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Biomedical subjects

H Green

Publications and source records attributed to H Green.

At least 163 records · Page 9Linked to original sources
PubMed1979

Participation of one isozyme of cytosolic glycerophosphate dehydrogenase in the adipose conversion of 3T3 cells.

Growing surface cultures of 3T3 cells possess a low level of glycerophosphate dehydrogenase, an important enzyme in triglyceride synthesis. When 3T3-C2, a subline that does not undergo appreciable adipose conversion, reaches confluence, the level of the enzyme does not increase. In 3T3-F442A, a subline that undergoes the conversion with high frequency, the specific activity of the enzyme increases about 600-fold. The enzyme of the adipose 3T3 cells is different from that of non-adipose 3T3 cells in its thermal stability and its affinity for dihydroxyacetone phosphate. The enzyme of the adipose cells probably corresponds to the stable "adult" form of the enzyme, as described previously, and the enzyme of non-adipose 3T3 cells is probably the unstable "embryonic" form. For this reason, the change in the enzyme that takes place during the adipose conversion is greater than would be indicated simply by the total increase in specific activity. If, as seems likely, the two forms of glycerophosphate dehydrogenase are the products of independent genes, the adipose conversion may activate a hitherto silent gene for the stable enzyme.

Adipose Tissue↗
PubMed1979

Massive hemoptysis secondary to flow-directed thermodilution catheters.

Hemoptysis is an unusual complication of flow-directed (Swan-Ganz) catheters. Over-inflation of the balloon with a shearing-induced rupture of a small pulmonary artery, and the spear effect of the catheter tip appear to be the mechanisms in the two cases presented. Diligent care to avoid overinflation of the balloon in the pulmonary capillary wedge position by observation of the pressure waveform is critical. The spear effect that is frequently seen during insertion may be eliminated by deflating the balloon at the first appearance of the pulmonary artery waveform and gradual advancement of the catheter five to eight cm, when the balloon is then reinflated to obtain the wedge.

Aged↗
PubMed1979

Presence in human epidermal cells of a soluble protein precursor of the cross-linked envelope: activation of the cross-linking by calcium ions.

Late in the terminal differentiation of epidermis and cultured epidermal cells, a protein envelope located beneath the plasma membrane becomes cross-linked by cellular transglutaminase. The process of cross-linking can be initiated in cultured epidermal cells by agents affecting cell membrane permeability--nonionic detergents, high salt concentrations and ionophores. These agents initiate the cross-linking process by making calcium ions available to the transglutaminase. A soluble precursor of the cross-linked envelope has been identified in crude extracts of cultured epidermal cells by its ability to incorporate labeled amines through the action of transglutaminase. The protein has been purified to homogeneity by gel filtration and chromatography on columns of DEAE-cellulose and hydroxyapatite. Comprising an estimated 5--10% of the soluble cell proteins, it has a molecular weight of about 92,000, is isoelectric at pH 4.5 +/- 0.3 and has an unusual amino acid composition (46% Glx residues). It is chemically and immunochemically unrelated to keratins. The following evidence confirms that the protein becomes incorporated into cross-linked envelopes: first, washed cross-linked envelopes bind antibody to the purified protein, as shown by indirect immunofluorescence; second, absorption of the antiserum with washed envelopes removes all detectable antibodies to the purified protein; and third, the protein cannot be extracted from keratinocytes after their envelopes have become cross-linked. Examination of sections of epidermis by immunofluorescence, using antiserum to the purified protein, reveals that in addition to the stratum corneum, the living cells of the outer half of the spinous layer react strongly. The envelope precursor is present in the cytoplasm, but becomes concentrated at the cell periphery, where it will be cross-linked later, when the cells have passed through the granular layer. The protein is also concentrated in a peripheral location in cultured epidermal cells.

Amino Acids↗
PubMed1979

A study of the adipose conversion of suspended 3T3 cells by using glycerophosphate dehydrogenase as differentiation marker.

The adipose conversion of 3T3 cells has been examined in stabilized suspension cultures. In 3T3-F442A cells, glycerophosphate dehydrogenase (sn-glycerol-3-phosphate: NAD(+) 2-oxidoreductase, EC 1.1.1.8), a key enzyme in triglyceride synthesis, increases in specific activity by more than 5000-fold and can be used as a sensitive and precise measure of the conversion. The conversion depends on an adipogenic factor present in the serum, and this factor can be assayed by the cellular enzyme response. If the cells are growing at the time they receive the adipogenic factor, the enzyme response does not become detectable until after 3 days, during which the cells first enter a resting state. If the cells are resting at the time they receive the adipogenic factor, the enzyme activity begins to increase in 24 hr or less. Only resting cells seem susceptible to the reprogramming of their differentiated state necessary for the adipose conversion. Once the conversion begins, the increase in enzyme activity is exponential over at least 2 orders of magnitude. When cells in a resting state begin the adipose conversion, their biosynthetic processes are accelerated: the rate of protein synthesis increases, they accumulate cell protein, and they may replicate their DNA and divide. The cell multiplication is not essential for adipose conversion but is a form of clonal selection that increases the proportion of adipose cells relative to nonadipose cells.

