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Biomedical subjects

S Weber

Publications and source records attributed to S Weber.

At least 163 records · Page 9Linked to original sources
PubMed1997

[Bacillus cereus pneumonia after thoracic trauma. Case report and review of the literature].

We report on the case of a pneumonia caused by Bacillus cereus in a patient who sustained severe thoracic trauma, fractures of ribs 3-12, left lung contusion and haematopneumothorax. Bronchoscopic alveolar lavage (BAL) performed on ICU day four helped identifying the underlying cause of pneumonia. Inspite of early diagnosis and antibiotic treatment with clindamycin, cefotaxim and tobramycin, which rapidly eliminated the bacteria from the patient's lungs, the patient eventually died from the severe underlying injuries. However, this case emphasises that early performed BAL and rapid microbiological staining techniques can help diagnose pneumonia in critically ill patients. We also review the literature on pulmonary infections caused by Bacillus cereus.

Adult↗
PubMed1997

Osteochondrosis dissecans of the lateral femoral condyle before skeletal maturity.

Many surgical techniques are available for the treatment of osteochondrosis dissecans before skeletal maturity with variable success. In this paper we present a simple and safe surgical technique of bone grafting and temporary stabilization. The rare case of a 10-year-old boy, who suffered from a large developing osteochondrosis dissecans of the lateral femoral condyle, is reported. This patient was treated by retrograde autologous bone graft and fixation of the fragment with K-wires. After 4 weeks partial weight-bearing was possible. During 5 months the lesion healed well which could be demonstrated by x-ray and MRI. Consequently, the K-wires were removed. Because there is a high risk of osteoarthritis developing in the weight-bearing areas, especially in large lateral lesions, prophylactic stabilization and bone grafting is suggested. This can be performed successfully by the demonstrated simple technique.

Bone Transplantation↗
PubMed1997

Cost-effectiveness of hepatitis A vaccination in healthcare workers.

OBJECTIVE: To study the cost-effectiveness of vaccination for hepatitis A. SETTING: Hypothetical analysis of students currently enrolled in medical school in the United States. METHOD: A Markov-based model was developed using data from the literature, actual hospital costs, and an annual discount rate of 5%. The incidence rate was based on the lowest annual rate for the US population during the past decade. RESULTS: Over the lifetimes of students currently in medical school, the model estimated that there would be 286 hepatitis A cases with four deaths and 107 lost years of life. With routine vaccination, these numbers would decrease to 17, 0.3, and 6, respectively. The costs per life-year saved and quality adjusted life-year saved were $58,000 and $47,000, respectively. Serologic screening prior to vaccination was less cost-effective than universal vaccination. If the incidence of hepatitis A was underestimated by a factor of 5, the cost per life-year saved would decrease to $5,500. If the incidence of hepatitis was underestimated by a factor of 10, vaccination would result in a net cost savings. CONCLUSION: We conclude that the cost per life-year saved by routine hepatitis A vaccination was similar to many other standard medical modalities. For routine vaccination of medical students to be cost-saving, the incidence rate for hepatitis A must be at least 10 times higher than the rate presently reported for the general population. Serological screening prior to vaccination was not cost-effective.

Adult↗
PubMed1997

Evaluation of metastases and reactive lymph nodes in Doppler sonography using an ultrasound contrast enhancer.

RATIONALE AND OBJECTIVES: The authors conducted a prospective study in D-galactose signal-enhanced Doppler sonography of lymph nodes to investigate new aspects in differentiating malignant from reactive lymph nodes of patients with suspected malignancy of the neck. METHODS: Twenty-one patients with suspected squamous epithelial cell carcinoma metastases of the neck were examined by Doppler sonography before and after administration of an ultrasound signal-enhancing agent, consisting of D-galactose microbubbles. Qualitative sonomorphology, peak flow rates, and pulsatility and resistive indices were assessed. RESULTS: Compared with conventional Doppler, enhanced Doppler sonography gave detailed additional information about vascularization of metastases or reactive lymph nodes. Signal-enhanced Doppler of metastases showed a relatively characteristic pattern of vascularity, therefore facilitating differential diagnoses and allowing better discrimination from surrounding tissue, demonstrated by the infiltration of neighboring vessels in the neck. Concerning reactive lymph nodes, vascularization could be stated and measured in many cases only after signal enhancement. Evaluating peak velocities and pulsatility and resistive indices could not differentiate significantly malignant from reactive lymph nodes. CONCLUSIONS: Administration of a D-galactose-based signal-enhancer helps to differentiate malignant from reactive lymph nodes of the neck. It is superior to conventional Doppler by improving evaluation of the vascularity and could be of use for staging procedures.

