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Biomedical subjects

R M White

Publications and source records attributed to R M White.

At least 73 records · Page 4Linked to original sources
PubMed1982

Developmental pattern of a serum binding protein for multiplication stimulating activity in the rat.

The concentration of multiplication stimulating activity (MSA), an insulinlike growth factor (IGF), is high in fetal rat serum. We now report that MSA is exclusively associated wth an albumin-size binding protein in fetal rat serum; the growth hormone-dependent, gamma globulin-size binding protein, which predominates in the older animal, is absent from fetal rat serum. When (125)I-MSA was incubated with fetal rat serum and then gel filtered on Sephadex G-200, specific radioactivity eluted in the void volume (peak I) and the albumin region (peak III); by contrast, specific radioactivity eluted mainly in the gamma globulin region (peak II) in adult rat serum. Pools of the Sephadex G-200 fractions were chromatographed on Sephadex G-50, in 1 M acetic acid, to separate the binding protein from IGF activity. Analysis of IGF activity by chick embryo fibroblast bioassay, competitive protein binding assay, and MSA by radioimmunoassay revealed that all the IGF activity and MSA in fetal rat serum resided in peak III. Measurement of MSA binding capacity of the stripped binding protein by Scatchard analysis demonstrated that the majority of binding capacity also was found in peak III in fetal rat serum; most of MSA binding capacity was in peak II in adult rat serum. In fetal rat sera, in addition to the peak III binding protein, which is the major carrier of endogenous MSA, there is a component in peak I capable of specifically binding (125)I-MSA. This component elutes as a single species from a Sepharose-6B column. As MSA associated with peak III gradually declined in early neonatal life, peak II-associated IGF activity measured by chick embryo fibroblast bioassay showed a rise of activity with a peak at 5 d of neonatal life, a nadir at 20 d, with an increase again to attain adult levels. These studies demonstrate that the MSA binding protein in the fetus is different from the growth hormone-dependent binding protein in adult life.

Aging↗
PubMed1981

Multiplication stimulating activity (MSA) from the BRL 3A rat liver cell line: relation to human somatomedins and insulin.

The properties of multiplication stimulating activity (MSA), an insulin-like growth factor (somatomedin) purified from culture medium conditioned by the BRL 3A rat liver cell line are summarized. The relationship of MSA to somatomedins purified from human and rat plasma are considered. MSA appears to be the predominant somatomedin in fetal rat serum, but a minor component of adult rat somatomedin. In vitro biological effects of MSA and insulin in adipocytes, fibroblasts and chondrocytes are examined to determine whether they are mediated by insulin receptors or insulin-like growth factor receptors. The possible relationship of a primary defect of insulin receptors observed in fibroblasts from a patient with the rare genetic disorder, leprechaunism, to intrauterine growth retardation is discussed.

Adipose Tissue↗
PubMed1980

X-linked hypogammaglobulinemia and isolated growth hormone deficiency.

We undertook clinical, immunologic, and endocrinologic studies of a family in which two brothers and their two maternal uncles had a similar disorder characterized by hypogammaglobulinemia and isolated growth hormone deficiency. Recurrent sinopulmonary infections were a prominent feature in two patients. All patients had short stature and retarded bone age during childhood, and the adults had delayed onset of puberty. The immunodeficiency was characterized by absent specific antibody production in vivo and impaired immunoglobulin production in vitro. Three of the four patients lacked circulating B lymphocytes, even though tonsils were present in those patients. All patients had deficient growth hormone responses to insulin and arginine or levodopa. These patients have an X-linked recessive disorder, but their immunodeficiency differs from the X-linked immune disorders in the World Health Organization classification; their X-linked pattern of growth hormone deficiency, without other endocrine abnormality, is also unique.

Adolescent↗
PubMed1980

Increased levels of multiplication-stimulating activity, an insulin-like growth factor, in fetal rat serum.

Multiplication-stimulating activity (MSA), purified from medium conditioned by the BRL-3A rat liver cell line, previously has been shown to be closely related to the human somatomedins or insulin-like growth factors. A radioimmunoassay was utilized to measure MSA levels in sera from fetal, maternal, and young rats. A serum somatomedin-binding protein was found to interfere in the radioimmunoassay by competing with antibody for binding 125I-labeled MSA. Therefore, prior to radioimmunoassay, sera were filtered on Sephadex G-75 in 1 M acetic acid to dissociate and separate somatomedin activity from the binding protein. Concentrations of MSA by radioimmunoassay were 20- to 100-fold higher in feta rat sera (1.8-4.4 micrograms/ml) than in maternal sera. MSA levels gradually decreased after birth, reaching maternal levels by day 25 of extrauterine life. MSA concentrations in feta rat sera also were found to be correspondingly high by a rat liver membrane radioreceptor assay and a competitive binding protein assay using rat serum somatomedin-binding protein. The findings of higher levels of MSA in fetal than in maternal rat sera and the gradual decline in MSA serum concentrations after birth are in direct contrast to total somatomedin activities measured by biosassay. Thus, MSA may function as a growth factor in the fetal rat whereas other somatomedins may play a role in stimulating growth during extrauterine life.

