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Biomedical subjects

S Koch

Publications and source records attributed to S Koch.

At least 73 records · Page 4Linked to original sources

Etiologic factors of acute aortic dissection in children and young adults.

Current concepts in the pathophysiology and predisposing conditions of acute aortic dissection in children, adolescents, and young adults are presented. Timely diagnosis is required for this life-threatening condition. Most children and adolescents with aortic dissection have congenital cardiovascular anomalies. Certain heritable disorders involving connective tissue also predispose to this disorder. Newer associations include cocaine abuse and weight lifting. To facilitate early diagnosis, the salient physical findings of the known predisposing conditions are reviewed. Clinical presentation and diagnostic imaging of aortic dissection are briefly summarized. Physicians working in an acute care setting, particularly in the emergency room, should be aware of disorders predisposing to acute aortic dissection in the pediatric and young adult population. Practitioners conducting school or college preparticipation sports evaluations can make use of such information in their assessment of risk for sudden death.

Acute Disease↗

Comparative neuroprotective efficacy of prolonged moderate intraischemic and postischemic hypothermia in focal cerebral ischemia.

OBJECT: The purpose of this study was to compare the effects of prolonged hypothermia on ischemic injury in a highly reproducible model of middle cerebral artery (MCA) occlusion in rats. METHODS: Male Sprague-Dawley rats were anesthetized with halothane and subjected to 120 minutes of temporary MCA occlusion by retrograde insertion of an intraluminal nylon suture coated with poly-L-lysine through the external carotid artery into the internal carotid artery and the MCA. Two levels of prolonged postischemic cranial hypothermia (32 degrees C and 27 degrees C) and one level of intraischemic cranial hypothermia (32 degrees C) were compared with the ischemic normothermia (37 degrees C) condition. Target cranial temperatures were maintained for 3 hours and then gradually restored to 35 degrees C over an additional 2-hour period. The animals were evaluated using a quantitative neurobehavioral battery of tests before inducing MCA occlusion, during occlusion (at 60 minutes postonset in all rats except those in the intraischemic hypothermia group), and at 24, 48, and 72 hours after reperfusion. The rat brains were perfusion fixed at 72 hours after ischemia, and infarct volumes and brain edema were determined. Both intraischemic and postischemic cooling to 32 degrees C led to similar significant reductions in cortical infarct volume (by 89% and 88%, respectively) and total infarct volume (by 54% and 69%, respectively), whereas postischemic cooling to 27 degrees C produced lesser reductions (64% and 49%, respectively), which were not statistically significant. All three hypothermic regimens significantly lessened hemispheric swelling and improved the neurological score at 24 hours. The authors' data confirm that a high degree of histological neuroprotection is conferred by postischemic cooling to 32 degrees C, which is virtually equivalent to that observed with intraischemic cooling to the same level. CONCLUSIONS: These results may be relevant to the design of future clinical trials of therapeutic hypothermia for acute ischemic stroke.

Animals↗

[Trends for the management of pancreatic adenocarcinoma in a hospitalized-based population (1980-1994)].

OBJECTIVE: To determine the trends for the management of pancreatic adenocarcinoma between 1980 and 1994 in a hospital-based population. METHODS: Data of patients from the Doubs department and hospitalized for pancreatic adenocarcinoma in the University Hospital of Besançon were analyzed. Two study periods were determined: 1980-1989 and 1990-1994. RESULTS: One hundred and thirty five cases were diagnosed (77 male, 58 female, mean age 65.6 +/- 12.1 years). Weight loss (62.3%), pain (52.7%) and jaundice (43.3%) were the most frequently reported symptoms. Their proportion and their duration were similar according to the period. Diagnosis of the pancreatic tumor was made by ultrasonography or tomodensitometry in 97.8% patients. Distribution of tumors according to the AJCC staging was unchanged during the study. Pre-operative screening frequently underestimated tumor stage, even in the more recent period. The rate of complete resection (18.5%) did not increase. The 5-year actuarial survival rate (3.05%) remained unchanged. A metastatic spread represented the only independent prognostic factor. CONCLUSIONS: The management and the prognosis of pancreatic adenocarcinoma have not fundamentally changed. Recent imaging techniques should improve staging accuracy. Advances in adjuvant therapies represent a major issue for the future.

