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Biomedical subjects

M Vogt

Publications and source records attributed to M Vogt.

At least 37 records · Page 2Linked to original sources
PubMed2003

In vivo biomicroscopy of the skin with high-resolution magnetic resonance imaging and high frequency ultrasound.

Noninvasive imaging and characterization of the skin is of great interest in dermatology. In order to get relevant diagnostic information, high-resolution imaging techniques have to be applied. Ultrasonic imaging is a potential method for this purpose where the special requirements concerning the spatial resolution make it essential to apply high frequency ultrasound (HFUS). Alternatively, magnetic resonance imaging (MRI), being a very promising imaging modality, also shows the perspective of becoming a valuable diagnostic tool in dermatology. However, to account for the small dimensions of the structures under observation, very specialized system designs have to be developed. In this paper, a HFUS imaging system working in the 50 MHz and 100 MHz range is applied for high-resolution skin imaging. Furthermore, a commercial MRI-system was equipped with specially designed low noise rf (radio frequency) coils with minimized volume, and customized imaging sequences were applied to optimize the signal-to-noise ratio. With HFUS and high-resolution magnetic resonance (HR-MR) imaging complementary imaging techniques for in vivo biomicroscopy of the skin are available.

Artifacts↗
PubMed2002

[Studies on the importance of tick-borne encephalitis in Rhineland-Pfalz].

Within the scope of a prospective clinical study during 2001 in Rhineland-Palatinate specimen from sera and cerebrospinal fluids of 163 patients with suspected meningitis were controlled in an enzyme immunoassay concerning a TBE infection. Questionable results were checked via a neutralisation test. In no case such an infection was confirmed. No virus specific nucleic acids could be detected in 998 nymphs and adults of Ixodes ricinus in an additional investigation in 2000. Therefore Rhineland-Palatinate has to be considered as a region with low virus prevalence. A general recommendation for vaccination is not necessary.

Adolescent↗
PubMed2001

[72-year-old biker with transient hemisyndrome].

The primary diagnosis of a transient ischemic attack (TIA) in a 72-year-old healthy biker with a motoric aphasia, facial (oral branch) paresis and a mild weakness of the arm, hat to be specified after several exams. There was found a cardiogenic embolization of the common carotc artery with a new discovered paroxysmal atrial fibrillation. We describe our genera considerations, the exams and the conclusions.

Aged↗
PubMed2001

Hypoxia training for sea-level performance. Training high-living low.

It is widely accepted that prolonged exposure to extreme altitude is detrimental for exercise performance and muscle structure. Moreover, highly trained subjects seem to suffer more under hypoxic conditions than untrained people. When using hypoxia as an ergogenic stimulus in athletes, it has thus become customary to limit hypoxia exposure in terms of altitude and duration of exposure in order to achieve defined physiologic goals. If hypoxia application is limited to the duration of training sessions, specific hypoxia responses on the molecular level in skeletal muscle tissue can be demonstrated. Hypoxia inducible factor 1 (HIF-1alpha mRNA) is upregulated after 6 weeks of endurance training in hypoxia (equivalent to an altitude of 3850 m) in previously untrained subjects. This upregulation is independent of training intensity but not observed in subjects training under similar conditions in normoxia. High intensity training in hypoxia further results in an increase of vascular endothelial growth factor (VEGF) mRNA, capillarity and myoglobin mRNA. These results suggest that hypoxia training results in improvements of the oxygen transfer capacity in skeletal muscle tissue. They thus offer a plausible explanation for the observation that effects of hypoxia training in athletes can best be demonstrated when performance tests are carried out in hypoxia. Beneficial effects of "training high-living low" for sea level performance of athletes can be inferred from the structural changes observed in muscle tissue; however, the functional improvements remain to be demonstrated directly.

Altitude↗
PubMed2001

Rationale for endoscopic management of adenoma of the papilla of Vater: options and limitations.

