Availability of metabolic fuels controls estrous cyclicity of Syrian hamsters

Food deprivation and weight loss inhibit ovulation and estrous behavior in Syrian hamsters. In the present experiments, lean hamsters were more susceptible to starvation-induced anestrus than fat hamsters. However, anestrus was not caused by changes in any dimension of body size per se, but instead by the availability of metabolic fuels. Simultaneous pharmacological blockade of both fatty acid oxidation and glycolysis inhibited reproduction, but, as long as one of these metabolic pathways could be used, estrous cycles continued. Thus, reproduction in female Syrian hamsters is sensitive to the general availability of oxidizable metabolic fuels.     

红葡萄酒对金黄地鼠血浆脂质水平的影响

 【目的】探讨红葡萄酒对动脉粥样硬化的保护作用及其可能机制。【方法】选用50只雄性金黄地鼠，随机分为红葡萄酒组、红葡萄酒脱酒精样组、酒精组、高血脂组和对照组。在试验的4周内，除对照组饲喂基础饲料外，其余各组饲喂高脂饲料，处理组以15 ml•kg-1体重进行灌胃。第4周末，取金黄地鼠血浆测定血脂指标，脂质过氧化产物丙二醛含量，同时对肝组织进行电镜观察。【结果】与高脂组比，红葡萄酒组、红葡萄酒脱酒精样组和酒精组金黄地鼠血浆总胆固醇和甘油三酯的水平极显著降低。各处理组血浆低密度脂蛋白胆固醇、极低密度脂蛋白胆固醇水平极显著降低，但高密度脂蛋白胆固醇没有表现出显著性差异。载脂蛋白A1和载脂蛋白B各处理组与高脂组比较，没有显著性差异。各处理组肝脏指数显著降低。红葡萄酒组、红葡萄酒脱酒精样组和酒精组金黄地鼠血浆丙二醛值显著降低。【结论】红葡萄酒可以预防动脉粥样硬化的发生。     

INHIBITION BY 5-IODODEOXYURIDINE OF THE ONCOGENIC EFFECTS OF ADENOVIRUS TYPE 12 IN HAMSTERS

Subcutaneous tumors induced in newborn hamsters by type 12 adenovirus were suppressed when 0.5 mg of 5-iodo-2'-deoxyuridine (IUdR) was given at the same subcutaneous site as the virus. Although one injection of IUdR given immediately after the virus was effective, additional injections on subsequent days reduced further the number of hamsters developing tumors. These effects of lUdR are especially interesting since replication of infectious adenovirus 12 cannot be demonstrated in the hamsters at any time before or after tumor development.     

The Influence of Red Wine on Lipid of Golden Hamsters Plasma

This experiment was conducted on 50 male golden hamsters, which were divided into five groups. Each group contained 10 hamsters： red wine group, alcohol-free red wine group, alcohol group, hypedipidemia group, and control group. During the four-week regime, all the hamsters were fed with a high cholesterol diet, except the control group. After completion of the trial, the plasma lipid levels and lipid peroxidation contents were determined in the golden hamsters, and the morphological variation in liver cells was investigated with electron microscopy. The results showed that concentrations of TC and TG in red wine, alcohol-free red wine, and alcohol groups had decreased dramatically. Compared with the hyperlipidemia group, the levels of LDL-C had significantly decreased in other groups, but not the HDL-C. Consumption of red wine, alcohol-free red wine, and alcohol, had no significant effects on Apo A1 and Apo B. Red wine, alcohol-free red wine, and alcohol significantly decreased the contents of MDA in hamsters. The experiment demonstrated that red wine could ameliorate the incidence of atherosclerosis （AS） via reducing serum TC, TG, LDL-C, and the compounds in red wine had synergic effects.     

Cardiac atria of BIO 14.6 hamsters are deficient in natriuretic factor

The hearts of 220-day-old hamsters of the BIO 14.6 strain are deficient in atrial natriuretic factor; saline extracts of atria produce one-third the natriuretic and diuretic effects of extracts of atria from age-matched normal hamsters. BIO 14.6 hamsters are known to develop congestive heart failure with edema when they are about 200 days old, and the venous congestion and edema are preventable by parabiosis with normal hamsters. The humoral mediator, the deficiency of which causes venous congestion and edema in BIO 14.6 hamsters, may be atrial natriuretic factor.     

Lymphocytic-choriomeningitis virus in hamster tumor: spread to hamsters and humans

A passage line of a spontaneous hamster fibrosarcoma is contaminated by the virus. of lymphocytic choriomeningitis. Tumors from animals receiving implants when newborn contain high titers of infectious lymphocytic-choriomeningitis virus and complement-fixing antigen, and hamsters receiving implants when weanlings develop high titers of complement-fixing antibody against lymphocytic-choriomeningitis virus. In contrast with the specific reactions of tumorous hamsters to the initiating virus in virus-induced tumors, the development of complement-fixing antibody to lymphocytic-choriomeningitis virus does not depend on the development of tumors. Infant hamsters bearing the tumor have a generalized subclinical infection and seem able to spread virus to other hamsters and to humans.     

