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Biomedical subjects

E Leitner

Publications and source records attributed to E Leitner.

At least 19 recordsLinked to original sources
PubMed2000

Upregulation of bradykinin B1-receptor expression after myocardial infarction.

To determine the influence of the myocardial infarction (MI) on bradykinin B1-receptor (B1R) regulation, we studied its expression in the left ventricle (LV) after MI. Rats were submitted to a permanent occlusion of the left coronary artery. Six hours, 24 h and 6 days after MI or after sham operation, left ventricular pressure (LVP) and dP/dt(max) were measured. LV-total RNA was extracted and B1R expression was analysed by a RNase-protection assay (each group n = 6). LVP and dP/dt(max) were impaired at all time points after MI. Basal B1R expression was not detectable in controls. Six hours after MI, the B1R expression was upregulated and reached a maximum 24 h after MI (4 fold vs. 6 h). Six days post-MI, B1R expression returned to levels found 6 h after MI. These data are the first demonstration for an induced myocardial B1R expression in an in vivo model of MI.

Animals↗
PubMed2000

Contribution of Are1p and Are2p to steryl ester synthesis in the yeast Saccharomyces cerevisiae.

In the yeast Saccharomyces cerevisiae, two acyl-CoA:sterol acyltransferases (ASATs) that catalyze the synthesis of steryl esters have been identified, namely Are2p (Sat1p) and Are1p (Sat2p). Deletion of either ARE1 or ARE2 has no effect on cell viability, and are1are2 double mutants grow in a similar manner to wild-type despite the complete lack of cellular ASAT activity and steryl ester formation [Yang, H., Bard, M., Bruner, D. A., Gleeson, A., Deckelbaum, R. J., Aljinovic, G., Pohl, T. M., Rothstein, R. & Sturley, S. L. (1996) Science 272, 1353-1356; Yu, C., Kennedy, J., Chang, C. C. Y. & Rothblatt, J. A. (1996) J. Biol. Chem. 271, 24157-24163]. Here we show that both Are2p and Are1p reside in the endoplasmic reticulum as demonstrated by measuring ASAT activity in subcellular fractions of are1 and are2 deletion strains. This localization was confirmed by fluorescence microscopy using hybrid proteins of Are2p and Are1p fused to green fluorescent protein (GFP). Lipid analysis of are1 and are2 deletion strains revealed that Are2p and Are1p utilize sterol substrates in vivo with different efficiency; Are2p has a significant preference for ergosterol as a substrate, whereas Are1p esterifies sterol precursors, mainly lanosterol, as well as ergosterol. The specificity towards fatty acids is similar for both isoenzymes. The lack of steryl esters in are1are2 mutant cells is largely compensated by an increased level of free sterols. Nevertheless, terbinafine, an inhibitor of ergosterol biosynthesis, inhibits growth of are1are2 cells more efficiently than growth of wild-type. In a growth competition experiment are1are2 cells grow more slowly than wild-type after several rounds of cultivation, suggesting that Are1p and Are2p or steryl esters, the product formed by these two enzymes, are more important in the natural environment than under laboratory conditions.

Acyltransferases↗
PubMed2000

Elo1p-dependent carboxy-terminal elongation of C14:1Delta(9) to C16:1Delta(11) fatty acids in Saccharomyces cerevisiae.

