PubMed Health⌕ Search

Biomedical subjects

A Schaefer

Publications and source records attributed to A Schaefer.

At least 37 records · Page 2Linked to original sources
PubMed1987

Changes in intracellular pH and cell volume during the early phase of DMSO-induced differentiation of Friend erythroleukemia cells.

Changes in intracellular pH and water volume were measured after treatment of Friend erythroleukemia cells with 1.5% DMSO. It was found that a continuous decrease in pHi occurred, beginning 1 h after induction and a decline in pHi of 0.18 was measured after 9 h. In addition a decline in cellular water volume, of 12% only 15 min after induction, and 23% after 9 h, was observed.

Animals↗
PubMed1987

Plasma amino-acids analysis: effects of delayed samples preparation and of storage.

This paper describes changes occurring in plasma amino-acid concentrations of: samples which are not prepared for analysis immediately after blood collection and samples stored for 5 to 6 months in the form of either plasma, or of deproteinized plasma, or of deproteinized and at pH 2.2 buffered plasma. Results showed that in order to avoid these changes, plasma should be deproteinized and buffered as soon as possible after blood collection. When analysis could not be performed immediately, storage of samples in a freezer at -18 degrees C in the form of deproteinized and at pH 2.2 buffered plasma showed after 5 to 6 months the best recovery of the initial concentrations, but did not exclude all changes.

Amino Acids↗
PubMed1987

[Indications for coronary angiography in patients with acquired heart valve diseases with reference to risk factors].

The aims of the study were to examine the frequency of coronary artery disease (CAD) in patients with acquired valvular heart disease and to investigate the parameters by which significant coronary artery stenosis can be identified without invasive measures in these patients. For this reason 266 consecutive patients with acquired valvular heart disease (aortic, mitral or combined lesions) were examined retrospectively. In 24 patients (9%) a significant (50% or more reduction of the diameter) coronary artery stenosis was found. The prevalence of CAD increased with age: only one patient younger than 50 years, but 23 patients (13%) older than 50 years revealed significant CAD (19% men, 7% women). Increased levels of cholesterol and/or triglycerides were found more frequently in patients with CAD (33% and 29%, respectively) than in those without (6% and 12%, respectively). No differences were found in patients with aortic and mitral valve disease. Patients with typical chest pain revealed CAD in 30% of cases, whereas only 5% of the patients without angina pectoris (or 4% with atypical chest pain) showed a significant coronary artery stenosis. A high percentage (62%) of patients with typical chest pain and mitral valve disease revealed CAD. None of the 77 female patients without typical angina pectoris had significant coronary artery stenosis, whereas 11% of the male patients showed significant CAD even without typical symptoms. In 51 patients without typical angina pectoris and with no risk factors, no CAD was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Influence of medium amino acids on the ouabain sensitive and insensitive 86Rb+-fluxes in HeLa cells.

Components of the 86Rb+-influx in HeLa cells were investigated in Joklik minimal essential medium, or in Earle's balanced salt solution with and without medium amino acids. The presence of amino acids led to the stimulation of the ouabain sensitive 86Rb+-uptake and inhibition of the diuretic-sensitive and residual 86Rb+-fluxes. These results show that the presence of amino acids is an important regulator of the K+/Rb+-fluxes under normal conditions in growth medium.

Amino Acids↗
PubMed1986

Mefenorex (Rondimen).

Mefenorex, N-(3-chloropropyl)-alpha-methylphenethylamine, (RONDIMEN), is included in the list of centrally acting stimulants and/or hallucinogens or related compounds to be considered by a World Health Organization (WHO) Expert Committee in 1985 for possible scheduling under the Convention on Psychotropic Substances, 1971. The therapeutic efficacy of mefenorex as an adjunctive support in the treatment of obesity for limited periods of time, as well as its ability to be well tolerated, has been amply demonstrated. There have been no reports of actual abuse. There have been no reports of illicit trafficking, falsification of packages or materials, or clandestine laboratories manufacturing the compound. Data from preclinical and clinical studies do not suggest a potential for abuse similar to that of amphetamine or related compounds. Moreover, the lack of pulmonary hypertension with mefenorex has been demonstrated in both preclinical and clinical studies. There have been no reports of any public health or social problems associated with mefenorex use. The compound is a well-tolerated anorectic agent with little central stimulant activity.

Adult↗
PubMed1986

Fenetylline: therapeutic use, misuse and/or abuse.

