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Biomedical subjects

D F Callen

Publications and source records attributed to D F Callen.

At least 181 records · Page 10Linked to original sources
PubMed1987

Mapping the human alpha globin gene complex to 16p13.2----pter.

The regional localisation of the alpha globin (HBA) complex on the short arm of chromosome 16 was investigated by in situ hybridisation, Southern blot analysis, and linkage analysis using the fragile site at 16p12.3 (FRA16A) and translocation breakpoints within band 16p13.1. HBA was found to be distal to the two translocation breakpoints within band 16p13.1 and not closely linked to FRA16A. In situ hybridisation to the distal portion of the fragment on metaphase chromosomes expressing the fragile site and the observation of considerable recombination between FRA16A and HBA supports a localisation for HBA closer to the telomere than to FRA16A, at 16p13.2----pter.

Chromosome Mapping↗
PubMed1987

Molecular genetics of human chromosome 16.

The major diseases mapped to chromosome 16 are adult polycystic kidney disease and those resulting from mutations in the alpha globin complex. There are at least six other less important genetic diseases which map to this chromosome. The adenine phosphoribosyltransferase gene allows for selection of chromosome 16 in somatic cell hybrids and a hybrid panel is available which segments the chromosome into six regions to facilitate gene mapping. Genes which have been mapped to this chromosome or which have had their location redefined since HGM8 include APRT, TAT, MT, HBA, PKD1, CTRB, PGP, HAGH, HP, PKCB, and at least 19 cloned DNA sequences. There are RFLPs at 13 loci which have been regionally mapped and can be used for linkage studies.

Adenine Phosphoribosyltransferase↗
PubMed1987

Chromosomal analysis in Ewing sarcoma.

Two cases of Ewing sarcoma were karyotyped by using a fluorodeoxyuridine synchronisation procedure on short term cultures of fresh tumour material. This procedure enables rapid cytogenetic analysis of such material. Both showed relatively simple karyotypes, 48,XX, +2, +7,t(11;22)(q24;q12), ?dup(12)(q21----q24) and 47,XX,i(1q),t(11;22)(q24;q12). These results further support this translocation between chromosomes 11 and 22 as a specific marker for Ewing sarcoma. Cytogenetic studies in such cases are an important adjunct to histological studies and in some cases may contribute to the resolution of the diagnosis.

Adolescent↗
PubMed1986

New regional localisations for HAGH and PGP on human chromosome 16.

The chromosomal locations for the electrophoretic markers hydroxyacyl glutathione hydrolase (HAGH) and phosphoglycolate phosphatase (PGP) were examined using a human-mouse hybrid panel of chromosome 16. The assignment for HAGH was confirmed to chromosome 16 using a cell line with chromosome 16 as the only human chromosome. Both HAGH and PGP were present only in cell lines containing human 16p13. This localisation for PGP indirectly places the tightly linked genes for the alpha-globin cluster and adult polycystic kidney disease on 16p13.

Animals↗
PubMed1986

A new location for the human adenine phosphoribosyltransferase gene (APRT) distal to the haptoglobin (HP) and fra(16)(q23)(FRA16D) loci.

The human adenine phosphoribosyltransferase gene (APRT) was mapped with respect to the haptoglobin gene (HP) and the fragile site at 16q23.2 (FRA16D). A subclone of APRT and a cDNA clone of HP were used for molecular hybridization to DNA from mouse-human hybrid cell lines containing specific chromosome 16 translocations. The APRT subclone was used for in situ hybridization to chromosomes expressing FRA16D. APRT was found to be distal to HP and FRA16D and was localized at 16q24, making the gene order cen-FRA16B-HP-FRA16D-APRT-qter.

Adenine Phosphoribosyltransferase↗
PubMed1986

A mouse-human hybrid cell panel for mapping human chromosome 16.

