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Biomedical subjects

D C Wallace

Publications and source records attributed to D C Wallace.

At least 217 records · Page 12Linked to original sources
PubMed1981

Maternal inheritance of mitochondrial DNA polymorphisms in cultured human fibroblasts.

We have isolated the total cellular DNA from the cultured diploid fibroblasts of a six-member, three-generation human family. Using a specific radioactive probe for mitochondrial (mt) sequences we have identified new polymorphic variants in this family for the Hhal restriction endonuclease cleavage pattern of the mtDNA. The inheritance of these cleavage patterns verifies the maternal inheritance of mtDNA through all three generations.

Adolescent↗
PubMed1981

Mitochondrial DNA of chloramphenicol-resistant mouse cells contains a single nucleotide change in the region encoding the 3' end of the large ribosomal RNA.

The complete DNA sequence of the rRNA genes of mouse L cell mtDNA provides a basis for the examination of the nucleotide sequence of this region in a mutant mouse cell line that is resistant to chloramphenicol, a known inhibitor of mitochondrial protein synthesis. Resistance to chloramphenicol (CAPr) is conferred by a cytoplasmic determinant that is linked to mtDNA restriction endonuclease site polymorphisms. We have determined the sequence of a 212-nucleotide region of mtDNA from a CAPr mouse cell line that encodes a portion of the 1582-nucleotide large rRNA. This sequence is located 107-318 nucleotides from the 5' end of the heavy strand coding sequence, which corresponds to the 3' end of the rRNA. There is a single nucleotide difference in the large rRNA gene from CAPr cells, an A-to-G transition 243 nucleotides from the 5' end of the coding sequence. This single transition is located within a region of 10 nucleotides tht is otherwise completely homologous to human and yeast mitochondrial large rRNAs and Escherichia coli 23S rRNA and is positioned immediately adjacent to a single nucleotide transversion known to occur in a yeast CAPr mutant. This characterization of a mammalian mitochondrial mutant at the nucleotide level directly demonstrates that a mutant phenotype may result from a single mtDNA nucleotide change in an animal cell.

Animals↗
PubMed1981

Ethnic variation in Hpa 1 endonuclease cleavage patterns of human mitochondrial DNA.

The mtDNAs of 235 individuals from five ethnic groups were analyzed for restriction site variation by digestion with restriction endonuclease Hpa I, Southern transfer, and hybridization with 32P-labeled human mtDNA. Six different cleavage patterns (morphs) were found, all of which could be related to each other by single nucleotide substitutions. Differences were found in the frequency of these morphs among the populations. The largest difference observed was in the frequency of the morph most common in Caucasians and Orientals compared to the frequency of that found in Africans. This difference apparently originated by the sequence change G-T-C-A-A-C to G-T-T-A-A-C. This alteration permitted recognition by Hpa I but did not alter the amino acid sequence. Two other observed differences were due to separate substitutions occurring in the ribosomal RNA genes. Comparison with primate data shows that the morph with two fragments, found in 12.5% of Oriental and 4% of Bantu samples, might be the ancestral type common to all hominoids. These two conserved sites were localized in tRNA genes in the anticodon loop. Assuming that the two-fragment morph is ancestral, this finding is consistent with previous data suggesting that Asia is genetically central to the radiations that are thought to have given rise to the human ethnic groups.

Animals↗
PubMed1981

Assignment of the chloramphenicol resistance gene to mitochondrial deoxyribonucleic acid and analysis of its expression in cultured human cells.

