Search PubMed⌕ Search

Biomedical subjects

S C Miller

Publications and source records attributed to S C Miller.

At least 217 records · Page 12Linked to original sources
PubMed1984

Identification of 17 beta-estradiol as the estrogenic substance in Saccharomyces cerevisiae.

Saccharomyces cerevisiae possesses a high-affinity estrogen binding protein and an endogenous ligand that displaces [3H]estradiol from both the yeast binding protein and mammalian estrogen receptors. Semipurified preparations of this ligand have been shown to exhibit estrogenic activity in mammalian systems. We now describe the purification procedure and ultimate identification of the estrogenic substance in extracts of S. cerevisiae as 17 beta-estradiol. Organic solvent extracts of commercially obtained dried yeast were sequentially chromatographed on silica gel columns and then subjected to a series of reversed phase HPLC fractionations. Active ligand was monitored by [3H]estradiol displacement in a rat uterine cytosol assay. After seven chromatography steps, the purified and highly active ligand exhibited a single peak with retention times identical to those of 17 beta-estradiol on both HPLC and GC. The yeast material was identified as 17 beta-estradiol by its UV absorbance and mass spectrometric fragmentation pattern. In addition, radioimmunoassay confirmed the presence of approximately the same mass of 17 beta-estradiol (approximately equal to 800 ng/1.5 kg of yeast) as estimated both by a competitive binding assay with estrogen receptor and by mass spectrometry. Extraneous contamination by estradiol was excluded by repeat experiments with different batches of starting material and demonstration of estradiol by RIA in conditioned medium and cell pellets of laboratory-grown S. cerevisiae whereas non-conditioned medium did not possess the steroid. We conclude that 17 beta-estradiol is a yeast product.

Estradiol↗
PubMed1984

The relationship of bone marrow type and microvasculature to the microdistribution and local dosimetry of plutonium in the adult skeleton.

Most plutonium-induced bone tumors in beagles arise in trabecular bone sites surrounded by hematopoietic tissue. The microvasculature and the relative incorporation of 241Pu (a low energy beta emitter) on trabecular bone surfaces from red and fatty marrow sites were studied in the adult beagle. The vascular volume, as determined by India ink perfusion, was about 16% in the red marrow and about 2% in the fatty marrow. The red marrow has large vascular sinusoids with a discontinuous endothelial lining whereas fatty marrow has a closed capillary bed. Plutonium concentrations on bone surfaces of red marrow sites are about 0.43 pCi/cm2/nCi/kg of injected dosage, a factor of eight greater than at fatty marrow sites (0.053 pCi/cm2/nCi/kg). The differences in the bone marrow microvasculature between red and fatty marrow help to explain differences in plutonium incorporation and local bone physiology in these skeletal sites. These observations may relate to the nonuniform distribution of plutonium-induced osteosarcomas observed in adult, long-lived mammals.

Animals↗
PubMed1984

Meeting the eye care needs of video display terminal operators.

The introduction of video display terminals into the workplace has brought about increased visual complaints and concern for worker's health and safety. Optometrists have a significant opportunity to provide a valuable service in this expanding area of occupational/environmental vision. This article discusses the visual, ergonomic and environmental factors which optometrists must be familiar with in order to meet the eye care needs of video display terminal operators.

Data Display↗
PubMed1984

Regulation of cholesterol biosynthesis and esterification by 25-hydroxycholesterol in a macrophage-like cell line: uncoupling by progesterone.

The coordinated control of cholesterol biosynthesis and esterification by 25-hydroxycholesterol was studied in the macrophage-like cell line P388D1. Since 25-hydroxycholesterol rapidly stimulated incorporation of [3H]oleate into the cholesteryl ester fraction of these cells, we have tested the possibility that the well-known inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) by 25-hydroxycholesterol might be the indirect consequence of an increased cholesterol esterification rather than a direct effect on HMG-CoA reductase. The experimental results show that progesterone, an inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT), when added together with 25-hydroxycholesterol, abolished the increased cholesterol esterification without affecting the inhibition of HMG-CoA reductase by 25-hydroxycholesterol. Thus, uncoupling cholesterol esterification had no effect on 25-hydroxycholesterol's ability to inhibit HMG-CoA reductase. Unexpectedly, pretreatment of P388D1 cells with 25-hydroxycholesterol resulted in no elevation of ACAT activity as measured in broken cell preparations. Therefore, the possibility that 25-hydroxycholesterol stimulated cholesteryl ester formation by increasing the amount of cholesterol available for esterification, rather than by acting directly on ACAT activity, was considered. Labeling experiments using [14C]-cholesterol have provided evidence for this assumption.

