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G Schmidt

Publications and source records attributed to G Schmidt.

At least 109 records · Page 6Linked to original sources
PubMed1998

The Rho-deamidating cytotoxic necrotizing factor 1 from Escherichia coli possesses transglutaminase activity. Cysteine 866 and histidine 881 are essential for enzyme activity.

Recently, it has been reported that cytotoxic necrotizing factor 1 (CNF1) from Escherichia coli induces formation of stress fibers by deamidation of glutamine 63 of RhoA (Schmidt, G., Sehr, P., Wilm, M., Selzer, J., Mann, M., and Aktories, K. (1997) Nature 387, 725-729); Flatau, G., Lemichez, E., Gauthier, M., Chardin, P., Paris, S., Fiorentini, C., and Boquet, P. (1997) Nature 387, 729-733). By using mass spectrometric analysis, we show now that the toxin transfers ethylenediamine, putrescine, and dansylcadaverine specifically onto glutamine 63 of RhoA. RhoA was also a substrate for guinea pig liver transglutaminase, which modified not only glutamine 63, but also glutamine residues at positions 52 and 136. Treatment of the fully active N-terminal fragment of CNF1 (amino acid residues 709-1014) with iodoacetamide inhibited both deamidation and transglutamination activities. Moreover, exchange of cysteine 866 with serine blocked the enzyme activity of the N-terminal CNF1 fragment. In addition, we identified histidine 881 to be essential for the enzyme activity of CNF1. The data indicate that CNF1 shares a catalytic dyad of cysteine and histidine residues with eukaryotic transglutaminases and cysteine proteases.

Amides↗
PubMed1998

Pseudomonas aeruginosa exoenzyme S ADP-ribosylates Ras at multiple sites.

Pseudomonas aeruginosa exoenzyme S (ExoS) ADP-ribosylated Ras to a stoichiometry of approximately 2 molecules of ADP-ribose incorporated per molecule of Ras, which suggested that ExoS could ADP-ribosylate Ras at more than one arginine residue. SDS-polyacrylamide gel electrophoresis analysis showed that ADP-ribosylated Ras possessed a slower mobility than non-ADP-ribosylated Ras. Analysis of the ADP-ribosylation of in vitro transcribed/translated Ras by ExoS identified two electrophoretically shifted forms of Ras, which was consistent with the ADP-ribosylation of Ras at two distinct arginine residues. Analysis of ADP-ribosylated in vitro transcribed/translated Ras mutants possessing individual Arg-to-Ala substitutions showed that Arg-41 was the preferred site of ADP-ribosylation and that the second ADP-ribosylation event occurred at a slower rate than the ADP-ribosylation at Arg-41, but did not occur at a specific arginine residue. Analysis of bacterially expressed wild-type RasDeltaCAAX and RasDeltaCAAXR41K supported the conclusion that Arg-41 was the preferred site of ADP-ribosylation. Arg-41 is located adjacent to the switch 1 region of Ras, which is involved in effector interactions. Introduction of ExoS into eukaryotic cells inhibited Ras-mediated eukaryotic signal transduction since infection of PC-12 cells with an ExoS-producing strain of P. aeruginosa inhibited nerve growth factor-stimulated neurite formation. This is the first demonstration that ExoS disrupts a Ras-mediated signal transduction pathway.

ADP Ribose Transferases↗
PubMed1998

Bacterial cytotoxins target Rho GTPases.

Low molecular mass GTPases of the Rho family, which are involved in the regulation of the actin cytoskeleton and in various signal transduction processes, are the eukaryotic targets of bacterial protein toxins. The toxins covalently modify Rho proteins by ADP ribosylation, glucosylation, and deamidation, thereby inactivating and activating the GTPases.

Animals↗
PubMed1998

Effects of acute administration of ethanol and the mu-opiate agonist etonitazene on thyroid hormone metabolism in rat brain.

