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Biomedical subjects

S Rüdiger

Publications and source records attributed to S Rüdiger.

At least 37 records · Page 2Linked to original sources
PubMed1999

Combined systemic and local antimicrobial therapy of periodontal disease in Papillon-Lefèvre syndrome. A report of 4 cases.

4 patients, 2 pairs of siblings, suffering from Papillon-Lefèvre syndrome were treated for periodontal disease. Following extraction of hopeless teeth, the children received scaling and adjunctive systemic antibiotics (metronidazole and amoxicillin for 7 to 10 days). In addition, they performed supragingival pulsated jet irrigation with 0.06% chlorhexidine digluconate 1 x daily. In 2 siblings, A. actinomycetemcomitans was suppressed subgingivally below detectable levels, pocket probing depths were reduced to 4 mm or less, and plaque and bleeding indices were low. No further disease progression was seen over a 3-year-period. Another female patient also showed clinical improvement and suppression of subgingival A. actinomycetemcomitans and B. forsythus up to the 9-month-follow-up, while her sister showed further attachment loss over the course of 4 years. The present case reports indicated that in some patients suffering from Papillon-Lefèvre syndrome periodontal disease may be arrested by means of (i) oral hygiene instruction, (ii) extraction of severely diseased teeth, (iii) scaling, (iv) systemic antibiotics and (v) long-term antimicrobial irrigation.

Aggregatibacter actinomycetemcomitans↗
PubMed1997

Substrate specificity of the DnaK chaperone determined by screening cellulose-bound peptide libraries.

Hsp70 chaperones assist protein folding by ATP-dependent association with linear peptide segments of a large variety of folding intermediates. The molecular basis for this ability to differentiate between native and non-native conformers was investigated for the DnaK homolog of Escherichia coli. We identified binding sites and the recognition motif in substrates by screening 4360 cellulose-bound peptides scanning the sequences of 37 biologically relevant proteins. DnaK binding sites in protein sequences occurred statistically every 36 residues. In the folded proteins these sites are mostly buried and in the majority found in beta-sheet elements. The binding motif consists of a hydrophobic core of four to five residues enriched particularly in Leu, but also in Ile, Val, Phe and Tyr, and two flanking regions enriched in basic residues. Acidic residues are excluded from the core and disfavored in flanking regions. The energetic contribution of all 20 amino acids for DnaK binding was determined. On the basis of these data an algorithm was established that predicts DnaK binding sites in protein sequences with high accuracy.

Algorithms↗
PubMed1997

Working parameters of a sonic scaler influencing root substance removal in vitro.

This study assessed defect depth and volume resulting from root instrumentation using a KaVo Sonic-flex Lux 2000 L sonic scaler with a slim scaling tip (Perio-Tip no. 8) in vitro. Combinations of the following working parameters were analyzed: lateral forces of 0.5 N, 1 N, and 2 N; tip angulations of 0 degree, 45 degrees, and 90 degrees; and instrumentation time of 10 s, 20 s, 40 s, and 80 s. Defects were quantified using a three-dimensional optical laser scanner. Instrumentation time had an almost linear impact on defect depth and volume. Although lateral force (beta-weight 0.55 +/- 0.062) had a greater influence on defect volume than tip angulation (beta-weight 0.29 +/- 0.062), their effects on defect depth were similar (beta-weight 0.43 +/- 0.052 and 0.50 +/- 0.052, respectively). The combination of force and angulation showed synergistic effects resulting in a wide range of defect depths (21.9 +/- 0.96 microns to 174 +/- 28.8 microns, at 40 s) and volumes (0.056 +/- 0.019 mm3 to 0.68 +/- 0.10 mm3 at 40 s). Severe root damage (> 50 microns/40 s) did not occur at any combination of 0.5 N lateral force and/or 0 degree tip angulation. By adjusting lateral force and tip angulation, the efficacy of the assessed sonic scaler may be adapted to various clinical needs.

Dental Instruments↗
PubMed1997

Interaction of Hsp70 chaperones with substrates.

Determination of the structure of the substrate binding domain of the Escherichia coli Hsp70 chaperone, DnaK, and the biochemical characterisation of the motif it recognizes within substrates provide insights into the principles governing Hsp70 interaction with polypeptide chains. DnaK recognizes extended peptide strands composed of up to five consecutive hydrophobic residues within and positively charged residues outside the substrate binding cavity.

Binding Sites↗
PubMed1996

Regulatory region C of the E. coli heat shock transcription factor, sigma32, constitutes a DnaK binding site and is conserved among eubacteria.

