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Biomedical subjects

A Herrmann

Publications and source records attributed to A Herrmann.

At least 145 records · Page 8Linked to original sources
PubMed1990

Alteration of the aminophospholipid translocase activity during in vivo and artificial aging of human erythrocytes.

Human erythrocytes were separated into three density groups representing different age groups. Phospholipid outside-inside translocation rates and equilibrium distribution were determined in each group with spin-labeled phosphatidylserine (PS*), phosphatidylethanolamine (PE*), and phosphatidylcholine (PC*), at 37 degrees C and 4 degrees C. At both temperatures, the initial velocity of aminolipid translocation was reduced in the more dense (older) cells. The equilibrium distribution was not significantly modified for PS*, but a larger fraction of PE* remained on the outer monolayer of the more dense cells. PC* transmembrane diffusion was identical in the three fractions. Cytosolic ATP, which is required for aminophospholipid translocation, was not responsible for the variability of the density separated cells since ATP enrichment did not cancel the differences between top and bottom fractions, although it equalized the ATP concentration of the various fractions. Variations in the level of intracellular Ca2+ could also be excluded. Thus, the enzyme aminophospholipid translocase seemed to be directly altered in aged cells, possibly due to oxidation caused by lipid peroxidation products. Experiments with malonyldialdehyde or H2O2 treated cells confirmed this interpretation and suggest that defects in endogenous lipid asymmetry observed in aged human erythrocytes may be due to altered activity of the translocase.

Adenosine Triphosphate↗
PubMed1990

Effect of erythrocyte transbilayer phospholipid distribution on fusion with vesicular stomatitis virus.

To identify the specific component(s) in the target membrane involved in fusion of vesicular stomatitis virus (VSV), we examined the interaction of the virus with human erythrocyte membranes with asymmetric and symmetric bilayer distributions of phospholipids. Fusion was monitored spectrofluorometrically by the octadecylrhodamine dequenching assay. Fusion of VSV with lipid-symmetric erythrocyte ghosts was rapid at 37 degrees C and low pH, whereas little or no fusion was observed with lipid-asymmetric ghosts. Conversion of phosphatidylserine in the lipid-symmetric ghost membrane to phosphatidylethanolamine by means of the enzyme phosphatidylserine decarboxylase did not alter the target membrane's susceptibility to VSV fusion. Spin-labeled phospholipid analogues with phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine headgroups incorporated into the outer leaflet of lipid-asymmetric erythrocytes did not render those membranes fusogenic. Electron spin resonance spectra showed an increased mobility of a phosphatidylcholine spin-label incorporated into the outer leaflet of lipid-symmetric erythrocyte ghosts as compared to that of lipid-asymmetric ghosts. These results indicate that the susceptibility to VSV fusion is not dependent on any particular phospholipid but rather is related to packing characteristics of the target membrane.

Electron Spin Resonance Spectroscopy↗
PubMed1990

Protein-mediated phospholipid translocation in the endoplasmic reticulum with a low lipid specificity.

The outside-inside translocation rate of various amphiphilic spin-labeled phospholipids has been measured in rat liver endoplasmic reticulum vesicles. The eight spin-labels tested experienced a fast flip-flop rate with the same half-time of approximately 20 min at 37 degrees C. The stationary distribution of these phospholipid analogues was ca. 45% on the inner vesicular leaflet and 55% on the external one, showing that there is no net enrichment of some lipid in one layer under the experimental conditions used. The initial rate of translocation was reduced 4-fold if membranes were preincubated with N-ethylmaleimide (2 mM) and was about an order of magnitude lower in liposomes made from the extracted lipids. An apparent saturability of the transbilayer diffusion can be deduced from the variation of the initial velocity of the relocation kinetics vs the amount of analogue incorporated in the membrane. Moreover, translocation rates of two different spin-labeled phospholipids introduced simultaneously in the membrane were almost equally reduced by the presence of the other lipid. On the other hand, no competition between the water-soluble dibutyroylphosphatidylcholine and the amphiphilic spin-labeled phospholipids could be detected. Overall, these results suggest that phospholipid translocation in the endoplasmic reticulum is a protein-mediated process with a low specificity, which tends, in the absence of any other metabolic event, to equilibrate the phospholipid composition of the two membrane halves.

Animals↗
PubMed1990

Species-dependent differences in the influence of ionic strength on potassium transport of erythrocytes. The role of membrane fluidity and Ca2+.

