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Biomedical subjects

K Leopold

Publications and source records attributed to K Leopold.

At least 19 recordsLinked to original sources
PubMed2006

[Hepatology].

Therapy by pegylated interferon-alpha (PEG-IFN-alpha), lamivudine and adefovir have significantly improved treatment perspectives for patients with chronic hepatitis B. New nucleos(t)ide analogues should permit the development of more effective combination therapies. In autoimmune hepatitis, if there is no response or an intolerance to therapy with prednisone and imurek, administration of mycophenolate mofetil should be envisaged. Ursodeoxycholic acid (UDCA) therapy, at a dosage of 13-15 mg/ kg/day, remains the treatment of choice for primary biliary cirrhosis and should be administered at an early stage to improve patients' survival. In the treatment of nonalcoholic fatty liver disease, thiazolidinediones show considerable promise, but further clinical studies are required in order to prove their efficacity and safety.

Antiviral Agents↗
PubMed2003

Medical management of obesity.

BACKGROUND: Obesity is associated with elevated morbidity and death rates. The World Health Organization defines obesity as a chronic disease. The percentage of obese persons is increasing worldwide. Many different treatment modalities are available. Long-term success rates are not convincing. RESEARCH FOCUS: Overweight and obesity should be treated in an interdisciplinary and multimodal approach. The best results in loosing body weight, especially body fat use very low calorie diets followed by a fat-reduced, carbohydrate-rich diets. Weight-loss drugs should be used only in a weight-loss program including diet and physical activity. Surgical intervention is necessary in a small group of persons refractory to conservative obesity treatment. CONCLUSIONS: New structured guidelines oriented and quality controlled programs for treatment of obese patients are necessary.

Diet, Reducing↗
PubMed2000

Cardiolipin, alpha-D-glucopyranosyl, and L-lysylcardiolipin from gram-positive bacteria: FAB MS, monofilm and X-ray powder diffraction studies.

Cardiolipin preparations from Streptococcus B, Listeria welshimeri, Staphylococcus aureus, and a glucosyl and lysyl derivative of cardiolipin were analysed for fatty acid composition and fatty acid combinations. Three different fatty acid patterns are described and up to 17 molecular species were identified in Streptococcus B lipids by high resolution FAB MS. The physicochemical properties of these lipids were characterised in the sodium salt form by monofilm experiments and X-ray powder diffraction. All lipids formed stable monofilms. The minimal space requirement of unsubstituted cardiolipin was dictated by the fatty acid pattern. Substitution with L-lysine led to a decrease of the molecular area, substitution with D-glucopyranosyl to an increase. On self assembly at 100% relative humidity, all preparations adopted lamellar structures. They showed a high degree of order, in spite of the heterogeneous fatty acid compositions and numerous fatty acid combinations. The repeat distances in lamellar fluid phase varied between 4.99 and 5. 52 nm, the bilayer thickness between 3.70 and 4.46 nm. Surprising were the low values of sorbed water per molecule of the glucosyl and lysyl derivatives which were 58 and 60%, compared with those of the respective cardiolipin. When Na(+) was replaced as counterion by Ba(2+), the bilayer structure was retained, but the lipids were in the lamellar gel phase and the fatty acids were tilted between 32 and 53 degrees away from the bilayer normal. Wide angle X-ray diffraction studies and electron density profiles are also reported. Particular properties of glucosyl cardiolipin are discussed.

Cardiolipins↗
PubMed1999

Polar lipids of four Listeria species containing L-lysylcardiolipin, a novel lipid structure, and other unique phospholipids.