Fenetylline (CAPTAGON) is included in a list of compounds to be considered by a World Health Organization (WHO) Expert Committee in April 1985 for possible international scheduling under the Convention on Psychotropic Substances, 1971. For over 23 years, this central stimulant has been used therapeutically in hyperkinetic children and other indications in place of amphetamines and other central stimulants with higher risk levels. In good correspondence with recent animal data fenetylline also shows significant qualitative and quantitative differences compared to amphetamine in man. It has few adverse side effects, a lower abuse potential and little actual abuse compared to amphetamine. Thus its benefit/risk assessment is substantially more favourable than that of other central stimulants. For proper therapeutic use of the substance, prescription status is or should be required by national authorities.

Aged↗
PubMed1986

Erythroid differentiation and the Na+,K+-pump in ouabain-sensitive and ouabain-resistant Friend erythroleukemia cell lines.

The selection and biochemical characterization of ouabain-resistant erythroleukemia cell lines are described. Treatment of ouabain-resistant Friend erythroleukemia cell (FLC) lines with 1 mM ouabain demonstrated a reduced ouabain-sensitive 86Rb+-uptake after Na+-preloading in comparison with ouabain-sensitive cells. The ouabain- and diuretic (piretanide)-insensitive component of the 86Rb+-uptake (residual influx) was significantly enhanced in the ouabain-resistant FLC clones. Measurements of the Na+,K+-ATPase activity (E.C. 3.6.1.3) in plasma membrane preparations of the ouabain-resistant FLC clone B6/2 indicated that a ouabain-resistant Na+,K+-ATPase activity of about 20% of the total enzyme activity existed in the presence of 1 mM ouabain. Further experiments showed that the Na+,K+-ion-gradient in ouabain-resistant B6/2 cells was unaffected by ouabain exposure whereas the gradient collapsed in wild type 12 N cells. Another property of the ouabain-resistant cell lines was a decrease of the 86Rb+-uptake due to the Na+,K+, 2Cl(-)-cotransport system measured as piretanide-sensitive 86Rb+-uptake. The data on ion transport mechanisms in QuaR and QuaS FLC are discussed with respect to mutagen-induced and spontaneous cellular ouabain resistance. In addition, the role of altered ion transport mechanisms is considered for induced erythroid differentiation.

Animals↗
PubMed1984

Alterations of 86Rb+ fluxes in poliovirus-infected HeLa cells and their dependence on virus replication.

Components of the 86Rb+ influx were investigated subsequent to poliovirus infection in the presence and absence of guanidine-HCl, both under normal steady-state conditions and after Na+ preloading of the cells. Measurements of the ouabain-sensitive 86Rb+ uptake indicated a biphasic change in the activity of the Na+, K+ pump in the course of virus infection: a transient increase in the second hour postinfection, that was detectable only after Na+ preloading and inhibition after 3 hr. The enhanced activity of the Na+, K+ pump was not affected, while the decrease later was fully prevented by the antiviral agent guanidine-HCl. The piretanide-sensitive 86Rb+ uptake due to the Na+, K+, 2 Cl- cotransport system also became strongly inhibited beginning in the second hour postinfection. The inhibition of this transport system was partially antagonized by guanidine-HCl. The remaining 86Rb+ influx in the presence of ouabain and piretanide increased in the third hour postinfection. The latter change in 86Rb+ influx, indicating an increased permeability to monovalent cations was completely abolished by guanidine-HCl.

Biological Transport, Active↗
PubMed1982

Interferon-induced alterations in membrane functions and the growth of Daudi lymphoma and Friend leukemia cells.

The Friend murine erythroleukemia cell system and the Daudi Burkitt's lymphoma cell system were used to study the effect of growth-inhibitory concentrations of interferon on membrane functions. Experiments with Friend-cell clones sensitive and resistant to interferon indicated that a number of changes in membrane transport occur rapidly after the addition of interferon to sensitive cells. While no change was observed in the activity of the (Na+/K+) ATPase in Friend cells sensitive or resistant to interferon, a piretanide-inhibitable Na+,K+, 2Cl- co-transport system was specifically inhibited after interferon treatment of sensitive cells. In contrast, treatment of Daudi cells with purified molecularly cloned or standard preparations of human leukocyte interferon gave rise to no early changes in the transport of amino acids, 32Pi, sugars, or 86Rb+. The major change observed in Daudi cells was a marked reduction in the uptake and incorporation of thymidine, which begins to decrease after 8-10 h of exposure to interferon.

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↗
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↗