PubMed Health⌕ Search

Biomedical subjects

J Downing

Publications and source records attributed to J Downing.

8 recordsLinked to original sources
PubMed1992

Effects of pinealectomy on wool growth and wool follicle density in merino sheep.

There is evidence to indicate that pinealectomy may enhance wool growth in the sheep. The aim of this study was to determine the effect of pinealectomy on wool growth and wool follicle density in Merino sheep. Castrated Merino rams (4 months old) were either pinealectomized (P), sham-pinealectomized (S) or not treated (C). Wool growth on mid-side patches was measured every 4 weeks and follicle density was monitored in skin biopsies collected before treatment and at regular intervals for 60 weeks. Venous blood samples were taken on each of these occasions for prolactin analysis. Melatonin concentrations were determined in venous blood collected pre- and posttreatment from samples taken over a 24-hr period during the winter solstice. Pre- and posttreatment plasma melatonin levels (mean +/- SEM) 65 +/- 17 and < 13 pg/ml for P, 86 +/- 21 and 69 +/- 20 pg/ml for S, and 94 +/- 41 and 122 +/- 37 pg/ml for C, respectively, indicated that the pineal glands had been successfully removed. Wool growth, total follicle density and liveweight (mean +/- SEM) did not differ between treatment groups. Measurements at week 60 were 3.9 +/- 0.3, 4.1 +/- 0.2, and 3.8 +/- 0.3 gm clean wool/100 cm2; 66 +/- 6, 69 +/- 7, and 64 +/- 3 follicles/mm2; and 50.4 +/- 1.3, 50.8 +/- 1.4, and 52.6 +/- 1.1 kg liveweight for groups P, S, and C, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

MKW, a novel hematopoietic antigen.

A novel hematopoietic antigen was identified using a murine monoclonal antibody raised against KG-1 cells. This antigen, termed MKW, was also detected on the surface of the monocytic cell line U937, but not on the K562, ML1, or HL-60 cell lines. On normal hematopoietic cells, the antigen is expressed on the surface of monocytic and myelocytic cells and on a subpopulation of B-cells. During normal hematopoiesis, the surface expression of MKW is greatest and occurs very early on monocytic cells. Alternatively, in myeloid cells, surface expression occurs later and cell maturation is correlated with increased surface expression. When U937 cells are induced to differentiate, surface expression is transiently up-regulated. Surface expression of MKW, however, does not appear to be an activation antigen since activation of purified T- or B-cells failed to increase MKW on the cell surface. Leukemic blasts from 22 of 80 children (27%) with acute myeloblastic leukemia and from 29 of 225 children (13%) with acute lymphoblastic leukemia expressed MKW on the cell surface. Although surface expression of MKW was absent on T-cell lines, peripheral T-cells, and most B-cells, the antigen was identified in the cytoplasm of some B-cells, T-cells, and cell lines. Immunoprecipitation studies showed that MKW is a 52-kDa protein whether expressed on the cell surface or in the cytoplasm, and it appears to be nonglycosylated. Furthermore, studies with phosphatidylinositol-phospholipase C suggested that MKW is not attached to a glycolipid anchor. The biochemical characterization of MKW and its pattern of expression are distinct from any of the previously identified CD groups or published antigens. Since this unique antigen has prognostic significance in leukemia and appears to be associated with cell differentiation, its exact role in hematopoiesis should be investigated.

Antibodies, Monoclonal↗
PubMed1992

Functional versus standardized assessment procedures: implications for educational programming.

Teacher perceptions of the educational value of two distinct assessment procedures for assessing an 8-year-old student with severe to profound multiple disabilities were compared. Direct service providers (N = 38) from a public school system, randomly distributed into three groups, were asked to use an 8-item Likert-type survey to rate one of three assessment packages: standardized, functional-ecological, and a combined package. Results for four of the eight items were statistically significant. The functional-ecological approach was perceived to be most beneficial for educational intervention. Implications for greater emphasis on a functional-ecological assessment procedure versus standardized procedures were discussed.