Melatonin induction of gonadal quiescence in pinealectomized Syrian hamsters

Pinealectomized Syrian hamsters were injected thrice daily with 25 micrograms of melatonin per injection. The injections were administered at 3-hour intervals either during the day or during the night of a photoperiodic cycle of 14 hours of light and 10 hours of darkness. After 6 weeks of treatment with melatonin during the night, both pinealectomized and intact hamsters had reduced testis weight, and pinealectomized hamsters showed decreased levels of serum gonadotropins. Injection of melatonin during the day for 7 weeks either once (75 micrograms) a day or thrice (25 micrograms per injection) daily caused a reduction in testis weight in pinealectomized hamsters. Both pinealectomized and intact females injected with melatonin thrice daily during the day became anovulatory by week 7 of treatment. These results are similar to those observed when hamsters are exposed to a short photoperiod, suggesting that melatonin may be acting as a hormone in mediating the effects of photoperiod on the reproductive system of the Syrian hamster.     

Multiple circadian oscillators regulate the timing of behavioral and endocrine rhythms in female golden hamsters

A single daily "surge" in pituitary luteinizing hormone release was observed in ovariectomized-estrogen-treated hamsters expressing an intact circadian rhythm of locomotor activity. In contrast, two luteinizing hormone surges occurred within a single 24-hour period in hamsters whose activity rhythm had dissociated or "split" into two distinct components. These observations indicate that both behavioral and endocrine circadian rhythms are regulated by the same multioscillator system, which seems to be composed of at least two distinct circadian oscillators.     

THE GOLDEN HAMSTER (CRICETUS AURATUS) AS A TEST ANIMAL FOR THE DIAGNOSIS OF LEPTOSPIROSIS

There is evidence that the golden hamster (Cricetus auratus) is the animal of choice for the isolation of leptospirae, especially of the Leptospira canicola type since young guinea pigs and mice are resistant to infection and rats are entirely refractory. Both the classical strain, L. icterohaemorrhagiae and L. canicola on isolation have been found to produce a fatal infection in hamsters. The present report deals with the isolation of L. canicola in two instances by the injection intraperitoneally into hamsters of urine obtained from dogs ill with suspected leptospirosis. Each of the dogs was apparently the source of infection for a human case of Canicola leptospirosis. The classical strain L. icterohaemorrhagiae was isolated from the dog for the first time in the United States. In this instance the organism was isolated by injecting both whole blood and urine from the patient intraperitoneally into young hamsters. The injection into hamsters of suitable material from patients infected with L. canicola and L. icterohaemorrhagiae is followed by a fatal leptospirosis in the test animal.     

Photoperiodic control of hamster testis

The response of the testes of juvenile and adult hamsters to various photoperiods was examined. The testes of juvenile animals reached maturity regardless of the light cycle on which the animals were raised. However, the testes of adult hamsters required at least 12.5 hours of light per day to maintain spermatogenesis and prevent degeneration. This is one of the few demonstrations of a response suitable for study in investigations of the photoperiodic control of testicular function in a laboratory mammal.     

Estradiol shortens the period of hamster circadian rhythms

Continuous administration of estradiol benzoate by means of subcutaneously implanted capsules shortened the free-running circadian period of locomotor activity of blind hamsters (Mesocricetus auratus) that had had their ovaries removed. Estradiol also advanced the phase of the wheel running of sighted female hamsters without ovaries that were entrained to a photoperiod with 12 hours of light and 12 of darkness. These results, and findings from hamsters undergoing natural estrous cycles, indicate that endogenous estradiol is involved in the regulation of circadian periodicity.     

Adenovirus tumorigenesis: role of the viral genome in determining tumor morphology

Adenovirus type 12 transforms the fibroblastic BHK21 (baby hamster kidney) cell line into rounded or cuboidal cells that give rise in hamsters to undifferentiated small cell sarcomas indistinguishable from those induced in newborn hamsters by inoculation of the virus itself. In contrast. cells from this line transformed by polyoma virus retain their fibroblastic morphology and induce fibrosarcomas in hamsters. This suggests that the morphology of tumors induced by the adenovirus-transformed cells from this line may be determined by the viral genome and that such mechanism may also explain the remarkably uniform microscopic appearance which seems to characterize tumors induced in hamsters by direct inoculation of adenovirus type 12.     

Calcium antagonist receptors in cardiomyopathic hamster: selective increases in heart, muscle, brain

The Syrian cardiomyopathic hamster has a hereditary disease in which a progressive myocardial necrosis mimics human forms of cardiac hypertrophy. Lesions are associated with calcium overload and can be prevented with the calcium antagonist verapamil. Numbers of receptor binding sites for calcium antagonists in heart, brain, skeletal muscle, and smooth muscle were markedly increased in cardiomyopathic hamsters. The uptake of calcium-45 into brain synaptosomes was also increased in cardiomyopathic hamsters. The increase in calcium antagonist receptors and related voltage-sensitive calcium channels may be involved in the pathogenesis of this cardiomyopathy.     

