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Biomedical subjects

B Wilke

Publications and source records attributed to B Wilke.

At least 19 recordsLinked to original sources
PubMed2001

Development and evaluation of assays for the determination of total and pancreatic amylase at 37 degrees C according to the principle recommended by the IFCC.

OBJECTIVES: The aim of our study was a) to optimize assays for measurement of total (T-) and pancreatic (P-)amylase at 37 degrees C based on the principle recommended by the IFCC at 30 degrees C, b) to evaluate the analytical performance of these assays in a multicentric study and c) to establish reference intervals for serum and urine for either method. METHODS: Optimized conditions for 37 degrees C were elaborated with regard to substrate concentration, pH, inorganic additives and glucosidase activity. The cleavage pattern of the EPS substrate was studied by HPLC. Liquid ready-to-use reagents for T- and P-amylase were provided to six European laboratories. RESULTS: The assays showed good performance characteristics (median intraassay CVs 1.0% for T- and 1.3% for P-amylase, median interassay CVs 3.0% for either assay, dynamic range 15-fold URL for T- and 30-fold for P-amylase), high correlation with the previous EPS methods (r > 0.996, slope 0.43, intercept < 5 U/L) in serum, heparin plasma and urine and good analytical specificity of the P-amylase assay (residual S-amylase activity 2.4%). Serum reference ranges were found to be 28 to 100 U/L for T- and 13 to 53 U/L for P-amylase (n = 775); URLs in urine were estimated as 490 U/L or 280 U/g creatinine for males and 450 U/L or 380 U/g creatinine for females with total amylase. CONCLUSION: We believe that these assays based on the 30 degrees C IFCC recommendation represent a further improvement in amylase methodology at 37 degrees C and merit broad application in clinical routine.

Amylases↗
PubMed2001

Detection limit, cut-off and specificity of an improved rapid assay for cardiac troponin T.

The performance of an improved version of the troponin T rapid test TROPT Sensitive was investigated in a multicentre evaluation at twelve centres. The detection limit and the cut-off were determined in a method comparison with Elecsys Troponin T using a total of 365 samples from patients with suspected acute coronary syndromes and 91 samples from healthy blood donors or non-cardiological patients. The analytical specificity was determined by measuring 1271 blood samples from blood donors without any myocardial injury. The test cut-off (90% of results positive) is 0.08 microg/L, and the detection limit is about 0.05 microg/L. The analytical specificity of the test is between 99.7 and 99.9%. With its small area of undefined significance between positive and negative results and its high sensitivity and specificity, TROPT Sensitive is very well suited to the reliable detection of troponin T positive patients with acute coronary syndromes.

Biomarkers↗
PubMed2000

A new method for the synthesis of imidazolidinone- and benzimidazolone-containing

A novel acid-catalyzed double nucleophilic addition of bisthiols to heterocyclic bisacetals gives sulfur-containing macrocycles in good yield. Crossover experiments revealed that the acid-catalyzed N-acyl iminium cyclization for the imidazolidinones is reversible. The sulfur atom in the bridge was extruded photochemically, giving new [2.2]heterophanes containing the imidazolidinone and benzimidazolone ring systems. The determined crystal structures for representative members in the benzimidazolone series are also reported.

Journal Article↗
PubMed1999

Soil-based phytotoxicity of 2,4,6-trinitrotoluene (TNT) to terrestrial higher plants

Seed germination and early stage seedling growth tests were conducted to determine the ecotoxicological threshold of 2,4, 6-trinitrotoluene (TNT) in two soils of different properties. Soils were amended up to 1,600 mg TNT kg-1 soil and four representative species of higher plants, two dicotyledons (Lepidium sativum L., common name: cress; and Brassica rapa Metzg., turnip) and two monocotyledons (Acena sativa L., oat; and Triticum aestivum L., wheat), were assessed. Cumulative seed germination and fresh shoot biomass were measured as evaluation endpoints. Phytotoxicity of TNT was observed to be affected by soil properties and varied between plant species. Cress and turnip showed higher sensitivity to TNT than did oat and wheat. The lowest observable adverse effect concentration (LOAEC) of TNT derived from this study was 50 mg kg-1 soil. In contrast to high TNT concentrations, low levels of TNT, i.e. , 5-25 mg kg-1 soil for cress and turnip and 25-50 mg kg-1 for oat and wheat, stimulated seedling growth. Oat was capable of tolerating as much as 1,600 mg TNT kg-1 and demonstrated a potential ability of TNT detoxification in one of the soils tested, suggesting that this plant might be useful in the bioremediation of TNT contaminated soils.

Journal Article↗
PubMed1998

[Grönblad-Strandberg syndrome from the angiological viewpoint].

