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Biomedical subjects

H Köhler

Publications and source records attributed to H Köhler.

At least 91 records · Page 5Linked to original sources
PubMed1998

Analysis of lysergic acid diethylamide: comparison of capillary electrophoresis with laser-induced fluorescence (CE-LIF) with conventional techniques.

The increasing use of the potent hallucinogenic drug D-lysergic acid diethylamide (LSD) makes the application of highly sensitive analytical techniques necessary. For an effective analysis of biological specimens a limit of detection in the sub-ng/ml range is required. Using capillary electrophoresis (CE), with laser-induced fluorescence detection it was possible to determine 0.1-0.2 ng LSD/ml blood. The conventionally used immunoassays and gas and high-performance liquid chromatographic methods have cut-off values and limit of detection, respectively, in the same range. Only tandem mass spectrometry techniques can be more sensitive. Therefore, CE can be considered a good complementary method to conventional immunological and chromatographic techniques for the forensic analysis of biofluids.

Blood Chemical Analysis↗
PubMed1998

[Evaluation of the function of the tubular esophagus in patients with progressive systemic scleroderma based on a standardized symptom score].

BACKGROUND AND OBJECTIVE: The oesophagus is the internal organ most often affected in progressive systemic scleroderma (PSS). Suitable methods for demonstrating oesophageal involvement are available in only a few centres. Aim of this study was to validate a standardized symptom score for assessing oesophageal function in patients with PSS. PATIENTS AND METHODS: Oesophageal symptoms of dysphagia, odynophagia (pain on swallowing), heartburn and regurgitation were assessed in 27 consecutive patients with PSS. Intensity (0 to 3 points) and frequency (1 to 4 points) of these symptoms were quantified using a standardized system (after de Dombal and Hall): points per symptom (0 to 12) and points per patient (0 to 48). Results were compared with long-term manometric recordings as reference. The control group consisted of 20 healthy volunteers matched for age and sex. RESULTS: Healthy controls and patients with PSS had significantly different oesophageal motility: 22 of 27 patients fulfilled the criteria of oesophageal hypomotility. Using a total symptoms score of 8 points (points per patient) as limit of normal, the sensitivity of the scoring for the diagnosis of abnormal oesophageal function was 68%, with a specificity of 100%, positive predictive value of 100% and a negative predictive value of 42%. INTERPRETATION: The reported method of symptom scoring provides a valid means of positive prediction of (abnormal) oesophageal function, making manometric investigation unnecessary. Absence or an only mild degree of oesophageal symptoms does not exclude abnormal motility so that manometry must be performed in such patients.

Deglutition Disorders↗
PubMed1998

Stimulation of HIV-1-neutralizing antibodies in simian HIV-IIIB-infected macaques.

Previously we have discovered a public idiotope, designated 1F7, that is expressed on antibodies against HIV type 1 (HIV-1) in human and nonhuman primates. To test the potential of mouse monoclonal antibody (mAb) 1F7 as a therapeutic anti-clonotypic antibody in HIV-1-infected patients, we used the simian HIV-IIIB macaque infection model, which mimics several immunological and pathological characteristics of HIV-1 infection in humans. Four healthy simian HIV-infected rhesus monkeys (Macaca mulatta) expressing the 1F7 marker on anti-gp120 antibodies were selected for this study. Three monkeys of this group were immunized several times with the murine mAb 1F7 i.v., and one monkey received as control an isotype-matched antibody, TEPC183. No serious side effect or allergic reaction was encountered. Blood collected before and during the immunization and over several months afterward were analyzed for neutralizing antibodies. Significant increases in breadth and potency of HIV-1-neutralizing antibody titers to one or more virus strains were detected in all three of the 1F7-immunized monkeys, but not in the control monkey immunized with TEPC183. These results show that an antibody, recognizing a public idiotope associated with anti-HIV-1 antibodies can function in chronically infected primates as an anti-clonotypic immunogen to boost antibodies that neutralize homologous and heterologous virus strains. This study represents a first step toward the preclinical evaluation of 1F7 as a therapeutic AIDS vaccine.

