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Biomedical subjects

C Jones

Publications and source records attributed to C Jones.

At least 703 records · Page 39Linked to original sources
PubMed1977

Isolation of a lactic dehydrogenase-A-deficient CHO-K1 mutant by nylon cloth replica plating.

A mutant Chinese hamster ovary cell deficient in lactate dehydrogenase A activity has been isolated using a nonselective technique. The method uses histochemical staining to examine colonies directly for enzyme activity and nylon cloth replica plating to recover particular clones. The mutant cell has an apparent Km (pyruvate to lactate) that is nearly tenfold higher than the parental cell, while its Vmax has been reduced more than 80-fold. In mutant cell extracts with added porcine LDH-B enzyme, molecular dissociation and recombination of subunits produces two new active LDH tetramers (A1B3, A2B2). The electrophoretic mobility of at least one of the tetramers (A1B3) was different from those formed in the parental extracts. The evidence suggests the variant cell contains a mutation in the structural gene for LDH-A.

Cell Line↗
PubMed1977

Further studies on hybrid cell-surface antigens associated with human chromosome 11.

A new human immunogenetic cell-surface activity associated with human chromosome 11 in the AL human-Chinese hamster ovary cell hybrid is described. Like a1, but not a2, it is present on the human erythrocyte. By mutagenesis and selection, specific, stable, variants of the AL hybrid have been prepared exhibiting various combinations of a1, a2, a3, and lactic dehydrogenase A activities. The antigens of the AL system can be demonstrated by the horseradish peroxidase system which offers a promising approach to scanning of tissue cells.

Antibody Specificity↗
PubMed1977

Genetics of cell-surface antigens: regional mapping of three components of the human cell-surface antigen complex, AL, on chromosome 11.

Cytogenetic analysis has been performed on a series of deletion mutations on human chromosome 11 of AL hybrid clones in which specific markers have been lost as a result of treatment with mutagenic agents. Such analysis has localized the three previously identified components of the AL cell-surface antigen complex to the indicated regions of chromosome 11: a1 and a3:11p13 leads to 11pter; a2:11q13 leads to 11qter. Using these methodologies human lactic dehydrogenase A localization on the short arm as reported by others has been confirmed. Evidence is presented provisionally assigning this gene to 11p13 leads to 11pter.

Antigens↗
PubMed1977

Further structural studies of the heavy chain of HLA antigens and its similarity to immunoglobulins.

The papain-solubilized fragment of the heavy chain of HLA-B7, which is the NH2-terminal part of the whole polypeptide chain, can be divided into three regions by mild acid and cyanogen bromide cleavages. The first 100 amino acids terminating in a methionine residue contain the carbohydrate moiety; this segment is followed by two others of molecular weights 9,999 and 13,000, each containing an intrachain disulfide bridge. The two intrachain disulfide bridges are separated by a stretch of amino acids containing an acid-labile aspartyl-prolHLA-2, A28, and AW25 contain this acid-labile peptide bond in their larger subunit. Sequencing from the acid cleavage site of HLA-7 through the third half-cystine revealed consideralbe homology with amino acid sequences around a half-cystine in immunoglobulin variable regions.

Amino Acid Sequence↗
PubMed1977

Pericarditis complicating a case of meningococcal meningitis.

The case is described of an 18-year-old schoolboy who developed pericarditis during the course of meningococcal meningitis; he had evidence of a preceding chronic meningococcaemia. Good recovery followed on systemic antibiotics only. The pericarditis was probably a direct septic complication of meningococcal meningitis.

Adolescent↗
PubMed1977

Synteny between glycinamide ribonucleotide synthetase and superoxide dismutase (soluble).

The auxotrophic mutant ade -C derived from Chinese hamster ovary cell CHO-K1 lacks the enzyme glycinamide ribonucleotide synthetase and requires exogenous supplement of purines for growth. Cells from this mutant were fused with normal human lymphocytes, and the resulting hybrids were isolated in purine-deficient medium. A total of 32 primary clones and 49 secondary clones were analyzed for various isozyme markers. Cytogenetic analysis with chromosome banding was also performed in some hybrid clones. The results provide evidence indicating that glycinamide ribonucleotide synthetase is syntenic with superoxide dismutase (soluble) and is located on human chromosome 21.

Animals↗
PubMed1976

Thyrotoxic vomiting.

In seven patients vomiting played an important part in the presentation of thyrotoxicosis. Vomiting does not always indicate severe thyroid disease, and the diagnosis in patients presenting with this symptom may be long delayed.

Adult↗
PubMed1976

Isolation of mutants lacking branched-chain amino acid transaminase.

Variants of the Chinese hamster ovary cell have been isolated which can no longer grow when valine, leucine, or isoleucine is replaced in the culture medium by its respective alpha-keto acid: alpha-ketoisovaleric acid, alpha-ketoisocaproic acid, or alpha-keto-beta-methylvaleric acid. These variants lack branched-chain amino acid transaminase activity. Evidence is presented indicating these variants to be single gene mutants. Genetic evidence is also presented confirming previous biochemical evidence that a single enzyme carries out transaminase functions on valine, leucine, and isoleucine. The branched-chain transaminase-deficient (trans-) mutants can be reverted to wild-type behavior by treatment with mutagenic agents. These mutants promise to be useful in exploring regulatory mechanisms in biochemical, genetic, and cancer research.

Cell Line↗
PubMed1976

Biochemical genetics of Chinese hamster cell mutants with deviant purine metabolism: isolation, selection, and characterization of a mutant lacking hypoxanthine-guanine phosphoribosyltransferase activity by nutritional means.

Mutants of the Chinese hamster ovary cell derived from CHO-K1 have been selected for lack of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) (HGPRT) without the use of a drug-resistance protocol. The procedure depends on the use of a parental strain carrying a mutation making it unable to synthetize purines and thus dependent upon exogenously added purines for growth. The standard "BUdR-visible-light" procedure is then used to select those cells which can use adenine but cannot use hypoxanthine as a purine source. These cells are shown to be thioguanine resistant, to be unable to incorporate exogenously added hypoxanthine into purine nucleotides, to complement our other adenine-specific purine auxotrophs, Ade-H and Ade-I but not to complement a cell isolated by virtue of thioguanine resistance, and to lack the activity of HGPRT. The use of such multiply marked mutants and cells related to them for further analysis of purine nucleotide biosynthesis and interconversion is discussed.

Animals↗
PubMed1976

Genetics of somatic mammalian cells: genetic, immunologic, and biochemical analysis with Chinese hamster cell hybrids containing selected human chromosomes.

Through hybridization of specific Chinese hamster cell auxotrophs with human cells and selection in media lacking the nutritional supplements required by the former cells, a series of stable hybrid clones can be prepared. These hybrids have genomes consisting of a common part--the complete or almost complete set of Chinese hamster chromosomes, plus a variable part--one or a few human chromosomes. The identity of the human chromosomes can be varied by utilizing different Chinese hamster auxotrophs and the appropriate selective media. The human chromosomes present can be determined by a combination of cytogenetic analysis with chromosome banding and testing for specific human marker genes. Hybrids containing single human chromosomes 11 and 12 and the combination of both 11 and 12 are described. The system appears to lend itself to various studies such as identification of human cell surface antigens, determination of their chromosomal loci, measurement of their distribution among cells of normal human tissues, study of interrelations among syntenic and asyntenic genes, and mutational analysis of the human genome.

Animals↗