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Biomedical subjects

J Arendes

Publications and source records attributed to J Arendes.

At least 19 recordsLinked to original sources
PubMed1979

Differential and selective inhibition of cellular and herpes simplex virus DNA synthesis by arabinofuranosyladenine.

The influence of 9-beta-D-arabinofuranosyladenine (beta araAdo) and of its anomer 9-alpha-D-arabinofuranosyladenine (alpha araAdo) was studied in non-infected cells and cells infected with herpes simplex virus type 1 (HSV-1) and HSV type 2 (HSV-2). alpha AraAdo is a strong inhibitor of proliferation of non-infected cells. Multiplication of HSV-1 and HSV-2 is not affected at all by alpha araAdo, while their growth is strongly inhibited by beta araAdo. alpha AraAdo exerts no effect on the incorporation of dThd into HSV DNA, but blocks the incorporation into host cell DNA. Its anomer, beta araAdo, affects the incorporation rate of both the viral DNA system and the host cell DNA system (the latter one to a lesser extent). alpha AraAMP is incorporated into newly synthesized cellular DNA but not into HSV DNA. Enzymic studies relevant that alpha araATP has no effect on the HSV DNA polymerase system but a high inhibitory potency in the host cell DNA polymerase alpha system. The anomeric form, beta araATP, is a sensitive inhibitor of HSV DNA polymerase while the cellular DNA polymerases alpha and beta are more refractory.

Adenosine Triphosphate↗
PubMed1979

Aggregation of sponge cells. XX. Self-aggregation of the circular proteid particle.

In the extracellular space of the tissue of the sponge Geodia cydonium, circular proteid particles are found which carry as subunits the aggregation factor and a series of glycosyltransferases. Using the technique of velocity sucrose gradient centrifugation, the sedimentation coefficient (S020,w) of the particle-monosomes was determined to be 90. By means of the Svedberg equation a molecular weight of 1.3 . 10(8) daltons could be estimated. The monosomes aggregate in the presence of Ca2+ to higher complexes via disomes, trisomes, and pentasomes. The complexes can be redissociated by dodecyl sulfate but not by EDTA. During the Ca2+-mediated self-aggregation, the particles lose their biological activity with respect to their aggregation promoting function.

Animals↗
PubMed1979

Age-dependent gene induction in quail oviduct. IX. Age-dependent alterations of DNA-bound amino acids.

DNA-amino acids (and DNA-protein) complexes were isolated from oviducts of immature, mature and senescent quails by a procedure which does not involve proteolytic enzymes. The content of DNA-amino acids in the complexes, isolated from animals belonging to three different age classes is almost identical and it amounts to about 10 micrograms/mg DNA. However, the fraction of DNA-amino acids which is resistant to pronase is twice as high in lysates from senescent quails as in those from immature and mature animals. The amount of DNA-bound amino acids is strongly dependent on hormone-induced physiological effects in immature quails. If immature animals were treated with estrogen hormone, which causes in induction both of DNA and RNA synthesis, the level of DNA-bound amino acids increases by 220%. This material has been found to be pronase sensitive which might indicate that the amino acids are present as peptides. Treatment of estrogen-stimulated animals with progesterone or inhibitors of DNA and RNA synthesis antagonizes the estrogen-envoked formation of DNA-associated amino acids. From the data we propose that the amount of proteins and/or amino acids, bound to DNA,is not only age-related but also correlated with the physiological state of DNA in immature and mature animals.

Age Factors↗
PubMed1979

Poly(adenosine diphosphate ribose) synthesis during herpes simplex virus infection.

Immediately after infection of baby hamster kidney cells with herpes simplex virus (HSV), cellular DNA synthesis was blocked, while extensive HSV DNA synthesis began. These dramatic alterations of the control mechanisms for these two DNA synthesizing systems were not accompanied by a change in the poly(adenosine diphosphate ribose) polymerase activity.

Animals↗
PubMed1979

Age-dependent enzymatic poly (A) metabolism in quail oviduct.

The poly(A) metabolism in oviducts from adult and senescent quails has been studied. The incorporation studies by double-labelling of mRNA with [3H]adenosine and [3H]uridine revealed, that after inhibition of transcription by actinomycin D, the incorporation ratio adenosine/uridine increases drastically in adult animals compared with the ratio determined for mRNA from senescent animals. This finding is a hint that in senescent animals the poly(A) stretch of mRNA is shorter than in adult animals. This assumption is supported by the finding that the activity of the extractable poly(A) exoribonuclease is higher in senescent than in adult animals. The activity of poly(A) exoribonuclease is even enhanced after stimulation of senescent animals with progesterone. The activity of the other catabolic enzyme studied, the poly (A) endoribonuclease, as well as the activity of anabolic poly(A) enzyme, the poly(A) polymerase, are almost identical in oviducts from adult and senescent animals. The properties of the catabolic poly(A) enzymes and of the anabolic poly(A) polymerase seem to be identical.