AIDS Vaccines↗
PubMed1998

Differential expression of cell adhesion molecules in inflamed appendix: correlation with clinical stage.

The diagnosis of 'early inflamed', 'recurrent' or 'sub-acute' appendicitis is often difficult and accompanied by controversies between clinical data, histological findings, and their interpretation. The expression of the intercellular cell adhesion molecule-1 (ICAM-1), the vascular cell adhesion molecule-1 (VCAM-1), and E-selectin has been studied in 61 appendicectomy specimens for possible use as a diagnostic tool. This study demonstrates a different expression of CAM by endothelial (EC) and mesothelial cells (MC) in the various stages of appendicitis, with early E-selectin and ICAM-1 expression in EC, followed by VCAM-1 in EC and MC. Appendices from patients with prolonged clinical symptoms defined by clinicians as 'chronic' appendicitis showed VCAM-1 expression and occasionally weak expression of E-selectin in EC. In several cases, discrepancies were found between the pre-operative 'clinical' diagnosis, the histomorphological findings, and the immunohistological results. In this context, the expression of E-selectin and VCAM-1 in comparison with the histological features has potential significance in the diagnosis of 'early acute', 'sub-acute' or 'recurrent' appendicitis. In addition, a correlation was demonstrated between the histological stages of appendicitis and the kinetics of CAM expression. The study also indicates that the time course of E-selectin expression in vivo is longer than is suggested from in vitro data.

Acute Disease↗
PubMed1998

Proof of air embolism after exhumation.

The detection, storage, and analysis of gas taken from the heart ventricle is necessary to diagnose a fatal air embolism and this requires special precautions during autopsy. When the results of gas analysis correspond to the criteria defined by Pierucci and Gherson the diagnosis "air embolism" is justified. In cases showing putrefaction the diagnostic value of gas analysis was negated. In a series of 15 patients who were assumed to have been killed by air injection in a peripheral vein the corpses were exhumed and a full medico-legal examination was carried out including gas analysis. In 8 cases results could be obtained indicating a mixture of embolised air and gases of putrefaction. In two control groups comprising 10 exhumed bodies and 30 cases showing advanced putrefaction, gas analysis showed putrefaction gases except in 5 cases with gas volumes less than 5 ml in the right ventricle. Therefore gas analysis can be helpful to diagnose fatal air embolism even in cases showing putrefaction while the diagnosis of putrefaction gases only does not exclude this diagnosis.

Aged↗
PubMed1998

A specific immunoassay for the determination of morphine and its glucuronides in human blood.

The development of specific antisera for immunochemical determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide is described. Morphine was N-demethylated to normorphine and N-alkylated to give N-aminopropyl-normorphine as hapten for antisera against morphine. As haptens for antisera against morphine-3-glucuronide and morphine-6-glucuronide, N-aminopropyl-nor-morphine was glucuronidated in position 3 or 6 respectively. Each of these three haptens were coupled to BSA employing the glutaraldehyde method to obtain three different immunogens. Immunisation of rabbits with these conjugates gave anti-morphine, anti-morphine-3-glucuronide and anti-morphine-6-glucuronide antisera, which were tested in a competitive, heterogeneous radioimmunoassay. Tracers for this radioimmunoassay procedure were synthesised by substitution of morphine and morphine-6-glucuronide in position 2 with 125I and indirect iodination of the morphine-3-glucuronide hapten according to the method of Bolton and Hunter. The resulting antisera show very specific reactions with morphine, morphine-3-glucuronide and morphine-6-glucuronide. Cross reactivities of each antiserum with structurally related opiates and opioides are very low. The cross reactivities of the anti-morphine antiserum against morphine-3-glucuronide, morphine-6-glucuronide, codeine, codeine-6-glucuronide or dihydrocodeine were less than 0.3%, the anti-morphine-3-glucuronide antiserum against morphine, morphine-6-glucuronide, codeine, codeine-6-glucuronide or dihydrocodeine less than 0.1% and the anti-morphine-6-glucuronide antiserum against morphine, morphine-3-glucuronide, codeine or dihydrocodeine less than 0.1%, against codeine-6-glucuronide less than 2.3%. The determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in blood samples (limit of detection= 3, 1, 0.5 ng/g) of nine cases of fatal heroin overdose with this radioimmunoassay method and the comparison with a GC/MS method is described.