Adenocarcinoma↗

Effective and quality-controlled use of digital radiography in dental practice.

During the last years, the number of commercially available digital radiographic systems has increased rapidly. Nevertheless, they are hardly used in practice because several drawbacks still hinder dental practitioners from using digital radiography effectively in their routine work. In order to allow effective use of such systems in the dental practice, they must be integrated into the daily routine in an ergonomically optimal way and be driven by software following the rules of cognitive ergonomy and perception. The most important prerequisite for meaningful use of digital radiography in the dental practice is that it supports instead of disturbs daily clinical work. The underlying software should be easily comprehensible and intuitively applicable. This paper discusses advantages and disadvantages of digital compared to conventional radiography and how the introduction of digital radiography in dental practice affects clinical work. A concept is introduced that enables effective and quality-controlled use of digital radiographic systems in the dental practice by taking cognitive ergonomic aspects of the clinical work situation into account. This concept comprises the design of image databases for efficient storage and retrieval, the quality-controlled use of image manipulation methods adapted to the clinical requirements during diagnostic interpretation, and the usage of decision support systems for diagnosis and therapy of radiographic lesions.

Databases as Topic↗

Mutation induction by different types of radiation at the Hprt locus.

Mutation induction at the Hprt locus in Chinese hamster cells was studied after exposure to ultraviolet light, X-rays and alpha particles. While mutant frequency as a function of dose or fluence followed a linear-quadratic relationship with UV and X-rays, it showed a linear dependence for alpha particles. If mutant frequency is plotted vs. the logarithm of surviving fraction, a linear relationship is found in all cases although with different slopes. These are about equal with the two types of ionising radiations but about 10 times larger for UV. They can be used as a measure of mutagenic potential and are termed mutagenicity. It is shown that this parameter is correlated with the maximum of mutant yield, i.e., the number of mutants per cell at risk. It is concluded from this analysis that the maximum mutant yield is always found at doses or fluences which lead to 37% survival irrespective of the kind of radiation. If mutation induction is measured in X-irradiated cells after pre-exposure to UV, mutant frequency is higher than expected on the basis of independent action of the two radiations. Deletion spectra were determined by using multiplex polymerase chain reaction. It was found that the background of spontaneous mutants varied considerably and showed frequently repetitive patterns, presumably because of clonal expansion of pre-formed mutants. UV-induced mutants did not contain any deletions, while those with both X-rays and alpha particles the majority displayed partial and total deletions. Based on a total number of 134 X-ray- and 192 alpha-induced mutants, it is concluded that the total fraction of mutant clones without deletions (partial or total) is about 40% for X-rays and only about 20% for alpha-particles.

Alpha Particles↗

Protein detection with a novel ISFET-based zeta potential analyzer.

This publication presents a novel ISFET-based measurement concept for the determination of the zeta potential, which is known to be an efficient method for the detection of protein accumulations onto surfaces. The basic set-up consists of two monolithically integrated ISFET sensors arranged in a serial flow configuration together with a precoated fused silica capillary, which provides the reactive surface for the protein detection. In comparison with the state of the art, this novel biosensor system is characterized by a small size, an extremely low reagent consumption, a simple fluidic concept, a short analysis time, and a very effective noise suppression due to the differential ISFET set-up. In the following, an overview is given over the theoretical background of the measurement principle. In order to get deeper insight into the theoretical background of the measurement principle, a simulation model was developed which is based on the site-binding theory and takes into account the different proton dissociation equilibria of the surface groups as well as the influence of monovalent electrolyte ions. A quasi-Newton iteration after Broyden was used for the numerical solution of the formulated equation system. For an experimental confirmation of the simulation results, the calculated zeta potential vs. pH curves were compared with measured data for various modifications of the fused silica capillaries (in untreated state, after a hydrothermal activation, and after the deposition of several silanes) and it could be shown, that the chosen physical model represents a satifactory theoretical basis for the description of the occuring surface effects. Measurements before and after a covalent coupling of the model analyte lysozyme were performed in order to demonstrate the feasibility of an immunosensor based on the measurement of the streaming potential and showed a significant shift of the zeta potential vs. pH curves.

