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R Ulbrich

Publications and source records attributed to R Ulbrich.

32 records · Page 2Linked to original sources
PubMed1979

Activation of fungal alpha-amylase by dithioerythritol.

The activity of fungal alpha-amylase has been shown to be influenced by disulfide-reducing reagents. Thus, the enzymatic activity increases in the presence of dithioerythritol or 2-mercaptoethanol. L-Cysteine is also capable of increasing the activity, but the activation competes with an inactivation reaction which dominates at higher reagent concentrations (greater than 20 mM). A possible scheme interpreting the results is given.

Amylases↗
PubMed1978

The influence of charged matrix surfaces on the thermostabilizing effect of calcium ions on immobilized fungal alpha-amylase.

The stabilizing effect of calcium ions on fungal alpha-amylase (EC 3.2.1.1) immobilized on a polystyrene anion exchanger (P+ amylase) was investigated and compared to the behaviour of soluble amylase. Moreover, gamma-(1,4-benzoquinone-2-yl)-aminopropyl silica-amylase (Si(n) amylase) as a conjugate with weakly basic amino groups and gamma-succinamidopropyl silica amylase (Si- amylase) as a conjugate with free carboxyl groups were applied for comparison. Depending on the calcium ion concentration the immobilized amylases showed a lower thermal stability than the soluble enzyme. The reduced stability was attributed to matrix effects in the microenvironment of the immobilized amylases and the calcium ion concentration in the carrier phase, which was changed in comparison with the external solution. Contrary to the non-measurable matrix effects in the microenvironment, altered calcium ion concentrations in the carrier phase of the polystyrene anion exchanger (P+) and gamma-succinamidopropyl silica (Si-) could be detected. With increasing calcium ion concentration a greater decrease of activity was observed for the soluble amylase than for the immobilized enzymes. The thermal stability of soluble amylase and P+ amylase was studied in dependence on pH. In the acidic pH-range P+ amylase indicated a higher thermal stability than the soluble enzyme in the presence of Ca2+ as well as in the absence of Ca2+. Contrary to soluble amylase the stabilizing effect of calcium ions on P+ amylase begins already at pH 3.5. Kinetic investigations for thermal inactivation were performed on soluble amylase and P+ amylase in the presence and absence of Ca2+ in the temperature range between 44--60 degrees C. Thermal inactivation proceeded by first order reactions. The inactivation rate constants kin served as a measure of thermal stability for discussing the stabilizing effect by Ca2+ depending on the temperature. The activation energies of inactivation EA were determined from the Arrhenius-plot of the inactivation rate constants.

Amylases↗
PubMedDate not supplied

[Measuring subcutaneous fatty tissue as a sonographic parameter for detection of fetal growth retardation and fetal hypertrophy in pregnancy].

This investigation contains a statistical evaluation of sonographic results concerning fetal subcutaneous adipose tissue aiming to examine and assess the relevance of this new sonographic parameter for the detection of fetal growth retardation, resp. fetal hypertrophy during pregnancy. The diagrammatic presentation of the growth of the subcutaneous adipose tissue of eutrophic fetuses shows low validity for the differentiation of hyper- and hypotrophic fetuses. To enable the differentiation between "asymmetric" and "symmetric" types of retardation, the different degrees of growth of the subcutaneous adipose tissue of hypertrophic fetuses have to be taken into consideration. The relation between birthweight and growth of the subcutaneous adipose tissue shows no distinct differentiation of the birthweight, however, presents overlapping categories of the birthweight for diagnostic orientation.

Adipose Tissue↗
PubMedDate not supplied

[Early detection and incidence of iron deficiency in pregnancy].

For early detection of iron deficiency during pregnancy ferritin, transferrin, serum iron, transferrin saturation and red blood cell (RBC) parameters were measured in 156 pregnant women. The geometric mean of ferritin-concentration was 11.7 +/- 2.7 ng/ml (mean +/- 1 s) which is about 46 ng/ml lower than that in non pregnant women. The duration of pregnancy, the number of pregnancies and the interval from the preceding pregnancy were all considered: 67% had iron deficiency, 18% prelatent, 27% latent and 22% manifest. On the basis of RBC analysis only 30% could be detected correctly. Ferritin detected 90% whereas serum iron, transferrin, transferrin saturation only detected 45% of the cases. The serum ferritin level did not correlate with the number of previous pregnancies but it did correlate with the interval to the last pregnancy. Serum ferritin declined sharply until the 28th week of pregnancy but only slightly thereafter. These data suggest at least one determination of serum ferritin concentration in pregnant women for a sufficient prophylaxis of iron deficiency during pregnancy. The latest time for the measurement should be between the 20th and 23rd week. An additional determination of serum ferritin during the early pregnancy is indicated if the time interval to the preceding pregnancy is shorter than three years.

Adolescent↗
PubMedDate not supplied

[Relation between procoagulant activity and fetal lung maturity in amniotic fluid].

A total of 146 samples of amniotic fluid from the 15th to 43rd weeks of pregnancy were taken by either transabdominal amniocentesis or amniotomy during birth. In addition to the palmitic/stearic ratio (P/S) the following coagulation tests were determined: clotting time, modified prothrombin time, partial thromboplastin time (PTT), recalcification time and, in selected samples, thrombelastograms. In the course of pregnancy there is a significant shortening of all coagulation tests measured in amniotic fluid. Comparing the values obtained in the 15th to 18th and the 37th to 43rd weeks of gestation and literature results the following values may indicate fetal maturity: clotting time less than 100 sec., modified prothrombin time less than 80 sec., PTT less than 30 sec. and recalcification time less than 80 sec. The lower limit for P/S ratio in normal pregnancy is 5,0. In 58 cases, amniotic fluid was obtained in the 37th to 43rd week at most 24 hours before delivery; there was no case of RDS in this group. Eliminating intermediate P/S values of 4,5 to 5,0 a false negative rate of 1,7% for the prediction of fetal lung maturity was seen. The corresponding rate for the modified prothrombin time was 3,4% and for the clotting time 6,4%. In 7 RDS cases all cases could be properly predicted from the recalcification time and the PTT. The fetal lung maturity may be estimated by means of simple and rapid coagulation tests and this may facilitate the indication for RDS-prophylaxis. The determination of the L/S or P/S ratios, however, cannot yet be dispensed with.

Amniotic Fluid↗