Aged↗
PubMed1997

The design of an animal PET: flexible geometry for achieving optimal spatial resolution or high sensitivity.

We present the design of a positron emission tomograph (PET) with flexible geometry dedicated to in vivo studies of small animals (TierPET). The scanner uses two pairs of detectors. Each detector consists of 400 small individual yttrium aluminum perovskite (YAP) scintillator crystals of dimensions 2 x 2 x 15 mm3, optically isolated and glued together, which are coupled to position-sensitive photomultiplier tubes (PSPMT's). The detector modules can be moved in a radial direction so that the detector-to-detector spacing can be varied. Special hardware has been built for coincidence detection, position detection, and real-time data acquisition, which is performed by a PC. The single-event data are transferred to workstations where the radioactivity distribution is reconstructed. The dimensions of the crystals and the detector layout are the result of extensive simulations which are described in this report, taking into account sensitivity, spatial resolution and additional parameters like parallax error or scatter effects. For the three-dimensional (3-D) reconstruction a genuine 3-D expectation-maximization (EM)-algorithm which can include the characteristics of the detector system has been implemented. The reconstruction software is flexible and matches the different detector configurations. The main advantage of the proposed animal PET scanner is its high flexibility, allowing the realization of various detector-system configurations. By changing the detector-to-detector spacing, the system is capable of either providing good spatial resolution or high sensitivity for dynamic studies of pharmacokinetics.

Algorithms↗
PubMed1997

Evidence for a multimeric subtilin synthetase complex.

Subtilin is a lanthionine-containing peptide antibiotic (lantibiotic) produced by Bacillus subtilis. It is ribosomally synthesized as a prepeptide and modified posttranslationally. Three proteins of the subtilin gene cluster (SpaB, SpaC, and SpaT) which are probably involved in prepeptide modification and transport have been identified genetically (C. Klein, C. Kaletta, N. Schnell, and K.-D. Entian, Appl. Environ. Microbiol. 58: 132-142, 1992). Immunoblot analysis revealed that production of SpaC is strongly regulated (Z. Gutowski-Eckel, C. Klein, K. Siegers, K. Bohm, M. Hammelmann, and K.-D. Entian, Appl. Environ. Microbiol. 60:1-11, 1994). Transcription of the SpaC protein started in the late logarithmic growth phase, reaching a maximum in the early stationary growth phase. No SpaC was detectable in the early logarithmic growth phase. Deletions within the spaR and spaK genes, which act as a two-component regulatory system, resulted in failure to express SpaB and SpaC, indicating that these two genes are the regulatory targets. Western blot analysis of vesicle preparations of B. subtilis revealed that the SpaB, SpaT, and SpaC proteins are membrane bound, although some of the protein was also detectable in cell extracts. By using the yeast two-hybrid analysis system for protein interactions, we showed that a complex of at least two each of SpaT, SpaB, and SpaC is most probably associated with the substrate SpaS. These results were also confirmed by coimmunoprecipitation experiments. In these cosedimentation experiments, SpaB and SpaC were coprecipitated by antisera against SpaC, SpaB, and SpaT, as well as by a monoclonal antibody against epitope-tagged SpaS, indicating that these four proteins are associated.

Anti-Bacterial Agents↗
PubMed1997

Elevated anticardiolipin antibodies in autoimmune haemolytic anaemia irrespective of underlying systemic lupus erythematosus.