Biosensing Techniques↗

Synovial Epstein-Barr virus infection increases the risk of rheumatoid arthritis in individuals with the shared HLA-DR4 epitope.

OBJECTIVE: To investigate the presence of the Epstein-Barr virus (EBV) in rheumatoid arthritis (RA) synovium and its correlation with the HLA genotype in an attempt to elucidate the role of EBV in the pathogenesis of RA. METHODS: EBV DNA/RNA was investigated by polymerase chain reaction (PCR) analysis of synovial tissue from 84 patients with RA and from 81 patients with non-RA arthritis (controls) and was correlated with the patients' HLA genotype. RESULTS: EBV DNA and EBV-encoded RNA 1 transcripts were significantly more frequently present in synovial tissue from the RA patients (29 of 84) than in that from the non-RA patient controls (8 of 81). EBV DNA-positive individuals had a 5.47 times higher risk of presenting with RA than did EBV DNA-negative individuals. In HLA-DRB1*0401,0404,0405,0408-positive or shared epitope-positive patients, the risk was further increased (odds ratio for EBV and HLA-DR4 approximately 41, for EBV and the shared epitope approximately 15) compared with those who lacked both EBV DNA and RA-linked HLA genotypes. CONCLUSION: EBV seems to function as an environmental risk factor for RA, particularly in patients with the RA-linked HLA-DRB1 alleles.

Adult↗

Primary disease recurrence after liver transplantation for alveolar echinococcosis: long-term evaluation in 15 patients.

Between 1986 and 1991, 21 patients received liver grafts in our center for incurable alveolar echinococcosis (AE). The aim of this study was to analyze the long-term results in 15 of these 21 patients who survived more than 1 year after undergoing a liver transplantation (LT). The follow-up, mainly aimed at the diagnosis of recurrence, consisted of repeated radiological and specific immunological investigations. The role of pre- and post-LT benzimidazole (BZM) therapy was also evaluated. Among the 15 patients, 8 patients had a palliative LT related to previously known pulmonary AE metastases and/or inextirpable abdominal parasitic foci. In the 7 remaining patients, LT was considered curative. In June 1998, the mean follow-up duration was 96 months (range: 28-138 months). Five late deaths occurred, 2 of them were directly related to residual AE. A reinfection of the graft was observed in 4 patients. Preoperative BZM therapy seemed useful in preventing or delaying the parasitic recurrence. Post-LT BZM was able to stabilize and even to reduce residual AE. The anti-Em2 enzyme-linked immunosorbent assay (ELISA), which is the standard test used in patient follow-up after partial liver resection for AE, did not appear useful in detecting recurrence here; however, an ELISA, using a crude heterologous antigen (Echinococcus granulosus) allowed early diagnosis of residual AE. In conclusion, primary disease recurrence is not rare after LT for AE. Immunosuppressive therapy may favor larval growth in extrahepatic sites; therefore, an extensive extrahepatic radiological check-up has to be performed before LT. BZM therapy seems to stabilize residual foci. Anti-Eg immunoglobulin G (IgG) follow-up is the most useful test for early diagnosis of parasite recurrence.

Adult↗

Protective effects of Ginkgo biloba extract EGb 761 on the myocardium of experimentally diabetic rats. II. Ultrastructural and immunohistochemical investigation on microvessels and interstitium.

Interstitial and microvascular disorders are known as a characteristic part of the diabetic cardiomyopathy and to resist partly insulin therapy. Aim of this study was to demonstrate structure-protecting effects of Ginkgo Extract EGb 761 known as a natural radical scavenger in streptozotocin-diabetic rats on the microvascular compartment. Wistar rats (n = 5) were made diabetical by i.p. injection of 60 mg/kg body mass streptozotocin for 4 months. Rats of the protected group (n = 5) received daily 100 mg/kg body mass EGb 761 for 3 months, starting 1 month after induction of diabetes. 5 age-matched rats served as control. The volume fraction of interstitium was slightly but significantly increased only in the unprotected diabetic group. Diminishing of the capillary to the myocyte ratio was seen in the diabetic but not in the protected group. Immunostaining of collagen revealed a slight increase of type III, type IV, and type VI fibres in the interstitium, more expressed in the unprotected group. Ultrastuctural morphometry revealed significant thickening of endothelial and muscular basement membranes in diabetic animals, less expressed in the EGb- protected group. The capillary diameter was slightly increased in the diabetic and slightly decreased in the protected group. The number of plasmalemmal vesicles was tendentially more decreased, that of lysosomes more increased in the diabetic than in the protected group. It is concluded that EGb 761 can diminish partly interstitial fibrosis and reduce endothelial and muscular basement membrane thickening of the diabetic myocardium. It may contribute to prevent late diabetic complications.

