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Biomedical subjects

G Zimmer

Publications and source records attributed to G Zimmer.

At least 145 records · Page 8Linked to original sources
PubMed1984

Sister chromatid exchange in normal and Ph1-positive leukemic cells after mitomycin-C treatment in vitro.

The sister chromatid exchange (SCE) frequency was investigated in normal bone marrow and Ph1-positive cells of chronic myelocytic leukemia (CML) patients with and without mitomycin-C (MMC) treatment in vitro. Even though the spontaneous SCE frequency was found to be significantly lower in CML cells, the absolute SCE values after MMC treatment did not differ between leukemic and normal cells, and this seems to indicate an equilization of SCE rates. However, the fact that leukemic cells with lower spontaneous SCE rates need a further increase of SCE to reach values equal to those of normal cells might indicate a somewhat higher susceptibility of leukemic cells to DNA damage by MMC. This interpretation appears to be confirmed by the fact that the inhibition of cellular proliferation at higher MMC doses considerably reduced the number of leukemic cells that was able to divide twice during a given culture time.

Adolescent↗
PubMed1983

Isolation, purification and characterization of the ATPase complex from the thermophilic cyanobacterium Synechococcus 6716.

The ATPase complex is isolated and purified from membrane vesicles of the thermophilic cyanobacterium Synechococcus 6716 by octyl glucoside and cholic acid by a modification of the procedure for its extraction from spinach chloroplasts. The complex is purified by differential centrifugation and ammonium sulfate precipitation and by gel filtration on Sepharose 6B. The purified fraction, without any phycocyanin contamination, shows ATP hydrolysis activity and Pi/ATP exchange activity of 1564 and 350 nmol X min-1 X mg protein-1, respectively. N,N'-Dicyclohexylcarbodiimide inhibits the ATP hydrolysis activity of this purified fraction. On polyacrylamide gels most typical F1 ATPase polypeptides are identified, but the low-molecular weight polypeptides visible cannot be ascribed to the F0 part of the complex with certainty; non-identified bands around 30 kDa are also present.

Adenosine Triphosphatases↗
PubMed1983

Sister chromatid exchange and proliferation pattern after ultrasound exposure in vivo.

The sister chromatid exchange (SCE) frequency and cell-cycle specific metaphase patterns were investigated in PHA-stimulated lymphocytes in vitro after in vivo exposure of 15 patients to diagnostic ultrasound. No significant differences were found in SCE rates before and after ultrasound exposure. The evaluation of cell-cycle specific metaphase patterns, differentiating cells which passed one, two, or more cell cycles, gave no evidence for a cell-growth inhibitory effect. Since SCE is regarded as a highly sensitive method for the detection of mutagenic effects, our data confirm previous reports on the genetic safety of diagnostic ultrasound.

Adolescent↗
PubMed1982

Bromobimane crosslinking studies in oligomycin-sensitive ATPase from beef heart mitochondria. Mr 31 000 protein crosslinked.

Using a bromobimane fluorescent label the Mr 31 000 protein band oligomycin-sensitive (OS)-ATPase from beef heart mitochondria is shown to become much intensified by 2-mercaptopropionylglycine. In the presence of 3.5 nmol/mg protein of the thiol reagent ATP-Pi exchange activity is increased by 90%. With the fluorescent crosslinking reagent dibromobimane (DB) we show that a new fluorescent peak appears between Mr 50 000 and 60 000. ATP-Pi exchange is very much decreased by DB. The results suggest that for regulation of ATP-synthetase activity sulfhydryl groups in the region of the Mr 31 000 protein(s) play an important role.

Adenosine Triphosphatases↗
PubMed1982

Electron spin resonance studies on the influence of carbocromen on mitochondria and oligomycin-sensitive mitochondrial ATPase.

The action of ethyl 3-(2-diethylaminoethyl)-4-methyl-2-oxo(2H)-1-benzopyran-7-yloxyacetate (carbocromen, Intensain) on the structure of mitochondria from rat liver and bovine heart and on oligomycin-sensitive (OS)-ATPase was studied using the spin labelling method (ESR). Most prominent results were found with the spin label 4-maleimido-2,2,6,6-tetramethylpiperidinooxyl. In bovine heart mitochondria ho/h-1 ratios in repeated scans increased in presence of carbocromen (20--40 mumol/l), indicating a decrease in mobility of the spin label 100. Reduction rates of spin label were comparable in both controls and carbocromen treated samples. Carbocromen under similar conditions had no effect on rat liver mitochondria. In bovine heart mitochondrial OS-ATPase a concentration-dependent increase of mobile parts of the spectra was found. The ATPase activities indicated a substrate inhibition from concentration of about 2.85 mmol ATP onward. As a working hypothesis it is proposed that in the presence of high substrate concentrations, the drug may decrease ATPase activity, an elevation of which may have fatal consequences in myocardial ischemic disease.

Adenosine Triphosphatases↗
PubMed1982

Differentiation of C3b receptors on human lymphocytes, phagocytes, erythrocytes and renal glomerulus cells by monoclonal antibodies.

