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V Müller

Publications and source records attributed to V Müller.

At least 19 recordsLinked to original sources
PubMed1992

Presence of a sodium-translocating ATPase in membrane vesicles of the homoacetogenic bacterium Acetobacterium woodii.

Inverted membrane vesicles of the homoacetogenic bacterium Acetobacterium woodii catalyzed the hydrolysis of ATP with a rate of 100-150 nmol.min-1.mg protein-1. The ATPase was stimulated 1.4-1.6-fold by NaCl and inhibited by N,N'-dicyclohexylcarbodiimide tributyltin or azide. The degree of inhibition caused by F0-directed but not F1-directed inhibitors was affected by the Na+ concentration in the medium. These experiments indicated the presence of a sodium-translocating ATPase. This was verified by transport studies. Upon addition of ATP to inverted vesicles, 22Na+ was actively transported into the intravesicular space up to a 24-fold accumulation. Na+ transport was inhibited by the sodium ionophore N,N,N',N',-tetracyclohexyl-1,2-phenyl-enedioxydiacetamide but stimulated by valinomycin with potassium whereas the protonophore 3,5,-di-tert-butyl-4-hydroxybenzylidenemalonitrile was without effect. N,N'-dicyclohexylcarbodiimide and tributyltin inhibited 22Na+ transport. These experiments are in accordance with a primary electrogenic Na+ transport as catalyzed by a F1F0-ATPase.

Adenosine Triphosphatases↗
PubMed1992

Energetics of methanogenesis studied in vesicular systems.

Methanogenesis is restricted to a group of prokaryotic microorganisms which thrive in strictly anaerobic habitats where they play an indispensable role in the anaerobic food chain. Methanogenic bacteria possess a number of unique cofactors and coenzymes that play an important role in their specialized metabolism. Methanogenesis from a number of simple substrates such as H2 + CO2, formate, methanol, methylamines, and acetate is associated with the generation of transmembrane electrochemical gradients of protons and sodium ions which serve as driving force for a number of processes such as the synthesis of ATP via an ATP synthase, reverse electron transfer, and solute uptake. Several unique reactions of the methanogenic pathways have been identified that are involved in energy transduction. Their role and importance for the methanogenic metabolism are described.

Adenosine Triphosphate↗
PubMed1992

Subdivision of flagellar region III of the Escherichia coli and Salmonella typhimurium chromosomes and identification of two additional flagellar genes.

The many genes involved in flagellar structure and function in Escherichia coli and Salmonella typhimurium are located in three major clusters on the chromosome: flagellar regions I, II and III. We have found that region III does not consist of a contiguous set of flagellar genes, as was thought, but that in E. coli there is almost 7 kb of DNA between the filament cap gene, fliD, and the next known flagellar gene, fliE; a similar situation occurs in S. typhimurium. Most of this DNA is unrelated to flagellar function, since a mutant in which 5.4 kb of it had been deleted remained fully motile and chemotactic as judged by swarming on semi-solid agar. We have therefore subdivided flagellar region III into two regions, IIIa and IIIb. The known genes in region IIIa are fliABCD, all of which are involved in filament structure and assembly, while region IIIb contains genes fliEFGHIJKLMNOPQR, all of which are related to formation of the hook (basal-body)-complex or to even earlier assembly events. We have found that fliD, the last known gene in region IIIa, is immediately followed by two additional genes, both necessary for flagellation, which we have designated fliS and fliT. They encode small proteins with deduced molecular masses of about 15 kDa and 14 kDa, respectively. The functions of FliS and FliT remain to be determined, but they do not appear to be members of the axial family of structural proteins to which FliD belongs.

Amino Acid Sequence↗
PubMed1992

Escherichia coli produces a cytoplasmic alpha-amylase, AmyA.

In the gap between two closely linked flagellar gene clusters on the Escherichia coli and Salmonella typhimurium chromosomes (at about 42 to 43 min on the E. coli map), we found an open reading frame whose sequence suggested that it encoded an alpha-amylase; the deduced amino acid sequences in the two species were 87% identical. The strongest similarities to other alpha-amylases were to the excreted liquefying alpha-amylases of bacilli, with > 40% amino acid identity; the N-terminal sequence of the mature bacillar protein (after signal peptide cleavage) aligned with the N-terminal sequence of the E. coli or S. typhimurium protein (without assuming signal peptide cleavage). Minicell experiments identified the product of the E. coli gene as a 56-kDa protein, in agreement with the size predicted from the sequence. The protein was retained by spheroplasts rather than being released with the periplasmic fraction; cells transformed with plasmids containing the gene did not digest extracellular starch unless they were lysed; and the protein, when overproduced, was found in the soluble fraction. We conclude that the protein is cytoplasmic, as predicted by its sequence. The purified protein rapidly digested amylose, starch, amylopectin, and maltodextrins of size G6 or larger; it also digested glycogen, but much more slowly. It was specific for the alpha-anomeric linkage, being unable to digest cellulose. The principal products of starch digestion included maltotriose and maltotetraose as well as maltose, verifying that the protein was an alpha-amylase rather than a beta-amylase. The newly discovered gene has been named amyA. The natural physiological role of the AmyA protein is not yet evident.