The E. coli heat shock response is regulated at the transcriptional level through stress-dependent controls of the heat shock promoter-specific sigma32 subunit of RNA polymerase. A key aspect of this regulation, the sensing of stress and transmission of this information to sigma32, involves the chaperone system formed by the DnaK, DnaJ and GrpE heat shock proteins. This system mediates stress- dependent controls of levels and activity of sigma32 which rely, at least in part, on direct association of DnaK and DnaJ with sigma32. We identified DnaK binding sites within the sigma32 sequence by probing a cellulose-bound peptide library scanning sigma32. Two sites with high affinity for DnaK, containing the motifs RKLFFNLR and LRNWRIVK, were located centrally and peripherally, respectively, to the region C of sigma32, previously implicated genetically in chaperone-dependent control of sigma32 levels. Cloning and sequencing of rpoH homologs from five Gram-negative proteobacteria revealed that region C, including the DnaK binding motif central to it, is highly conserved among sigma32 homologs but missing in the other sigma factors. We propose that binding of DnaK to region C is central to a conserved regulatory mechanism allowing the sensing of stress by the heat shock gene transcription machinery.

Amino Acid Sequence↗
PubMed1996

A cycle of binding and release of the DnaK, DnaJ and GrpE chaperones regulates activity of the Escherichia coli heat shock transcription factor sigma32.

The chaperone system formed by DnaK, DnaJ and GrpE mediates stress-dependent negative modulation of the Escherichia coli heat shock response, probably through association with the heat shock promoter-specific sigma32 subunit of RNA polymerase. Interactions of the DnaK system with sigma32 were analysed. DnaJ and DnaK bind free, but not RNA polymerase-bound, sigma32 with dissociation constants of 20 nM and 5 muM respectively. Association and dissociation rates of DnaJ-sigma32 complexes are 5900- and 20-fold higher respectively than those of DnaK-sigma32 complexes in the absence of ATP. ATP destabilizes DnaK-sigma32 interactions. DnaJ, through rapid association with sigma32 and stimulation of hydrolysis of DnaK-bound ATP, mediates efficient binding of DnaK to sigma32 in the presence of ATP, resulting in DnaK-DnaJ-sigma32 complexes containing ADP. GrpE binding to these complexes stimulates nucleotide release and subsequent complex dissociation by ATP. We propose that the principles of this cycle also operate in other chaperone activities of the DnaK system. DnaK and DnaJ cooperatively inhibit sigma32 activity in heat shock gene transcription and GrpE partially reverses this inhibition. These data indicate that reversible inhibition of sigma32 activity through transient association of DnaK and DnaJ is a central regulatory element of the heat shock response.

Adenosine Diphosphate↗
PubMed1996

Adjunctive controlled topical application of tetracycline HCl in the treatment of localized persistent or recurrent periodontitis. Effects on clinical parameters and elastase-alpha1-proteinase inhibitor in gingival crevicular fluid.

35 patients receiving regular supportive periodontal therapy (SPT) and showing signs of localized persistent or recurrent periodontitis were enrolled in the study. Within 1 week after SPT, each patient had a tetracycline HCl loaded ethylene vinyl acetate co-polymer fiber placed into the periodontal pocket of 1 randomly selected tooth with persistent or recurrent periodontitis (test); the fiber was removed after 9.5+/-2.0 days. A non-adjacent tooth with persistent or recurrent periodontitis in a separate quadrant, which received no further treatment, served as a control. A total of 28 patients completed the 6-month study. Compared to control teeth, in test teeth at 6 months significantly (p<0.01) lower scores were found for gingival index, pocket probing depths, and PMN elastase-alpha1-proteinase inhibitor concentrations in gingival crevicular fluid. With the exception of plaque index scores, test teeth demonstrated significant reductions from baseline to 6 months in all parameters (p<0.05). Conversely, all parameter measurements in control teeth, except bleeding on probing, showed no significant difference between baseline and 6-month values. The results suggest that the use of controlled topical application of tetracycline HCl may improve periodontal health and reduce the risk of disease progression in localized persistent or recurrent periodontitis. Moreover, the effects of this application appear to be sustained for at least 6 months.

Administration, Topical↗
PubMed1996

Changes in membrane glycoproteins of circulating platelets after coronary stent implantation.

