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Biomedical subjects

A Weber

Publications and source records attributed to A Weber.

At least 487 records · Page 27Linked to original sources
PubMed1984

Evaluation of the slide agglutination test for detection of leptospiral antibodies in serum samples of slaughter pigs.

Serum samples of 259 randomly selected slaughter pigs were studied comparatively in the microscopic agglutination test (MAT) and the slide agglutination test (SAT) for the presence of leptospiral antibodies. 12 of 13 serum samples with MAT titres of 1:400+ + and higher were positive in the SAT. 27 of 46 sera with MAT titres in the borderline range (1:100+ + to 1:400+) showed a positive reaction in the SAT. 31 of 200 serum samples with MAT titres of 1:100+ and less reacted also positively in the SAT. Statistical evaluation of the results showed that the SAT is accurate if results are positive but less so if the results are negative (sensitivity 92.3%, specificity 76.4%).

Abattoirs↗
PubMed1983

Molecular cloning of cDNA for rat L-type pyruvate kinase and aldolase B.

Two double-stranded cDNA recombinant pBR322 plasmid libraries were constructed starting from high carbohydrate diet rat liver poly(A)+ mRNA, either fractionated by denaturing sucrose gradient centrifugation for the cloning of L-type pyruvate kinase cDNA, or nonfractionated for aldolase B. Both libraries were screened with single-stranded cDNA probes reverse transcribed from fasted or high carbohydrate diet rat liver mRNAs. mRNAs from fasted animals were also fractionated by sucrose gradient centrifugation and mRNAs from the fed animals were, in addition, further purified by high performance liquid gel filtration chromatography. Those clones hybridizing with the "positive" probe (from animals fed the high carbohydrate diet) and not with the "negative" one (from fasted animals) were preselected and their plasmid DNA was purified and analyzed by positive hybridization-selection. Thirty of 4500 bacteria colonies transformed by recombinant plasmids were preselected by differential screening for pyruvate kinase, and 8 of 864 colonies for aldolase B. Twenty-two recombinant plasmids for pyruvate kinase and two for aldolase B were shown to contain specific cDNA inserts by positive hybridization-selection. Plasmids DNAs of some pyruvate kinase and aldolase B clones (whose inserts ranged from 700 to 1050 bases in length) were labeled by nick translation and used as probes for Northern blot hybridization. The pyruvate kinase cDNA probes recognized mainly a 3400-base RNA species which was detected in high carbohydrate diet rat liver, but not in fasted rat liver and in tissues which do not synthesize L-type pyruvate kinase. In addition, some pyruvate kinase probes hybridized with minor RNA species of about 2000 bases in length, only observed after carbohydrate diet. For aldolase B, the recombinant plasmid DNA hybridized with a single RNA species of 1750 bases. This RNA, detected in kidney, small intestine and liver, was induced by a high carbohydrate diet and increased with liver development. The rat probe cross-hybridized with human aldolase B messenger RNA.

Animals↗
PubMed1983

High-performance liquid chromatographic quantitation of trimethoprim, sulfamethoxazole, and N4-acetylsulfamethoxazole in body fluids.

We describe a rapid, precise and simple procedure for the quantitative determination of trimethoprim, sulfamethoxazole, and N4-acetylsulfamethoxazole in body fluids by reversed-phase high-performance liquid chromatography. This method utilizes antipyrine as an internal standard with the compounds detected by dual-wavelength monitoring at 225 nm and 254 nm after a single-step extraction. Precision, sensitivity, and accuracy of this assay are within the range of clinical utility; the coefficient of variation is less than or equal to 3%, sensitivity less than 0.5 micrograms/ml for all compounds, and recovery greater than 97%. The short time for performance and small sample size makes the assay ideal for clinical drug monitoring and pharmacokinetic studies.

Chromatography, High Pressure Liquid↗
PubMed1983

Prevention of lithocholate--induced cholestasis by cycloheximide, an inhibitor of protein synthesis.

Our previous investigations have shown that lithocholic acid (LCA)-induced cholestasis is associated with an increased synthesis of microsomal cholesterol which is transported with LCA and incorporated in the bile canalicular membrane. As the significance of these changes remains unknown the effect of interference with microsomal protein synthesis and/or with the cellular transport of cholesterol was studied. Male Wistar rats were injected i.p. with cycloheximide at the dose of 15 micrograms/100 g BW 3 times over a 24-hour period. After cannulating the common bile duct and collecting bile for one hour, the animals were either injected i.v. with 12 mumoles C14-LCA/100 g BW or with a 7.5% albumin solution and bile was collected for another hour. LCA injection in untreated animals reduced bile flow by more than 90% of control values. In contrast, bile flow in the group treated with cycloheximide and LCA was normal and did not differ from that of animals given cycloheximide alone. Bile salt secretion rate was increased in the cycloheximide-LCA group over the control groups. This was mainly due to the secretion of more than 80% of the injected LCA and was confirmed by the distribution of the radioactivity. By electron microscopy, the liver in the cycloheximide-LCA group did not show any of the well defined changes associated with LCA-induced cholestasis. These data suggest that microsomes play an important role in the pathogenesis of LCA cholestasis and that inhibition of microsomal protein synthesis can prevent its development.

