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Biomedical subjects

A Schaefer

Publications and source records attributed to A Schaefer.

At least 109 records · Page 6Linked to original sources
PubMed1982

Poliovirus-induced alterations in HeLa cell membrane functions.

Protein synthesis, amino acid uptake, membrane potential, cell volume, Na+ and K+ levels, and ATPase (Na+,K+ activated; EC 3.6.1.3) activity were investigated in control and poliovirus-infected HeLa cells. Inhibition of protein synthesis was first observed 60 min postinfection and reached a maximum at 120 min. The onset of protein synthesis inhibition coincided with a decrease in cell volume and with an elevation of ATPase activity in isolated HeLa cell membranes. Some 3 h after virus adsorption, ATPase activity was inhibited, the Na+-K+ gradient of the cell collapsed, both membrane potential-dependent tetraphenylphosphonium ion uptake and amino acid uptake were reduced, and the cell volume increased. These results provide further experimental support for the hypothesis that modification of the cell membrane plays an important role in the strategy of cytopathogenic viruses in the shutoff of host metabolism and cell death.

Adenosine Triphosphatases↗
PubMed1981

Separation of brain-damaged from psychiatric patients with ability and personality measures.

Previous research indicates that many brain-damage screening tests lack the ability to separate organic from functional patients at a satisfactory level. However, the Smith Symbol-Digit Modalities Test, the Benton Visual Retention Test, the Background Interference Procedure variation of the Minnesota Percepto-Diagnostic Test, and the MMPI Psychiatric-Organic Scale have shown some promise in earlier studies. Their abilities to separate brain-damaged patients from five functional samples in a psychiatric setting were compared here. The Smith proved capable of discriminating organics from all functional samples both before and after demographic matching. The Benton and the Minnesota Percepto-Diagnostic Test separated our organics from our functional groups before matching, but results with them after matching were unencouraging. The P-O scale separated the organics from four of the five functional samples before matching and two afterward. The combined use of the P-O and Smith provided a higher level of discrimination than that attained with either alone, correctly identifying 90% of the organics and 79% of the functional Ss.

Adult↗
PubMed1981

Prediction of the WAIS-scores from the 1973 Henmon-Nelson revision.

Administered the 1973 revision of the Henmon-Nelson and the WAIS to 100 psychiatric patients. The correlation of Henmon-Nelson raw scores with WAIS Full Scale scaled score was .83, which compared favorably with correlations run between several other short IQ tests and the WAIS in similar samples drawn from the same setting in earlier studies. However, the Henmon-Nelson did not appear able to estimate the WAIS IQs of low-intelligence Ss or aged persons with consistent accuracy. The validities of short IQ tests and current practices in the selection of WAIS surrogates were discussed.

Adult↗
PubMed1981

Studies on prostaglandin F2 alpha formation caused by pentametylenetetrazol-induced convulsions in rat brain.

Prostaglandin F2 alpha formation caused by pentametylenetetrazol convulsions was studied as a function of the duration, the doses of the convulsant and the intensity of the seizures. It was shown by the statistical analysis of the results in the case of clonic convulsions that the amount of synthetized PGF2 alpha did not depend on the doses of convulsant, while close relation existed between the duration and the PGF2 alpha production. At the same time, during tonic convulsions lasting longer than 50 sec, no more increase in the PGF2 alpha content of the brain was observed. An experimental model is suggested to study in vivo the mechanisms regulating the brain's prostaglandin biosynthesis. Pretreatment of the animals with reserpine did not affect the rate of convulsion-induced PGF2 alpha-formation.

Animals↗
PubMed1980

Rapid bedside estimation of plasma and whole blood lactic acid.

A rapid method for the bedside measurement of plasma, intracellular and whole blood lactates is described. The paper described a new method of measuring the L-lactate content of blood using an apparatus ("Lactate Analyzer 640", manufactured by Roche Bio-electronics, Basel) previously designed for this purpose but using aqueous solutions. A novel feature of this new method is the facility to use small blood samples (100-150 mul). We therefore believe that it will become an invaluable tool in obstetrics and neonatology.

Erythrocytes↗
PubMed1980

Spontaneous activity and food requirements for maintenance and for growth in the genetically obese Zucker rat.

This study was undertaken in order to elucidate whether, as compared with those of their lean controls, the low maintenance requirements of genetically obese Zucker rats may be explained by a lower spontaneous activity. In 6 obese and 6 lean rats, daily body weight, food intake and spontaneous activity were recorded during 6 weeks, using a seismographic recorder. The obese rats weighed more (average + 46%) and ate more (average + 42%) than the lean rats, while there was no difference between their daily activity levels. The relationship between food intake (FI) and weight gain (delta W), both expressed per 100 g body weight, was: FI (kcal/day) = 3.3 delta W (g/day) + 20.4 for lean rats and 4.9 delta W (g/day) + 17.4 for obese rats. Thus, the food requirements for maintenance obtained for delta W = O was less than for obese than for lean rats, while for a given gain in body weight, it was higher for obese rats. This did not seem to be because of a lower daily activity level in the obese than in the lean rats.

Animals↗
PubMed1979

The effects of dietary self-selection upon the overshoot phenomenon in starved-refed rats.