Saccharomyces cerevisiae medium-chain acyl elongase (ELO1) mutants have previously been isolated in screens for fatty acid synthetase (FAS) mutants that fail to grow on myristic acid (C14:0)-supplemented media. Here we report that wild-type cells cultivated in myristoleic acid (C14:1Delta(9))-supplemented media synthesized a novel unsaturated fatty acid that was identified as C16:1Delta(11) fatty acid by gas chromatography-mass spectroscopy. Synthesis of C16:1Delta(11) was dependent on a functional ELO1 gene, indicating that Elo1p catalyzes carboxy-terminal elongation of unsaturated fatty acids (alpha-elongation). In wild-type cells, the C16:1Delta(11) elongation product accounted for approximately 12% of the total fatty acids. This increased to 18% in cells that lacked a functional acyl chain desaturase (ole1Delta mutants) and hence were fully dependent on uptake and elongation of C14:1. The observation that ole1Delta mutant cells grew almost like wild type on medium supplemented with C14:1 indicated that uptake and elongation of unsaturated fatty acids were efficient. Interestingly, wild-type cells supplemented with either C14:1 or C16:1 fatty acids displayed dramatic alterations in their phospholipid composition, suggesting that the availability of acyl chains is a dominant determinant of the phospholipid class composition of cellular membranes. In particular, the relative content of the two major phospholipid classes, phosphatidylethanolamine and phosphatidylcholine, was strongly dependent on the chain length of the supplemented fatty acid. Moreover, analysis of the acyl chain composition of individual phospholipid classes in cells supplemented with C14:1 revealed that the relative degree of acyl chain saturation characteristic for each phospholipid class appeared to be conserved, despite the gross alteration in the cellular acyl chain pool. Comparison of the distribution of fatty acids that were taken up and elongated (C16:1Delta(11)) to those that were endogenously synthesized by fatty acid synthetase and then desaturated by Ole1p (C16:1Delta(9)) in individual phospholipid classes finally suggested the presence of two different pools of diacylglycerol species. These results will be discussed in terms of biosynthesis of different phospholipid classes via either the de novo or the Kennedy pathway.

Acetyltransferases↗
PubMed1999

Development of a simple sample preparation technique for gas chromatographic-mass spectrometric determination of nicotine in edible nightshades (Solanaceae).

The purpose of this study was to develop a rapid analytical method for the reliable determination of low concentrations of nicotine in foods for large numbers of samples. Food material was extracted using a simple liquid-liquid extraction method. For processed foods, further clean-up steps had to be employed to eliminate interfering compounds. The determination of nicotine was performed by gas chromatography-mass spectrometry. Quantitative analysis was accomplished using deuterium labeled nicotine as an internal standard. Recoveries of over 95% were obtained for a single step extraction, as well as for a multiple-stage extraction procedure, respectively. The method has been applied to the determination of nicotine in edible nightshades (i.e. tomatoes, potatoes and aubergines) and their processed products.

Air↗
PubMed1999

PDR16 and PDR17, two homologous genes of Saccharomyces cerevisiae, affect lipid biosynthesis and resistance to multiple drugs.

The Saccharomyces cerevisiae open reading frame YNL231C was recently found to be controlled by the multiple drug resistance regulator Pdr1p. Here we characterize YNL231C (PDR16) and its homologue YNL264C (PDR17). Deletion of PDR16 resulted in hypersensitivity of yeast to azole inhibitors of ergosterol biosynthesis. While no increase in drug sensitivity was found upon deletion of PDR17 alone, a Deltapdr16,Deltapdr17 double mutant was hypersensitive to a broad range of drugs. Both mutations caused significant changes of the lipid composition of plasma membrane and total cell extracts. Deletion of PDR16 had pronounced effects on the sterol composition, whereas PDR17 deletion mainly affected the phospholipid composition. Thus, Pdr16p and Pdr17p may regulate yeast lipid synthesis like their distant homologue, Sec14p. The azole sensitivity of the PDR16-deleted strain may be the result of imbalanced ergosterol synthesis. Impaired plasma membrane barrier function resulting from a change in the lipid composition appears to cause the increased drug sensitivity of the double mutant strain Deltapdr16,Deltapdr17. The uptake rate of rhodamine-6-G into de-energized cells was shown to be almost 2-fold increased in a Deltapdr16,Deltapdr17 strain as compared with wild-type and Deltapdr5 strains. Collectively, our results indicate that PDR16 and PDR17 control levels of various lipids in various compartments of the cell and thereby provide a mechanism for multidrug resistance unrecognized so far.

Base Sequence↗
PubMed1999

mRNA quantification of C-type natriuretic peptide in brain areas of rodents.

C-type natriuretic peptide (CNP) is regarded as an endothelium-derived vasodilator and might therefore have an important role in controlling vascular tone and remodeling. Because CNP also is expressed in the brain, it is considered to be a neurotransmitter. The present study compares expression levels of CNP mRNA in distinct areas of the mouse brain with the expression pattern in the rat brain. A distinct expression of CNP was found in all investigated areas with the exception of the mouse striatum. In both rodents, high CNP expression was detected in the tegmentum.

