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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 163 records · Page 9Linked to original sources
PubMed2000

Development of a static simulator of the mandible.

Our aim was to build and assess a static mandibular simulator capable of reproducing various masticatory exercises as closely as possible to physiological situations. Unlike existing devices that reproduce a small number of exercises and of muscular bundles, our simulator is able to reproduce all types of effort in the sagittal plane and integrates eleven muscular groups considered by the majority of authors as being the most important in mastication. The value of our simulator arises from its ability to replicate the external forces (including muscular traction, intra-articular reaction and resultant forces applied to the mandible) as determined in vivo during previous studies. The importance of such a versatile simulator, in addition to enabling study of the mechanical behaviour of the mandible, is that it greatly enhances evaluation of a possible mathematical model by means of finite element analysis. Stages of the development and evaluation of this device are described.

Computer Simulation↗
PubMed2000

[Injuries and being injured. Hidden wounds after accident injuries].

Motor vehicle accidents may cause apart from physical also psychological aftermath. Despite of posttraumatic psychologic symptoms may remit after 2-3 months, 10-20% of the injured persons will develop sustainable psychopathological symptoms. This report aims at an overview on possible psychopathological disturbances and their perpetuating conditions. Possible treatments are shown and the necessity of an interdisciplinary cooperation with the aim of a secondary prevention is emphasized.

Accidents, Traffic↗
PubMed2000

[Health behavior of smokers--results of the TACOS (Transitions in Alcohol Consumption and Smoking) Study].

The German TACOS Project (Transitions in Alcohol Consumption and Smoking) provided an opportunity to examine the patterns of health behaviours (nutrition, physical activity, alcohol consumption) of current smokers, ex-smokers and non-smokers with special regard to different degrees of severity of nicotine dependence. Data were collected in the adult general population of Lübeck and 46 surrounding communities, resulting in a representative sample of 4075 individuals. In this sample, 37.3% were current smokers, 22.5% were ex-smokers, 25.0% of smokers were severely nicotine-dependent. As in other empirical investigations, current smokers had an unhealthy lifestyle in general. Smokers compared to ex-smokers and non-smokers consumed unhealthy foods more frequently, reported less physical activity and were more likely to consume hazardous levels of alcohol. Special attention was paid to comparing different degrees of severity of nicotine dependence. A high degree of nicotine dependence was associated with poor health behaviours. Data show that smoking, unhealthy nutrition, lack of physical activity, and hazardous levels of alcohol consumption occur in combination and that unhealthy behaviour patterns vary according to the severity of nicotine dependence. The presence of multiple unhealthy behaviours requires special secondary preventive interventions for smokers. The association of these combined health hazards must be controlled in determining the independent health risk due to one of these factors.

Adolescent↗
PubMed2000

Hormonal control of renal and systemic glutamine metabolism.

Glutamine is the most abundant free amino acid in the human body. Recent studies indicate that it may be an important vehicle for interorgan nitrogen and carbon transport. However, relatively little is known about hormonal factors regulating its metabolism in humans. We review here our recent work on the effects of insulin, glucagon and epinephrine on plasma glutamine kinetics and its conversion to glucose by liver and kidney.

Epinephrine↗
PubMed2000

Deletion of the nitrate reductase N-terminal domain still allows binding of 14-3-3 proteins but affects their inhibitory properties.

Nitrate reductase (NR) is post-translationally regulated by phosphorylation and binding of 14-3-3 proteins. Deletion of 56 amino acids in the amino-terminal domain of NR was previously shown to impair this type of regulation in tobacco (Nicotiana plumbaginifolia) (L. Nussaume, M. Vincentez, C. Meyer, J.-P. Boutin, M. Caboche [1995] Plant Cell 7: 611-621), although both full-length NR and deleted NR (DeltaNR) appeared to be phosphorylated in darkness (C. Lillo, S. Kazazaic, P. Ruoff, C. Meyer [1997] Plant Physiol 114: 1377-1383). We show here that in the presence of Mg(2+) and phosphatase inhibitors, NR and endogenous 14-3-3 proteins copurify through affinity chromatography. Assay of NR activity and western blots showed that endogenous 14-3-3 proteins copurified with both NR and DeltaNR. Electron transport in the heme-binding domain of DeltaNR was inhibited by Mg(2+)/14-3-3, whereas this was not the case for NR. This may indicate a different way of binding for 14-3-3 in the DeltaNR compared with NR. The DeltaNR was more labile than NR, in vitro. Lability was ascribed to the molybdopterin binding domain, and apparently an important function of the 56 amino acids is stabilization of this domain.

14-3-3 Proteins↗
PubMed2000

Significance of saliva for the denture-wearing population.

