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Biomedical subjects

H Harris

Publications and source records attributed to H Harris.

At least 163 records · Page 9Linked to original sources
PubMed1982

Suppression and reexpression of human intestinal-like alkaline phosphatase in intraspecific hybrids.

Expression of the gene locus which codes for a form of human intestinal alkaline phosphatase (ALP) has been analyzed in intraspecific somatic cell hybrids. Hybrids were constructed between D98/AH-2, a line of HeLa which ectopically synthesizes high levels of this ALP isozyme, and three different nonintestinal ALP-producing diploid lines. In chromosomally complete hybrids, expression of the ALP isozyme was initially suppressed, but on extended culture, reexpression occurred, as did limited chromosome loss. Results from extensive subcloning experiments showed that events leading to reexpression occurred at high frequency, and this ALP reexpression appeared to confer some selective advantage, direct or indirect, on the cells. In the fibroblast hybrids, reexpression of the intestinal-like ALP was always accompanied by new, high-level expression of liver/bone/kidney ALP, the product of a separate ALP gene locus. Thus expression of the one ALP locus is not excluded and, in fact, appears to be promoted by expression of the other in these cells.

Alkaline Phosphatase↗
PubMed1982

Variations in the activity of nucleolar organizers in different tissues, demonstrated by silver staining of human normal and leukemic cells.

A simple silver-staining technique that demonstrates those nucleolar organizing regions of metaphase chromosomes which are transcriptionally active during the preceding interphase (AgNORs) has been applied to cells obtained from the bone marrow and mitogen-stimulated peripheral blood lymphocyte cultures of hematologically normal individuals and patients with various forms of leukemia. In the majority of bone marrow cells from the normal controls and many of the patients, the number of cells with detectable AgNORs, and the staining intensities in those cells which were Ag+, were markedly reduced compared with the levels found in blood lymphocytes. The numbers of cells having satellite associations and the numbers of chromosomes participating in these associations also generally reflected the proportions of AgNORs present. When patterns of bone marrow silver staining were compared between patients with leukemia, distinct differences were found which could be correlated with cytology. It is suggested that different cell types have characteristic AgNOR staining profiles, reflecting specific regulation of ribosomal RNA synthesis in particular cell lineages. AgNOR staining may indicate, therefore, the predominant cell types that divide in the bone marrows of patients with different forms of leukemia.

Bone Marrow Cells↗
PubMed1982

Evolution of alkaline phosphatases in primates.

Alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] in placenta, intestine, liver, kidney, bone, and lung from a variety of primate species has been characterized by quantitative inhibition, thermostability, and immunological studies. Characteristic human placental-type alkaline phosphatase occurs in placentas of great apes (chimpanzee and orangutan) but not in placentas of other primates, including gibbon. It is also present in trace amounts in human lung but not in lung or other tissues of various Old and New World monkeys. However, a distinctive alkaline phosphatase resembling it occurs in substantial amounts in lungs from Old World monkeys but not New World monkeys. It appears that duplication of alkaline phosphatase genes and mutations of genetic elements controlling their tissue expression have occurred relatively recently in mammalian evolution.

Alkaline Phosphatase↗
PubMed1982

The analysis of malignancy by cell fusion. IX. Re-examination and clarification of the cytogenetic problem.

Previous experiments with crosses between malignant and diploid mouse cells had shown that the reappearance of malignancy in hybrids in which it was initially suppressed was associated in some cases with the elimination of the chromosomes 4 derived from the diploid parent cell. In others, however, this did not appear to be so. In the present study, we have re-examined the role of the diploid chromosomes 4 in the suppression of malignancy using natural polymorphisms of the centromeric heterochromatin to identify the parental origin of the chromosomes 4 in the hybrid cells. We now find that the diploid chromosomes 4 are indeed involved in the suppression of malignancy in all the tumours that we have examined, which include a carcinoma, a melanoma, a sarcoma and a lymphoma. In all crosses between these malignant tumour cells and diploid fibroblasts, there is selective pressure in vivo against the chromosomes 4 derived from the diploid cell and in favour of the chromosomes 4 derived from the malignant cell. This indicates that the chromosomes 4 in all these tumours are in some way functionally different from the chromosomes 4 of the diploid fibroblast. Reappearance of malignancy in hybrids in which it was initially suppressed may result from a reduction in the number of diploid chromosomes 4, an increase in the number of malignant chromosomes 4, or both. The gene on the diploid chromosome 4 responsible for the suppression of malignancy acts in a dose-dependent manner.

Animals↗
PubMed1981

Hexose transport in hybrids between malignant and normal cells.

