hormones play critical roles in the stress response and coping mechanisms, and a high DHEA:cortisol ratio usually indicates increased coping skills. In addition, RE monkeys exhibited more efficient foraging responses (by 4-fold) than did the nonRE mating pairs. We conclude that RE modifies relevant behavioral and hormonal responses of both maternal and paternal owl monkeys exposed to a challenging cognitive paradigm. Corroborating previous research demonstrating adaptive modifications in foraging efficiency and emotional responses in reproductively experienced rodents, the current results extend these findings to a monogamous primate species.Abbreviations: DHEA, dehydroepiandrosterone; MDS, multidimensional scaling; RE, reproductive experiencePast research has elucidated the fundamental components of pregnancy and motherhood,^39,57,58,78 not only emphasizing the crucial role of the quality of maternal care on infant development^9,27,34 but also revealing how pregnancy and motherhood can reshape the neural, physiologic, and behavioral characteristics of animals.^2,11,36,53 These parent-induced modifications also extend to brain regions that are not directly associated with maternal responses^46,60,63 but instead are involved in enhancing the mother''s efficiency in ancillary parental responses, such as foraging efficiency and predator avoidance. Interestingly, evidence of these maternally related neurobiologic modifications has been confirmed in several species, including humans.^{12,13,39,47,50} For example, compared with animals that lacked reproductive experience (RE), maternal rats exhibited enhanced foraging abilities in a spatial task^37,40 as well as less behavioral and neural evidence of fear reactivity in an open-field task, as expressed by reduced c-fos immunoreactivity in the basolateral amygdala.⁷²Prior research suggests that stress hormones play an integrative role in parent-induced neurobiologic adaptations. Glucocorticoids, for example, have been shown to be suppressed in lactating females, due to blunted activity of the hypothalamic–pituitary–adrenal axis.^6,24,64 Accordingly, the current study assessed the integrative role of both cortisol and dehydroepiandrosterone (DHEA) on adaptive parental responses. Both hormones play critical roles in the stress response and coping mechanisms.¹⁵ DHEA has been shown to be released parallel to cortisol during physical stress²⁸ and has been associated with providing protection against the negative effects of prolonged exposure to glucocorticoids.⁵⁴ Potentially related to the cognitive modifications observed in maternal animals, DHEA can act centrally to decrease glucocorticoid-induced neuronal death in the hippocampus and to promote neurogenesis in the dentate gyrus of the hippocampus and in sensory dorsal root ganglion neurons.⁴⁹ Furthermore, the ratio between DHEA and cortisol has been found to be a reliable index of neuroprotection, because DHEA can increase the proliferation of progenitor cells in the adult hippocampus and also have antidepressant activity.^49,61,70 Accordingly, in the current study, we hypothesized that an increased DHEA:cortisol ratio would be advantageous in parental owl monkeys (Aotus spp.) presented with the metabolically expensive challenges associated with caring for offspring.Although females demonstrate more pronounced parent-induced effects, males experience hormonal alterations associated with copulation, pair-bonding, and paternal care, such as increased vasopressin levels.^{16,41,42,51,55} Research has identified specific neurobiologic modifications that accompany various degrees of paternal responsiveness, including distinct patterns of vasopressin receptor-binding sites and enhanced arginine-, vasopressin-, and oxytocin-immunoreactive cell bodies and fibers, as well as increased neuronal restructuring in the hippocampus.^30,41,79,80 Increased levels of oxytocin and prolactin have been reported in paternal males as well.^{29,67,79,81,82}Owl monkeys (Aotus) are New World monkeys that are characterized by the extensive involvement of fathers in the care of the infant. These primates are small (weight, approximately 1 kg), nocturnal, generalist omnivores that consume fruits, leaves, flowers, insects, and small vertebrate prey.^18,75 Owl monkeys possess prolonged, and probably exclusively, monogamous relationships between the mating pair, enforced through a high level of intrasexual competition.^18,19,53 In biomedical research, owl monkeys have been studied primarily because of their high resistance to parasites, and they are comparative model of herpes virus infection in humans. Consequently, very little is known about the physiologic correlates of their paternal behavior. Due to these characteristics, owl monkeys represent an ideal species in which to investigate the role of RE in the cognitive and emotional responses of animals in captivity.In light of past research emphasizing adaptive effects in reproductively experienced (RE) rodents, we hypothesized that adaptive ancillary behavioral and neuroendocrine responses would be greater in RE male and female owl monkeys than in their nonRE counterparts. To assess the monkeys’ cognitive skills and coping flexibility, we introduced a set of novel objects (coin holders) marked with different symbols representing different food rewards. Arguably, cognitive skills related to foraging are among the most critical adaptations in primates.¹⁷ Furthermore, cortisol and DHEA were evaluated to determine emotional responsivity and resilience in parental owl monkeys. Extending these parental investigations to a nonhuman primate species is necessary to determine the robustness of previously reported findings from laboratory rodents as well as to provide a reliable animal model of the effects of parity on the behavior of captive primates involved in biomedical research.     

