Biomedical subjects
Publications and source records attributed to U Becker.
Caudoxirene (cis-3-(1,2-trans-epoxy-but-3-enyl)-4-vinyl-cyclopentene) is a new gamete releasing factor from Perithalia caudata (Sporochnales). Its threshold concentration is found at 30 pmol for gamete release. Multifidene, viridiene and a Z-isomer of caudoxirene were identified as by-products or trace constituents.
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The classical coagulation analyses are performed either by using manual methods or by means of various instruments with a different degree of automation. The introduction of chromogenic peptide substrates which can be split by thrombin has led to the development of photometric assays for PT and aPTT determination independent from the fibrinogen concentration and from its conversion to fibrin. After that, turbidimetric methods for the determination of fibrinogen, thrombin time and batroxobin time have been set up allowing the use of photometry for the determination of the most important hemostaseological parameters. For such purposes a new analytical system (ChromoTimeSystem, Behringwerke AG, Marburg/FRG) based on a special instrument and reagents for chromogenic and turbidimetric methods for coagulation and fibrinolysis has been developed. The ChromoTimeSystem allows to perform by photometry all important tests for coagulation and fibrinolysis. The analytical characteristics of this new system are presented.
Recently, recommendations for the production of thromboplastins have been issued by International Committees (ICSH/ICTH) to achieve a standardization of prothrombin time assays. Following such recommendations we have standardized two new PT reagents based on coagulometric and photometric methods which rely on the same sensitive human placental thromboplastin. Both PT reagents have been optimized especially for use in oral anticoagulant therapy. They offer high sensitivity and reproducibility, accurate lot standardization and therefore internationally comparable values by the expression of the ISI value of each reagent batch.
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In order to elucidate the effect of beta-adrenergic blockade on liver metabolism and haemodynamics, splanchnic oxygen uptake, hepatic removal of indocyanine green (ICG) and splanchnic and systemic haemodynamics were studied in 13 patients with cirrhosis before and 1.5-2 h after an oral dose of 80 mg propranolol. All patients underwent hepatic vein catheterization and had a primed continuous intravenous infusion of ICG. Azygos vein catheterization was performed in six patients. Splanchnic (hepatic-intestinal) oxygen uptake (median control 68 ml/min vs. beta-blockade 56 ml/min, P less than 0.01), azygos venous oxygen saturation (76 vs. 67%, P less than 0.05), ICG clearance (263 vs. 226 ml/min, P less than 0.01), wedged-to-free hepatic vein pressure (16 vs. 13.5 mm Hg, P less than 0.01), hepatic blood flow (1.18 vs. 0.78 l/min, P less than 0.01), cardiac index (3.42 vs. 2.53 l/min . min 2, P less than 0.01), and heart rate (72 vs. 56 beats per min, P less than 0.01) decreased significantly after oral beta-blockade. The hepatic extraction ratio of ICG increased significantly (0.32 vs. 0.45, P less than 0.01), whereas estimated 'intrinsic' ICG clearance (289 vs. 300 ml/min, n.s.), arterial blood pressure, stroke volume, and systemic vascular resistance remained essentially unchanged. The results indicate that besides the well-known cardiovascular effects of propranolol, beta-adrenergic blockade may also reduce hepatic metabolic functions as evidenced by the significantly decreased splanchnic oxygen uptake. The raised hepatic extraction ratio of ICG may be caused by reduction in hepatic blood flow as well as in intrahepatic shunting.
Sixty-seven consecutive outpatients with endoscopically verified duodenal ulcer were randomised to a double-blind treatment with either 10 ml of an antacid suspension (buffering capacity 85 mmol/10 ml, packed in single dosage pads) 1 and 3 h after each meal and at bedtime or cimetidine 400 mg b.i.d. The double-dummy technique was employed. Endoscopy was performed after 4 weeks treatment and, if the ulcer had not healed, after 8 weeks treatment. When ulcer healing had occurred, the patient entered a 1 year follow-up study. The cumulative healing rates after 4 and 8 weeks treatment were 83 and 97% vs. 69 and 94% in the antacid and cimetidine groups respectively. No significant differences were observed between the treatment groups regarding ulcer healing, symptom relief or compliance. Adverse reactions were few and only 3 (9%) patients in the antacid group had to discontinue the treatment due to diarrhoea. Of the cimetidine treated patients, 61% had symptomatic relapse during the 1 year follow-up compared to 71% of the antacid treated patients. There were no significant differences in recurrence rate or time to relapse. The moderate dose antacid treatment used here is efficient, well tolerated, safe, convenient and is a good alternative treatment of the duodenal ulcer patient.
