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Biomedical subjects

R Green

Publications and source records attributed to R Green.

At least 397 records · Page 22Linked to original sources
PubMed1983

Folate status in patients receiving maintenance doses of sulfasalazine.

Hematologic studies, including serum and RBC folate assays, were done on 45 outpatients with chronic colitis who either took sulfasalazine (n = 27) or did not use it (n = 18). Overall, sulfasalazine users and nonusers had similar mean hemoglobin, hematocrit, serum folate, and RBC folate levels. However, within the drug users, RBC folate was inversely correlated with drug dose; serum folate was not. Patients taking 2 g or more of sulfasalazine daily had lower mean RBC folate levels (221.2 +/- 27.3 ng/mL) than patients either taking less (371.7 +/- 35.0 ng/mL) or nonusers (330.3 +/- 30.3 ng/mL). Mean corpuscular volume was also related to drug dose but not to RBC folate. Although maintenance sulfasalazine use rarely causes clinically significant folate deficiency, subclinical tissue depletion occurs as a dose-related effect.

Colitis↗
PubMed1983

Inhibition of macrophage tumoricidal activity by immune complexes and altered erythrocytes.

Engagement of the macrophage membrane by biologic particles including insoluble immune complexes inhibited the development of lymphokine-mediated nonspecific tumoricidal activity by murine macrophages. The degree of inhibition was dependent on the dose of particles and the lymphokine concentration. Inhibition was not due to macrophage cell death or to diminution of cell adherence after ingestion of the immune complexes. Soluble immune complexes were not inhibitory, although approximately 10% of the complexes became cell-associated. Monomeric or heat-aggregated IgG was also not inhibitory. IgG-opsonized erythrocytes (EA) were inhibitory and inhibition was dependent on the degree of opsonization. In contrast, nonopsonized erythrocytes (E), which did not bind to macrophages, were not inhibitory. Phagocytosis of glutaraldehyde-treated E or E carrying IgM antibody and complement (EAC) also led to a reduction of tumorilytic activity. Insoluble immune complexes were inhibitory when added either before or after lymphokine. Phagocytosis was neither sufficient nor necessary to cause inhibition because 1) ingestion of polystyrene latex beads did not diminish tumoricidal activity, and 2) macrophages plated on IgG-coated surfaces were inhibited with respect to the tumoricidal function. Inhibition was not affected when indomethacin (10(-6) M) was included in the assay, which indicated that prostaglandins were not involved in the process. Thus, macrophage tumoricidal responsiveness may be compromised by interaction of biologic substances with macrophage plasma membranes. This process may thereby inactivate an important host defense mechanism against neoplastic cells.

Animals↗
PubMed1982

Ninety-nine "tomboys" and "non-tomboys": behavioral contrasts and demographic similarities.

Two samples of female children with diverse patterns of sex-typed behaviors are described. Fifty traditionally sex-typed and 49 nontraditionally sex-typed girls are contrasted. Their age range is 4-12 years. They are widely divergent on sex-typed preferred toys, gender of peer group, participation in sports, roles taken in playing house, and stated wish to be a boy. Their parents do not differ on age, marital status, religion, or number of children. These descriptions provide the baseline for a forthcoming series of papers describing the development of these divergent patterns of sex-typed behaviors and the association of these early patterns with later psychosexual and psychosocial attributes.

Adult↗
PubMed1982

Bioavailability of iron- and copper-supplemented milk for Mexican school children.

Fortification of dairy products with trace metals requires use of assimilable compounds that do not catalyze off-flavors due to lipid peroxidation but show good biological availability. The Fe(III) and Cu(II) chelates of the promising chelator, lactobionic acid, have been compared to Fe(II) and Cu(II) salts for their ability to improve hematological status in a mildly anemic population. Fe- and Cu-fortified cow milk was administered to children (aged 6 to 15) in the Durango, Mexico, "school lunch" program. Children drank milk providing 20 mg Fe and 3 mg Cu as ferric/cupric lactobionate ("chelate") or ferrous/cupric chloride ("salt") for 5 of 7 days/wk for 3 months. Supplementation with "salt" and "chelate" raised Hb significantly by 1 and 0.3 g/dl, respectively, above the control (unsupplemented) group. No significant change was observed in incremental serum ferritin, serum Fe, or transferrin saturation, or in final serum Cu. Ferric lactobionate shows poorer bioavailability than ferrous ion in the presence of Cu, but milk can be an excellent vehicle for Fe or Cu supplementation.

