Biomedical subjects

Frank Weber

Publications and source records attributed to Frank Weber.

65 records · Page 4Linked to original sources

PubMed2003

Medical risk factors in fatal military aviation crashes: a case-control study.

BACKGROUND: Periodic medical examinations are the daily work of the flight surgeon. Their immediate impact on flight safety, however, has not been evaluated. This case-control study was done to ascertain whether, among German military pilots, differences exist in the results of periodic medical examinations that were associated with a higher odds of being involved in a fatal aircraft mishap. METHODS: Participants were 146 German military pilots who died in air crashes and 292 controls. Cases and controls were matched 1:2 by aeronautical confounders (age, type of aircraft aeronautical experience, and membership in the air force, army, or navy). Data source was the central register of the German Air Force Institute of Aviation Medicine; data were obtained from periodic medical examinations and included physical examination and laboratory data. Odds ratios were calculated by conditional logistic regression analysis. RESULTS: Descriptive statistics showed no distinct difference between cases and controls in most of the parameters considered except for total serum bilirubin, but multiple conditional logistic regression showed no remarkably different odds for any of the parameters tested. CONCLUSION: In aircrew who pass all the criteria for fitness to fly there are no important medical risk factors for fatal air crashes that can be detected by periodic medical examinations.

Accidents, Aviation↗

PubMed2003

[Cerebrospinal fluid filtration as experimental therapy in therapy refractory psychoses in Borna disease virus seropositive patients. Therapeutic effects, findings].

According to previous investigations, mild Borna disease virus encephalitis may underlie a subgroup of affective or schizophrenic type psychoses. And virus-induced immune pathology may underlie even a larger subgroup of psychoses. We treated BDV seropositive patients suffering from therapy resistant schizophrenic or affective spectrum psychoses by cerebrospinal fluid filtration (CSFF) in an experimental add-on treatment. CSFF was shown previously to be an effective immune modulatory treatment in autoimmune neurological disease, Guillain-Barré syndrome. CSFF appears to be an effective treatment in therapy resistant psychosis also, but only 4 patients were treated yet.

Antibodies, Viral↗

PubMed2002

Risk factors for subclinical carotid atherosclerosis in healthy men.

BACKGROUND AND OBJECTIVE: Ultrasound-detected carotid artery intima-media thickness (IMT) is regarded as a valid index of atherosclerosis. Cross-sectional studies have been helpful in establishing determinants of IMT, but the long-term relationship between cardiovascular risk factors and subclinical atherosclerosis in a low-risk population has not been thoroughly evaluated. METHODS: A cohort of 483 military aviators, officially considered as fit for flying and therefore normotensive, was included in the study. All subjects underwent baseline examination with measurement of cardiovascular risk factors (body mass index, blood pressure, physical working capacity, cigarette smoking, and levels of cholesterol, high-density lipoprotein cholesterol, triglycerides, and gamma-glutamyltransferase) and carotid ultrasonography at the end point after 10 years of follow-up. RESULTS: Age, cigarette smoking, and blood pressure were independent long-term predictors of IMT. After adjustment for age, cigarettes smoked daily at baseline, categorized in units of five cigarettes each (regression coefficient in mm, 0.057 [95% CI: 0.029 to 0.085]; p < 0.0001), and systolic blood pressure (regression coefficient in mm, 0.007 [95% CI: 0.003 to 0.010], p < 0.0001) were the only predictors of IMT. Physical working capacity was not associated with IMT. CONCLUSION: Even in normotensive individuals, systolic blood pressure is a strong predictor of early carotid atherosclerosis.

Aviation↗

PubMed2002

Interferon-beta-1b increases serum interleukin-12 p40 levels in primary progressive multiple sclerosis patients.

Serum levels of interleukin-12 heterodimer (IL-12p70) and its homodimeric subunit (IL-12p40) were analyzed by enzyme-linked immunosorbent assay in 18 patients with primary progressive multiple sclerosis (MS) during 3 months before and 3 months under treatment with interferon-beta-1b (IFNbeta-1b, Betaferon(), eight million units (MIU) every other day subcutaneously). Median IL-12p40 levels in MS patients before treatment (66.5 and 63.9 pg/ml) were not elevated compared to 18 healthy controls. IL-12p40 significantly increased during treatment (P<0.0001, median 105.3 pg/ml after 1 month and 95.3 pg/ml after 3 months). Detectable serum levels of IL-12p70 before therapy were only found in one patient. IL-12p70 did not increase during treatment. These data show that immunological processes may also play a role in primary progressive MS and that IFNbeta-1b has an immunomodulating effect in this particular MS subtype.