Nd: YAG laser capsulotomy is a well-established method of opening an opacified posterior lens capsule after extracapsular cataract extraction. The most frequent complication following this procedure is a transient rise in intraocular pressure (IOP) occurring during the first few hours following treatment. In most cases the IOP returns to normal within 24 hours. Occasionally, however, it can increase excessively, causing a vision-threatening complication. The prospective study reported here dealt with the pressure elevation in 60 eyes of 60 patients and the characteristics of aqueous outflow in this critical phase. Tonometric and tonographic findings were compared under the influence of topical indometacin and beta-blocker in combination with pilocarpine 2%. Twenty eyes served as untreated controls. Topical indometacin pretreatment had no positive effect on IOP and aqueous outflow, while beta-blocker and pilocarpine 2% prevented a postoperative elevation of IOP.
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Quality assurance (within the larger framework of quality control) is a tool introduced by the new Federal German roentgen ordinance to optimise image quality and dosage in x-ray diagnostics. Over and above this, the new ordinance comprises new regulations governing expert knowledge in radiation protection, as well as changed rules on the use of x-rays and on the licensing or certification of x-ray equipment. In addition, a new dosage concepts has been introduced on the basis of the effective dose on the lines of the recommendations by the IRCP; as a result, the definitions of radiation protection areas and of dosage limit values had to be revised and reworded.
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Prenatal diagnosis of glycogenosis type II was performed by direct assay of acid alpha-glucosidase (EC 3.2.1.20) in chorionic villous biopsy obtained by transcervical cannula aspiration from a pregnancy at risk in the 10th week of gestation. The exact value of the enzyme activity estimated by the use of antibody preparations for purified human liver acid alpha-glucosidase was in the heterozygous range, and so the homozygous enzyme deficiency could be excluded. The subsequent analysis of cells cultured from amniocentesis sampling in the 18th week of gestation resulted in a similar outcome. The study with antibodies showed that in 23 control chorionic villi obtained during gestational ages between 7-13 weeks, 1-15% of the total alpha-glucosidase activity at pH 4.0 were due to renal or neutral enzyme. This indicates that it may be important to employ antibodies for prenatal diagnosis using chorionic villous sampling. A healthy and unaffected boy was born. The biochemical values obtained from an umbilical blood specimen were in accordance with the results of the prenatal diagnosis.
The occurrence of a consumption coagulopathy as well as prethrombotic and thrombotic states are connected with the formation of thrombin. The proteinase acts upon physiological substrates leading to activation products, e.g. fibrinopeptides, platelet factors or thrombin-antithrombin III-complex. For the determination of such products we have developed immunochemical assays, which detect parameters of a direct or indirect action of thrombin in a specific and sensitive manner: 1. ELISA for determination of platelet factor 4; 2. Latex-test for determination of D-Dimer; 3. ELISA for determination of thrombin-antithrombin III complex. Preliminary results from clinical investigations indicate that the determination of these parameters can be valuable for the diagnosis of activation processes of the clotting system.
Three new methods to characterize the function of protein C in plasma are described and compared to established procedures. Two methods make use of a snake venom derived specific protein C activator which allows rapid, sensitive and standardizable assays in plasma without sample pretreatment. The other technique is a two dimensional immunoelectrophoresis in the presence of calcium or EDTA, respectively.
We describe a two-step procedure for APTT that can be performed on photometric devices. It includes preincubation of diluted plasma with ellagic acid and phospholipids and a starting reagent that contains calcium and a chromogenic peptide substrate for thrombin, Tos-Gly-Pro-Arg-pNA. Reaction time is recorded from addition of the starting reagent until thrombin formation occurs, and a prefixed amount of substrate is cleaved. The pattern of sensitivity to clotting factors and heparin was similar to clotting assays and the substrate used did not interfere with the activity of factor Xa. An application of the method was made for the Cobas(R) Bio centrifugal analyzer. Absorbance readings were sent to an external computer and were transformed into reaction times by a computer program. Although the results are independent on fibrinogen concentrations, from kinetic data of the reaction curve fibrinogen concentrations can be estimated. Correlation studies showed good correspondence to clotting methods (r = 0.92, n = 53) as well as an excellent precision (CV 3% for inter-assays, n = 15) and high throughput of samples (greater than 100/h) in the automated assay.
A new method for the determination of the gastrointestinal transit time (TT) is described. The normal range of the TT was 40--95 h in 58 normal subjects. No age or sex variation of the TT was disclosed. In 25 out-patients with the irritable bowel syndrome the TT was determined before and after 3 weeks' treatment with Vi-Siblin. Of these patients, 20% initially showed a prolonged TT; this decreased during treatment with Vi-Siblin. In the patients with normal TT, this remained unchanged during the treatment. Our study suggests that patients with long TT, long intervals between bowel movements, and frequent attacks of colicky abdominal pain may derive benefit from a plant fibre supplement to their diet. The method for the determination of the TT described is well suited to out-patient studies--also in large populations--since it is relatively easy to perform, stool collection is unnecessary, and the method shows good reproducibility.
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