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Biomedical subjects

M Geyer

Publications and source records attributed to M Geyer.

At least 73 records · Page 4Linked to original sources
PubMed1995

Prevalence of eating disorders and minor psychiatric morbidity in central Europe before the political changes in 1989: a cross-cultural study.

The prevalence of culture-bound syndromes such as eating disorders in the countries of Central and Eastern Europe is unclear and comparative epidemiological studies are lacking. Before the political changes in 1989 we therefore investigated eating disorders, eating attitudes and psychological health in two Eastern European countries and in one Western democracy. A total of 1225 female and male medical students in Hungary, the German Democratic Republic (GDR) and Austria were surveyed. The instruments included the Eating Disorder Inventory and the GHQ. The prevalence of eating disorders was calculated on the basis of simulated DSM-III-R diagnosis. In females, bulimia nervosa prevalence rates of 0.6% (95% CI 0.02, 3.46), 1% (0.2, 2.95) and 0% (0, 2.07) were calculated for Austria, Hungary and the GDR, respectively. For subclinical bulimia nervosa, the rate for Hungary (3.8%; 1.95, 6.72) was twice as high as for Austria (1.9%; 0.39, 5.5) and the GDR (1.7%; 0.36, 4.88). Hungarian subjects indicated more psychiatric 'caseness' than their GDR or Austrian counterparts. We conclude that eating disorders represented at least as common a problem in Eastern as Western Europe before the changes in political organization. This may be due to an identification process with Western values. A further increase of eating disorders in these countries induced by the recent changes may be possible.

Adult↗
PubMed1995

Substrate-assisted catalysis as a mechanism for GTP hydrolysis of p21ras and other GTP-binding proteins.

Despite many advances in understanding the structure and function of GTP-binding proteins the mechanism by which these molecules switch from the GTP-bound on-state to the GDP-bound off-state is still poorly understood. Theoretical studies suggest that the activation of the nucleophilic water which hydrolyzes GTP needs a general base. Such a base could not be located in any of the many GTP-binding proteins. Here we present a unique type of linear free energy relationships that not only supports a mechanism for p21ras in which the substrate GTP itself acts as the catalytic base driving the GTPase reaction but can also help to explain why certain mutants of p21ras are oncogenic and others are not.

Amino Acid Sequence↗
PubMed1993

Three-dimensional structures and properties of a transforming and a nontransforming glycine-12 mutant of p21H-ras.

The three-dimensional structures and biochemical properties of two mutants of the G-domain (residues 1-166) of p21H-ras, p21 (G12D) and p21 (G12P), have been determined in the triphosphate-bound form using guanosine 5'-(beta,gamma-imido)triphosphate (GppNHp). They correspond to the most frequent oncogenic and the only nononcogenic mutation of Gly-12, respectively. The G12D mutation is the only mutant analyzed so far that crystallizes in a space group different from wild type, and the atomic model of the protein shows the most drastic changes of structure around the active site as compared to wild-type p21. This is due to the interactions of the aspartic acid side chain with Tyr-32, Gln-61, and the gamma-phosphate, which result in reduced mobility of these structural elements. The interaction between the carboxylate group of Asp-12 and the gamma-phosphate is mediated by a shared proton, which we show by 31P NMR measurements to exist in solution as well. The structure of p21 (G12P) is remarkably similar to that of wild-type p21 in the active site, including the position of the nucleophilic water. The pyrrolidine ring of Pro-12 points outward and seems to be responsible for the weaker affinity toward GAP (GTPase-activating protein) and the failure of GAP to stimulate GTP hydrolysis.

Amino Acid Sequence↗
PubMed1993

[Overuse syndrome in ballet: study of the effect of a tape bandage of the upper ankle joint with motion analysis].

In six ballet dancers with overuse syndromes of the foot a study on the effect of taping on stabilisation, proprioception and muscular activity was performed. By using synchronous surface electromyography and 3-dimensional motion analysis three standard ballet positions without and with applied tape were performed. Muscular activities of pronator muscles (peroneus longus) and supinator muscles (tibialis posterior) were recorded. EMG measurements showed significant differences between patients with stable or unstable ankles and painful or pain-free feet. Applying tape led to significant changes of muscle activities in height and antagonist reflex patterns. These changes were highest in dancers with unstable ankle joints and metatarsalgia.

Adult↗
PubMed1993

[Stress reactions and stress fractures in the high performance athlete. Causes, diagnosis and therapy].

