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Biomedical subjects

G Sydow

Publications and source records attributed to G Sydow.

At least 37 records · Page 2Linked to original sources
PubMed1982

Tumor promoter-stimulated synthesis of Mason-:Pfizer monkey virus.

The tumor promoter 12-0-tetradecanoyl-phorbol-14-acetate (TPA) increases by severalfold the synthesis of Mason-Pfizer monkey virus (MPMV), a type D retrovirus, when the virus is growing in human embryo kidney (HEK) cells. The effect is transient and paralleled by a striking morphological alteration of the cells. The optimal TPA concentration for stimulation is 5 ng. ml-1. Contrary to infected HEK cells, TPA induces at similar concentrations neither stimulation of MPMV synthesis nor altered morphology in persistently MPMV-infected cells of the continuous human tumor cell line A 204.

Animals↗
PubMed1982

Disintegration of retroviruses by chelating agents.

Exposure in vitro of various mammalian retroviruses to the chelating agents EDTA or EGTA in millimolar concentrations resulted in partial disintegration of viral membranes as measured by accessibility or even release of reverse transcriptase, an internal viral protein, without any other treatment usually required. Among the viruses responding to chelators were mammalian type C viruses, primate type D viruses and bovine leukemia virus. The effect was dose-dependent. The avian type C virus AMV, however, was found to be not susceptible to the agents. Rauscher mouse leukemia virus treated in vitro with EDTA or EGTA showed reduced infectivity in mice. The results are considered as evidence for some association of divalent cations with membranes of mammalian retroviruses. The disintegrating activity of EGTA suggests that Ca2+ is an integral constituent of viruses but Mg2+ may also be involved. These cations seem to be responsible for maintaining integrity of retroviral membranes which, after chelation of ions, are either disrupted or become permeable for the exogenous template of reverse transcriptase. In addition, the disintegrating activity of trifluoperazine may indicate that a calmodulin-like protein occurs in retroviral membranes.

Avian Myeloblastosis Virus↗
PubMed1981

[Phorbol ester-induced expression of primate retroviruses (author's transl)].

Addition of the tumor promoter 12-0-Tetradecanoyl-phorbol-13-acetate (TPA) to the growth medium of certain human cell cultures persistently infected with simian retroviruses of type C (BaEV, SSV) or type D (MPMV) or a human cell line-derived type D isolate (PMFV), respectively, resulted in a considerable but transient stimulation of virus production. Enhanced virus expression was paralleled by striking morphological alterations of the cells. Among four infected cell types tested so far, ony one (A 204) failed to respond to TPA with significant virus stimulation or altered morphology.

Cell Line↗
PubMed1981

[Some parameters of the production of a type D retrovirus (PMFV) in human cells (author's transl)].

The production of a type D retrovirus (PMFV) was analysed using different conditions of cultivation. Both in cell culture flasks and in roller culture bottles with discontinuous change of medium an increase of virus amount was determined within 12 h after seeding of virus-infected cells. Then the virus production considerably fluctuated around an apparent mean value until the end of the experiment at 56 h. In case of a continuous change of cell culture medium in roller bottles a maximum of virus production was measured at a retention time of 24 h of cell culture medium. The production of PMFV could be essentially increased when virus-producing cells were co-cultivated with non-infected cells of the same type.

Cell Line↗
PubMed1980

The protein pattern of PMF virus, a type-D retrovirus from malignant permanent human cell lines.

The protein pattern of a type-D retrovirus (PMFV) isolated from and propagated in human cell lines has been investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Staining with Coomassie blue and labeling with 14C-leucine/14C-lysine revealed five viral polypeptides with molecular weights of 10,000, 12,000, 15,000, 25,000, and 68,000. The 68,000 D-protein was shown to be a glycoprotein by incorporation of 3H-glucosamine and the 15,000 D-protein was identified as a phosphoprotein. By comparing PMFV with the closely related Mason-Pfizer monkey virus (MPMV) in co-electrophoresis experiments no clear difference was detected in viral 14C-leucine/14C-lysine profiles. The viruses differ, however, with respect to their glycoprotein patterns. A glycoprotein corresponding to the gp20 of MPMV has not been detected in PMFV irrespective of the cell line used for propagation of viruses.

Cell Line↗
PubMed1980

Interrelationship of reverse transcriptases of primate type D retroviruses.

Enzyme neutralization experiments by using an antiserum to reverse transcriptase (RT) of Mason-Pfizer monkey virus (MPMV) demonstrated the presence of common antigenic determinants on the RTs of all known type D retroviruses and of determinants discriminating different isolates. The RT of MPMV is antigenically closely related to the RTs of type D viruses isolated from human cell lines although significant differences are also detectable. It shows a lesser degree of relationship to the RTs of squirrel monkey retrovirus (SMRV) and of langur virus (PO-1-Lu). Since the major structural proteins of MPMV and PO-1-Lu are much more related to each other than to the corresponding protein of SMRV it can be concluded that there is no correlation in the degree of relatedness of different proteins of different type D viruses.

Animals↗
PubMed1980

[Activities of several enzymes of glycolysis and of the glucose shunt in the Albert hepatoma of mouse (author's transl)].

