Pin1 regulates the timing of mammalian primordial germ cell proliferation

Primordial germ cells (PGCs) give rise to male and female germ cells to transmit the genome from generation to generation. Defects in PGC development often result in infertility. In the mouse embryo, PGCs undergo proliferation and expansion during and after their migration to the gonads from 8.5 to 13.5 days post coitum (dpc). We show that a peptidyl-prolyl isomerase, Pin1, is involved in the regulation of mammalian PGC proliferation. We discovered that both the male and female Pin1(-/-) mice had profound fertility defects. Investigation of the reproductive organs revealed significantly fewer germ cells in the adult Pin1(-/-) testes and ovaries than in wild type or heterozygotes, which resulted from Pin1(-/-) males and females being born with severely reduced number of gonocytes and oocytes. Further studies in 8.5 to 13.5 dpc Pin1(-/-) embryos showed that PGCs were allocated properly at the base of the allantois, but their cell expansion was progressively impaired, resulting in a markedly reduced number of PGCs at 13.5 dpc. Analyses using markers of cell cycle parameters and apoptosis revealed that Pin1(-/-) PGCs did not undergo cell cycle arrest or apoptosis. Instead, Pin1(-/-) PGCs had a lower BrdU labeling index compared with wild-type PGCs. We conclude that PGCs have a prolonged cell cycle in the absence of Pin1, which translates into fewer cell divisions and strikingly fewer Pin1(-/-) PGCs by the end of the proliferative phase. These results indicate that Pin1 regulates the timing of PGC proliferation during mouse embryonic development.     

Environmental Management for Malaria Control: Knowledge and Practices in Mvomero,Tanzania

Environmental conditions play an important role in the transmission of malaria; therefore, regulating these conditions can help to reduce disease burden. Environmental management practices for disease control can be implemented at the community level to complement other malaria control methods. This study assesses current knowledge and practices related to mosquito ecology and environmental management for malaria control in a rural, agricultural region of Tanzania. Household surveys were conducted with 408 randomly selected respondents from 10 villages and qualitative data were collected through focus group discussions and in-depth interviews. Results show that respondents are well aware of the links between mosquitoes, the environment, and malaria. Most respondents stated that cleaning the environment around the home, clearing vegetation around the home, or draining stagnant water can reduce mosquito populations, and 63% of respondents reported performing at least one of these techniques to protect themselves from malaria. It is clear that many respondents believe that these environmental management practices are effective malaria control methods, but the actual efficacy of these techniques for controlling populations of vectors or reducing malaria prevalence in the varying ecological habitats in Mvomero is unknown. Further research should be conducted to determine the effects of different environmental management practices on both mosquito populations and malaria transmission in this region, and increased participation in effective techniques should be promoted.     

Discovery of a new class of glucosylceramide synthase inhibitors

A novel series of potent inhibitors of glucosylceramide synthase are described. The optimization of biochemical and cellular potency as well as ADME properties led to compound 23c. Broad tissue distribution was obtained following oral administration to mice. Thus 23c could be another useful tool compound for studying the effects of GCS inhibition in vitro and in vivo.     

The design, synthesis, and biological evaluation of potent receptor tyrosine kinase inhibitors

Variously substituted indolin-2-ones were synthesized and evaluated for activity against KDR, Flt-1, FGFR-1 and PDGFR. Extension at the 5-position of the oxindole ring with ethyl piperidine (compound 7i) proved to be the most beneficial for attaining both biochemical and cellular potencies. Further optimization of 7i to balance biochemical and cellular potencies with favorable ADME/ PK properties led to the identification of 8h, a compound with a clean CYP profile, acceptable pharmacokinetic and toxicity profiles, and robust efficacy in multiple xenograft tumor models.     

Extensive Vascular Mineralization in the Brain of a Chimpanzee (Pan troglodytes)