The membrane lipids of Listeria innocua, Listeria monocytogenes, Listeria seeligeri and Listeria welshimeri were fractionated on DEAE-cellulose and purified by chromatography on silica gel and/or preparative TLC. The lipid structures were elucidated by chemical and chromatographic means. The polar lipid composition of the four listeria species was similar. Phospholipids predominated. They consisted of phosphatidylglycerol, L-lysylphosphatidylglycerol, cardiolipin [bis(phosphatidyl)glycerol] and L-lysylcardiolipin. A phospholipid more polar than cardiolipin, possibly two L-lysyl derivatives of it, sn-glycero-1-phosphoglycolipid, its D-alanyl derivative, and polyprenol phosphate were also detected. Towards the end of exponential growth, the relative amounts of cardiolipin and L-lysylcardiolipin increased, approaching 47-78% lipid phosphorus with a ratio of L-lysylcardiolipin to cardiolipin of 0.25-1.6. As shown by fast atom bombardment-mass spectrometry, cardiolipin and L-lysylcardiolipin consisted of five molecular species due to various fatty acid combinations. L-lysylcardiolipin has so far not been found in nature. It belongs to the recently discovered class of substituted cardiolipins. Its occurrence in the four listeria species tested shows that it is a characteristic lipid component of the L. monocytogenes line of descent. Further studies on the lipid pattern of members of the other descent line are required to decide whether lysylcardiolipin can serve as a genus-specific chemotaxonomic marker for listeriae.

Cardiolipins↗
PubMed1998

Uptake and incorporation of choline and ethanolamine into lipoteichoic acid and teichoic acid by the choline-independent mutant JY2190 of Streptococcus pneumoniae.

Lipoteichoic acid- and teichoic acid-containing muropeptides were isolated from choline- or ethanolamine-grown cells of the choline-independent mutant JY2190 of Streptococcus pneumoniae. Choline was taken up and incorporated into lipoteichoic acid and teichoic acid with 81% efficiency, compared with the parent strain Rx1. With similar efficiency, ethanolamine was incorporated. Accordingly, the mutant is a valuable tool for identifying the individual genes encoding the enzymes of choline utilisation, because any of these genes can be deleted without affecting viability and growth rate.

Choline↗
PubMed1998

The lantibiotic mersacidin inhibits peptidoglycan synthesis by targeting lipid II.

The lantibiotic mersacidin exerts its bactericidal action by inhibition of peptidoglycan biosynthesis. It interferes with the membrane-associated transglycosylation reaction; during this step the ultimate monomeric peptidoglycan precursor, undecaprenyl-pyrophosphoryl-MurNAc-(pentapeptide)-GlcNAc (lipid II) is converted into polymeric nascent peptidoglycan. In the present study we demonstrate that the molecular basis of this inhibition is the interaction of mersacidin with lipid II. The adsorption of [14C]mersacidin to growing cells, as well as to isolated membranes capable of in vitro peptidoglycan synthesis, was strictly dependent on the availability of lipid II, and antibiotic inhibitors of lipid II formation strongly interfered with this binding. Direct evidence for the interaction was provided by studies with isolated lipid II. [14C]mersacidin associated tightly with [14C]lipid II micelles; the complex was stable even in the presence of 1% sodium dodecyl sulfate. Furthermore, the addition of isolated lipid II to the culture broth efficiently antagonized the bactericidal activity of mersacidin. In contrast to the glycopeptide antibiotics, complex formation does not involve the C-terminal D-alanyl-D-alanine moiety of the lipid intermediate. Thus, the interaction of mersacidin with lipid II apparently occurs via a binding site which is not targeted by any antibiotic currently in use.

Anti-Bacterial Agents↗
PubMed1998

Generation and properties of a Streptococcus pneumoniae mutant which does not require choline or analogs for growth.

A mutant (JY2190) of Streptococcus pneumoniae Rx1 which had acquired the ability to grow in the absence of choline and analogs was isolated. Lipoteichoic acid (LTA) and wall teichoic acid (TA) isolated from the mutant were free of phosphocholine and other phosphorylated amino alcohols. Both polymers showed an unaltered chain structure and, in the case of LTA, an unchanged glycolipid anchor. The cell wall composition was also not altered except that, due to the lack of phosphocholine, the phosphate content of cell walls was half that of the parent strain. Isolated cell walls of the mutant were resistant to hydrolysis by pneumococcal autolysin (N-acetylmuramyl-L-alanine amidase) but were cleaved by the muramidases CPL and cellosyl. The lack of active autolysin in the mutant cells became apparent by impaired cell separation at the end of cell division and by resistance against stationary-phase and penicillin-induced lysis. As a result of the absence of choline in the LTA, pneumococcal surface protein A (PspA) was no longer retained on the cytoplasmic membrane. During growth in the presence of choline, which was incorporated as phosphocholine into LTA and TA, the mutant cells separated normally, did not release PspA, and became penicillin sensitive. However, even under these conditions, they did not lyse in the stationary phase, and they showed poor reactivity with antibody to phosphocholine and an increased release of C-polysaccharide from the cell. In contrast to ethanolamine-grown parent cells (A. Tomasz, Proc. Natl. Acad. Sci. USA 59:86-93, 1968), the choline-free mutant cells retained the capability to undergo genetic transformation but, compared to Rx1, with lower frequency and at an earlier stage of growth. The properties of the mutant could be transferred to the parent strain by DNA of the mutant.