C3b receptor protein was purified form human erythrocytes by 2 M KBr solubilization and affinity chromatography on C3-coated sepharose. This material served as antigen for raising monoclonal antibodies. To investigate the distribution and antigenetic relationship between the receptors for C3b on human erythrocytes, lymphoid and phagocytic cells, as well as kidney cells three monoclonal antibodies were selected which inhibited the binding of EAC14 degrees 23b to complement receptor-bearing cells. This could be shown for human erythrocytes by inhibiting the immune adherence reaction, for tonsil lymphocytes, Raji cells, and guinea-pig spleen cells by inhibition of rosette formation of these cells with EAC14 degrees 23b, and for human renal glomeruli by blocking of the the adherence of EAC14 degrees 23b to kidney sections. In contrast, these monoclonal antibodies were not capable of inhibiting rosette formation of human granulocytes and monocytes with EAC14 degrees 23b. The antibodies only interfered with the rosette formation, of EAC14 degrees 23bi and EAC14 degrees 23d with Raji cells and tonsil lymphocytes-if at all-at high concentrations, whereas the rosette formation of Raji cells and tonsil lymphocytes with EAC14 degrees 23b was influenced by supernatants of the selected clones up to a dilution of 1:10(3) to 1:10(5).

Animals↗
PubMed1982

Action of local anesthetics on intensity of lipid transition of phospholipids in human red cell membrane.

Anilinonaphthalene-8-sulfonate (ANS) response over a temperature range was measured in red cell membrane under the influence of a series of local anesthetics. Ratios of slopes before (m1) and after (m2) lipid transition temperature were calculated. The sequence of m1/m2 shows a correlation with Ki values of glucose transport in erythrocytes. For some substances, the rates of esterification of cholesterol in microsomal membrane and the clinical effectiveness increase in the same sequence. The present investigations further underline the concept that the penetrating power of the local anesthetics runs parallel with their biological activity.

Anesthetics, Local↗
PubMed1981

Sister chromatid exchange and growth kinetics in untreated acute leukemia.

Sister chromatid exchange (SCE) frequency has been analyses after short-term culture of leukemic bone marrow cells of eight untreated patients with acute leukemia. Compared to normal bone marrow, results show a statistically significant decrease of SCE (p less than 0.001) in euploid as well as in aneuploid leukemias, ranging from 2.11 to 2.97 SCE per metaphase. The different SCE values were not related to contraction status of chromosomes and could not be explained by the age of patients. Therefore, low SCE may be a typical feature of leukemic cells. An examination of growth rates by the SCE technique revealed a high turnover of normal bone marrow cells. About 80% of the cells did not need more than 50 h to run two or three cell cycles. Leukemic cells, however, apparently divided more slowly, which is in good agreement with data obtained by autoradiographic methods.

Acute Disease↗
PubMed1981

Membrane action of tricyclic drugs. Spectroscopic studies of a series of phenothiazines compared with tricyclic antidepressive substances in red cell membrane, using the spin labelling technique.

Previous results were extended by binding studies of drugs on red cell membrane by means of the spin labelling technique. A series of phenothiazines was investigated and compared with several tricyclic antidepressive substances. It was found that phenothiazines at concentrations below 3 mumol/l decisively increase the order parameter of spin label 618, which reports on the interface of the membrane. Thus the fluidity of the interface is decreased. Spin label 616 reports on the hydrophobic membrane interior. Within this hydrophobic phase, the order is decreased by 100 mumol to 1 mmol/l of the phenothiazines. With tricyclic antidepressive substances, a rise of order parameter of spin label 618 is observed, which, however, is less steep. At about 30 mumol/l a maximum is eventually reached. At even higher concentrations of amitriptyline, nortriptyline or imipramine with spin label 616, however, no significant change of order parameter was observed indicating that perturbation of the hydrophobic membrane interior is not sensed. These findings thus corroborate our previous results, revealing that influence of phenothiazines can be measured through the polar and apolar phases of the membrane, while the antidepressive drugs primarily act on the polar phase.

Antidepressive Agents, Tricyclic↗
PubMed1980

Increase of low-molecular weight polypeptides of rat liver mitochondrial membrane by 2-mercaptopropionylglycine.

Having used 2-mercaptopropionylglycine in successful treatment of chronic hepatitis the mode of action of the reagent was further studied in rat liver mitochondrial membrane. Gradient polyacrylamide gel electrophoresis was employed for this purpose. It was found that after incubation of the mitochondria with ADP and 2-mercaptopropionylglycine and isolation of mitochondrial membranes the amount of low-molecular weight polypeptides was significantly increased. These polypeptides belong to the molecular weight ranges of the epsilon-subunits of the mitochondrial ATPase and of the oligomycin binding site. A working hypothesis is formed that the drug may improve anchoring the ATPase molecule at the membrane site. Such mechanism may elucidate previous biochemical findings, and, in particular, underlines the structure-preserving effect of 2-mercaptopropionylglycine in mitochondria.

Amino Acids, Sulfur↗
PubMed1979

ATP contents and condensed configuration of rat liver mitochondria induced by rising ionic strength.

Experiments using shifts in ionic strength between 0.15 and 0.8 mol/l revealed that from 0.3 mol/l KCl onward toward higher concentration condensed mitochondria are observed. Parallel with increasing condensation, the ATP contents were found to rise up to 0.6 mol/l KCl. At 0.8 mol/l KCl already destroyed mitochondria were found. Also, at this concentration of KCl, ATP contents did not rise any longer. The SH reagent 2-mercaptopropionylglycine was effective at about physiological ionic strength only. Up to concentrations of 0.6 mol/l KCl H+/O ratios were not different from the controls at physiological ionic strength, but the effect of valinomycin was effectively reduced by high concentrations of KCl. It is suggested that condensation of mitochondrial structure is correlated with increases in ATP content.

Adenosine Triphosphate↗