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Biomedical subjects

I W Craig

Publications and source records attributed to I W Craig.

At least 109 records · Page 6Linked to original sources
PubMed1982

Platelet monoamine oxidase: specific activity and turnover number in headache.

Monoamine oxidase turnover numbers (molecules of substrate converted to product per minute per active site) have been calculated for the human platelet enzyme using [3H]pargyline. Headache patients with high and low monoamine oxidase specific activities relative to controls were found to have turnover numbers very close to those for controls. This finding suggests that their specific activities vary because of differences in the concentration of active monoamine oxidase molecules, rather than differences in the ability of those enzyme molecules to catalyse the deamination reaction.

Binding Sites↗
PubMed1982

Immunological studies of human monoamine oxidases.

Antisera have been raised against monoamine oxidase preparations from human placenta and platelets. These antisera have been employed to characterize membrane-bound enzyme from a variety of human sources including liver, heart, and brain. The comparisons were based on a displacement radioimmunoassay system with soluble placental monoamine oxidase, previously labelled specifically with [3H]pargyline, as antigen. All forms of enzyme investigated demonstrated immunological cross reaction; however, the placental enzyme appeared to possess determinants not exhibited by the enzyme from the platelets or other tissues examined.

Blood Platelets↗
PubMed1981

Altered ribosomal RNA genes in mitochondria from mammalian cells with chloramphenicol resistance.

Chloramphenicol resistance in mammalian cells is cytoplasmically inherited. In yeast, a similar phenotype is caused by mutations in the mitochondrial DNA (mtDNA), and sequencing of carefully constructed strains has identified nucleotide monosubstitutions in the 3' region of the large (21S) rRNA gene which correlate with the antibiotic resistance. We have sequenced the corresponding section of mammalian mtDNA from chloramphenicol-resistant cell lines for comparison with the wild-type sequence. Differences between the sequences occur at positions similar to those altered in the yeast mutants, in a highly conserved region of the large (16S) rRNA gene.

Animals↗
PubMed1980

Assignment to chromosome 16 of a gene necessary for the expression of human mitochondrial glutamate oxaloacetate transaminase (aspartate aminotransferase) (E.C. 2.6.1.1.).

A gene necessary for the expression of human mitochondrial glutamate oxaloacetate transaminase (GOT-2) has been assigned to chromosome 16 on the basis of an immunochemical analysis of human-mouse somatic cell hybrids. Mitochondrial GOT cosegregates with adenine phosphoribosyl transferase (E.C. 2.4.2.7.).

Adenine Phosphoribosyltransferase↗
PubMed1979

Localisation of the G gamma-, A gamma-, delta- and beta-globin genes on the short arm of human chromosome 11.

Human-mouse somatic cell hybrids have proved invaluable in assigning human genes to their respective human chromosomes. To date, the success of this approach has depended on identifying human proteins which are synthesised in hybrid cells containing a small number of human chromosomes. Consequently, chromosome assignment has been limited mainly to human proteins which are expressed in man-mouse somatic cell hybrids and for which a suitable assay, usually electrophoretic or immunological, exists to distinguish between the human and murine homologous proteins. This technique is therefore unsuitable for the assignment of those human genes which are expressed only in differential cells and not in hybrid cells. Here, we describe how nucleic acid hybridisation and restriction endonuclease mapping of DNA can be combined to test for the presence of human structural gene sequences within hybrid cell DNA. This method can be used to assign any purified human DNA sequence to a human chromosome, and does not require the DNA sequence to be expressed in man-mouse hybrid cells.

Animals↗
PubMed1977

Assignment of the genes for human beta-glucuronidase and mitochondrial malate dehydrogenase to the region pter leads to q22 of chromosome 7.

In human fibroblast cultures derived from adults, clones of cells with a common chromosome rearrangement have been widely reported. Cells derived from one of these clones have been used in hybridization experiments using mouse cells to localize the genes for beta-glucuronidase and mitochondrial malate dehydrogenase on human chromosome 7. The results of this study indicate that the genes for these isozymes are located on the region pter leads to q22 of human chromosome 7.

Cell Line↗
PubMed1976

Assignment of a gene for tryptophanyl-transfer ribonucleic acid synthetase (E.C. 6.1.1.2) to human chromosome 14.

We describe a simple method for locating tryptophanyl-tRNA synthetase (E.C. 6.1.1.2) on cellulose acetate gels (Cellogel) following electrophoresis. Employing electrophoretic conditions which result in the separation of mouse and human tryptophanyl-tRNA synthetase, we have analyzed extracts of a number of independently derived mouse-human somatic cell hybrids and subclones derived from these hybrids for the presence of human tryptophanyl-tRNA synthetase. Electrophoretic patterns of hybrid extracts which contain human tryptophanyl-tRNA synthetase exhibit three bands. This is consistent with published evidence that the enzyme for mammalian cells is a homologous dimer. The electrophoretic patterns derived from some hybrids are unusual in that the human and hybrid bands of activity are more intense than the mouse band from the same hybrid. An analysis of hybrid cells and extracts indicates that human tryptophanyl-tRNA synthetase segregates with human chromosome 14 and with the only enzyme marker which has previously been assigned to this chromosome, nucleoside phosphorylase.

Amino Acyl-tRNA Synthetases↗
PubMed1976

Analysis of proteins synthesized in mitochondria of cultured mammalian cells. An assessment of current approaches and problems in interpretation.

1. The conditions which enable highly efficient utilization of [35S]methionine by cultured mammalian cells and the resolution of selectively labelled mitochondrial products are described. 2. Analysis of mitochondria purified from cells labelled in the presence or absence of inhibitors of cytoplasmic (or mitochondrial) protein synthesis indicated that about 5% of the [35S]methionine incorporated into mitochondrial proteins results from synthesis on mitoribosomes. 3. The electrophoretic profile of the detergent-solubilized proteins of mitochondrial isolated from cells which were labelled in the presence of 50 mug/ml emetine was similar to those obtained with extracts prepared by direct solbuilization of the intact cells after incorporation of label. 4. Pulse-labelling studies suggested that the components resolved by electrophoresis and autoradiography under the conditions described, apparently represent discrete and stable end products radiography under the conditions described, apparently represent discrete and stable end products of mitochondrial protein synthesis. No post-synthetic modification or degradation of these products was detected. 5. Erythromycin was found to suppress the synthesis of additional labelled products which were detected in extracts of one cell line, when analysed by procedures which normally detected only mitochondrially synthesized proteins. These additional bands were attributed to the synthetic activity of Mycoplasma.

Cell Line↗