BACKGROUND: Several studies and our own results prove that endoscopic therapy in selected cases of benign adenomas is safe and technically feasible. In patients refusing surgery or patients with high comorbidity and poor physical health status, endoscopic resection is an excellent alternative. DISCUSSION: The decision for endoscopic or surgical excision of adenomas is determined by general health status, histology, size, location, and depth of the lesion. In carcinoma of the papilla of Vater it is important to assess the tumoral ductal infiltration correctly to determine whether endoscopic resection is a viable option. Intraductal ultrasound is essential before initiating treatment and it therefore contributes to conservative therapy in patients with tumors of the papilla of Vater. Temporary placement of a short pancreatic duct stent may protect against pancreatitis and might allow more excessive ablation of adenomatous tissue, especially around the pancreatic duct orifice. After endoscopic sphincterotomy, biliary and pancreatic endoprostheses can be inserted easily in cases of obstructed pathways or cholangitis and pancreatitis due to tumor obstruction. Argon plasma coagulation can be used to treat oozing tumor hemorrhages or to vaporize tumoral residues after endoscopic snare resection. Endoscopic surveillance is essential after surgical or endoscopic resection of adenomas of the papilla of Vater.

Adenoma↗
PubMed2001

Pneumonia after cardiac surgery is predictable by tracheal aspirates but cannot be prevented by prolonged antibiotic prophylaxis.

BACKGROUND: The purpose of this study was to assess the value of tracheal aspirate as a predictor of pneumonia after coronary artery bypass grafting and to evaluate the efficacy of prolonged perioperative antibiotic prophylaxis. METHODS: Tracheal aspirates of 500 patients undergoing coronary artery bypass grafting were taken immediately after intubation and analyzed for microorganisms by Gram stain and semiquantitative microbiologic cultures. All patients received 2 g ceftriaxone as a single-dose perioperative antibiotic prophylaxis before operation. Results of Gram stains were available before the patients were transferred to the intensive care unit. After the results were known, both groups of patients (positive Gram stain, group 1; negative Gram stain, group 2) were randomly assigned to either conventional antibiotic prophylaxis (A), consisting of ceftriaxone 2 g on postoperative day 1, or prolonged antibiotic prophylaxis (B), with ticarcillin + clavulanic acid 3 x 5.2 g during 72 hours. RESULTS: From 500 patients, 91 had a positive Gram stain whereas 409 had a negative one. The incidence of pneumonia was significantly higher in patients with preoperative positive tracheal aspirates (15.3%) than in patients with a negative one (3.6%; p < 0.01). However, prolonged prophylaxis did not reduce the rate of postoperative pneumonia, which was as high as 13% in untreated positive patients versus 17% in treated positive patients, and 2% in untreated negative patients versus 4% in treated patients. In patients who had pneumonia, there was a high correlation between the microorganisms found in preoperative aspirates and those observed when aspirates were repeated (100% correlation in patients with conventional antibiotic prophylaxis and 87% in those with prolonged prophylaxis). CONCLUSIONS: Early postoperative pneumonia (<7 days) is most likely caused by microorganisms that colonize the respiratory tract before operation. The risk of pulmonary infection after coronary artery bypass grafting can be predicted from the preoperative tracheal aspirates. Prolonged perioperative antibiotic prophylaxis has no efficacy in reducing the incidence of pulmonary infections.

Aged↗
PubMed2001

Postprandial blood glucose latency after oatmeal is a valid screening test for diabetic gastropathy in type 1 diabetes, but not in type 2 diabetes.

Disordered gastric motility occurs frequently in diabetes mellitus. Gastric emptying time is abnormal in about 50% of diabetic patients and delayed emptying time is known as an important cause for brittle diabetes in type 1 diabetes. We compared the rise in blood glucose after a standardized meal (oatmeal test) as a noninvasive screening test for diabetic gastropathy with the noninvasive measurement of gastric emptying time with ultrasound in type 1 and type 2 diabetic patients. The test result was considered pathological if the rise of blood glucose after an initial steady state did not reach 20 mg/dl in the first 20 min after the meal (prolonged blood glucose latency). We found a sensitivity of 90% (58.7-99.8) and a specificity of 100% (71.5-100) for the oatmeal test in type 1 diabetes in the gastropathy screening. In type 2 diabetes we found a sensitivity of 13% (1.5-38.3) and a specificity of 78% (60-90.7) (95% CI). In conclusion, the oatmeal test seemed to be a good, noninvasive screening test in diabetic gastropathy in type 1 diabetes, but has no diagnostic value in type 2 diabetes. The causes for such a difference may be due to a different postprandial blood glucose regulation in type 2 diabetes compared to the beta-cell-depleted type 1 diabetes.

