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Biomedical subjects

J Lüthy

Publications and source records attributed to J Lüthy.

65 records · Page 4Linked to original sources
PubMed1976

Stereology of liver biopsies from healthy volunteers.

The stereological model and the base-line data of normal human liver needle biopsy-specimens are presented. Four reference systems were introduced: 1 cm3 of liver tissue, 1 cm3 of hepatocyte, 1 cm3 of hepatocytic cytoplasm and the volume of an average "mononuclear" hepatocyte. The sampling was done at three levels of magnification (1,000 X, 5,000 X and 10,000 X). A lobular differentiation was not considered. The baseline data show strikingly small variations (s.e. less than 10%) within the individual biopsy specimen and within the group of four biopsies. There is no principal difference between human beings presented here, rats, mice and dogs. Only the mean individual volume of human hepatocytes is clearly larger than in rodents. The problems and limitations of stereological work on liver biopsy specimens are discussed.

Animals↗
PubMedDate not supplied

Toxicity and mutagenicity of anthraquinones from Aspergillus chevalieri.

More than 100 strains of the Aspergillus glaucus group were cultivated on synthetic media for 11 days at 28 degrees C. Organic extracts of fungal material were screened by thin-layer chromatography (TLC) for the mycotoxins aflatoxins B1,2 and G1,2, sterigmatocystin, ochratoxin A, gliotoxin, patulin, and xanthocillin X. None of these toxins were produced in detectable amounts under experimental conditions. Nevertheless, organic extracts exhibited high toxicity after intraperitoneal (i.p.) administration in mice. Aspergillus chevalieri strain ZT 8268 was selected for further investigation of its toxic metabolites. The main toxic action was attributed to the four anthraquinone derivatives, physicion, physcionanthrone B, physciondianthrone, and erythroglaucin, which were isolated and identified. No toxic effects were found after oral administration. Using the Salmonella/mammalian microsome test, mutagenic activity (frame-shift) was detected in strain TA 1537 in the presence of S-9 liver microsome preparation.

Animals↗
PubMedDate not supplied

Detection of pork in heated meat products by the polymerase chain reaction.

A new method for the specific, sensitive, and semiquantitative detection of pork (Sus scrofa) in heat-treated meat products has been developed. DNA was isolated from meat samples by using a DNA-binding resin and subjected to polymerase chain reaction (PCR) analysis. First, oligonucleotides yielding a specific 137-base-pair (bp) fragment from eucaryotic DNA amplified from a highly conserved region of the 18-S ribosomal gene was used to assess DNA quality. Second, the presence of pork DNA was determined with specific oligonucleotides yielding a 108-bp fragment amplified from the porcine growth hormone gene. The test detected pork in fresh or heated meat mixtures of pork in beef at levels below 2%. This approach was superior to commercially available immunological tests that were not able to detect levels of pork less than 20% in cooked meat or less than 10% in fresh meat.

Animals↗
PubMedDate not supplied

Detection of Salmonella spp. in eggs: DNA analyses, culture techniques, and serology.

A polymerase chain reaction (PCR) method for direct detection of Salmonella spp. in whole-shell eggs is described. The method does not require isolating strains. Preenrichment, rapid DNA isolation, and a nested PCR system targeting the invA gene enabled detection of the genus Salmonella. The specific nested PCR product of 283 base pairs was formed from all 21 serovars, including 43 Salmonella strains tested. No PCR product was formed from 56 non-Salmonella enterobacteriacea and other bacterial strains tested. Experiments with artificially contaminated eggs showed a detection limit of about 10(3)-10(4) colony-forming units (cfu)/egg before and about 1-10 cfu/egg after preenrichment. In analysis of 180 single eggs from 4 flocks and 36 pools of 5 eggs each from another 4 flocks from the same producer, Salmonella spp. were detected in 5 of 90 eggs from 2 different flocks. Determination of anti-Salmonella antibodies in eggs yielded positive results for 2 additional and the 2 PCR-positive flocks. In contrast, classical selective culture detected Salmonella spp. in only 1 of 100 eggs in one flock when 100 eggs from each flock were analyzed.

Bacteriological Techniques↗
PubMedDate not supplied

Polymerase chain reaction-restriction fragment length polymorphism analysis: a simple method for species identification in food.

The polymerase chain reaction (PCR) technique was applied to meat species identification in marinated and heat-treated or fermented products and to the differentiation of closely related species. DNA was isolated from meat samples by using a DNA-binding resin and was subjected to PCR analysis. Primers used were complementary to conserved areas of the vertebrate mitochondrial cytochrome b (cytb) gene and yielded a 359 base-pair (bp) fragment, including a variable 307 bp region. Restriction endonuclease analysis based on sequence data of those fragments was used for differentiation among species. Restriction fragment length polymorphisms (RFLPs) were detected when pig, cattle, wild boar, buffalo, sheep, goat, horse, chicken, and turkey amplicons were cut with AluI, RsaI, TaqI, and HinfI. Analysis of sausages indicates the applicability of this approach to food products containing meat from 3 different species. The PCR-RFLP analytical method detected pork in heated meat mixtures with beef at levels below 1%, and the method was confirmed with porcine- and bovine-specific PCR assays by amplifying fragments of their growth hormone genes. Inter- and intraspecific differences of more than 22 animal species with nearly unknown cytb DNA sequences, including hoofed mammals (ungulates), and poultry were determined with PCR-RFLP typing by using 20 different endonucleases. This typing method allowed the discrimination of game meats, including stag, roe deer, chamois, moose, reindeer, kangaroo, springbok, and other antelopes in marinated and heat-treated products.

Animals↗