Search PubMed⌕ Search

Biomedical subjects

T Krafft

Publications and source records attributed to T Krafft.

16 recordsLinked to original sources
PubMed1995

The function of Wolinella succinogenes psr genes in electron transport with polysulphide as the terminal electron acceptor.

The membrane-integrated polysulphide reductase (Psr) of Wolinella succinogenes is part of the electron transport chain catalyzing polysulphide reduction by formate or hydrogen. The isolated enzyme catalyzes sulphide oxidation by dimethylnaphthoquinone. The two hydrophilic subunits, PsrA and PsrB of the enzyme, are encoded by genes that form an apparent operon psrABC together with a third gene. Using homologous recombination, three deletion mutants of W. succinogenes were constructed that lack psrC, psrBC or the whole psr operon. The mutants grown with formate and fumarate were fractionated, and the cell fractions were analyzed for the presence of PsrA and enzyme activity. It was concluded that: (a) polysulphide reductase is a constituent of the wild-type chain catalyzing electron transport from formate to polysulphide; (b) the gene psrC encodes a subunit that anchors the enzyme in the membrane and is required for electron transport; (c) PsrA which probably carries the substrate site, is exposed to the bacterial periplasm; (d) PsrA and PsrB are required for the activity of sulphide oxidation with 2,3-dimethyl-1,4-naphthoquinone. Surprisingly, the delta psrABC mutant could grow with formate and polysulphide. The membrane fraction of the mutant grown under these conditions contained an enzyme that replaced polysulphide reductase in electron transport, and catalyzed sulphide oxidation with 2,3-dimethyl-1,4-naphthoquinone.

Electron Transport↗
PubMed1994

Abrasion of surface components in endosseous implants depending on their shape and coating.

To investigate titanium surface abrasion of dental implants by mere insertion into the bone, we tested 20 implants of different shape, surface, and length. Under in vitro conditions, it could be proved that longer implants had more abrasion than cylindric implants, that screw implants had more abrasion than cylindric implants, that carved threads caused less abrasion than uncarved ones, and that plasma-flame-coated implants had more abrasion than implants with polished surfaces. Possible causes of the metal abrasion are discussed.

Animals↗
PubMed1992

Cloning and nucleotide sequence of the psrA gene of Wolinella succinogenes polysulphide reductase.

The polysulphide reductase (formerly sulphur reductase) of Wolinella succinogenes is a component of the phosphorylative electron transport system with polysulphide as the terminal acceptor. Using an antiserum raised against the major subunit (PsrA, 85 kDa) of the enzyme, the corresponding gene (psrA) was cloned from a lambda-gene bank. The N-terminal amino acid sequence of PsrA mapped within the psrA gene product, which also contained an apparent signal peptide. Downstream of the psrA gene two more open reading frames (psrB and psrC) were found. The three genes may form a transcriptional unit with the transcription start site in front of psrA. The three genes were present only once on the genome. PsrA is a hydrophilic protein homologous to the largest subunits of six prokaryotic molybdoenzymes. PsrB is predicted to be hydrophilic, to contain ferredoxin-like cysteine clusters and to be homologous to the smaller hydrophilic subunits of four molybdoenzymes. PsrC is predicted to be a hydrophobic protein that could possibly serve as the membrane anchor of the enzyme.

Amino Acid Sequence↗
PubMed1992

The quinone-reactive Ni/Fe-hydrogenase of Wolinella succinogenes.

The hydrogenase (Hyd) isolated from the cytoplasmic membrane of Wolinella succinogenes consists of three polypeptides (HydA, HydB and HydC) and contains cytochrome b (6.4 mumol/g protein), which was reduced upon the addition of H2. The enzyme catalyzed the reduction of 2,3-dimethyl-1,4-naphthoquinone with H2, in contrast to an earlier preparation which was made up of HydA and HydB only and did not contain cytochrome b (Unden, G., Böcher, R., Knecht, J. & Kröger, A. (1982) FEBS Lett. 145, 230-234). This suggests that HydC is a cytochrome b which serves as a mediator in the electron transfer from H2 to the quinone. The hydrogenase genes were cloned, sequenced and identified by sequence comparison with the N-termini of the three subunits. The three genes were arranged in the order hydA, hydB, hydC, with the transcription start site in front of hydA, and were present only once on the genome. Separated by an intergene region of 69 nucleotides, hydC was followed by at least two more open reading frames of unknown function. The amino acid sequences derived from hydA, hydB and hydC were similar to those of the membrane Ni-hydrogenases of seven other bacteria. HydA and HydB also showed similarity to the small and the large subunits of periplasmic Ni-hydrogenases. HydC was predicted to contain four hydrophobic segments which might span the bacterial membrane. Two histidine residues located in hydrophobic segments are conserved in the corresponding sequences of the other membrane hydrogenases and might ligate the haem B.

Amino Acid Sequence↗
PubMed1991

[Individually controlled sedation using Midazolam].

Midazolam might be an alternative to general anesthesia for noncooperative children. 40 children were treated during 94 midazolam sedations to evaluate the potential dental therapy. An average of 2 fillings and 1 endodontic treatment was possible per sedation. The initial Midazolam dosage was 0.6 mg/kg. Every 15 min another 0.3 mg Midazolam/kg were administered to maintain the treatability of the children. 30 min after the initial Midazolam dosage dental treatment could be started. The average duration of a sedation was 76 min. Our results suggest that sedations complement under dental treatment general anesthesia.

Anesthesia, Dental↗
PubMed1991

[Treatment of deciduous teeth under rectal Midazolam sedation].

Individual controlled sedation using Midazolam proves to be a valuable addition to the range of therapeutic options for non-cooperative children. In a clinical study the oral and rectal routes of administration were compared with each other. Rectal application allowed considerably better dose adjustment. While the quality of sedation and the therapeutic range were equal with both routes, rectal application had the advantage that treatment can be commenced sooner. The sedation was of shorter duration and left the patient with less unpleasant memories. Rectal application was easier and required a smaller amount of Midazolam than oral administration.

Administration, Oral↗
PubMed1978

[Agranulocytosis and intravenous cloxacillin].

Two patients receiving parenteral cloxacillin treatment developed agranulocytosis. Upon discontinuation of the drug, the number of leukocytes rapidly returned to normal. It is likely that an immunologic mechanism may be implicated in this drug-induced blood dyscrasia.

Adult↗
PubMed1978

[Pseudothrombopenia (proceedings)].

Two cases of spurious thrombocytopenia are reported, one induced by platelet satellitism and the other by platelet aggregation. These phenomena occur in vitro, only in the presence of EDTA and are linked with the presence of IgG in the patients' sera.

Aged↗
PubMed1977

[Comparison between the presence of specific circulating immune complexes and the leukocyte migration inhibition test in different clinical forms of hepatitis B].

Circulating immune complexes were measured by a radioimmunoassay specific for HB complexes in different clinical situations related to hepatitis B virus infection. The leukocyte migration inhibition test (LMIT) was performed simultaneously. Comparison with the clinical situation suggests that immune complexes are not responsible for the lesions, but that these lesions might be produced by the immunity demonstrated by the LMIT. A deficiency of this immunity is responsible for the persistence of infection. However, in chronic active hepatitis, LMIT is as deficient as in carriers and in this form of hepatitis the frequency and quantity of complexes are the highest: it is thus possible that in this case the lesions are nevertheless produced by the complexes.

Antigen-Antibody Complex↗