Adjuvants, Immunologic↗

PubMed2002

Structural plasticity and noncovalent substrate binding in the GroEL apical domain. A study using electrospay ionization mass spectrometry and fluorescence binding studies.

Advances in understanding how GroEL binds to non-native proteins are reported. Conformational flexibility in the GroEL apical domain, which could account for the variety of substrates that GroEL binds, is illustrated by comparison of several independent crystallographic structures of apical domain constructs that show conformational plasticity in helices H and I. Additionally, ESI-MS indicates that apical domain constructs have co-populated conformations at neutral pH. To assess the ability of different apical domain conformers to bind co-chaperone and substrate, model peptides corresponding to the mobile loop of GroES and to helix D from rhodanese were studied. Analysis of apical domain-peptide complexes by ESI-MS indicates that only the folded or partially folded apical domain conformations form complexes that survive gas phase conditions. Fluorescence binding studies show that the apical domain can fully bind both peptides independently. No competition for binding was observed, suggesting the peptides have distinct apical domain-binding sites. Blocking the GroES-apical domain-binding site in GroEL rendered the chaperonin inactive in binding GroES and in assisting the folding of denatured rhodanese, but still capable of binding non-native proteins, supporting the conclusion that GroES and substrate proteins have, at least partially, distinct binding sites even in the intact GroEL tetradecamer.

Binding Sites↗

PubMed2002

The endogenous pentapeptide QYNAD induces acute conduction block in the isolated rat sciatic nerve.

Reversible block of sodium channels by endogenous substances was claimed to account for the fast relapses and remissions seen in demyelinating autoimmune disorders. The pentapeptide QYNAD, isolated from the cerebrospinal fluid from patients with multiple sclerosis (MS), blocked Na+ channels in various types of cultured cells. We show that 100 microM QYNAD bath-applied to isolated rat sciatic nerve causes the amplitude and area of the compound nerve action potential to decrease by 30-40%, while the latency increases. Wash-out reverses the changes in part. This suggests that QYNAD may indeed contribute to the fast symptom changes in MS and related diseases.

Action Potentials↗

PubMed2002

Axonal neuropathy in chronic peripheral arterial occlusive disease.

Chronic peripheral arterial occlusive disease of the lower limbs may cause tissue damage. Type and extent of peripheral nerve involvement is controversial. We examined 25 patients with peripheral arterial occlusive disease in various grades of severity and 37 age-matched healthy controls using conventional angiography and motor and sensory nerve conduction tests. Subjects with confounding factors for peripheral neuropathies were excluded. We found prolongation of distal motor latencies, decrease of motor and sensory nerve conduction velocities, and reduction in amplitude of the compound muscle action potential. Amplitudes of the compound muscle action potentials were lower in patients with pain at rest than in patients with intermittent claudication and decreased with increasing neurological disability score. Sural nerve conduction velocity, peroneal nerve F-wave chronodispersion, and tibial nerve F-wave persistence were the most frequent abnormal findings. Therefore we concluded that chronic peripheral arterial occlusive disease causes axonal degeneration, resulting in axonal polyneuropathy.

Adult↗

PubMed2002

Routine electroencephalograms of pilots later killed in crashes: a case-control study.

BACKGROUND: The value of the electroencephalogram (EEG) as a screening tool in aviation medicine is subject to debate. We evaluated the use of periodic repetition of the EEG--after an initial EEG screening-in healthy, fully-licensed pilots to identify risk factors for fatal air crashes. METHODS: In a nested case-control study, we compared the EEG patterns of 33 pilots who died in military aviation accidents from 1990 to 2001 with the recordings of 66 controls. Cases and controls were matched for potentially confounding factors such as age, military membership, type of aircraft, and aeronautical experience. RESULTS: Both groups presented normal EEGs. EEG findings in cases and controls did not differ; nonspecific EEG abnormalities did not occur more frequently in those pilots who crashed. CONCLUSIONS: After an initial EEG screening, periodic repetition of the EEG is not a useful means to detect risk for fatal air crashes.

