Biomedical subjects
Publications and source records attributed to R Klepper.
The pattern of the spongiosa in lumbar vertebrae demonstrated by ultra high resolution CT was treated statistically. Comparison of normals with osteoporotic vertebrae showed no significant difference in the large dominant trabeculae. However, there is a significant difference when quantifying the fine structures which are not to resolve lying between the larger trabeculae.
While chronic glucocorticoid treatment increases pituitary growth hormone (GH) content in rats and primates and increases pituitary GH release in response to growth hormone-releasing hormone (GHRH) in rats, it also inhibits somatic growth. We investigated these opposite actions in rats using the synthetic glucocorticoid dexamethasone. Seven days of dexamethasone treatment (40 micrograms/animal per day) did not alter the frequency of spontaneous GH pulses in conscious, freely-moving animals. The amplitude of the GH pulses in saline and dexamethasone-treated rats was different (P less than 0.01), the latter group having a higher incidence of GH levels less than 95 ng/ml, a lower incidence of GH levels between 96 and 251 ng/ml, and a higher incidence of GH values greater than 480 ng/ml. A 20 microgram/kg per day dose of dexamethasone was sufficient to significantly inhibit growth but was inadequate in enhancing the GH response to an acute injection of GHRH in anesthetized animals. These results support the concept that glucocorticoids exert their catabolic effects on somatic growth in peripheral tissues and not at the pituitary level.
A rotational field technique with a central placed block generates nearly circular isodoses with a pronounced minimum in its center, comparable with a cone-shaped mountain with a crater. The shape of both, mountain and crater, can be effectively varied by means of block size, field size, rotational angle and by superimposing two different types of rotational fields. One application of this radiation technique is the myelon-sparing treatment of the neck, another one the percutaneous completion of an intracavitary pre-radiation in the case of a gynecologic cancer.
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The two major mitogenic polypeptides for endothelial cells have been purified to homogeneity. The complete primary structure of bovine pituitary basic fibroblast growth factor (FGF) and the amino-terminal amino acid sequence of bovine brain acidic FGF have been established by gas-phase sequence analyses. Homogeneous preparations of these polypeptides are potent mitogens (basic FGF, ED50 approximately equal to 60 pg/ml; acidic FGF ED50 approximately equal to 6000 pg/ml) for many diverse cell types including capillary endothelial cells, vascular smooth muscle cells, and adrenocortical and granulosa cells; in vivo, basic FGF is a powerful angiogenic agent in the chick chorioallantoic membrane assay. The available protein sequence data demonstrate the existence of significant structural homology between the two polypeptides.
One of the major immunoreactive components of the enkephalin precursor BAM-22P in extracts of adrenal medulla is a molecule of approximately 8500 Da. A similar component is detected, after gel-permeation chromatography, in extracts of bovine plasma and in culture medium harvested from acetylcholine-stimulated bovine adrenomedullary cells in culture. Simultaneous detection of the C-terminal epitome of preproenkephalin-A: Met-enkephalin-Arg6-Phe7-OH in this secreted high-molecular-weight zone suggest that the approximately 8500-Da form of BAM-22P is the C-terminal of preproenkephalin A.
A highly specific radioimmunoassay for one of the putative adrenomedullary [Met]enkephalin precursors, BAM-12P (Tyr-Gly-Gly-Phe-Met-Arg-Arg-Val-Gly-Arg-Pro-Glu-OH), has been developed. The BAM-12P antibodies recognize the COOH-terminal fragment of the peptide from Arg7 to Glu12 and do not crossreact with [Met5]- or [Leu5]enkephalin or any of their COOH-terminal lysine or arginine extended analogs. Specificity for the COOH-terminal Glu-OH is suggested by the 100% crossreactivity with BAM-12P5-12 and 0.3% crossreactivity with BAM-12P5-12 amide. Using these antibodies, we have measured three forms of BAM-12P-like immunoreactivity in extracts of bovine adrenal medulla, of which the major form (greater than 90%) corresponds to BAM-12P by molecular weight. Extracts of bovine adrenal cortex contain 1% the amount of a BAM-12P-like material (Mr approximately 1400; 20 ng per gland), possibly due to crosscontamination with adrenomedullary tissue. The major form of BAM-12P-like material in extracts of bovine neurointermediate pituitaries is of higher molecular weight than authentic BAM-12P (Mr approximately 4000); the remaining material (10%) corresponds to BAM-12P by molecular weight. There is no detectable BAM-12P-like immunoreactivity in crude or purified extracts of bovine anterior pituitaries. Extracts of bovine hypothalamic tissues contain small amounts of BAM-12P immunoreactivity (approximately 2 ng per fragment) which can be detected as one molecular form corresponding to a 1400-dalton molecule. The results indicate that the enkephalin precursor found in the adrenal medulla also may be present in the pituitary and hypothalamus. Furthermore, the processing of this molecule appears to be tissue-specific.