Biomedical subjects
Publications and source records attributed to W Gross.
Lp (a) has been determined in 203 patients with thrombosis and/or embolism and in 115 healthy volunteers. The frequency distribution of Lp (a) concentrations in the thrombosis group coincided with that in a healthy reference population. We hence conclude that there is no clinically relevant association between Lp (a) plasma concentrations and the risk of thrombosis.
Recently, polyanion precipitation assays for low-density lipoprotein (LDL)-cholesterol have been found to underestimate their analyte in normolipidemic samples (Siekmeier et al., Clin Chim Acta 1988;177:221-30). Therefore, accuracy, specificity, and interference by nonesterified fatty acids have been studied for three precipitants (obtained by heparin, dextran sulfate, or polyvinyl sulfate precipitation). At normal concentrations of LDL, precipitation is incomplete, whereas it is nearly quantitative at high concentrations of LDL. The polyvinyl sulfate reagent markedly responds to variations in the amount of non-LDL protein present in the precipitation mixture. In the dextran sulfate and the polyvinyl sulfate method, but not in the heparin method, the percentages of LDL precipitated notably increase as the concentration of the polyanion compound is decreased. In either assay, very-low-density lipoproteins, but not high-density lipoproteins, are significantly coprecipitated (dextran sulfate 28%, polyvinyl sulfate and heparin 66%) in a concentration-independent fashion. Increased concentrations of nonesterified fatty acids markedly interfere with the dextran sulfate and polyvinyl sulfate assay, but do not much affect results with the heparin reagent.
The aim of the experiments was the in vitro-investigation of metabolic reactions of human placentae under different oxygen supply, particularly when oxygenation followed a period of hypoxia. A perfusion system was used with both circuits of a whole placenta being recirculated over 2 hours with blood-containing perfusate. In group A 17 placentae were perfused under normoxic conditions; in group B 10 perfusions were carried out under hypoxia. In group C 8 placentae were oxygenated after 60 minutes of hypoxic perfusion. (All results are given in mumol/g wet weight/h). In group B glucose uptake (2.95 +/- 1.11) was slightly increased compared to group A (2.59 +/- 1.68), while lactate production was markedly higher (7.69 +/- 1.04 versus 3.56 +/- 1.53 in group A). Oxygen consumption was smaller under hypoxia. Pyruvate showed no significant changes over the 2 hours in all groups. In group C the results of the first hour resembled those of group B. After reoxygenation these placentae showed a smaller oxygen consumption compared to group A, but the highest glucose uptake (4.35 +/- 0.72), whereas lactate production (5.26 +/- 1.86) was lowered compared to group B. The smaller oxygen consumption could be explained by a deterioration of mitochondriae and hence a decreased capacity of oxydative metabolism. The higher glucose uptake could reflect the ability of placental tissue to restore other energy-sources (e.g. proteins) which were affected under the previous hypoxia. Further investigations are required to answer questions of placental function and its disturbances.
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A new experimental skin-flap model is presented in which direct observations of blood flow in individual capillaries can be made from the time of flap creation throughout the entire evolution of the establishment of necrosis. After flap creation, one observes through the microscope that at 1 hour a large area of tissue is nonperfused as a result of the surgical trauma. This is followed by vasodilatation at 6 hours, resulting in an increase in the area of perfused tissue. At 24 hours, the vasodilatation persists, and the red cells that have entered the tissue during the vasodilatation (6 hours) accumulate in the capillaries, this being reflected by an increased area of nonperfused tissue. This increase continues to 72 hours, at which time the perfusion-nonperfusion interface becomes well defined and remains so throughout the 5-day experiment. Analyses of the relationship between early postoperative capillary perfusion and eventual necrosis are presented. Advantages and disadvantages of this model are listed.
The intracellular distribution of enzymes capable of catalyzing the reactions from phosphoglycolate to glycerate in the bluegreen colored eucaryotic alga Cyanidium caldarium has been studied. After separating the organelles from a crude homogenate on a linear flotation gradient, the enzymes glycolate oxidase and glutamate-glyoxylate aminotransferase along with catalase were present in the peroxisomal fraction (density: 1.23 grams per cubic centimeter). Serine hydroxymethyltransferase was found in the mitochondrial fraction (density: 1.18 grams per cubic centimeter). In contrast to the observations in green leaves of higher plants, the enzymes for the conversion of serine to glycerate (serine-glyoxylate aminotransferase and hydroxypyruvate reductase) were found only in the soluble fraction of the gradient. The partial characterization of enzymes from Cyanidium participating in glycolate metabolism revealed only slight differences from the corresponding enzymes from higher plants. The phylogenetic implications of the observed similarities between the enigmatic alga Cyanidium and higher plants are discussed.