Animals↗
PubMed1999

Determination of the nicotine content of various edible nightshades (Solanaceae) and their products and estimation of the associated dietary nicotine intake.

This investigation was initiated as a result of proposals in the literature that dietary nicotine intake could contribute to the level of nicotine metabolites in biological fluids such as salivary cotinine concentration. Nicotine concentration was determined in several frequently consumed vegetables from the nightshade family (Solanaceae) (i.e., tomatoes, potatoes, aubergines, and peppers), as well as in some of their processed products. The edible Solanaceae fruit analyzed in this investigation were found to contain relatively consistent amounts of nicotine in the range of 2-7 microg/kg for fresh fruits. Nevertheless, the nicotine concentrations of the investigated tomato varieties decreased significantly with increasing degree of ripening of the fruits. In addition, a variety of black as well as green teas was investigated for the nicotine content. Nicotine content in tea leaves was found to be highly variable and sometimes much larger than in the Solanaceae fruits. On the basis of the observed concentrations and the respective food consumption data for different countries, a distributive analysis of the results suggests that the mean daily dietary nicotine intake for the population of the countries for which consumption data were available is approximately 1.4 microg/day, 2.25 microg/day at the 95th percentile.

Diet↗
PubMed1996

Variability of fatty acid content in pumpkin seeds (Cucurbita pepo L.).

Pumpkin (Cucurbita pepo L.) seed oil is a common salad oil which is produced in Slovenia, Hungary and the southern parts of Austria. It is dark green and has a high content of free fatty acids. The seed itself can be eaten. Due to its colour and the foam formation, the oil cannot be used for cooking. The content of vitamin E, especially gamma-tocopherol, is very high. The oil content of the pumpkin seed is about 50%. The variability in the oil content is very high resulting from a broad genetic diversity. Thus a breeding programme for increasing the oil productivity is very promising. The four dominant fatty acids are palmitic, stearic, oleic and linoleic acids. These four fatty acids make up 98 +/- 0.13% of the total amount of fatty acids, others being found at levels well below 0.5%.

Austria↗
PubMed1994

The peptide synthetase catalyzing cyclosporine production in Tolypocladium niveum is encoded by a giant 45.8-kilobase open reading frame.

Cyclosporin A, a potent and clinically-important immunosuppressive drug (SandimmunR), is synthesized from its precursor amino acids by cyclosporin synthetase, a single multi-functional enzyme. In this study we report the cloning of the corresponding coding region of this synthetase. It contains an open reading frame of 45.8 kb which encodes a peptide with a calculated M(r) of 1,689,243. The predicted gene product contains 11 amino-acid-activating domains that are very similar to one another and to the domains of other peptide synthetases. Seven of these domains harbour N-methyltransferase functions. This is the largest genomic ORF described so far.

Amino Acid Sequence↗
PubMed1991

Penicillium chrysogenum extracellular acid phosphatase: purification and biochemical characterization.

An extracellular acid phosphatase (EC 3.1.3.2) from crude culture filtrate of Penicillium chrysogenum was purified to homogeneity using high-performance ion-exchange chromatography and size-exclusion chromatography. SDS-PAGE of the purified enzyme exhibited a single stained band at an Mr of approx. 57,000. The mobility of the native enzyme indicated the Mr to be 50,000, implying that the active form is a monomer. The isoelectric point of the enzyme was estimated to be 6.2 by isoelectric focusing. Like acid phosphatases from several yeasts and fungi the Penicillium enzyme was a glycoprotein. Removal of carbohydrate resulted in a protein band with an Mr of 50,000 as estimated by SDS-PAGE, suggesting that 12% of the mass of the enzyme was carbohydrate. The enzyme was catalytically active at temperatures ranging from 20 degrees C to 65 degrees C with a maximum activity at 60 degrees C and the pH optimum was at 5.5. The Michaelis constant of the enzyme for p-nitrophenyl phosphate was 0.11 mM and it was inhibited competitively by inorganic phosphate (ki = 0.42 mM).

Acid Phosphatase↗
PubMed1991

Molecular characterization and functional analysis in Aspergillus nidulans of the 5'-region of the Penicillium chrysogenum isopenicillin N synthetase gene.

