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Biomedical subjects

P Roos

Publications and source records attributed to P Roos.

At least 91 records · Page 5Linked to original sources
PubMed1980

Human pituitary thyrotropin. Isolation and recombination of subunit isoforms.

The alpha and beta subunits of human pituitary thyrotropin were prepared by a process developed earlier. Each subunit preparation contained four isoforms which were isolated by preparative agarose-suspension electrophoresis. The alpha subunit isoforms were homogeneous upon examination by analytical electrophoresis in polyacrylamide gel. Contrarily, the isolated beta subunit isoforms were always to some extent contaminated by the adjacent more acidic component. This was considered to show a transformation of these forms favoured by hydroxyl ions. Amino acid analysis revealed no differences between the alpha isoforms nor between the beta isoforms, and the amino acid compositions were in very good agreement with those earlier obtained for multi-alpha and multi-beta preparations. Attempts to recombine different alpha and beta isoforms were made at pH 7.0. The activities of recombined thyrotropin (in terms of MRC Research Standard A) ranged from 1.1 unit/mg (recombination of two minor components) to 3.5 units/mg (recombination of two major components). The activities of native and recombined thyrotropins as well as the subunit activities were followed by radioimmunoassays. The activity of native thyrotropin as a function of time was studied under different storage conditions. The subunit activities were also measured. All conditions resulted in a decrease in the thytrotropin activity (about 40% in 10 weeks). This decrease was not due to dissociation as the subunit activities remained approximately constant.

Amino Acids↗
PubMed1980

On the mechanism of elevated prostaglandin E2 production in 3T3 fibroblasts transformed by polyoma virus.

Polyoma-virus-transformed 3T3 fibroblasts (py 3T3 cells) produce considerably more prostaglandin E2 than regular 3T3 cells during growth in cell culture. Incubations with exogenous arachidonic acid showed no increase in prostaglandin-producing capacity in the transformed cells. The rates of degradation of prostaglandin E2 were similar in the two lines. After labeling of cells with [1-14C]arachidonic acid, py 3T3 cultures continuously released radioactivity while the release by regular 3T3 cells was almost completed after 3 h. Prostaglandin E2 production during short incubations in buffer at various times after medium change was constantly higher in the transformed cells. Furthermore, hydrocortisone completely inhibited prostaglandin synthesis by the transformed cells. These results suggest that the increased formation of prostaglandin by py 3T3 cells is due to continuously elevated activity of phospholipase A2 or another acyl hydrolase.

Animals↗
PubMed1979

Isolation of human pituitary prolactin.

A process developed earlier for the extraction of human follitropin, lutropin, thyrotropin and growth hormone from homogenized frozen pituitaries provided a residue utilized for the isolation of prolactin. The isolation procedure involved extraction at pH 9.8, molecular sieve chromatography on Sepharose CL-6B, hydrophobic interaction chromatography on phenyl-Sepharose CL-4B, molecular sieve chromatography on Sephadex G-100 Superfine, and ion-exchange chromatography on DEAE-Sepharose CL-6B using a convex gradient. The progressive purification was guided by radioimmunoassays. The final product was obtained in yields of 31 microgram/gland, and was equipotent with a pituitary preparation (VLS-3) supplied by the National Pituitary Agency (NIH, Bethesda, U.S.A.). Contamination hormones negligible (less than 0.05%). No heterogeneity of the isolated prolactin was observed by sedimentation-equilibrium analysis in the ultracentrifuge, by SDS electrophoresis in polyacrylamide gel or by molecular sieve chromatography in 6 M guanidine hydrochloride. These different techniques gave values in the range of 21 000-23 000 for the molecular weight of prolactin. In free zone electrophoresis, and also in polyacrylamide gel electrophoresis the prolactin preparation was, however, heterogeneous and resolved at alkaline pH into three distinct components. The former technique permitted isolation and assay of the components, indicating that they were all fully active.

Chromatography, Agarose↗
PubMed1978

Human pituitary thyrotropin. Isolation of alpha and beta subunits by hydrophobic interaction chromatography.

Various conditions for the dissociation of highly purified human pituitary thyrotropin into subunits have been investigated. Dissociation on a preparative scale was accomplished by treatment with 1 M propionic acid at 32 degrees C for 16 h. The isolation of one alpha and two beta subunits was achieved by hydrophobic interaction chromatography on pentyl-Sepharose-4B. Radioimmunological technique was utilized to classify the subunits in accordance with current nomenclature and also to express their activities. The activities of the subunits overlapped insignificantly (less than or equal to 0.3%) and their content of intact thyrotropin was negligible (less than 0.05%). The characterization of the subunits included determination of their amino acid compositions. Analytical polyacrylamide gel electrophoresis of the subunits at acid and alkaline pH values revealed heterogeneity. By free-zone electrophoresis at alkaline pH it was possible to isolate four discrete iso-forms of both the alpha and the beta subunit. All these eight individual subunits had activities consistent with those of their immediate precursor fractions. Isolation of electrophoretically homogeneous thyrotropin subunits has not been reported previously.

