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T Krüger

Publications and source records attributed to T Krüger.

30 records · Page 2Linked to original sources
PubMed1997

[Stochastic relations between conscious and automatic memory processes: an expansion of the process-dissociation procedure].

This paper presents an extension of the process dissociation procedure with wordstem completion, allowing the measurement of the stochastic relation between conscious and automatic processes. The conditional probabilities of conscious remembering with and without automatic processes can be determined. The determination of these conditional probabilities succeeds due to the extension of the process dissociation procedure by an indirect wordstem completion test, without referring to the usual assumptions of the dissociation paradigm. For the evaluation of this extended process dissociation procedure a multinomial model is presented which allows the distinction between voluntary and involuntary conscious memory. The model is applied to a study by ourselves and to an experiment published by Toth, Reingold, and Jacoby (1994). The results show that the assumptions of stochastic independence or redundancy as well as exclusivity of conscious and automatic processes are often violated. Two conscious processes with different probabilities of occurrence are found; voluntary and involuntary conscious memory processes.

Awareness↗
PubMed1996

Spontaneous changes of heart rate, blood pressure, and ischemia-type ST-segment depressions in patients with hypertension without significant coronary artery disease: beneficial effects of beta-blockade.

In hypertensives, a reduced coronary flow reserve is observed and may contribute to angina pectoris and silent (painless) myocardial ischemia, which frequently occur in these patients even in the absence of coronary artery disease (CAD). To assess the frequency of ischemia-type ST-segment depressions in these patients and the influence of heart rate (HR) and blood pressure (BP) as major determinants of myocardial oxygen demand and to test the effects of beta-blocker therapy (10-20 mg betaxolol/day for 4 weeks) on these variables, simultaneous 24-h Holter and 24-h ambulatory BP monitoring was performed in 19 patients with hypertension (age, 43-71 years; nine women, 10 men) without CAD (stenosis < 50% in angiography). Before treatment, 25 periods of significant ST-segment depressions with a total duration of 470 min were observed in nine patients. ST-segment depressions were significantly correlated with preceding increases in HR and the rate-pressure product. The majority (79%) of episodes with ST-segment depression were clinically painless. In this open study, beta-blockade significantly decreased the number of episodes with ST-segment depressions to six in four of 15 patients and the total duration to 38 min (p < 0.05). The data demonstrate that HR seems to be associated with the development of ischemic ST-segment deviations in patients with hypertension without CAD. Antihypertensive therapy in these patients should target not only sufficient BP control, but also reduction of ischemic events.

Adrenergic beta-Antagonists↗
PubMed1996

Tibial lengthening. Epiphyseal and callus distraction compared in 39 patients with 3-14 years follow-up.

We examined 32 patients with 39 lengthenings (mean 8 cm) of the lower leg 3-14 years postoperatively. 23 distraction epiphyseolyses and 16 corticotomies with callus distraction had been carried out using the llizarov system. Both procedures yielded the same healing indices and the number of problems and complications was the same in the two groups. After distraction epiphyseolysis, serious complications of the knee and greater deviations from the normal leg axis were commoner than after callus distraction, which we now prefer.

Adolescent↗
PubMed1995

McrB: a prokaryotic protein specifically recognizing DNA containing modified cytosine residues.

Restriction of DNA by the Escherichia coli K-12 McrBC restriction endonuclease, which consists of the two subunits McrB and McrC, depends on the presence of modified cytosine residues in a special constellation. From previous work by others it was known that restriction of 5-methylcytosine-containing DNA requires two methylated 5'-PuC sites separated by approximately 40-80 non-defined base pairs. Here we show that binding of the McrBC nuclease is mediated exclusively by the McrB subunit. McrB has a low affinity for non-methylated DNA, with which it forms low molecular weight complexes. The affinity for DNA is significantly increased, with variations depending on the sequence context, by hemi- or fully methylated 5'-PuC sites. Binding to such substrates yields high molecular weight complexes, presumably involving several McrB molecules. Methylation at unique 5'-PuC sites can be sufficient to stimulate DNA binding by McrB. As such substrates are not cleaved by the nuclease, restriction apparently requires the coordinated interaction of molecules bound to neighbouring 5'-PumC sites. The binding properties of McrB exhibit some similarities to recently identified eukaryotic proteins interacting in a non-sequence-specific manner with DNA containing methylated 5'-CpG sequences and might point to a common molecular origin of these proteins. In addition to DNA, McrB also binds GTP, an essential cofactor in DNA restriction by McrBC. McrC neither binds to DNA nor modulates the DNA binding potential of McrB. As McrC is essential for restriction it appears to predominantly function in catalysis.