Activities of Daily Living↗
PubMed1991

White-black differences in cardiovascular malformations in infancy and socioeconomic factors. The Baltimore-Washington Infant Study Group.

Cardiovascular malformations were examined for white/black variation in the Baltimore-Washington Infant Study. In this population-based case-control study, cases (n = 2,087) were live births with cardiovascular malformations ascertained through pediatric cardiology centers and 53 hospitals in Maryland, the District of Columbia, and northern Virginia between 1981 and 1987. Controls (n = 2,721) were a random sample of infants from the live-birth cohort that gave rise to the cases. The proportion of infants that were white was similar for all cases as a group and controls (0.68 and 0.67, respectively). Subgroup analysis, however, revealed an excess of white infants among cases with Ebstein's anomaly (odds ratio (OR) = 3.7, 95% confidence interval (Cl) 1.1-12.5), aortic stenosis (OR = 3.6, 95% Cl 1.7-7.6), pulmonary atresia (OR = 2.5, 95% Cl 1.0-6.1), coarctation of the aorta (OR = 2.2, 95% Cl 1.4-3.5), and D-transposition of the great arteries (OR = 1.6, 95% Cl 1.1-2.5), and a deficit of white infants among cases with pulmonary stenosis (OR = 0.6, 95% Cl 0.4-0.8) and heterotaxia (OR = 0.4, 95% Cl 0.3-0.8). These associations remained when cases were stratified by infant's age or by method of diagnosis. Controlling for socioeconomic factors attenuated the white excess for Ebstein's anomaly (OR = 3.0, 95% Cl 0.9-10.5), disclosed a white excess among cases of L-transposition of the great arteries (OR = 2.8, 95% Cl 1.0-8.0), and revealed that the white excess for aortic stenosis was limited to low and middle socioeconomic strata. These results highlight racial variations in cardiovascular malformations, suggest that socioeconomic factors account for some of this variation, and identify malformation subgroups for which further evaluation of sociocultural, environmental, and familial factors is needed.

Black or African American↗
PubMed1991

Neurogenic signals regulate chromaffin cell proliferation and mediate the mitogenic effect of reserpine in the adult rat adrenal medulla.

The adrenal medulla is innervated by nerve fibers from several sources, which synapse on chromaffin cells and stimulate the secretion of catecholamines. The antihypertensive agent reserpine is known to reflexively increase this neurogenic stimulation by depleting catecholamine stores, and long-term administration of reserpine is associated with adrenal medullary hyperplasia and neoplasia. To determine the role of neurogenic signals in regulating normal and reserpine-stimulated proliferation of chromaffin cells, the incorporation of 5-bromo-2'-deoxyuridine (BrdU) into replicating nuclei was assessed in the adrenal medulla of adult rats. Unilateral adrenal denervation caused a 4-5 fold decrease in chromaffin cell labeling by 5-bromo-2'-deoxyuridine during a 2-week labeling period. Denervation also prevented stimulation of labeling in animals receiving reserpine in their diet. These findings suggest that neurogenic control of cell proliferation may play an important role in the pathogenesis of adrenal medullary hyperplasia and neoplasia, and in the normal development of the peripheral and central nervous systems.

Adrenal Medulla↗
PubMedDate not supplied

Evaluation of the preovulatory rise of follicle stimulating hormone and progesterone in normally ovulating women of reproductive age.

Sixteen normally ovulating women of reproductive age were evaluated to determine the extent of the preovulatory FSH and progesterone rise in association with the LH surge. Highly significant differences were demonstrated between the baseline and peak preovulatory levels of both FSH and progesterone (P less than .0005). These significant peak ovulatory differences of FSH and progesterone were associated with a 2.5-fold rise (mean difference of 9.06 mIU/mL) of FSH and a 3.0-fold rise (mean difference of 1.94 ng/mL) of progesterone. These small, yet very significant, preovulatory increments of FSH and progesterone are important in the ovulatory process and the formation of an adequate corpus luteum.

Adolescent↗