The food intake, liver composition and hepatic activity of pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6P-DH), malic enzyme (ME) and acetyl CoA carboxylase (AcCoA Cx) were studied in starved-refed rats. When rats were refed a mixed diet for 3 days, food intake significantly increased (by 33%) from day 1 to 3 and the glycogen accumulation was maximal after 24 hours, but decreased significantly by day 3 (by 34%). In contrast, liver triglycerides sharply increased (10-fold) from day 1 to 3. Furthermore, during refeeding a large increase of G6P-DH, ME and AcCoA Cx was reached on day 3 when the average activity was 5.5- to 6.5-fold higher than before fasting. When rats were refed under conditions of self-selection (carbohydrates, lipids and proteins) total food intake was the same each day, but lipid and carbohydrate intakes varied reciprocally: lipid intake decreased whereas carbohydrate consumption increased during the 3 day refeeding period. Liver glycogen level was unchanged and both the triglyceride accumulation and the overshoot of lipogenic enzymes were highly attenuated: on day 3, they reached 50% of values observed in mixed diet refed rats. Administration of 8-azaguanine during refeeding under self-selecting conditions lowered food intake but had no effect on the pattern of food intake on the first day. In the following days, lipid intake fell dramatically. Azaguanine does not alter liver glycogenesis, but prevents both liver triglyceride accumulation and the overshoot of lipogenic enzymes.

Animals↗
PubMed1979

In Vitro Binding of Agrobacterium tumefaciens to Plant Cells from Suspension Culture.

In vitro binding experiments were carried out using (32)P-labeled cells of the virulent Agrobacterium tumefaciens strain B6 and Datura innoxia cells from suspension culture. Binding kinetics showed that adherence of bacteria to Datura cells increased gradually during the first 60 minutes and attained a maximum level within 120 minutes of incubation. Maximum binding occurred at pH 6.0. The presence of Ca(2+) and Mg(2+) reduced binding slightly and EDTA had little effect at concentrations of 0.1 to 10 millimolar. The binding of bacteria to Datura cells was temperature-dependent. Escherichia coli, Salmonella typhimurium, Rhizobium japonicum, and Micrococcus lysodeikticus did not compete with virulent A. tumefaciens strain B6 for binding to Datura cells. The admixture of avirulent A. tumefaciens strain IIBNV6 enhanced adherence of virulent A. tumefaciens strain B6 to Datura cells. Octopine had no effect on the binding of virulent A. tumefaciens strain B6 to Datura cells, but 10 millimolar canavanine was inhibitory. Arginine enhanced the adherence of the bacteria at concentrations higher than 0.1 millimolar. Incubation with DNase, RNase, and lipase did not affect the binding, but protease stimulated the adherence of bacteria to Datura cells. Concanavaline A and soybean lectin had little effect whereas lecithin and lysolecithin enhanced binding slightly. Poly-l-lysine markedly stimulated the bacteria-plant cell adherence. Cells from suspension cultures of pea, vetch, and soybean had a 2- to 3-fold higher binding capacity than Datura cells, whereas cells from wheat, corn, rice, and sorghum had a considerably lower affinity for binding with virulent A. tumefaciens strain B6. Bacterial adherence to plant cells was confirmed by autoradiography and electron microscopy. Autoradiographic analysis showed that bacteria were associated with the cell wall, and that often binding of bacteria was localized. Electron micrographs clearly illustrated a tight association of virulent A. tumefaciens strain B6 cells to the Datura cell wall.

Journal Article↗
PubMed1978

[Findings in quality controls of ocean fish in the Siegen district].

In quality tests on traded sea-fish, 30 fresh fish- and 20 quick-frozen fish specimens were tested for their TVB-N content, TMA-N content, as well as for TMAO-N, and were subjected to a sensorial test. Equal portions of codfish- and perch fillets were tested. According to the chemical analytic data, 13 specimens of the fresh fillets proved to be unobjectionable commercial merchandise 17 specimen had to be eliminated as being spoiled, since part of the above values for TVB-N and TMA-N had been considerable exceeded. The results differ enormously between the two species of fish. The perch fillets showed a significant better quality condition than the specimens of codfish. In the sensorial test the objective total result was confirmed in the main. On the basis of the chemical findings one specimen of codfish out of the deep-frozen fillets had to be objected. 16 fillet-specimens could sensorially be approved as being commercially marketable, 4 were tested not for sale. With codfish showing considerable better results than perch.

Animals↗
PubMed1978

Relationships between spontaneous food intake and metabolic activities in the dormouse (Glis glis L.).

1. The relationships between food intake self-selection and liver substrates (glycogen, fat) or activities of pyruvate kinase, glucose-6-phosphate dehydrogenase, malic enzyme, acetyl CoA carboxylase, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase were determined during the spontaneous variations of body weight in the dormouse. 2. The results show that during the phase of increasing body weight, carbohydrate intake and enzyme activities involved in lipogenesis are on a high level. 3. On the last part of the body weight increasing phase, when lipid intake occurs, lipogenesis is depressed and a gluconeogenetic activity is set on, while total caloric intake is important and body weight is still increasing. 4. These metabolic changes are interpreted as a preparation to hibernating conditions in the dormouse.

Animals↗