The kinetic parameters of hexose uptake were measured in matched pairs of hybrids between malignant and normal cells. Each pair consisted of a hybrid in which malignancy was initially suppressed and a segregant tumour derived from it. Comparisons were also made between tumour cells and non-tumorigenic derivatives selected from the tumour cell populations in vitro. Without exception, malignancy, as defined by the ability of the cell to grow progressively in vivo, was found to be linked to a systematic decrease in the Michaelis constant of the hexose transport system.

Animals↗
PubMed1981

Modulation of the expression of alkaline phosphatase genes in a human malignant cell line passaged through nude mice.

Hep 2/5 cells, a clone of HeLa which expresses both placental-type alkaline phosphatase and fetal intestinal alkaline phosphatase (ALP), were grown as solid tumors in nude mice. Analysis of ALP isozymes present in tumor specimens excised at intervals over a 52-day period showed that levels of placental-type ALP had dropped markedly, while levels of the intestinal ALP remained fairly constant. Cells re-cultured from two separate tumors regained most of the original placental ALP levels. However, levels of the fetal intestinal ALP in cells returned to culture rapidly increased to more than six times the levels in the original cultured cells, and these increased levels persisted. Passage through nude mice thus induced at least semi-permanent changes in the level of expression of fetal intestinal ALP in Hep 2/5 cells, and the nature of these changes may relate to the role of the isozyme locus in malignant cells.

Alkaline Phosphatase↗
PubMed1981

Alkaline phosphatase expression in human cell lines derived from various malignancies.

A search for expression of heat-stable placental-type alkaline phosphatase (ALP) has been carried out in 19 unselected human tumor cell lines, known not to be HeLa. All cell lines showed measureable ALP activity and in 15 of the lines at least low levels of a heart-stable, presumptively placental-type ALP were detected. In five of these lines where the level of this heat-stable activity was sufficient, further, investigation, (immunologic, inhibition and electrophoretic studies) demonstrated that this ALP was placental-type in its characteristics and clearly different from liver/bone/kidney or intestinal ALPs. In 10 lines the heat-stable activity was too low to allow further characterization, In four lines no heat-stable activity in these various lines was liver-bone-kidney in type. This study suggests that the placental ALP locus may be expressed in at least at low levels in a much higher proportion of tumors and tumor cell lines than previously reported. The findings taken together with recent reports that low levels of placental-type ALP are present in some normal adult tissues (cervix, Goldstein et al., 1980; testis, Chang et al., 1980), indicate that so-called "ectopic" synthesis of placental ALP in tumor cells may not necessarily be due to derepression of a structural locus which is completely unexpressed in normal adult tissues. It may represent an enhancement of expression in malignancy or there may be clonal expansion of a particular cell type which normally expresses the alkaline phosphatase at a high level.

Adult↗
PubMed1981

Clobazam and diazepam in anxiety.

The anxiolytic effects of clobazam, diazepam, and placebo were compared in a 4-wk double-blind study of 159 anxious outpatients, primarily from family practice. Clobazam (30 to 80 mg/day) and diazepam (15 to 40 mg/day) were found to induce similar side effect, primarily sedation, and although both active drugs induced greater clinical improvement than placebo, clobazam induced the largest degree of improvement in most aspects. It was speculated that the relatively high daily dosage of diazepam may have been contributed to these results.

Adult↗
PubMed1981

Detection of enzyme polymorphism by using monoclonal antibodies.

Six monoclonal antibodies against human placental alkaline phosphate [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1], a highly polymorphic enzyme, were tested for reactivity against a panel of 295 placental extracts that had been typed electrophoretically. The products of the three common alleles as well as several rare alleles could be discriminated by the various antibodies. In some cases differences between allelic products were reflected by essentially "all-or-none" reactions, but in other cases the differences were smaller and demonstrable only by quantitative analysis of the binding. Evidence for allelic differences not detectable electrophoretically was also obtained.

Alkaline Phosphatase↗
PubMed1981

Estimation of genetic variation at the DNA level from restriction endonuclease data.

We consider the estimation of the genetic variation in a natural population when the data are obtained by the use of restriction endonucleases. Under the restriction endonuclease technique, a particular DNA segment is considered and cut wherever a recognition sequence appropriate to the endonuclease occurs. We consider data generated when a random sample of homologous DNA segments is treated in this way with one or a battery of restriction endonucleases. The numbers and sizes of the fragments that result indicate the locations and the frequencies of the recognition sequence (or, with a battery of restriction endonucleases, of each recognition sequence). These frequencies in the sample form the basis for an estimate of the amount of genetic variation in the population.

DNA↗
PubMed1981

Electrophoresis of enzyme--monoclonal antibody complexes: studies of human placental alkaline phosphatase polymorphism.

