Search PubMed⌕ Search

Biomedical subjects

K Tempel

Publications and source records attributed to K Tempel.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Comparative studies on the DNA synthesis of rat thymus and spleen cells in vitro under the influence of x rays, UV light and radiomimetic compounds].

In order to further characterize the different repairing behavior of thymus and spleen cells of rats in vitro under the influence of X-rays, UV radiation and methylmethanesulfonate (MMS), the effect of bleomycin (BM), L-cysteine (CY-E), N-ethylmaleimide (NEM), 1-beta-D-arabinofuranosylcytosine (araC), dideoxythymidine (ddT), and novobiocin (NB) on the semiconservative and restorative DNA synthesis as well as on the behavior of DNA under the alkaline elution was studied. The semiconservative DNA synthesis was inhibited by all examined agents except ddT, the restorative DNA synthesis only by NEM, araC, and NB. The stimulation of the restorative DNA synthesis was increased by UV radiation and MMS in spleen cells and by X-rays, BM and CY-E in thymus cells. Under the conditions of alkaline elution, there was a more sensitive reaction of spleen cells than of thymus cells to X-rays, BM and CY-E. The results show that thymus cells are especially qualified for the repair of short chains and spleen cells for the repair of long chains.

Animals↗
PubMed1984

[Differences between spleen and thymus cells of rats with respect to the effects of ethidium bromide on unscheduled DNA synthesis (DNA repair synthesis) and nucleoid sedimentation].

To get further insight into the causes of differences between rat splenic and thymic cells with regard to DNA repair synthesis, scheduled (SDS) and unscheduled (UDS) DNA synthesis as well as nucleoid sedimentation of the cells were investigated under the influence of ethidium bromide (EB, 1-1000 micrograms/ml). - At concentrations of greater than or equal to 25 micrograms/ml, EB inhibited SDS of both cell species and UDS of thymic cells; much higher additions of the drug (greater than 200 micrograms/ml) were needed to diminish UDS of splenic cells, lower EB-concentrations (25-175 micrograms/ml) stimulating the UDS of the splenic cell preparation. - The sedimentation rate of splenic and thymic cell nucleoids within neutral sucrose gradients had a biphasic dependence on the EB-concentrations. As compared to thymic cells however, preincubation of splenic cells with 50-250 micrograms EB/ml resulted in a significant greater (15-30 percent) sedimentation distance. - The results suggest that a relationship exists between the stimulation of UDS and the ability of cells to establish a greater DNA compactness in the presence of EB.

Animals↗
PubMed1981

[DNase II activation in rat liver in the course of acute diethylnitrosamine-induced damage (author's transl)].

Single oral treatment of rats with acutely toxic doses of diethylnitrosamine (DENA) caused a temporary increase of liver-deoxyribonuclease II (DNase II) in homogenate, parenchymal cell, and diverse cell compartments. Highest stimulation resulted in nuclear fraction and cytosol. Due to largely congruent in vitro features, it was suggested that the normal as well as the DENA-activated DNase II were identical. Non-ionic detergents enhanced the enzyme activity only in control samples to a relatively small extent. Suitable conditions of reaction provided, the activation was suppressed by cycloheximide. The results indicated different mechanisms of DNase II activation in the course of an acute DENA-intoxication: 1. release of structurally bound DNase II fractions into cytosol; 2. induction of the enzyme and/or of an effector; 3. enhancement of the nucleus bound enzyme activity by translocation of activated DNase II from cytosolic to nuclear area.

Animals↗
PubMed1980

[Nucleic acid and protein synthesis of splenic lymphocytes of the rat under the influence of mucopolysaccharide-polysulfuric acid-esters (author's transl)].

The influence of three mucopolysaccharide-polysulfuric acid-esters (MPS) of different molecular weight on DNAase II-activity as well as on nucleic acid and protein synthesis of lymphocytes of rat spleen has been investigated in vitro. The results are summarized as follows: 1. DNAase II-activity (bovine spleen) was inhibited by MPS in a competitive manner. 2. At concentrations of greater than or equal to 10 microgram/ml MPS decreased the incorporation of 3H-thymidine and 14C-uridine into the nucleic acids of the cell suspension. 3. Incorporation of 3H-amino-acids into the lymphocytes protein was enhanced when MPS were added at concentrations of > 1 and > 10 microgram/ml, resp. At lower concentrations of the polyanions, a slight inhibition of protein synthesis was shown. 4. In the presence of MPS, incorporation of the radioactively labelled presursors into the acid-soluble fraction of the cells was enhanced. 5. The MPS-effects described increased with the molecular weight of the polyanions. It is suggested that polyanions like MPS may interfere rather non-specifically with cell membranes and with nucleic acid-polymerases.