In patients with systemic lupus erythematosus (SLE) and concomitant Coombs positive autoimmune haemolytic anaemia (AIHA) anticardiolipin antibodies (aCL) are found more frequently and at higher titres than in SLE patients without AIHA. In order to assess if aCL elevation is primarily associated with the underlying SLE, or with AIHA itself, we examined AIHA patients with and without underlying SLE for the presence of aCL. aCL (IgG and IgM) were determined by ELISA in 74 SLE patients without AIHA, 22 SLE patients with AIHA, 50 patients with idiopathic AIHA (warm-reactive autoantibodies), 52 patients with idiopathic AIHA (cold-reactive autoantibodies) and 50 healthy controls. The mean IgG and IgM aCL titres in SLE patients without AIHA (IgG 37.0 U/ml, IgM 8.9 U/ml) were significantly elevated compared with the values in healthy controls (IgG 9.1 U/ml, IgM 3.2 U/ml; P < 0.005). The mean aCL levels in SLE patients with AIHA (IgG 53.2 U/ml, IgM 28.2 U/ml) were higher than in SLE patients without AIHA (P = 0.09 for IgG, P < 0.005 for IgM). Interestingly, the mean aCL levels of patients with idiopathic AIHA (warm-reactive autoantibody type: IgG 29.2 U/ml, IgM 19.3 U/ml; cold-reactive autoantibody type: IgG 27.4 U/ml, IgM 18.9 U/ml) were also significantly elevated compared with healthy controls P < 0.001). As aCL are elevated not only in SLE (with and without concomitant AIHA) but also in idiopathic AIHA it can be speculated that aCL are involved in the pathomechanism of autoantibody-induced erythrocyte destruction per se irrespective of an underlying SLE.

Anemia, Hemolytic, Autoimmune↗
PubMed1997

Postoperative color flow duplex scanning in aortic endografting.

PURPOSE: To report the feasibility and sensitivity of duplex sonography compared to computed tomography (CT) for aortic endograft follow-up surveillance. METHODS: In a 26-month period, 113 aortic aneurysm patients received 79 tube and 34 bifurcated stent-grafts. Follow-up used contrast-enhanced CT scanning and duplex sonography with an intravenous ultrasound contrast agent (Levovist). RESULTS: Eleven patients (9.7%) were converted to open repair; 1 died from hemorrhagic shock secondary to retroperitoneal hematoma. The mean follow-up time was 7.2 months (range 1 to 24), during which 5 patients died of unrelated causes. Sixteen primary (within 30 days) and 5 secondary endoleaks were detected by duplex after tube graft implantation. Among 5 endoleaks due to retrograde side-branch perfusion, 3 were detected only with contrast-enhanced duplex scanning. Iliac artery occlusion was also documented using duplex; however, 2 stent fractures could not be seen with ultrasound. Ten primary endoleaks were detected in bifurcated stent-graft patients. One endoleak originating from the distal iliac limb anchoring site was missed by duplex owing to bowel gas. Graft limb thrombosis was clearly identified by lack of a flow signal on duplex. CONCLUSIONS: Duplex sonography could be a valuable, reliable, and economical surveillance tool for endovascular aortic reconstructions. The adjunctive use of an intravenous ultrasound contrast agent increased the sensitivity for detecting endoleak to a level comparable to contrast-enhanced CT scanning. However, stent fractures may not be seen on ultrasound, and bowel gas can interfere with obtaining an adequate image.

Adult↗
PubMed1997

[Myocardial infarction caused by exertion].

Myocardial infarction is the main cause of sudden death during physical exercise, particularly in subjects over 40 and may even occur in high-performance young athletes. Sports and physical activity have a beneficial effect in preventing cardiovascular diseases, but certain rules of prudence must be followed to avoid the risk of a severe coronary event. Myocardial infarction always occurs in particularly susceptible subjects with several risk factors, predominantly smoking, hypercholesterolemia, family history of atherosclerosis. Dietary factors, either before, during or after the exercise, are always found. Distribution of coronary lesions differs with age. Before 40 years, the coronary network is normal in 40% of the cases. The infarction is partially explained by platelet hyperaggregahility and coronary spasms at exercise or in the post-exercise period.

Age Factors↗
PubMed1997

[Calcium antagonists and development of the atheromatous plaque].