Enzyme--monoclonal antibody complexes formed between six different monoclonal antibodies and the six phenotypes of human placental alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] that represent the homozygous and heterozygous combinations of the three common alleles have been examined by electrophoresis in starch, acrylamide, and agarose gels. Since the complexes formed retain full enzyme activity, they could be detected after gel electrophoresis by an enzyme stain. Distinctive electrophoretic patterns were obtained with each monoclonal antibody. Differential binding of certain of the antibodies with the products of different alleles produces clear discrimination of various homozygous and heterozygous phenotypes. This discrimination parallels the results previously obtained by using a quantitative binding radioimmunoassay. The results show that this general method should prove useful in screening hybridoma fluids for the presence of monoclonal antibodies to specific enzymes; in the detection of allelic variation, even where this is not expressed by electrophoretic differences among the uncomplexed enzymes; and in discriminating between homozygotes and heterozygotes. It could also prove to be a useful tool in the elucidation of the molecular structures of enzyme--monoclonal antibody complexes.

Alkaline Phosphatase↗
PubMed1981

Mammalian brain alkaline phosphatase: expression of liver/bone/kidney locus. Comparison of fetal and adult activities.

The alkaline phosphatases (EC 3.1.3.1) are determined by at least three gene loci, which can be sharply distinguished one from another by their sensitivity to inhibition with various amino acids and peptides and by thermostability. Alkaline phosphatase is present in the brains of guinea pig, rat, mouse, hamster, squirrel, rabbit, cat, sheep, cow, tamarin, baboon, and man. The gene locus coding for alkaline phosphatase in all these brains is the liver/bone/kidney locus, as indicated by thermostability studies and by inhibition studies with L-phenylalanine, L-homoarginine, and L-phenylalanylglycylglycine. The average brain alkaline phosphatase activity is about 35% of the average for the livers and only 7.2% and 4.4% of the average kidney and placental activities, respectively. During growth and development, brain alkaline phosphatase activity decreases in the mammals studied. The amount of change is tissue- and species-dependent.

Age Factors↗
PubMed1981

Immunological delineation in normal and malignant cells of a membrane protein involved in glucose transport. II. Function of the antigen.

A review of the literature suggested that the antigen detected by the M/27 antibody described in the preceding paper might be involved in the transport of glucose across the cell membrane. This idea was tested by measuring the amount of M/27 antibody bound to cells under a range of conditions known to influence the rate of glucose uptake. Glucose starvation and the administration of insulin under appropriate conditions are known to increase the Vmax for glucose uptake in certain cells, and high cell density in vitro is known to decrease the Vmax. Glucose starvation was found to increase the amount of M/27 antigen present on the surface of 2 malignant cell lines, but produced no detectable change in 5 different non-malignant cell types. Insulin increased the amount of M/27 antigen on the surface of both malignant and non-malignant cells. At high cell density, the amount of M/27 antigen present on the cell surface decreased. The changes in the Vmax for glucose uptake produced by these manipulations have been shown not to require the synthesis of protein. This was also found to be true for the changes in M/27 antigen concentration. By disrupting cells in detergent, it could be shown that there was an intracellular pool of M/27 antigen. The total amount of M/27 antigen in the cell was found to be about 4 times as large as the amount of the antigen on the cell surface. This figure agrees with the value given in the literature for the size of the intracellular pool of the glucose transport system. The amount of M/27 antigen on the cell surface was found to vary during the cell cycle. A dramatic increase occurred early in S phase.

Animals↗
PubMed1981

Immunological delineation in normal and malignant cells of a membrane protein involved in glucose transport. I. Preparation and properties of the antibody.

Partially purified preparations of the 200000 Mr membrane glycoprotein described by Bramwell & Harris were used as antigens to generate monoclonal antibodies. Whether the protein was prepared from human or mouse tumours, the mice immunized with it yielded monoclonal antibodies of broadly similar specificities. All the antibodies obtained were of the immunoglobulin M class, despite a prolonged immunization schedule, and recognized an antigen that was present on the surface of mouse, rat and human cells. One such antibody, M/27, was studied in detail. With the exception of 2 rat kidney cell lines, the antigen detected by M/27 was found on the surface of all cells grown in culture, whether malignant or not. However, in the mouse, the species in which the antibody was generated, M/27 discriminated sharply between malignant tumours and normal tissues excised directly from the animal. In normal adult or embryonic mouse tissues, whether they were composed of multiplying cells or not, the antigen detected by M/27 was present on the cell surface only at the lower limit of detection, if at all. Malignant mouse tumours grown in the animal produced large amounts of the antigen. Explantation of embryonic mouse fibroblasts induced the expression of the antigen, which was not detected on these same cells in their normal habitat in the growing embryo. Conversely, non-malignant cells that express the antigen in vitro cease to do so when they are re-introduced into the animal. The antigenic determinant appeared to be polypeptide in nature rather than polysaccharide.

Animals↗