A cellular screen identifies ponatinib and pazopanib as inhibitors of necroptosis

Necroptosis is a form of regulated necrotic cell death mediated by receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and RIPK3. Necroptotic cell death contributes to the pathophysiology of several disorders involving tissue damage, including myocardial infarction, stroke and ischemia-reperfusion injury. However, no inhibitors of necroptosis are currently in clinical use. Here we performed a phenotypic screen for small-molecule inhibitors of tumor necrosis factor-alpha (TNF-α)-induced necroptosis in Fas-associated protein with death domain (FADD)-deficient Jurkat cells using a representative panel of Food and Drug Administration (FDA)-approved drugs. We identified two anti-cancer agents, ponatinib and pazopanib, as submicromolar inhibitors of necroptosis. Both compounds inhibited necroptotic cell death induced by various cell death receptor ligands in human cells, while not protecting from apoptosis. Ponatinib and pazopanib abrogated phosphorylation of mixed lineage kinase domain-like protein (MLKL) upon TNF-α-induced necroptosis, indicating that both agents target a component upstream of MLKL. An unbiased chemical proteomic approach determined the cellular target spectrum of ponatinib, revealing key members of the necroptosis signaling pathway. We validated RIPK1, RIPK3 and transforming growth factor-β-activated kinase 1 (TAK1) as novel, direct targets of ponatinib by using competitive binding, cellular thermal shift and recombinant kinase assays. Ponatinib inhibited both RIPK1 and RIPK3, while pazopanib preferentially targeted RIPK1. The identification of the FDA-approved drugs ponatinib and pazopanib as cellular inhibitors of necroptosis highlights them as potentially interesting for the treatment of pathologies caused or aggravated by necroptotic cell death.Programmed cell death has a crucial role in a variety of biological processes ranging from normal tissue development to diverse pathological conditions.^{1, 2} Necroptosis is a form of regulated cell death that has been shown to occur during pathogen infection or sterile injury-induced inflammation in conditions where apoptosis signaling is compromised.^{3, 4, 5, 6} Given that many viruses have developed strategies to circumvent apoptotic cell death, necroptosis constitutes an important, pro-inflammatory back-up mechanism that limits viral spread in vivo.^{7, 8, 9} In contrast, in the context of sterile inflammation, necroptotic cell death contributes to disease pathology, outlining potential benefits of therapeutic intervention.¹⁰ Necroptosis can be initiated by death receptors of the tumor necrosis factor (TNF) superfamily,¹¹ Toll-like receptor 3 (TLR3),¹² TLR4,¹³ DNA-dependent activator of IFN-regulatory factors¹⁴ or interferon receptors.¹⁵ Downstream signaling is subsequently conveyed via RIPK1¹⁶ or TIR-domain-containing adapter-inducing interferon-β,^{8, 17} and converges on RIPK3-mediated^{13, 18, 19, 20} activation of MLKL.²¹ Phosphorylated MLKL triggers membrane rupture,^{22, 23, 24, 25, 26} releasing pro-inflammatory cellular contents to the extracellular space.²⁷ Studies using the RIPK1 inhibitor necrostatin-1 (Nec-1) ²⁸ or RIPK3-deficient mice have established a role for necroptosis in the pathophysiology of pancreatitis,¹⁹ artherosclerosis,²⁹ retinal cell death,³⁰ ischemic organ damage and ischemia-reperfusion injury in both the kidney³¹ and the heart.³² Moreover, allografts from RIPK3-deficient mice are better protected from rejection, suggesting necroptosis inhibition as a therapeutic option to improve transplant outcome.³³ Besides Nec-1, several tool compounds inhibiting different pathway members have been described,^{12, 16, 21, 34, 35} however, no inhibitors of necroptosis are available for clinical use so far.^{2, 10} In this study we screened a library of FDA approved drugs for the precise purpose of identifying already existing and generally safe chemical agents that could be used as necroptosis inhibitors. We identified the two structurally distinct kinase inhibitors pazopanib and ponatinib as potent blockers of necroptosis targeting the key enzymes RIPK1/3.     