The activities of key enzymes of glycolysis and of the glucose shunt as well as the capacity of lactic acid formation were determined in the high-speed tissue supernatant of the transplantable Albert hepatoma of mouse [originally produced by oral application of chrysoidin (2,4-diaminoazobenzene) on C57 Black mice]. Furthermore, the particle-bound hexokinase activity was determined. The following results were obtained: In the hepatoma the activities of aldolase, pyruvate kinase and lactic dehydrogenase are hardly altered compared with normal liver. The activities of hexokinase and phosphofructokinase are increased 2,5-fold, those of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase 2-fold. The capacity for lactic acid formation from glucose is 7 times as high in the hepatoma supernatant. Strong differences emerge from the liver-to-hepatoma relationship in terms of intracellular distribution of the hexokinase (total homogenate 1 : 5, supernatant 1 : 2,5 and particle-bound hexokinase activity 1 : 18). A summarizing consideration of all the results obtained so far for the Albert hepatoma shows that this malignoma departss in several biochemical parameters from the "Molecular Correlation Concept" maintained by Weber, providing more evidence for the individuality of tumors.

Animals↗
PubMed1980

Detection of type D retrovirus in a human amnion cell line (FL).

This paper describes the detection of viral particles in a human amnion cell line (FL). These particles belong to the group of type D retroviruses, because of their characteristic morphology, their major antigenic determinants, and the presence of particle-associated Mg++-preferring RNA-dependent DNA polymerase. In addition to budding and mature type D virus particles, intracytoplasmic type A structures have also been found. Immunological analysis provided evidence of cross-reactivity between the particles described and the Mason-Pfizer monkey virus as well as type D retroviruses from other human cell lines (PMF, HEp-2). Particles isolated from FL cell medium were shown to infect type D virus-susceptible human TU 197 cells.

Amnion↗
PubMed1980

Antiviral effect of haloperidol on Rauscher murine leukemia virus.

The neuroleptic drug haloperidol (Hal) shows, when administered in multiple intraperitoneal or intravenous injections beginning at 5 hrs post inoculation of Rauscher leukemia virus to male NMRI mice, a marked activity in inhibiting virus-induced splenomegaly and prolonging mean survival time. Evidence is presented that a direct action of the drug on the virus is involved in its inhibitory effect.

Animals↗
PubMed1979

Activities of organ characteristic enzymes and noradrenaline and glycogen contents in the Albert hepatoma of C57BL mice.

Further biochemical characterization of the Albert hepatoma has been performed. The following results were obtained: In spite of often repeated transplantations and a medium growth rate, the Albert hepatoma does still contain organ-characteristic enzymes. We have found significant activities of glucokinase, glucose-6-phosphatase and arginase, and considerable amounts of noradrenaline and glycogen. In addition, it is capable to respond to humoral stimuli, that is, it differs from most of the other hepatocellular malignomas also in this regard.

Animals↗
PubMed1979

[A fast and simple micromethod for estimating proteins].

The assay is based on the property of proteins to form a complex with bromophenol blue. In alkaline solution this complex shows an intensive blue colour which is well measurable at 598 nm. The method is especially useful for small volumes (5-50 microliter) with a content of 5-30 micrograms of protein. By modification the test can be also used for the measurement of higher amounts of protein.

Bromphenol Blue↗
PubMed1978

Experiments to increase the selectivity of tumor chemotherapy by means of in vivo activation of transport forms of cancerostatics by exogenous enzymes.

A significant tumor damaging effect (growth inhibition) on transplanted syngeneic sarcoma in mouse was obtained by means of pH-dependent activation of a transport form of a cancerostatic drug by an enzyme foreign to the organism. This effect was achieved by combined administration of 8-0-(alpha-L-arabinofuranosyl)beta-peltatin-A as a transport form of beta-peltatin-A and the exogenous enzyme alpha-L-arabinofuranosidase from Aspergillus niger and additional increase of the acidity of the tumor by injection of glucose. The combined application of the transport form plus enzyme showed a more favorable effect on selectivity than free peltatin when a quantitative comparison was made between the tumor growth inhibition and the damage to the blood picture.

Animals↗
PubMed1977

[Noradrenaline and glycogen content and the activity of several enzymes of carbohydrate metabolism in normal, embryonic, and partly denervated livers and in hepatomas of the rat].

The noradrenaline and glycogen contents as well as hexokinase, glucokinase and glucose-6-phosphatase activities were determined in normal, embryonic and partially denervated (bilateral dissection of the Nervus splanchnicus or Nervus vagus) rat liver and in two transplantable hepatomas. In embryonic liver and hepatomas a strong decrease or complete loss of noradrenaline and glycogen levels and glucokinase and glucose-6-phosphatase activities is demonstrable as compared to the livers of adult animals, while the hexokinase activity is enhanced. Following bilateral splanchnicotomy the glycogen content and hexokinase activity are enhanced; the glucose-6-phosphatase activity is reduced, and the liver does not contain any noradrenaline. Bilateral vagotomy causes decrease of the glycogen content, of the hexokinase and glucokinase activities and an enhancement of glucose-6-phosphatase activity. The results lend support to the idea of antagonistic action of the sympathetic and parasympathetic nervous systems upon several partial reactions of carbohydrate metabolism of liver. In addition, it can be assumed that the alterations of the carbohydrate metabolism demonstrable in hepatomas as compared to normal liver are not solely attributable to disturbance or breakdown of the nervous regulation.

Animals↗
PubMed1977

Selective tumor DNA synthesis inhibition: in vivo prodrug activation by an exogenous enzyme.

Using the combination of alpha-L-arabinofuranosidase from Aspergillus niger with beta-peltatin A-alpha-L-arabinofuranoside, the selective effect of a new cancer of chemotherapy method based on a pH-dependent activation of cancerostatic prodrugs by exogenous enzymes was studied. In comparative experiments the selectivity of prodrug activation was measured by 3H-thymidine incorporation in tumor and normal tissues of CBA mice inoculated im with the transplantable mammary carcinoma, MA-21224. The results show that this special type of carrier principle may lead to a higher degree of selectivity than the usual direct application of cancerostatic drugs.

Animals↗