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Biomedical subjects

W Rick

Publications and source records attributed to W Rick.

At least 37 records · Page 2Linked to original sources
PubMed1982

[Determination of lipase catalytic activity with 2,3-dimercapto-1-propanol-tributyrate as substrate].

The two point test for the determination of lipase by Kurooka et al. (J. Biochem. Tokyo 81, 361-369 (1977)) was studied in detail. This procedure uses 2,3-dimercapto-1-propanol-tributyrate as substrate and Ellman's reagent as an acceptor for the released thiol groups. The time course of the enzymic hydrolysis of the substrate showed a pronounced lag phase, which can be influenced by sodium glycocholate. There is no proportionality between the quantity of added serum and the concentration of released thiol groups. Preincubation of the sample with the esterase inhibitor, phenylmethylsulphonylfluoride, as recommended by the authors, does not completely inhibit the serum esterase activity. The action of sodium dodecyl sulphate, which is included in the system, is not explained; in the continuous titrimetric test with triolein as substrate, it acts as a powerful lipase inhibitor. Using 104 serum samples, significant differences were found between the results from this method and those obtained by the titrimetric determination of lipase. Possible fundamental improvements of this test system, using thioesters as substrate, are discussed.

Dimercaprol↗
PubMed1982

[Inner ear and diabetes mellitus experimental streptocotocin diabetes in rats].

The histological changes in the inner ear were compared with the hearing ability in insulin deficiency diabetes of rats. 38 LEW-Han-rats were treated with streptocotocin; 34 of these became diabetic, as proved by the glucose tolerance test. 22 rats served as controls. The diabetes was not treated. For a period of up to 440 days the weight, blood glucose and auditory function were controlled in the living animals. Auditory function was tested by means of pinnal reflex of Preyer for a frequency range between 1000 and 20000 cps. With regard to the mean values of frequency, neither a decrease nor a difference between normal controls and diabetic rats was found to any substantial degree. Histological examinations of sacrificed diabetic rats meanwhile showed the well-known changes in the kidneys with microaneurism, thickened basal lamina, mesangial proliferation, and hyaline bodies. The changes in the inner ear, especially in the region of the stria vascularis and lamina spiralis ossea to the ganglion cochleae, were rather discrete, so that no pronounced diminution of the auditory function as a result of restricted metabolism was to be expected. A loss of ganglion cells was seen in the spiral ganglion of the cochlea in correlation with ageing. There was no clear difference between diabetic rats and normal controls. Insulin deficiency diabetes causes severe changes in the vessels, as demonstrated in the kidney. In the inner ear, however, there were no comparable changes, the hearing ability of diabetic rats remaining practically normal.

Animals↗
PubMed1982

[Inner ear and diabetes mellitus diabetic mutant mice].

We observed the course of diabetes in 23 genetically diabetic mice (C 57 BL/KSJ mdb) and in 25 controls (C 57 BL/KSJ). Diabetes was not treated. Histological changes of pancreas, aorta, kidneys, and inner ear vessels were noted. Auditory function was tested by means of the pinnal reflex of Preyer for a frequency range between 4000 and 20000 cps. The diabetic mice developed partly a mild diabetes associated with weight gain, and partly a severe diabetes with a loss of weight. Histologically, the diabetic mice showed (dependent on the duration and degree of severity of the diabetes) progressive mesangial sclerosis and thickening of basal laminas of the glomerula, as well as progressive slight to moderate thickening of the vascular walls of all inner ear vessels. The hearing ability of diabetic mice and of controls diminished with age to a comparable degree. The diabetic mice showed a slightly higher hearing loss for high frequencies, which did not correlate with the extent of thickening of inner ear vessel walls.

Animals↗
PubMed1982

[Determination of lipase with 8-phenyloctanoic acid vinyl ester as the substrate].