Adipose Tissue↗
PubMed1979

Growth of cultured human epidermal cells into multiple epithelia suitable for grafting.

Owing to several recent developments, the cultivability of epidermal keratinocytes, particularly those of the human, has been greatly improved. Under the conditions used, single cultured cells generate stratified colonies that ultimately fuse and form an epithelium that is reasonable approximation of the epidermis. It will be shown here that large amounts of cultured epithelium can be generated from a small piece of epidermis in a short time. We wish to bring to the attention of surgeons and cell biologists the possibility of using culture-grown epithelium derived from the same individual to restore defects in the epidermis.

Age Factors↗
PubMed1979

Keratin cytoskeletons in epithelial cells of internal organs.

An antiserum against human epidermal keratins was used to detect keratins in frozen sections of various rabbit and human tissues by indirect immunofluorescence. Strong staining was observed in all stratified squamous epithelia (epidermis, cornea, conjunctiva, tongue, esophagus, vagina, and anus), in epidermal appendages (hair follicle, sebaceous gland, ductal and myoepithelial cells of sweat glands), as well as in Hassall's corpuscles of the thymus, indicating that all contain abundant keratins. No staining by the antiserum was observed in fibroblasts, muscle of any type, cartilage, blood vessel, nerve tissue, iris or lens epithelium, or the glomerular or tubular cells of the kidney. In contrast, the antiserum stained the cells of most epithelia of the intestinal tract, urinary tract (urethra, bladder, ureter, collecting ducts of kidney), female genital tract (cervix, cervical glands, uterus, and oviduct), and respiratory tract (trachea and bronchi). Epithelial cells of the fine ductal system in the pancreas and submaxillary gland also stained well. When primary cultures of epithelial cells derived from bladder, intestine, kidney, and trachea were grown on glass coverslips and stained with anti-keratin, fiber networks similar to those of cultured keratinocytes were observed. These results show that keratins constitute a cytoskeleton in epithelial cells of diverse morphology and embryological origin. The stability of keratin filaments probably confers the structural strength necessary for cells covering a free surface. Keratin staining can be used to obtain information about the origin of cell lines.

Animals↗
PubMed1979

Alterations in ventilation and gas exchange during exercise-induced carbohydrate depletion.

The relationship between ventilation (VE), oxygen consumption (VO2), and carbon dioxide production (VCO2) during work were studied in four trained males during exercise-induced carbohydrate depletion. Repeated bouts of heavy treadmill exercise (6 min at 95% VO2 max) were performed once per hour for 24 h in order to promote a shift in energy substrate from carbohydrate to fat. Measurements of VO2 and VCO2 recorded during each minute indicated that VO2 was unaffected by the number of runs, whereas VCO2 showed a progressive reduction which amounted to 24% during the final run. A corresponding decline of 19% was observed in the respiratory exchange ratio. No significant change in VE occurred between any of the runs. It is concluded that during heavy, repeated, muscular exercise, reductions in VO2, strongly suggestive of an increased fat oxidation, are not accompanied by a corresponding change in ventilation.

Adult↗
PubMed1978

Pattern formation by cultured human epidermal cells: development of curved ridges resembling dermatoglyphs.

In cultures made from disaggregated human epidermal cells, growth to a confluent cell layer is followed by the emergence of patterns resembling those of human dermatoglyphs. These patterns reflect intrinsic properties of kertinocytes. In vivo, only the epidermis of the volar surfaces forms patterns, but in culture, patterns are formed by epidermal cells from other sites as well. Patterns develop by a process of cell movement which first produces ridges and then curves the ridges into figures of increasing complexity, ultimately whorls.

Cell Differentiation↗
PubMed1978

Keratin filaments of cultured human epidermal cells. Formation of intermolecular disulfide bonds during terminal differentiation.