Carbohydrate Sequence↗
PubMed1998

Interferon- and streptolysin O-induced activation of protein kinases and inhibition of cytochrome P450-dependent monooxygenases in rats.

Immunostimulants known to initiate cytokine production were found to decrease the activity of hepatic microsomal drug oxidative enzymes but to activate protein kinase C (PKC). The present study investigated the effects of immunostimulating doses of rat interferon-gamma (IFN, 670,000 units i.p.) and streptolysin O (SLO, 100 HU/kg i.v. for 5 days) on hepatic soluble, membrane-bound and nuclear PKC, 7-ethylresorufin-O-deethylase (EROD) and 7-pentylresorufin-O-deethylase (PROD) in male Wistar rats. The SLO- and IFN-mediated decrease of EROD and PROD activity was associated with a characteristic activation of the hepatic and spleenic PKC. In SLO- and IFN-treated animals activities of the cytosolic, membrane-bound and nuclear PKC were significantly higher than in respective controls. Our results suggest that a decrease in hepatic cytochrome P450 content as well as the decrease in the EROD and PROD activities are inversely related to the function of PKC.

Animals↗
PubMed1996

Microheterogeneity of the hydrophobic and hydrophilic part of the glycosylphosphatidylinositol anchor of alkaline phosphatase from calf intestine.

Digestion of calf intestine alkaline phosphatase with pronase and subsequent dephosphorylation of the released peptidyl-(Etn-P)2-glycosyl-PtdIns with HF generated 8 glycosyl-Ins species the largest of which (G1 and G2) have the following proposed structures: [sequence: see text] G3 and G5 are lower homologues of G1 and G2, respectively, being one alpha 1-2 linked mannopyranosyl residue shorter. G4 is analogous to G2 lacking the N-acetylgalactosaminyl residue and G6 is the next lower homologue of G4. Most of G4 and G6 occur substituted with a palmitoyl (G4, G6) or a myristoyl residue (G6) probably attached to the inositol moiety. Thus, the basic ManxGlc-Ins species are either substituted with an N-acetylgalactosaminyl residue or a fatty acid ester. The structures were deduced from compositional analysis, molecular-mass determination by matrix-assisted laser desorption MS, sequential hydrolysis with appropriate exoglycosidases and treatment with CrO3. Purification of the glycosylinositol species was achieved by a novel reverse-phase HPLC technique using fluorescent fluoren-9-yl-methoxy-carbonyl (Fmoc) derivatives. These stable derivatives were susceptible to hydrolysis with exoglycosidases which allowed sequential cleavages to be carried out and kinetics to be followed at the picomole level. We observed recently that native alkaline phosphatase separates on octyl-Sepharose into four distinct fractions of increasing hydrophobicity (F1-F4). Here we show that all four fractions contain G1-G6. The acylated species G4 and G6 were restricted to F2 and F4 which had been shown earlier to contain, on average, 2.5 and 3 fatty acid residues/subunit, respectively. In all four fractions the diradylglycerol moiety was predominantly diacylglycerol, alkylacylglycerol being less than 10% which is in contrast to most glycosyl-PtdIns--anchored proteins of mammalian origin.

Acetylgalactosamine↗
PubMed1996

Outer Membrane Protein Heterogeneity within Pseudomonas fluorescens and P. putida and Use of an OprF Antibody as a Probe for rRNA Homology Group I Pseudomonads.