The intracellular distribution of enzymes, participating in the beta-oxidation of fatty acids in the eucaryotic alga Cyanidium has been studied. After separating the organelles from a crude homogenate on a linear flotation gradient, the enzymes enoyl-CoA hydratase, hydroxyacyl-CoA dehydrogenase, and thiolase were present in the mitochondrial fraction (density: 1.19 gram per cubic centimeter). Activity of an acyl-CoA synthetase was found in the mitochondrial fraction as well as in a band where mitochondrial membrane apparently had accumulated (density: 1.17 gram per cubic centimeter). None of these enzymes were present in the peroxisomes (density: 1.23 gram per cubic centimeter). Results from cell fractionation as well as properties of beta-oxidation enzymes indicate a mitochondrial location of fatty acid degradation also in the algae Galdieria sulphuraria and Cyanidioschyzon merolae.
The temporal relations between fetal body movements and associated fetal heart rate accelerations were shown as the ratios of duration of acceleration or acceleration amplitude and the duration of associated fetal body movements in 44 normotrophic and 40 hypotrophic fetuses (body weights within the 6th to 10th percentiles, n = 19, and less than or equal to the 5th percentile, n = 21) between the 36th and 40th gestational weeks. Related to the duration of associated fetal body movements, hypotrophic fetuses proved to have gradually smaller heart rate accelerations than normotrophic fetuses. Moreover, the acceleration parameters duration and amplitude were dependent on the relative duration of fetal body movements. Short fetal body movements were accompanied by fetal heart rate accelerations of relatively highest degree and vice versa. As a consequence, no comparison is possible between temporally different fetal body movements and their associated heart rate accelerations. Of the two acceleration parameters duration and amplitude, the inclusion of the accelerations amplitude in the above mentioned ratio yielded the most obvious results. Taking into consideration that fetuses with intrauterine growth retardation are often in a state of chronic hypoxia, the ratios of acceleration amplitude and durations of associated fetal body movements indicated different degrees of this metabolic situation.
The degree of fetal respiratory and body movements as well as of fetal heart rate reactivity was checked by synchronous ultrasonic and cardiographic monitoring of 18 normotrophic fetuses in the early and late dilation period. Apart from the fetal respiratory movements, which could no longer be observed in the late dilatation period, the degree of fetal body movements remained unaffected during the birth process. In the late dilatation period, the mean amplitude of heart rate accelerations occurring in association with fetal body movements was significantly lower than in the early dilatation period. In the unimpaired normotrophic fetus, however, the reactivity of the fetal cardiovascular system increased during the birth process in relation to the ratio of the amplitude of heart rate accelerations and the duration of associated fetal body movements. Hence, a decrease in fetal heart rate reactivity signals intranatal disturbance of the materno-utero-placento-fetal entity.
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The extent of fetal movements and their reflections in the cardiogramme were studied in 44 normotrophic and 39 hypotrophic fetuses under standardized conditions using real time ultrasound examination of fetal body and respiratory movements and synchronous registration of fetal cardiogrammes from a uterus without labour. Altogether, hypotrophic fetuses exhibited fewer movements than normotrophic fetuses did. Numbers and parameters of accelerations in fetal heart rate occurring in connection with fetal body movements were less marked, too. The acceleration amplitude was particularly significant. Further comparisons between fetuses born with pHa greater than or equal to 7.20 and less than 7.20 or 1- and 5-minute Apgar scores greater than or equal to 8 points and less than or equal to 7 points revealed statistically significant (alpha = 0.05) differences in the frequency of movements and movement-associated accelerations in fetal heart rate only in fetuses with a body weight less than or equal to the 5th weight percentile according to Kyank (n = 21). Fetuses with a body weight between the 6th and the 10th weight percentiles (n = 18) and normotrophic fetuses did not, or did only faintly, reveal these differences. A ratio calculated from the acceleration amplitudes and the durations of associated body movements differed significantly between impaired and unimpaired born fetuses during defined intervals of the duration of fetal body movements.
A group of 20 urinary continent postmenopausal women and two stress incontinent groups in the age of 60-69 and 70-79 years have been examined concerning standardized conditions without and with stress. The measurements using the pneumatic-hydraulic pump perfusion were recorded under standardized conditions. The whole pressure profile without stress decreased with increasing age and with stress incontinence. The maximum urethra closure pressure has been displaced in the distal part of the urethra. The stress profile demonstrated a shortening of the continence zone, a clear decrease of the urethra closure pressure and a bad pressure transmission in the whole urethra, especially in its distal part. These fluctuations make us expect, that there are only a few promising possibilities of conservative treatment in stress incontinent postmenopausal women over 70 years.
Examples of cardiographic reflections of intranatal fetal movements (body movements) in 130 normotrophic and 26 hypotrophic fetuses (body weight less than or equal to 10th percentile) are presented. Labour-synchronous accelerations of fetal heart rate occurred in 95% associated with fetal body movements. About 83% of the body movements associated with fetal heart rate accelerations occurred periodically. Strikingly, labour with fetal body movements resulted in accelerations, whereas labour alone hardly ever produced medium-term heart rate changes or variable decelerations. In contrast to periodical accelerations with associated body movements, periodical accelerations without associated fetal body movements, which are mainly of hemodynamic origin, indicated potential fetal risk. Even with medium-degree or severe variable decelerations in the expulsive period, fetal body movements with associated heart rate accelerations indicated a good actual fetal condition. The importance of cardiogram synchronous real-time ultrasonic examination of intranatal fetal movements is discussed.