Human epidermal cells grown in culture synthesize abundant keratins. These keratins are similar to those of stratum corneum of human epidermal callus in their insolubility in dilute aqueous buffers, their molecular weight range of 40,000 to 60,000, their immunolgical reactivity, and their ability to assemble into 80 A tonofilaments in vitro; but there are differences in the molecular weights of some of the proteins, the number of components, and their charge heterogeneity, related at least in part to phosphorylation. About 30% of all the proteins of living cultured keratinocytes consists of keratins, compared with over 85% of stratum corneum. All the keratins of human stratum corneum were found to be cross-linked by intermolecular disulfide bonds while most keratins of the living cells were not. As the cells mature in Methocel-stabilized suspension culture, their keratins become increasingly disulfide cross-linked. When uncross-linked tonofilaments of living keratinocytes are dissolved in 8 M urea and the filaments reconstituted in vitro their keratins become disulfide cross-linked under aerobic conditions and consequently insoluble in solutions of 8 M urea or sodium dodecyl sulfate. The results indicate that the uncross-linked state of the keratins in living cells is due to the reducing intracellular environment and not to a precursor state related to the primary structure of the proteins. The disulfide cross-links stabilizing the keratin filaments must be distinguished from the epsilon-(gamma-glutamyl)lysine cross-links stabilizing the cornified cell envelope.

Cell Differentiation↗
PubMed1978

Immunofluorescent staining of keratin fibers in cultured cells.

Antibody prepared against a group of keratins purified from human stratum corneum was used to identify cells containing keratins by immunofluorescence. In sectioned tissue and in culture, keratinocytes of skin and other stratified squamous epithelia-whether human, rabbit of mouse-stained strongly, indicating homologous amino acid sequences in the keratins of these species. In all cases, the antibody revealed a dense cytoplasmic network of discrete fibers probably consisting of aggregated (tono-) filaments. The pattern of staining was not affected by cytochalasin B or colcemid. No keratins were detected in cultured cells of mesenchymal origin (3T3, NIL, BHK, human diploid fibroblasts) or in connective tissues, indicating that the 100 A filaments of fibroblasts are not related to the keratins. Keratinocytes at all stages of differentiation, including basal cells, stained brightly and therefore contained abundant keratins.

Animals↗
PubMed1978

Cyclic AMP in relation to proliferation of the epidermal cell: a new view.

Four agents known to increase the level of cellular cAMP by different means (cholera toxin, dibutyryl cAMP, methyl isobutyl xanthine and isoproterenol) increase the growth of colonies of cultured human epidermal cells and of keratinocytes derived from other stratified squamous epithelia. This effect is due to an increase in the overall rate of cell proliferation in the colonies. When added to cultures under hitherto optimum conditions for epidermal cell growth [in the presence of supporting 3T3 cells and epidermal growth factor (EGF)], most of the agents exert an effect of considerable magnitude, the toxin being the most potent. Since the toxin exerts an effect in the absence of supporting 3T3 cells, it must be able to act directly on the keratinocytes. It can also act in the absence of ECF and of medium conditioned by 3T3 cells, although proliferation is greatest when supporting 3T3 cells and EGF are present. The increased proliferation in the presence of the toxin is associated with an increased proportion of small cells known to include the multiplying fraction. The use of toxin makes the cultivation of keratinocytes from epidermis and other stratified squamous epithelia much easier and prolong the culture life of the cells. Whether cell proliferation in the intact epidermis is regulated through agents affecting cAMP (in a direction opposite to that suggested by much of the earlier literature) remains to be elucidated, but the existence of such a mechanism in cultured cells suggests that it may function in the intact epithelium.

1-Methyl-3-isobutylxanthine↗
PubMed1978

The expression of keratin genes in epidermis and cultured epidermal cells.

Cultured human epidermal cells and human stratum corneum (callus) contain a number of keratins of different molecular size, but the size distribution is not the same in the two cases. To characterize these keratins in more detail, we compared them by amino acid analysis, immunological reactivity and one-dimensional peptide mapping (Cleveland et al., 1977). No differences in amino acid compositon could be detected among keratins of stratum corneum differing in molecular size by as much as 50%, suggesting that some repeating structure may be present in these molecules. Examination of polypeptide fragments produced by partial enzymatic hydrolysis showed strong similarities among all the keratins of stratum corneum and of cultured epidermal cells, even extending to the keratins of rodents; but the keratins of similar size, whether of stratum corneum or cultured cells, were more closely related than keratins of different size. This conclusion was supported by studies of the immunological reactivity of the keratins. How the epidermal cell generates a family of keratins is a problem of considerable interest. The differences in size and structure between the keratins of stratum corneum and cultured epidermal cells suggest that the epidermal cell can modify the expression its keratin genes.

Amino Acids↗