Comparisons of hemodynamics throughout the life span of the Bio 14.6 cardiomyopathic with the F1B normal hamster

1. Comparisons of left intraventricular end diastolic and systolic pressures, cardiac output, dP/dt, stroke volume and heart rate were made between the Bio 14.6 cardiomyopathic and F1B normal hamster at 45, 80, 150 and 240 days of age. 2. Comparisons of the ventricular calcium and taurine contents were made between the two strains of hamsters at similar ages. 3. Interstrain comparisons of the 240 day Bio 14.6 with age matched F1B hamsters and intrastrain comparisons with 45 day Bio 14.6 hamsters showed a decreased stroke volume, cardiac output and dP/dt with an increased left intraventricular end diastolic pressure, ventricular weight, ventricular weight/body weight ratio, heart calcium and taurine. 4. Despite the decreased left ventricular systolic pressure and cardiac output in the 80 day and older groups of Bio 14.6 hamsters, no compensatory increase in heart rate was observed.     

Alloimmune reactions among recently wild syrian hamsters and classical inbred strains include alloantibody production

Partially inbred lines of Syrian hamsters, the descendants of animals caught wild in Syria within the past decade, have been studied to determine their immunogenetic relationships to the long established domestic inbred strains. These new sources of hamster genes display strong alloimmune reactions when confronted with tissues from the domestic inbred strains and vice versa: acute skin graft rejection, strong mixed lymphocyte reactions, and intense graft-versus-host reactions. While these forms of reactivity have also characterized the disparities among the domestic inbred strains, no evidence of alloantibodies specific for putative transplantation antigens has ever been found in hamsters. We report, for the first time, that immunization of recently wild hamsters with tissues from domestic inbred strain donors elicits high titer cytotoxic antibodies directed at alloantigens. Similarly, animals of the domestic inbred strains produce comparably strong alloantibody responses when immunized with tissues from the recently wild hamsters. Availability of these alloantisera will make the possibility of defining the major histocompatibility complex equivalent in this species much more likely.     

Pichinde virus-specific cell-associated suppression of primary footpad swelling in an inbred strain of Syrian hamsters

Pichinde virus causes a lethal disease after i.p. inoculation of adult MHA hamsters; other strains of Syrian hamsters are resistant to this lethal infection. During studies of cell-mediated immune responses to Pichinde virus, it was noted that MHA hamsters survived infection when the virus was given in the footpad. However, unlike the resistant LSH and LVG strains of hamsters, the MHA hamsters did not manifest a footpad swelling response. Failure of the MHA hamster to respond to a footpad inoculation of Pichinde virus was shown to be virus-specific and appeared to be mediated by a cell-associated suppressor mechanism.     

Serum chemistry reference values in two strains of Syrian hamsters

Blood samples were collected from 30 male and female hamsters (Mesocricetus auratus) from two sources. Serum was collected and analyzed for 17 biochemical values. The results were analyzed statistically and comparisons were made between males and females and between strains.     

Susceptibility of inbred Syrian golden hamsters (Mesocricetus auratus) to lethal disease by lymphocytic choriomeningitis virus

An acutely lethal LCMV disease model has been established in the Syrian golden hamster (Mesocricetus auratus) in which lethality and disease are dependent upon both the inbred hamster strain and the LCMV strain. Young adult inbred, male and female, hamsters were tested for lethal-disease susceptibility by lymphocytic choriomeningitis virus (LCMV) strains, WE or Armstrong (ARM). With WE inocula, PD4 and MHA inbred hamsters were highly susceptible to a wasting disease. LVG and LHC inbred hamsters were intermediate in susceptibility; some of these animals died of wasting illness, and others exhibited minimal disease and survived. CB and LSH hamsters were highly resistant to any disease by WE. Mean survival times of susceptible hamsters given lethal WE inocula approximated 2.5 weeks and were not dependent on virus dose. By 1.5 weeks after WE inoculation wasting disease signs were notable and consisted of lethargy, progressive body weight loss, and diarrhea. The LCMV strain, ARM, was avirulent for all hamster strains, causing neither death nor disease. Hamsters surviving WE or ARM inoculation appeared healthy, produced LCMV antibody, and acquired resistance to further lethal WE challenge. Despite hamster-lethality differences. WE and ARM appeared comparably immunogenic for all hamster strains, based on host antibody titers. A number of other differences between the LCMV strains were, however, noted which could be relevant to virus virulence and lethality for hamster hosts. These included guinea pig lethality, temperature sensitivity, and plaque morphology.     

