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Biomedical subjects

W Gerok

Publications and source records attributed to W Gerok.

409 records · Page 23Linked to original sources
PubMedDate not supplied

Influence of hydroxylation and conjugation of bile salts on their membrane-damaging properties--studies on isolated hepatocytes and lipid membrane vesicles.

To characterize the relative toxicity of different bile salts, isolated hepatocytes were incubated with different concentrations of one bile salt or with identical concentrations of different bile salts and their conjugates. Incubation lasted for 1 hr; samples were taken at intervals and studied for enzyme release, urea synthesis and stimulation by glucagon, and by electron microscopy. While the trihydroxylated bile salt, taurocholate, did not produce alterations at concentrations up to 1,500 microM, the dihydroxylated salts, chenodeoxy- and deoxycholate, caused enzyme release and membrane lysis, and inhibited urea synthesis at concentrations above 500 microM. In contrast, ursodeoxycholate was ineffective at concentrations up to 1,500 microM. Conjugation of these bile salts did not result in significant differences with the exception of deoxycholate conjugates which induced enzyme leakage more rapidly. Studies of lipid membrane vesicles revealed corresponding alterations. The monohydroxylated salt, taurolithocholate, caused cellular damage as indicated by enzyme loss and impairment of hormonal sensitivity of cells at low concentrations (30 to 100 microM). Dihydroxylated salts produced a different time course of membrane leakage, ultrastructural changes and release of volume marker and lipid in liposomes, suggesting a possible different mechanism of damage induced by this bile salt. Both systems can readily be used to study bile salt membrane interactions.

Animals↗
PubMedDate not supplied

Spot-blot hybridization assay for the detection of hepatitis B virus DNA in serum: factors determining its sensitivity and specificity.

Factors determining the sensitivity and specificity of the spot-blot hybridization technique for the detection of hepatitis B virus DNA in serum were systematically investigated. Methods for pretreatment of serum samples, mode of application of the samples to the transfer membranes, blot treatment and hybridization conditions were all found to affect the sensitivity of the assay. The optimum hybridization procedure was found to be incubation of serum samples with salt, NaOH, formaldehyde and detergent, followed by spot application of the samples. This method specifically detected hepatitis B virus DNA in serum with a sensitivity 5 to 15 times higher than the presently used assay procedures.

DNA, Viral↗
PubMedDate not supplied

Bile salt shift from albumin to high-density lipoprotein in cholestasis.

The distribution of [3H]taurocholate between albumin and the lipoproteins of serum of patients with various diseases in which lipoprotein metabolism and/or bile salt concentrations were altered and of healthy control subjects was investigated by means of the density gradient centrifugation method. 1. In control sera, bile salts distribute mainly between albumin and high-density lipoprotein. An amount of 19.7 +/- 3.6% (mean +/- S.D., n = 6) of the total serum bile salts was found in the high-density lipoprotein fraction of the density gradient. 2. In sera of nonicteric patients, the distribution pattern of [3H]taurocholate in the fractions of the density gradient showed no essential differences to normal serum. The relative amounts of taurocholate in the albumin-containing fractions and the high-density lipoprotein fractions were dependent on the concentrations of albumin and high-density lipoprotein. 3. In sera of deeply jaundiced patients, the distribution pattern of [3H]taurocholate showed two distinct peaks in the high-density lipoprotein density range, one of which codistributed with high-density lipoprotein2 and the other with a high-density fraction of high-density lipoprotein3 in the density range of 1.19 to 1.23 gm per ml. The distribution of [3H]taurocholate between albumin and high-density lipoprotein was markedly shifted toward high-density lipoprotein. No [3H]taurocholate association with lipoprotein X was observed. 4. Bilirubin was found to cause a shift of taurocholate from albumin to high-density lipoprotein in vitro. It is proposed that bilirubin is responsible, at least in part, for the observed shift in icteric sera.

Adult↗
PubMedDate not supplied

Hepatocellular carcinoma in alcoholic liver disease: no evidence for a pathogenetic role of hepatitis B virus infection.

Hepatocellular carcinoma tissues from HBsAg-negative patients with chronic alcoholic liver disease were investigated for the presence of hepatitis B virus DNA. Southern blot analyses of DNA extracted from the hepatocellular carcinomas were negative for hepatitis B virus DNA in all 17 patients examined, at a level of sensitivity of less than 0.01 genome equivalent per cell. Similarly, in liver tissues from another 30 patients with alcoholic cirrhosis without hepatocellular carcinoma, no hepatitis B virus DNA was detectable. We conclude that in our patients there is no molecular evidence for a contribution of hepatitis B virus infection to the development of hepatocellular carcinoma in alcoholic liver disease.

Adult↗
PubMedDate not supplied

Amplification of unknown DNA sequences by sequence-independent nested polymerase chain reaction using a standardized adaptor without specific primers.

A new procedure for sequence-independent PCR amplification of DNA fragments is described. DNA from pUC18 plasmid was used as a test DNA. It was digested with a frequently cutting restriction enzyme (Sau3A), generating sticky ends. The DNA was ligated to a synthetic, non-phosphorylated adaptor and subsequently amplified in a nested PCR using two oligonucleotides with sequences derived from the adaptor. As little as 1 fg of pUC18 DNA could be detected by this procedure. The product was analyzed on a gel and hybridized with a pUC18-specific probe. The sequence-independent nested PCR was repeated with different amounts of pUC18 DNA in the presence of an excess of non-specific DNA. In these experiments, pUC18 DNA fragments were amplified in a concentration-dependent manner. After hybridization with a digoxigenin dUTP-labelled pUC18 DNA probe, 1 fg of pUC18 DNA could still be detected. This method allows rapid screening of blood for low titred and mutated viruses in which primer binding sites are not conserved.

Base Sequence↗