UNLABELLED: This paper summarises a series of studies already published in German and presents new data related to the aetiology of the 'dry mouth' and its associated problems. AIMS: To study factors affecting mucous and serous salivary gland secretion, the aetiology of the 'dry mouth' and its associated problems, causative factors for hyposalivation and it's treatment. SETTING: Two university dental hospitals. SUBJECTS: 587 denture wearers and 521 control subjects, and autopsy material. INTERVENTIONS: Exercise, chewing, water, oestrogen, pilocarpine, and anetholtrithion therapy, biopsy of the minor glands. MAIN OUTCOME MEASURES: Palatal secretion (PAL, microL/cm2/min) and parotid salivary flow (PAR), subjective complaints and clinical findings. RESULTS: Resting flow rates for PAL between 0 and 65 microliters/cm2/min were seen in every age group. The flow rates of PAR (0 to 3.7 ml/10 min) were not correlated with PAL. Most patients with a resting flow rate of PAL < or = 6.0 microliters/cm2 suffer from a 'dry mouth' and Burning Mouth Syndrome (BMS) or oral dysaesthesia (OD) with or without chronic lesions of the oral mucosa. Etiological factors for the incidence of reduced PAL and associated problems include xerostomic drugs, oestrogen deficiency, radiotherapy, thyroid dysfunction, smoking or continuous wearing of complete upper dentures. PAL also correlated with the retention of upper complete dentures. PAL was correlated with the water content of epithelial tissues. PAL and PAR were both increased by drinking ample fluid, improving their circulation by physical exercises, chewing intensively, or taking oestrogens, pilocarpine, anetholtrithion. CONCLUSIONS: Variation in palatal salivary secretion occurs and is clinically important.

Adult↗
PubMed2000

Characterization of three XylT-like [2Fe-2S] ferredoxins associated with catabolism of cresols or naphthalene: evidence for their involvement in catechol dioxygenase reactivation.

The xylT gene product, a component of the xylene catabolic pathway of Pseudomonas putida mt2, has been recently characterized as a novel [2Fe-2S] ferredoxin which specifically reactivates oxygen-inactivated catechol 2,3-dioxygenase (XylE). In this study, three XylT-like proteins potentially involved in the catabolism of naphthalene (NahT) or cresols (PhhQ and DmpQ) have been overexpressed in Escherichia coli, purified, and compared with respect to their biochemical properties and interaction with XylE. The three XylT analogues show general spectroscopic characteristics common to plant-type [2Fe-2S] ferredoxins as well as distinctive features that appear to be typical for the XylT subgroup of these proteins. The midpoint redox potentials of the PhhQ and DmpQ proteins were -286 mV and -323 mV, respectively. Interestingly, all purified XylT-like proteins promoted in vitro reactivation of XylE almost as efficiently as XylT. The interaction of XylE with XylT and its analogues was studied by cross-linking experiments using the 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. A polypeptide band with an M(r) of 46,000, which corresponded to the cross-linked product between one XylE subunit and one molecule of ferredoxin, was obtained in all cases. The formation of the complex was affected by ionic strength, indicating that electrostatic forces are involved in the dioxygenase-ferredoxin interaction. In complementation experiments, plasmids expressing xylT or its analogues were introduced into an XylT-null mutant of P. putida which is unable to grow on p-methylbenzoate. All transconjugants regained the wild-type phenotype, indicating that all analogues can substitute for XylT in the in vivo reactivation of XylE. Our results provide evidence for a subgroup of [2Fe-2S] ferredoxins with distinct biochemical properties whose specific function is to reactivate intrinsically labile extradiol ring cleavage dioxygenases involved in the catabolism of various aromatic hydrocarbons.

Amino Acid Sequence↗
PubMed2000

Insulin-induced increment of coronary flow reserve is not abolished by dexamethasone in healthy young men.