Amino Acids↗
PubMed1977

Human pituitary thyrotropin. Characterization of five glycoproteins with thyrotropin activity.

Human pituitary thyrotropin prepared by chromatography on hydroxyapatite or on SP-Sephadex was fractionated into five active components by preparative poly-acrylamide gel electrophoresis. The potency of the five components was 4-9 units human Research Standard A/mg. Examination of the components by analytical electrophoresis and by immunological methods revealed no heterogeneity. Ultracentrifugaiton of the three major components showed homogeneity with sedimentaiton coefficinets in the range of 2.4-3.0 S and a value for the molecular weight of about 33 000. Amino acid and carbohydrate analyses indicated close similarites between the five components.

Amino Acids↗
PubMed1975

Human pituitary luteinizing hormone. Isolation and characterization of four glycoproteins with luteinizing activity.

Two major and two minor components of human luteinizing hormone (lutropin) were isolated from whole frozen pituitaries by a procedure involving extraction of homogenized pituitaries, (NH4)2SO4 fractionation, chromatography on DEAE-cellulose, Sephadex G-100, and SE-Sephadex C-50 and electrophoresis in polyacrylamide gel. The isolation procedure was monitored by both bioassays and radioimmunoassays. Contamination of the final products by other pituitary hormone activities was very low. The four lutropin components were all homogeneous by polyacrylamide gel electrophoresis (a sieving medium) and by free zone electrophoresis (a non-sieving medium). No heterogeneity was observed when the components were studied in the ultracentrifuge by sedimentation-equilibrium technique. The molecular weights of the components were in the range of 34 000-40 000. Sedimentation velocity experiments with the two major components revealed in each case one boundary with S20,W values of 3.2 S and 3.5 S. Further evidence for the homogeneity of the components was the observation of only one precipitin line for each component upon immunodiffusion against a rabbit anti-human lutropin serum. Amino acid and carbohydrate analyses indicated close similarity among the four components. From the analysis data the molecular weights of the components were calculated to be 31 000-33 000.

Amino Acids↗
PubMed1975

Isolation of five active thyrotropin components from human pituitary gland.

A procedure is described for the isolation of human pituitary thyroid-stimulating hormone (thyrotropin). The starting material was a side-fraction provided by the earlier developed process for the purification of growth hormone from whole frozen pituitaries. This fraction was further purified by successive chromatography on Bio-Gel P-150, Bio-Gel HT hydroxyapatite, and SP-Sephadex C-50. The resulting preparation was obtained in yields of 10 mg/kg of pituitary tissue and had a thyrotropin potency of 11 units human Research Standard A/mg as measured by a specific radioimmunoassay. Contamination by other pituitary hormone activities was low. In the ultracentrifuge a single sedimenting boundary was registered with an s20,w value of 2.7 S. The molecular weight as determined by sedimentation-equilibrium experiments was 34 000 in phosphate buffer, pH 7.0, and 17 700 in 1 M propionic acid. This thyrotropin preparation was, however, electrophoretically heterogenous. Following preparative polyacrylamide gel electrophoresis five different components associated with thyrotropin activity were isolated. Isolation on a preparative scale of electrophoretically homogeneous human thyrotropin has not earlier been reported. One of the thyrotropin components was characterized with respect to molecular weight and amino acid composition. The data were consistent with a molecular weight of 33 000 from sedimentation-equilibrium analysis at pH 7 and with 268 amino acid residues per molecule.

Amino Acids↗
PubMed1975

Experimental evaluation of sensorimotor patterning used with mentally retarded children.

In the present study, a sensorimotor "patterning" program used with 66 institutionalized, mentally retarded children and adolescents was evaluated. The subjects were randomly assigned to one of three groups: (a) Experimental 1 group, which received a program of mobility exercises including patterning, creeping, and crawling; visual-motor training; and sensory stimulation exercises; (b) Experimental 2 group, which received a program of physical activity, personal attention, and the same sensory stimulation program given to the first group; or (c) Passive Control group, which provided baseline measures but which received no additional programming as part of the study. Experimental 1 group subjects improved more than subjects in the other groups in visual perception, program-related measures of mobility, and language ability. Intellectual functioning did not appear to be enhanced by the procedures, at least during the active phase of the project. The results were discussed with reference to other researchers who have failed to support the patterning approach, and some reasons were suggested for the differences between the present and past investigations.

Adolescent↗
PubMed1975

Evaluation of cold areas on the thyroid scan with 67Ga-citrate.

Cold areas on 131I or 99mTc thyroid scans were re-evaluated using 67Ga-citrate in 134 patients. In 62 patients surgical specimens were obtained for histologic studies. Of 46 benign lesions, all had negative 67Ga scans, and 67Ga scans in 5 of the 16 lesions judged to be malignant were positive. It was thought that the sensitivity of the method did not warrant its use for routine screening in evaluations of malignancy of thyroid nodules.

Gallium Radioisotopes↗