Amino Acid Sequence↗
PubMed1992

N5-methyl-tetrahydromethanopterin:coenzyme M methyltransferase of Methanosarcina strain Gö1 is an Na(+)-translocating membrane protein.

To determine the cellular localization of components of the methyltransferase system, we separated cell extracts of Methanosarcina strain Gö1 into cytoplasmic and inverted-vesicle fractions. Measurements demonstrated that 83% of the methylene-tetrahydromethanopterin reductase activity resided in the cytoplasm whereas 88% of the methyl-tetrahydromethanopterin:coenzyme M methyltransferase (methyltransferase) was associated with the vesicles. The activity of the methyltransferase was stimulated 4.6-fold by ATP and 10-fold by ATP plus a reducing agent [e.g., Ti(III)]. In addition, methyltransferase activity depended on the presence of Na+ (apparent Km = 0.7 mM) and Na+ was pumped into the lumen of the vesicles in the course of methyl transfer from methyl-tetrahydromethanopterin not only to coenzyme M but also to hydroxycobalamin. Both methyl transfer reactions were inhibited by 1-iodopropane and reconstituted by illumination. A model for the methyl transfer reactions is presented.

Carrier Proteins↗
PubMed1992

Characterization of the fliE genes of Escherichia coli and Salmonella typhimurium and identification of the FliE protein as a component of the flagellar hook-basal body complex.

Within flagellar region III of Escherichia coli and Salmonella typhimurium, the genomic organization has been largely established. An exception is fliE, a gene whose exact location and product function are not well understood. We cloned the fliE gene, obtained its DNA sequence, and identified its product.fliE was found to be a monocistronic transcriptional unit, adjacent to and divergent from the large fliF operon. It is several kilobases distant from the nearest flagellar operon in the other direction, the fliD operon, and constitutes the first operon within the newly defined region IIIb, which contains the genes fliE through fliR.fliE encodes a small, moderately hydrophilic protein with a deduced molecular mass of 11,114 Da (E. coli) or 11,065 Da (S. typhimurium). We identified a protein within the isolated hook-basal body complex as the fliE gene product on the basis of its size and comparison of its N-terminal amino acid sequence with that deduced from the gene sequence. From gel electrophoresis and autoradiography of 35S-labeled S. typhimurium hook-basal body complexes (C.J. Jones, R.M. Macnab, H. Okino, and S.-I. Aizawa, J. Mol. Biol. 212:377-387, 1990) and the deduced number of sulfur-containing residues in FliE, we estimated the stoichiometry of the protein in the hook-basal body complex to be about nine subunits. FliE does not undergo cleavage of a signal peptide, nor does it show any sequence similarity to the axial components like the rod or hook proteins, which are believed to be exported by the flagellum-specific export pathway. On the basis of this and other evidence, we suggest that FliE may be in the vicinity of the MS ring, perhaps acting as an adaptor protein between the ring and rod substructures.

Amino Acid Sequence↗
PubMed1992

[Therapeutic control of premedication with famotidine given on the evening before surgery for the prevention of pneumonitis in heart surgery patients].

