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Biomedical subjects

E Windler

Publications and source records attributed to E Windler.

At least 55 records · Page 3Linked to original sources
PubMed1993

Performance of Helicobacter pylori acid extract and urease enzyme-linked immunosorbent assays in relation to 14C-urea breath test.

The 14C-urea breath test has been shown to be a reliable non-invasive method to detect the presence or absence of H. pylori infection. Alternatively, a number of techniques have been devised to detect circulating antibodies against H. pylori in serum, the most commonly used being enzyme-linked immunosorbent assays (ELISA). In the present study we compared the value of two ELISA antigen preparations, an acid glycine extract and a urease preparation, in relation to the results achieved in a 14C-urea breath test. Seventy-five gastroenterology outpatients were screened for the presence of H. pylori infection using the urea breath test. At the same time serum specimens were obtained. Thirty-seven patients had a positive breath test, i.e. they expired more than 2% of the oral 14C test dose within 60 min. Using the breath test as reference, sensitivity and specificity for the acid extract were 89.2% and 84.2% respectively, and for the urease ELISA 81.1% and 89.5%. Agreement between the two ELISAs was found in 82.7%, overall agreement between all three tests was observed in 77.3%. All three tests were found to be useful for monitoring therapy directed against H. pylori.

Antigens, Bacterial↗
PubMed1993

Apolipoprotein B mRNA editing in 12 different mammalian species: hepatic expression is reflected in low concentrations of apoB-containing plasma lipoproteins.

Two different isoproteins are encoded by the apolipoprotein (apo) B gene, apoB-48 and apoB-100. ApoB-48, core component of intestinally derived chylomicrons, has an accelerated plasma turnover as compared with the full-length protein apoB-100. A posttranscriptional modification of the apoB mRNA by conversion of cytidine into uridine at nucleotide position 6666 changes the genomically encoded glutamine codon CAA at amino acid residue 2153 into a translational stop codon UAA. This mRNA editing explains the formation of the truncated isoform apoB-48. In the present investigation editing of apoB mRNA in liver and intestine from 12 different mammalian species was measured by a quantitative primer extension analysis of reverse-transcribed and polymerase chain reaction- (PCR) amplified apoB mRNA in order to determine whether i) editing of apoB mRNA is generally restricted to the intestine or may also be found in the liver of other species than rodents, and ii) hepatic expression of apoB mRNA editing influences lipoprotein concentrations in plasma. Intestinal apoB mRNA was edited at high levels in all species, 40% in sheep, 73% in horse, 82% in pig, 84% in dog, 84% in cat, 87% in guinea pig, 88% in rat, 89% in mouse, and > 90% in human, monkey, cow, and rabbit. In liver apoB mRNA was edited to 18% in dog, to 43% in horse, to 62% in rat, and to 70% in mouse. Low levels of editing below 1% were detected in liver of rabbit and guinea pig. In contrast, hepatic apoB mRNA from human, monkey, pig, cow, sheep, and cat liver was not edited. The results of the primer extension analysis were confirmed by cloning and sequencing of the PCR products from dog, horse, cat, guinea pig, sheep, and cow for all of which the apoB cDNA sequence had not been established by previous investigations. Primer extension analysis of apoB mRNA from dog intestine and dog liver indicated C/U editing at C6655 in addition to C6666. Cloning and sequencing of apoB cDNA from dog liver and intestine confirmed additional C/U editing at C6655 which changes ACA for threonine at amino acid residue 2149 into AUA for isoleucine. Synthesis and secretion of apoB-48-containing lipoproteins from liver was demonstrated by pulse labeling of freshly isolated horse hepatocytes and immunoprecipitation with apoB-specific antibodies or density gradient ultracentrifugation. The concentrations of VLDL, LDL, and HDL in all species were determined after fractionation by density gradient ultracentrifugation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Regulation of the hepatic removal of chylomicron remnants and beta-very low density lipoproteins in the rat.

The contribution of the low density lipoprotein (LDL) receptor to the removal of chylomicron remnants was determined in vitro and in vivo by using interventions that up- or down-regulate the LDL receptor but not the LDL receptor-related protein (LRP). In vitro, chylomicron remnants and beta-very low density lipoprotein (VLDL) bind to the LDL receptor on endosomal membranes; their binding can be competed by LDL and beta-VLDL and the binding capacity is greatly augmented in membranes from estradiol-treated rats. Likewise, estradiol treatment almost doubled the removal of chylomicron remnants during a single pass through perfused rat livers. However, in vivo the removal of chylomicron remnants and beta-VLDL was very rapid even in untreated rats so that the effect of the stimulation by estradiol was barely detectable when trace amounts of lipoproteins were injected. Yet, when saturating doses of either lipoprotein were injected, the effect of estradiol treatment on the removal of chylomicron remnants and beta-VLDL was readily disclosed. In rats fed a diet containing lard, cholesterol, and bile acids, removal of chylomicron remnants or beta-VLDL was significantly retarded. Likewise, perfused livers from diet-fed rats removed only a mean of 16% of chylomicron remnants during a single passage as compared to 29% in livers from control animals. Also, when large doses of beta-VLDL had been infused into rats for 4 h, in subsequent perfusions of the livers the removal of chylomicron remnants was decreased to 11%. From these results it is concluded that the LDL receptor mediates the hepatic removal of a major fraction of chylomicron remnants and beta-VLDL.