Genetic analyses of alloreactions between recently wild and classical inbred strains of syrian hamsters: Evidence in favor of a major histocompatibility complex

Cytotoxic alloantisera were raised between recently wild and classical inbred strains of Syrian hamsters. Antisera produced by immunizing the classical inbred strains with tissue from the partially inbred, recently wild hamsters detect several specificities shared between the classical and recently wild strains. Reciprocal mixed lymphocyte reactions between the two different groups of hamsters suggest that the new source of hamsters possesses several unique MLR phenotypes which may represent new Hm-1 haplotypes. Moreover, several recently wild strains express MLR phenotypes quite similar if not identical to the Hm-1 ^a haplotype of the inbred strain, MHA. Genetic analyses of alloreactions between domestic inbred and recently wild strains suggest that a single locus or chromosomal region encodes the allodeterminants that induce strong MLR reactivity. Six unique MLR phenotypes have been defined which most likely represent haplotypes of the hamster MHC equivalent, Hm-1. Genetic linkage studies indicate that some alloantisera detect determinants encoded by loci closely linked to the MLR locus, and therefore define Hm-1 determinants. Moreover, other alloantisera recognize determinants encoded by a locus that is unlinked to Hm-1. These studies suggest that Syrian hamsters express a polymorphic MHC equivalent, Hm-1, which encodes determinants that induce both cell-mediated and humoral alloreactivity.     

Characterization of some previously unclassified Pasteurellaceae isolated from hamsters

Bacteria isolated from purulent processes on the jaws of European hamsters (Cricetus cricetus) and from intestinal inflammatory processes in Syrian hamsters (Mesocricetus auratus), bred as laboratory animals have been shown to be phenotypically similar but not identical with Pasteurella pneumotropica. Deoxyribonucleic acid (DNA)-DNA hybridization studies indicate that with one exception, the strains represent two new species of the family Pasteurellaceae. In the absence of a close genomic relatedness to members of the genera Actinobacillus or Pasteurella or allied organisms, however, the two new taxa are described without any formal designation. The one exception was identified as Actinobacillus capsulatus, a species not previously isolated from hamsters.     

Characterization of some previously unclassified Pasteurellaceae isolated from hamsters

Bacteria isolated from purulent processes on the jaws of European hamsters ( Cricetus cricetus ) and from intestinal inflammatory processes in Syrian hamsters ( Mesocricetus auratus ), bred as laboratory animals have been shown to be phenotypically similar but not identical with Pasteurella pneumotropica . Deoxyribonucleic acid (DNA)–DNA hybridization studies indicate that with one exception, the strains represent two new species of the family Pasteurellaceae. In the absence of a close genomic relatedness to members of the genera Actinobacillus or Pasteurella or allied organisms, however, the two new taxa are described without any formal designation. The one exception was identified as Actinobacillus capsulatus , a species not previously isolated from hamsters.     

Cholesterol, bile acid, and lipoprotein metabolism in two strains of hamster, one resistant, the other sensitive (LPN) to sucrose-induced cholelithiasis

A comprehensive study of cholesterol, bile acid, and lipoprotein metabolism was undertaken in two strains of hamster that differed markedly in their response to a sucrose-rich/low fat diet. Under basal conditions, hamsters from the LPN strain differed from Janvier hamsters by a lower cholesterolemia, a higher postprandial insulinemia, a more active cholesterogenesis in both liver [3- to 4-fold higher 3-hydroxy 3-methylglutaryl coenzyme A reductase (HMG-CoAR) activity and mRNA] and small intestine, and a lower hepatic acyl-coenzyme A:cholesterol acyltransferase activity. Cholesterol saturation indices in the gallbladder bile were similar for both strains, but the lipid concentration was 2-fold higher in LPN than in Janvier hamsters. LPN hamsters had a lower capacity to transform cholesterol into bile acids, shown by the smaller fraction of endogenous cholesterol converted into bile acids prior to fecal excretion (0.34 vs. 0.77). In LPN hamsters, the activities of cholesterol 7alpha-hydroxylase (C7OHase) and sterol 27-hydroxylase (S27OHase), the two rate-limiting enzymes of bile acid synthesis, were disproportionably lower (by 2-fold) to that of HMG-CoAR. When fed a sucrose-rich diet, plasma lipids increased, dietary cholesterol absorption improved, hepatic activities of HMG-CoA reductase, C7Ohase, and S27OHase were reduced, and intestinal S27OHase was inhibited in both strains. Despite a similar increase in the biliary hydrophobicity index due to the bile acid enrichment in chenodeoxycholic acid and derivatives, only LPN hamsters had an increased lithogenic index and developed cholesterol gallstones (75% incidence), whereas Janvier hamsters formed pigment gallstones (79% incidence).These studies indicate that LPN hamsters have a genetic predisposition to sucrose-induced cholesterol gallstone formation related to differences in cholesterol and bile acid metabolism.     