Animals↗

Corneodesmosin gene polymorphism demonstrates strong linkage disequilibrium with HLA and association with psoriasis vulgaris.

Corneodesmosin (CD) is thought to play a key role in corneocyte cohesion, and its proteolysis appears to be a major event in the process of desquamation. Recently it was shown that CD is encoded by the S-gene, which is located approximately 160 kb telomeric of HLA-C. In the present study, the role of CD in the genetics of psoriasis vulgaris was studied in greater detail. The second exon of the CD gene was sequenced in 86 HLA-typed individuals from 13 psoriasis multiplex families. A total of 11 silent dimorphisms and 7 variants resulting in amino acid substitutions were found. Pedigree analysis showed that these variants could be grouped into 7 alleles, encoding 6 different amino acid sequences. These alleles are in strong linkage disequilibrium with HLA-B and -C, indicating that the polymorphism of the CD gene is ancient and well conserved rather than sporadic. One allele at the CD locus, designated CD2, displayed strong linkage disequilibrium with HLA-Cw6, the HLA allele most prominently associated with psoriasis. CD2 demonstrated a greater relative risk than Cw6 (3.4 vs. 2.5, not significant) and higher significant transmission disequilibrium with psoriasis than any of the investigated HLA-alleles. Due to its biologic function, cellular location and disease association, the CD gene appears to be an excellent candidate gene for PSORS1, the HLA-linked determinant of psoriasis vulgaris.

Alleles↗

Molecular elements of ion permeation and selectivity within calcium channels.

Voltage-dependent calcium channels are located in the plasma membrane and form a highly selective conduit by which Ca2+ ions enter all excitable cells and some nonexcitable cells. Extensive characterization studies have revealed the existence of one low (T) and five high-voltage-activated calcium channel types (L, N, P, Q, and R). The high voltage-activated calcium channels have been found to exist as heteromultimers, consisting of an alpha1, beta, alpha2/delta, and gamma subunit. Molecular cloning has revealed the existence of 10 channel transcripts, and expression of these cloned calcium channel genes has shown that basic voltage-activated calcium channel function is strictly carried by the corresponding alpha1 subunits. In turn, the auxiliary subunits serve to modulate calcium channel function by altering the voltage dependence of channel gating, kinetics, and current amplitude, thereby creating a likelihood for calcium channels with multiple properties. Although for calcium channels to be effective, Ca2+ ions must enter selectively through the pore of the alpha1-subunit, bypassing competition with other extracellular ions. The structural determinants of this highly selective Ca2+ filter reside within the four glutamic acid residues located at homologous positions within each of the four pore-forming segments. Together, these residues form a single or multiple Ca2+ affinity site(s) that entrap calcium ions, which are then electrostatically repulsed through the intracellular opening of the pore. This mechanism of high-selectivity calcium filtration, the spatial arrangement of pore glutamic acid residues, and the coordination chemistry of calcium binding are discussed in this review.

Calcium↗

Combined antithrombin III and C1-esterase inhibitor treatment decreases intravascular fibrin deposition and attenuates cardiorespiratory impairment in rabbits exposed to Escherichia coli endotoxin.