The electrophoretic patterns of outer membrane proteins of strains representing the biovars of Pseudomonas fluorescens and Pseudomonas putida were analyzed by gel electrophoresis. The outer membrane protein profiles were variable, and they were not useful for assigning strains to a specific biovar. However, three or four predominant outer membrane proteins migrating at 42 to 46 kDa, 33 to 38 kDa, and 20 to 22 kDa were conserved among the strains. They could be tentatively identified as OprE (44 kDa), OprF (38 kDa), OprH (21 kDa), and OprL (20.5 kDa), which are known proteins from Pseudomonas aeruginosa. A 37-kDa OprF-like protein was purified from P. fluorescens DF57 and used to raise a polyclonal antibody. In Western blot (immunoblot) analysis, this antibody reacted with OprF proteins from members of Pseudomonas rRNA homology group I but not with proteins from nonpseudomonads. The heterogeneity in M(infr) of OprF was greater among P. fluorescens strains than among P. putida strains. Immunofluorescence microscopy of intact cells demonstrated that the antibody recognized epitopes that were accessible only after unmasking by EDTA treatment. The antibody was used in a colony blotting assay to determine the percentage of rRNA homology group I pseudomonads among bacteria from the rhizosphere of barley. The bacteria were isolated on 10% tryptic soy agar, King's B agar, and the pseudomonad-specific medium Gould S1 agar. The estimate of OprF-containing CFU in rhizosphere soil obtained by colony blotting on 10% tryptic soy agar was about 2 and 14 times higher than the values obtained from King's agar and Gould S1 agar, respectively, indicating that not all fluorescent pseudomonads are scored on more specific media. The colonies reacting with the OprF antibody were verified as being rRNA homology group I pseudomonads by using the API 20NE system.

Journal Article↗
PubMed1996

The intercellular adhesin involved in biofilm accumulation of Staphylococcus epidermidis is a linear beta-1,6-linked glucosaminoglycan: purification and structural analysis.

The primary attachment to polymer surfaces followed by accumulation in multilayered cell clusters leads to biofilm production of Staphylococcus epidermidis, which is thought to contribute to virulence in biomaterial-related infections. We purified a specific polysaccharide antigen of biofilm-producing S. epidermidis 1457 and RP62A, which was recently shown to have a function in the accumulative phase of biofilm production by mediating intercellular adhesion (D. Mack, M. Nedelmann, A. Krokotsch, A. Schwarzkopf, J. Heesemann, and R. Laufs, Infect. Immun. 62:3244-3253, 1994). Following Sephadex G-200 gel filtration, this antigen was separated by Q-Sepharose chromatography into a major polysaccharide, polysaccharide I (> 80%), which did not bind to Q-Sepharose, and a minor polysaccharide, polysaccharide II (< 20%), which was moderately anionic. As shown by chemical analyses and nuclear magnetic resonance spectroscopy, polysaccharide I is a linear homoglycan of at least 130 beta-1,6-linked 2-deoxy-2-amino-D-glucopyranosyl residues. On average, 80 to 85% of them are N acetylated; the rest are non-N-acetylating and positively charged. Chain cleavage by deamination with HNO2 revealed a more or less random distribution of the non-N-acetylated glucosaminyl residues, with some prevalence of glucosaminyl-rich sequences. Cation-exchange chromatography separated molecular species whose content of non-N-acetylated glucosaminyl residues varied between 2 and 26%. Polysaccharide II is structurally related to polysaccharide I but has a lower content of non-N-acetylated D-glucosaminyl residues and contains phosphate and ester-linked succinate, rendering it anionic. Enzyme-linked immunosorbent assay inhibition with various monosaccharides revealed the beta-anomeric form and the acetylated amino group of the D-glucosaminyl residues as important for reactivity with the specific antiserum. The unbranched polysaccharide structure favors long-range contacts and interactions between polysaccharide strands and the cell wall and/or lectin-like proteins, leading to intercellular adhesion and biofilm accumulation. The structure of the polysaccharide is, so far, considered to be unique and, according to its function, is referred to as S. epidermidis polysaccharide intercellular adhesin (PIA).