The passive Rb+ (K+) efflux from erythrocytes of seven mammalian species was investigated in solutions of physiological and low ionic strength. Furthermore the fluidity of the erythrocyte membrane in the same solutions was estimated by measuring the ESR order parameter. The rate constant of Rb+ (K+) efflux in solution of high ionic strength could be correlated with the order parameter obtained and with the mean number of double bonds to the membrane phospholipid fatty acids. The same relationships could be observed for the low ionic strength solutions if the values for human erythrocytes were excluded. The appearance of Na+, K+, Cl- cotransport to a significant extent, only in human erythrocytes, was supposed to be the reason for this different behaviour of human red blood cells. It was demonstrated that the strong increase of the Rb+ (K+) efflux rate constant for human erythrocytes in low ionic strength solution is not due to Ca2+, as quinine treatment and replacement of all external potassium, both inhibiting the Ca2(+)-induced K+ efflux, did not abolish the increase of (Rb+) K+ efflux in solutions of low ionic strength.

Animals↗
PubMed1990

[Elimination and metabolism of MCT-containing fat emulsions in postoperative patients in the framework of total parenteral nutrition].

Medium chain triglycerides (MCT) may be particularly well-suited for rapid energy supply in postoperative patients because of their rapid availability. We compared the elimination and metabolization of 10% and 20% MCT/LCT-containing infusions (Lipofundin MCT) in 29 non diabetic patients to 10% and 20% LCT-containing infusions during a course of a 7-day TPN. The speed of the provision of triglycerides does not depend on the composition of the fat emulsions. The maximum TG-levels after fat infusion over 12 hours remained under 3 mmol/l. In the MCT/LCT 20% group we found the lowest half-life of the triglycerides with 77 min at the 1st, 133 min at the 4th, and 72 min at the 7th postoperative day. In addition this group showed persistent low half-lives for free fatty acids: 85 min on day 1, 42 min on day 4, and 39 min on day 7. A comparable liberation of fatty acids in corresponding half-lives could be observed in the LCT-groups only after a course of 7 days: 0.86 resp. 0.69 mmol/l (LCT 10% resp. 20%) on day 1, 1.25 resp. 1.26 mmol/l on day 4, and 1.31 resp. 1.97 mmol/l on day 7. The results of the MCT/LCT 20%-group may be due to a quicker metabolization of these emulsions with favourable availability.

Adult↗
PubMed1990

[Electrical impedance and time of death in the animal model].

To study passive electric parameters of the rat skeletal muscles in relation to the time of death, investigations were carried out using the impulse distortion method of Pliquett. This measuring method enables the evaluation of the electric rectangular impulse distorted by the biological tissues, which contains any essential information on the passive electric properties of the object to be measured. The passive electric parameters change in the studied time interval up to 79 h post mortem in a characteristic fashion. The linear correlation of the evaluated impulse parameters at the time of death is closest (r = 0.75) between 0.5-8.5 h post mortem, the scatter of single values in late postmortal periods is in part considerable. A further development of the measuring technique and standardization of the measuring method let the passive electric parameters appear to be appropriate magnitudes for estimating the time of death.

Animals↗
PubMed1990

Effect of a comprehensive health promotion program on employee attitudes.

A 2-year study was conducted to evaluate the effect of a health promotion program on the work-related attitudes of employees. The study employed a quasi-experimental design with nonequivalent control groups. The change in employee attitudes at companies that participated in the program was significantly greater and more favorable than that found at nonparticipating companies. Significant change was found on attitudes toward organizational commitment, supervision, working conditions, job competence, pay and fringe benefits, and job security.

Analysis of Variance↗
PubMed1990

[The clinical relevance of human anti-mouse-antibody (HAMA) in immunoscintigraphy].

Murine monoclonal antibodies (MAb) are applied on a growing scale in radioimmunoscintigraphy (IS) for diagnostic and therapeutic purposes. This increasing use of xenogeneic substances in rapidly growing numbers of patients raises questions of accuracy and reliability of the MAb and also the problem of potential human immunoreaction (human anti-mouse IgG antibodies--HAMA). The aim of this study was to evaluate the clinical relevance of HAMA following IS regarding allergic complications and in vivo effects on IS after repeated applications of MAbs. Out of over 800 immunoscintigraphic examinations performed during the last 5 years in our department 289 studies (in 190 patients) with up to 10 applications (13 different MAbs all together) were considered. Only 1 patient with a high HAMA titer developed a mild allergic reaction (local urticaria) after the 3rd application of an anti-CEA MAb. In 171 intensively documented serum courses following IS, 50 (29%) showed elevated HAMA [1st application: 25/108 (23%); 2nd application: 20/41 (49%): 3rd application: 5/11 (45%); 4th-10th application: no HAMA/11 (2 anti-CEA, 9 Antimyosin)]. Only with strongly increased HAMA values (five times the value before 1st application) there was an altered biodistribution of the MAbs in IS with partially inhibited (8/25 studies with repeated applications) tumor localization. Some patients still demonstrated positive tumor localization despite a HAMA reaction. The problem of HAMA in the diagnostic work-up using MAbs is not the allergic reaction but the potential effects on IS in repeated studies. HAMA should be measured prior to repeated immunoscintigraphic studies.

