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Biomedical subjects

H Green

Publications and source records attributed to H Green.

At least 127 records · Page 7Linked to original sources
PubMed1985

A dual effector theory of growth-hormone action.

Growth hormone increases tissue formation by acting both directly and indirectly on target cells. The direct action promotes the differentiation of precursor cells; this has been demonstrated for two mesenchymal cell types. Insulin-like growth factor I (IGF-I) is not able to substitute for growth hormone in promoting this differentiation, but it is proposed that its mitogenic action selectively promotes cell multiplication in young differentiated clones. As tissue growth results from both the creation of new differentiated cells and their subsequent clonal expansion, both effectors increase tissue growth, but by different means.

Adipose Tissue↗
PubMed1985

Specificity of gene expression in adipocytes.

During the differentiation of preadipose 3T3 cells into adipose cells, the mRNAs for three proteins increase strikingly in abundance. To determine the degree of cell-type specificity in the expression of these mRNAs, we estimated their abundances in several nonadipose tissues of the mouse. None of these mRNAs was strictly confined to adipocytes, but the ensemble of three mRNAs was rather specific to adipocytes. Insofar as is revealed by these three markers, the distinctive phenotype of adipocytes is the result of the enhanced expression of a number of genes, none of which is completely silent in all other cell types.

Adipose Tissue↗
PubMed1984

Eye movements during sleep in weightlessness.

The number of eye movements during sleep increased during the first sleep period in zero gravity but returned to normal by the second night. These rapid-eye-movement functions in flight may be the first variations of an oscillatory system. The ratio of the higher and lower eye movement frequencies oscillates within normal-gravity limits.

Eye Movements↗
PubMed1984

Gunshot injuries seen at Johannesburg Hospital during 1982.

Gunshot injuries seen at Johannesburg Hospital during 1982 are reviewed. The incidence of these injuries has been increasing over the last few years, and they now cause a significant problem in terms of workload and number of beds occupied. The use of a rifle or handgun is becoming more common, not only for suicidal purposes but also as a weapon of assault.

Admitting Department, Hospital↗
PubMed1984

Bioassay of retinoids using cultured human conjunctival keratinocytes.

The biological action of retinoids has been assayed using the differentiated properties of cultured human conjunctival keratinocytes. The effects measured were the suppression of envelope cross-linking and the promotion of synthesis of a keratin of molecular weight 40,000. Among the retinoids tested, the most powerful was the arotinoid Ro 13-6298, which reduced envelope formation detectably at 10(-11) M and by 90% at a concentration of 2 X 10(-10) M. The arotinoid was about 15 times more potent than trans-retinoic acid. The order of effectiveness of the retinoids in suppressing envelope cross-linking was the same as the order of effectiveness in promoting the synthesis of the 40-kd keratin.

Biological Assay↗
PubMed1984

Participation of membrane-associated proteins in the formation of the cross-linked envelope of the keratinocyte.

Cultured keratinocytes, like those in natural squamous epithelia, form submembranous protein envelopes cross-linked by cellular transglutaminase. During the cross-linking, the cytosolic protein involucrin becomes incorporated into the envelope and can no longer be extracted by detergents. We show here that when transglutaminase is activated in cultured keratinocytes, at least six other proteins also become nonextractable. In contrast to involucrin, these proteins are associated with membranes. Two of the proteins (210 and 195 kd) are differentiated products specific to the keratinocyte; like involucrin, they are absent from small keratinocytes and fibroblasts, but appear in larger keratinocytes during the course of their terminal differentiation. The other proteins that become nonextractable cannot be destined exclusively for envelope formation since they are also present in fibroblasts. Transglutaminase is used by the mature (large) keratinocyte to make a detergent-resistant envelope from what appears to be a mixture of differentiation-specific and nonspecific proteins, both membrane-bound and cytosolic.

Acyltransferases↗
PubMed1984

Growth hormone promotes the differentiation of myoblasts and preadipocytes generated by azacytidine treatment of 10T1/2 cells.

Previous studies have shown that growth hormone promotes the differentiation of preadipose 3T3 cells into adipose cells. This action of the hormone is not mediated by insulin-like growth factor 1 (IGF-1), but is exerted directly on the preadipocytes. In order to determine whether growth hormone promotes the differentiation of other mesenchymal cell types, we have examined its effect on the formation of multinucleated muscle cells from myoblasts. Clone mu cells, generated from line 10T1/2 by treatment with azacytidine, were known to be capable of undergoing myogenesis. When these cells were cultivated in a medium not able alone to support their differentiation, the addition of physiological concentrations of growth hormone strongly promoted myogenesis. When fetal calf serum was used instead of growth hormone to promote myogenesis, the effectiveness of the serum was reduced by the addition of a specific antiserum to growth hormone. IGF-1 could not substitute for growth hormone in promoting myogenesis. When another 10T1/2 line not ordinarily able to form myotubes was subjected to treatment with 5-azacytidine, it was subsequently able to give rise to muscle and adipose cell colonies; the number of such colonies was much increased by the presence of growth hormone. We have not been able to demonstrate a similar dependence on growth hormone for myogenesis by the established lines L6E9 and C2.