A mouse-human hybrid cell panel for human chromosome 16 was constructed from human cell lines with breakpoints on chromosome 16 at p13.11, q13, q22 and q24. Fusions with the human fibroblast line GM3884, t(X;16)(q26;q24) allowed the isolation of clones with either the derivative X or the derivative 16 as the only human chromosome. This was a consequence of both the genes APRT and HPRT being involved in the translocation. The breakpoints of the line GM3884 were confirmed by aphidicolin induction of the common fragile site at 16q23. The results of the fusions with this line suggest a localisation of the APRT gene at 16q24 and confirm the localisation of HPRT to Xq26 to Xq27.3. These hybrid cell lines enable the localisation of genes and DNA fragments to six clearly defined regions. Further localisation within three of these regions is possible by use of the three fragile sites on chromosome 16. In situ hybridisation with the probe pBLUR confirmed that of three lines tested all contained a single human chromosome.

Animals↗
PubMed1985

A complex translocation in acute promyelocytic leukemia.

The breakpoints of a complex three-way translocation involving chromosomes X, #15, and #17 were resolved in a case of acute promyelocytic leukemia (APL). It is now apparent that similar cases of variant chromosome translocations are found in both chronic granulocytic leukemia (CGL) and APL. The morphological and clinical findings in this case emphasize the variability found in some cases of APL.

Chromosomes, Human, 13-15↗
PubMed1985

Paracentric inversions in man.

Two new cases of familial paracentric inversions, 46,XY,inv(3)(p21.1p25) and 46,XY,inv(7) (q22.3q36.1) are presented. A review of published cases suggests that prenatal diagnosis for carriers of paracentric inversions is not warranted. However, care must be exercised in eliminating the possibility of insertions.

Abnormalities, Multiple↗
PubMed1983

Interactions between C-bands of chromosomes 1 and 9 in recurrent reproductive loss.

The size of the heterochromatic regions of chromosomes 1 and 16 was measured in a Test group of women with histories of recurrent spontaneous abortion and a Control group of fertile women. Measurements were made on Giemsa banded preparations and the euchromatic regions of 1q and 16q were used to correct for between-cell contraction. For each chromosome pair, the larger and smaller chromosome was identified and populations of each were compared between the two subject groups. For chromosome 1, the smaller chromosome of the Test group was significantly smaller than that of the Control group (P less than 0.001) and the size of the pair difference was larger in the Test than in the Control group (P less than 0.01). For chromosome 16, the smaller chromosome of the Test group was smaller than that of the Control group (5% level). The interaction of chromosome 1 and chromosome 9 heterochromatin in each individual has been analyzed. The combined score for the smaller chromosome 1 and the larger chromosome 9 shows a bimodal distribution and allows discrimination between the two subject groups. Various possible ways in which this interaction might affect reproductive outcome are discussed.

Abortion, Habitual↗
PubMed1983

Chromosome abnormalities in chronic lymphocytic leukemia revealed by TPA as a mitogen.

Bone marrow and peripheral blood cultures of chronic lymphocytic leukemia patients were mitogenically stimulated with TPA (12-O-tetradecanylphorbol-13-acetate). Clonal cytogenetic abnormalities were detected in frequencies varying from 15% to 100%, in five of the six patients studied. Parallel studies with pokeweek mitogen showed a much lower level of stimulation and only two abnormal clones were detected. The chromosome abnormalities described in this study are similar to those reported in CLL by other authors, particularly with respect to trisomy 12 and deletion 11q. A significant frequency of hypodiploidy and chromosome deletion was also detected in this study, and further studies are underway to determine the significance of these findings.

Adult↗
PubMed1982

Within pair differences of human chromosome 9 C-bands associated with reproductive loss.

