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A new congenic rat strain, the Dahl salt-sensitive/NIH-corpulent (DSS/N-cp) rat, has been developed to study the role of obesity and type of dietary carbohydrate in the development of hypertension and its complications. Three groups (n = 6) of young male obese and lean DSS/N-cp rats were fed diets containing either 54% sucrose, 18% sucrose plus 36% starch, or 54% starch, with 0.1% dietary sodium for 12 weeks. Regardless of the diet, obese and lean rats showed mildly elevated systolic blood pressure (SBP), being significantly higher in obese than in lean rats (SBP 156 +/- 5 mm Hg v 141 +/- 3 mm Hg, P < .05). However, SBP was not different between the three diet groups. Levels of serum insulin, triglyceride, and cholesterol as well as urinary protein excretion were significantly higher in obese than in lean rats. Obese rats fed the sucrose diets as compared to the starch diet, had higher serum insulin and lipid levels, but had lower body weights and higher serum creatinine levels. Histopathologic examination of tissues from different organs revealed a vasculopathy seen almost exclusively in obese rats fed the sucrose diets. Vascular lesions were characterized by subintimal fibrin deposition, fibrinoid necrosis, and cell proliferation with "onion skinning" in small arteries and arterioles of kidneys, intestine, pancreas, and testes.(ABSTRACT TRUNCATED AT 250 WORDS)

A new "nude" mouse model was developed by successive crossings and backcrossings between athymic nu/nu mice, on an N:NIH(S) background, and female CBA/N mice that have an X-linked immune defect in B-lymphocyte function. The resulting doubly congenic N:NIH(S(II-nu/nu mice maintained the marked thymic hypoplasia and poor development of hair of the nu/nu mice. In contrast to nu/nu and CBA/N mice, in this new mouse model both T-cell zones of lymph nodes and the spleen were depleted of lymphocytes. Lymphocytic follicles were rare and diminutive; not germinal centers were noted. The nodal cortical and paracortical areas were represented principally by connective tissue, endothelial cells, and macrophages, including giant multinucleated cells. No medullary cords were recognized. The mice with combined immunodeficiency supported the growth of human tumor xenografts and were susceptible to murine viral hepatitis.

Embryos from mice of five different genotypes were evaluated for their ability to survive cryopreservation as measured by post-thaw in vitro development. In Study 1, ovulation was induced with a standardized pregnant mares' serum gonadotropin (PMSG)/human chorionic gonadotropin (hCG) regimen, after which females were mated with males of the same genotype to produce incrossed embryos. Four- to 8-cell embryos were frozen in 1.5 M dimethyl sulfoxide (DMSO) at a rate of 0.5 degrees C/min to -80 degrees C and stored in liquid nitrogen. Following thawing at room temperature, embryos were cultured and development was evaluated 24 h later. The mean (+/- SEM) number of 4- to 8-cell embryos/pregnant female by stock/strain were: N:NIH(S), 6.8 +/- 0.8; N:NIH(S)-B, 5.8 +/- 0.5; N:GP(S), 6.5 +/- 0.6; C57BL/6N, 9.7 +/- 1.0; C3H/HeN MTV-, 9.5 +/- 0.9 (P less than 0.05). Post-thaw in vitro development was related to genetic background; the proportion of embryos culturing after thawing was: N:NIH(S), 49%; N:NIH(S)-B, 61%; N:GP(S), 66%; C57BL/6N, 75%; C3H/HeN MTV-, 56% (P less than 0.05). Study 2 was conducted to evaluate the influence of mating various females to males of a genotype known to have a lower post-thaw embryo survival rate. N:NIH(S)-B, N:GP(S), C57BL/6N, and C3H/HeN MTV- female mice were mated with N:NIH(S) males to produce hybrid embryos. Post-thaw embryo survival was reduced (P less than 0.05) in three of the four hybrid groups. Fresh incrossed and hybrid embryos from each study were cultured for 24 h and yielded culture rates ranging from 95% to 99% (P greater than 0.05) among all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

C-type virus particles were observed by electron microscopy in cultures of a cell line (NML-1) derived from a lymphosarcoma that arose spontaneously in a nude NIH outbred mouse. The presence of such particles indicated that human tumors heterotransplanted in nude mice might become contaminated with murine oncornaviruses.