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Biomedical subjects

D Klein

Publications and source records attributed to D Klein.

At least 217 records · Page 12Linked to original sources
PubMed1982

Patient characteristics that elicit negative responses from family physicians.

Responding anonymously to a questionnaire asking them to list medical conditions and social characteristics of patients that evoked negative responses, 439 family physicians specified 1,846 medical conditions and 1,519 social characteristics. Of the medical conditions, the largest category (60 percent) represented conditions for which medical treatment offered little or no likelihood of cure or alleviation. Of the social characteristics, the largest category (33 percent) involved behavior that violated the physician's personal norms, even through it had little or no bearing on the patient's health. It appears that the responses accurately reflect the Protestant Ethic value system characteristics of Western Europe and the United States, but this constellation of values is accentuated in physicians by their selection and their professional training. Although negative responses to patient characteristics do not inevitably lead to inferior treatment of the negatively perceived patient, negative feelings might be reduced through changes in both the undergraduate and graduate levels of medical education.

Attitude of Health Personnel↗
PubMed1982

Evidence for placing the Neu-1 locus within the mouse H-2 complex.

Congenic lines B10.KPA42, B10.KPA132, B10.SNA57, B10.DRB62, and B10.WOA105 carry H-2 haplotypes of wild mice on the genetic background of the strain C57BL/10Sn. Two of the lines (B10.DRB62 and B10.WOA105) have H-2 haplotypes indistinguishable from H-2v of B10.SM. The H-2 haplotype of one line (B10.SNA57) seems to have arisen from H-2v by recombination between the D and Qa-2 loci. The H-2 haplotypes of the remaining two lines probably arose from H-2v by recombination between the C4 and D loci. Since all six and no other lines carry the rare Neu-1a allele, the neuraminidase-1 locus is probably located proximal to the H-2D locus. Typing of H-2s recombinants for the enzyme acid phosphatase liver, the processing of which is controlled by the Neu-1 locus, suggests that the locus resides between the E alpha and D loci, that is in the S region.

Acid Phosphatase↗
PubMed1981

Interaction between non-classical beta-lactam compounds and the Zn2+-containing G and serine R61 and R39 D-alanyl-D-alanine peptidases.

Streptomyces albus G secretes a Zn2+-containing D-alanyl-D-alanine peptidase. Streptomyces R61 and Actinomadura R39 secrete D-alanyl-D-alanine-cleaving serine peptidases. The effect of non-classical beta-lactam antibiotics on these three model enzymes has been studied. Mecillinam, cefoxitin, quinacillin, quinacillin sulphone, clavulanate and N-formimidoylthienamycin have no effect on the Zn2+-containing enzyme. 6-Amino-penicillanic acid slowly inactivates this enzyme and 7-aminocephalosporanic acid behaves as a reversible inhibitor. Cefoxitin and N-formimidoylthienamycin are potent anti-bacterial agents; they effectively inactivate the serine R39 enzyme and, to a lesser extent, the serine R61 enzyme. All the other beta-lactam compounds tested, including mecillinam, are slow inactivators of these serine enzymes. The intermediates formed between 6-aminopenicillanic acid and the R61 and R39 enzymes are long- and short-lived respectively, whereas those formed between 7-aminocephalosporanic acid and the same R61 and R39 enzymes are short- and long-lived respectively. Breakdown of the short-lived intermediates thus obtained gives rise to several ninhydrin-positive degradation products. The intermediates formed between clavulanate and the serine enzymes are long-lived. With the R39 enzyme, the inactivated complex formed in a first step undergoes subsequent monomolecular rearrangement to give rise to a second species exhibiting a high absorbance at 273 nm.

Actinomycetaceae↗
PubMed1981

The exocellular beta-lactamase of Streptomyces albus G. Purification, properties and comparison with the exocellular DD-carboxypeptidase.

The exocellular beta-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30 000-31 000, has a rather low isoelectric point (at pH 6.0) and contains less lysine (2.1%) and more half-cystine residues than most beta-lactamases from other Gram-positive bacteria. Penicillins are much better substrates than delta 3-cephalosporins; the catalytic-centre activity of good penicillin substrates is 333-500 s-1. The exocellular, mol.wt. 17 000 DD-carboxypeptidase of S. albus G [previously purified to protein homogeneity; Duez, Frère, Geurts, Ghuysen, Dierickx & Delcambe (1978) Biochem. J. 175, 793-800] behaves as an exceedingly poor beta-lactamase, hydrolysing benzylpenicillin into benzylpenicilloate 5 x 10(-6)-fold less rapidly than does the exocellular beta-lactamase. To all appearances, the beta-lactamase has no bivalent cation requirement whereas, as shown elsewhere [Dideberg, Charlier, Dupont, Vermeire, Frère & Ghuysen (1980) FEBS Lett. 117, 212-214, and Dideberg, Joris, Frère, Ghuysen, Weber, Robaye, Delbrouck & Roelands (1980) FEBS Lett. 117, 215-218], the DD-carboxypeptidase possesses one essential Zn2+ ion per molecule. Peptide 'mapping' and immunological studies suggest that the two Streptomyces enzymes probably have very different structural and mechanistic properties.