Spontaneous vascular mineralization (deposition of iron or calcium salts) has been observed in marble brain syndrome, mineralizing microangiopathy, hypothyroidism, Fahr syndrome, Sturge–Weber syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and calciphylaxis in humans and as an aging or idiopathic lesion in the brains of horses, cats, nonhuman primates, mice, rats, cattle, white-tailed deer, and dogs. Here we present a 27-y-old, adult male chimpanzee (Pan troglodytes) with spontaneous, extensive vascular mineralization localized solely to the brain. The chimpanzee exhibited tremors and weakness of the limbs, which progressed to paralysis before euthanasia. Magnetic resonance brain imaging in 2002 and 2010 (immediately before euthanasia) revealed multiple hypointense foci, suggestive of iron- and calcium-rich deposits. At necropsy, the brain parenchyma had occasional petechial hemorrhage, and microscopically, the cerebral, cerebellar and brain stem, gray and white matter had moderate to severe mural aggregates of a granular, basophilic material (mineral) in the blood vessels. In addition, these regions often had moderate to severe medial to transmural deposition of mature collagen in the blood vessels. We ruled out common causes of brain mineralization in humans and animals, but an etiology for the mineralization could not be determined. To our knowledge, mineralization in brain has been reported only once to occur in a chimpanzee, but its chronicity in our case makes it particularly interesting.Spontaneous vascular mineralization (deposition of iron or calcium salts) has been reported to occur in the brains of both humans and animals. This symptom has been observed in marble brain syndrome, mineralizing microangiopathy, hypothyroidism, Fahr syndrome, Sturge–Weber syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and calciphylaxis in humans^1,2,3,4 and as an aging or idiopathic lesion in the brains of horses, cats, nonhuman primates, mice, rats, cattle, white-tailed deer and dogs.^{5,6,7, 8-11} Vessels of the internal capsule, globus pallidus, cerebellar dentate nucleus, and infrequently, hippocampus are affected preferentially in horses, cattle, and, less commonly, dogs.⁷ Meningeal vessels in old cats, old horses, and cattle as well as vessels in the choroid plexus of old cats are other sites of vascular mineralization, but obvious ischemic damage is rarely associated with mineralization as a primary lesion in any animal species.⁷ Here we present a chimpanzee (Pan troglodytes) with extensive vascular mineralization that was localized solely to the brain.     

Pacific Walrus (Odobenus rosmarus divergens) Resource Selection in the Northern Bering Sea

The Pacific walrus is a large benthivore with an annual range extending across the continental shelves of the Bering and Chukchi Seas. We used a discrete choice model to estimate site selection by adult radio-tagged walruses relative to the availability of the caloric biomass of benthic infauna and sea ice concentration in a prominent walrus wintering area in the northern Bering Sea (St. Lawrence Island polynya) in 2006, 2008, and 2009. At least 60% of the total caloric biomass of dominant macroinfauna in the study area was composed of members of the bivalve families Nuculidae, Tellinidae, and Nuculanidae. Model estimates indicated walrus site selection was related most strongly to tellinid bivalve caloric biomass distribution and that walruses selected lower ice concentrations from the mostly high ice concentrations that were available to them (quartiles: 76%, 93%, and 99%). Areas with high average predicted walrus site selection generally coincided with areas of high organic carbon input identified in other studies. Projected decreases in sea ice in the St. Lawrence Island polynya and the potential for a concomitant decline of bivalves in the region could result in a northward shift in the wintering grounds of walruses in the northern Bering Sea.     