Adenosine↗
PubMed1979

[Age-dependent avidin induction. V. Changes on the level of post-transcriptional modification].

For the elucidation of the age-dependent reduction of the avidin induction in the ovidict of quails, studies on the level of the post-transcriptional events were performed. In estrogen-treated young animals, the extractable activity of DNA dependent RNA polymerase II increases by 145% after progesterone treatment, while in old animals no increase is observed. In the presence of actinomycin D the incorporation ratio [3H] Ado/[3H] Urd into mRNA increases by about 80% in the case of mature animals; this value is drastically lower (15%) using old animals. The activities of the poly(A)-degrading enzymes in oviducts of mature animals are lower than those in old ones. After progesterone treatment the activities of these enzymes increase in oviducts from old animals, while in young quails no alteration is observed. The possible consequence of these findings on the chain length of the poly(A) segment of mRNA is discussed with regard to its translation capacity.

Aging↗
PubMed1979

Additive effects of bleomycin and neocarzinostatin on degradation of DNA, inhibition of DNA polymerase beta, and cell growth.

The interactions of the two antitumor protein antibiotics, neocarzinostatin (NCS) and bleomycin (BLM), were studied on subcellular and cellular levels. BLM and NCS were found to remove thymine from double-stranded DNA. Combination experiments using BLM and NCS together in an assay with isolated DNA revealed an additive effect in splitting. Under limiting concentration conditions, BLM and NCS induce alkali-labile sites in DNA without a subsequent cleavage of the chain. After transfer of BLM- or NCS-treated DNA into an alkaline solution, strand scissions occur. Combination of BLM and NCS results in an additive DNA-cleaving effect, which indicates that the splitting reactions initiated by BLM or NCS are not influenced if the two antibiotics are applied in combination. The DNA polymerase beta is inhibited by BLM (at higher concentrations) and by NCS in a competitive way with respect to DNA. The inhibition constant of BLM and NCS in a combination experiment was found to be the result of the sum of the inhibition constants of BLM and NCS. Using L5178Y mouse lymphoma cells, it was found that cells incubated with both BLM and NCS show "unbalanced growth." The dose-response curves from BLM and NCS have identical slopes; they are characteristic for compounds which selectively inhibit DNA synthesis. By use of isobolograms, it could also be clearly shown that BLM and NCS interact additively.

Animals↗
PubMed1978

Arabinosyl nucleosides. XII. Influence of arabino-furanosylthymine on growth of L5178y cells.

The antibiotic 1-beta-D-arabinofuranosylthymine (araThd) is a potent inhibitor of the growth of mouse lymphoma cells (L5178y). The ED50 concentration was found to be 9.8 muM. The cells die as a consequence of an unbalanced growth. The cytostatic activity of araThd can be abolished by coincubation with dThd and dUrd but not with Urd. At cytostatic concentrations araThd selectively blocks DNA synthesis; RNA- and protein synthesis are unaffected. Intracellularly araThd is rapidly phosphorylated to araTTP. This enzymic phosphorylation does not influence the synthesis of the naturally occuring, related triphosphate dTTP. AraTMP is incorporated into DNA during DNA synthesis; 1 mol of ara-TMP is incorporated/19,500 molecules of dTMP.

Arabinonucleosides↗
PubMed1978

Arabinosyl nucleosides. XIII. Influence of arabinofuranosylthymine on DNA-, RNA- and protein-synthesizing systems in vitro.

The natural metabolite of the sponge Cryptotethya crypta, arabinofuranosylthymine (araThd), is intracellularly phosphorylated to araTTP. The present study demonstrates that araTTP inhibits both isolated DNA polymerases alpha and the DNA polymerase beta from L5178y cells competitively with respect to the analogous substrate dTTP. The affinity of araTTP is higher to the DNA polymerase alpha than to the DNA polymerase beta. The activity of mammalian DNA-dependent RNA polymerases I, II and III as well as the incorporation rate of a protein cellfree system is not affected by high doses of araTTP.

Arabinonucleosides↗
PubMed1978

Degradation and intracellular phosphorylation of showdomycin.

The anti-tumor agent showdomycin is degraded in the presence of 0.05 M NH4HCO3 (pH 8.0) to a compound which carries a negatively charged group. Together with previous data (Darnall et al., 1967) it is suggested that ammonia causes a basic hydrolysis of the maleimide moiety under formation of a maleic acid-like compound. During this modification the C-glycosidic bond is not split. Intracellularly, in mouse lymphoma cells (L5178y), showdomycin is phosphorylated to showdomycintriphosphate, via the mono- and diphosphate stage.

Ammonia↗