Transmembrane movements of calcium are implicated at different stages od the process of formation of the human atheromatous plaque. Calcium antagonist drugs have been shown, in several experimental models and in preliminary clinical trials, to slow the progression of atheromatous lesions. These pharmacodynamic effects could represent one of the mechanisms of the eventual long-term benefits of this pharmacological class. There are many techniques of assessing the atheromatous plaque in vivo but none of them represent a "criterion of substitution" establishing the confirmation of a therapeutic effect of a calcium antagonist drug or any other pharmacological class of drugs. The techniques applicable on a large scale are mainly ultrasonic evaluation of the non-coronary carotid and femoral arteries, providing information on the dimensions of the plaque rather than on its structure. The risk of progression of atheromatous plaques depends more on its structure, its histological and chemical composition, than on its dimensions, at least with regards to coronary lesions. In addition, the influence of treatment of atheromatous plaques of large arteries is not always representative of its effect on coronary lesions which are smaller and are submitted to very different conditions of perfusion. Only long-term studies of morbidity and mortality on large populations may demonstrate a beneficial effect on the progression of coronary artery disease itself. Techniques of evaluation of the atheromatous plaques have a role to play in ancilliary trials, satellites of these large scale studies of morbidity and mortality, but cannot be accepted as criteria of substitution.

Arteriosclerosis↗
PubMed1997

Pharmacological and therapeutic basis for combined administration of beta blockers and calcium channel blockers in the treatment of stable chronic angina.

Pharmacodynamics of beta-adrenergic blockers and dihydropyridines are potentially synergic in the treatment of angina pectoris. The anti-ischaemic effect of beta blockers is mainly the consequence of reductions in heart rate and inotropism, while DHPs promote afterload reduction and coronary vasodilation. Furthermore, beta blockers antagonise the possible dihydropyridines-induced reflex sympathetic activation. Despite these mechanistic considerations the results of clinical trials are not homogeneous. Differences in the assessment of the beta blocker-dihydropyridines connection are due to differences in trial design, dosage and formulation of both dihydropyridines and beta-blockers, and in baseline characteristics of the study population. The predominant finding is that a combination of a dihydropyridines and a beta blocker is not superior to either drug alone as a first step treatment of unselected patients with stable or unstable angina. In contrast, combination therapy is often efficacious when residual ischaemia is present under dihydropyridines or beta blocker monotherapy. That this combination is usually well tolerated thus appears to represent a useful treatment of severe angina pectoris. Combination of a non-dihydropyridines calcium antagonist such as diltiazem or verapamil with a beta blocker offers similar synergistic anti-ischaemic effects, but the addition of their negative chronotropic action may lead to severe bradycardia and thus limit its usefulness, especially in elderly patients with conduction disturbances.

Adrenergic beta-Antagonists↗
PubMed1996

Molecular Mobility in Liquid and in Frozen Micellar Solutions: EPR Spectroscopy of Nitroxide Free Radicals

EPR spectra of stable nitroxide radicals in fluid and in frozen micellar solutions of cationic and anionic surfactants were recorded. Analysis of the obtained spectra gave information on the mobility of molecules in the electrical double layer, in the core of the micelle and in the bulk water phase. In fluid solution the viscosity near the surface of the micelle is higher than in the water phase. It increases with increasing chain length of the surfactant and with increasing atomic number of the counterion. The viscosity in the inner cores of the micelles exceeds that of the water phase by factors up to 30 and that near the surface by factors between 10 and 20. The mobility within the micelle decreases with increasing atomic number of the counterion. In frozen micellar solutions there is no significant mobility in the core of the micelle up to the macroscopic melting point. In the double layer, however, mobility is detected at temperatures >240 K. This can be explained by local melting point depression because of the high local ion concentration in the double layer.

Journal Article↗
PubMed1996

Left radial approach for coronary angiography: results of a prospective study.

Although radial approach has been shown to be feasible for coronary angiography, angioplasty, and even stent placement, there have been no prospective evaluations of ease and safety of left radial approach for coronary angiogram. We examined procedural duration and success as well as complications in 415 consecutive patients. Radial artery occlusion was assessed immediately post-procedure and at 2 month follow-up using echo-Doppler measurements. Procedure failure rate was 9%, mean time for sheath insertion was 4.7 +/- 4.7 min, and mean procedure duration was 19.1 +/- 8.2 min. No major complications occurred. Asymptomatic radial artery occlusion was noted in 71% of the first 49 patients, decreased to 24% in the next 119 receiving 2,000-3,000 units of heparin, and to 4.3% in the last 210 receiving 5000 (p < 0.05). Comparison with the femoral approach in the same laboratory suggested that the radial approach took longer, but provided similarly high-quality results without great difficulty in coronary cannulation. Hence, the left radial approach for coronary angiography (with heparin administration) allows immediate ambulation and may be especially useful for outpatients and when the femoral approach is not possible.