Acetates↗
PubMed1984

Radiation dose rates to the proximal humerus of growing beagles injected with 239Pu.

The anatomical distribution of 239Pu in the proximal humerus was studied in four beagles injected at 90 days of age and sacrificed 7, 28, 56, and 128 days after injection, respectively. Initial deposition in each humerus was 3.1% of the injected Pu; 41% of that was retained with a net halftime of 248 days; for the remaining 59% no decrease was observed with time. Sixty-one percent of the initial deposit was concentrated in the proximal epiphysis and metaphysis. Average radiation dose rates to trabecular bone of the epiphysis, to those parts of the metaphysis that were formed before and/or after injection, and to the area corresponding to the primary and secondary spongiosa were determined by fission track autoradiography. Local dose rates within the range of 10 microns of the endosteal surface, to the marrow and to osseous tissue were calculated. Because of the rapid growth and modeling rate, surface deposits declined rapidly. In the metaphysis, bone formed after injection contained less than 1/2 the Pu concentration of bone which was present at the time of injection. At 100 days of age, bone mineralization as determined by the ash weight/wet weight ratio, and the fraction of bone volume occupied by mineralized tissue was 1/2 that seen in young adult beagles. The surface/volume ratio was twice as high as in young adult beagles. The possible effects of local radiation doses were correlated with areal densities of cells and types of cells at risk. Comparisons were made with corresponding sites from the humerus of beagles injected as young adults.

Aging↗
PubMed1983

Studies on the possible chemical, immunochemical and morphological differences at the cell surfaces of immunosensitive and immunoresistant, Moloney virus-induced, lymphoma cell-lines.

Comparison was made of several cell-surface parameters in the immunosensitive, Moloney virus-induced, mouse lymphoma, YAC, and its immunoresistant variant, YACIR. The characteristics of the two cell lines appeared to be similar by most of the criteria employed. The poly(acrylamide)-gel electrophoresis (with sodium dodecyl sulfate) patterns, after staining with Coomassie Brilliant Blue, of detergent-solubilized materials, appeared to be identical. After elution from a gel filtration column, no major differences were observed in the protein profiles of material cleaved from viable cells by proteolysis. Scanning and transmission electron microscopy revealed no major differences between the YAC and YACIR cells. The concentration of the lectins, Ricinus communis agglutinin, concanavalin A, wheat-germ agglutinin, and Solanum tuberosum (potato) agglutinin, required to agglutinate viable cells of the two lines were not significantly different. Neither cell was agglutinated by the lectins from Dolichos biflorus or Vicia graminea. Significant differences were, however, observed in the concentrations of lectin from Arachis hypogaea (peanut) needed to agglutinate the two cells. Although similar amounts (184-188 micrograms/10(9) cells) of sialic acid were released from viable cells by neuraminidase (V. cholerae), striking differences were observed in the composition of this material: 48% of N-glycolylneuraminic acid for YAC and 15% for YACIR. The remainder was N-acetylneuraminic acid for each cell line.

Agglutination↗
PubMed1983

Structure, cytochemistry, endocytic activity, and immunoglobulin (Fc) receptors of rat testicular interstitial-tissue macrophages.

Macrophages are common in rat testicular interstitial tissues. Interstitial-tissue macrophages were characterized using ultrastructural, cytochemical, immunologic, and autoradiograhic methods. Testicular interstitial-tissue macrophages have a single indented nucleus, paranuclear Golgi complex, rough endoplasmic reticulum, coated vesicles, and numerous heterogeneous lysosomal vacuoles. Long filopodia and lamellopodia extent from the macrophage cell body into the lymphatic space. Macrophages are usually found adjacent to Leydig cells, and numerous Leydig cell processes are inserted into coated membrane invaginations on the macrophage surface. Secondary lysosomal vacuoles in the macrophage are cytochemically reactive for acid phosphatase (trimetaphosphatase) and aryl sulfatase. Testicular interstitial macrophages are endocytically active, avidly incorporating exogenously administered trypan blue dye and monomeric plutonium-citrate. Macrophages were isolated from the testes by allowing them to adhere to glass. The isolated macrophages were found to have receptors for the Fc portion of immunoglobulin G on their surface. The association of macrophages with Leydig cells and their endocytic and immunologic activity suggests that these cells may play an important role(s) in testicular functions. In addition, the ability of these cells to incorporate exogenous materials indicates that they could have a role in gonadal toxicity reactions.