The UV-test described by Myrick ((1976) Ph. D. Thesis, Birmingham, AL, USA) for the determination of the catalytic activity of lipase in serum, using 8-phenyloctanoic acid vinyl ester as substrate, was investigated in detail. When tested with sera the assay gave unsatisfactory linearity. For some serum samples, evaluation was impossible, owing to the complete lack of a linear response. The substrate is attacked not only by purified pancreatic lipase, but also by liver esterase, cholinesterase in plasma, and lipoproteinlipase. Attempts to inhibit the interfering esterases with phenylmethylsulphonylfluoride were unsuccessful. Analyses of 102 sera showed no correlation with the results from the titrimetric assay (r = 0.158). Thus the method of Myrick does not provide clinically useful results.

Caprylates↗
PubMed1982

[Determination of the catalytic activity of lipase by the continuous titration method].

Development of a standardized procedure for the titrimetric assay of lipase has been suggested. Comparative studies with triolein und olive oil were therefore undertaken. Optimal conditions, such as pH, substrate and glycocholate concentrations, etc. were determined for the assay with triolein. The results agree with those obtained earlier with olive oil as substrate. Experience with the quality of various reagents used since 1966 is reported. Problems of methodology are then discussed, especially the incomplete characterization and purity of the bile acid preparations, and their effects on the test conditions. A critical analysis shows that two point tests with modifications of the continuous titration cannot give reliable results. Haemolysis and its effect on catalytic activity of lipase are used to illustrate the consequences of the uncritical acceptance of data from the literature. Furthermore, the required sensitivity of the analytical equipment, operational errors, and the uncritical evaluation and interpretation of analytical data are discussed. The first experiments to be performed with the addition of colipase are described, and the question of whether this cofactor should be used routinely for test purposes is considered. The problem of whether lipoproteinlipase can be quantitatively inhibited is discussed. In view of the outlay on apparatus and the time required for the assay, continuous titration is definitely not suitable for routine screening purposes. On the other hand, simpler methods that give reproducible quantitative results have not yet been developed.

Catalysis↗
PubMed1982

[Determination of the catalytic activity of lipase in serum by measurement or estimation of the pH decrease in a triolein emulsion].

In the enzymic hydrolysis of triolein by lipase in serum, hydrogen ions are produced which lead to a decrease in the pH of the test system. The extent of this pH change depends on the catalytic activity of the lipase and on the buffering capacity of the test system. In the method described for the determination of the catalytic activity of lipase in serum, the decrease in pH is measured and recorded potentiometrically. Comparative studies showed a satisfactory correlation of results with those from the continuous titrimetric method. Further studies were performed with a modification of the detection method described by Härtel et al. ((1971) Z. Klin. Chem. Klin. Biochem. 9, 396-397), based on the estimation of the pH decrease from the colour change of an indicator. With operator experience, this test also gives reproducible results for the catalytic activity of lipase in serum.

Emulsions↗
PubMed1980

[Comparison of the effects of natural and synthetic secretin on the exocrine secretion of the human pancreas (author's transl)].

In 16 healthy male subjects the effects of natural and synthetic secretin on the function of the exocrine pancreas were compared. Following; stimulation with secretin in all cases pancreozymin was injected to ascertain normal pancreatic secretory capacity. The methods applied corresponded to those used in the multicenter study of the European Pancreatic Club. No significant differences were found between the results concerning volume of secretion, maximal bicarbonate concentration, maximal bicarbonate output and enzyme secretion rates after stimulation with natural and synthetic secretin, respectively. It is concluded that the synthetic peptide can be utilized in the same way as the natural product in the secretin-pancreozymin-test.

Bicarbonates↗
PubMed1980

[Effects of pentagastrin and heptagastrin on acid secretion in man (author's transl)].

Gastrin analogues are known to stimulate acid secretion with higher potency the more amino acids prolong the peptid chain towards the N-terminal end. In order to compare the response of pentagastrin (Gastrodiagnost, Merck, Darmstadt) and Heptagastrin (HOE 293, Hoechst AG, Frankfurt/M.) in 12 healthy subjects the two peptides were given subcutaneously in doses of 1 microgram/kg, 3 microgram/kg and 6 microgram/kg body weight. Additionally in 8 subjects 1 microgram/kg/h and 2 microgram/kg/h of the gastrins were given intravenously. Gastric content was aspirated under basal and stimulated conditions in portions of 15 minutes, volume (ml) and acid concentration (meq/l) of each fraction was measured and acid secretion (meq/90'), BAO and PAO were calculated. As compared with pentagastrin the dose response curve was shifted to the left, when heptagastrin was given subcutaneously. The amount of acid secretion over a time period of 90 min. was about 17% higher after heptagastrin than after pentagastrin. There was no difference between the peak acid outputs (PAO). Stimulation of acid secretion was prolonged after heptagastrin as compared to pentagastrin. Both gastrins acted similarly on all parameters measured when administered intravenously. Side effects as nausea and dizziness were observed in two subjects of each group.

