Possibility of depression as a side effect of methyldopa.
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Aged↗
Biomedical subjects
P Tchen
Publications and source records attributed to P Tchen.
Nonradioactive labeling of synthetic oligonucleotide probes with terminal deoxynucleotidyl transferase.
Synthetic oligonucleotides were tailed at the 3' end using terminal deoxynucleotidyl transferase. Nucleotide triphosphates with free primary amines at the end of side chains were compared for their tailing efficiency and/or detection sensitivity, using biotin-11-dUTP as a reference. Free primary amines were tagged with activated biotin or fluorescein isothiocyanate. The probes were then detected with either streptavidin-alkaline phosphatase complex or anti-fluorescein antibodies and alkaline phosphatase-conjugated secondary antibodies. Tailing conditions were optimized and the probes were tested for detection of Escherichia coli ST1a enterotoxin DNA and rotavirus RNA.
Affinity Labels↗
Time-resolved fluorometry: a sensitive method to quantify DNA-hybrids.
Europium and other lanthanides can be excitated with UV-radiation, whereafter the energy is released as fluorescence, delayed in time up to 1 ms after the excitation. Eu can be used as a sensitive label in biological assays. Here we report on the application of time-resolved fluorometry to detect nucleic acid hybrids. The probe DNA was tagged with a hapten, either a fluorene or a sulfone group. After hybridization the probe DNA was detected by a two-step immunological assay with the second antibody labelled with Eu. The method is quantitative with a detection limit of 0.3 pg of actual target regions of immobilized adenovirus genomic DNA. The label was also used in sandwich hybridization, which allowed analyzing nasopharyngeal mucus for the presence of adenovirus.
2-Acetylaminofluorene↗
In situ hybridization of an acetylaminofluorene-modified probe recognized by Z-DNA antibodies in vitro.
An in situ hybridization procedure, based on the chemical modification of DNA by acetylaminofluorene (AAF), followed by a specific immunoreaction was used to localize a Z-DNA sequence isolated from the satellite DNA of Cebus appella. The AAF probe is localized on the R-band-positive heterochromatic segments of Cebus chromosomes, which strongly react with Z-DNA antibodies. The use of a nonradioactive single-stranded labeled probe confirms the reliability and the rapidity of immunochemical methods for the detection of DNA sequences on chromosomes.
2-Acetylaminofluorene↗
Hybridization on squashed flies: a method to detect gene sequences in individual Drosophila.
Specific gene sequences can be detected by DNA hybridization to individual Drosophila squashed on cellulose or nylon filters. This "squash-blot" method permits the rapid survey of DNA polymorphism in large Drosophila population samples. It could also be useful for studying chromosome aberrations, departure from diploidy, and detection of pathogenic agents in vector insects.
Animals↗
P-element distribution in Eurasian populations of Drosophila melanogaster: A genetic and molecular analysis.
Genetic and molecular investigations were carried out with Eurasian Drosophila melanogaster populations on the P-M system of hybrid dysgenesis. In 27 strains sampled from France to Middle Asia, a clear gradient exists between Western Europe, in which most modern strains are of the Q type, and eastern areas, in which M-cytotype strains predominate. Molecular analysis on individual flies was performed with two complementary probes of the cloned 2.9-kilobase P element. The results provide evidence for a gradually decreasing frequency of P elements from west to east, but the presence of P-homologous sequences has been ascertained in all of the wild M-cytotype populations analyzed. Moreover, some active P elements with GD sterility potential were revealed in the majority of M-cytotype populations when tested with a highly sensitive reference line. The gradual change in distribution of the polymorphic P family in Eurasia is discussed in relation to the structure of the elements together with the theories of P-M evolution and is interpreted as the present invasion of Eurasian populations by these elements.
Journal Article↗
DNA probe specific for Legionella pneumophila.
A procedure for preparing a DNA probe to be used in the specific detection of Legionella pneumophila by dot or colony hybridization has been devised. When total DNA from L. pneumophila was used as a radioactive probe, cross-hybridization occurred with DNA from many other species belonging to various families (including Legionellaceae, Enterobacteriaceae, Pseudomonadaceae, and Vibrionaceae). Cross-hybridizing restriction fragments in L. pneumophila ATCC 33152 DNA were identified on Southern blots. When unlabeled DNA from strain ATCC 33152 was cleaved by endonuclease BamHI, the DNA fragments cross-hybridizing with the labeled DNA from all of the other species and genera tested (or with Escherichia coli 16 + 23 S RNA) had a size of 21.4 and 16.2 kilobase pairs (major bands) and 28.0, 12.8, and 10.1 kilobase pairs (minor bands). BamHI restriction fragments of L. pneumophila DNA deprived of the cross-hybridizing fragments were pooled and used as a probe for the detection of L. pneumophila. This probe proved to be specific for L. pneumophila in colony and dot hybridization. It can potentially be used for the detection of L. pneumophila in clinical and water samples. The procedure described can be readily applied to the preparation of probes specific for phylogenetically isolated bacterial species other than L. pneumophila.
Base Sequence↗
Chemically modified nucleic acids as immunodetectable probes in hybridization experiments.
Guanine residues in nucleic acids can be modified by treatment with N-acetoxy-N-2-acetylaminofluorene and its 7-iodo derivative in an in vitro nonenzymatic reaction. The modified nucleic acids (ribo or deoxyribo, single or double stranded) are recognized by specific antibodies. They can be immunoprecipitated or used as probes in hybridization experiments and detected by immunochemical techniques.
Acetoxyacetylaminofluorene↗
Synthesis of 8-(2-4 dinitrophenyl 2-6 aminohexyl) amino-adenosine 5' triphosphate: biological properties and potential uses.