Animals↗
PubMed1983

Altered sterol synthesis and its relationship to fluid-phase endocytosis in a macrophage cell line P388D1.

In a previous study glucocorticoids have been shown to depress the rate of fluid-phase endocytosis in a macrophage cell line, P388D1. This effect was observed when either fluorescein-labeled dextran or horseradish peroxidase (HRP) was used to measure endocytosis. In this report the relationship between cholesterol synthesis and endocytosis was examined in light of the ability of glucocorticoids to inhibit cholesterol biosynthesis. Two known inhibitors of cholesterol biosynthesis, ML-236B and 25-hydroxycholesterol (25-OH), were compared with dexamethasone (dex) for the ability to suppress endocytosis in cells grown in media supplemented with either 10% whole or delipidized neonatal bovine serum (NBS). In 10% whole serum all inhibitors reduced the uptake of HRP after 12 h incubation. Dexamethasone (1 microM) suppressed endocytosis by 30% whereas 25-OH (2.5 microM) and ML-236B (11.6 microM) inhibited by 38 and 52%, respectively. Supplementation of the growth medium with mevalonolactone (3.4 mM) prevented the inhibition of endocytosis by ML-236B. In contrast, mevalonolactone supplementation did not prevent either dex or 25-OH from suppressing endocytosis. The same pattern of results was obtained when cultures were grown in delipidized NBS. After 4 h all inhibitors caused a decrease in amount of [14C]acetate incorporated into both nonsaponifiable lipids and digitonin precipitable sterols. Although dex inhibited cholesterol biosynthesis, total cellular cholesterol was unaffected by dex treatment after 24 h incubation. It is suggested that in addition to suppressing mevalonate synthesis, 25-OH, and by analogy dex, may act at some metabolic site(s) distal to the formation of mevalonate.

Animals↗
PubMed1983

Genetically determined resistance to foreign bone marrow transplantation in mice: characterization of the effector cells.

Mice of most strains show a genetically determined ability to reject a variety of foreign marrow grafts even after lethal irradiation. The phenomenon is both host strain and donor marrow graft-dependent. To characterize the effector cell responsible for graft rejection, attempts were made to 1) determine to what morphologic subclass it belongs; 2) determine its life span; and 3) establish whether genetically different host environments influence the functioning of the effector cell. Mice of the 129/J strain (normally nonresistant), C57BL/6 strain (made non-resistant), and the homozygous mutants of C57BL/6, i.e., C57BL/6 (bg/bg), were recipients of C57BL/6 marrow or spleen cells. After lethal irradiation, hosts were given marrow or spleen cells from normal, strongly resistant C57BL/6 donors pretreated with a) 950 R whole body irradiation or b) twice daily injections for 4 days of the cell cycle toxic drug hydroxyurea followed by 950 R. In other cases, hosts were recipients of the lymphoid cell-rich fraction of marrow from irradiated C57BL/6 donors or adherent cells taken from cultures of marrow cells of unirradiated C57BL/6 donors. Three hours after receiving C57BL/6 marrow or spleen cells, irradiated hosts were given allogeneic DBA/2 marrow (always strongly rejected by C57BL/6 mice and always accepted by 129/J strain mice). Seven days later, host spleens were removed and the numbers of microscopic colonies were counted from subserial sections. The results demonstrate that 1) mice either normally or rendered nonresistant to a marrow allograft can be made to develop resistance by the administration of either whole spleen cells or marrow lymphoid cells from lethally irradiated strongly resistant donors; 2) adherent cells from cultures of marrow from strongly resistant mice are ineffective in conferring resistance; 3) the cell effective in conferring resistance has a life span greater than 4 but less than 7 days; and 4) the effector cell can function in genetically different environments of nonresistant strains.

Animals↗
PubMed1983

Recommended vision standards for police officers.

A recommended vision standard for police officers is presented. The visual capabilities needed to perform various police duties are described. A specific vision standard, along with criteria for screening referral or screening failure are given for each category of visual skills required for police work.

Color Vision Defects↗
PubMed1983

Professional marketing for optometry.