Hyperinsulinemia is a risk factor for coronary artery disease. Previous studies have reported that hyperinsulinemia increases cardiac and skeletal muscle sympathetic nerve activity and skeletal muscle blood flow in normal subjects. However, little is known about insulin's effects on myocardial blood flow in humans. The purpose of this study was to investigate whether physiological hyperinsulinemia affects myocardial blood flow and flow reserve in healthy subjects. Additionally, the role of the sympathetic nervous system in regulating insulin's effects on coronary perfusion was tested. We used positron emission tomography and oxygen-15-labeled water to measure myocardial blood flow and coronary flow reserve in 16 healthy nonobese men (age, 34 +/- 4 yr; maximal aerobic capacity, 32 +/- 3 mL x g(-1) x min(-1); blood pressure, 118 +/- 10/65 +/- 8 mm Hg) at fasting and during euglycemic hyperinsulinemic clamp (1 mU x kg(-1) x min(-1) for 80 min). To study the role of the sympathetic nervous system, each subject was studied twice: once after administration of dexamethasone (dexa+) for 2 days (2 mg per day) and once without previous medication (dexa-). All studied subjects had normal left ventricular mass, function, and findings in stress echocardiography. Resting myocardial blood flow was 0.76 +/- 0.19 mL x g(-1) x min(-1), and a significant increase in flow was detected after adenosine infusion (140 microg/kg x min for 5 min i.v.), both in the basal fasting state (P < 0.001) and during hyperinsulinemia (P < 0.001). However, the flow response to adenosine was significantly higher during hyperinsulinemia, thus leading to a higher hyperemic flow (3.38 +/- 0.97 vs. 4.28 +/- 1.57 mL x g(-1) x min(-1), basal vs. hyperinsulinemic, P < 0.01) and higher coronary flow reserve (4.6 +/- 1.2 vs. 5.8 +/- 1.9, respectively, P < 0.05). Pretreatment with dexamethasone did not significantly change the resting blood flow [0.72 +/- 0.22 vs. 0.76 +/- 0.19 mL x g(-1) x min(-1), dexa+ vs. dexa-, not significant (NS)], the adenosine stimulated flow (3.56 +/- 1.49 vs. 3.38 +/- 0.97 mL x g(-1) x min(-1), respectively, NS), or the hyperinsulinemic adenosine-stimulated blood flow (4.68 +/- 1.74 vs. 4.28 +/- 1.57 mL x g(-1) x min(-1), respectively, NS). Coronary flow reserves in the basal state (5.3 +/- 2.7 vs. 4.6 +/- 1.2 mL x g(-1) x min(-1), dexa+ vs. dexa-, NS) and during hyperinsulinemia (6.8 +/- 2.9 vs. 5.8 +/- 1.9 mL x g(-1) x min(-1), respectively, NS) tended to be (but were not) significantly higher after dexamethasone treatment. These results demonstrate that insulin acts as a vasodilatory hormone also in the coronary vasculature. Because the insulin-induced increment of myocardial flow reserve remained unchanged by dexamethasone pretreatment, centrally mediated sympathetic activation seems not to play a major role in regulating insulin action on myocardial perfusion in healthy subjects.

Adenosine↗
PubMed2000

Gender differences in natural recovery from alcohol dependence.

OBJECTIVE: Data from epidemiological research reveal that most alcohol dependent individuals recover without professional treatment. Little is known, however, about individuals remitting from alcohol dependence without formal help, and almost no data are available with respect to gender differences in natural recovery. METHOD: Women (n = 38) and men (n = 106) who remitted from alcohol dependence according to DSM-IV without utilization of formal help (treatment or self-help groups) are compared. A standardized interview assessed reasons for not seeking help, and triggering mechanisms and maintenance factors of remission. RESULTS: Compared with male subjects, female subjects, prior to remission, experienced lower extents of social pressure to change drinking behavior, drove less often under the influence of alcohol, revealed less satisfaction with different life domains and reported a higher impact of health problems on the remission process. Female subjects also informed fewer individuals about their former drinking problems. CONCLUSIONS: Female and male natural remitters differ in factors that trigger the process as well as the maintenance of natural remission.

Adult↗
PubMed2000

Gingival lesions and nasal obstruction in an immunosuppressed patient post-liver transplantation.

Although rare, metastatic hepatocellular carcinoma (HCC) presenting only to the mandible, gingiva, and nasal cavity in patients subsequently found to have primary HCC has been reported. In the age of transplantation, certain HCC patients may receive treatment with an orthotopic liver transplant. Due to the proclivity of HCC for early micrometastases, immunosuppressive therapy can induce significant metastatic lesions. Nasal mass obstruction, gingival lesions, or facial growths in this population must be considered metastatic until proven otherwise.

Adult↗
PubMed2000

Laparoscopic antireflux surgery: comparative study of Nissen, Nissen-Rossetti, and Toupet fundoplication. Société Française de Chirurgie Laparoscopique.