From 1987 until July 1991 70 athletes with stress reactions or stress fractures were treated in the orthopaedic department of the Hannover Medical School. The average age of the 42 male and 28 female athletes was 22.6 years. The number of athletes involved in track and field sports was 29 (41.4%), in gymnastics 9 (12.9%) and in soccer 5 (7.1%). The most common bone injured was the tibia in 29 (41.4%), followed by the tarsal navicular in 21 (30.0%), the midfoot in 17 (24.3%) and the fibula in 4 (5.7%) athletes. In three cases double stress fractures were found in adjacent locations; in one case a stress fracture of the opposite navicular occurred after the initial tarsal navicular stress fracture had healed, and in another case the tarsal navicular was found to be fractured again. Thirty-seven percent of the athletes claimed sudden increase in training intensity was the cause; 33% felt that the increased sprinting and jump activities were the reason for their complaints. In some athletes pain started after an ankle sprain. Standard diagnostic procedure consisted in X-rays in two planes and three-phase bone scanning. In tarsal navicular or tibial locations additional tomograms were performed. MRI and CT scans were reserved for unclear findings and to exclude the possibility of a tumorous or inflammatory process. A new grading system was introduced that covers all forms of stress reactions from periostitis to pseudarthrosis. Clinical symptoms, sport disabilities, radiological and bone scan findings were graded from A to D. Using a modified Wilson classification, all radiologically recognizable stress reactions could be classified.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

C-terminal structure and mobility of rabbit skeletal muscle light meromyosin as studied by one- and two-dimensional 1H NMR spectroscopy and X-ray small-angle scattering.

Intact rabbit myosin and two different C-terminal fragments of rabbit muscle light meromyosin (LMM) expressed in Escherichia coli, LMM-30, and LMM-30C', were studied by 1H NMR spectroscopy. X-ray small-angle scattering shows that at high ionic strength two polypeptide chains of LMM-30 (which consists of the C-terminal 262 amino acids of myosin heavy chain) or LMM-30C' (which corresponds to LMM-30 but lacks the last 17 residues) assemble to form an alpha-helical coiled-coil as it is found also in myosin. The last 12 C-terminal residues of one polypeptide chain of LMM-30 and the last 9 C-terminal residues of the other chain are very mobile. The last 8 residues of the two strands are equivalent from the NMR point of view and unfolded; the valine residues in position 255 in the two strands are not equivalent, suggesting an interaction between the two strands, Ser-252, Arg-253, and Asp-254 are completely immobilized in one of the polypeptide strands and partly mobile in the other. Essentially the same pattern is observed in intact myosin. In spite of the large molecular weights of LMM-30 and LMM-30C', it is possible to resolve almost all aromatic residues and to determine the pK values of all the 4 tyrosine and of 9 (out of 10) histidine residues. The tyrosine residues in the two strands are equivalent in the two polypeptide chains and both have a pK of 10.5. The pK values of the histidine residues vary between 5.7 and 7.0.

Amino Acid Sequence↗
PubMed1991

[Complex movement analysis: dynamic study of the effect of a tape bandage on pronation in high-jumping with three-dimensional movement analysis and electromyography].

Overuse syndromes in the lower extremity are a frequent problem in athletics, especially in jumping events. Athletes notice a comfortable support by using ankle taping without restriction of their performance. Up to now no objective data is available about efficiency of taping against overpronation which is frequent in high jumping. In high jumping without boots little difference of pronation between taped and untaped take off leg was found. In contrast in jumping with spikes boots a marked pronation during take off was found, which was reduced by ankle taping with a reduction of maximum medial malleolar medialisation by 77%, reduction of pronation time by 33% and time of maximum pronation by 8.2% in the take off leg. Surface electromyography showed an increased activity of M. peroneus longus by 30.7% as a plantarflector and pronator muscle with ankle taping. Activity of other jump supporting muscles of the lower extremity was little influenced.

Adolescent↗
PubMed1991

[A new mechanism of injury of the anterior cruciate ligament].

In alpine skiing various mechanisms of injury to the anterior cruciate ligament have been described. External rotation-flexion-valgus stress and hyper-extension are considered the classic mechanisms. Rupture of the anterior cruciate ligament without falling has rarely been reported. In ski racers competing in the World Cup downhill races an accumulation of isolated anterior cruciate ruptures following landing after a jump in a more or less backward position without falling has become evident in recent years. We recorded this mechanism for the first time in 1986. A ski racer landing in a bent position on flat ground after a jump documented on video tape felt a sharp pain and immediate instability, though he did not fall. Clinically hemarthrosis and a positive Lachman sign were found, and intraoperatively an isolated rupture of the anterior cruciate ligament was confirmed. Analysis of the video tape and biomechanical considerations showed that even a minimal shift of the center of body mass dorsal to the axis of the lower leg leads to an acceleration of the thigh and body oriented centrifugally, vertically and in a plantar direction against the rotational axis of the knee and to a forward rotational acceleration of the tibia by the dorsal shaft of the ski boot. This acceleration produces a massive compensatory quadriceps contraction to prevent a backward fall, followed by an "anteroposterior shift" of the femur on the tibia in the sense of an anterior drawer, which in association with other factors leads to an ACL rupture. This "anteroposterior shift mechanism" is only possible in excellent skiers with the muscular control and coordination to prevent a backward fall.

Anterior Cruciate Ligament↗
PubMed1990

Reninlike enzymes in human vasculature.

