Biomedical subjects

V Müller

Publications and source records attributed to V Müller.

At least 109 records · Page 6Linked to original sources

PubMed1994

Purification of ATP synthase from Acetobacterium woodii and identification as a Na(+)-translocating F1F0-type enzyme.

The ATPase of Acetobacterium woodii was purified after solubilization of membranes with Triton X-100 by poly(ethylene glycol) precipitation and gel filtration. The enzyme consists of at least six subunits of apparent molecular masses of 57, 52, 35, 19, 15 and 4.8 kDa, as determined by SDS/PAGE. The 52-kDa band is immunologically related to the F1F0-ATPase beta subunit of Escherichia coli. The enzyme is not inhibited by vanadate but is inhibited by nitrate, azide and N,N'-dicyclohexylcarbodiimide; the 4.8-kDa subunit specifically reacts with N,N'-dicyclohexyl[14C]carbodiimide, indicating that the enzyme is of the F1F0 type. The enzyme activity is dependent on MgATP (Km = 0.4), has a pH optimum of pH 7-9 and is stimulated by sulfite. ATP hydrolysis is strictly dependent on sodium ions with a Km for Na+ of 0.4 mM. The purified enzyme was reconstituted into liposomes. Upon addition of ATP, primary and electrogenic 22Na+ transport into the lumen of the proteoliposomes was determined. These experiments demonstrate that the ATPase of Acetobacterium woodii is a Na(+)-translocating F1F0-type ATPase.

Amino Acid Sequence↗

PubMed1994

Delta mu Na+ drives the synthesis of ATP via an delta mu Na(+)-translocating F1F0-ATP synthase in membrane vesicles of the archaeon Methanosarcina mazei Gö1.

Methanosarcina mazei Gö1 couples the methyl transfer from methyl-tetrahydromethanopterin to 2-mercaptoethanesulfonate (coenzyme M) with the generation of an electrochemical sodium ion gradient (delta mu Na+) and the reduction of the heterodisulfide of coenzyme M and 7-mercaptoheptanoylthreoninephosphate with the generation of an electrochemical proton gradient (delta muH+). Experiments with washed inverted vesicles were performed to investigate whether both ion gradients are used directly for the synthesis of ATP. delta mu Na+ and delta mu H+ were both able to drive the synthesis of ATP in the vesicular system. ATP synthesis driven by heterodisulfide reduction (delta mu H+) or an artificial delta pH was inhibited by the protonophore SF6847 but not by the sodium ionophore ETH157, whereas ETH157 but not SF6847 inhibited ATP synthesis driven by a chemical sodium ion gradient (delta pNa) as well as the methyl transfer reaction (delta mu Na+). Inhibition of the Na+/H+ antiporter led to a stimulation of ATP synthesis driven by the methyl transfer reaction (delta mu Na+), as well as by delta pNa. These experiments indicate that delta mu Na+ and delta mu H+ drive the synthesis of ATP via an Na(+)- and an H(+)-translocating ATP synthase, respectively. Inhibitor studies were performed to elucidate the nature of the ATP synthase(s) involved. delta pH-driven ATP synthesis was specifically inhibited by bafilomycin A1, whereas delta pNa-driven ATP synthesis was exclusively inhibited by 7-chloro-4-nitro-2-oxa-1,3-diazole, azide, and venturicidin. These results are evidence for the presence of an F(1)F(0)-ATP synthase in addition to the A(1)A(0)-ATP synthase in membranes of M. Mazei Gö1 and suggest that the F(1)F(0)-type enzyme is an Na+-translocating ATP synthase, whereas the A(1)A(0)-ATP synthase uses H+ as the coupling ion.

Acetamides↗

PubMed1994

[Trichobilharzia franki n. sp.--the cause of swimmer's dermatitis in southwest German dredged lakes].

Ocellate furcocercariae from the lymnaeid snail Radix auricularia have been identified as causative agents of swimmer's itch, which has become increasingly common in the 'Tunisee' near Freiburg. On an average 11.0%, maximally 25.0%, of the snails were parasitized with these trematode larvae. The Trichobilharzia parasitizing rate in the intermediate hosts found here was thus approximately 10-100 times higher than the Trichobilharzia prevalence described so far. Dwarf mallards (Anas platyrhynchos, blood red) were experimentally infected with Trichobilharzia cercariae from the 'Tunisee'. From the 13th day p.i. miracidia could be found in their faeces by means of the hatching method. The trematode eggs had the shape of an elongated spindle, with a pointed and a rounded end. The sexually differentiated adult worms were localized only in the hepatic and enteric veins. They had an average length of 4.0 mm (3.2-4.6 mm) and a width of 125 microns. Their tegument was strongly folded and had tegumental spines in the oral and ventral suckers, in males in addition along the canalis gynaecophorus. The most striking internal organ was the gut filled with hematin and separated in 2 caeca at its anterior end. Its form and localisation as well as those of the sexual organs were important criteria for the differentiation of the different Trichobilharzia species. The Trichobilharzia species found in the 'Tunisee' clearly differed from Trichobilharzia szidati both morphologically and physiologically. The latter has been considered, until now, to be the main causative agent of swimmer's itch in Germany. Moreover, the adult trematodes from the 'Tunisee' could not be associated with any other species of this genus. We propose therefore the name Trichobilharzia franki n. sp. for the species from the Tunisee.

Animals↗

PubMed1993

[The effect of praziquantel on Trichobilharzia (Digenea, Schistosomatidae), a cause of swimmer's dermatitis in humans].

Cases of swimmer's itch caused by cercariae of the genus Trichobilharzia have spread during the last years in Southwestern Germany and increased in intensity. The only consequence was to forbid swimming because no effective strategies are known which would be ecologically or financially acceptable. In this examination we therefore tried, by means of medication of ducks, the possible final hosts, to kill the different stages of Trichobilharzia in patency and prepatency in order to interrupt the parasitic cycle. For this the effectiveness of praziquantel on the parasitic stages in the final host (preadults, adults, eggs or fully developed miracidia) was tested in experimentally infected dwarf mallards (Anas platyrhynchos, hemerot.) and mallards (Anas platyrhynchos platyrhynchos). During therapy of ducks with patent Trichobilharzia infection, onefold or twofold application of this drug (1 x 500 mg/duck, 1 x 300 mg/duck, 2 x 200 mg/duck) only prevented the releasing of eggs with hatchable miracidia for up to 24 h. Only a threefold application of 200 mg/duck in 24 h intervals led to a permanent reduction of detectable miracidia. Application of praziquantel in low doses (30 or 40 mg per duck and day) did not reduce the number of released miracidia. Medication with praziquantel led to a strong shift of adult worms located in the enteric veins of the ducks to the liver veins in a little as 3 h; examinations by scanning electron microscopy revealed changes in the worms' surface and damage of the tegument. During prepatency doses of 22.5 mg praziquantel per duck and day, given continuously for one week, were sufficient to completely stop the release of miracidia. In this low dosage, a special preparation of the bitter drug was voluntarily swallowed by the ducks, thus providing in principal a simple, cheap and ecologically sound method of controlling cercarial dermatitis.

Administration, Oral↗

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