Detection and Quantification of Male-Specific Fetal DNA in the Serum of Pregnant Cynomolgus Monkeys (Macaca fascicularis)

Because of their developmental similarities to humans, nonhuman primates are often used as a model to study fetal development for potential clinical applications in humans. The detection of fetal DNA in maternal plasma or serum offers a source of fetal genetic material for prenatal diagnosis. However, no such data have been reported for cynomolgus monkeys (Macaca fascicularis), an important model in biomedical research. We have developed a specific, highly sensitive PCR system for detecting and quantifying male-specific fetal DNA in pregnant cynomolgus monkeys. We used multiplex quantitative real-time PCR to analyze cell-free DNA in maternal blood serum obtained from 46 pregnant monkeys at gestational weeks 5, 12, and 22. The presence of SRY gene and DYS14 Y chromosomal sequences was determined in 28 monkeys with male-bearing pregnancies. According to confirmation of fetal sex at birth, the probe and primers for detecting the Y chromosomal regions at each time point revealed 100% specificity of the PCR test and no false-positive or false-negative results. Increased levels of the SRY-specific sequences (mean, 4706 copies/mL serum DNA; range, 1731 to 12,625) and DYS14-specific sequences (mean, 54,814 copies/mL serum DNA; range, 4175–131,250 copies) were detected at week 22. The SRY- and DYS14-specific probes appear to be an effective combination of markers in a multiplex PCR system. To our knowledge, this report is the first to describe the detection of cell-free DNA in cynomolgus monkeys.Abbreviations: C_t, threshold cycleAnalysis of cell-free circulating nucleic acids in human maternal plasma or serum has led to the development of risk-free methods for prenatal genetic diagnosis and the assessment of several fetal and maternal conditions, for example, sex determination for paternally inherited diseases, pregnancy-associated complications, sex-linked disorders for ambiguous genitalia, and embryo tracking.^{1,4,12,14,18,19} Technical challenges associated with detecting fetal DNA arise due to the low concentration of fetal DNA in maternal plasma during pregnancy and the difficulty of differentiating the genetic material of the fetus from that of the mother.^5,13,20 Fetal sex determination using sequences derived from the Y chromosome only is relatively simple and has a reported accuracy rate in humans of approximately 99.0% at 7 wk of gestation and 100% after 20 wk, depending on the protocol and methods used.^3,5,17,20 In other species, researchers have used real-time PCR assays during pregnancy to predict fetal sex from cell-free DNA at an accuracy of 100%.^9,10,11 Cell-free fetal DNA in the maternal circulation represents only 3% to 6% of the total free DNA obtained from plasma throughout pregnancy; however, this percentage is variable between pregnancies.^5,13,20In clinical biomedical research, it is essential to develop animal models for human diseases to reveal their mechanisms.^16,22 Continued progress in surgical intervention and molecular medicine suggests that it may soon be possible to develop potential treatments or even cures for several fetal genetic diseases at an early stage of pregnancy.¹⁵ Fetal developmental research during early pregnancy might be facilitated by using cell-free fetal DNA in the maternal blood rather than other methods, such as serum screening and ultrasonography. Nonhuman primates, especially macaques, are useful model animals for studying fetal development because of the similarity of the reproductive characteristics, placental structure, and developmental events between these animals and humans.^9,10 These developmental similarities highlight the importance of the study of cell-free fetal DNA in nonhuman primates and its usefulness as a marker to obtain genetic information about the fetus.In the current study, we investigated the presence of cell-free fetal DNA in the maternal plasma of cynomolgus monkeys by developing and using a standardized PCR system. To this end, we selected the SRY (sex-determining region Y) gene and DYS14 sequences of the cynomolgus monkey to use as sex-associated markers. The Y chromosome-specific sequences in the single-copy sex determination region of SRY and the multicopy (thus yielding increased sensitivity) sequences of DYS14 in the TSPY (testis-specific protein, Y-linked) gene have had wide clinical use in humans as molecular markers for detecting and quantifying cell-free fetal DNA.^3,7 In addition, TSPY has been used in bovines for detecting cell-free fetal DNA² and in rhesus macaques for long-term evaluation of microchimerism.⁸ Given the reports of fetal sex determination in rhesus macaques^9,10 and sheep¹¹ by analyzing Y chromosome-specific sequences from cell-free DNA, we hypothesized that we could predict the fetal sex of cynomolgus monkeys at different stages of gestation. This information has been extremely useful in optimizing the design of experimental studies in biomedical research and in managing a nonhuman primate breeding colony.¹⁰ Because cynomolgus and rhesus macaques are closely related members of the same genus, the current experiments are similar to a previous study.⁹We developed an efficient 2-color multiplex PCR system to detect and quantify fetal DNA in the maternal serum of cynomolgus monkeys during pregnancy. We used 2 loci on the Y chromosome in a single PCR test to minimize the likelihood of false-positive signals. Here we report the results of detection and analysis of fetal DNA at various weeks of gestation and evaluate our PCR system for its ability to determine fetal sex from pregnant monkeys’ cell-free DNA.     