The effects of acute, low-dose administration of ethanol (1 g/kg bodyweight) and the mu-opioid receptor agonist etonitazene (30 microg/kg bodyweight) on the activities of the iodothyronine deiodinase isoenzymes were investigated in nine regions of the rat brain. The experiments were performed at three different times of the 24-h cycle (1300, 2100 and 0500 hours) and the rats were decapitated 30 and 120 min after administration of the respective drugs. Interest was focused on changes in the two enzymes that catalyze 1) 5'-deiodination of thyroxine (T4) to the biologically active triiodothyronine (T3), i.e. type II 5'-deiodinase (5'D-II) and 2) 5 (or inner-ring) deiodination of T3 to the biologically inactive 3'3-T2, i.e. type III deiodinase (5D-III). 120 min after administration of ethanol and etonitazene 5D-III activity was selectively inhibited in the frontal cortex (at 1300 and 1700 hours) and the amygdala (at all three measuring times). The 5'D-II activity was significantly enhanced 30 min after administration of etonitazene in the frontal cortex, amygdala and limbic forebrain, and after administration of ethanol in the amygdala alone. These effects on 5'D-II activity were seen at 2100 hours only. In conclusion, the two different addictive drugs both reduced the inactivation of the physiologically active thyroid hormone T3 and enhanced its production. These effects occurred almost exclusively in the brain regions which were most likely to be involved in the rewarding properties of addictive drugs. As thyroid hormones have stimulating and mood-elevating properties, an involvement of these hormones in the reinforcing effects of addictive drugs seems conceivable.

Animals↗
PubMed1998

[Standards for treatment and expert opinion on transsexuals. The German Society for Sexual Research, The Academy of Sexual medicine and the Society for Sexual Science].

Over the last two-and-a-half years a committee of experts, consisting of members of the three leading German sexology associations, developed guidelines for treating and assessing transsexuals. Their purpose is to improve the care for patients with sex identity disorders and to ensure that such care is of uniform quality to avoid erroneous decisions to the disadvantage of those affected. The guidelines are set out in full.

Diagnosis, Differential↗
PubMed1998

Oxygen-dependent regulation of the expression of the catalase gene katA of Lactobacillus sakei LTH677.

The catalase gene katA of Lactobacillus sakei LTH677 was cloned and expressed in Escherichia coli UM2, Lactobacillus casei LK1, and Lactobacillus curvatus LTH1432. The last host is a catalase-deficient plasmid-cured derivative of a starter organism used in meat fermentation. The regulation of katA expression was found to be the same in L. sakei LTH677 and the recombinant strains. The addition of H2O2 to anaerobic cultures, as well as a switch to aerobic conditions, resulted in a strong increase in KatA activity. The expression was investigated in more detail with L. sakei LTH677 and L. curvatus LTH4002. The recombinant strain LTH4002 did not accumulate H2O2 under glucose-limited aerobic conditions and remained viable in the stationary phase. Under inductive conditions, the katA-specific mRNA and the apoenzyme were synthesized de novo. Deletion derivatives of the katA promoter were produced, and the regulatory response was investigated by fusion to the beta-glucuronidase reporter gene gusA and expression in L. sakei LTH677. The fact that gene expression was subject to induction was confirmed at the level of transcription and protein synthesis. A small putative regulatory sequence of at least 25 bp was identified located upstream of the -35 site. Competition experiments performed with L. sakei LTH677 harboring the fusion constructs consisting of the katA promoter and gusA revealed that an activator protein is involved in the transcriptional induction of katA.

Aerobiosis↗
PubMed1998

Activation of Rho GTPases by Escherichia coli cytotoxic necrotizing factor 1 increases intestinal permeability in Caco-2 cells.

