Further evidence for hypothalamic asymmetry in endocrine control of the ovary.

The differential release of FSH and LH associated with hemigonadectomy (hemi-x) of prepubertal male rats can be blocked by unilateral hypothalamic deafferentation located on the side ipsilateral, but not contralateral, to the hemi-x. Also, ovarian compensatory hypertrophy (OCH) in prepubertal female rats can be blocked by ipsilateral, but not contralateral, hypothalamic hemi-islands. Both these endocrine phenomenon are limited to knife cuts on a particular side of the brain.

Chronic experimental iron losses in rats not leading to overt iron deficiency: a model for the regulation of the whole-body iron balance in an iron-replete condition.

Intestinal iron absorption studies, which include investigation of iron deficiency, increased erythropoiesis, low iron diet and acute bleeding, have been done, but none have reported the regulation of the balance of an iron-replete individual. We bled rats at regular time intervals, such that the experimentally induced iron losses were compensated by iron from storage and nutritional procurement without the onset of anemia. During these experimental periods the hemoglobin and plasma iron concentrations were determined along with repeated histochemical gradings of the bone marrow iron.

Uptake and hepatobiliary fate of two hepatocarcinogens, N,N-dimethyl-4-aminoazobenzene and 3'-methyl-N,N-dimethyl-4-aminoazobenzene, in the rat.

Two radiolabeled hepatocarcinogens, N,N-dimethyl-4-aminoazobenzene (DAB) and 3'-methyl-N,N-dimethyl-4-aminoazobenzene (3'-Me-DAB), were rapidly cleared from the blood of rats after i.v. administration, with half-lives of 40 and 70 sec, respectively.

Hepatic ligandin subunits and mRNAs during development.

Eight-week-old rats had twofold higher hepatic ligandin concentration than 10-day-old animals as determined immunologically and by steroid isomerase and glutathione S-transferase assays. Increased ligandin content was accompanied by parallel increase in subunit synthesis as determined by [3H]leucine incorporation into each subunit relative to incorporation into total cytosolic proteins. The mRNA content for each ligandin subunit was twofold higher in older animals as determined by cell-free in vitro translation followed by immunoprecipitation and dot hybridization using a ligandin cDNA probe.

Evidence for the hepatic origin of a major azo dye metabolite-binding protein from rat bile.

Small amounts of metabolite-binding protein (MBP) originally characterized from the bile were detected in rat serum and cytosol by an indirect enzyme-linked immunoabsorbant assay. The site of MBP synthesis was shown to be the liver based upon results of (1) the in vitro translation of liver poly(A)+ mRNA, followed by immunoprecipitation with anti-MBP sera and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of the immunoprecipitate, and (2) immunoprecipitation of bile collected from [3H]leucine perfused liver in situ and SDS-polyacrylamide gel electrophoresis and fluorography of the immunoprecipitate. To determine whether part of the MBP in bile is derived from the circulation, [125I]MBP was injected intravenously and bile was collected and subjected to SDS-polyacrylamide gel electrophoresis and fluorography.

Purification and characterization of a novel abundant protein in rat bile that binds azo dye metabolites and copper.

Following intravenous administration to rats of the azo dye hepatocarcinogen 3'-methyl-N,N-dimethyl-4-aminoazo-[14C]benzene, 60-70% of the injected dose was recovered in bile in 2 h. Approximately 10% of bile radioactivity was trichloroacetic acid-precipitable, not extracted by n-butanol and non-dialyzable. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of bile followed by fluorography revealed two major and several minor proteins to which radiolabelled azo dye metabolites were bound; one of these major proteins (50 kDa) was purified from bile and shown to be homogeneous by SDS-polyacrylamide gel electrophoresis, isoelectric focusing (pI 7) under denaturing conditions and N-terminal analysis.

Differential in vitro translation and independent in vivo regulation of mRNA's for subunits of ligandin.

Synthesis of both subunits (Ya and Yb) of ligandin in equal amounts was observed when poly(A)+ mRNA isolated from the post-mitochondrial fraction was translated in an in vitro wheat-germ system and the products were immunoprecipitated by monospecific antibody to ligandin and analyzed by SDS-polyacrylamide gel electrophoresis and fluorography. When the Mg2+ or K+ concentrations were increased in the in vitro wheat-germ system the ratio of synthesis of Yb/Ya subunits was 3. With a mRNA-dependent reticulocyte lysate, the synthesis of Ya subunits was 20-30% higher than Yb subunits.

Hepatocellular ligandin during N-2-fluorenylacetamide carcinogenesis.

Ligandin was decreased by 75% as determined immunologically and by glutathione-S-transferase or steroid isomerase activities in rat hepatocellular carcinomas induced by exposure to N-2-fluorenylacetamide. Minor variable differences in ligandin levels were noted between the putative, premalignant nodules induced by this regimen and normal liver.

Binding of 3'-methyl-N,N-dimethyl-4-aminoazobenzene metabolites to rat liver cytosol proteins and ligandin subunits.

Twenty min after i.p. administration of 3'-[14C]methyl-N,N-dimethyl-4-aminoazobenzene in corn oil to rats, 0.