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Caffeine-mediated changes of sex ratio in Chinese hamsters, Cricetulus griseus.

Sixty 6- to 10-week-old male Chinese hamsters were assigned to two groups. In one, the animals were untreated and in the other, they were treated with 0.02 g caffeine/100 ml water orally for 60 days. The sex ratio of the resulting litters showed a significant (P smaller than 0.025) skewing towards females (61.4%) when compared to that of the controls (49.2%).

Administration, Oral

[On the simultaneous effects of ionising radiation and chemical agents on animal cells. 1st communication. Cytogenetic studies on X-rays and isonicotinic acid hydrazide in the Chinese hamster, Cricetulus griseus (author's transl)].

In bone marrow cells of Chinese hamsters enhanced chromosome damage is observed after 48 h treatment of the animals with isoniazid (INH) combined with X-rays only at much higher doses than normally applied in human therapy. Compared to X-ray-induced aberration levels, 125 mg/kg INH and 50 R given simultaneously increase the number of gaps and breaks, the latter being increased over-additively. This points to an interaction between both agents. The combined treatment changes the mitotic rate of the bone marrow as well.

Animals

[Simultaneous effect of 5-bromodeoxyuridine and cysteamine on x-irradiated diploid cells of Chinese hamster, Cricetulus griseus, in vitro].

Cells of the Chinese hamster line B 14 FAF 28 were treated with BUdR and irradiated with X-rays under the presence of cysteamine. The dose-dependent inactivation rates could be determined rather precisely by marking single cells. Daily cell counts in the growing colonies made it possible to establish individual colony growth curves. The results of both analyses show for untreated and treated cells a nearly equal factor with respect to the protecting effect of cysteamine. Also in the "macrocolonies" this effect is clearly measurable even five days after irradiation indicating a still existing very different vitality of the cells at that time. The results are discussed with concern to following irradiations.

Animals

Observations on the synaptonemal complex in Armenian hamster spermatocytes by light microscopy.

Using the silver staining technique, in somatic and meiotic chromosomes of the Armenian hamster (Cricetulus migratorius), it is possible to stain synaptonemal complexes (SCs) and the nucleolus organizer regions (NORs) in early spermatocytes. There are five pairs of autosomes (Nos. 2, 4, 6, 7, and 8) which have terminally located NORs. Synaptonemal complexes and accessory structures present in the sex chromosomes within the sex vesicle can be easily observed using light microscopy.

Animals

Behavioral development in three hamster species.

The preweaning behavioral development was compared in 3 hamster species: the golden (Mesocricetus auratus), Chinese (Cricetulus griseus), and Djungarian (Phodopus sungorus). Differences in the age of appearance of action patterns could not be summarized by simply ranking species on either precocity or developmental speed, nor were they eliminated by measuring age from conception. Problems in the interpretation of species differences in the age of appearance of action patterns are discussed.

Adaptation, Biological

Effects of various cyclophosphamide concentrations in vivo on sister chromatid exchanges (SCE) and chromosome aberrations of Chinese hamster bone marrow cells: comparison of two methods measuring the mutagenicity of a test compound.

The in vivo SCE formation and the induction of chromosome aberrations in the bone marrow of Chinese hamsters (Cricetulus griseus) were studied after various concentrations of cyclophosphamide, and the sensitivity of the two test methods was compared. The administraiton of 1.0, 5.0, 13.3, 25.0, and 40.0 mg/kg body weight induced a dose-dependent increase in SCE. The frequency of chromosome aberration, however, was not increased significantly with doses of 1.0 and 5.0 mg/kg body weight. Only with doses of more than 13.3 mg is a significant induction of chromosome aberrations seen. Therefore the SCE test system seems to be 10 times more sensitive than the induction of chromosome aberrations in the same cell type.

Animals

Carcinogenic effects of different nitroso-compounds in Chinese hamsters. II. N-nitrosomorpholine and N-nitrosopiperidine.

A total of 320 Chinese hamsters (Cricetulus griseus) (CH) were subcutaneously (s.c.) treated with 1/5, 1/10, or 1/20 LD50 of N-nitrosomorpholine (NM) or N-nitrosopiperidine (NP). In the CH, NM and NP both produced up to a 100% rate of papillomas of the cheek pouch, tongue, pharynx, esophagus and forestomach. Occasionally squamous cell carcinomas also developed in these organs. A high rate of hepatomas was realized by NP.

Animals

Carcinogenic effects of different nitroso-compounds in chinese hamsters: N-dibutylnitrosamine and N-nitrosomethylurea.

Three hundred and twenty Chinese hamsters (Cricetulus griseus) (CH) were subcutaneously (s.c.) treated with 1/5, 1/10 or 1/20 the mean lethal dose (LD50) of N-dibutylnitrosamine (DBN) or N-nitrosomethylurea (NMU). In several respects these two substances produced the same organotropy in the CH as in the Syrian golden (SGH) and European hamsters (EH). DBN prolonged lung tumours and neoplasms of the injection site. NMU induced tumours of the injection site only.

Animals

Carcinogenic effects of different nitroso-compounds in Chinese hamsters. I. Dimethylnitrosamine and N-diethylnitrosamine.

Three hundred and twenty Chinese hamsters (Cricetulus griseus) (CH) were treated (s.c.) with 1/5, 1/10 or 1/20 LD50 of dimethylnitrosamine (DMN) or N-diethylnitrosamine (DEN). These substances, in several respects, showed a different organotropy in this species than in both the Syrian golden (SGH) and the European hamster (EH). In CH, DEN produced up to 100% squamous cell papillomata and occasionally also carcinomata of the cheek pouch, tongue, pharynix, oesophagus and forestomach. With DEN a high rate of hepatomata was simultaneously realized. DMN induced a considerable quantity of liver tumours, the highest incidence being demonstrated in the lowest dosage group.

Animals

Laboratory studies of a lymphocytic choriomeningitis virus outbreak in man and laboratory animals.

Investigation of an outbreak of prolonged febrile illness in medical center personnel at the University of Rochester School of Medicine and Dentistry revealed lymphocytic choriomeningitis (LCM) virus to be the causative agent. Syrian or golden hamsters (Mesocricetus auratus) were found to be the only animals involved in maintaining the virus and were the source of human infections. Isolations of LCM virus were made from autopsy specimens of 13 of 46 (28%) golden hamsters. Virus isolations were made from 22 of 28 (79%) frozen specimens of 11 tumor lines transplanted repeatedly in golden hamster cheek pouches. No virus isolations were made from 86 autopsied laboratory mice, laboratory rats, Chinese hamsters (Cricetulus griseus), or laboratory rabbits or from 10 tumor cell lines transplanted in laboratory mice. Complement-fixation testing of 301 animal sera from the vivarium also revealed involvement primarily of golden hamsters. The probable source of virus introduction into the Rochester facilities was found to be two LCM-contaminated tumor lines sent from a biological supplier to Rochester in 1969.

Animals

The kinetics of contact inhibition in mammalian cells.

To elucidate the process of contact inhibition in mammalian cells, we investigated the kinetics of growth arrest in [3H]thymidine labelled embryonic chinese hamster (Cricetulus griseus L.) cells after the addition of various concentrations of unlabelled cells. It was observed that after the contact inhibition concentration had been reached, the cells grew undisturbed for one more generation. In the following 24 hr the concentration fell back to the level at the beginning of the experiment and stayed there.

Animals