Leishmania braziliensis: dissemination of Panamanian strains in golden hamsters

Dissemination of Panamanian strains of Leishmania braziliensis was observed in experimentally infected golden hamsters, Mesocricetus auratus, during the characterization of 164 strains isolated from patients (67), two species of edentates (88), and dogs (9). A total of 614 hamsters was employed in these studies. Hamsters were inoculated intradermally in the nose with 5–10 × 10⁶ promastigotes from cultures of strains in their first to third passage in vitro. Parasites were recovered by culture from skin samples, viscera, blood and bone marrow. All strains studied disseminated to various areas of the skin and to the ear pinnae. Highest incidence of dissemination occurred in the skin from the tip of the tail, feet, and ears. Positive cultures obtained from liver and spleen were not considered as evidence for metastasis since they may have been due to the transitory presence in the blood of rare parasitized macrophages. Dissemination of various areas of the body was directly proportional to the length of the postinoculation period of the sloth strains.     

山医群体近交系中国地鼠(Cricetulus griseus)的研究——Ⅰ、驯养与繁殖

经过12年工作,将野生中国地鼠驯养和近亲交配,繁育成山医群体,其中A-30家系已繁殖到22代。经遗传监测,证明20代鼠已育成近交系。文中对饲养条件、繁殖方法、近交系的建立等进行了讨论。     

Comparison of two Egyptian strains of Schistosoma mansoni in hamsters

In human infection with Schistosoma mansoni from Beni-Suef, the eggs were encountered more frequently in the urine of patients than in infection with S. mansoni from Giza, where eggs were passed into the stool. A comparative study of the two strains of S. mansoni from Beni-Suef and Giza has been carried out in golden hamster. Consistent strain differences were observed. The Beni-Suef strain proved to have lower worm recovery and different egg distribution patterns in tissues of infected hamsters. Worms of both sexes of this strain were larger in size and required a longer period to reach maturity. Hence, the prepatent period was prolonged. Significant differences between the two strains were also noted in the number of eggs per worm. A lower mortality rate and a longer survival time were encountered in hamsters infected with the Beni-Suef strain.     

Virulence of Entamoeba histolytica strains of human origin in Bombay to golden hamster

The virulence following intrahepatic inoculation to hamsters with 17 strains of Entamoeba histolytica isolated in cultures from clinical cases of amoebiasis and from asymptomatic carriers has been investigated. All 10 strains from clinical cases and four from asymptomatic carriers were found to be virulent for hamster liver, producing moderate or high grade of hepatic lesions, whereas three strains from asymptomatic carriers were found to possess low virulence with production of low grade of liver lesions. The strains from clinical cases produced marked decrease in the weight of the infected animal which was associated with high mortality. On the other hand, those from asymptomatic carriers produced minimal weight loss and low mortality.     