The cytotoxic necrotizing factor 1 (CNF1) activates Rho GTPases by deamidation of glutamine-63 and thereby induces redistribution of the actin cytoskeleton and formation of stress fibers. Here, we have studied the effects of CNF1 on the transepithelial resistance of Caco-2 cells, a human intestinal epithelial cell line, in comparison with the Rho-inactivating toxin B of Clostridium difficile. Whereas toxin B decreased the transepithelial resistance of Caco-2 cells by about 80% after 4 h, CNF1 reduced it by about 40%. Significant changes of the transepithelial resistance induced by CNF1 were detected after 3 h of incubation. Half-maximal effects were observed with 10 and 41 ng of CNF1 and toxin B per ml, respectively. Flux measurement revealed no CNF1-induced increase of fluorescein isothiocyanate-dextran permeation within the first 4 h of incubation and a 2.9-fold increase after 24 h of incubation. In contrast, toxin B induced a 28-fold increase of permeation after 24 h. As detected by rhodamine-phalloidin staining, CNF1 increased polymerization of F actin at focal contacts of adjacent cells and induced formation of stress fibers. The data indicate that not only depolymerization but also polymerization of actin and subsequent reorganization of the actin cytoskeleton alter the barrier function of intestinal tight junctions.

Bacterial Toxins↗
PubMed1998

Effect of medial displacement calcaneal osteotomy on ankle kinematics in a cadaver model.

Although medial displacement calcaneal osteotomy has been advocated for treatment of acquired pes planus, no studies have determined the biomechanical consequences at the ankle of such a procedure. The present investigation examined the alteration in ankle motion that resulted from a medial sliding calcaneal osteotomy. In dorsiflexion, the ankle specimens were found to have altered internal rotation and varus alignment. At maximal dorsiflexion, there was a 76% increase in internal rotation (4.4 degrees +/- 2.5 degrees versus 2.5 degrees +/- 1.7 degrees for intact ankles, P < 0.0004) and an increase of 425% in varus (0.42 degrees +/- 0.56 degrees versus 0.08 degrees +/- 0.34 degrees for intact ankles, P < 0.003). There were no significant differences seen in plantar flexion. Based on these results, caution is advised in the indiscriminate use of medial sliding osteotomies, because this procedure may predispose the patient to premature ankle arthritis as a consequence of the altered ankle motions.

Aged↗
PubMed1998

The effects of drinking on health of older adults.

As part of a larger health-promotion project focused on safer use of alcohol and medications by older people, 826 persons living in a small community in Eastern Ontario participated in a survey conducted by nurses in the participant's home. The survey interview varied in length from 30 to 210 minutes and covered alcohol use, medication use, health status, and other aspects of life. This report examines the relationship between drinking practices and self-reported health (overall rating of health, hospital admissions, etc.) as identified by the survey. Among survey participants who abstained from alcohol during the 12 months prior to the survey, former drinkers reported significantly poorer health than did lifetime abstainers and previous drinkers who happened to abstain in the previous year but considered themselves to be infrequent drinkers rather than former drinkers. Among current drinkers, poorer health was associated with drinking more on each occasion of drinking and with a greater total overall volume of alcoholic beverages consumed (as estimated from the drinker's usual weekly consumption), but not with more frequent drinking. Even when controlling for sex, age, education, and depressant medication use, quantity of alcoholic beverage consumption per occasion and overall volume consumed were found to contribute significantly to predicting perceived health. The implications of the findings are discussed in terms of the best ways to assess the risk level of alcohol use among older people, and with recommendations for safer alcohol use.

Aged↗
PubMed1998

Working in addictions treatment services: some views of a sample of service providers in Ontario.

Respondents in a survey of specialized addiction treatment providers indicated a strong commitment to the addictions field. In a multivariate analysis, intention to stay in the addictions field was positively related to a measure of attitudes toward staying or leaving, to age, involvement in an addictions studies program, working in a residential service, and job satisfaction. Intention to stay was negatively related to education and working in a nonresidential setting. Attention to factors that create positive attitudes to the addictions field, especially among younger, more educated people and those working in nonresidential services, is necessary to ensure a healthy future for addictions treatment.

Adult↗
PubMed1998

A distributed medical record on a Holter-ECG archiving and analysis system.

At the Department of Cardiology of the Technical University of Munich and the Deutsches Herzzentrum München cardiac disease patients are treated in close co-operation. In order to support the collaborative treatment as well as cardiological studies a distributed medical record (DMR) has been implemented on the basis of a Holter-ECG archiving and analysis system. Architecture, experiences and major benefits of the solution are reported in the paper. Between January 1995 and December 1997 6500 Holter-ECGs have been archived and analysed. The DMR is in routine operation since January 1996 for all heart catheter patients.