Adult↗
PubMed2001

Training high--living low: changes of aerobic performance and muscle structure with training at simulated altitude.

This study was undertaken to test the hypothesis that endurance training in hypoxia is superior to training of the same intensity in normoxia. To avoid adaptation to hypoxia, the subjects lived under normoxic conditions when not training. A secondary objective of this study was to compare the effect of high- vs. moderate-intensity training on aerobic performance variables. Thirty-three men without prior endurance training underwent a cycle ergometer training of 6 weeks, 5 d/week, 30 minutes/d. The subjects were assigned to 4 groups, N-high, N-low, H-high and H-low based on the training criteria normoxia (N; corresponding to a training altitude of 600 m), vs. hypoxia (H; training altitude 3850 m) and intensity (high; corresponding to 80% and low: corresponding to 67% of VO2max). VO2max measured in normoxia increased between 8.5 to 11.1%, independent of training altitude or intensity. VO2max measured in hypoxia increased between 2.9 and 7.2%. Hypoxia training resulted in significantly larger increases than normoxia training. Maximal power that subjects could maintain over a thirty-minute period (measured in normoxia or hypoxia) increased from 12.3 - 26.8% independent of training altitude. However, subjects training at high intensity increased performance more than subjects training at a low intensity. Muscle volume of the knee-extensors as measured by magnetic resonance imaging increased significantly in the H-high group only (+ 5.0%). Mitochondrial volume density measured by EM-morphometry in biopsy samples of m. vastus lat. increased significantly in all groups with the highest increase seen in the H-high group (+ 59%). Capillary length density increased significantly in the H-high group only (+ 17.2%). The main finding of this study is that in previously untrained people, training in hypoxia while living at low altitude increases performance in normoxia to the same extent as training in normoxia, but leads to larger increases of aerobic performance variables when measured under hypoxic conditions. Training intensity had no effect on the gain of VO2max. On the level of skeletal muscle tissue, the combination of hypoxia with high training intensity constitutes the most effective stimulus for increasing muscle oxidative capacity.

Acclimatization↗
PubMed2001

Molecular adaptations in human skeletal muscle to endurance training under simulated hypoxic conditions.

This study was performed to explore changes in gene expression as a consequence of exercise training at two levels of intensity under normoxic and normobaric hypoxic conditions (corresponding to an altitude of 3,850 m). Four groups of human subjects trained five times a week for a total of 6 wk on a bicycle ergometer. Muscle biopsies were taken, and performance tests were carried out before and after the training period. Similar increases in maximal O(2) uptake (8.3-13.1%) and maximal power output (11.4-20.8%) were found in all groups. RT-PCR revealed elevated mRNA concentrations of the alpha-subunit of hypoxia-inducible factor 1 (HIF-1) after both high- (+82.4%) and low (+78.4%)-intensity training under hypoxic conditions. The mRNA of HIF-1alpha(736), a splice variant of HIF-1alpha newly detected in human skeletal muscle, was shown to be changed in a similar pattern as HIF-1alpha. Increased mRNA contents of myoglobin (+72.2%) and vascular endothelial growth factor (+52.4%) were evoked only after high-intensity training in hypoxia. Augmented mRNA levels of oxidative enzymes, phosphofructokinase, and heat shock protein 70 were found after high-intensity training under both hypoxic and normoxic conditions. Our findings suggest that HIF-1 is specifically involved in the regulation of muscle adaptations after hypoxia training. Fine-tuning of the training response is recognized at the molecular level, and with less sensitivity also at the structural level, but not at global functional responses like maximal O(2) uptake or maximal power output.