HISTORY AND CLINICAL FINDINGS: A 42-year-old man was admitted for treatment of peripheral vascular disease in the left leg (stage III of Fontaine). A year before he had undergone a right aortofemoral bypass operation. On admission there was stenosis of the left pelvic axis and bilateral femoral artery occlusion. In addition there were changes in the skin with abnormal folds, loss of elasticity and yellowish spots over the sides of the neck and the flexor surfaces of all large joints. In addition vision in the left eye was impaired. These findings suggested connective tissue disease involving the skin, eye and arterial system. INVESTIGATIONS: Routine haematological tests were normal as were clotting parameters. Serum concentration of GOT, GPT, gamma-GT were slightly increased. There was a dysproteinaemia with raised HDL and LDL levels. Resting electrocardiogram was normal, showing sinus rhythm and left axis deviation. The crurobrachial pressure index was clearly abnormal: 0.6 on the right and 0.5 on the left. Angiography of the pelvic and left arteries revealed long-segment femoral and partial lower-leg occlusions bilaterally. Abdominal sonography indicated diffuse parenchymal calcifications in both kidneys and angioid streaks on bilateral fundoscopy. Skin biopsy showed defects of elastic fibres and perivascular inflammatory infiltration, while capillary microscopy revealed twisting of the capillaries, most of them with normal lumen. These findings taken together indicated pseudoxanthoma elasticum (PXE) or Grönblad-Strandberg syndrome. TREATMENT AND COURSE: A thrombendarterectomy was performed on the left superficial femoral artery, after which the left popliteal artery became palpable, the pressure indices for the left leg were slightly better, and the patient was discharged home without further complications and improved leg perfusion. CONCLUSION: Possible cardiovascular involvement had to be taken into account in patients with PXE, and long-term angiological monitoring is indicated.

Adult↗
PubMed1991

[Determination of beta-N-acetylglucosaminidase and albumin in urine: comparison of methods and effect of gel filtration in human and rat urine].

A new kinetic method for determination of beta-N-acetylglucosaminidase (beta-NAG, EC 3.2.1.30) in human and rat urine with chlorophenol red-NAG as substrate is compared to two other methods with 4-nitrophenyl-NAG and 3-cresol-sulfonphthaleinyl-NAG respectively as substrates. The impact of gel filtration of urinary specimens on the determination of beta-NAG-activity and of low albumin concentrations in urine is described.

Acetylglucosaminidase↗
PubMed1990

[Proliferation of beta cells after syngeneic transplantation of isolated Langerhans cells into the spleens of diabetic rats].

Syngeneic transplantation of cultured and functionally characterized neonatal islet into the spleen of streptozotocin diabetic Lewis rats resulted in long time survival up to 200 days and in plasma glucose levels lower than 9 mmol/l. The daily plasma glucose profile of transplanted rats had shown significantly above that of non diabetic control rats. 200 days after transplantation morphologically intact, insulin containing beta-cells were demonstrable in the spleen, thus demonstrating the long-term survival of functioning islet cells. Proliferation of beta-cells was shown in the transplanted islets. In addition, beta-cell clusters were found which derived from pancreatic ductules transplanted together with the isolated islets into the spleen. Mitose were visible within ductular epithelial cells. The proliferative response of islets after intrasplenic transplantation is probably the result of a long-term stimulation by slightly enhanced plasma glucose values of the transplanted acceptors compared to control animals.

Animals↗
PubMed1989

Ducto-insular proliferation of beta-cells after syngeneic islet transplantation into the spleen of streptozotocin-diabetic Lewis rats.

Syngeneic transplantation of cultured and functionally characterized neonatal islets into the spleen of streptozotocin diabetic Lewis rats resulted in long time survival up to 200 d and in plasma glucose levels lower than 9 mmol/L. The daily plasma glucose profile of transplanted rats had shown significantly above that of nondiabetic control rats. Two-hundred d after transplantation, morphologically intact, insulin containing beta-cells were demonstrable in the spleen, thus demonstrating the long-term survival of functioning islet cells. Proliferation of beta-cells was shown in the transplanted islets. In addition, beta-cell clusters were found that derived from pancreatic ductules transplanted together with the isolated islets into the spleen. Mitoses were visible within ductular epithelial cells. The proliferative response of islets after intrasplenic transplantation is probably the result of a long-term stimulation by slightly enhanced plasma glucose values of the transplant acceptors compared to control animals.

Animals↗
PubMed1989

[Methodologic aspects in cultivating human keratinocytes].

The cultivation of human keratinocytes is an appropriate experimental model for a variety of cell biological, pharmacological and biochemical investigations and the production of in vitro epidermis suitable for grafting since Rheinwald and Green (1975) have established this method. A procedure is described to isolate and culture human keratinocytes using different culture conditions. About 1-2 million epidermal cells could be prepared by trypsinization over night at 4 degrees C from 1-2 cm2 skin. Primary cell cultures seeded on mitomycin C treated NIH 3T3 fibroblasts reached subconfluence after 15-20 days when Eagle MEM was used as culture medium and after 10-15 days of culture using a mixture of Dulbecco's MEM and Ham F12 (3:1). In each case the media were supplemented with different growth factors. Subcultures were seeded on NIN 3T3 feeder cells as well as in collagen or fibronectin coated dish. Multilayered epidermal sheets developed with in 12-15 days of culture.

