Cytokine regulation of prethymic T-lymphoid progenitor-cell proliferation and/or differentiation has not been well-defined, although much is known of cytokine regulation of hemopoietic stem- and progenitor-cell development. Here we use a recently identified hemopoietic growth factor, stem-cell factor (SCF) (a form of the c-kit ligand), and a transplant model of thymocyte regeneration to assess ...

We hypothesized that administration of estradiol benzoate to males and testosterone propionate to female neonatal rat pups alters sex-specific ventilatory responses to aspartic acid with correspondent changes in N-methyl-D-aspartate receptor subunit 1 (NR1) expression determined by Western blot in specific brain regions. One-day-old rat pups received estradiol benzoate, testosterone propionate,...

Details are presented of a technique for maintaining adult liver parenchymal cells in culture in a nonproliferating state. Hepatic regenerative stimulator substance (SS), prepared from weanling rat liver, will stimulate tritiated thymidine incorporation into liver DNA when injected into another rat or mouse. Preliminary experiments are presented which show that SS stimulates non-proliferating a...

Reason for the higher retention of 137Cs in the suckling than in the weanling rat was investigated. Rat pups, which were given 137Cs pre viously, were divided into two groups at 21 days of age, i.e., at the normal weaning age. One group weaned to the usual solid diet at this age, whereas the other group was kept under breast-feeding for one to two weeks longer beyond this normal weaning time. T...

Acid-Base Balance and Sodium-to-Chloride Ratio in Diets of Laying Hens. Israel Cohen, Shmuel Hurwitz and Arie Bar 1 Fiber Digestion in the Beaver. W. H. Hoover and S. D. Clarke 9 Methylmalonate, Formiminoglutamate and Aminoimidazolecarboxamide Excretion of Vitamin Bu-deficient Germfree and Conventional Rats. Susan M. Oace and Jane M. Abbott 17 Influence of Amino Acid Level in the Diet upon Amin...

Thirty-five female Sprague-Dawley weanling rats were fed 5-acetamido-3-(5-nitro-2-furyl)-6H-l ,2,4-oxadiazine for 37 weeks. All 32 rats surviving 28 weeks or more developed hemangioendothelialsarcomas at one or more sites. These unusual tumors were located in the livers of 31 rats, in the mesentery of 30 rats, and in the lungs of 5 rats. Nine rats developed alveolar carcinomas, and 1 rat develo...

The relative toxicity of low doses of lead acetate provided steadily in drinking water or by mouth once per week was studied in weanling and adult rats. Free erythrocyte protoporphyrin and urinary delta-aminolevulinic acid levels were measured, as well as lead levels in blood and kidney. The accumulation of lead in brain tissue and in bone (femur) was measured to determine the effect of age and...