Babesia microti: Biochemistry and function of hamster erythrocytes infected from a human source

Babesia microti, a protozoan parasite of mammalian erythrocytes was obtained from the blood of an infected human and maintained in golden hamsters, in which a parasitemia of 70% was obtained regularly. The hamsters' response—a subacute, hemolytic anemia—was studied with regard to oxygen affinity and red cell organic phosphate content. In addition, the reduced glutathione status of infected erythrocytes was observed because of the possible importance of this metabolite to parasite growth and red cell integrity. Infected animals developed a severe anemia with reticulocytosis; there occurred a 4-mm decrease in whole blood oxygen affinity without any change in erythrocytes' 2,3-diphosphoglycerate levels. The glutathione content of the infected animals' erythrocytes increased twofold during the course of the infection. In uninfected animals, in which anemia and reticulocytosis had been produced by bleeding, all changes seen in infected animals were reproduced. It was concluded that the changes in the infected animals were due to the anemia and reticulocytosis alone, and that the parasite played no role in these changes apart from being a cause of anemia and reticulocytosis.     

Effects of circulating red cell mass on diet-induced atrial thrombosis in mice

Atrial thrombosis is a common lesion in female Taconic Swiss mice fed a high-fat (28%), low-protein (8%), hypolipotropic diet for 10 wk or longer. After the third week of such feeding the mice studied here were injected with either erythropoietin, washed, packed red blood cells, lysed red blood cells, plasma or physiological saline.In mice receiving injections of lysed red cells, plasma or saline, respectively 75, 54 and 82% of those surviving for 10 wk had developed atrial thrombosis. Hematocrits were 9.3% or below in these groups. Hematocrits were maintained at an average of 33.0% in the erythropoietin group and 32.4% in the transfused (packed erythrocytes) group. Only one of the erythropoietin injected animals and none of the transfused animals developed atrial thrombosis. The evidence indicates that the anemia induced by the experimental diet results from lack of erythropoietin production or activity and that the hypoxia of anemia plays a role in the development of atrial thrombosis.     

Karyotypic variation in susceptibility to hemolytic anemia and idiopathic eosinophilia of owl monkeys,Aotus trivirgatus

Hematologic data gathered over a period of 4.8 years from 196 owl monkeys,Aotus trivirgatus, were analyzed to find if karyotypic differences existed. It was found that none of 30 animals of karyotypes K-I and K-VI developed hemolytic anemia, whereas 46 of 99 animals of K-II, K-III and K-IV did (p<0.005). Analysis of hemograms of normal owl monkeys showed that mean percent eosinophils varied markedly, K-I monkeys having lowest counts, 3.2%, and K-VI animals having the highest, 33%. These results establish that idiopathic eosinophilia and hemolytic anemia in this species are probably unrelated but susceptibility to both has a strong genetic component.     

Trypanosoma brucei: attenuation by cortcosteroids of the anemia of infected mice

BALBc/J mice infected with pleomorphic stabilate of Trypanosoma brucei develop a severe anemia. The anemia is initially normoblastic and normocytic but becomes macrocytic due to brisk and sustained reticulocytosis. Red blood cells from uninfected animals are destroyed when transfused into infected animals. Neither extensive intravascular hemolysis nor red cell agglutinins were detected in infected animals, but spherocytes were common in the peripheral circulation. Treatment of mice with either dexamethasone or hydrocortisone greatly retarded the development of the anemia. Comparison of the course of infection in these treated mice to that in normal mice suggests that these corticosteroids attenuate the anemia through their immunosuppressive action.     

Severe anemia affects both splenectomized and non-splenectomized Plasmodium falciparum-infected Aotus infulatus monkeys

Severe anemia is the earliest and a frequently fatal complication of Plasmodium falciparum infection. Here we describe Aotus infulatus as a primate model suitable to study this malaria complication. Both non-splenectomized and splenectomized monkeys receiving different inocula of P. falciparum FVO strain presented large (> 50%) decreases in hematocrit values during infection. Non-splenectomized animals were able to control parasite growth (parasitemia did not exceed 4%), but they had to be treated because of severe anemia. Three of 4 splenectomized monkeys did not control parasitemia and were treated, but developed severe anemia after treatment when presenting a negative blood film. Destruction of parasitized red blood cells alone cannot account for the degree of anemia. Non-splenectomized monkeys repeatedly infected with homologous parasites became rapidly and progressively resistant to reinfection and to the development of severe anemia. The data presented here point to A. infulatus as a suitable model for studying the pathogenesis of severe malarial infection.     