OBJECTIVE: To assess the effect of a combined antithrombin III and C1-esterase inhibitor treatment on intravascular organ fibrin deposition and cardiorespiratory changes following intravenous Escherichia coli endotoxin (lipopolysaccharide [LPS] 80 microg/kg i.v.) exposure. DESIGN: Prospective, randomized trial. SETTING: Research laboratory of a university medical center. SUBJECTS: Anesthetized, instrumented and mechanically ventilated rabbits ([Chbb:CH); n = 40). INTERVENTIONS: Endotoxin was given to 30 animals. Ten animals received no inhibitor (endotoxin control group). The other animals were either treated by high-dose (300 units/kg; n = 10) or low-dose (100 units/kg; n = 10) combined antithrombin III and C1-esterase inhibitor administration. Ten rabbits (time control group) were given placebo (sodium chloride 0.9%). Cardiorespiratory variables were assessed at baseline, 120 mins, and 240 mins after endotoxin or placebo administration. Four hours after endotoxin injection, liver, lung, and kidney tissue samples were examined for intravascular fibrin deposition by light microscopy. MEASUREMENTS AND MAIN RESULTS: Inhibitor treatment significantly decreased clot formation in lungs and livers without, however, demonstrating a clear dose-dependent effect. Combined antithrombin III/C1-esterase treatment attenuated the decrease of mean arterial pressure and cardiac output observed following endotoxin injection. Blood pressure improvement was significantly dependent on dosage administered. CONCLUSION: Combination of antithrombin III and C1-esterase inhibitor treatment during early endotoxin shock decreased organ fibrin deposition and improved cardiovascular stability.

Animals↗

Long-term neuropsychological consequences of maternal epilepsy and anticonvulsant treatment during pregnancy for school-age children and adolescents.

PURPOSE: Antiepileptic drugs (AEDs) are potential teratogenic agents. The purpose of this study was to examine the long-term effects of intrauterine AED exposure on neurologic and psychological functioning. METHODS: Of a prospective study, "Epilepsy, pregnancy, and child development," children could be retraced at school age and adolescence. Sixty-seven were born to mothers with epilepsy [no drugs during pregnancy (n = 13), monotherapy (n = 31), polytherapy (n = 23)]; 49 were nonafflicted control children. Assessments included an intelligence test (Wechsler), a neurologic examination (Touwen), and an EEG. Data analyses were performed, controlling for parental social status, type of maternal drug therapy and drug dosage, type of epilepsy, frequency of seizures during pregnancy, the original subgroups, and specific drug effects. RESULTS: Type of maternal epilepsy and type and kind of AED therapy, but not maternal seizures during pregnancy correlated with an increase in abnormal EEG patterns. Minor neurologic dysfunction was diagnosed, with increased frequency from the control to the risk/no drug or monotherapy to the polytherapy group. The compromised intelligence score of the polytherapy group was primarily due to those children who had been exposed to primidone (PRM). Level of IQ was negatively associated with PRM dosage. CONCLUSIONS: Maternal epilepsy and AED therapy during pregnancy appear to have long-term effects on the offspring well into adolescence, as evinced in EEG patterns, minor neurologic dysfunction, and intellectual performance. Severity of effects increased from control group to epilepsy/no-drug group to monotherapy group and was most marked in the polytherapy group. These group differences are assumed to reflect differential neural vulnerability to social and family factors.

Adolescent↗

Diagnosis and prognosis of neuroendocrine tumours of the lung by means of high resolution image analysis.

Neuroendocrine tumours (NET) of the lung are divided in subtypes with different malignant potential. The first is the benign or low-grade malignant tumours, well-differentiated, called typical carcinoids (TC) and the second is the high-grade malignant tumours, poorly differentiated of small (SCLC) or large cell type (LCLC). Between these tumour types lies the well-differentiated carcinoma with a lower grade of malignancy (WDNEC). In clinical routine it is very important with regard to prognosis to distinguish patients with low malignant potential from those with higher ones. In this study 32 cases of SCLC, 13 of WDNEC and 14 of TC with a follow-up time up to 7 years were collected. Sections 4 microm thick from paraffin embedded tissue were Feulgen stained. By means of high resolution image analysis 100 nuclei per case were randomly gathered to extract morphometric, densitometric and textural quantitative features. To investigate the ploidy status of the tumour the corrected DNA distribution was calculated. Stepwise linear discriminant analysis to differentiate the classes and Cox regression analysis for the survival time analysis were applied. Using chromatin textural and morphometric features in two two-class discriminations, 11 of the 14 TC cases and 8 of the 13 WDNEC cases were correctly classified and 11/13 WDNEC cases and 28/32 SCLC cases, respectively. The WDNEC cases are more similar in chromatin structure to TC than to SCLC. For the survival analysis, only chromatin features were selected to differentiate patients with better and worse prognosis independent of staging and tumour type.

Adolescent↗