The mitochondrial deoxyribonucleic acids (mtDNA's) from human HeLa and HT1080 cells differed in their restriction endonuclease cleavage patterns for HaeII, HaeIII, and HhaI. HaeII digestion yielded a 9-kilobase fragment in HT1080, which was replaced by 4.5-, 2.4-, and 2.1-kilobase fragments in HeLa. HaeIII and HhaI yielded distinctive 1.35- and 0.68-kilobase HeLa fragments. These restriction endonuclease polymorphisms were used as mtDNA markers in HeLa-HT1080 cybrid and hybrid crosses involving the cytoplasmic chloramphenicol resistance mutation was used. mtDNA's were purified and digested with the restriction endonucleases, the fragments were separated on agarose gels, and the bands were detected by ethidium bromide staining and Southern transfer analysis. Three cybrids and four hybrids (four expressing HeLa and three expressing HT1080 chloramphenicol resistance) contained 2- to 10-fold excesses of the mtDNA of the chloramphenicol-resistant parent. One cybrid, which was permitted to segregate chloramphenicol resistance and was then rechallenged with chloramphenicol, had approximately equal proportions of the two mtDNA's. Only one hybrid was discordant. These results indicated that chloramphenicol resistance is encoded in mtDNA and that expression of chloramphenicol resistance is related to the ratio of chloramphenicol-resistant and -sensitive genomes within cells.

Chloramphenicol Resistance↗
PubMed1980

Characterization of mitochondrial DNA in chloramphenicol-resistant interspecific hybrids and a cybrid.

We have examined the restriction endonuclease cleavage patterns exhibited by the mitochondrial DNAs (mtDNA) of four chloramphenicol-resistant (CAPR) human x mouse hybrids and one CAPR cybrid derived from CAPR HeLa cells and CAPS mouse RAG cells. Restriction fragments of mtDNAs were separated by electrophoresis and transferred by the Southern technique to diazobenzyloxymethyl paper. The covalently bound DNA fragments were hybridized initially with 32P-labeled complementary RNA (cRNA) prepared from human mtDNA and, after removal of the human probe, hybridized with mouse [32P]cRNA prepared from mouse mtDNA. Three hybrids which preferentially segregated human chromosomes and the cybrid exhibited mtDNA fragments indistinguishable from mouse cells. One hybrid, ROH8A, which exhibited "reverse" chromosome segregation, contained only human mtDNA. The pattern of chromosome and mtDNA segregation observed in these hybrids and the cybrid support the hypothesis that a complete set of human chromosomes must be retained if a human-mouse hybrid is to retain human mitochondrial DNA.

Animals↗
PubMed1980

Maternal inheritance of human mitochondrial DNA.

Human mitochondrial DNA was obtained from peripheral blood platelets donated by the members of several independent families. The samples were screened for nucleotide sequence polymorphisms between individuals within these families. In each family in which we were able to detect a distinctly different restriction endonuclease cleavage pattern between the parents, the progeny exhibited the maternal cleavage pattern. Informative polymorphisms were detected for Hae II (PuGCGCPy) in a three-generation family composed of 33 members, for HincII (GTPyPuAC) in a two-generation family composed of four members, and for Hae III(GGCC) in a two-generation family composed of four members. The Hae II polymorphism was analyzed through all three generations in both the maternal and paternal lines. The results of this study demonstrate that human mitochondrial DNA is maternally inherited. The techniques described for using peripheral blood platelets as a source of human mitochondrial DNA represent a convenient way to obtain data on mitochondrial DNA variation in both individuals and populations.

Blood Platelets↗
PubMed1978

Perhexiline maleate in the treatment of angina pectoris. Five years of personal clinical experience.

A five-year personal experience of the use of perhexiline maleate (Pexid) in the treatment of severe angina pectoris is presented. Ninety-four patients, all severely incapacitated by cardiac pain, received perhexiline maleate for an average period of 12.2 months. Perhexiline maleate was used either alone or, more commonly, in conjuction with other antianginal therapy, such as beta-adrenergic receptor blocking agents. The results demonstrate that perhexiline maleate is a very effective agent which appears to be safe for long-term usage. Side effects have been frequent, and occasionally bothersome, but all have been transient and dose-dependent. The possibility that the regimens of treatment may materially improve long-term prognosis is raised.

