Search PubMed⌕ Search

Biomedical subjects

G Fischer

Publications and source records attributed to G Fischer.

At least 577 records · Page 32Linked to original sources
PubMed1978

An improved and simple micro-method of sphingomyelinase assay in leukocytes and urine.

A simple one-vial-method was developed for the quantitative determination of sphingomyelinase activity in human leukocytes and urine, using [14C-methyl] sphingomyelin. The measured activities of healthy control persons show a higher scatter in (n=50) urine (1.2 +/- 0.5 nmol/h . ml urine) than in (n=9) leukocytes (2.15 +/- 0.35 nmol/h . mg protein). Long term tests showed that the enzyme activities in urine can best be correlated to the 24-h-creatinine excretion. A distinct loss of enzyme activity was found in dialyzed urine starting at about the third day; this did not occur in undialyzed urine. The method also shows good reproducibility in micro-tests. It is therefore suitable for screening tests (urine of persons suffering from Niemann Pick disease) and for the prenatal diagnosis of sphingomyelinosis. For one out of two children with symptoms of sphingomyelinosis (hepatosplenomegaly, mental retardation, and neurological deterioration) the diagnosis was confirmed by morphological examination of tissues obtained by biopsy. In both cases leukocytes and urine revealed normal sphingomyelinase activity. These biochemical results in conjunction with the clinical and morphological picture were indicative of type C Niemann-Pick disease.

Adult↗
PubMed1978

[The age dependent distribution and activity of enzyme metabolism in the humeral epiphysis].

In the chondrocytes of the humerus epiphysis and of the articular cartilage of newborn, 8-, 30-, and 60-day-old albino rats, cytochrome c oxidase, arylsulfatase and carbonate dehydratase activity was found. In the transformation zone, the column cartilage and the proximal hypertrophic cells of 30- and 60-day-old animals, cytochrome c oxidase and arylsulfatase are distinctly present. The reaction of carbonate dehydratase is most pronounced in these cell regions of 8-day-old animals. In the mineralization zone we found only small activity of the investigated enzymes. The cells of the opening zone of all age groups demonstrate an additional activity. In the articular cartilage the cytochrome c oxidase is very distinct. The carbonate dehydratase follows with variable reduction and finally the arylsulfatase with only small activity.

Age Factors↗
PubMed1978

[Does a 50-cycle alternating field cause central-nervous effects? (author's transl)].

This project was to provide a further indication for the triggering of central-nervous effects by a 50 - cycle alternating field with a field strength of 5.300 V/m. Previous studies already raised the suspicion of an effector mechanism of this kind: for instance, the nucleus temperature of rats sank under field influence. The same effect is triggered in mice and rats by prescribing centrally stimulating pharmaca. Furthermore, a rise in diastolic blood pressure with a simultaneous drop in heart rate was described for human subjects. We were able to demonstrate the latter effect in laboratory animals (rats). The experiments under consideration resulted in a significant rise in norepinephrine content of the rats' brains following brief exposure of 15 min length. The measured data after 10 d fell highly significantly below those of the untreated controls and remained approximately at this lowered level until the end of field exposure (21 d). Changes in "turn over" of the norepinephrine metabolism of the brain represent an important indicator for the demonstration of the stimulation of central-nervous structures. Our findings therefore substantiate the presented hypothesis of a central-nervous point of attack by electrical energies.

Animals↗
PubMed1978

[Catalytic mechanism of dipeptidyl-peptidase IV].

Dipeptidyl-peptidase IV isolated from pig kidney microsomes catalyses hydrolysis in a number of dipeptidylaryl-amides of types L-AS-L-Ala-R and L-AS-L-Pro-R. Kinetic studies involving two competing substrates suggest the probable existence of a catalytic centre for both groups of substrates. The speed-determining steps in enzymatic hydrolysis differ in the order L-AS-L-Pro-R and L-AS-L-Ala-R. The secondary enzymatic deuterium-isotopic effects in the hydrolysis of L-Ala-L-Ala-2-d1-pNA are fixed at KHM/KDM = 1.24 and VHmax/VDmax = 1.27. The existence of an acyl-enzyme mechanism is considered likely.

Animals↗
PubMed1977

The activator of cerebroside sulphatase. Binding studies with enzyme and substrate demonstrating the detergent function of the activator protein.

1. Sulphatase A (cerebroside sulphatase) (EC 3.1.6.1.) and a 12-fold excess of its physiological activator protein were chromatographed together on Sephadex G-75. The elution buffer was the same as that used in the enzymic degradation of sulphatides. The two proteins were eluted in different peaks indicating that no stable complex formed. 2. Activator protein was incubated with sulphatides under conditions used favouring the sulphatase activity. Incubation solutions were then examined by electrophoresis on a polyacrylamide gel gradient. An one-to-one complex between activator and sulphatides was observed. Half maximal binding occurred with 2.5 nmol of sulphatides together with 1 or 2 nmol of activator in 100 micronl. 3. Cerebrosides as the enzymic degradation products of sulphatides, bind also to the activator protein. A ratio of one-to-one could possibly be obtained at high cerebroside concentrations. The binding to cerebrosides is less specific than that to sulphatides. A 7-fold excess of cerebrosides was necessary for half maximal binding. 4. In a mixture of sulphatides and cerebrosides the formation of the complex with the activator protein is partly inhibited. The total amount of bound lipids changed as the composition of the lipid mixture was varied. In a one-to-one mixture of the two lipids 60% of the total bound lipids are sulphatides and 40% are cerebrosides.