Animals↗
PubMed1998

Chemo-embolization of experimental liver metastases. Part I: distribution of biodegradable microspheres of different sizes in an animal model for the locoregional therapy.

An experimental in vivo rat model was established to simulate the embolization therapy of non-resectable liver metastases with microparticulate systems. The effects of biodegradable microspheres on a transplanted liver-tumor cell line in rat livers were investigated with respect to particle size. The distribution of fluorescence-labelled microspheres was investigated to characterize the effects of long-term embolization with biodegradable microspheres, and the suitability and relevance of this animal model. Novikoff hepatoma cells were implanted into the central liver lobe of Sprague-Dawley rats. After seven days, four batches of fluorescence-marked microspheres (17 microm, 25 microm, 30 microm, and 40 microm) were administered into the proper hepatic artery. Liver(including the tumor), lung and spleen were isolated and frozen sections and tissue cubes of liver-, border-, and tumor tissue were prepared. The sections were examined by fluorescence microscopy. The cubes were extracted and the fluorescence of the marker quantified. During operation, microspheres smaller than 40 microm did not cause complete embolization. The slides showed the spreading of the smaller particles to the spleen and lung. Only 40 microm particles accumulated in the liver and were rarely detectable in other organs. The extraction showed a high concentration of the 40 microm particles in the border tissue. Apparently they were trapped proximal to the tumor capillary system and therefore showed a high ratio of border/tumor concentration. Microparticles smaller than 40 microm had a border/tumor concentration ratio of less than one and were distributed to the spleen and lung. In conclusion, a mean particle diameter of at least 40 microm is required for embolization. Thus, the model shows similarity to clinical situations in the treatment of human liver tumor and metastases.

Animals↗
PubMed1998

Inhibition of oxidant-induced lipid peroxidation in cultured renal tubular epithelial cells (LLC-PK1) by quercetin.

The protective effect of quercetin against oxidant-induced cell injury (hypoxanthine/xanthine oxidase system) was studied in the renal tubular epithelial cell line LLC-PK1. Pretreatment with quercetin provided protection from structural and functional cell damage in a concentration-dependent manner (10-100 microM). Comparison with structural variants revealed that the protective property of quercetin depends on the number of hydroxyl substituents in the B-ring, the presence of an extended C-ring chromophore, 3-D-planarity and lipophilicity, indicating that membrane affinity is essential for protection. The hypothesis that quercetin exerts its protective effects via inhibition of lipid peroxidation was further examined. Protection by quercetin was found when lipid peroxidation, assessed by the release of malondialdehyde, was initiated by H2O2 or by the combination of 1-chloro-2,4-dinitrobenzene and aminotriazole. In contrast, the bioflavonoid was not protective when oxidative cell damage was induced by menadione and occurred in the absence of lipid peroxidation. These data suggest that cytoprotective effects of quercetin are related to membrane affinity and may be explained by interruption of membrane lipid peroxidation rather than by intracellular scavenging of oxygen free radicals.

Animals↗
PubMed1998

Pain and pyuria.

Explore the source record for details and available documents.

Analgesics↗
PubMed1998

Fab-independent antiadhesion effects of secretory immunoglobulin A on S-fimbriated Escherichia coli are mediated by sialyloligosaccharides.