Cell Division↗
PubMed1985

Dietary effects on (pro)insulin biosynthesis and insulin-degrading activity in islets from sand rats.

Sand rats were fed either a vegetable (vegetable group) or a standard pellet diet. After 14-16 weeks, the normoglycemic subgroup selected (pellet group) from the animals that had been maintained on the standard diet showed a modest increase in body weight. Plasma immunoreactive insulin levels were not significantly increased, but glucose-stimulated insulin release was elevated from islets isolated from sand rats of the pellet group. Insulin biosynthesis was estimated in vitro by measuring [3H]leucine incorporation into (pro)insulin at 1.5 or 15 mmol/l glucose. The rate of (pro)insulin biosynthesis was elevated only at 15 mmol/l glucose in islets from those normoglycemic sand rats fed the pellet diet when compared with islets from the vegetable group. Specific insulin-degrading activity, as determined by measuring degradation of 125I-labeled insulin, was also increased for islets from the pellet group. The metabolic state of these sand rats is thus associated with normoglycemia in vivo, and increased stimulated rates of insulin biosynthesis and degradation in pancreatic islets in vitro.

Animals↗
PubMed1984

Photochemical (PUVA) treatment of isolated rat islets.

Isolated rat islets were irradiated with long-wave ultraviolet light alone or in combination with the photosensitizer 8-methoxypsoralen. The influences on specific beta cell functions were determined with the aim of finding out experimental conditions which allow the use of such islets for transplantation. Short-term effects: Ultraviolet light affected [3H]leucine incorporation into (pro)insulin (5 J/cm2: 53.8%, 10 J/cm2: 41.0% of the controls) and insulin release was slightly reduced. 8-methoxypsoralen enhanced the irradiation effect. Long-term effects: A restoration of irradiation-affected beta cell function was detected after 5 days of culture unless the dose exceeded 2 J/cm2 (0.1 microM 8-methoxypsoralen) or 1 J/cm2 (1 microM 8-methoxypsoralen). After functional restoration islets can be used for transplantation experiments.

Animals↗
PubMed1983

Protection of insulin secretion by magnesium during islet culture: independence of cAMP/or insulin accumulation.

Pancreatic rat islets cultured for 12 days maintained their insulin content and biosynthesis when cultivated at 10 mmol/l glucose. The glucose-induced insulin secretion investigated in a subsequent incubation period was, however, reduced. At a Mg++ concentration of 5.3 mmol/l in the tissue culture medium not only the content and biosynthesis, but also the secretory response of cultured islets remained fully preserved compared to freshly isolated islets. The secretory response of pancreatic islets cultured at 0.8 or 5.3 mmol/l Mg++ for 4 days was neither related to steady state concentrations of cAMP nor connected to the cAMP accumulation in response to IBMX. The results demonstrated that the favourable effect of Mg++ during a culture period on the subsequent insulin release is not directly related to hormone storage, synthesis and/or cAMP-accumulation.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Functional and morphological characteristics of isolated pancreatic islets in tissue culture.

Islets were isolated from the pancreas of female rats by using the collagenase technique. After culturing for 4 days, the islets were taken for measurement of insulin release biosynthesis as well as glucose utilization in subsequent short-time incubations. A low glucose concentration was insufficient to maintain a glucose-stimulated insulin release in vitro. A high glucose concentration had a protecting and restoring effect on the insulin release: ultrastructurally, such islets showed signs of an active biosynthesis in the electron micrograph. The enhancement of Mg++ in the culture medium resulted in an improvement of insulin storage in the islets, accompanied by a well-preserved action of glucose in a subsequent incubation.

Animals↗
PubMed1982

Characterization of beta-cell specific function of isolated pancreatic islets from hyperglycemic C57BL/KsJ-db/db mice.

Isolated pancreatic islets from male hyperglycemic C57BL/KsJ-db/db mice were used to study (pro)insulin biosynthesis, insulin release and insulin content. A diminution of the insulin content to about 36% and of the insulin release (20 mmol/l glucose) to nearly one half was observed, whereas [3H]leucine incorporation into (pro)insulin was increased. Insulin biosynthesis as well as insulin release showed no further increase, when the glucose concentration was increased to 20 or 30 mmol/l. Cultivation of such islets in TCM 199 (10 mmol/l glucose or additionally increased [Mg++] to 5.3 mmol/l) for 48 h resulted in a significant increase of the insulin content and a restoration of the glucose dependent insulin release.

Animals↗