Cardiographic reflections of fetal movements were assessed using cardiogram synchronous ultrasonic examination in 44 normotrophic and 40 hypotrophic fetuses with body weights less than or equal to 10th percentile. The study showed that 90% of the fetal body movements were associated with accelerations in fetal heart rate. The degree of associated accelerations depended on the duration of the fetal body movements. In the hypotrophic fetuses the associated heart rate accelerations had a lower amplitude and a relatively longer duration. In impaired fetuses body movements were associated with decelerations in heart rate. Fetal respiratory movements resulted in an increasing beat-to-beat variability in the CTG. This effect did not occur constantly. During prolonged fetal respiratory segments no fetal body movements were observed and vice versa. Possible causes for the association between fetal movements and cardiogram are discussed.
Three precipitation methods for the determination of low density lipoproteins have been evaluated. In n = 113 normolipidemic samples mean LDL-cholesterol levels have been 2.90 mmol/l, 2.77 mmol/l, 3.21 mmol/l after precipitation with heparin, dextran sulfate, and polyvinylsulfate, respectively. As compared to a combined ultracentrifugation and precipitation reference procedure (mean 3.22 mmol/l) two precipitation methods tend to underrate LDL-cholesterol. Elevated plasma triglycerides may interfere with the precipitation of LDL. The clinical relevance of the precipitation procedures has been studied by discriminant analysis in n = 28 consecutive patients admitted for coronary bypass operation and n = 28 controls. The data suggest that, statistically, the determination of LDL-cholesterol with either precipitation method only provides redundant information as in relation to the Friedewald approximation for LDL-cholesterol. Immunologically determined apolipoprotein B proved a better predictor for group separation than either precipitation method.
Apolipoprotein-A-containing lipoproteins have been studied by means of crossed immunoelectrophoresis with intermediate gels. The experiments confirmed the presence in human plasma of lipoprotein particles with both apoA-I and apoA-II (LpA) and of those with apoA-I but no apoA-II (LpAI). Furthermore, they obtained evidence for the occurrence in human plasma of small amounts of lipoproteins containing apoA-II but not apoA-I, apoB, apoC-II, apoC-III or apoE.
A soluble enzyme which catalyzes the transfer of the methyl group from S-adenosyl-L-methionine to the nitrogen atom of pyridine-3-carboxylic acid (nicotinic acid) could be detected in protein preparations from heterotrophic cell suspension cultures of soybean (Glycine max L.). Enzyme activity was enriched nearly 100-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography to study kinetic properties. S-adenosyl-L-methionine:nicotinic acid-N-methyltransferase (EC 2.1.1.7) showed a pH optimum at pH 8.0 and a temperature optimum between 35 and 40 degrees C. The apparent KM values were determined to be 78 microM for nicotinic acid and 55 microM for the cosubstrate. S-Adenosyl-L-homocysteine was a competitive inhibitor of the methyltransferase with a KI value of 95 microM. The native enzyme had a molecular mass of about 90 kDa. The catalytic activity was inhibited by reagents blocking SH groups, whereas other divalent cations did not significantly influence of the enzyme reaction. The purified methyltransferase revealed a remarkable specificity for nicotinic acid. No other pyridine derivative was a suitable methyl group acceptor. To study a potential methyltransferase activity with nicotinamide as substrate, an additional purification step was necessary to remove nicotinamide amidohydrolase activity from the enzyme preparation. This was achieved by affinity chromatography on S-adenosyl-L-homocysteine-Sepharose thus leading to a 580-fold purified enzyme which showed no methyltransferase activity toward nicotinamide as substrate.
Immunosufficiency can be evaluated by Ig secretion subsequent to mitogenic stimulation of human mononuclear cells (MNC). It seems that there are significant differences in immunoglobulin class secreted by these cells when stimulated with various polyclonal activators. The aim of the current study was to analyse these differences. MNC cells was randomly obtained from nine healthy blood donors and were activated by Epstein-Barr virus (EBV), group-A streptococcus (A-ScM), Staphylococcus aureus (SAC), Klebsiella pneumonia (Kleb-M) and pokeweed mitogen (PWM). Significantly increased levels of IgM were recorded after a 7 day incubation followed by stimulation with Kleb-M (6.2 +/- 2.9) and EBV (5.9 +/- 4.5) compared to inactivated MNC (1.6 +/- 1.4), and following 10 days incubation then stimulation by EBV (13.4 +/- 5.5) and Kleb-M (9.9 +/- 4.2) compared to unstimulated cells (2.9 +/- 1.8). Significantly greater IgG levels were achieved following incubation with EBV (3.0 +/- 4.0) and PWM (2.4 +/- 1.3) after 7 days (vs 0.6 +/- 0.4 in unstimulated cells) and by PWM (11.7 +/- 5.3) and Kleb-M (8.8 +/- 3.9, vs 2.3 +/- 2.2) after 10 days. The present data emphasize the significance of merging both mitogen selection and culture duration for acquiring information and high fidelity results of immunoglobulin secretion by polyclonal activators.