Corynebacterium Pseudotuberculosis Infection in Goats VI.

Twelve kids, 5 1/2 months old, were inoculated intravenously with about 1 million colony forming units of a Corynebacterium pseudotuberculosis strain isolated from goat. Nine of the animals had antibodies against the organism in the bacterial agglutination test and/or the hemolysis inhibition test before they were inoculated. Four kids developed acute toxemia and died 2–5 days after the inoculation. Three of these animals were negative in both the bacterial agglutination test and the hemolysis inhibition test, while the fourth was positive in the bacterial agglutination test only. Post mortem examination revealed severe icterus, anemia, hemoglobinuria and acute pneumonia with microabscess formation in 3 of the kids that died. Eight animals, all with antibodies against C. pseudotuberculosis, developed acute illness but survived the inoculation. These animals were sacrificed and examined post mortem 1 month after the experimental infection, and abscesses were demonstrated in internal organs in all cases. It is concluded that intravenous inoculation with C. pseudotuberculosis is not a suitable challenge system to study the prophylactic efficacy of vaccines against caseous lymphadenitis in goats.     

Multifactorial etiology of anemia in SIV-infected rhesus macaques: Decreased BFU-E formation,serologic evidence of autoimmune hemolysis,and an exuberant erythropoietin response

We attempted to define the etiology of anemia in SIV-infected rhesus macaques. Bone marrow culture showed significantly decreased (75% reduction) burst forming unit-erythroid (BFU-E) growth in end-stage SIV⁺ “sick” animals. Direct antiglobulin tests (DAT) were positive in nine of 35 SIV⁺ “well” and 14 of 14 SIV⁺ “sick” monkeys (0 of 25 control animals had positive DATs). In animals with a positive DAT, moderate to severe anemia was observed, as was increased LDH and spherocytosis. Erythropoietin was measured in four control, eight SIV⁺ “well” and five SIV⁺ “sick” animals with mean levels of 4.0, 15.4, and 1176 mU/mL (r = .94) in the three groups. These data suggest that the cause of anemia in the SIV-infected rhesus macaque is multifactorial, that there may be a defect in erythropoiesis, and that, serologically, an IgG mediated autoimmune hemolytic anemia is also present.     

Aotus infulatus monkey is susceptible to Plasmodium falciparum infection and may constitute an alternative experimental model for malaria

Aotus is one of the WHO-recommended primate models for studies in malaria, and several species can be infected with Plasmodium falciparum or P. vivax. Here we describe the successful infection of the species A. infulatus from eastern Amazon with blood stages of P. falciparum. Both intact and splenectomized animals were susceptible to infection; the intact ones were able to keep parasitemias at lower levels for several days, but developed complications such as severe anemia; splenectomized monkeys developed higher parasitemias but no major complications. We conclude that A. infulatus is susceptible to P. falciparum infection and may represent an alternative model for studies in malaria.     

Surgical bone marrow aspiration in Aotus lemurinus griseimembra

Aotus lemurinus griseimembra are highly susceptible to infection by human malaria parasites and reproduce some of its clinical manifestations, including anemia. We developed a new surgical technique to obtain bone marrow samples from Aotus by surgical aspiration of the femur. First, we determined that the femur offered advantages over other bones, primarily due to lower fracture vulnerability. We tested a surgical technique using 20 G IV catheters in formaldehyde-preserved animals, then conducted the procedure on 27 live animals. This technique provided easy, quick surgical access to adequate volumes of bone marrow and was safe for almost all animals: only one died; another developed nervous impairment of the lower limb. Adequate cell samples were obtained in all animals and allowed cytological studies. This procedure offers a useful tool for bone marrow research in Aotus and helps overcome current limitations of such research in human where these studies are limited by ethical and technical issues.     

Erythropoietin titers in response to anemia or hypoxia

The normal response to anemic or hypoxic hypoxia is synthesis and release of erythropoietin in accord with the concept that erythropoietin production is controlled by a renal oxygen sensor. In this study, erythropoietin production, as predicted, was abrogated in patients with renal impairment (55 cases), but normal in nonuremic individuals. Specifically, patients with rheumatoid arthritis (34 cases), sickle cell anemia (25 cases), aregenerative anemia (27 cases), and aplastic anemia (13 cases) had erythropoietin titers overlapping with those observed in simple anemia (61 cases) at corresponding hematocrits. The response of polycythemic laboratory animals to hypoxia is more difficult to fit within the concept of an oxygen sensor responsive both to anemic and hypoxic hypoxia. If the polycythemia was induced by hypertransfusion, erythropoietin production in response to hypoxia was, as predicted, less than that observed in normal animals. If, however the polycythemia was induced by previous exposure to hypoxia, the animals responded to hypoxia as though they were not polycythemic. An explanation for this challenging observation may provide a clue as to the operation of the oxygen sensor.     