Adipose Tissue↗
PubMed1984

Cloning of cDNAs specifying vitamin A-responsive human keratins.

In human cultured epidermal and conjunctival keratinocytes, vitamin A promotes the synthesis of keratins 13 and 19 of the catalog of Moll et al. [Moll, R., Franke, W.W., Schiller, D.L., Geiger, B. & Krepler, R. (1982) Cell 31, 11-24] but does not alter the synthesis of keratins 5 and 6. To study this effect of the vitamin, cDNAs specifying each of these keratins were cloned in pBR322. Characterization of the clones by hybrid selection of mRNA and by hybridization of size-fractionated mRNA indicated that each was specific for a single mRNA. Treatment of epidermal cells with arotinoid Ro 13-6298, a potent synthetic analog of retinoic acid, increased the abundance of mRNA for keratin 13 by 25-fold and for keratin 19 by greater than 40-fold but had no effect on the abundance of mRNA for keratins 5 and 6.

Benzoates↗
PubMed1984

Contribution of growth hormone to the adipogenic activity of serum.

GH promotes the conversion of cultured preadipose 3T3 cells into adipose cells. The serum of most animals also promotes this differentiation. In order to determine the extent to which GH is responsible for the adipogenic activity of serum, we used a specific antiserum able to suppress completely the adipogenic activity of rat and bovine GH. This antiserum also suppressed all the adipogenic activity secreted into culture medium by a rat pituitary cell line as well as all the adipogenic activity of crude bovine pituitary extract. When tested against the adipogenic activity of serum, the antiserum to GH reduced the activity by one third to half. It is concluded that 1) GH in the concentration and form present in serum is an effective promoter of adipose differentiation, and 2) there exists in serum another adipogenic activity not immunochemically recognizable as GH. This activity is presumed to be of nonpituitary origin.

Adipose Tissue↗
PubMed1983

Molecular cloning of mRNA from 3T3 adipocytes. Regulation of mRNA content for glycerophosphate dehydrogenase and other differentiation-dependent proteins during adipocyte development.

We have constructed a recombinant bacterial library containing cDNA prepared from mRNA of adipose 3T3 cells. We have screened this library by several methods and isolated colonies containing sequences complementary to mRNAs for glycerophosphate dehydrogenase, two other major differentiation-dependent proteins of Mr = 28,000 and 13,000, and actin. These recombinants were identified by hybrid selection of total adipocyte mRNA, translation in vitro and subsequent immunoprecipitation, and two-dimensional electrophoresis of translated proteins. Three of the four cloned cDNAs hybridized to single adipocyte mRNA species of size close to that expected from the size of the polypeptide it specifies, but the mRNA for glycerophosphate dehydrogenase contained 3,550 bases, far larger than necessary to code for its polypeptide (Mr = 34,000). The increase in amount of mRNA during differentiation was 150-fold for the protein of Mr = 13,000 and considerably greater for glycerophosphate dehydrogenase and the protein of Mr = 28,000. The time course of mRNA accumulation was different for each of these mRNAs, indicating they do not respond synchronously during differentiation.

Adipose Tissue↗
PubMed1983

Properties of growth hormone receptors in relation to the adipose conversion of 3T3 cells.

Cultured preadipose 3T3 cells undergo a process of differentiation in which they convert to adipose cells. Growth hormone promotes this conversion. Since 3T3 sublines vary in their susceptibility to adipose conversion, it was of interest to examine the properties of the growth hormone receptors in relation to that susceptibility. It was found that preadipose 3T3-F442A cells, which are able to convert to adipose cells with high frequency, are able to bind about 10(4) growth hormone molecules per cell with Kd approximately 10(-9) M. After adipose conversion, no appreciable change in hormone binding was detected. The binding of growth hormone to 3T3-C2 cells (a line virtually insusceptible to adipose conversion) was indistinguishable from that to 3T3-F442A cells. Internalization and degradation of the hormone were also similar in the two cell lines. Susceptibility to adipose conversion is therefore not determined by the relative ability of the cells to bind or degrade the hormone, but must instead depend on some response, as yet unidentified, that follows binding of the hormone.

Adipose Tissue↗
PubMed1983

Gaining research access to retarded children in public schools.

The issue of gaining research access to mentally retarded children attending public schools is discussed. Preliminary steps completed prior to conducting a research investigation in the school settings were described within the framework of two independent studies. The important role of the special education teacher in conducting research in the natural environment is delineated.

Child↗