Immunofluorescence Staining of Group B Coxsackieviruses

Studies were conducted on the sensitivity and specificity of indirect fluorescent-antibody (FA) staining for identification of group B coxsackieviruses. Antisera produced in four different species (monkeys, rabbits, horses, hamsters) and immune ascitic fluids prepared in mice were compared for suitability in FA staining. The horse antisera showed high titers of nonspecific staining, and the rabbit antisera showed relatively low homologous FA titers. Immune reagents from monkeys, hamsters, and mice were used for homologous and heterologous testing against cell cultures infected with the various group B coxsackieviruses. Antisera or immune ascitic fluids produced in these three species showed some heterotypic and nonspecific staining at low dilutions, with the monkey antisera showing the highest heterotypic titers. However, the immune reagents could be diluted to a point where they gave no heterotypic reactivity, but still showed characteristic homotypic staining. Heterotypic staining appeared as diffuse, low-level staining of the cells, whereas homotypic staining revealed characteristic, brightly staining aggregates of viral antigen in the cytoplasm of the infected cells. By using hamster immune sera, appropriately diluted to eliminate heterotypic staining and yet give strong homotypic staining, it was possible to identify correctly 79 (93%) of 85 field strains of group B coxsackieviruses at the first passage level in BS-C-1 cells; the remainder of the strains were identified after two passages in BS-CS-1 cells. No incorrect identifications were made. A limited number of field strains of group B coxsackieviruses were passed into rhesus monkey kidney and human fetal diploid kidney cells, and these were all correctly identified by FA staining, even the strains which failed to produce a cytopathic effect in the human fetal diploid kidney cells. Two human heart and brain tissues from which coxsackievirus type B4 had been isolated failed to show homotypic FA staining in excess of nonspecific or heterotypic staining.     

Dipetalonema viteae: in vitro blastogenesis of hamster spleen and lymph node cells to phytohemagglutinin and filarial antigens

Hamsters of the randomly bred LAKZ and inbred LSH strains were infected with Dipetalonema viteae, and the in vitro responses of lymph node and spleen lymphocytes to male and female worm antigens and phytohemagglutinin (PHA) were measured by a [³H]-thymidine-uptake assay at various times after infection. The PHA response remained unchanged at the level of controls in infected LAKZ hamsters while LSH hamsters showed a depressed response to the mitogen during late infection. Stimulation of lymph node cells by filarial antigens was maximal in both strains of hamsters at Week 4 postinfection, almost reaching values obtained in PHA stimulated cultures. A similar high lymphocyte transformation reaction was measured after the injection of dead third stage larvae. During transient microfilaremia, when antibody titers reached a maximal level, the lymphocyte reactivity to filarial antigens decreased drastically and only occasionally was demonstrated in hamsters 20 and 30 weeks after infection. No correlation between lymphocyte reactivity and parasitological findings (worm load or intensity and duration of microfilaremia) could be demonstrated. The cellular unresponsiveness to filarial antigens was further analyzed in chronically infected LAKZ hamsters. No suppressor cells could be found in lymphocyte suspensions of nonresponding hamsters. A challenge infection did not restore lymphocyte reactivity. Serum of chronically infected hamsters caused marked inhibition when added to filarial antigen-sensitive lymphocytes. Lymphocytes from hamsters with a mixed D. viteae and Schistosoma mansoni infection responded as well to soluble schistosomal egg antigens at Week 30 of a D. viteae infection as lymphocytes from hamsters infected with S. mansoni alone. The humoral immune response to schistosomal antigens, however, was significantly lower in animals with a mixed infection.     

Isolation and transportation ofTreponema pertenue in golden hamsters

Ten golden hamsters of the CB/Ss LAK strain were flown to Africa, and six of them were inoculated with lesion exudate from yaws patients in an attempt to isolate newer strains ofTreponema pertenue. Three of the six hamsters developed yaws lesions from which treponemes were isolated. Two isolates have been successfully maintained in laboratory animals; these have been designated CDC isolates numbers 1 and 2. Since older stock strains may be altered through repeated animal passage, these fresh isolates will be useful in antigenic and immunological analyses of the pathogenic treponemes. This strain of golden hamster is susceptible to yaws infection, easy to care for, and shipped safely by air; therefore, they are a practical means of transportingT. pertenue.     

Ventromedial hypothalamic mediation of photoperiodic gonadal responses in male Syrian hamsters.