Age Factors↗
PubMed1979

Age bias, referral for psychological assistance and the private physician.

The responses of 60 physicians to a questionnaire comprised of a brief section for demographic information and eight vignettes describing patients with obvious psychiatric symptoms were analyzed. On alternate forms of the questionnaire, the age of the patient was reversed for each vignette. Old patients were referred for psychological assistance significantly less frequently (p less than .001) than were young patients, although both groups were described as presenting identical symptomatology. For those vignettes that described more severe behavioral disturbances, differences in the referral rates of young and not old patients was most pronounced. The results are discussed in terms of age bias on the part of the referring physician and the effect this may have on the provision of mental health treatment for elderly persons.

Adult↗
PubMed1979

Further characterization of growth hormone-dependent somatomedin-binding proteins in rat serum and demonstration of somatomedin-binding proteins produced by rat liver cells in culture.

The somatomedin-like peptide multiplication-stimulating activity (MSA) binds specifically to rat serum. The pattern of MSA binding is GH dependent. Specific binding of [125I]iodo-MSA in normal rat serum is primarily in the gamma-globulin region (peak II) on Sephadex G-200, while MSA binding in hypophysectomized (hypox) rat serum is near the albumin region (peak III). This study further characterizes the peak II and peak III somatomedin-binding proteins produced by rat liver cells in culture. [125I]Iodo-MSA binding to normal rat serum is abolished by trypsin pretreatment of rat serum, suggesting that MSA binds to protein components of serum. The only detectable somatomedin activity (measured by [3H]thymidine incorporation into chick embryo fibroblast DNA) in fractions of normal rat serum chromatographed on Sephadex G-200 coincides with peak II binding of [125I]iodo-MSA. In hypox rat serum, the majority of detectable somatomedin activity is in the peak III region. There is complete displacement of the human somatomedins [125I]iodoinsulin-like growth factor I and II and [125I]iodosomatomedin A from the rat serum-binding sites by unlabeled MSA, suggesting that the human somatomedins bind to the same sites as MSA. Treatment of normal rat serum with 1 M acetic acid dissociates somatomedin activity from its binding proteins and converts somatomedin-binding proteins from peak II to peak III. Scatchard analysis of competitive binding data using [125I]iodo-MSA yields a binding affinity that is not appreciably different for either normal or hypox rat sera. The binding capacity of normal or acid-treated normal rat serum for MSA is significantly greater than that for comparably treated hypox rat sera. Although the site of synthesis of somatomedin-binding proteins in vivo is unknown, specific somatomedin-binding proteins are synthesized by two rat liver cell lines in culture. These rat liver cell somatomedin-binding proteins have the same molecular size and the same binding affinity for MSA as the peak III somatomedin-binding protein(s) in rat serum.

Animals↗
PubMed1977

Suppression of the temperature-sensitive phenotype of a mutant of reovirus type 3.

A revertant of a reovirus group A temperature-sensitive mutant was crossed with wild type. More than 50 percent of the progeny were temperature sensitive. In all of the temperature-sensitive progeny examined by recombination tests, the temperature-sensitive lesion was in group A. The results indicate that the revertant was phenotypically suppressed.

Mammalian orthoreovirus 3↗
PubMed1977

Enzyme-coupled measurement of uric acid in serum with a centrifugal analyzer.

An early-reading blank-corrected end-point determination of uric acid in serum has been developed for use with a centrifugal analyzer. The method is based on a modification of the uricase (urate:oxygen oxidoreductase, EC 1.7.3.3)/catalase (hydrogen peroxide:hydrogen peroxide oxidoreductase EC 1.11.1.6)/aldehyde dehydrogenase (aldehyde:NAD(P)+ oxidoreductase, EC 1.2.1.5)-coupled analytical scheme reported by Haeckel [Z. Klin. Chem. Klin. Biochem. 14, 101 (1976)]. Sensitivity and precision of the method are excellent, and results compare well with those obtained by the Kageyama procedure [Clin. Chim. Acta 31, 421 (1971)].

Aldehyde Oxidoreductases↗