The size and position of the heterochromatic regions of chromosome 9 were examined in a group of women with histories of recurrent miscarriage and a control group of fertile women. Measurements were made on whole chromosomes (variability between chromosomes was taken to reflect differences in heterochromatin), and corrections for between-cell contraction were made by comparison with chromosome 7. Chromosomes were analysed in pairs and the following results were obtained: (1) The larger of the pairs of chromosomes of the test group were significantly larger than those of the control group: (2) The smaller of the pairs of chromosomes were the same in each group: (3) The differences between the chromosome pairs were significantly greater in the test than the control group: and (4) The sums of the homologous chromosomes were significantly greater in the test than in the control group. Independent assessment also showed that a significantly higher frequency of complete pericentric inversions of chromosome 9 was present in the test than the control group. These results are discussed in the light of two hypotheses: (1) The difference in the size of the homologous chromosomes is critical, and (2) the total heterochromatic content of a chromosome and/or cell is critical. Some evidence is presented to support each hypothesis, but the former is the more favoured by the data.

Centromere↗
PubMed1981

Mutagenesis at the ad-3A and ad-3B loci in haploid UV-sensitive strains of Neurospora crassa. V. Comparison of dose--response curves of single- and double-mutant strains with wild-type.

The interactions of mutant alleles that individually confer radiation sensitivity in Neurospora crassa are being studied with regard to their effects on radiation-induced inactivation and forward-mutation induction at the ad-3 loci. This paper reports attempts to construct 3 double-mutant strains containing the following pair-wise combinations of repair-deficient mutants: upr-1,uvs-2; uvs-2,uvs-6; and uvs-3,uvs-6. The double-mutant strain with the 2 excision-repair-deficient mutants upr-1 and uvs-2 shows increased sensitivity to X-ray-induced mutagenesis and inactivation, relative to that shown by either of the parental single-mutant strains. This double mutant is no more sensitive than the parental single-mutant strains to either UV mutagenesis or inactivation. The combination of the uvs-2 and uvs-6 double-mutant strain is considerably more sensitive to both UV and X-ray inactivation than either the uvs-2 or uvs-6 strain, but it shows no greater sensitivity than the parental strains to ad-3 mutation induction by either agent. The combination of the uvs-3 and uvs-6 alleles is inviable. Tetrad analysis and microscopical examination of ascospores shows that ascospores of presumptive genotype uvs-3, uvs-6 do not grow beyond the formation of a few hyphal threads. The lethal and mutagenic effects of UV and X-irradiation in these double-mutant strains are interpreted in terms of the repair systems in Neurospora and other microorganisms.

DNA Repair↗
PubMed1980

Cytochrome P-450 mediated genetic activity and cytotoxicity of seven halogenated aliphatic hydrocarbons in Saccharomyces cerevisiae.

Cells of Saccharomyces cerevisiae, harvested from log-phase cultures, contain cytochrome P-450 and are capable of metabolizing promutagens to genetically active products. The activities of 7 halogenated aliphatic hydrocarbons in the yeast system have been investigated. All of the compounds tested (methylene chloride, halothane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene and s-tetrachloroethane) induced mitotic gene convertants and recombinants and, to a lesser extent, gene revertants when incubated with log-phase cells of the yeast strain D7. An examination of the difference spectra observed upon the addition of carbon tetrachloride, halothane and trichloroethylene to whole-cell or microsomal suspensions of yeast suggested that cytochrome P-450 mediated the metabolism of the hydrocarbons tested to cytotoxic and genetically active compounds.

Biotransformation↗
PubMed1978

Effects of the epoxide hydrase inhibitor, 1,1,1-trichloropropane-2,3-oxide on the genetic activity of aflatoxin B1 metabolites in in vitro activation test systems.

The epoxide hydrase inhibitor 1,1,1-trichloroprophane-2,3-oxide (TCPO) was genetically active to cells of S. cerevisiae and conidia of N. crassa. This genetic activity could be eliminated or reduced to near spontaneous levels in the presence of the S-9 fraction of hamster liver homogenate. The addition of TCPO to an in vitro activation system containing aflatoxin B1 resulted in an increase in the genetic activity of aflatoxin B1, and this increase was dependent on the dose of TCPO. These results are discussed in relation to the possible metabolism of the promutagen aflatoxin B1.

Aflatoxins↗