Short day lengths induce testicular regression in seasonally breeding Syrian hamsters. To test whether the ventromedial hypothalamus is necessary to maintain reproductive quiescence once testicular regression has been achieved, photoregressed male hamsters were subjected to lesions of the ventromedial hypothalamus (VMHx), pinealectomy (Pinx), or sham operation (Sham). VMHx hamsters underwent accelerated gonadal recrudescence compared to Pinx and Sham hamsters. Recovery of prolactin concentrations (PRL) to values characteristic of long-day hamsters was hastened in the VMHx animals compared to Sham hamsters. Concentrations of follicle stimulating hormone (FSH) increased prematurely in both the VMHx and Pinx animals, beginning a few weeks after surgery. By the time the gonads had undergone recrudescence and the hamsters were refractory to melatonin, PRL and FSH concentrations had returned to baseline long-day values in all groups; there was no evidence of hypersecretion of either hormone in any of the animals with lesions. Melatonin concentrations of VMHx hamsters did not differ from those of sham-operated animals, but because only a single determination was made, it remains possible that VMH damage altered the duration of nightly melatonin secretion. An intact VMH appears to be essential for the continued maintenance of reproductive suppression induced by exposure to short day lengths; these and earlier findings suggest that the VMH-dorsomedial hypothalamic complex mediates regression of the reproductive apparatus during decreasing day lengths of late summer and early autumn and also is necessary to sustain regression during the winter months.     

Genetical analysis and characterization of a new mutant, black tremor appearing in the Syrian hamster

A black coat-color mutant with tremor was discovered in babies of 61 generations of an inbred strain APG of Syrian hamster which had been maintained in the Nippon Institute for Biological Science, Laboratory Animal Research Station. The genetical analysis by matings between four inbred strains which had different genes in the E and B loci and four mutant strains which were introduced the mutant gene into the four inbred strains and characterization were carried out on the mutant. The results obtained are summarized as follows: 1) The mutation occurred in a different locus with E and B loci. 2) The mutant was controlled by an autosomal recessive gene designated as "bt", and it was thought that both tremor and black coat-color were the pleiotropic effect of bt gene. 3) At least one E gene in the E locus was necessary for the appearance of black coat color. Therefore, the coat-color remained cream in ee (cream) hamsters showing only trembling. 4) The degree of blackness of the coat-color of EE hamsters differed from Ee ones. The former was darker than the latter. 5) The mutant may be a useful animal model for studying abnormal myelogenesis and biosynthesis of melanin.     

Oncogenic Transformation of Hamster Embryo Cells After Exposure to Inactivated Herpes Simplex Virus Type 1

The in vitro transformation of hamster embryo fibroblasts by herpes simplex virus type 1 (HSV-1) after exposure of the virus to UV irradiation is described. Cell transformation was induced by 2 out of 12 strains of HSV-1 that were tested for transforming potential. Cells transformed by the KOS strain of HSV-1 were not oncogenic when injected into newborn Syrian hamsters. However, cells transformed by HSV-1 strain 14-012 induced tumors in 47% of the newborn hamsters injected. HSV-specific antigens were found in the cytoplasm of cells transformed by both virus strains. Sera from tumor-bearing hamsters contained HSV-1- and HSV-2-neutralizing antibodies as well as antibodies which reacted specifically with HSV antigens by the indirect immunofluorescence technique. Hamster oncornavirus antigens were not detected by immunofluorescence methods. These observations represent the first evidence of the oncogenic potential of HSV-1.     

Comparative studies of body mass,body measurements and organ weights of wild-derived and laboratory golden hamsters (Mesocricetus auratus)

All laboratory golden hamsters originate from a sibling pairing back in 1930. To investigate possible differences between domesticated and wild conspecifics, descendants of both strains were maintained under standardized laboratory conditions individually and in unisexual groups. Body mass and food consumption were monitored from birth to 22 weeks of age. The animals were subsequently sacrificed, and body measurements and body composition were analysed. In addition, the absolute and relative masses of different organs were measured. Laboratory hamsters gained more body mass through higher food consumption. However, they did not get fatter, since relative fat values were the same for both strains. Body measurements revealed only minor differences (in body and ear lengths). As deducible from the body mass, the organs (spleen, kidneys, adrenal glands, testes, epididymis and ovaries) were seen to be heavier in laboratory hamsters. Furthermore, with the exception of the kidneys, the same went for the relative values. There were distinct sexual specific differences in both strains only for body fat ( male symbol male symbol upward arrow ) and adrenal glands ( male symbol male symbol upward arrow ). In females, group housing induced an elevated level of aggression. In general, these housing conditions led to social stress symptoms, such as heavier adrenal glands. Additionally, spleen, kidneys, ovaries, body length and mass, body water and body fat were increased in group-housed hamsters. In conclusion, no major differences between laboratory and wild-derived hamsters were observed.