Animals↗
PubMed1990

[Dermatophyte infections caused by Microsporum canis and Microsporum audouinii in the Greifswald area].

Report of serial diseases of dermatophytoses caused by M. canis (5 patients) and M. audouinii (9 patients). Two cats and a dog were the infective source of M. canis-infection. M. audouinii-infection was stated in a children ward; here the infective source had not been detected. Remarkable are the identical morphological lesions of tinea capitis resp. corporis and the affections of adults in the two groups of patients. Griseofulvin therapy and additional veterinary hygienical treatment in case of M. canis-infection the two endemis were dissipated in few weeks.

Adult↗
PubMed1989

The influence of poly(ethylene glycol) on the molecular dynamics within the glycocalyx.

Interaction of polymers with cell surfaces is a question of general interest for cell aggregation and fusion. The molecular dynamics within the surface coat of human erythrocytes as well as alterations of membrane protein arrangement (IMPs) in the presence of poly(ethylene glycol) (PEG) were investigated by EPR spin labeling techniques and freeze-fracture electron microscopy, respectively. AT PEG concentrations which induce aggregation of erythrocytes the surface coat and the protein arrangement is not disturbed by the polymer. This implicate an exclusion of the polymer from the cell surface.

Cell Aggregation↗
PubMed1989

[The strength of evidence of the food inspection after the Chernobyl accident proven by whole body measurements of Basel students].

The radioactive contamination of the food consumed by the inhabitants of Basel after the Chernobyl fallout has been continuously controlled by our laboratory. The activity of ingested Cs-137 has been estimated and is compared here with the activity obtained through whole body counts. The satisfactory correlation between calculated and observed body activities enables an exact estimation of the people's doses applying the same model and demonstrate the reliability of the food control analysis.

Accidents↗
PubMed1989

[An extended health surveillance program for mentally stressed employees--results and experiences].

One-week physical and psychic fitness training courses are held for nomenclature and management personal annually. Undergoing exercise bouts, they are tested for their cardiocirculatory capacity and given specific information on the type of continuous physical endurance training they should carry out. A follow-up course one year later reviews the level of fitness reached. The follow-up course focuses on a psychologically oriented manager training group talks and concentrative relaxation. Other groups of working people, including shift workers and mothers with several children are given the opportunity to undergo a four-week physical fitness training during preventive spa treatment courses. 140 persons attend this type of treatment every year. For the purpose of objectifying treatment results and reviewing the cardiocirculatory capacity random samples were taken of 20 persons exercising on a fitness machine before, immediately after and six months after the treatment course. Biochemical parameters were also determined. Physical fitness was up between 25 and 50 watts in 72 per cent of the test persons. Under exercise, the blood pressure and the heart rate fell significantly. The LPTT, cholesterol and uric-acid levels in serum were below the initial values. The improved fitness persisted only in 27 per cent of the test persons after six months, with the biochemical parameters equalling the initial values. Preventive measures in the form of physical fitness should be extended at enterprise and local levels. However, working people should be more aware of the possibilities available for physical fitness training.

Humans↗
PubMed1988

The influenza virus-induced fusion of erythrocyte ghosts does not depend on osmotic forces.

The role of osmotic forces and cell swelling in the influenza virus-induced fusion of unsealed or resealed ghosts of human erythrocytes was investigated under isotonic and hypotonic conditions using a recently developed fluorescence assay (Hoekstra, D., De Boer, T., Klappe, K., Wilschut, J. (1984) Biochemistry 23, 5675-5681). The method is based on the relief of fluorescence selfquenching of the fluorescent amphiphile octadecyl rhodamine B chloride (R18) incorporated into the ghost membrane as occurs when labeled membranes fuse with unlabeled membranes. No effect neither of the external osmotic pressure nor of cell swelling on virally mediated ghost fusion was established. Influenza virus fused unsealed ghosts as effectively as resealed ghosts. It is concluded that neither osmotic forces nor osmotic swelling of cells is necessary for virus-induced cell fusion. This is supported by microscopic observations of virus-induced fusion of intact erythrocytes in hypotonic and hypertonic media. A disruption of the spectrin-actin network did not cause an enhanced cell fusion at acidic pH of about 5 or any fusion at pH 7.4.