We have synthetised 8-(2-4 dinitrophenyl 2-6 aminohexyl) amino-adenosine 5' triphosphate (in short : rATP-DNP), a derivative of ATP which carries a dinitrophenyl group. We show that rATP-DNP is a substrate for calf thymus deoxynucleotidyl terminal transferase (EC 2.7.7.31) and E. coli DNA polymerase I (Kornberg polymerase EC 2.7.7.7.). It can therefore be incorporated into DNA molecules by elongation from 3' ends or by nick translation. The incorporated dinitrophenyl group can be recognized by specific antibodies which can then be detected by anti-antibodies coupled to an enzyme. DNP groups could also be introduced into DNA after enzymatic incorporation of 8-aminohexyl adenosine 5' triphosphate and reaction with 1-fluoro-2-4-dinitrobenzene. Thus, DNA molecules carrying DNP groups can ultimately be revealed by enzymatic coloured reactions. Potential uses of this enzymatic labelling as a substitute to the radioactive detection of nucleic acids, are discussed.
Adenosine Triphosphate↗
Quantitative variations of red-cell cytochrome b5 reductase (NADH-methemoglobin-reductase) in the Algerian population: evidence for defective alleles.
A striking proportion of Algerian subjects was reported among patients with congenital recessive methemoglobinemia due to cytochrome b5 reductase deficiency (Kaplan et al. 1979). A population survey was carried out in red blood cells from 1000 Algerian subjects. In 16 subjects, the cytochrome b2 reductase activity was diminished by 50%. Family studies indicated the presence of a defective allele with an overall gene frequency of 0.008. Immunologically cross-reacting material was found in red cells with low cytochrome b5 reductase activity. Leukocytes exhibited normal levels of enzyme in some families and low levels in others suggesting that at least two different deficient alleles at the DIA1 locus were present in the Algerian population. A higher prevalence of the deficient allele(s) was found in subjects of Kabyle origin.
Algeria↗
Blood group antigens in the Emerillon, Wayampi, and Wayana Amerindians of French Guiana.
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Blood Group Antigens↗
Is there a PGM1 4 allele specific to Amerindian populations?
Rare PGM1 variants in Macushi and Wayampi Amerindian populations have been compared electrophoretically and by means of electrofocusing. They appear to be identical. The findings are discussed.
Alleles↗
A genetic study of two French Guiana Amerindian populations. I. Serum proteins and red cell enzymes.
Phenotypes and gene frequencies are presented for 20 serum and erythrocyte proteins in two Amerindian populations of inner French Guiana. No genetic variability was detected in 12 of these systems. Heterozygosity was calculated for the others and the reasons for its variation are discussed.
Blood Group Antigens↗
A genetic study of two French Guiana Amerindian populations. II. Rare electrophoretic variants.
Two Amerindian populations of French Guiana were investigated for plasma proteins and red-cell enzymes. In the Wayampi tribe, rare variants were identified in 4 systems. The corresponding alleles are designated AK1 3 Wayampi, PGM1 (4/10) Wayampi, PGM2 6 Wayampi, and TfD. In the Emerillon tribe, a variant allele of PGM2, designated PGM2 6 Emerillon, was identified. For three of the systems, PGM1, PGM2, Tf, similar isozymes have been described in other Amerindian populations. These findings suggest that the corresponding alleles may have the same origin.
Adenylate Kinase↗
Homozygosity of adenylate kinase allele 3: two cases.
The phenotype AK 3.3 in the isoenzyme system of human adenylate kinase has been found in two members of the Wayampi population of French Guiana.
Adenylate Kinase↗
[Rare electrophoretic variants of the proteins adenylate kinase 1, phosphoglucomutase 1 and 2, and transferrin (AK1, PGM1, PGM2, Tf) in two populations of French Guiana].
Two small populations of inner French Guiana were investigated for red cell enzymes and serum proteins. Rare variants were found in four systems (AK1, PGM1, PGM2, Tf). Similarities between some of these variants and those found in other Amerindian populations indicate that these genetic markers may be valuable in studies of Amerindians. A mutation rate has been estimated from the results.
Adenylate Kinase↗
Histocompatibility antigens in two American Indian tribes of French Guiana.
Two South American Indian populations were typed for HLA antigens. In each, the individuals typed were related and their genealogies were known. Determination of their genotypes was done; there seemed to be neither excess nor deficiency in homozygotes. The antigens observed, A2, A9, Aw19.2 (Aw30-Aw31), A28 for the first locus and B5, Bw15, Bw35, Bw40 for the second locus are in accordance with those previously described for other South American Indians. The two populations belong to the same primary linguistic family Tupi-Guarani and they live in the same geographic area, but there was no intertribal marriage until recently. Genetic drift can explain the differences observed.
French Guiana↗
Inbreeding in recessive diseases.
The consanguinity of parents (born in France) of individuals who have a recessive disease has been studied. The frequency of first cousin marriages is less than 0.2% in the general French population. Among the parents of affected individuals the following frequencies of first cousin matings were observed: cystic fibrosis: 1.4% cystinosis: 7.1% nephronophtisis: 5.6% spinal muscular atrophy: 4.5% albinism: 5.0% achromatopsia: 12.5% (Albinism and spinal muscular atrophy are heterogeneous conditions). The increase in the frequency of first cousin marriage relative to that of the general population is much greater, as expected, in cystinosis, which is a rare disease, than in cystic fibrosis, which is the most frequent recessive disorder in France. Inbreeding in cystinosis and cystic fibrosis was also studied by computing the distance between parental birth places. This distance is smaller in cystinosis than in cystic fibrosis.
Albinism↗