Bacterial Proteins↗
PubMed1992

Characterization of the mcrBC region of Escherichia coli K-12 wild-type and mutant strains.

We have carried out an analysis of the Escherichia coli K-12 mcrBC locus in order to (1) elucidate its genetic organization, (2) to identify the proteins encoded by this region, and (3) to characterize their involvement in the restriction of DNA containing methylated cytosine residues. In vitro expression of recombinant plasmids carrying all or portions of the mcrBC region revealed that the mcrB and mcrC genes are organized as an operon. The mcrBC operon specifies five proteins, as evident from parallel in vitro and in in vivo expression studies. Three proteins of 53, 35 and 34 kDa originate from mcrB expression, while two proteins of 37 and 16 kDa arise from mcrC expression. Products of both the mcrB and mcrC genes are required to restrict the methylated substrate DNA used in this study. We also determined the nature of mutant mcrBC loci in comparison to the E. coli K-12 wild-type mcrBC locus. A major goal of these studies was to clarify the nature of the mcrB-1 mutation, which is carried by some strains employed in previous analyses of the E. coli K-12 McrBC system. Based on our analyses the mutant strains investigated could be divided into different complementation groups. The mcrB-1 mutation is a nonsense or frameshift mutation located within mcrB. It causes premature termination of mcrB gene product synthesis and reduces the level of mcrC gene expression. This finding helps to understand an existing conflict in the literature. We also describe temperature-sensitive McrA activity in some of the strains analysed and its relationship to the previously defined differences in the tolerance levels of E. coli K-12 mcrBC mutants to cytosine methylation.

Bacterial Proteins↗
PubMed1992

[Percutaneous Silastic catheters in newborn and premature infants. A report of experiences with 497 catheters in 5 years].

BACKGROUND AND METHODS: Central catheters are an important prerequisite for adequate parenteral nutrition in preterm infants. However, a variety of complications have been shown to be associated with central lines: septicemica, thrombotic complications, mechanical complications. In this retrospective analysis we summarize our recent experience with central silastic catheters. RESULTS: Within a five-year-period (1986-1990). 497 silastic-catheters were inserted in 366 high risk neonates (mean birthweight 1360 g; 1060-1740 g, 25.-75. percentile) treated at the NICU, Department of Pediatrics, University of Göttingen. 451 catheters which were placed in a central position, were removed after an average duration of 11 days (mean; 8-18 days, 25.-75. percentile). During the observation period, 62.8 percent of the catheters were purposely removed. Making use of the Kaplan-Meier-curve, we calculated how long the catheter could stay without complications; 50% of all catheters could be expected to be in place for 25 days. The incidence of septicemia was 1.9%, bacterial contamination of the catheters was evident in 22% of all central lines. The most predominant microorganisms responsible for catheter-contamination were coagulase-negative staphylococci. In addition, catheters were removed because of signs of phlebitis or suspected thrombotic complications (11.1%), and mechanical complications (dislocation, occlusion; 11.7%). Due to malposition of the central catheter two preterm infants developed pericardial effusions. There was no correlation between the site where the catheter was inserted and these complications. CONCLUSION: Central silastic catheters wherever clinically indicated are a valuable adjunct in the parenteral nutrition on high risk neonates.

Catheterization, Central Venous↗
PubMedDate not supplied

[Etiology of early loosening after aseptic cup replacement using allogenic bone blocks and cement-free press-fit cups].