Adrenergic beta-Antagonists↗
PubMed1978

A linkage study of the loci for Huntington's disease and some common polymorphic markers.

The phenotypic frequencies of 24 polymorphic blood markers in a sample of patients with Huntington's disease (HD) have been compared with those in a sample of healthy Australian volunteers in an effort to detect any associations between HD and the markers concerned. The Rh factor, c, has a significantly lower frequency in the HD sample while ACP1c and Gm1,2 have a significantly higher frequency. The linkage relations of the HD locus have been analysed with respect to the various marker loci concerned. This analysis involved the development of methods to overcome the general lack of genetic data concerning the affected parent and the possibility that presently unaffected offspring may be asymptomatic carriers of the HD gene. The results suggest that close linkage between the HD locus and Fy, ADA, ACP1, Gc or Bg is highly unlikely. They also suggest a low probability of close linkage to ABO, Rh, Jk, Lu, AK1, PGM1 or C3. Positive linkage scores were obtained for P, Hp and Gm. The results are inconclusive for MNSs, K, Le, Se, GPT and Inv. The available data were uninformative for linkage between the HD locus and Co, 6-PGD or E1.

Australia↗
PubMed1977

Group education after myocardial infarction: Is it effective?

An analysis of the results of a study of a group of post-infarction patients who had received group instruction concerning the nature of myocardial infarction, compared with patients not so instructed, is presented. Contrary to expectation, anxiety levels as measured by the Catel IPTA Anxiety Scale were significantly higher in patients who experienced group education. Regardless of this finding, patients were subjectively appreciative of education.

Adult↗
PubMed1977

Mitotic segregation of cytoplasmic determinants for chloramphenicol resistance in mammalian cells. I: Fusion with mouse cell lines.

The segregation of cytoplasmically inherited chloramphenicol (CAP) resistance in mouse cells was investigated in fusions between CAP-resistant cells or cytoplasts (enucleated cells) and CAP-sensitive cells of varying tissue origin. All hybrids formed in cell-cell fusions were initially CAP-resistant, indicating that CAP resistance is dominant. Hybrids from fusions of cells of the same tissue origin (homologous) were stably CAP-resistant, whereas the hybrid population from fusions of different origins (heterologous) showed a rapid diminution of average CAP resistance. Individual hybrid clones from these heterologous fusions also showed an overall loss of CAP resistance, and a wide variation in CAP resistance which is consistent with a large number of genetic determinants (possibly mitochondrial DNA molecules) contributing to the CAP phenotype. Similar results were obtained from cytoplast-cell fusions, so the observed CAP segregation is not the result of nuclear-nuclear interactions. This segregation of CAP resistance constitutes a second criterion of cytoplasmic inheritance in mammalian cells.

Animals↗
PubMed1977

Mitotic segregation of cytoplasmic determinants for chloramphenicol resistance in mammalian cells II: Fusions with human cell lines.

Cytoplasmically inherited chloramphenicol (CAP) resistance in human cells has been used to study the interaction between sensitive and resistant mitochondria. Cybrids between two HeLa cells were stable for resistance, grew rapidly and cloned well in CAP, and were O2 tolerant. HeLa-HeLa hybrids were also stable up to 70 doublings in the absence of CAP. Cybrids between HeLa and WI-L2 cells were unstable for resistance for up to 40 doublings, grew slowly and cloned poorly in CAP, and were O2 sensitive (S phase). The growth rate then increased and the cells became stable for resistance, cloned well, and were not O2 sensitive (F phase). Doubling time for S but not F phase cells was proportional to CAP concentration, indicating that both kinds of mitochondria were present and functioning. The instability of CAP resistance in many interstrain but not in intrastrain mouse and human cybrids and hybrids is interpreted in relation to lower eukaryotes.

Cell Cycle↗
PubMed1976

Cytoplasmic inheritance in mammalian tissue culture cells.