Most optometrists are unfamiliar with the concepts of marketing. Yet to be successful in today's highly competitive health care environment, some marketing efforts may be needed. The four key elements of successful marketing are reviewed and related to professional optometric practice applications. Understanding what the public wants and needs in vision care is a key to developing an effective professional marketing program. Various strategies for retaining and attracting patients are discussed.

Fees and Charges↗
PubMed1983

Tissue, cellular, and subcellular distribution of 241Pu in the rat testis.

The distribution and localization of 241Pu in rat testes were determined by quantitative autoradiography. Rats were given an intravenous injection of 241Pu citrate and tissues were collected 1 week later. The tissue distribution of 241Pu was determined by light microscope autoradiography. Significant concentrations of 241Pu were observed in the interstitial tissue but not in seminiferous tubules. The cellular distribution and subcellular localization of 241Pu were determined by electron microscope autoradiography. Within the interstitial tissue, 241Pu was concentrated in macrophages. There was no preferential localization of 241Pu in any other interstitial tissue components. Within interstitial tissue macrophages, 241Pu was concentrated in the lysosomal system of the cell. Other organellar compartments of the cell did not preferentially incorporate 241Pu. The association of 241Pu with the macrophage lysosomal system may explain the long retention times of Pu in testes as observed in experimental studies.

Animals↗
PubMed1983

Physicochemical and morphological characterization of a new allotransplantable mammary carcinoma ascites subline, TA3-St/ticol/-A.

The TA3-St/ticol ascites cell (I), immunoselected from the strain-specific TA3-St mammary carcinoma ascites cell of the strain A mouse for decreased H-2a antibody-binding capacity, underwent a spontaneous transition in vivo to a new cell line, TA3-St/ticol/-A (II). Line II was more allotransplantable than was the parental line (line I), and its absorptive capacity for anti-H-2a antibody was manyfold less than line I. Disruption of line II cells by lyophilization did not increase the absorptive capacity, in contrast to its marked enhancement in the TA3-Ha ascites cell under similar conditions. An explanation for the enhanced allotransplantability of line II may be related to either a loss of H-2a antigens or altered macromolecular structures at the cell surface: sialic acid, consisting of 93% N-glycolylneuraminic acid for line II and 9% for line I; altered chemical structures of cell surface glycoproteins, particularly a high-molecular-weight glycoprotein present in much greater proportion in line II than in line I; a macromolecular complex released by a protease from line I, but not line II; and I being agglutinable by concanavalin A, but not line II. Electron microscopy showed line II to be more pleomorphic and less rounded than was line I. Under high-resolution electron microscopy, the cell surfaces of both allotransplantable cells, lines II and I, exhibited thin filamentous material, material not observed at the surface of the nonallotransplantable TA3-St ascites cell.

Animals↗
PubMed1983

Cell surface characteristics of an allotransplantable TA3 ascites subline resulting from a process of immunoselection.

Comparison of the cell surface characteristics of the parental strain-specific TA3-St ascites cell (I) of the strain A mouse and the more allotransplantable TA3-St/ticol ascites cell (II), immunoselected for reduced absorption of anti-H-2a antibody from Cell I, revealed the following. Cell II, like Cell I, possessed no detectable epiglycanin at its surface, as neither cell absorbed more than 0.5% as much of the antiepiglycanin antibody as was absorbed by the epiglycanin-containing allotransplantable TA3-Ha ascites cell. Tritium-labeled glycoproteins, with polyacrylamide slab gel electrophoresis with sodium dodecyl sulfate and with isoelectric focusing of detergent-treated cells, exhibited marked quantitative differences, but qualitative differences were not established. Glycopeptides cleaved from each cell by proteolysis and fractionated by gel filtration gave similar elution profiles, and the column fractions possessed similar carbohydrate and amino acid compositions. Less sialic acid (170 micrograms/10(9) cells) was removed by neuraminidase from Cell II than from Cell I (270 micrograms/10(9) cells), and the compositions (9% N-glycolylneuraminic acid for Cell II and 20% for Cell I) were different. Transmission and scanning electron microscopy showed rough irregular folds and ridges on the surfaces of each cell, but Cell II appeared more pleomorphic and less rounded than did Cell I. High-resolution transmission electron microscopy showed filamentous material at the surface of Cell II, but not at the surface of Cell I.

Amino Acids↗