Pulmonary damage after aspiration of acid gastric content is one of the major risks of general anaesthesia. Antisecretory therapy with different H2-antagonists can effectively decrease the risk of aspiration. The effective dosage and the method and timing of administration remain unclear. PATIENTS AND METHODS. A series of 38 patients scheduled for elective cardiac surgery (coronary artery bypass graft) were premedicated at random at 10:00 p.m. on the evening prior to surgery with famotidine 40 mg and flunitrazepam 0.5 mg p.o. or with flunitrazepam alone. Continuous intragastric pH monitoring (720 values/h) with a combined glass electrode was started immediately after induction and continued for at least 12 h after surgery, in most cases up to extubation. The time periods analyzed were the first 30 min after induction, time of surgery, 12 h after surgery, and time of extubation. For each period the number of pH values less than 2.5 and pH less than 4, mean and median, and significance of differences were calculated. STATISTICS. Test statistics were evaluated using the Wilcoxon test and the Mann-Whitney U-test. RESULTS. (see Table 1, Fig. 1). The mean time interval between oral premedication and induction of anaesthesia was 9.7 h. There were no differences between the groups concerning age and duration of surgery. The average age was 51 in the group of treated patients (n = 15) and 59 years in the control group (n = 23). The average duration of surgery was 3.36 h and 4.02 h. During induction and in the following 30 min, in the famotidine treatment group 28.7% of all pH values were pH less than 2.5, as against 45.4% in the control group (P = 0.08). Intraoperative values: 16.3% pH less than 2.5 against 24.7% (not significant); 12 h postoperative: 21.1% vs 17.8% and during extubation 40% vs 21% (not significant). During induction there were more pH values less than 2.5 in the control than in the treatment group (P = 0.08). Treated patients had nearly 30% pH values less than 2.5 and therefore, a persisting risk of acid aspiration. In both groups intragastric acidity decreased during surgery. Postoperatively there was no difference between the two groups, and during extubation more patients in the famotidine-treated group had values below pH 2.5. CONCLUSION. Prophylaxis of acid aspiration before, during and after cardiac surgery can be achieved by increasing the pH of the gastric content. The timing and the method of administration must be selected to a safe decrease in intragastric acidity before the induction of general anaesthesia. Famotidine 40 mg given orally at 10.00 p.m. on the evening before surgery is not a reliable means of decreasing intragastric acidity or, consequently, of preventing of acid aspiration syndrome.

Administration, Oral↗
PubMed1991

A sodium-stimulated ATP synthase in the acetogenic bacterium Acetobacterium woodii.

Experiments with resting cells of Acetobacterium woodii were performed to elucidate the coupling ion used by the ATP synthase. A. woodii synthesized ATP in response to an artificial delta pH, indicating the presence of a proton-translocating ATPase. On the other hand, a delta pNa, as well as a proton diffusion potential, could serve as a driving force for ATP synthesis with the latter strictly dependent on Na+. These results are indicative for the presence of a Na(+)-translocating ATP synthase in A. woodii.

Gram-Positive Rods↗
PubMed1991

Clonal deletion of V beta 14-bearing T cells in mice transgenic for mammary tumour virus.

Autoreactive T lymphocytes are clonally deleted during maturation in the thymus. Deletion of T cells expressing particular receptor V beta elements is controlled by poorly defined autosomal dominant genes. A gene has now been identified by expression of transgenes in mice which causes deletion of V beta 14+ T cells. The gene lies in the open reading frame of the long terminal repeat of the mouse mammary tumour virus.

Amino Acid Sequence↗
PubMed1991

Pharmacokinetics of ampicillin and sulbactam in patients undergoing heart surgery.

The pharmacokinetics of ampicillin and sulbactam, a new beta-lactamase inhibitor, were investigated in 16 patients undergoing prosthetic cardiac valve insertion. The combination of 2 g of ampicillin and 1 g of sulbactam was administered as perioperative prophylaxis intravenously over 3 to 6 days. Several serum pharmacokinetic parameters were similar for the two drugs after three intravenous doses were given to patients following surgery. The half-lives of elimination of ampicillin and sulbactam were 79 +/- 4.9 and 88 +/- 5.9 min, the volumes of distribution were 15.6 +/- 1.4 and 17.7 +/- 1.2 liters/70 kg, and the total plasma clearances were 144.4 +/- 14.5 and 147.2 +/- 14.5 ml/min, respectively. The peak concentrations of ampicillin and sulbactam in serum were calculated to be 134.3 +/- 1.3 and 58.3 +/- 1.2 micrograms/ml, respectively. Ampicillin and sulbactam rapidly penetrated from the blood into various tissues collected during heart surgery, such as sternum, pericardium, myocardium, and endocardium. The concentrations of ampicillin in tissue ranged from 17.8 +/- 9.9 to 50 +/- 29.5 micrograms/g, and those of sulbactam in tissue ranged from 8.8 +/- 6.2 to 19.6 +/- 10.1 micrograms/g. The concentrations of ampicillin and sulbactam in serum and tissue also apparently exceeded the MICs against most beta-lactamase-producing bacteria usually involved in postoperative wound infections and prosthetic valve endocarditis. The ratio of the two compounds was approximately 2:1 in serum and in the various tissues affected by the operation. The pharmacokinetics of ampicillin and sulbactam in serum and investigated tissues suggest that the combination of the two beta-lactams will be effective in the perioperative prophylaxis of patients undergoing heart surgery.

Aged↗
PubMed1989

[THe effect of pregnancy on the long-term course of chronic glomerulonephritis].