Amino Acids↗
PubMed1980

Material-specific perceptual interference for visual words and faces: implications for models of capacity limitations, attention, and laterality.

Four experiments were conducted to test the hypothesis that perceptual interference effects would be greatest among items that are processed by the same hemisphere than among items processed by different hemispheres. Recognition of two peripheral faces, flanked on either side of a central item that also had to be identified, was worse when the item was a face than when the item was a word. The opposite results were obtained for peripheral word identification by naming (Experiment 1). Identical results were obtained when a nonsense form was substituted for the central face (Experiment 2). Since unfamiliar faces and nonsense forms are processed primarily by the right hemisphere and words are processed by the left, the results are consistent with the hypothesis. The interference effect was the same even when the central nonsense shape was identified by naming, suggesting that the locus of the effect is not at response selection (Experiment 3). Ignoring the central item only reduces the interference effects but does not eliminate it (Experiment 4). Although in general words were perceived better in the right visual field, and faces were perceived better in the left, small fluctuations in the magnitude but not in the direction of perceptual asymmetries were sometimes noted with changes in the central item. The fluctuations were usually opposite to those predicted by attentional models of perceptual asymmetries.

Attention↗
PubMed1980

[Dominant chorioretinal dystrophy].

Provisional discussion about a family tree of a large family (13 members of one generation) presenting with a strange dominant hereditary chorioretinal degeneration, probably of Sorsby's type.

Adult↗
PubMed1980

[Heredoataxia, tapetoretinal degeneration and dysmorphosis in a boy aged 16 (author's transl)].

The authors describe a boy aged 16 presenting with a heredoataxia of Friedreichs type which began when the patient was eight and which was accompanied by a diffuse degeneration of the posterior pole of the retina developing at the same time. This syndrome is attended by dysmorphoses (slight craniofacial dysostosis and other developmental anomalies), retarded growth (height: 1 m. 36) and retardation of puberty. The authors advance the hypothesis that a recessive pleiotropic gene is responsible for both the neuroretinal syndrome and the dysmorphosis and quote the literature referring to this problem.

Abnormalities, Multiple↗
PubMed1980

Enzymatic method for rapid and sensitive determination of beta-lactam antibiotics.

A rapid and sensitive procedure for the estimation of beta-lactam antibiotics is described which makes use of the ability of these antibiotics to inactivate the R39 DD-carboxypeptidase. Depending on the values of the kinetic parameters which govern the reaction, the antibiotics fall into two groups. The lower limit for the quantitative estimation of the antibiotics of groups I and II is about 5 and 50 pmol/ml, respectively. The procedure has been adopted to biological fluids such as human sera and cows' milk.

Animals↗
PubMed1980

[The detection of beta-thalassemia minor (author's transl)].

A statistical analysis was done on the levels of Hb A2 and Hb F in 1 340 normal subjects and 356 subjects heterozygous for beta-thalassemia. This study revealed that both groups had a normal distribution of Hb A2 and a gaussologarithmic distribution of Hb F. The plotted curves show an overlapping zone between the two populations. This area lies between 3.0% and 3.5% Hb A2 and between 0.2% and 1.0% Hb F. More than 97% of the heterozygotes for beta-thalassemia have a Hb A2 level situated outside the overlapping region, which permits diagnosis. Of the remaining 3%, only the "silent carriers" do not manifest the usual hematological characteristics of beta-thalassemia minor (hypochromia, microcytosis, diminished osmotic fragility, and erythrocytes with basophilic stippling). To diagnose this group it is necessary to determine globulin chain synthesis. This test is reserved for those subjects considered as "high risks."

Ethnicity↗
PubMed1980

[Formation of nitrosamines in cheese products].

Several strains of micromycetes used as fermentation agents in the cheese industry or having led to accidents during cheese making are able to favor the formation of nitrosamines in 60% of the cases. The concentrations observed are similar to those found by other authors with other microorganisms. The results obtained in a semi-synthetic medium are checked during the ripening of experimental camembert type cheese made from milk containing nitrates and cultured with a strain of Penicillium camemberti, which favors very much the synthesis of nitrosamines. The amount of nitrosodimethylamine formed in this cheese increases from 5 to 20 ppb during ripening. A tentative explanation of the mechanism of formation is outlined.

Cheese↗
PubMed1980

[Salivary and biliary excretion of nitrates in the dog].

The salivary and biliary excretion of nitrates has been studied in dogs. We have administered intravenously [15N] sodium nitrate (51% enrichment) and we have studied its fate in blood, bile and saliva by estimation of NO3-, NO2- and 15N at the time of 0, 30 mn, 1 h and 3 h. This experimentation, made on 9 dogs, indicates a total absence from nitrites in blood, bile and saliva and confirms the existence of biliary excretion of nitrates. Last, the evolution of 15NO3 rates, measured by mass spectrography, indicates that salivary glands produce an important endogenous accumulation of nitrate ion.

Animals↗