Acyl-CoA Dehydrogenase↗
PubMed2001

Muscle tissue adaptations to hypoxia.

This review reports on the effects of hypoxia on human skeletal muscle tissue. It was hypothesized in early reports that chronic hypoxia, as the main physiological stress during exposure to altitude, per se might positively affect muscle oxidative capacity and capillarity. However, it is now established that sustained exposure to severe hypoxia has detrimental effects on muscle structure. Short-term effects on skeletal muscle structure can readily be observed after 2 months of acute exposure of lowlanders to severe hypoxia, e.g. during typical mountaineering expeditions to the Himalayas. The full range of phenotypic malleability of muscle tissue is demonstrated in people living permanently at high altitude (e.g. at La Paz, 3600-4000 m). In addition, there is some evidence for genetic adaptations to hypoxia in high-altitude populations such as Tibetans and Quechuas, who have been exposed to altitudes in excess of 3500 m for thousands of generations. The hallmark of muscle adaptation to hypoxia in all these cases is a decrease in muscle oxidative capacity concomitant with a decrease in aerobic work capacity. It is thought that local tissue hypoxia is an important adaptive stress for muscle tissue in exercise training, so these results seem contra-intuitive. Studies have therefore been conducted in which subjects were exposed to hypoxia only during exercise sessions. In this situation, the potentially negative effects of permanent hypoxic exposure and other confounding variables related to exposure to high altitude could be avoided. Training in hypoxia results, at the molecular level, in an upregulation of the regulatory subunit of hypoxia-inducible factor-1 (HIF-1). Possibly as a consequence of this upregulation of HIF-1, the levels mRNAs for myoglobin, for vascular endothelial growth factor and for glycolytic enzymes, such as phosphofructokinase, together with mitochondrial and capillary densities, increased in a hypoxia-dependent manner. Functional analyses revealed positive effects on V(O(2)max) (when measured at altitude) on maximal power output and on lean body mass. In addition to the positive effects of hypoxia training on athletic performance, there is some recent indication that hypoxia training has a positive effect on the risk factors for cardiovascular disease.

Acclimatization↗
PubMed2000

Diffusion in Pseudomonas aeruginosa biofilms: a pulsed field gradient NMR study.

A Pseudomonas aeruginosa biofilm is studied with pulsed field gradient echo nuclear magnetic resonance. Although not all spectral components are assigned yet, the experimental results show that a biofilm consists of components with very different diffusion coefficients. The various biofilm components that give motionally narrowed 1H NMR signals, can be grouped into five classes with diffusion coefficients, ranging from 2 x 10(-9) to 1 x 10(-13) m2 s-1. Investigation of the diffusion behavior of water in the biofilm shows three fractions with different diffusion coefficients. Besides the highly mobile bulk water at least two other fractions with much lower diffusion coefficients are detected. It is shown that one of the fractions with the low diffusion coefficient probably arises from intracellular water. Also for another component of the biofilm, glycerol, three fractions with diffusion coefficients that differ more than a factor ten are detected. Also a group of signals exists which result from practically immobile components.

Alginates↗
PubMed2000

[75-year-old man with rapid deterioration of his general condition].

A 75 year old man was hospitalized because of rapid deterioration of his general condition, weight loss, night sweat and subfebrile temperature. The patient presented with severely reduced general condition, tachyarrythmia with previously known atrial fibrillation. Laboratory investigations revealed among others a moderately increased CRP-value, normal sedimentation rate and, initially, a normal white cell count. The differential diagnosis included neoplastic and infectious diseases (i.e. endocarditis, tuberculosis), endocrinopathies (i.e. thyreoditis) and general inflammatory or rheumatic diseases. An initially increased CMV-IgM-titer, a rising anti CMV IgG-titer and gradually developing atypical lymphocytosis in particular suggested diagnosis of severe CMV-infection. The diagnosis was confirmed by PCR positive for CMV-DNA in blood. The course of a CMV-primary infection may develop from asymptomatic infection over a mononucleosis-like syndrome to disseminated CMV-infection with multi organ involvement.