Accidents, Aviation↗

PubMedDate not supplied

Major bile duct injuries after laparoscopic cholecystectomy: a tertiary center experience.

Bile duct injury is a severe and potentially life-threatening complication of laparoscopic cholecystectomy. Several series have described a 0.5% to 1.4% incidence of bile duct injuries during laparoscopic cholecystectomy. The aim of this study was to report on an institutional experience with the management of complex bile duct injuries and outcome after surgical repair. Data were collected prospectively from 40 patients with bile duct injuries referred for surgical treatment to our center between April 1998 and December 2003. Prior to referral, 35 patients (87.5%) underwent attempts at surgical reconstruction at the primary hospital. In 77.5% of the patients, complex type E1 or type E2 BDI was found. Concomitant with bile duct injury, seven patients had vascular injuries. Roux-en-Y hepaticojejunostomy was carried out in 33 patients. In two patients, Roux-en-Y hepaticojejunostomy and vascular reconstruction were necessary. Five patients, one with primary nondiagnosed Klatskin tumor, required right hepatectomy. Two patients, both with bile duct injuries and vascular damage, died postoperatively. Because of progressive liver insufficiency, one of them was listed for high-urgency liver transplantation but died prior to intervention. At the median follow-up of 589 days, 82.5% of the patients are in excellent general condition. Seven patients have signs of chronic cholangitis. Major bile duct injuries remain a significant cause of morbidity and even death after laparoscopic cholecystectomy. Because they present a considerable surgical challenge, early referral to an experienced hepatobiliary center is recommended.

Adult↗

PubMedDate not supplied

Emergency stent-graft placement in thoracic aortic dissection and evolving rupture.

BACKGROUND: Even with rapid diagnosis and effective medical treatment mortality in type B aortic dissection with evidence of extraaortic leakage of blood remains high. Considering a mortality rate of 29% to 50% associated with emergency surgical repair, the concept of endovascular stent-graft placement may become a life-saving option in impending or evolving rupture by endovascular sealing of the entry tear and subsequent abortion of leakage. METHODS: The concept was tested by comparing short-term and 1-year outcomes of 11 patients after emergency endovascular stent-graft placement with historic-matched control patients subjected to conventional therapy. All patients had acute type B dissection complicated by loss of blood into periaortic spaces. RESULTS: Emergency stent-graft placement was successful without periprocedural morbidity, aborted leakage, and ensured reconstruction of the dissected aorta; at a mean follow-up of 15 +/- 6 months no death had occurred in the stent-graft group whereas four patients had died with conventional treatment (p < 0.05). CONCLUSION: With appropriate logistics and expertise, type B aortic dissection with leakage and evolving rupture may benefit from nonsurgical reconstruction of the dissected segment by endovascular stent grafts.

Acute Disease↗

PubMedDate not supplied

[The incidence of agglutination and its influence on sperm quality and fertility of boar semen].

The aim of this study was to examine the incidence of sperm agglutinations and their relationships with sperm quality and fertility. Semen samples of 40 boars of an AI-station were investigated. Nineteen of the 40 investigated boars showed a constantly low (< 10% agglutinated sperm), 3 an intermediate (10-20%) and 6 boars a high level (> 20%) of agglutination in raw semen. The degree of agglutination in sperm samples of 12 boars varied distinctly during the investigation period. During summer more (P < 0.05) agglutinated sperm were observed (11.0 +/- 11.6%) than during winter (6.2 +/- 7.3%). There was no association between bacterial contamination and incidence of agglutinations (P > 0.05). After dilution in extender the percentage of agglutinated sperm decreased from 6.2 +/- 7.3% to 1.1 +/- 1.4% (P < 0.0001). Twenty-four hours after dilution the percentage of progressively motile sperm was 7.4% lower (P < 0.05) in ejaculates with an initially high degree of agglutination (> 20% agglutinated sperm) compared to samples with an initially low degree of agglutinated sperm (< 10%). Plasma membrane integrity, mitochondrial membrane potential, acrosome reaction and chromatin structure were independent (P > 0.05) from the level of agglutination. Fertility data did not differ (P > 0.05) between boars with low and high numbers of agglutinated sperm in raw semen. The results show that there are individual, ejaculatory and seasonal variations in the incidence and degree of agglutination. Agglutinations have a negative effect on motility of sperm and disappear to a large extent after dilution in sperm extender. They have no negative consequences on fertility.

Animals↗