Leukotactic factor elaborated by mixtures of genetically dissimilar cells

Mixtures of immunologically competent cells, from genetically dissimilar donors from inbred strains of mice, rats, or Syrian hamsters, cultivated in vitro elaborate into the medium a factor capable of attracting polymorphonuclear cells when it is injected into the skin of irradiated hamsters. Supernatant medium of cultured node cells from genetically identical donors contains no leukotactic activity. The degree of the cell accumulation seemed to parallel closely the degree of histoincompatibility.     

Outbreak of poliomyelitis in Hispaniola associated with circulating type 1 vaccine-derived poliovirus

An outbreak of paralytic poliomyelitis occurred in the Dominican Republic (13 confirmed cases) and Haiti (8 confirmed cases, including 2 fatal cases) during 2000-2001. All but one of the patients were either unvaccinated or incompletely vaccinated children, and cases occurred in communities with very low (7 to 40%) rates of coverage with oral poliovirus vaccine (OPV). The outbreak was associated with the circulation of a derivative of the type 1 OPV strain, probably originating from a single OPV dose given in 1998-1999. The vaccine-derived poliovirus associated with the outbreak had biological properties indistinguishable from those of wild poliovirus.     

Living with disease? Biosecurity and avian influenza in ostriches

This paper is about an avian influenza outbreak in South Africa’s commercial ostrich industry. The outbreak was managed according to international best practice and led to the destruction of 30,000 ostriches in two of South Africa’s provinces. However, the industry has a long history of managing low pathogenic avian influenza outbreaks in a different way. We use the 2004 outbreak and earlier approaches to managing disease to shed light on recent debates on how we might live differently with livestock diseases. The paper is based on in-depth interviews with farmers, veterinarians, scientists and agriculture officials.     

猪带绦虫仓鼠动物模型的建立

 【目的】为开展猪带绦虫的病原学形态观察、生物学特性研究以及解决实验材料来源的问题,建立猪带绦虫的实验仓鼠动物模型。【方法】通过经口感染被免疫抑制的实验仓鼠,观察仓鼠体内绦虫的感染、生长发育及寄生部位等生物学特性,并利用压片技术和组织切片技术对检出的绦虫的形态结构进行研究。【结果】免疫抑制剂在5 mg/只,感染一次就能使囊尾蚴发育到性成熟;在实验仓鼠体内,感染后40 d的仓鼠体内就能检出具有体节的可见虫体,感染80 d后的仓鼠体内能检出孕卵节片;检出的虫体多数吸附在小肠前1/3段,也有寄生在胆囊和胆管中的虫体,甚至偶见虫体钻出胆囊外堆积在肝脏附近;虫体头节上可见4个吸盘及两圈小钩;与人猪带绦虫相比,成熟节片较少。【结论】成功建立了猪带绦虫仓鼠动物模型,这使得成功解决猪带绦虫实验材料的来源问题成为可能,也为猪带绦虫的深入研究奠定了基础。     

Virus-induced hydrocephalus: development of aqueductal stenosis in hamsters after mumps infection

Hydrocephalus developed as a sequela of mumps virus infections of suckling hamsters. The initial infection after intracerebral inoculation was limited largely to ependymal cells lining the ventricles. This infection was clinically inapparent but later resulted in a noninflammatory stenosis or occlusion of the aqueduct of Sylvius.     

RNA metabolism in tracheal epithelium: alteration in hamsters deficient in vitamin A

The electrophoretic pattern of RNA molecules that are synthesized in vitro in tracheal epithelium from hamsters deficient in vitamin A differs from that of RNA synthesized in normal, pair-fed control hamsters. There is less RNA of low electrophoretic mobility in the epithelial cells deficient in vitamin A. This alteration is reversed after the deficient animals have been treated with vitamin A.     

山银花主要病虫发生与海拔高度相关性初探

为探索不同海拔高度的山银花病虫害发生规律。为综合防治山银花病虫害提供依据,通过调查不同海拔高度危害山银花植株的胡萝卜微管蚜、白粉痛、尺蠖发生程度,探讨山银花主要病虫发生程度与海拔高度之间的相关性。调查结果显示：在所调查的海拔高度内。白粉病的病情指数随着海拔高度的升高而增长,4—5月生长在海拔430m地带的山银花植株白粉病发生严重。胡萝卜微管蚜在所调查的各个海拔高度均有分布,1-3月在海拔290m-350m之间发生较重、4月份在海拔320-430m之间发生较重;5—6月发生逐渐减轻。山银花尺蠖在夏梢期对叶片的危害随着海拔的升高而减轻。结果表明：山银花主要病虫发生与其所处的海拔高度存在一定的相关关系。