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Biomedical subjects

B Haas

Publications and source records attributed to B Haas.

119 records · Page 7Linked to original sources
PubMed1981

Specifically primed synthesis in vitro of full-length DNA complementary to potato-spindle-tuber viroid.

Potato spindle tuber viroid (PSTV) RNA is transcribed in vitro by reverse transcriptase into complementary DNA in the presence of synthetic oligodeoxyribonucleotides as primers. In the case of priming with the pentadecadeoxyribonucleotide d(T-T-C-T-T-T-T-T-T-C-T-T-T-T-C) complementary to PSTV RNA from nucleotides 49 to 63, specificity of transcription initiation allows rapid sequencing of part of the viroid genome using chain-terminating dideoxyribonucleoside triphosphates. The DNA transcripts obtained represent distinct molecular species with the largest product being a full-length copy of the viroid RNA template. Molecular hybridization with 32P-labeled complementary DNA detects sequence homologies among different viroid species.

Base Composition↗
PubMed1981

[The epidemiology of asthma in Lorraine. A method of Study (author's transl)].

The authors undertook an epidemiological study to held useful criteria to identify asthma sufferers. A simple questionnaire was used asking three questions: - Do you wheeze on breathing? - Do you have attacks of breathlessness during the night? - Do you have asthma? 7,904 people were questioned at the Centre for Preventive Medicine at Vandoeuvre-les-Nancy over a year and 1,062 gave a positive response to at least one question. The replies were sub-divided into 5 groups according to the pattern of response and were then given a further clinical assessment as follows: - A sensitivity test for house dust allergy; - A bronchial sensitivity test to Acetylcholine; - The level of blood eosinophilia; - Presence or absence of a family history of asthma. The results were then compared to a matched group of controls who gave a negative reply to all three questions. The authors concluded that the term asthma should only be used by people who recognize themselves as asthmatics and can identify at least one trigger factor in their symptoms. One frequently finds in such people : a family history of asthma, a positive allergy test to the house dust mite, and eosinophilia. On the other hand those with only one or two symptoms (dyspnoea or wheezing) without recognizing themselves as asthmatics had little evidence of a family history of asthma, a sensitivity to the house dust mite comparable to controls and no eosinophilia; in these people there was a striking relationship to tobacco consumption. The Acetylcholine test shows little discriminative value in an epidemiological study of this nature; asthmatics could not be separated from patients with chronic air-flow obstruction, particularly when due to tobacco. It would be helpful to find a test of bronchial hyperactivity which could be used epidemiology. As a result of this study it is possibly to place the prevalence of asthma in the South of Lorraine in the range of 1.7 to 3.6% of the population.

Acetylcholine↗
PubMed1980

Prenatal diagnosis of Lesch-Nyhan syndrome and some characteristics of hypoxanthine-guanine phosphoribosyltransferase and adenine phosphoribosyltransferase in human tissues and cultivated cells.

Activities of phosphoribosyltransferase for hypoxanthine and adenine were investigated in erythrocytes and human tissues of fetuses and adults as well as in cultivated fibroblasts and amniotic fluid cells. Kinetic characteristics of these enzymes were also studied in patients with the Lesch-Nyhan syndrome and with partial deficiency for hypoxanthine phosphoribosyltransferase (HGPRTase), and their obligate heterozygotes. The affinity of HGPRTase for both substrates in partial deficiency decreased to 13 to 20% of normal and by a less degree in its heterozygotes (50 to 65% of normal). A slight decrease in the Km for phosphoribosylpyrophosphate was observed in the case of heterozygotes for the Lesch-Nyhan syndrome. Elevated erythrocytic adenine phosphoribosyltransferase (APRTase) activity was found in fetuses, patients with the Lesch-Nyhan syndrome or with partial deficiency, and in some heterozygotes as well. However, the Km of APRTase for hypoxanthine in these subjects was the same as that in the normal adults. The HGPRTase activity in liver increased almost 4 times during the developmental period, whereas the APRTase activity remained approximately the same. In fetal liver, the APRTase activity was almost two times higher than the HGPRTase activity, whereas in fetal brain the HGPRTase activity was higher. The Km of HGPRTase for hypoxanthine in cultivated cells and human tissues were similar to that in erythrocytes and leukocytes. On the other hand, the HGPRTase affinity for phosphoribosylpyrophosphate in these cells was cconsiderably larger than in erythrocytes or in leukocytes.