Acetylglucosamine↗
PubMed1995

Incorporation of D-alanine into lipoteichoic acid and wall teichoic acid in Bacillus subtilis. Identification of genes and regulation.

The Bacillus subtilis dlt operon (D-alanyl-lipoteichoic acid) is responsible for D-alanine esterification of both lipoteichoic acid (LTA) and wall teichoic acid (WTA). The dlt operon contains five genes, dltA-dltE. Insertional inactivation of dltA-dltD results in complete absence of D-alanine from both LTA and WTA. Based on protein sequence similarity with the Lactobacillus casei dlt gene products (Heaton, M. P., and Neuhaus, F. C. (1992) J. Bacteriol. 174, 4707-4717), we propose that dltA encodes the D-alanine-D-alanyl carrier protein ligase (Dcl) and dltC the D-alanyl carrier protein (Dcp). We further hypothesize that the products of dltB and dltD are concerned with the transport of activated D-alanine through the membrane and the final incorporation of D-alanine into LTA. The hydropathy profiles of the dltB and dltD gene products suggest a transmembrane location for the former and an amino-terminal signal peptide for the latter. The incorporation of D-alanine into LTA and WTA did not separate in any of the mutants studied which indicates that either one and the same enzyme is responsible for D-alanine incorporation into both polymers or a separate enzyme, encoded outside the dlt operon, transfers the D-alanyl residues from LTA to WTA (Haas, R., Koch, H.-U., and Fischer, W. (1984) FEMS Microbiol. Lett. 21, 27-31). Inactivation of dltE has no effect on D-alanine ester content of both LTA and WTA, and at present we cannot propose any function for its gene product. Transcription analysis shows that the dlt operon is transcribed from a sigma D-dependent promoter and follows the pattern of transcription of genes belonging to the sigma D regulon. However, the turn off of transcription observed before sporulation starts seems to be dependent on the Spo0A and AbrB sporulation proteins and results in a D-alanine-free purely anionic LTA in the spore membrane. The dlt operon is dispensable for cell growth; its inactivation does not affect cell growth or morphology as described for L. casei.

Alanine↗
PubMed1994

Phase II study of neoadjuvant chemotherapy and radiation therapy with thoracotomy in the treatment of clinically staged IIIA non-small cell lung cancer.

BACKGROUND: The purpose of this study was to assess the ability of administering to patients induction chemotherapy with carboplatin and etoposide (VP-16), followed by full-course radiation therapy and weekly carboplatin with tolerable toxicity as preoperative therapy to down-stage disease thus allowing the resection of clinically staged IIIA non-small cell lung cancer. METHODS: Twenty-eight eligible patients with good performance status and previously untreated, marginally resectable stage IIIA non-small cell lung cancer received induction chemotherapy with carboplatin (dosed per the Egorin formulation), and VP-16 (100 mg/m2) followed by 6000 cGy of chest radiotherapy over six weeks administered concurrently with weekly doses of 100 mg/m2 of carboplatin. Patients who had either responsive or stable disease underwent thoracotomy, with attempted surgical resection of the primary lung lesion and the areas of abnormal adenopathy. Procedures involving less than a pneumonectomy were used whenever feasible. RESULTS: Fifty-two cycles of induction chemotherapy were administered. The average initial dose of carboplatin was 407 mg/m2. Toxicity was tolerable with grade 3-4 neutropenia and/or thrombocytopenia in 48 and 27% of the patients. There were no septic deaths. Full-dose radiotherapy was administered to 82% of patients, with 73% receiving at least five weekly doses of carboplatin. The radiographically assessed response rate to the neoadjuvant treatment was 64% (partial response, 46%; minimal response, 18%). Sixteen patients underwent gross tumor resection with 12 (43%) having negative pathologic margins. Six patients had pneumonectomy. There were three perioperative deaths (19%); two were secondary to respiratory failure after the patients underwent a pneumonectomy. The median survival for all 28 patients was 15 months, and for the 16 patients undergoing thoracotomy was 23 months. Eight patients were alive and in remission, with follow-up ranging from 8 to 31 months. CONCLUSIONS: The authors conclude that (1) carboplatin and VP-16, followed by full-dose radiotherapy with weekly carboplatin administration, is a well tolerated and effective regimen in the treatment of patients with marginally resectable stage IIIA non-small cell lung cancer; and (2) full-course radiotherapy can be administered before surgical resection without additional surgical morbidity or mortality.

