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Biomedical subjects

M Vogt

Publications and source records attributed to M Vogt.

At least 19 recordsLinked to original sources
PubMed2005

[Comparison of chromosomal defects in primary tumor and metastases by comparative genomic hybridization (CGH)].

Molecular methods can complement the classical methods in pathology like macroscopic, histological and immunohistochemical examinations.Comparative genomic hybridization is a cytogenetic method to screen for gains and losses of chromosomal material in tumor cells. This method allows defect studies of archival paraffin-embedded and formalin-fixed tumor material. CGH can detect gains and losses of chromosomal material that are at least 10 to 20 megabases in size. This genome-wide screening method allows to study the cytogenetic relationship between differently located tumors of a patient. To answer the question if these different tumors are metastases of the primary lung tumor or independent primary tumors CGH analysis is a supplementary method that introduces new prospectives.

Chromosome Aberrations↗
PubMed2004

Prevalence and risk factors of hepatitis C infection after cardiac surgery in childhood before and after blood donor screening.

BACKGROUND: Since 1974, the risk of acquiring non-A non-B hepatitis by blood transfusion is well known. In 1999, children having had polytransfusions (group 1) after cardiac surgery prior to the establishment of routine blood donor screening could be identified as a risk group for hepatitis C (HCV) infection. PATIENTS AND METHODS: In 1991, Germany began screening blood donors for hepatitis C. To describe the risk after the implementation of blood donor screening, we studied 211 children (group 2) having had open heart surgery after 1991 and compared prevalence for anti-HCV antibodies and known risk factors to group 1. RESULTS: None of the 211 patients with cardiac surgery after 1991 had detectable anti-HCV antibodies, compared to 67 of the 458 patients (14.6%) of group 1 (p < 0.001). The mean number of operations in both groups was virtually the same (mean 1.7 +/- 0.9 in group 1, mean 1.6 +/- 0.9 in group 2, p = 0.075), whereas the total number of blood products per patient differed significantly (group 1 mean 8 +/- 17.6, group 2 mean 3.5 +/- 2.8; p < 0.001). Multivariate analysis of risk factors demonstrates affiliation to group 1, transfusion of fresh blood, warm whole blood, heparinized blood (p < 0.001) and plasma (p = 0.004) as significant. CONCLUSION: After the implementation of blood donor screening, the risk for HCV infection after cardiac surgery in childhood dropped significantly from 14.6% to < 0.5%. These data show the necessity of HCV screening for patients at risk (operations before 1991) and do not favor a general screening for all patients.

Adolescent↗
PubMed2003

[Effect of hypoxia on muscular performance capacity: "living low--training high"].

Altitude training is very popular among endurance athletes. But athletes respond very different on acute altitude exposure and altitude training. There are individual differences in the decrement of maximal oxygen consumption making general advices on the effect of altitude training very difficult. During the last few years different altitude training regimes have been developed. Beside "living high--training low," the concept of "living low--training high" becomes more and more popular. By this regime, athletes train under simulated or natural hypoxic conditions, while recovery time is spent at sea-level. Several studies show that with "living low--training high" maximal oxygen consumption as well as aerobic and anaerobic endurance performance can be improved. Molecular analysis reveal that a transcription factor called Hypoxia-Inducible Factor 1 (HIF-1) acts as a master gene in the regulation of hypoxia-dependent gene expression. In human skeletal muscle "living low-training high" induces the expression of glycolytic enzymes, the angiogenic factor VEGF, myoglobin as well as the increase of capillarity and mitochondrial content in parallel to the induction of the HIF-1 system. In trained human skeletal muscle, these adaptations cause a shift of substrate selection to an increased oxidation of carbohydrates as well as to an improvement of the conditions for transport and utilization of oxygen. Depending on the kind of sports, "living low--training high" can be used to train these muscular adaptations and to increase exercise performance.

Acid-Base Equilibrium↗
PubMed2003

The response of trained athletes to six weeks of endurance training in hypoxia or normoxia.

This study was performed to investigate the effect of training under simulated hypoxic conditions. Hypoxia training was integrated into the normal training schedule of 12 endurance trained cyclists. Athletes were randomly assigned to two groups and performed three additional training bouts per week for six weeks on a bicycle ergometer. One group (HG) trained at the anaerobic threshold under hypoxic conditions (corresponding to an altitude of 3200 m) while the control group (NG) trained at the same relative intensity at 560 m. Preceding and following the six training weeks, performance tests were performed under normoxic and hypoxic conditions. Normoxic and hypoxic .VO2max, maximal power output as well as hypoxic work-capacity were not improved after the training period. Testing under hypoxic conditions revealed a significant increase in oxygen saturation (SpO 2, from 67.1 +/- 2.3 % to 70.0 +/- 1.7 %) and in maximal blood lactate concentration (from 7.0 to 9.1 mM) in HG only. Ferritin levels were decreased from 67.4 +/- 16.3 to 42.2 +/- 9.5 microg/l (p < 0.05) in the HG and from 54.3 +/- 6.9 to 31.4+/- 8.0 microg/l (p = 0.17) in the NG. Reticulocytes were significantly increased in both groups by a factor of two. In conclusion, the integration of six weeks of high intensity endurance training did not lead to improved performance in endurance trained athletes whether this training was carried out in hypoxic or normoxic conditions.

Adult↗
PubMed2003

Comparison of high frequency ultrasound and optical coherence tomography as modalities for high resolution and non invasive skin imaging.

High frequency ultrasound (HFUS) and optical coherence tomography (OCT) are techniques for high resolution imaging of tissues. The penetration depth of these modalities is limited, but it is sufficiently large enough for non invasive skin imaging. HFUS and OCT are based on the same concept. Waves (ultrasonic waves, respectively light waves) propagate along a narrow beam, are backscattered at tissue inhomogeneities and analyzed over time of flight to obtain spatially resolved morphological information. The objective of this paper is to compare HFUS and OCT in terms of resolution, dynamic range and contrast and to assess their value as tools for high resolution skin imaging. Measurements on phantoms and in vivo have been performed with a 100 MHz ultrasound system and an OCT-scanner working in the near infrared spectrum at 1300 nm wave-length. From the measurements, it can be concluded that OCT delivers an almost isotropic resolution (axial resolution about 5.8 microns, lateral resolution about 4.1 microns), whereas the resolution of the investigated HFUS system is more anisotropic (axial resolution about 9.3 microns, lateral resolution about 60 microns). HFUS and OCT show different penetration depths and a different contrast. Both techniques can, therefore, be combined advantageously in a multimodality approach to account for their individual characteristics.

Hair↗
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↗