Adenine Phosphoribosyltransferase↗
PubMed1980

Characterization of a phosphoglycerate kinase deficiency variants not associated with hemolytic anemia.

The properties of a variant phosphoglycerate kinase (PGK) found in a large German clan were examined. The normal and variant enzymes, isolated by affinity chromatography, have the same molecular weight, specific activity, substrate affinity, and nearly identical pH-optima. Using immunoinactivation and immunodiffusion, the same specific activity for both forms was again determined. Since the enzymatic activity in older and younger erythrocytes varied only slightly, and since the specific activity of the variant was normal, the variant seems to be stable in vivo. This suggests that the decreased enzyme content is due to a decreased synthesis rate. The variant PGK described here is distinctly different from the known PGK variants and has been designated as "PGK München."

Anemia, Hemolytic↗
PubMed1980

Non-stepwise methods in the preparation of building blocks for polynucleotide synthesis.

Oligonucleotide fragments of the general sequence ABn, BnC and ABnC as building units for polynucleotide synthesis can be obtained by three types of reactions, namely the sequence-specific co-condensation of nucleic acid constituents, the sequence-specific degradation of copolymers and the limited addition of nucleotides to primers. Examples for these reactions are described and the scope and application of the approach discussed.

Base Sequence↗
PubMed1979

Characteristics of galactokinase and galactose-1-phosphate uridyltransferase in cultivated fibroblasts and amniotic fluid cells.

The kinetic characteristics of galactose-1-phosphate uridyltransferase and galactokinase in cultivated fibroblasts and amniotic fluid cells were investigated. The Km values of galactokinase for galactose at 2.0 mM ATP are 0.34 mM in amniotic fluid cells and 0.48 mM in fibroblasts. The Km values for ATP at 0.5 mM galactose are 1.25 mM and 2.10 mM. Transferase and galactokinase activities and protein content increase logarithmically during the growth of cultivated cells. The specific activity of both enzymes also increases and reaches a maximum level 10--15 days after subculture. The specific activity of transferase increases faster than that of galactokinase in the case of amniotic fluid cells. In the case of fibroblasts the specific activity of galactokinase increases faster than that of transferase.

Amniotic Fluid↗
PubMed1978

Refined mapping of the gene for glutathione reductase on human chromosome 8.

Activity of the enzyme glutathione reductase (EC 1.6.4.2) in erythrocytes and fibroblasts of a patient with karyotype 46, XY, del(8) (pter-p212:) was found to be in the normal range. With results from other laboratories, this allowed a more precise mapping of the gene for this enzyme in the region 8p2100-8p212.

Child↗
PubMed1978

[Prenatal diagnosis in pregnancies at advanced maternal age (author's transl)].

Among 113 prenatal diagnoses in pregnancies at advanced maternal age (mothers older than 37 years) 7 aberrant fetal karyotypes were found (6.2%). Detailed reports of one case of trisomy 21, 18 and 13 each, as well as of XXY-, XYY- and XXX gonosomal constitution respectively are presented in the following. The frequency and severity of chromosome aberrations occurring in fetuses from elder women are discussed with respect to data from the literature. It seems that this group bears a higher risk for chromosomally abnormal offspring than has been suggested before.

Abnormalities, Multiple↗
PubMedDate not supplied

A new liquid homogeneous assay for HDL cholesterol determination evaluated in seven laboratories in Europe and the United States.

We evaluated a new liquid homogeneous assay for the direct measurement of high density lipoprotein cholesterol (HDL-C Plus) in seven laboratories. The assay includes two reagents which can be readily used in most available clinical chemistry analyzers. The total CVs of the new method were below 4.6% and the bias in relation to the designated comparison method was below 3.9%. The total error ranged between 4 to 7%. HDL-C values determined by this method were in good agreement with those obtained by the old homogeneous assay using lyophilized reagents, and other homogeneous and precipitation assays (0.944 < r < 0.996). The assay was linear up to at least 3.89 mmol/l HDL-C. Hemoglobin did not interfere, whereas in icteric samples slight deviations were observed. Lipemia up to 11.3 to 22.6 mmol/l triglycerides did not interfere with this homogeneous HDL-C assay. In samples of patients with paraproteinemia, discrepant results were seen. This liquid homogeneous HDL-C assay was easy to handle and produced similar results in all laboratories participating in this study. This method will enable clinical laboratories to reliably measure HDL-C for risk assessment of coronary heart disease.

Artifacts↗