Binding Sites↗
PubMed1977

Paternal age effect in Down's syndrome.

Increasing incidence of Down's syndrome with advancing paternal age for given maternal age has been demonstrated. Comparisons are made between an almost complete Down's syndrome sample from the Copenhagen Metropolitan Area and a randomly selected sample of births from the same area and the same time period. Men above 55 years have a significantly increased risk of getting children with Down's syndrome.

Adolescent↗
PubMed1977

[Evaluation of social status and hemodynamic results four to six years after prosthetic valve replacement (author's transl)].

In 72 patients the professional and social status before and after prosthetic valve replacement was examined. In 60 of these patients the hemodynamic data (cardiac index, stroke volume index, pulmonary arterial pressure at rest and during exercise) were measured. The patients were classified according to their professional training, their last occupation, and their social status before operation. Postoperative changes in professional life and the daily work load were correlated to the hemodynamic results. The study shows that the social status plays a more important role in regaining the professional position postoperatively than the hemodynamic parameter.

Adolescent↗
PubMed1977

[Studies of enzyme distribution in carbohydrate metabolism in humeral periosteum in rats from different age groups].

In the periosteum of newborn, 8-, 30- and 60-day-old albino rats, beta-glucuronidase, beta-galactosidase and succinate dehydrogenase were found. The enzymes of the investigated age groups show remarkable differences in reaction. beta-Glucuronidase reacts distinctly in the cells of the cambium layer of 8- and 30-day-old animals. beta-Galactosidase reacts very differently in the cell layers of the periosteum of albino rats in all age groups. The reaction of succinate dehydrogenase we found above all in the cambium cells, the preosteoblasts and the osteoblasts.

Age Factors↗
PubMed1977

[Investigations on the effect of an electrostatic field free of residual waves on the motility of the mouse (author's transl)].

Comparative investigations were carried out concerning the influence on the motility of mice of different electrobioclimatic conditions (electrostatic field with a residual wave component of 1% and a field strength of 4.500 V/m; pure residual wave component: 32 Vs/s, field strength 120 V/m/ss; electrostatic field established by batteries: initial voltage 900 V, field strength 4.500 V/m; shielded from ambient atmospheric electrical fields: damping efficiency at 99%). The Faraday condition represented the control as absolutely objective physical magnitude. All experimental chambers were positioned under Faraday shields. Following a 20 day period of acclimatization to the unaccustomed surroundings for the animals (adaptation period), we established the previously described electrophysical conditions in the cages for a further period of 20 days (experimental period). The lowest values measured during the daily readings were found in the Faraday cage, resp. in the pure electrostatic field, the highest in the DC-field with residual wave component resp. in the residual wave component alone. We draw the following conclusion from the findings: the pure DC-field apparently does not possess those bioclimatologically decisive importance that has been and is being postulated from several sides. Many of the stimtng effects observed and attributed to the electrostatic field are most probably due to the residual wave component resulting from the high-voltage generators employed.

Animals↗
PubMed1977

[The development of methylcholanthrene-tumors in mice under the environmental influence of various electrobioclimatological conditions (author's transl)].

Comparative analyses of the development rate of a slow Tumor (Methylcholanthrene) in mice were undertaken under conditions of a) an electrostatic field (Field strength 200 V/m, Residual sinus component 0.1%), b) a Faraday cage (Shielding effectivity on atmospheric electrical disturbances: 99%) and c) a laboratory, climatized with conventional methods. The tumor was initiated in each case following a 6-week acclimatisation period to the unaccustomed surroundings. Following this, we observed the appearance rates over a period of 8 months at 14-day intervals. Under customary laboratory conditions these were perceptibly higher than in the electrostatic field or in the Faraday cage. No difference was apparent between the two latter conditions. Any variations in the electrobioclimatological environment can lead to stress reactions resulting in familiar consequences to various defense mechanisms. This allows us to find an explanation for the results otherwise difficult to interpret; for both in the electrostatic field and under shielding from external electrical influences the neoplastic activity was obviously reduced in comparison to normally climatized laboratory conditions. We are continuing the experiments.

Animals↗
PubMed1976

[Studies on optimising rubella virus haemagglutination-inhibitor tests].

Immuno-electrophoretic and serological studies were undertaken to characterise the non-specific serum inhibitor of rubella haemagglutination. The majority of such inhibitor effects come from the beta(1)-lipoproteins. In addition, small inhibitory effects which were due to alpha(1)-lipoproteins were noted in some sera. The result of the tests is influenced less by removing the inhibitor than by conditions of incubation of the serum-antigen mixture, especially pH. The test is more sensitive if it is not performed at optimal pH for haemagglutination.

Hemagglutination Inhibition Tests↗