The present study was designed to identify angiotensin I (Ang I)-forming angiotensinogenases in human extrarenal vasculature and to examine the theory of Jiménez Días on their stimulation in essential hypertension. Vascular sections obtained intraoperatively from 14 normotensive and 16 hypertensive patients undergoing corrective surgery, 68 umbilical cord blood vessels from parturient women, tissue samples from nine explanted hearts, and serum from anephric and healthy individuals were investigated. Ang I-forming angiotensinogenase activities were determined enzyme-kinetically by using Ang I radioimmunoassay and purified sheep or human angiotensinogens. Three nonrenin Ang I-forming angiotensinogenases (pH optima of 4.0, 5.1, and 6.1) were identified in extrarenal vasculature, in cardiac tissues, and in plasma. Highest specific activities of nonrenin Ang I-forming angiotensinogenase (in nanograms Ang I per gram times hour; mean +/- SD) were found in cardiac tissue (2,821 +/- 497, n = 9), followed by carotid artery intima (1,448 +/- 982, n = 10), arteries (1,307 +/- 736, n = 18), and umbilical cord arteries (135 +/- 55, n = 35). Extrarenal arterial Ang I-forming angiotensinogenases were linearly correlated with those of local angiotensin converting enzyme and plasma renin activity. In essential hypertension, extrarenal arterial Ang I-forming angiotensinogenases were scattered, but not generally stimulated. The data obtained indicate the existence of nonrenin Ang I-forming angiotensinogenases in human extrarenal vasculature, in kidney, and in plasma. The postulate of stimulation of extrarenal arterial Ang I-forming angiotensinogenases in essential hypertension cannot be supported. Similar to the classification of plasma renin activity, a classification of Ang I-forming angiotensinogenase activity is proposed, consisting of patients with essential hypertension divided into subgroups exhibiting high, normal, or low vascular Ang I-forming angiotensinogenase activities.

Angiotensin I↗
PubMed1989

[Skiing injuries: analysis in a German ski area].

An analysis of frequencies, causes and injury patterns in skiing with emphasis to knee injuries was done. In our clinic next to the slopes of the ski resort Pfronten and the skiing region Ostallgäu skiing injuries contribute with 58% of all stationary treated sports injuries to a big part of our in-patients. Out of all skiing injuries 52% are ligament lesions and 63% concern the knee joint. Thus the knee ligament lesions are leading in our sports related orthopaedic surgery. The results of this analysis were compared with data from Swiss skiing areas and Austrian and German university clinics. Possible ways of injury prophylaxis are presented.

Adult↗
PubMed1989

[Injuries caused by parasailing].

The new sport of parasailing seems to be set to go through the same stages of enthusiasm, disillusionment and consolidation as hang gliding did some years ago. The high number of injuries we see in our clinic, which is in one of the areas of Germany where parasailing is most popular, shows that the phase of enthusiasm is still in full swing. A total of 48 injuries sustained during parasailing and treated in our clinic within 6 months were analyzed with reference to causes, patterns, and frequencies. Most of the injuries occurred with unfavorable wind and weather conditions; 58% of them occurred in the start phase as the result of falls on uneven ground, on rocks, or trees; 10% during the flight phase as a result of turbulence or collisions with obstacles; and 32% during the landing phase, mainly by falling on the back from some height while landing too slowly, or by falling forward while landing too fast with back wind. As to the sites of the injuries, 60% were to the lower extremity, 26% to the upper extremity, and 14% to the body. The most serious injuries were fractures (42%), contusions (26%), ligamentous lesions (19%), luxations (6%), and deep wounds (6%). The most frequent injuries were ligamentous lesions and fractures of the upper ankle (14), spine contusions (5), radial fractures (4), knee contusions (4), hand fractures (3), calcaneus fractures (2) and shoulder luxations (2). We classed 56% of the injuries as mild, 42% as moderate, requiring subsequent operation or hospital treatment, and 1 as severe, with 2 months' hospital inpatient treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Specialty specific psychotherapy in internal medicine].

The establishment of a bio-psycho-social (monistic) approach to all problems of human health and disease is regarded as an essential prerequisite for the improvement of medical care. As a rule the special and functional pathology is on account of the psychotherapeutic approach enlarged by the "relation pathology" and adequate therapeutic techniques at this level. The associated with this increasing requirements on the social competence of the physician involve measures at the level of the medical education, to which psychotherapy and medical psychology have to contribute. This takes place in the framework of the particular integrative function of these specialties to render the psychosocial dimension methodically manageable for medicine. The state programmes for the method-related qualification in psychotherapy are a good basis for the integration of the psychosocial dimension into the practice of internal medicine. However, they need supplementation by measures in the pregraduate education.

Curriculum↗
PubMed1986

[Questionnaire for recording interpersonal value judgments in group psychotherapy].

Interpersonal estimation is a factor that is of importance to both the patient-therapeut relationship and the climate prevailing within the psychotherapy group. This contribution describes a questionnaire which permits interpersonal estimations in group psychotherapy to be expressed numerically. It enables identification of differences between the estimations given by different patients and also the patient's reception of other patient's estimations of himself. The questionnaire is used for weekly measurements of changes in connection with the diagnostic work accompanying group psychotherapy for neurotic maldevelopments.

Group Processes↗