PURPOSE: There are two problems using structural allografts in revision total hip surgery. The long-term stability of bulk allografts and the intraoperative primary stability of the graft and implant limit the success of this revision philosophy. The purpose of this study was to analyse the reasons of early loosening of cementless cups after reconstruction with bulk allografts. METHOD: In a retrospective study 78 revisions were analysed radiologically. The preoperative stage of bone destruction, the size of allografts, the implant-allograft coverage, and the position of implants were analysed in X-ray series. RESULT: There were 12 (15.3%) cases with aseptic and 5 (6%) cases with septic cup loosening, after revision surgery, with an average follow-up of 37 (25-84) months. All of these failures were registered in the first 12 months postoperatively. Large bone defects and an implant-allograft coverage of more than 50% are significant (p < 0.001) risk factors of early aseptic loosening. CONCLUSIONS: It is important to give careful attentions to primary stability, especially in revision total hip arthroplasty using structural allografts and cementless cups. For primary stability as well as secondary stability a stable fixation with as large as possible areas of contact between implant and living bone is necessary. The limit of the method (allograft and cementless cup) is to be seen in stage 2B according Paprosky (1990). In larger defects alternative reconstruction methods have to be used.

Acetabulum↗
PubMedDate not supplied

[ROBODOC--a path into the future of hip endoprosthetics or an investment error?].

GOAL: The Orthopaedic Department of Martin-Luther-University has been using computer-guided, robot-assisted surgery in cementless total hip arthroplasty since June 1997. The goal of the present paper is to critically evaluate the advantages and disadvantages of the ROBODOC system when using two different femoral components and the employment of the system in orthopaedics in general. METHOD: Between June 1997 and August 1999 87 procedures have been performed using the ROBODOC system. 48 ABG stems and 39 OSTEOLOC stems manufactured by HOWMEDICA were used. The results are based on a prospective study. RESULTS: The main advantage of the system is the excellent three-dimensional preoperative planning and the precise execution of the preoperative plan during surgery. Problematic situations of the proximal femur can be evaluated and the optimal position of the femoral component can be guaranteed. Investigations on cadaver femurs showed significant differences in the bone-implant contact. The first results let us expect some advantage in congenital and acquired femoral deformities. CONCLUSION: The ROBODOC system has to be critically considered as an alternative to hand implantation. In our opinion, it should be used only under certain circumstances considering the current technical progress. Only in these cases the potential of the system can be used beneficially.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

Cardiovascular and endocrine alterations after masturbation-induced orgasm in women.

OBJECTIVE: The present study investigated the cardiovascular, genital, and endocrine changes in women after masturbation-induced orgasm because the neuroendocrine response to sexual arousal in humans is equivocal. METHODS: Healthy women (N = 10) completed an experimental session, in which a documentary film was observed for 20 minutes, followed by a pornographic film for 20 minutes, and another documentary for an additional 20 minutes. Subjects also participated in a control session, in which participants watched a documentary film for 60 minutes. After subjects had watched the pornographic film for 10 minutes in the experimental session, they were asked to masturbate until orgasm. Cardiovascular (heart rate and blood pressure) and genital (vaginal pulse amplitude) parameters were monitored continuously throughout testing. Furthermore, blood was drawn continuously for analysis of plasma concentrations of adrenaline, noradrenaline, cortisol, prolactin, luteinizing hormone (LH), beta-endorphin, follicle-stimulating hormone (FSH), testosterone, progesterone, and estradiol. RESULTS: Orgasm induced elevations in cardiovascular parameters and levels of plasma adrenaline and noradrenaline. Plasma prolactin substantially increased after orgasm, remained elevated over the remainder of the session, and was still raised 60 minutes after sexual arousal. In addition, sexual arousal also produced small increases in plasma LH and testosterone concentrations. In contrast, plasma concentrations of cortisol, FSH, beta-endorphin, progesterone, and estradiol were unaffected by orgasm. CONCLUSIONS: Sexual arousal and orgasm produce a distinct pattern of neuroendocrine alterations in women, primarily inducing a long-lasting elevation in plasma prolactin concentrations. These results concur with those observed in men, suggesting that prolactin is an endocrine marker of sexual arousal and orgasm.

Adult↗