Adult↗
PubMed1977

Quantitative determination of creatine kinase isoenzyme catalytic concentrations in serum using immunological methods.

For the determination of creatine kinase isoenzyme catalytic concentrations in serum two methods based on immunological reactions are presented: One method uses inhibiting antibodies, which selectively block the activity of creatine kinase M subunits ("Inhibition Test"). This test is used for routine measurements of creatine kinase MB catalytic concentration; Another method uses precipitating antibodies, which allows a quantitative differentiation of creatine kinase isoenzymes MM, MB and BB ("Precipitation Test"). This test is used as a control for the Inhibition Test for the possible presence of creatine kinase BB activities in doubtful cases. Procedures, specificity, correlation and application of these methods are discussed.

Creatine Kinase↗
PubMed1977

[In vitro perfusion of so-called endoprothesis. An experimental study of incrustations on internal splinting plastic tubes (author's transl)].

We have used the method of internal splinting of the ureter (endoprothesis) for the past ten years. Because we observed partial obstruction of the lumen by incrustations and/or fibrin coagula in cases in which the splints had been in place for long periods, we conducted in vitro experiments into the problem. Under constant and variable conditions, urine was perfused through plastic tubes of different materials. Organic and inorganic urine substances and urine pH were analyzed. The materials used were examined with special scanning electron microscopic techniques, and various depositions, especially in comparisons of in vivo and in vitro conditions, were found.

Humans↗
PubMed1976

An improved method for the determination of creatine kinase activity in serum.

An improved method for the determination of creatine kinase activity (EC 2.7.3.2) is described. For the reactivation of creatine kinase serum is first preincubated in the test solution in the presence of dithioerythritol. Then the enzymatic reaction is started by adding creatine phosphate. By optimizing the concentrations in the test solution and by altering the measurement procedure using dithioerythritol as reactivator, the assay is made more sensitive, and a far higher enzyme activity in serum is measured in comparison with other recommended tests. The reaction rate is linear for ten minutes up to 700 U/l. An increase in activity by enzyme dilution was not observed. In this study a sensitivity of detection of 0.9 U/l was achieved. This would be especially advantageous in the detection of the isoenzymes of creatine kinase after chromatography. Within-run precision was 1.2% (CV), day-to-day precision was 2.0% (CV). The test solution is stable for at least 24 hours.

Adenylate Kinase↗
PubMed1976

Gastric and extragastric gastrin release in normal subjects in duodenal ulcer patients, and in patients with partial gastrectomy (Billroth I).

In 10 normal subjects, in 32 patients with duodenal ulcer (DU), and in 11 patients with partial gastrectomy (Billroth I), serum gastrin rose significantly after an oral and intraduodenal test meal. The highest increases were observed in DU patients after the oral as well as after the intraduodenal test meal. After the intraduodenal test meal in 4 normal subjects and in 17 DU patients an increase of gastric acid secretion and serum gastrin was measured. In basal state, after an intraduodenal or an oral test meal, DU patients with normal gastric acid secretory capacity had higher serum gastrin concentrations than DU patients with gastric hypersecretion. There was a good correlation between peak serum gastrin levels after the oral and after the intraduodenal test meal. From these data it is concluded: (1) Intraduodenal application of a test meal results in release of gastrin from extragastric sites. (2) Extragastric gastrin is biologically active. (3) DU patients are able to release more antral and more extragastric gastrin in response to a test meal. Further studies, however, are necessary to show the significance of these findings in the pathogenesis of peptic ulcer disease.

Duodenal Ulcer↗