Blood viscosity and cardiac output in acute experimental anemia.

The significance of blood viscosity alterations during anemia was evaluated in dogs under morphine-chloralose anesthesia. In group I, anemia (mean hematocrit 18.1 +/- 1.3 vol %) was produced by exchange transfusion with clinical dextran (avg mol wt 70,000). In group II, anemia was produced (mean hematocrit 19.9 +/- 0.88 vol %) with 500,000 molecular weight dextran, thus preventing the decrease in blood viscosity in group I. The cardiac output increase in group I (93.4%) with low-viscosity anemia was significantly greater than in group II (43.3%) with unchanged blood viscosity. Group III animals were transfused with a clinical dextran-red cell mixture, and group IV animals received a 500,000 mol wt dextran-red cell mixture. In group III, blood viscosity and cardiac output did not change. In group IV, blood viscosity rose and cardiac output fell significantly. The results suggest that a change in blood viscosity exerts a significant effect upon cardiac output, especially during acute dextran-exchange anemia.     

Experimental acute Babesia caballi infections: I. Red blood cell dynamics

Hematological determinations were made on blood samples from six ponies acutely infected with two dosage levels of Babesia caballi (Group 1: divided into two subgroups of three ponies each). Similar determinations were made on blood samples from three premunized ponies given challenge inoculations (Group 2), and three equidae given uninfected red blood cells (Group 3).A trend towards decreases in RBC counts, hemoglobin concentrations, and hematocrits within one to four days after inoculation (AI) was observed in all groups. However, it was marked only in Group 1. In addition, only in Group 1 was there observed a concerted anemia occurring between Days 7 and 16.Those surviving ponies in Group 1 which developed a higher parasitemia between Days 5 and 6 AI (first parasitemia peak) developed a more severe anemia between Days 7 and 16. Ponies which developed parasitemias higher than 40 × 10³ parasitized cells/mm³ at the first parasitemia peak subsequently died.Free bilirubin in Group 1 animals increased immediately after inoculation, and repeatedly exceeded normal ranges until after Day 20 AI when the RBC counts were rising. Similar changes in free bilirubin did not occur in either Groups 2 or 3. Conjugated bilirubin levels did not exceed normal ranges in any of the experimental animals.Active erythrophagocytosis was evident in histological preparations of lymph node, spleen, liver, and lung from ponies which died. Cytosiderin pigment was present in liver parenchyma, and hematin was scattered throughout lymph nodes and spleen.     

Selection of peptides for serological detection of equine infectious anemia

Equine infectious anemia caused by equine infectious anemia virus is an important disease due to its high severity and incidence in animals. We used a phage display library to isolate peptides that can be considered potential markers for equine infectious anemia diagnosis. We selected peptides using IgG purified from a pool comprised of 20 sera from animals naturally infected with equine infectious anemia virus. The diagnostic potential of these peptides was investigated by ELISA, Western blot and dot blot with purified IgG and serum samples. Based on the results, we chose a peptide mimetic for glycoprotein gp45 epitopes of equine infectious anemia virus, with potential for use as an antigen in indirect diagnostic assays. Synthesis of this peptide has possible applications for the development of new diagnostic tools for this disease.     

口服苯肼致小鼠慢性贫血模型的建立

目的:应用苯肼建立小鼠急性溶血性贫血的方法已经成熟,但用苯肼建立慢性溶血性贫血模型尚未见报道。本研究试图应用苯肼口服法建立慢性溶血性贫血动物模型并探索最适建模的苯肼浓度。方法:42只C57BL/6小鼠随机分为6组通过口服不同浓度的苯肼溶液,于口服后的第0,1,2,3,4,5,6周目内眦采集小鼠外周血检测,记录相关指标变化比较各组之间的差异,筛选出最佳慢性溶血效果的给药浓度。结果:口服苯肼溶液浓度在250 mg/L以下时C57BL/6小鼠没有出现明显的贫血状态,当浓度调至250mg/L-350mg/L时可使C57BL/6小鼠在5-7周内出现溶血性贫血症状,各组小鼠的皮肤和粘膜颜色苍白,外周血红细胞数量、血红蛋白含量、红细胞压积降低网织红细胞比例增高。但是当浓度达到350 mg/L时小鼠贫血情况过重且达不到慢性贫血的要求。当浓度为300 mg/L时小鼠各项血液指标平稳下降。结论:本实验建立了一种新的小鼠慢性贫血模型,且通过实验发现小鼠口服苯肼致慢性贫血的最佳浓度为300mg/L。据我们所知,这是首次使用苯肼建立慢性贫血的动物模型,此模型对研究人类慢性贫血具有重要价值。     

