In an attempt to isolate virus particles, a hamster macrophage cell line was examined by electron microscopy. This cell line was established from hamster macrophages infiltrating human lymphoid cells heterotransplanted in Syrian hamsters. The cultured cells appeared to be macrophages, containing round smooth nuclei with clear nucleoli, and numerous cytoplasmic primary lysosomes, polysomes, and ...

Renal carcinoma in male Syrian hamsters, induced by chronic admin istration of estradici for 5-7 months, is known to arise in the cortex at the cortico-medullary junction. In this in vivo model for hormonal carcinogenesis, estrogen-induced covalent DNA adducts have previously been observed in whole kidney and have been postulated to be involved in tumor induction. In the present study, the intr...

Male Sprague-Dawley rats were fed control diet or diet containing 0.05% nafenopin (NAF) or 0.025% WY-14,643 (WY) and male Syrian hamsters were fed control diet or diet containing 0.25% NAF or 0.025% WY for periods of 1, 15, 40, and 60 weeks. Both NAF and WY produced a sustained increase in liver weight and induction of peroxisomal fatty acid beta-oxidation in the rat and Syrian hamster. Replica...

Renal carcinoma in male Syrian hamsters, induced by chronic administration of estradiol for 5-7 months, is known to arise in the cortex at the cortico-medullary junction. In this in vivo model for hormonal carcinogenesis, estrogen-induced covalent DNA adducts have previously been observed in whole kidney and have been postulated to be involved in tumor induction. In the present study, the intra...

The virus of lymphocytic choriomeningitis produces an intense systemic infection in Syrian hamsters with few if any clinical and pathological signs of disease. Specific soluble antigen is demonstrable in the spleen of infected animals until about the 14th day when antisoluble substance antibodies make their appearance. Circulating virus disappears after the 4th week and neutralizing antibodies ...

UV irradiation of African green monkey cells greatly stimulated efficiency of simian virus 40 induction from simian virus 40-transformed Syrian hamster cells after cell fusion. The maximum inducing activity was observed at 15 to 20 h after irradiation but remained only transiently. The addition of cycloheximide after UV irradiation eliminated the stimulation of the activity.

Fatty acid metabolites such as prostaglandins are important regulators of DNA synthesis and cell proliferation. However, the mechanisms involved in this regulation are unclear. We have examined the effects of several fatty acid metabolites on the expression of the growth-related genes c-jun and jun-B in Syrian hamster embryo cells. Treatment of cells with prostaglandin E2 (PGE2) resulted in the...

The cyclic nucleotides, cyclic adenosine 3':5'-monophosphate (cAMP) and cyclic guanosine 3':5'-monophosphate (cGMP) or their dibutyryl and monobrominated derivatives, may either increase or decrease morphological transformation of Syrian hamster embryo cells exposed to N-methyl-N'-nitro-N'-nitrosoguanidine (MNNG). The effect on transformation is primarily a function of the parent cyclic nucleot...

Seasonally breeding mammals rely on the photoperiodic signal to restrict their fertility to a certain time of the year. The photoperiodic information is translated in the brain via the pineal hormone melatonin, and it is now well-established that it is the variation in the duration of the nocturnal peak of melatonin which synchronizes reproduction with the seasons. The Syrian hamster is a long ...

Fatty acid metabolites such as prostaglandins are important regulators of DNA synthesis and cell proliferation. However, the mechanisms involved in this regulation are unclear. We have examined the effects of several fatty acid metabolites on the expression of the growth-related genes c-jun and jun-B in Syrian hamster embryo cells. Treatment of cells with prostaglandin E2 (PGE2) resulted in the...