Animals↗
PubMed1991

The human asialoglycoprotein receptor is a possible binding site for low-density lipoproteins and chylomicron remnants.

Binding and internalization of chylomicron remnants from rat mesenteric lymph by HepG2 cells was inhibited by both excess remnants and low-density lipoprotein (LDL) to the same extent. Ligand blots revealed binding of remnants and LDL to the LDL receptor. Measures regulating LDL receptor activity greatly influenced the binding of remnants: ethinyloestradiol, the hydroxymethylglutaryl-CoA reductase inhibitor pravastatin and the absence of LDL all increased binding, whereas high cell density or the presence of LDL decreased binding. Also, asialofetuin, asialomucin, the neoglycoprotein galactosyl-albumin and an antibody against the asialoglycoprotein receptor all decreased substantially the binding of remnants. At high cell density, binding internalization and degradation of chylomicron remnants was inhibited by up to 70-80%, yet binding of LDL was inhibited by no more than 20-30%. In cross-competition studies, the binding of 125I-asialofetuin was efficiently competed for by asialofetuin itself or by the antibody, and also by LDL and remnants, yet remnants displayed an approx. 100-fold higher affinity than LDL. Likewise, remnants of human triacylglycerol-rich lipoproteins and asialofetuin interfered with each others' binding to HepG2 cells or human liver membranes. It is concluded that the LDL receptor mediates the internalization of chylomicron remnants into hepatocytes depending on its activity, according to demand for cholesterol. Additionally, the asialoglycoprotein receptor may contribute to the endocytosis of LDL, but predominantly of chylomicron remnants.

Animals↗
PubMed1991

[Hyperlipidemias].

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Combined Modality Therapy↗
PubMed1990

[Metabolism of chylomicrons and very low density lipoproteins].

The liver supplies peripheral tissues with lipoproteins containing triglycerides, a source of energy, and cholesterol, a structural component of cell membranes. The liver is also capable of taking up lipoproteins and excreting cholesterol in the bile. Because of this unique metabolic role the endocytosis of lipoproteins by the liver was studied. Lipoproteins bind through their component proteins to the low density lipoprotein-receptor of hepatocytes. Apolipoprotein B of low density lipoproteins exhibits fairly low affinity, whereas apolipoprotein E of the postlipolytic remnants of very low density lipoproteins and chylomicrons bind with much higher affinity, which results in a much shorter residence time of these lipoproteins in plasma. Premature uptake is prevented by the C-apolipoproteins, yet. Changes in the phospholipid composition of the lipoproteins during the intraplasmatic lipolysis lead to loss of C-apolipoproteins enabling interaction of apolipoprotein E with the receptors of the liver. Binding is followed by endocytosis into endosomes, which fuse to multivesicular bodies. The contents gets catabolized by hydrolytic enzymes of lysosomes thus becoming available to the cell.

Apolipoproteins↗
PubMed1990

Influence of the acyl-coenzyme A:cholesterol--acyltransferase inhibitor octimibate on cholesterol transport in rat mesenteric lymph.

The effect of the new inhibitor of acyl-coenzyme A:cholesterol-acyltransferase, octimibate (sodium 8-[1,4,5-triphenyl-1H-imidazole-2yl)-oxy)octanoate), on the cholesterol transport in rat mesenteric lymph was evaluated. During intraduodenal infusion of a triglyceride-phospholipid emulsion, volume and triglyceride concentration of lymph collected from a mesenteric lymph fistula remained constant in control and treated rats. After addition of 3.75 mg 3H-cholesterol/h to the intraduodenal infusion, cholesterol content of lymph increased to about double the basic concentration in control rats. Yet there was no significant change of lymph cholesterol in treated animals, which had received 40 mg octimibate followed by ca. 120 mg/24 h x kg body weight octimibate added to the intraduodenal infusion. Up to 35% of the infused dose of 3H-cholesterol were recovered in lymph of control rats, in contrast to only 23% in lymph of treated rats. It is concluded that the inhibition of the intestinal acyl-coenzyme A:cholesterol-acyltransferase by octimibate may prevent the increase of cholesterol in mesenteric lymph induced by dietary cholesterol.

Animals↗