OBJECTIVES: To evaluate platelet function in patients with coronary stents. DESIGN: A non-randomised control trial in 30 patients who had immediate implantation of Palmaz-Schatz coronary stents because of a suboptimal angioplasty result. All patients received a standardised anticoagulation regimen including intravenous heparin (activated partial thromboplastin time (APTT) 80 to 120 s), oral vitamin K antagonist (target international normalised ratio (INR) of 3.5), and 100 mg aspirin twice daily. Platelet surface expression of glycoprotein IIb-IIIa, activated fibrinogen receptor, and P-selectin as well as binding of von Willebrand factor and fibrinogen were determined by flow cytometry in peripheral venous blood samples collected before the intervention and then daily for 4 days after it. The results were compared with those in 30 patients undergoing elective coronary balloon angioplasty. SETTING: University hospital. RESULTS: After coronary stenting surface expression of the activated fibrinogen receptor significantly increased, peaking at day 2 (P < 0.001). Similar results were found for von Willebrand factor binding and P-selectin surface expression, with a maximum at day 2 to 4 after stenting (von Willebrand factor, P < 0.001; P-selectin, P < 0.001). The changes in platelet membrane glycoproteins coincided with a significant drop in peripheral platelet count after stent placement (P < 0.01). No significant change in fibrinogen receptor activity, von Willebrand factor binding, P-selectin surface expression, or platelet count was seen in the control group. CONCLUSIONS: The present study shows that current anticoagulation treatment is inefficient in suppressing platelet activation in patients with coronary stents and, therefore, might not be the best treatment for reducing the incidence of subacute stent thrombosis.

Adult↗
PubMed1995

Identification of Actinobacillus actinomycetemcomitans in subgingival plaque by PCR.

The purpose of this study was to assess the sensitivity and specificity of the PCR in detecting Actinobacillus actinomycetemcomitans. The PCR's detection capability was compared with those of three other methods: culture-enhanced PCR (CE-PCR), colony hybridization (CH), and conventional culture with presumptive biochemical identification. A 285-bp stretch of the leukotoxin gene lktA of A. actinomycetemcomitans was amplified by PCR with primers TT-15 and TT-16. For CH, the PCR product was labeled with digoxigenin and used as a hybridization probe. Nucleotide sequence analysis of the PCR product of A. actinomycetemcomitans 1D4 and 1664 and three clinical isolates revealed complete homology among the tested strains, with only one base substitution (at position 1344) in comparison with the published sequence. With artificially infected subgingival plaque, the detection limit of PCR for A. actinomycetemcomitans was 10(3) CFU/ml of plaque suspension. Culturing subgingival plaque on tryptic soy-serum-bacitracin-vancomycin agar prior to PCR (CE-PCR) improved the limit of detection to 10(2) CFU/ml. Analysis of subgingival plaque samples from 35 patients with periodontal disease and 10 periodontally healthy subjects revealed that CE-PCR and CH had the highest overall rate of A. actinomycetemcomitans detection (both 58%), followed by PCR and culture (both 42%). With CH as the "gold standard", the sensitivities of CE-PCR, PCR, and culture were 88, 65, and 58%, respectively; the specificities were 84, 89, and 79%, respectively. The CE-PCR provided acceptable positive and negative predictive values (> or = 70%) when the prevalence of A. actinomycetemcomitans varied between 30 and 70%. PCR alone provided comparable predictive values over a narrower range of prevalence rates (30 to 50%), while culture did not afford acceptable predictive values at any prevalence rate. PCR and CE-PCR were found to be superior to culture with presumptive biochemical identification and should be the preferred methods for the detection of A. actinomycetemcomitans in subgingival plaque.

Aggregatibacter actinomycetemcomitans↗
PubMed1994

Expression of nitric oxide synthase and colocalisation with Jun, Fos and Krox transcription factors in spinal cord neurons following noxious stimulation of the rat hindpaw.