During a long-term study in 34 out of 154 women with bioptically ascertained glomerulonephritis 38 pregnancies were observed. The clinical manifestation took place three times during and thirteen times immediately after the end of the pregnancy. Apart from membranoproliferative glomerulonephritides all morphological forms of glomerulonephritis were present. A nephrotic syndrome was existing in 14 women (41.2%). The patients with pregnancy after on an average 11.3 years observation time showed a stabile renal function in 85.3% in contrast to 71.9% of the other female patients (not significant). The pregnancy, including a nephrotic syndrome, does not deteriorate the long-term prognosis of the glomerulonephritis.

Biopsy↗
PubMed1989

Sodium dependence of acetate formation by the acetogenic bacterium Acetobacterium woodii.

Growth of Acetobacterium woodii on fructose was stimulated by Na+; this stimulation was paralleled by a shift of the acetate-fructose ratio from 2.1 to 2.7. Growth on H2-CO2 or on methanol plus CO2 was strictly dependent on the presence of sodium ions in the medium. Acetate formation from formaldehyde plus H2-CO by resting cells required Na+, but from methanol plus H2-CO did not. This is analogous to H2-CO2 reduction to methane by Methanosarcina barkeri, which involves a sodium pump (V. Müller, C. Winner, and G. Gottschalk, Eur. J. Biochem. 178:519-525, 1988). This suggests that the reduction of methylenetetrahydrofolate to methyltetrahydrofolate is the Na+-requiring reaction. A sodium gradient (Na+ out/Na+ in = 32, delta pNa = -91 mV) was built up when resting cells of A. woodii were incubated under H2-CO2. Acetogenesis was inhibited when the delta pNa was dissipated by monensin.

Acetates↗
PubMed1989

[Differentiation of hematuria by phase contrast microscopy studies of urine erythrocytes].

The results of phase-contrast microscopic investigations of urinary erythrocytes in 300 patients (120 patients with bioptical verified glomerulonephritis, 54 patients suffering from interstitial nephritis, 56 patients with urinary tract diseases and 70 healthy probands) are discussed. The portion of glomerular erythrocytes is dependent on diuresis, renal function and activity of glomerulonephritis. This non-invasive procedure is quick and easy practicable and its results are reliable (sensitivity and specifity of more than 90%). The proof of mainly glomerular erythrocytes save from instrumental and invasive diagnostic procedures in nephrological diseases, whereas non-glomerular erythrocytes may have an urological or hematological origin.

Adolescent↗
PubMed1988

Electron-transport-driven sodium extrusion during methanogenesis from formaldehyde and molecular hydrogen by Methanosarcina barkeri.

Methanogenesis from formaldehyde or formaldehyde + H2, as carried out by Methanosarcina barkeri, was strictly dependent on sodium ions whereas methane formation from methanol + H2 or methanol + formaldehyde was Na+-independent. This indicates that the reduction of formaldehyde to the formal redox level of methanol exhibits a Na+ requirement. During methanogenesis from formaldehyde, a delta pNa in the range of -62 mV to -80 mV was generated by means of a primary, electron-transport-driven sodium pump. This could be concluded from the following results obtained on cell suspensions of M. barkeri. 1. The addition of proton conductors or inhibitors of the Na+/H+ antiporter had no effect on sodium extrusion. 2. During methanogenesis from formaldehyde + H2 a delta psi of -60 mV to -70 mV was generated even in the presence of proton conductors. 3. ATPase inhibitors, applied in the presence of proton conductors, had no effect on primary sodium extrusion or generation of a delta psi. Evidence for a Na+-translocating ATPase could not be obtained.

Adenosine Triphosphate↗
PubMed1988

The transmembrane electrochemical gradient of Na+ as driving force for methanol oxidation in Methanosarcina barkeri.

A sodium ion gradient (inside low) across the cytoplasmic membrane of Methanosarcina barkeri was required for methanogenesis from methanol. This could be concluded from the following results. (a) Inhibition of the Na+/H+ antiporter by K+ or amiloride led to an inhibition of methanogenesis from methanol. (b) Upon addition of the sodium ionophore monensin the Na+ gradient was abolished and at the same time methanogenesis from methanol was inhibited. (c) Methanogenesis was impaired when the Na+ gradient had the opposite orientation (inside high). All these inhibitory effects were not observed when H2 was present in addition to methanol indicating that the oxidation of methanol to CO2 was driven by a sodium-motive force. In accordance with this, a methanol-dependent influx of Na+ and a corresponding decrease of the membrane potential could be observed, when the Na+/H+ antiporter was inhibited by amiloride. This influx was indicative of the presence of a Na+ transport system which was functional when the oxidation of methanol had to be driven, but was not functional when H2 was present for reduction of methanol to methane.

Amiloride↗