Erythrocyte Membrane↗
PubMed1988

Asymmetric distribution of phospholipids in spectrin-poor erythrocyte vesicles.

We have investigated by electron spin resonance, at 37 degrees C, the outside-inside passage and the equilibrium distribution of spin-labeled phospholipids, respectively, in ATP-containing ghosts, in heat-treated erythrocytes, and in heat-induced vesicles. The heat-treated vesicles were spectrin depleted to approximately 25% of the original content and had lost almost 100% of the other cytoskeletal proteins. Yet the vesicles, as long as they contained ATP, were capable of translocating the aminophospholipids with the same efficiency as the heat-treated erythrocytes, and almost with the same efficiency as ATP-containing ghosts. In the vesicles, sphingomyelin and phosphatidylcholine analogues underwent a very slow transverse diffusion as in native cells. We conclude that spectrin and other cytoskeleton proteins are not major factors for the establishment and maintenance of phospholipid asymmetry in human erythrocytes, which may be chiefly due to the aminophospholipid translocase activity.

Adenosine Triphosphate↗
PubMed1988

Two alleles of the single-copy chalcone synthase gene in parsley differ by a transposon-like element.

Two types of genomic DNA hybridizing with a chalcone synthase cDNA were isolated from cell suspension cultures of parsley (Petroselinum crispum cv. Mooskrause) and cloned in lambda EMBL4. Their fragmentation patterns with several common restriction enzymes were identical, except for the occurrence of a 927 base pair insertion in one type relative to the other. This insertion is located 538 base pairs upstream of the first of two transcription start sites and has characteristic features of a transposable element. The two types of cloned DNA most likely represent two alleles of a chalcone synthase gene occurring in one copy per haploid parsley genome. The nucleotide sequence and exon-intron structure of the larger allele were determined. Analysis of plants either heterozygous or homozygous with respect to the chalcone synthase gene revealed that both allelic forms were expressed and activated by UV light.

Acyltransferases↗
PubMed1988

Are osmotic forces involved in influenza virus-cell fusion?

The kinetics of the fusion process of unsealed and resealed erythrocyte ghosts with influenza virus (A/PR8/34, A/Chile 1/83) were measured under hypotonic, isotonic and hypertonic conditions using a recently developed fluorescence assay (Hoekstra et al. (1984) Biochemistry 23:5675-5681]. No correlation between the external osmotic pressure and kinetics and extent of fusion was observed. Influenza viruses fuse as effectively with unsealed ghosts as with resealed ghosts. It is concluded that osmotic forces as well as osmotic swelling of cells are not necessary for virus-cell membrane fusion.

Cytoskeleton↗
PubMed1988

[Computerized automatic analysis of the cardiotocogram (results of an international multicenter study].

By means of an international multicentre study (SU, Socialist Republic of Poland, Socialist Republic of Czechoslovakia, GDR) 403 patients with computerized CTG-analysis and 393 patients with visual CTG-analysis in labour were investigated in relation to course of labour and neonatal outcome. The following results were fixed: The computerized CTG-analysis by help of the equipment "robotron-NATALI" is equal the statement of high qualified perinatologists. The computerized CTG-analysis led significantly more frequently in various stages of labour to the diagnosis "prepathological" CTG-pattern (warn signs) in relation to visual CTG-analysis with a significantly higher rate of fetal pH-measurements. That means, that the sensitivity of this method is greater. The safety in frame of electronic supervision of labour is improved. The number of "acut-tocolysis" in various stages of labour for both collectives wasn't significantly too. The rate of caesarean section and the rate of operative vaginally deliveries (forceps, vacuum-extraction) showed in both collectives no significantly differences. The neonatal morbidity (APGAR score, pHUA) matured analogous results in the collective with and without computerized CTG-analysis. A decline of "acidotic" morbidity in the collective with computerized CTG-analysis wasn't mentioned. One stillbirth was found in the collective with visual CTG-analysis. In spite of that computerized CTG-analysis showed no better results in perinatological centres in relation to visual CTG-analysis this method is the basis for very important perinatological aims how computer controlled infusion in connection with termination of labour as well as computer steered tocolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Apgar Score↗