Aged↗
PubMed2000

Repair of interrupted aortic arch: results after more than 20 years.

BACKGROUND: This study focused on the influence of concomitant anomalies, the individual surgical approach, and the probability for reinterventions. METHODS: Between 1975 and 1999, 94 patients with interrupted aortic arch were evaluated for short- and long-term results after surgical treatment. RESULTS: Interrupted aortic arch was associated mainly with a ventricular septal defect (85%) and left ventricular outflow tract obstruction (LVOTO, 13%). Mean follow-up was 6.7 years (median 6.9 years, 628.4 patient years). A single-stage operation was performed in 76 cases. Early mortality for two-stage procedures was 37% and late mortality was 26%, compared with single-stage procedures, with an early mortality of 12% and a late mortality of 20%, respectively. Early mortality in patients with additional LVOTO was 42% and late mortality was 50%. Freedom from reoperation at 5 years was 62%, and at 10 years was 49%. Reinterventions were performed mainly for residual arch stenosis, also with bronchus or tracheal compression, or LVOTO. CONCLUSIONS: Arch continuity and repair of associated anomalies can be achieved with an acceptable overall risk in this often complex entity. Associated anomalies play an important role in the outcome. Single-stage repair with primary anastomosis of the arch should be the surgical goal. The long-term probability for reoperation is high.

Adolescent↗
PubMed2000

Intracardiac thrombus formation after the Fontan operation.

OBJECTIVES: Intracardiac thrombus formation is suspected to be a specific sequela after the Fontan operation and is difficult to determine by means of routine transthoracic echocardiography. The aim of our study was to evaluate the occurrence of intracardiac thrombi in the different types of Fontan modifications and to identify predisposing risk factors. METHODS: We evaluated 52 patients who had undergone a Fontan-type operation and were free of symptoms regarding thrombosis as determined by transesophageal echocardiography. RESULTS: In 17 (33%) patients thrombus formation could be found without clinical evidence of thromboembolic complications. Neither underlying morphologic disease nor age at operation, type of Fontan operation, sex, follow-up interval, arrhythmias, or laboratory or hemodynamic findings could be identified as predisposing risk factors. CONCLUSION: In patients having had a Fontan operation with inadequate or without anticoagulation medication, we would recommend routine transesophageal echocardiography to exclude eventual thrombi. Because of the high incidence of thrombi, we suggest oral anticoagulation therapy in all patients.

Adolescent↗
PubMed2000

Endoscopic therapy of adenomas of the papilla of Vater. A retrospective analysis with long-term follow-up.

AIMS: To compare the efficacy and the complication rate between endoscopic snare resection of adenomas of Vater's papilla and endoscopic palliation. METHODS: In a retrospective, non randomized manner, we compared long-term results of our endoscopic strategies in 36 patients with histologically confirmed adenoma of Vater's papilla submitted either to local endoscopic snare resection (n=18) or to simple endoscopic palliation (n= 18), respectively. RESULTS: Between 1985 and 1998 results were reviewed. Median age was 76.5 (range 42-89) years in the palliation, and 64.0 (23-89) years in the endoscopic snare resection group. Median duration of follow-up was 33 (6-135) and 75.0 (27-123) months, respectively. The incidence of adenocarcinoma of Vater's papilla was 1 per 52.8 patient-years after endoscopic snare resection and 1 per 15.5 patient-years in the group treated with endoscopic palliation. Compared to the results of endoscopic palliation (prosthesis, sphincterotomy), we found a significant reduction of carcinoma-related death (p=0.0045, McNemar) and adenoma carcinoma-sequence (p=0.007, McNemar) after snare resection. CONCLUSIONS: This retrospective study suggests that complete endoscopic snare resection of adenomas of Vater's papilla will lead to a lower rate of adenoma-carcinoma sequence, to a lower carcinoma-related death rate and probably improves patient survival. These results should be proven prospectively.

Adenocarcinoma↗