Expression of nitric oxide synthase (NOS) was investigated in neurons of lumbar spinal cord of adult rats following subcutaneous injection of formalin (FOR) in one hindpaw. NOS was visualized immunocytochemically using a specific antibody and by the NADPH-diaphorase reaction (NDP). In the untreated rat, NOS immunoreactivity (IR) and NDP were present in neurons of the superficial dorsal horn (sDH) predominantly in layers II-III, and in the deep dorsal horn (dDH) predominantly in layer X. Twenty-four hours following FOR, the numbers of neurons labelled for NOS and NDP and the density of NDP containing nerve fiber varicosities significantly increased in sDH of the ipsilateral L3-L4 segments. NOS-IR and NDP gave a rather congruent distribution of labelled neurons in the dorsal horn. In contrast, distinct NOS-IR but not NDP was visible in large diameter motoneurons and in the lateral spinal nucleus. Double labelling demonstrated that in sDH most of the NDP-reactive neurons show a close spatial relationship to fibers and varicosities immunoreactive for substance P and CGRP. These neuropeptides are considered mediators of synaptic input from nociceptive primary afferents. Colocalization of NDP with c-Jun, JunB, JunD, c-Fos, FosB and Krox-24 transcription factors was investigated in neurons of lumbar spinal cord. c-Jun, JunB, c-Fos and Krox-24 reached their maximal levels of expression 2 h after FOR and returned to basal levels after 10 h. FosB and JunD reached their maximal expression after 5 h, persisted up to 10 h and were still visible in 60%-70% of the maximal number of labelled nuclei after 24 h. This persistent expression of transcription factors might contribute to the up-regulation of NOS expression between 10 h and 24 h. In a low number of NDP neurons, suprabasal immunoreactivity of JunB, c-Fos and Krox-24 proteins was visible up to 10 h, and of JunD and FosB up to 24 h in sDH neurons; c-Jun was not expressed in NDP labelled neurons of sDH, but, similar as JunD, showed basal colocalization in preganglionic sympathetic and parasympathetic neurons. In dDH, colocalization of Jun, Fos and Krox-24 proteins in few neurons was only observed following a second FOR stimulus given 24 h after the first one. Double-staining also demonstrated that many Jun, Fos and Krox labelled neurons are in close proximity to NDP labelled nerve fibers suggesting a functional relationship between expression of immediate-early gene encoded transcription factors and presence of nitric oxide in the rat spinal cord.

Amino Acid Oxidoreductases↗
PubMed1992

Blood substitutes made on the basis of perfluorocarbons inhibit intracellular energy generation.

Although perfluorocarbons (PFC) are chemically inert, toxic reactions are observed on using them as fluorocarbon emulsions in blood substitutes. Six to twelve hours after exchanging about half of the circulating blood of conscious rats pathobiochemical reactions occur despite a high interarterial oxygen pressure. They indicate the disturbance of intracellular energy generation, which is characterized by a decrease in ATP, increase in ADP, inorganic phosphate and potassium, increase in NADH and lactate. Impurities of perfluorocarbons and effects of the surfactant were excluded to be causes of this disturbance. The following hypotheses were proposed: Storing of perfluorocarbons in the mitochondrial membrane decreases the ATP-forming proton gradient on the membrane and the electron transport in cytochromes is disturbed, respectively.

Adenosine Triphosphate↗
PubMed1982

Long-term study of virus contamination of surface water in the German Democratic Republic.

Between 1 January 1970 and 31 December 1979, a study of the concentration of viruses in surface water was carried out by 4 virological laboratories in different regions of the German Democratic Republic. All these laboratories used the same methods for virus detection.Altogether 1908 samples from 30 sampling points were evaluated. The rate of virus isolation ranged from 8% to 92% with a mean of 20%. There were considerable differences in isolation rate among the sampling points, and the rate for any particular point varied from year to year.The mean value of virus concentration, determined by the most probable number technique, was 2.7 cytopathogenic units (CU) per litre, while the maximum was 22.1 CU/litre. Viruses seen throughout the 10-year investigation included poliovirus, types 1, 2, and 3, echovirus types 6, 11, and 30, and coxsackievirus B 3 and B 5; echovirus 7 and 24, coxsackievirus B 1, and adenovirus 5 were seen occasionally. The results of the study reflected the high level of use of surface waters in the German Democratic Republic.Where water is intended for human use, e.g., as drinking-water or for recreation, reasonable safety measures, such as water treatment and disinfection, should be taken, in order to ensure that the level of viral contamination is within the permissible limits.

Germany, West↗
PubMed1981

[A two-stage technique for concentration of viruses from solutions with low virus titers (e.g., drinking water)].

The evidence of viruses in drinking water is an important component of studies of viruscirculation between man and his environment. In the two-stage concentration technique presented in this paper the method of aluminium sulphat flocculation, verified in more than 1300 investigations, is the first stage. In the second stage, aluminium hydroxide gel is at first dissolved with 1 ml of citric acid sodium citrate buffer at pH 4,7. The physico-chemical aspects of the lysis are discussed. It is from the lysate, that is not toxic for viruses, that viruses are separated by ultracentrifugation and inoculated on cell cultures. Owing to considerable constriction effect of about 20 000:1 is the method especially suitable for evidence of viruses in solutions with low virus titers (e.g. drinking water) as confirmed by a series of tests.

Aluminum Hydroxide↗