A series of intraspecific, interspecific and interorder somatic cell cybrids and hybrids have been prepared by fusions in which one of the parents contained the cytoplasmically inherited marker for chloramphenicol (CAP) resistance. A clear relationship has been established between the expression of the CAP-resistant (CAP-R) determinants in the fusion products and the genetic homology of the parents. With increased genetic divergence, the acceptability of the CAP-R mitochondria decreased. Intraspecific cybrids and hybrids of the same strain were stable for the CAP-R marker, while those between strains were stable only in CAP. Intergeneric mouse-hamster cybrids occurred at a high frequency but were unstable in CAP, while CAP suppressed hybrid formation 100-fold. Interorder cybrids (CAP-R human X CAP-S mouse) occurred either at a moderate frequency and were stable at a low frequency and were unstable in CAP. Interorder hybrids could only be formed by challenging HAT-selected hybrids with CAP or by direct selection in ouabain and CAP. Reciprocal interorder crosses between CAP-R mouse and CAP-S human cells were unsuccessful. Interspecific cybrids contain only the chromosomes of the CAP-S parent. Interspecific hybrids selected directly in CAP segregated the chromosomes of the CAP-S parent, while hybrids selected in HAT and then CAP segregated those of the CAP-R parent. The mitochondrial DNA(mtDNA) of all mouse-human cybrids and most HAT and then CAP-selected hybrids contain only the mtDNA of the CAP-S mouse parent. However, preliminary evidence suggests that one of these hybrids contains both mouse and human mtDNA sequences.

Animals↗
PubMed1976

The social effect of Huntington's chorea on reproductive effectiveness.

An attempt has been made to account for the observed departures from a model of a simple single-locus inheritance in Huntington's Chorea. It is postulated that an indirect effect of the abnormal allele lies in its social effects on individuals in the family group whether they bear the allele or not. This acts by influencing their mate-finding and reproductive behaviour so as to produce the observed statistical anomalies.

Alleles↗
PubMed1975

Thrombotic thrombocytopenic purpura in four siblings.

A family is described in which four members of a sibship of seven suffered from a hematologic and systemic disorder whcih has been fatal in three and has been proved at autopsy to have been fatal in three and has been proved at autopsy to have been thrombotic purpura. The fourth member has probably suffered the same disorder. The clinical laboratory and genetic features of the family are discussed at length. No cause of the disorder has been determined.

Adrenal Glands↗
PubMed1975

Cytoplasmic transfer of chloramphenicol resistance in human tissue culture cells.

The cytoplasmic inheritance of human chloramphenicol (cap) resistance has been demonstrated by removing the nuclei of cells of the CAP-resistant HeLa strain 296-1 (enucleation) and fusing them to a CAP-sensitive HeLa strain lacking nuclear thymidine kinase. Plating the fusion products in bromodeoxyuridine and CAP resulted in the growth of about 150 colonies/10(6) parent cells plated. Permanent cell lines (cybrids) grown from such fusions have been designated HEB. A recloned HEB cybrid (HEB7A) has also been enucleated and fused to hypoxanthine phosphoribosyl transferase (HPRT)-deficient HeLa cells (S3AG1) and HPRT-deficient lymphocytes (WAL-2A). Cybrids were selected in thioguanine and CAP. In the fusion of enucleated (en) HEB7A to S3AG1, 1,200 colonies/10(6) parents were observed. Fusion of enHEB7A to WAL-2A was done in mass culture and cybrids were obtained on three separate occasions. In every case the parental controls were negative. All isolates tested from the above fusions have the CAP-resistant characteristics, in vivo and in vitro, of the enucleated parent and the nuclear characteristics of the CAP-sensitive parent, such as chromosome number, morphology, and specific isozyme and chromosome markers. Therefore, it can be concluded that CAP resistance is coded in the cytoplasm and not in the nucleus of 296-1 cells. Furthermore, this resistance can be transferred to cells of widely different origin and differentiated state. These studies represent the first genetic evidence of cytoplasmic inheritance in human cells.

Cell Division↗