BACKGROUND: The aim of this retrospective study was to compare the results of Nissen, Nissen-Rossetti, and Toupet laparoscopic fundoplication in terms of gastroesophageal reflux disease (GERD). METHODS: From 1992 to 1996, 1,470 laparoscopic fundoplications were performed using one of three procedures: Nissen (n = 655), Nissen-Rossetti (n = 423), and Toupet (n = 392). Preoperative checkup included esophagogastroduodenoscopy in 1,437 patients (97. 7%), esophageal manometry in 934 patients (63.5%), and 24-h pH-metry in 799 patients (54.3%). The results were estimated at 1 month, 3 months, and 2 years. Patients unable to visit the hospital center were contacted by telephone. RESULTS: The three groups were quite similar regarding demographic data such as age, gender, preoperative clinical symptoms, and duration of GERD. One death (0.07%) occurred. At 3 months, there were no differences among the three groups concerning conversion, morbidity, dysphagia, early reintervention, or postoperative length of stay. The length of surgery was more important in the Toupet procedure. In the Nissen group, there were fewer Visick grade I patients but more Visick grade III patients. At 2 years, the recurrence and reintervention rates were similar. The overall residual severe dysphagia rate was 0.35% (n = 5). In the Nissen group, there were fewer Visick grade I patients but more in Visick grade II patients. There was no difference in Visick grade III and IV among the groups. More than 90% of the patients were satisfied (Visick I + Visick II), with no significant difference among the three groups. CONCLUSIONS: The results of this study do not differ significantly from the data reported in the literature, suggesting such surgical techniques are effective and well tolerated, and that both can be properly used in the treatment of GERD.

Adolescent↗
PubMed2000

Maintenance factors of recovery from alcohol dependence in treated and untreated individuals.

BACKGROUND: Research on natural recovery from alcohol dependence has focused mainly on triggering mechanisms of the remission process. Only a few studies have considered maintenance factors of natural recovery. METHODS: In the present study, 93 natural remitters and 42 self-help group participants were compared. Both groups remitted from alcohol dependence according to DSM-IV criteria. Several alcohol-related variables and maintenance factors of the remission process were assessed in a personal interview by using standardized questionnaires. RESULTS: Logistic regression analysis that focused on maintenance factors showed that, independent from direct self-help group context, self-help group attendees informed more individuals about their former alcohol problems and sought social support more often as a coping strategy to deal with craving. No further group differences could be identified. CONCLUSIONS: Self-help group participants revealed a higher social engagement to maintain their recovery. Besides this major difference, data support the assumption that more commonalities than differences exist within successful recoveries from alcohol dependence, independent of help-seeking status.

Adaptation, Psychological↗
PubMed1999

[Cardiac scanning with positron emission tomography--PET. Clinical use and research aspect].

Assessment of regional myocardial glucose metabolism and regional myocardial perfusion has become possible with positron emission tomography (PET). These parameters are of importance in distinguishing viable from fibrotic myocardium in patients with ischaemic heart disease. PET scanning appears to be the method of choice in these patients, which has led to an increased clinical application of PET as a method usable to select patients with severe heart disease before potential revascularisation. In the present review, PET technology is briefly described, together with an overview of the scientific evidence supporting the clinical application of cardiac PET. Finally, its applications in the fields of pathophysiology and pharmacology are briefly described.

Denmark↗
PubMed1999

Oncogenic Ras inhibits Fas ligand-mediated apoptosis by downregulating the expression of Fas.

Tumor growth is the result of deregulated tissue homeostasis which is maintained through the delicate balance of cell growth and apoptosis. One of the most efficient inducers of apoptosis is the death receptor Fas. We report here that oncogenic Ras (H-Ras) downregulates Fas expression and renders cells of fibroblastic and epitheloid origin resistant to Fas ligand-induced apoptosis. In Ras-transformed cells, Fas mRNA is absent. Inhibition of DNA methylation restores Fas expression. H-Ras signals via the PI 3-kinase pathway to downregulate Fas, suggesting that the known anti-apoptotic effect of the downstream PKB/Akt kinase may be mediated, at least in part, by the repression of Fas expression. Thus, the oncogenic potential of H-ras may reside on its capacity not only to promote cellular proliferation, but also to simultaneously inhibit Fas-triggered apoptosis.

3T3 Cells↗
PubMed1999

Early embryonic death of mice deficient in gamma-adaptin.

Intracellular protein transport and sorting by vesicles in the secretory and endocytic pathways requires the formation of a protein coat on the membrane. The heterotetrameric adaptor protein complex 1 (AP-1) promotes the formation of clathrin-coated vesicles at the trans-Golgi network. AP-1 interacts with various sorting signals in the cytoplasmic tails of cargo molecules, thus indicating a function in protein sorting. We generated mutants of the gamma-adaptin subunit of AP-1 in mice to investigate its role in post-Golgi vesicle transport and sorting processes. gamma-Adaptin-deficient embryos develop until day 3.5 post coitus and die during the prenidation period, revealing that AP-1 is essential for viability. In heterozygous mice the amount of AP-1 complexes is reduced to half of controls. Free beta1- or micro1 chains were not detectable, indicating that they are unstable unless they are part of AP-1 complexes. Heterozygous mice weigh less then their wild-type littermates and show impaired T cell development.

Adaptor Protein Complex gamma Subunits↗