Attitude to Computers↗
PubMed1998

Induction of a variety of preneoplasias and tumours in the mammary glands of transgenic rats.

Although transgenic mouse models for breast cancer have frequently been reported in the literature, transgenic rat models have not been described. We have generated transgenic rats overexpressing the human transforming growth factor alpha (TGF alpha) and c-erbB-2 genes in the mammary gland under the control of the mouse mammary tumour virus (MMTV) long terminal repeat promoter, and have analysed multiple lines of these rats to the second (F2) generation. Female MMTV/TGF alpha rats frequently develop severe hyperplasias during pregnancy, and a variety of tumours of long latency. The mammary glands of MMTV/TGF alpha rats fail to involute fully after the completion of lactation. Expression of the TGF alpha transgene is highest in the hyperplasias. MMTV/c-erbB-2 female rats develop a spectrum of benign and malignant lesions, including ductal carcinoma in situ and carcinomas. Expression of the c-erbB-2 transgene is found in benign tumours such as fibroadenomas, but is highest in the carcinomas. These animals model a spectrum of lesions found in human breasts and suggest that TGF alpha overexpression can act at a relatively early stage in the pathogenesis of breast cancer in the rat, resulting in a predominantly hyperplastic response, whereas overexpression of c-erbB-2 plays a role in the induction of various benign lesions and more advanced breast carcinomas.

Animals↗
PubMed1998

[Possibilities of preliminary treatment of infected soft tissue defects by vacuum sealing and PVA foam].

The vacuum sealing technique is a simple and cost-effective method in the treatment of traumatic and chronic soft-tissue defects. Wound cavities are filled with polyvinyl alcohol foam with embedded drainage tubes. The tubes are either drawn transcutaneously through the tissue, or placed epicutaneously, depending on the condition of the wound. The wound including the adjacent skin and the drainage tubes are covered by a transparent vapor transmitting polyurethane film. When the drainage tubes are connected with a vacuum bottle, negative pressure of 60 to 80 kPa is established. The advantages of this vacuum sealing procedure are: protection against wound contamination, complete evacuation of wound fluids independent of gravity and rapid stimulation of dense, well vascularized granulation tissue. Relief of pain and early mobilisation improve the patients comfort. Between November 1994 and July 1996, 25 patients with 28 soft tissue defects underwent this procedure. Wound closure was performed in two cases with a free flap, in five cases by a loco-regional flap, in sixteen cases with mesh-grafts, in three cases by secondary closure of the wound. Two cases were definitively treated with the vacuum sealing technique.

Adolescent↗
PubMed1997

Distribution of nitric oxide synthase implies a regulation of circulation, smooth muscle tone, and secretory function in the human prostate by nitric oxide.

BACKGROUND: Nitric oxide (NO) is suggested as a mediator involved in the regulation of smooth muscle tone, blood flow, and secretory function of the genitourinary tract and originates from different NO synthase (NOS) isoforms located in endothelial, neuronal, and epithelial structures. The aim of the present study was to determine the location of endothelial and neuronal NOS in the human prostate. METHODS: Histochemical NADPH-diaphorase (NADPH-d) staining, ultrastructural NADPH examination, and NOS immunohistochemistry were performed on histologically verified nonmalignant prostate tissue from normal nonobstructive and hyperplastic obstructive human prostates. RESULTS: In the prostatic tissue, NADPH-d staining and immunohistochemistry with bNOS antibody revealed the existence of a dense nitrinergic innervation of glandular epithelium, fibromuscular stroma, and blood vessels. NADPH-d reaction in glandular epithelium was not confirmed by ecNOS or bNOS immunohistochemistry. In benign prostatic hyperplasia (BPH), the nitrinergic innervation is reduced. The vascular distribution of ecNOS provides evidence for a segmental differentiation of the NO-mediated vascular regulation. CONCLUSIONS: NO plays an important role in the autonomic innervation of all compartments of prostatic tissue. In obstructive BPH, the nitrinergic innervation is reduced compared to that in normal prostate tissue. Further studies are necessary to elucidate the complex role of NO in the prostate.