Epidemiology of Invasive Klebsiella pneumoniae with Hypermucoviscosity Phenotype in a Research Colony of Nonhuman Primates

Invasive Klebsiella pneumoniae with hypermucoviscosity phenotype (HMV K. pneumoniae) is an emerging human pathogen that, over the past 20 y, has resulted in a distinct clinical syndrome characterized by pyogenic liver abscesses sometimes complicated by bacteremia, meningitis, and endophthalmitis. Infections occur predominantly in Taiwan and other Asian countries, but HMV K. pneumoniae is considered an emerging infectious disease in the United States and other Western countries. In 2005, fatal multisystemic disease was attributed to HMV K. pneumoniae in African green monkeys (AGM) at our institution. After identification of a cluster of subclinically infected macaques in March and April 2008, screening of all colony nonhuman primates by oropharyngeal and rectal culture revealed 19 subclinically infected rhesus and cynomolgus macaques. PCR testing for 2 genes associated with HMV K. pneumoniae, rmpA and magA, suggested genetic variability in the samples. Random amplified polymorphic DNA analysis on a subset of clinical isolates confirmed a high degree of genetic diversity between the samples. Environmental testing did not reveal evidence of aerosol or droplet transmission of the organism in housing areas. Further research is needed to characterize HMV K. pneumoniae, particularly with regard to genetic differences among bacterial strains and their relationship to human disease and to the apparent susceptibility of AGM to this organism.Abbreviations: AGM, African green monkey; HMV K. pneumoniae, invasive Klebsiella pneumoniae with hypermucoviscosity phenotype; NHP, nonhuman primate; RAPD, random amplification of polymorphic DNAKlebsiella pneumoniae is an enteric, gram-negative, lactose-fermenting bacillus with a prominent capsule. This bacterium has been associated with peritonitis, septicemia, pneumonia, and meningitis in both Old and New World primates,^10,13,29 although it also is reported to constitute normal fecal and oral flora in many nonhuman primates (NHP).¹² Pathogenic strains associated with the upper respiratory tract typically are heavily encapsulated.¹² Over the past several decades, human medical literature indicates the emergence of an invasive K. pneumoniae disease in Taiwan and other Asian countries, in which community-acquired pyogenic liver abscesses have been attributed to strains of invasive K. pneumoniae with a unique hypermucoviscous phenotype (HMV K. pneumoniae).^{6,17-19,21,26,34} The hypermucoviscous phenotype has also been associated with other serious complications, including bacteremia, meningitis, and endophthalmitis. This strain of Klebsiella has become an emerging cause of pyogenic liver abscesses in some nonAsian countries, including the United States.^16,20,36,39 The majority of clinical cases of HMV K. pneumoniae are in the Asian population, particularly in patients with diabetes mellitus.^3,4,33 Determination of the HMV phenotype typically is based on a positive string test.^8,35,39Several virulence factors have been associated with HMV K. pneumoniae. Klebsiella spp. generally develop prominent polysaccharide capsules which increase virulence by protecting the bacteria from phagocytosis and preventing destruction by bactericidal serum factors. Capsular serotypes K1 or K2 have been reported as the major virulence determinants for human HMV K. pneumoniae liver abscesses.^5,8,37,38 In addition, the mucoviscosity-associated gene magA, which encodes a structural outer membrane protein of the K1 serotype, and rmpA (regulator of the mucoid phenotype gene; located on a plasmid) have been proposed as virulence factors.^{9,27,31,40,41} Recently, it was suggested that 2 clones, CC23 ^K1 and CC82^K1, are strongly associated with primary liver abscess and respiratory infection, respectively.²Over a period of several months in 2005 to 2006, 7 African green monkeys (AGM; Chlorocebus aethiops) in the US Army Medical Research Institute of Infectious Diseases research colony developed abscesses in multiple locations and either died or were euthanized when the abscesses were determined to be nonresectable.³⁵ HMV K. pneumoniae of the K2 serotype and carrying rmpA was determined to be the cause of the infection in 1 case, and the 6 other cases had similar clinical and pathologic features. This report³⁵ is the only documentation, to our knowledge, of natural infection with HMV K. pneumoniae in NHP. As a result of these cases, the US Army Medical Research Institute of Infectious Diseases instituted policies to exclude HMV K. pneumoniae from the colony. The organism was included as a specific pathogen-free requirement for vendors, and K. pneumoniae culture results were reported during quarantine periods and on routine semiannual examination for all colony NHP.