Cerebrovascular Accident (Stroke) in Captive,Group-Housed,Female Chimpanzees

Over a 5-y period, 3 chimpanzees at our institution experienced cerebrovascular accidents (strokes). In light of the increasing population of aged captive chimpanzees and lack of literature documenting the prevalence and effectiveness of various treatments for stroke in chimpanzees, we performed a retrospective review of the medical records and necropsy reports from our institution. A survey was sent to other facilities housing chimpanzees that participate in the Chimpanzee Species Survival Plan to inquire about their experience with diagnosing and treating stroke. This case report describes the presentation, clinical signs, and diagnosis of stroke in 3 recent cases and in historical cases at our institution. Predisposing factors, diagnosis, and treatment options of cerebral vascular accident in the captive chimpanzee population are discussed also.Abbreviations: CVA, cerebrovascular accidentCerebrovascular accident (CVA; stroke) is a disturbance in brain function due to insufficient or complete loss of blood supply to an area of the brain. The lesion and clinical signs depend on the severity and location of the blockage. The 2 main categories of stroke—ischemic and hemorrhagic—both result in a loss of blood flow to an associated area of the brain. Ischemic strokes are due to either insufficient or direct loss of blood flow to the affected area of the brain from either temporary or permanent arterial occlusion of vessels supplying that area. Hemorrhagic strokes occur from rupture of a blood vessel and subsequent leakage of blood intracranially or into the subarachnoid space which results in clotting and decreased blood flow within that vessel and compression of the brain.^8,14,16,19 Loss of blood supply to a part of the brain, which can occur with ischemic or hemorrhagic stroke, initiates an ischemic cascade. The ischemic cascade is the result of secondary lack of oxygen and glucose; this lack consequently changes the intracellular metabolism from aerobic to anaerobic. This process ultimately leads to cell death and resultant disruption of cell membranes, thereby releasing toxins into the surrounding area and leading to increased cell death. This process results in a centrifugal progression of irreversible tissue damage and cell death.^1,11Brain tissue ceases to function when deprived of oxygen for more than 60 to 90 s, and irreversible tissue necrosis and brain damage can occur after a few hours. Ischemic strokes can result in varying degrees of damage to the tissue; consequently, clinical signs depend upon the amount of collateral circulation supplying the affected region of the brain. Part of the tissue may die immediately, whereas other parts may be injured only temporarily and ultimately recover.⁸ Clinical signs that are typical of stroke victims consist of abnormal sensations, hemiparesis (that is, paralysis in one arm or leg or on one side of the body), aphasia, ataxia, and urinary incontinence. Severe strokes can result in stupor or coma. The defect in the brain usually is manifested as clinical signs on the opposite side of the body, depending on the part of brain that is affected.^8,9 Diagnosis typically is based initially on clinical signs and confirmed with imaging techniques such as CT and MRI, or the lesion is noted at necropsy.^6,16Whereas strokes are common in humans, only one report to date has discussed and documented spontaneous stroke in a chimpanzee.⁶ In 2004, a 29-y-old male chimpanzee at a zoo experienced an ischemic stroke that most likely was due to occlusion of the middle cerebral artery.^2,6 The area of the brain supplied by the middle cerebral artery is the area most often affected in ischemic stroke in humans.^2,10 Although stroke has not been thoroughly researched in chimpanzees, studies in other species of nonhuman primates suggest that the predisposing factors and pathology are similar to those in humans.^3,18,20This case report describes the presentation, clinical signs, and diagnosis of CVA that occurred in 3 chimpanzees over a 5-y period at our institution and in an additional 3 animals identified during a retrospective review of the health records from the last 30 y. We also discuss predisposing factors, diagnosis, treatment options, and statistics of CVA in the captive chimpanzee population.     

Osteochondromatosis in a Rhesus macaque (Macaca mulatta)

A 5-y-old, male, rhesus macaque (Macaca mulatta) presented with a prominent mass slightly anteriomedial to the right stifle. On exam, multiple radiopaque masses were identified protruding from the mid- and distal femur. Lateral and anteroposterior radiographs of the right stifle region revealed multiple exophytic masses arising from the femur, with mild bony reaction of the proximal tibia. Histologic examination of biopsy tissue revealed woven and lamellar bone with granulation tissue and skeletal muscle. Because the macaque was exhibiting no lameness or signs of pain, we decided to monitor the progression of the masses. Minimal change was noted during the time prior to study termination at 6.5 y of age. Necropsy revealed that the bony masses were cartilage-capped lesions arising near the growth plate of the distal femur and midshaft of the femur and tibia. Histologic examination revealed chondro-osseous exophytic growths that blended imperceptibly with the cortex and spongiosa of the femur, consistent with a final diagnosis of multiple osteochondromas.     

Spermatogonial depletion in adult Pin1-deficient mice

Spermatogonia in the mouse testis arise from early postnatal gonocytes that are derived from primordial germ cells (PGCs) during embryonic development. The proliferation, self-renewal, and differentiation of spermatogonial stem cells provide the basis for the continuing integrity of spermatogenesis. We previously reported that Pin1-deficient embryos had a profoundly reduced number of PGCs and that Pin1 was critical to ensure appropriate proliferation of PGCs. The current investigation aimed to elucidate the function of Pin1 in postnatal germ cell development by analyzing spermatogenesis in adult Pin1-/- mice. Although Pin1 was ubiquitously expressed in the adult testis, we found it to be most highly expressed in spermatogonia and Sertoli cells. Correspondingly, we show here that Pin1 plays an essential role in maintaining spermatogonia in the adult testis. Germ cells in postnatal Pin1-/- testis were able to initiate and complete spermatogenesis, culminated by production of mature spermatozoa. However, there was a progressive and age-dependent degeneration of the spermatogenic cells in Pin1-/- testis that led to complete germ cell loss by 14 mo of age. This depletion of germ cells was not due to increased cell apoptosis. Rather, detailed analysis of the seminiferous tubules using a germ cell-specific marker revealed that depletion of spermatogonia was the first step in the degenerative process and led to disruption of spermatogenesis, which resulted in eventual tubule degeneration. These results reveal that the presence of Pin1 is required to regulate proliferation and/or cell fate of undifferentiated spermatogonia in the adult mouse testis.