Adult↗
PubMed1993

Isomalto-oligosaccharide-containing lipoteichoic acid of Streptococcus sanguis. Microheterogeneity and distribution of chain substituents.

The lipoteichoic acid of Streptococcus sanguis DSM 20567 contains a poly(glycerophosphate) chain, with 49% of the glycerophosphate residues being substituted with D-alanine ester, 35% with alpha-D-glucopyranosyl and alpha-isomalto-oligosaccharide residues. Analysis of molecular species by affinity chromatography on concanavalin A showed all chains to be substituted and alanine ester and glycosyl residues to be present on the same rather than on separate chains. Molecular species varied in the length of the poly(glycerophosphate) chain, the extent of glycosylation, and had a constant alanine-ester content. An alkali-hydrolysis procedure revealed a distribution pattern between random and regular for the glycosyl substituents and suggested a similar distribution for the alanyl residues which occupy the free positions between the glycosyl substituents.

Chromatography, Affinity↗
PubMed1993

Molecular analysis of the lipoglycans of Mycobacterium tuberculosis.

Lipoglycans were extracted from disrupted cells of Mycobacterium tuberculosis with hot phenol-water. Hydrophobic interaction chromatography on octyl-Sepharose of the crude extract separated nucleic acids and lipoglycans. The latter were retained on the column and fractionated on elution with a propanol gradient into six peaks primarily according to decreasing size of the hydrophilic head groups which dropped from 70 to 5 or 4 monosaccharide residues per molecule. The number of fatty acids per molecule rose from 2.1 to 3.4 over the elution profile, suggesting species containing two, three, and four fatty acids. Peaks I and II and peaks III and IV represented two pairs of lipoarabinomannan and lipomannan, those of peak III and IV containing as a whole smaller hydrophilic head groups and more fatty acids. Peak V and VI are reminiscent of the oligomannosyl derivatives of phosphatidylinositol discovered earlier in mycobacteria. The lipid anchor of all molecular species was shown to be phosphatidylinositol with the extra acyl groups not yet localized. This and an accompanying report complement each other in demonstrating the potential of hydrophobic interaction chromatography for molecular analysis of lipid macroamphiphiles. Lipoteichoic acids, due to continuous small variations in the size of their hydrophilic head groups, separate primarily according to the number of fatty acids, whereas mycobacterial lipoarabinomannans, lipomannans, and phosphatidylinositol mannosides differ as entities so greatly in the size of the hydrophilic headgroup that this quality becomes predominant for separation.

Chromatography, Agarose↗
PubMed1992

Endobronchial interstitial Au-198 implantation in the treatment of recurrent bronchogenic carcinoma.

Nineteen patients with non-small-cell bronchogenic carcinoma, recurrent following initial conventional external beam radiotherapy, were treated with endobronchial implantation of Au-198 seeds. Seventeen patients were symptomatic with primary symptoms of persistent hemoptysis (9), bronchial obstruction (2), or worsening dyspnea (6). Two patients were asymptomatic and implanted for bronchoscopic evidence of tumor recurrence. The dose delivered was described by three dosimetric parameters: 1) the total activity implanted (m Ci); 2) the midbronchial dose point; and 3) the volume of tissue that received greater than 20 Gy. Response was determined based on a system reflecting the primary indication for the implant. Seven of nine (78%) presenting with hemoptysis, four of six (67%) with increasing dyspnea, and one of two with bronchial obstruction responded. The overall median survival was 5.25 months (2.5-10 months 95% confidence interval). There was no clear correlation between any of the dosimetric parameters evaluated and a clinical response to therapy. Technical complications related to the inability to penetrate the scirrhous tumor surface adequately often led to less than optimal dose distribution. Endobronchial Au-198 implantation is associated with a poor calculated dose distribution but is, nonetheless, a relatively simple and comparatively inexpensive technique that often produces a clinical response and can be a useful option in the management of patients with recurrent bronchogenic carcinoma.

Adult↗