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Biomedical subjects

D Powell

Publications and source records attributed to D Powell.

At least 217 records · Page 12Linked to original sources
PubMed1971

Parathyroid hormone: secretion and metabolism in vivo.

Gel filtration and radioimmunoassay were used to determine the molecular size and immunochemical reactivity of parathyroid hormone present in gland extracts, in the general peripheral circulation, and in parathyroid effluent blood (obtained by venous catheterization) from patients with hyperparathyroidism, as well as from calves and from cattle. Hormone secreted in vivo from normal bovine parathyroid glands and from human parathyroid adenomas is similar in size to the 84-amino-acid peptide (molecular weight of 9500) extracted from the parathyroids. However, much of the immunoreactive parathyroid hormone present in the peripheral circulation of man and cattle is smaller than the extracted or secreted hormone; it elutes from gel columns at a position corresponding to a molecular weight of about 7000. The immunological characteristics of extracted and secreted hormone are identical, while hormone in the general circulation is immunologically dissimilar to extracted and secreted hormone. The results indicate that parathyroid hormone secreted from the parathyroids in man and cattle is at least as large as the molecule extracted from normal bovine glands. However, once secreted into the circulation the hormone is cleaved, and one or more fragments, immunologically dissimilar to the originally secreted hormone, constitute the dominant form of circulating immunoreactive hormone.

Amino Acids↗
PubMedDate not supplied

Therapeutic studies in NZB/NZW F1 mice. V. Comparison of cyclophosphamide and chlorambucil.

Cyclophosphamide (Cy) has been demonstrated to be effective in treating autoimmune disease in NZB/NZW F1 mice. This study was designed to compare the efficacy of chlorambucil (Chlor) with that of a known effective drug (Cy) in the treatment of murine lupus. NZB/W female mice were treated with Cy, Chlor, or nothing on a once-a-month dosage schedule. The age of onset of proteinuria, the severity of glomerular lesions, and the median survival were compared among the three treatment groups. Cy was found to be superior to Chlor and controls in all measures.

Animals↗
PubMedDate not supplied

Expression of rat L-FABP in mouse fibroblasts: role in fat absorption.

Fatty acid-binding proteins (FABP) are abundant cytosolic proteins whose levels is responsive to nutritional, endocrine, and a variety of pathological states. Although FABPs have been investigated in vitro for several decades, little is known of their physiological function. Liver L-FABP binds both fatty acids and cholesterol. Competitive binding analysis and molecular modeling studies of L-FABP indicate the presence of two ligand binding pockets that accommodate one fatty acid each. One fatty acid binding site is identical to the cholesterol binding site. To test whether these observations obtained in vitro were physiologically relevant, the cDNA encoding L-FABP was transfected into L-cells, a cell line with very low endogenous FABP and sterol carrier proteins. Uptake of both ligands did not differ between control cells and low expression clones. In contrast, both fatty acid uptake and cholesterol uptake were stimulated in the high expression cells. In high expression cells, uptake of fluorescent cis-parinaric acid was enhanced more than that of trans-parinaric acid. This is consistent with the preferential binding of cis-fatty acids to L-FABP but in contrast to the preferential binding of trans-parinaric acid to the L-cell plasma membrane fatty acid transporter (PMFABP). These data show that the level of cytosolic fatty acids in intact cells can regulate both the extent and specificity of fatty acid uptake. Last, sphingomyelinase treatment of L-cells released cholesterol from the plasma membrane to the cytoplasm and stimulated microsomal acyl-CoA: cholesteryl acyl transferase (ACAT). This process was accelerated in high expression cells. These observations show for the first time in intact cells that L-FABP, a protein most prevalent in liver and intestine where much fat absorption takes place, may have a role in fatty acid and cholesterol absorption.

Animals↗