Adolescent↗
PubMed1982

Micropuncture study of changes in glomerular filtration and ion and water handling by the rat kidney during pregnancy.

1. In rats receiving 200 mul. min(-1) sodium chloride, glomerular filtration rate, single nephron glomerular filtration rate, and fractional reabsorption were measured at various points along the nephron, and ionic concentrations measured in early distal tubular fluid in virgin and 6, 12 and 19 day pregnant rats.2. Glomerular filtration increased progressively until the twelfth day of pregnancy. At 19 days of pregnancy the glomerular filtration rate, while still above virgin levels, was reduced below 12 day pregnant levels.3. Single nephron glomerular filtration rates measured in proximal and distal tubules were different at both 12 and 19 days of pregnancy, indicating an alteration of tubuloglomerular feed-back.4. A change in the ratio of glomerular filtration rate: distal single nephron filtration rate indicated a redistribution of glomerular filtrate to juxtamedullary nephrons by the sixth day of pregnancy.5. Fluid reabsorption is similar up to the early distal tubule but it is not possible to say whether reabsorption is the same in proximal tubules. More fluid is reabsorbed by late distal tubules and collecting ducts in 12 and 19 day pregnant animals than in the virgin and 6 day pregnant animals.6. Changes in ion reabsorption by the loop of Henle occurred during pregnancy; sodium reabsorption was increased by the sixth day of pregnancy and potassium reabsorption by the twelfth day.

Animals↗
PubMed1982

Androgens and sexual behavior.

Sexual behavior in humans may be classified according to gender role, gender identity, and gender orientation. Sexually dimorphic behavior in humans is generally felt to be determined by postnatal socialization. Recent work in laboratory animals shows that sexual behavior is a function of circulating steroid hormones, particularly androgens. Testosterone given during a critical period in prenatal or immediate postnatal life causes permanent organizational effects on brain structure and function in laboratory animals. Studies in human patients with testicular feminization, 5-alpha-reductase deficiency, congenital adrenal hyperplasia, or prenatal steroid hormone exposure, provide clinical examples of possible effects of prenatal hormone action in the brain as opposed to postnatal socialization. However, these studies do not permit a clear assessment of the role played by either prenatal steroid hormones or postnatal socialization factors in the ultimate expression of sexual behavior in humans.

Androgens↗
PubMed1982

Absorption of biliary cobalamin in baboons following total gastrectomy.

Absorption of radiolabeled cobalamin in baboons was assessed by whole body counting. Retention of biliary cobalamin and an aqueous solution of cyanocobalamin was measured in normal baboons and in baboons after total gastrectomy by using 57Co-labeled biliary cobalamin and 58C0-cyanocobalamin, with and without baboon gastric juice containing intrinsic factor. Radiolabeled biliary cobalamin was obtained by intravenous injection of 57Co-cyanocobalamin in baboons and collection of bile through a cannula placed in the common bile duct. Cobalamin absorption was not completely abolished by gastrectomy and biliary cobalamin was better retained than cyanocobalamin; intrinsic factor enhanced absorption of both forms. After gastrectomy there was steady depletion of liver and serum cobalamin levels, which ceased after a new equilibrium was reached between a progressively diminishing cobalamin loss and the impaired but significant residual level of absorption. These studies in the nonhuman primate provide further information concerning the enterohepatic circulation of cobalamin and suggest that the form of cobalamin in bile may be more readily absorbed than is cyanocobalamin or that bile itself may have an enhancing effect on cobalamin absorption. The data also suggest that physiologically significant amounts of cobalamin may be absorbed in the absence of a gastric source of intrinsic factor.

Absorption↗