Trypanosoma congolense: lack of correlation between the resistance of cattle subjected to experimental cyclic infection or to field challenge

Twelve male cattle of the Baoulé breed were exposed to natural trypanosome challenge in an area of high Glossina density, to characterize them as trypanoresistant or trypanosensitive. Weekly blood samples were taken for the determination of parasitemia and packed cell volume, as a measure of anemia. Seven Zebu cattle were also exposed to challenge at the same time. The Zebu proved to be trypanosensitive with high parasitemia, pronounced anemia and died or were drug treated in extremis. Five Baoulé were as sensitive as the Zebu while 7 others were trypanoresistant since they showed little or no patent parasitemia, only mild transient anemia and survived in good condition. The 12 Baoulé were allowed to recover from challenge in the field and along with 7 Zebu were subjected to experimental fly challenge in fly-proof accommodation. Glossina morsitans submorsitans infected with a clone of Trypanosoma congolense derived from the stock Serengeti/71/STIB/212 were allowed to engorge on the shaven flanks of tranquilized animals. All animals showed persistent parasitemia for at least 7 weeks, including all the Baoulé resistant to natural challenge. Two Baoulé, one resistant and one sensitive to natural challenge, and 4/7 Zebu appeared unable to control parasitemia, had severe anemia, and were drug treated in extremis. The remaining Baoulé, 6 resistant and 4 sensitive, appeared to be undergoing spontaneous cure by Week 9-10, as did 3/7 Zebu. In Zebu, anemia was as pronounced as under natural challenge. Three resistant Baoulé maintained packed cell volume above 30 as under field challenge but the others showed marked anemia. On the contrary, 4 sensitive Baoulé showed only slight anemia after artificial fly challenge.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental gastric carcinogenesis in Cebus apella nonhuman primates

The evolution of gastric carcinogenesis remains largely unknown. We established two gastric carcinogenesis models in New-World nonhuman primates. In the first model, ACP03 gastric cancer cell line was inoculated in 18 animals. In the second model, we treated 6 animals with N-methyl-nitrosourea (MNU). Animals with gastric cancer were also treated with Canova immunomodulator. Clinical, hematologic, and biochemical, including C-reactive protein, folic acid, and homocysteine, analyses were performed in this study. MYC expression and copy number was also evaluated. We observed that all animals inoculated with ACP03 developed gastric cancer on the 9(th) day though on the 14(th) day presented total tumor remission. In the second model, all animals developed pre-neoplastic lesions and five died of drug intoxication before the development of cancer. The last surviving MNU-treated animal developed intestinal-type gastric adenocarcinoma observed by endoscopy on the 940(th) day. The level of C-reactive protein level and homocysteine concentration increased while the level of folic acid decreased with the presence of tumors in ACP03-inoculated animals and MNU treatment. ACP03 inoculation also led to anemia and leukocytosis. The hematologic and biochemical results corroborate those observed in patients with gastric cancer, supporting that our in vivo models are potentially useful to study this neoplasia. In cell line inoculated animals, we detected MYC immunoreactivity, mRNA overexpression, and amplification, as previously observed in vitro. In MNU-treated animals, mRNA expression and MYC copy number increased during the sequential steps of intestinal-type gastric carcinogenesis and immunoreactivity was only observed in intestinal metaplasia and gastric cancer. Thus, MYC deregulation supports the gastric carcinogenesis process. Canova immunomodulator restored several hematologic measurements and therefore, can be applied during/after chemotherapy to increase the tolerability and duration of anticancer treatments.     