Aged↗
PubMed1996

Intracellular membrane proliferation in E. coli induced by foot-and-mouth disease virus 3A gene products.

During picornavirus infection replication of genomic RNA occurs in membrane-associated ribonucleoprotein complexes. These replication complexes contain different nonstructural viral proteins with mostly unknown function. To examine the function of nonstructural picornaviral proteins in more detail, cDNA of foot-and-mouth-disease virus (FMDV) strain O1 Lausanne was cloned into lambda ZAP II, and different parts of the P3-coding sequence were expressed in E. coli by the T7 polymerase system. Expression products constituted (a) fusion proteins composed of N-terminal leader peptide of bacteriophage T7 phi 10 protein fused to FMDV P3-sequences of different lengths, (b) translation products of authentic P3-region genes, and (c) carboxy-terminally truncated 3A proteins. Expression products were characterized by NaDodSO4-polyacrylamide gel electrophoresis, immunoblotting, as well as electron and immunoelectron microscopy. We show here that in the T7 polymerase system a high level of expression of 3A-containing peptides is achieved in E. coli. Remarkably, the expression of 3A-derived proteins induced a dramatic intracellular membrane proliferation in E. coli cells, similar to the vesicle induction observed in FMDV-infected cells. By immunoelectron microscopy, 3A-reactive material was found associated with these membranes. We hypothesize that the FMDV 3A protein is instrumental in eliciting intracellular membrane proliferation in infected cells as a prerequisite for viral RNA replication.

Aphthovirus↗
PubMed1996

Management of retrohepatic venous injuries with atrial caval shunts.

Retrohepatic inferior vena caval injuries resulting from blunt or penetrating abdominal trauma are rare but devastating events that remain formidable challenges to even the most experienced Level I trauma center team members. Prepackaged atrial caval shunts have improved emergency medical treatments, and prior planning and coordination by perioperative nurses allow for rapid response by surgical team members. These efforts provide an optimal level of care required to increase patient survival. This article provides a general overview of abdominal trauma and retrohepatic inferior vena caval injuries and a proactive plan to meet the needs of patients with these injuries.

Abdominal Injuries↗
PubMed1996

Parenteral glycyl-L-tyrosine maintains tyrosine pools and supports growth and nitrogen balance in phenylalanine-deficient rats.

Poor solubility hampers the addition of sufficient amounts of free tyrosine to parenteral amino solutions. We investigated the use of a highly soluble synthetic dipeptide, glycyl-L-tyrosine, as a parenteral tyrosine source in 18 male Wistar rats (body weight 180-200 g). The animals were randomized into three equal groups and catheterized to facilitate isoenergetic (1.2 MJ.kg-1.d-1) and isonitrogenous (1.25 g nitrogen.kg-1.d-1) total parenteral nutrition for 7 d. Controls (Group 1) received a complete amino acid solution, Group 2 received the same solution deficient in phenylalanine (nitrogen replaced with glycine), and group 3 received the phenylalanine-deficient solution supplemented with glycyl-L-tyrosine. Between d 4 and 7, weight gain and nitrogen retention were lower in Group 2 and in Group 1 or 3. In plasma and organ samples obtained at the end of the study, amino acids and dipeptides were analyzed by means of reversed phase-HPLC. In Group 2, phenylalanine and tyrosine concentrations were lower than in controls in plasma, muscle and kidney; in liver, only the tyrosine concentration was lower compared with controls. With glycyl-L-tyrosine supplementation, plasma, liver and kidney tyrosine concentrations and the phenylalanine:tyrosine ratio were normal. Intact glycyl-L-tyrosine was not detectable, suggesting a virtually quantitative elimination or utilization of the infused dipeptide. The results indicate that in phenylalanine-deficient rats, parenteral glycyl-L-tyrosine rapidly provides free tyrosine to facilitate normal growth, promote nitrogen metabolism and maintain intra- and extracellular tyrosine pools.

Amino Acids↗