The isopenicillin N synthetase gene (pcbC) was isolated from a genomic library of Penicillium chrysogenum BC39813, a penicillin production strain. The nucleotide sequence, including 555 bp upstream of the translation start site was determined. Various deletions within the pcbC 5'-region were constructed and linked to the Escherichia coli lacZ gene. An Aspergillus nidulans argB strain was transformed with DNA of these constructions. The region essential for promoter function could be localized between positions -307 and -89 by analyzing beta-galactosidase expression of transformants containing a single copy of the corresponding plasmid integrated at the homologous argB locus. A region responsible for regulatory effects concerning nitrogen metabolism was identified by determining beta-galactosidase activities in cell-lysates of transformants cultivated under varying growth conditions. Two major transcription start sites at positions -131 and -132, as well as a further upstream located site at position -397 +/- 1 could be located by primer extension studies employing RNA isolated from P. chrysogenum BC39813.

Amino Acid Sequence↗
PubMed1989

[A sub-pectoral gliding flap for covering the lateral triangle of the neck].

The subpectoral connective tissue can be isolated and transferred on a vascular pedicle (pectoral branch of the thoracoacromial artery). It was demonstrated by cadaver dissection that this flap covers the fossa supraclavicularis and can reach the mandibular angle and in some cases the cheek. This flap was used clinically to envelope the fibrotic brachial plexus after neurolysis, in the treatment of a pain syndrome in which several simple neurolyses had previously failed.

Aged↗
PubMed1988

[Ethylene oxide-induced antibodies and hypersensitivity reactions in hemodialysis].

The presence of antibodies against ethylene oxide, which is used for sterilization of dialyzers, was evaluated in 52 hemodialysis patients (30 male, 22 female). The aim of the prospective study was to evaluate a possible correlation of these antibodies with hypersensitivity reactions during hemodialysis. By means of a radio-allergo-sorbent-test (RAST) only 3.9% (2 patients) were detected to have ethylene oxide antibodies. There was no significant correlation between antibodies on the one hand, and symptoms, eosinophilia and IgE-elevation on the other hand. We could not find ETO-induced hypersensitivity reactions in our study population. Thorough rinsing and sufficient storage time of the dialyzers might be the reasons for these findings.

Adult↗
PubMed1980

[Acute implantation technique of the ellipsoid heart for clinical left ventricular assistance (author's transl)].

The results of the first clinical trials of left ventricular assist devices are not encouraging. The only indication at present is in patients with cardiac failure after cardiac operations. The acute type of ellipsoid heart described in this paper-displays a canulation technique where the inflow canula inserted in the left ventricular cavity via the left atrium and the outflow canula is directly connected to the aortic canula of the cardiopulmonary bypass. The haemodynamic response shows the efficacy of this system. The circulation can be maintained in severe cardiac failure, as well as in ventricular fibrillation and cardiac arrest. On the basis of data obtained in experiments on 7 female calves this system is considered worthy of clinical trial.

Aorta↗
PubMed1979

[Plasma catecholamines in open heart surgery and abdominal operations using a combined electrical stimulation analgesia (author's transl)].

Changes of plasma catecholamines during surgery performed in the presence of a combined electrical stimulation analgesia were studied in 11 patients undergoing open heart surgery and in 5 patients undergoing abdominal operations. Stimulation was applied through 2 needles attached subcutaneously to each ear. In 8 of the 11 patients undergoing open heart surgery an up to 20 fold increase in the level of adrenaline in plasma was observed intraoperatively indicating a massive activation of the adrenal medulla. Adrenaline remained elevated also in the postoperative period. The level of noradrenaline did not increase either during the intra- or during the postoperative period. In contrast no changes in adrenaline or noradrenaline could be demonstrated in the remaining 3 patients in whom the concentration of the catecholamines was in the lower normal range. In 5 patients with abdominal surgery noradrenaline was elevated additionally to the increase of adrenaline in the intra- and postoperative period. The increase in the activity of the sympathetic nervous system was associated in these patients with an increase in heart rate and systolic as well as diastolic blood pressure. On the basis of these results the use of a combined electrical stimulation analgesia for abdominal surgery in patients at risk and for open heart surgery is questioned.

Abdomen↗