Identification of a haemomycoplasma species in anemic reindeer (Rangifer tarandus)

During an 18-mo period (May 2002-November 2003), 10 animals in a herd of 19 reindeer (Rangifer tarandus) at the National Animal Disease Center (NADC) experienced episodes of anemia. Affected animals had histories of weight loss, unthriftiness, occasionally edema of dependent parts and moderate anemia characterized by microcytosis or macrocytosis, hypochromasia, schistocytosis, keratocytosis, acanthocytosis, and dacryocytosis. Numerous basophilic punctate to ring-shaped bodies, measuring less than 1.0 microm, were found on the surface of red blood cells and were often observed encircling the outer margins of the cells. Based on cytologic findings, DNA preparations from selected affected animals in the NADC herd and one animal from a private herd experiencing similar episodes of anemia were assayed by polymerase chain reaction (PCR) for the presence of hemotropic bacteria using primers targeting the 16S rRNA genes of Mycoplasma (Eperythrozoon) suis, Mycoplasma (Haemobartonella) haemofelis, Anaplasma marginale, Anaplasma spp., and Ehrlichia spp. Amplification products were detected from four of the affected animals using primers specific for the 16S rRNA gene of M. haemofelis and Mycoplasma haemocanis. Product from one of the animals was sequenced and internal primers were designed from the resulting sequence to perform a nested PCR assay. Samples from 10 reindeer were positive using the nested PCR reaction and products from seven animals were sequenced; BLAST searches and phylogenetic analysis were performed on the resulting sequences. Sequence data from six animals revealed homology to an organism most closely related to Mycoplasma ovis, Mycoplasma wenyonii, and Mycoplasma haemolamae; sequence from a single animal was most closely related to M. haemofelis and M. haemocanis. This represents the first identification of a haemomycoplasma species in reindeer. Although several animals were also infected with abomasal nematodes, the presence of this newly described haemomycoplasma may have contributed to the anemic syndrome.     

Interactive effects of anemia and muscle oxidative capacity on exercise endurance

We used endurance training and acute anemia to assess the interactions among maximal oxygen consumption (VO2max), muscle oxidative capacity, and exercise endurance in rats. Animals were evaluated under four conditions: untrained and endurance-trained with each group subdivided into anemic (animals with reduced hemoglobin concentrations) and control (animals with unchanged hemoglobin concentrations). Anemia was induced by isovolemic plasma exchange transfusion. Hemoglobin concentration and hematocrit were decreased by 38 and 41%, respectively. Whole body VO2max was decreased by 18% by anemia regardless of training condition. Anemia significantly reduced endurance by 78% in untrained rats but only 39% in trained animals. Endurance training resulted in a 10% increase in VO2max, a 75% increase in the distance run to exhaustion, and 35, 45, and 58% increases in skeletal muscle pyruvate-malate, alpha-ketoglutarate, and palmitylcarnitine oxidase activities, respectively. We conclude that endurance is related to the interactive effects of whole body VO2max and muscle oxidative capacities for the following reasons: 1) anemic untrained and trained animals had similar VO2max but trained rats had higher muscle oxidative capacities and greater endurance; 2) regardless of training status, the effect of acute anemia was to decrease VO2max and endurance; and 3) trained anemic rats had lower VO2max but had greater muscle oxidative capacity and greater endurance than untrained controls.     

Experimental Babesia gibsoni infection in coyotes (Canis latrans)

Four 5 mo old captive raised coyotes (Canis latrans) were experimentally inoculated with approximately 1 x 10(6) Babesia gibsoni organisms. Parasites were detected 1 wk post-inoculation in all coyotes with maximum parasitemia of 8-11% occurring at 34 wk. Parasitemias remained at or above 1% for at least 12 wk and were still detectable 20 wk post-inoculation. All experimentally infected coyotes developed pale mucous membranes, splenomegaly, and a positive heme reaction in urine while one coyote exhibited mild depression and inappetence. Infected coyotes also developed a regenerative anemia, thrombocytopenia, and neutropenia. The mild clinical signs coupled with the high level and long duration of parasitemia indicate that coyotes could serve as reservoirs for B. gibsoni. Entrance of this foreign parasite into the United States suggests the need for strict quarantines and thorough health and blood film examinations for imported animals.     

Haemobartonella canis infection in research dogs.

During 1970-1972 haemobartonellosis occurred in research canines at 2 widely separated institutions. Clinical anemia occurred in a splenectomized dog at a Maryland facility, and subsequent screening disclosed an infection rate of 65% in a group of 20 splenectomized subjects. Treatment was successful, and the animals were used in research. A research institution in Texas encountered a number of dogs with fever (to 106 degrees F) and eosinophilia (to 42%) following minor surgery. Blood from affected animals was injected iv into splenectomized dogs, and 3 of 6 recipients developed haemobartonellosis. Further study was conducted, with some success, to establish a relationship between fever and eosinophilia and Haemobartonella canis infection in nonsplenectomized subjects. Our experiences suggest that haemobartonellosis is a widespread, latent disease of dogs and that significant potential exists for the infection to adversely affect research results.