S-fimbriated Escherichia coli strains cause sepsis and meningitis in newborns and are known to recognize the carbohydrate sequence sialyl-(alpha2-3)-galactoside. We show that adhesion of cloned S-fimbriated E. coli to human epithelial cells is inhibited Fab independently by sialyloligosaccharides on secretory immunoglobulin A (s-IgA). This indicates an anti-infective function of s-IgA (Fc), particularly in early human milk.

Adult↗
PubMed1998

Current trends in biocompatibility testing.

Biocompatibility remains the central theme for biomaterials applications in medicine. It is generally accepted that this term means not only absence of a cytotoxic effect but also positive effects in the sense of biofunctionality, i.e. promotion of biological processes which further the intended aim of the application of a biomaterial. The national and international standards for testing regimes represent a lowest common denominator for such applications and do not necessarily ensure that optimal function will be achieved. The authors' thesis is that biocompatibility testing has scope for extensive development with respect to biofunctionality. The present paper reviews current trends in the in vitro aspects of biocompatibility testing. As well as a critical appraisal of the recent literature, future trends are also stressed, which the authors regard as essential for a meaningful integration of a modern biological approach into new developments in the material sciences. These include the application of modern techniques of cell and molecular biology, the concepts of tissue remodelling, hybrid organ development and encapsulated cell technology.

Animals↗
PubMed1998

Production of proinflammatory and regulatory monokines in hemodialysis patients shown at a single-cell level.

Immunologic complications of chronic renal failure are associated with the overproduction of proinflammatory cytokines by monocytes. This is partly due to renal failure itself but is further enhanced by hemodialysis treatment with frequent contact between blood and dialyzer membranes. Previous studies have shown an imbalance of proinflammatory and regulatory monokines in these patients. This study examines monokine production in hemodialysis patients using for the first time a very sensitive method of cytokine detection at a single-cell level by flow cytometry ("cytoflow technique"). Monocytes were stained intracellularly for the production of interleukin-6 (IL-6) and IL-10 after 20 h of culture with lipopolysaccharide. It was shown that high levels of proinflammatory IL-6 in hemodialysis patients are due to an increased number of monocytes producing this cytokine, while IL-6 synthesis per cell remains unchanged. In contrast, elevated levels of regulatory IL-10 are due to an increased synthesis per cell. This study demonstrates that in healthy subjects there is a population of monocytes producing exclusively IL-10 after 20 h of stimulation by lipopolysaccharide. This distinct population of regulatory monocytes is infrequent in dialysis patients, in whom most of the IL-10-positive monocytes also produce IL-6. These findings indicate that overproduction of proinflammatory factors in dialysis patients is at least in part due to a loss of cytokine-specific differentiation in monocytes.

Adult↗
PubMed1997

[Indication and limits to behavioral therapy for patients with chronic pain].

Chronic pain has a variety of causes. Therefore patients with chronic pain should be treated in an interdisciplinary way. From a psychological point of view a cognitive-behavioral approach is preferred. This includes training for coping with pain as well as the added option of a comprehensive psychotherapy. This form of treatment seems to be indicated in most cases, but it is not suitable if the patient does not agree with the procedure, preferring instead a special kind of therapy which is not cognitive-behavioral. On the other hand a psychological treatment is not indicated if the therapist is not prepared to cooperate with other therapists in an interdisciplinary fashion.

English Abstract↗
PubMed1997

[Therapeutic plasma exchange 1996].

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique to remove large molecular weight substances. Since the late seventies TPE was used in a variety of diseases in which humoral factors may play a part in the pathogenesis. Today, accepted indications only exist for a few entities in defined situations: Anti-glomerular basement membrane antibody mediated disease, TTP/HUS, Guillain-Barré-syndrome, hyperviscosity syndrome, chronic polyneuropathy associated with IgG and IgA gammopathy, chronic inflammatory demyelinating polyneuropathy and myasthenia gravis.

Autoantibodies↗