Animals↗
PubMed1983

Specificity and properties of the nucleotide carrier in chromaffin granules from bovine adrenal medulla.

1. The influence of various substances on the uptake of [3H]ATP and [14C]-noradrenaline into isolated bovine chromaffin granules was investigated. The carrier-mediated [3H]ATP uptake is specifically inhibited by SO42-, PO43- and phosphoenolpyruvate. Compounds with carboxylic acid or sulphonic acid groups had no significant inhibitory effects on either uptake. 2. 35SO42-, 32PO43- and phosphoenol[14C]pyruvate are taken up into chromaffin granules by a temperature-dependent process that is inhibited by atractyloside, uncouplers of oxidative phosphorylation and lipid-permeant anions. The apparent Km of 35SO42- uptake is 0.4 mM. 3. These results indicate that the nucleotide carrier in chromaffin granules has a broad specificity, transporting compounds with two strong negative charges. 4. Amino acid probes influence the uptake of ATP and catecholamines differently. Pyridoxal phosphate inhibits both uptake processes, 4,4'-di-isothiocyanostilbene-2,2'-disulphonic acid preferentially blocks ATP uptake, whereas phenylglyoxal blocks only ATP transport. It is suggested that the nucleotide carrier possesses arginine residues in a functionally important position. 5. The significance of these results obtained on isolated granules for the function of chromaffin granules within the cell is discussed.

Adenosine Triphosphate↗
PubMed1983

An experimental study on irritation and annoyance due to passive smoking.

Forty subjects were exposed to cigarette smoke produced by a smoking machine in a climatic chamber. The degree of air pollution due to cigarette smoke corresponded to 2.5 and 1.3 ppm delta CO. The concentrations of particulate matter, NO and NO2, were measured. The effects on subjective irritation, annoyance and eye blinking rate were determined. All measured effects increased with increasing smoke concentration as well as with exposure duration. Based on these effects, a tolerable limit in the range between 1.5 and 2.0 ppm delta CO is proposed.

Carbon Monoxide↗
PubMed1983

[Concentrations of pollutants in the smoke blowing area of smokers].

The concentrations of particles and nitrogen oxide have been measured in the "blowing cloud" of a smoker. At a distance of 1 m from the smoker, the peak values range from 41 to 750 ppb NO and 3,330 to 99,680 micrograms/m3 particles. These high concentrations decrease very rapidly (half-life period between 2 and 20 s). At a distance of 3 m, there is no more real "blowing cloud". In addition to the sidestream smoke, the relatively high concentrations of particles in the "blowing cloud" of the smoker could also be responsible for the acute irritating effects of the passive smoker.

Humans↗
PubMed1983

A survey on attitudes towards passive smoking among schoolchildren and students in Switzerland.

The attitudes and reactions to passive smoking as well as the attitudes to active smoking have been investigated among schoolchildren and students in Zurich. 183 13-year-old children, 203 16-year-old children, and 367 23-year-old students were interviewed by a questionnaire. The most interesting results are as follows: -- Significantly more of the younger children (81%) than of the elder children (70%) and the students (70%) dislike passive smoking. -- Significantly more nonsmokers dislike passive smoking than smokers. -- The subjects whose parents smoke dislike passive smoking less than the subjects whose parents do not smoke. -- 80% of the students, 64% of the elder children, and 82% of the younger children complain of one or more kinds of irritations due to passive smoking. The most common impairment is eye irritation, followed by cough and nose irritation. -- More nonsmokers complain of irritations than smokers. -- There is no significant difference between girls and boys as for the reactions to passive smoking.

Adolescent↗
PubMed1983

High-pressure liquid chromatographic quantitation of azlocillin.

We describe a rapid, precise, and simple procedure for the quantitation of azlocillin in serum and in aqueous solutions by high-pressure, reverse-phase liquid chromatography. This method uses a single precipitation step, detection by dual-wavelength monitoring (220 and 254 nm), and quantitation by comparison with an internal standard. The 10-micron C18 muBondapak column was eluted with 45% (vol/vol) methanol-65% (vol/vol) phosphate buffer. The precision was 4.2 and 5.6% at 50 and 10 micrograms/ml, respectively. The assay was linear up to concentrations of 100 micrograms/ml, with recoveries of 90.4 to 110.5% from serum. The assay was sensitive to 0.4 micrograms of azlocillin per ml. The short turnover time (14 min) and small serum sample size (20 microliters) make the assay ideal for therapeutic drug monitoring and clinical pharmacokinetic studies.

Azlocillin↗
PubMed1983

Protein ADP-ribosylation in rat liver cytosol.

ADP and poly ADP-ribosylation are post-translational modifications of proteins which have been reported to occur essentially in eucaryotic nuclei. This phenomenon has been shown to interfere with a great variety of biological functions (cell differentiation, DNA repair, malignant transformation...). In this paper, we demonstrate for the first time that ADP-ribosylation occurs also in cytosol (120 000 g supernatant) and that several cytosolic proteins can be ADP-ribosylated in rat liver.

Adenosine Diphosphate Ribose↗