Zeitschrift fur klinische Chemie und klinische Biochemie最新文献

The reaction conditions of the monoiodination of L-diiodothyronine and L-triiodothyronine by nonradioactive iodide have been investigated by separation of the reaction mixture on sephadex G-25 with sodium hydroxide 10 mmol/l as eluent and quantitative iodine estimation in the eluate. When labelling with 125I was performed under optimal conditions, a good yield of chromatographically pure L-triiodothyronine or L-thyroxine was obtained with a specific radioactivity between 2 and 3 Ci/mg. The synthesized labelled hormones were tested by radioimmunoassay. They enable a detection of less than 2 pg T3 and less than 5 pg T4.

An automated method for the analysis of total urinary hydroxyproline using strong cation resin tablets of Hypronosticon is described for use in a clinical laboratory and the results are compared with those obtained by other methods. Even though good recoveries are obtained using the technique described in the present work by adding the internal standards either before or after hydrolysis of urine, the present method gave consistently lower values of urinary hydroxyproline compared with a manual and an automated method.

The elimination of free serotonin (5-hydroxytryptamine) in 24 h urine, from patients with gastric carcinoma before operation and from patients following 2/3 gastrectomy (Billroth II), intestinal- or colon-rectum-resection, was measured using direct quantitative thin-layer chromatographic-fluorometry. By comparison with a heterogeneous control group a lowered elimination of free serotonin was observed in patients with gastric carcinoma and following colon-rectum-resection. The remaining groups showed no significant difference with the control group.

Lactate measurements can be performed within 2-3 minutes after blood withdrawal from the patients by using an electrochemical enzymatic sensor for lactate. The values obtained reflect the actual state of the patient which is not the case with the slow classical method using lactate dehydrogenase and NAD. The sensor is reproducible and the influence of the main reducing substances found in the blood is small enough to be of no clinical significance. Drugs commonly used in intensive care stations have no influence on the sensor. In vitro lactate production of the blood cells has been studied under various conditions. 66 pairs of comparative measurements between the classical method and the lactate sensor resulted in a good correlation coefficient.

The uptake of the shortest six fatty acids (acetic to octanoic) was studied in vitro, using everted segments of rat jejunum. The marked influence of medium-pH and fatty acid chain-length suggests that non-ionic diffusion through the lipoid membrane is quantitatively the most important way of transport, but ionic diffusion through the membrane as well as transport through hydrophilic pores also seem to play a role. Though fatt acids evidently are accumulated in the tissue-fluid, and saturation kinetics, competitive inhibition and sodium- as well as energy-dependence apparently are observed, the transport mechanism is assumed to involve solely passive diffusion, - the concept of a carrier-mediated transport for short and medium chain fatty acids seems improbable.

A continuous flow method is described for the determination of glucose in haemolysates and other materials with hexokinase/glucose-6-phosphate dehydrogenase as reagents. It is a micro-method (20 microliter) which can be used with the 2. generation auto-analyzer. The new method was compared with a hexokinase manual method.

A sample extraction chamber for the determination of O2- CO2- and N2O-concentrations in 50 microliters blood samples by gas chromatography is described. These blood samples can be transferred anaerobically from the ear lobe of a patient or other donor by a doctor or medical auxillary. It is shown that N2O, O2 and CO2 are completely extracted from blood, red cell suspension and HCO3-solutions respectively. When the concentrations of the same sample was repeatedly measured the coefficient of variation was 1.3% for O2 and N2O and 1.2% for CO2.

A radioimmunoassay for the measurement of 3.3',5'-triiodo-L-thyromine (reverse T3, rT3) has been developed. The known limitations of this technique have been overcome by the use of the biologically relevant L-compound for the production of highly specific antisera and for preparing the standard curve. The high sensitivity of the assay (lower limit of detection 20 ng/l serum) was obtained by using 125I-labelled rT3 of maximum specific radioactivity. Mean serum rT3 concentrations for various thyroid states were as follows: Normal subjects: 0.182 mug/l (0,280 nmol/l), hypothyroidism: 0.038 mug/l (0.058 nmol/l), hyperthyroidism: 0.522 mug/l (0.802 nmol/l), pregnants: 0.200 mug/l (0.307 nmol/l), newborn (cord serum): 2.11 mug/l (3.24 nmol/l). The method described should provide additional information with regard to the clarification of thyroxine metabolism.

Km is necessary to calculate the conditions for indicator reactions in coupled enzymic assays. When malate dehydrogenase is used as an indicator enzyme for the assay of aspartate aminotransferase activity, its Km in relation to oxaloacetate is needed. Km (oxaloacetate) of commercially available mitochondrial malate dehydrogenase from pig heart was determined as Km equals 1.65 x 10(-5) mol/1 using the measurement conditions for aspartate aminotransferase according to the preliminary recommendations of the IFCC.

The increasing number of determinations performed by radioimmunoassays necessitates rationalization of the procedures. An analyzer system has been developed in order to fully mechanize double antibody radioimmunoassays, which is essentially composed out of four independently working modules. The samples, in microliter vials, are carried in sample chains of up to 650 links. The first pipetting step is performed by syringes with displacement pistons. Additional reagents are rapidly added by an electronically controlled Hamilton repeating dispenser, which makes shaking procedures for mixing unnecessary. The bound/free separation is achieved discontinuously by use of Nuclepore-filters, which are carried in 3 inches distance (76 mm) by a 35 mm dark leader film. After covering the radioactive filter positions with an adhesive plastic foil from both sides, the film spool is directly inserted into a specially constructed gamma-counter. The results of the evaluation of the efficiency and of the precision of each module are presented in this paper.