Aged↗
PubMed1997

Gln 63 of Rho is deamidated by Escherichia coli cytotoxic necrotizing factor-1.

The actin cytoskeleton is regulated by GTP-hydrolysing proteins, the Rho GTPases, which act as molecular switches in diverse signal-transduction processes. Various bacterial toxins can inactivate Rho GTPases by ADP-ribosylation or glucosylation. Previous research has identified Rho proteins as putative targets for Escherichia coli cytotoxic necrotizing factors 1 and 2 (CNF1 and 2). These toxins induce actin assembly and multinucleation in culture cells. Here we show that treatment of RhoA with CNF1 inhibits the intrinsic GTPase activity of RhoA and completely blocks GTPase activity stimulated by the Rho-GTPase-activating protein (rhoGAP). Analysis by mass spectrometry and amino-acid sequencing of proteolytic peptides derived from CNF1-treated RhoA indicate that CNF1 induces deamidation of a glutamine residue at position 63 (Gln 63) to give constitutively active Rho protein.

3T3 Cells↗
PubMed1997

Mapping of G2/M-phase prevalences of chaperon-encoding transcripts by means of a sensitive differential hybridization approach.

The sensitivity of the differential hybridization approach is significantly increased by the application of size-selected probes. RNA from elutriated phase-synchronous Ehrlich ascites tumor (EAT) cells has previously been used to prepare cell cycle phase-specific cDNA libraries in the in-vitro transcription vector pBluescript. PCR amplification of the libraries with vector-fitting primer pairs generates amplified cDNA reflecting the mRNA complexities of cells in G1, S and G2/M phases. Probes with reduced complexities were recovered after side-by-side electrophoresis of equal amounts of PCR-amplified cDNA and elution of probes from parallel gel sections. Such size-selected probes release significant differential clones which escape their detection in the conventional differential hybridization approach. Three clones hybridizing preferentially with the G2/M phase-specific probe were further characterized. The genes were identified by their nucleotide sequences. They encode proteins known to be involved in protein folding: heatshock cognate protein, HSC 70; heatshock cognate protein, HSC 73; eta subunit of the chaperonin containing TCP-1 complex, CCT. The G2/M phase-prevalent expression of these genes were further verified on the mRNA and on the protein level by Northern and Western blot analysis which confirms the significance of the differential hybridization approach and which indicates that the expression of this group of proteins increases with cell cycle progression. The expression of the chaperonin-containing TCP-1 complex appears to be specifically linked with the S to G2/M phase transition of the cell cycle.

Animals↗
PubMed1997

[Torsade de pointes tachycardia during administration of quinidine and verapamil in atrial fibrillation].

The following case report shows that life threatening arrhythmias with fatal consequences may occur after treatment with Cordichin a combination of 80 mg verapamil and 160 mg quinidine. A 65-year-old woman was treated with Cordichin due to atrial fibrillation lasting for 3 months. After the first day of treatment the patient suddenly collapsed with loss of consciousness. The patient was resuscitated 15 min later. The emergency physician diagnosed a cardiac arrest. After cardiopulmonary resuscitation and intubation stable circulation was restored. When the patient was admitted in our hospital the ECG showed numerous ventricular extrasystoles, marked prolongation of the QT interval (700 ms) (Figures 1a and b) and nonsustained polymorphic ventricular tachycardias (Figure 2). The arrhythmias could be suppressed by right ventricular stimulation after inserting a pacemaker lead. After a period of 12 h a normal QT interval was restored (Figure 3). Unfortunately the patient died 3 days later due to irreversible cerebral damage. The concept of suppressing proarrhythmic effects of quinidine by calcium antagonists is discussed. Despite theoretical advantages of a combination therapy this case report shows that life threatening dysrhythmias cannot be prevented by additional calcium antagonism.

Aged↗