Amino Acids↗
PubMed1979

[Effects of 6-methyluracil and exogenous nucleic acids on DNA-synthesis of bone-marrow cells of rats following X-irradiation and tretamine or cyclophosphamide treatment (author's transl)].

The in vitro incorporation of 14C-thymidine into DNA of bone-marrow cells as well as DNA content of spleen and thymus of male Wistar rats were increased significantly by 6-methyluracil (within an N-methyl-D-glucosamine-6-methyluracil complex) and/or heterologous, low-molecular nucleic acids, when given therapeutically at doses of 100--250 mg/kg b.w. following i.v. injection of tretamine. Maximum effects were reached as early as two days after the onset of experiment. When tretamine was replaced by X-irradiation or cyclophosphamide, the influence of the 6-methyluracil complex and nucleic acids was less significant. Whereas normal bone-marrow cells and cells damaged in vitro by X-irradiation, tretamine and/or inhibitors of protein synthesis could not be influenced by the 6-methyluracil complex, incorporation of 14C-L-phenylalanine into proteins of bone-marrow cells was enhanced by exogenous DNA or RNA (10--100 micrograms/ml). The present investigations underline the previously drawn conclusions that certain biological alkylating agents, nucleic acids and pyrimidines may interfere to some extent through the reticuloendothelial system.

Animals↗
PubMed1978

Unscheduled DNA-synthesis in UV-irradiated spleen lymphocytes of the rat after whole-body X-irradiation.

Unscheduled DNA-synthesis of UV-irradiated spleen lymphocytes of the rat is inhibited in a dose-dependent manner by total-body X-irradiation. The reaction is observed immediately after exposure and reaches its maximum within 8--16 h. Doses of some rads are detectable. Following sublethal X-irradiation (250 rad), regeneration takes 4--6 weeks. Analogous results have been obtained in rats treated with 2,4,6-triethyleneimino-1,3,5-triazine. Regardless of the action mechanisms, it is concluded from the present results that the inhibition of the unscheduled incorporation of thymidine-3H in splenic lymphocytes is a very sensitive, though not specific expression of impairment of the lymphatic system.

Animals↗
PubMed1977

E1On the effect of 6-methyluracil on mice damaged by 2,4,6-triethylene-imino-1,3,5-triazine or by X-irradiation (author's transl).

Survival time of mice after i.v. injections of 2,4.6-triethylene-imino-1,3,5-trazine (TEM) or total body-X-irradiation (TBI) was increased by 6-methyluraclil (6-MU) when given in food (200 ppm). Under the same conditions, 6-MU decreased the involution of spleen and thymus (as measured by DNA-content and DNase II activity) under the infuence of TEM and enhanced the regeneration of the spleen after TBI. Elevation of DNase I- and protein content of the kidneys and a (short-dated) increase of incorporation of 14C-phenylalamine into microsomes of liver of 14C-orotic acid into RNA of liver and kidney suggest that the influence of 6-MU is mediated at least partly by a specfically anabolic effect.

Animals↗
PubMed1977

[Effects of 6-methyl-uracil upon the phagocytic activity in mice following whole-body X-irradiation OR 2,4,6-triethyleneimino-s-triazine treatment (author's transl)].

1. Phagocytic activity measured by means of the intravasal clearance of a soot dispersion in male NMRI-mice was increased six to ten days after whole-body X-irradiation (640 R) and decreased during the same period after i.v. administration of 2,4,6-triethyleneimino-s-triazine (TEM 2.0 mg/kg). 2. By means of 6-methyl-uracil food admixtures (200 to 400 ppm during 2 or 3 weeks) or by repeated intravenous injections of a N-methyl-D-glucosamine-6-methyluracil complex (62.5 to 250 mg/kg daily during five days), a significant augmentation of the phagocytic index being related to time and dosage was obtained in otherwise untreated mice. Comparable results were seen using cytidine and cytidine-s'-phosphate, whereas guanosine-5'-phosphate remained ineffective. 3. Whilst stimulating effects of 6-methyl-uracil or its N-methyl-D-glucosamine complex on X-irradiated mice were suspended, an increase up to supernormal values of the phagocytic index was produced by the pyrimidine base in animals treated with TEM. In accordance to this the survival rate of lethally X-irradiated mice (960 R) could not be increased; with animals given lethal TEM-doses, however, a significantly increased survival rate was obtained. 4. The present investigations as well as former biochemical analyses confirm the assumption that 6-methyluracil produces its regeneration effects, to some extent at least, by specific pathways influencing the reticuloendothelium. Different results from X-irradiated and TEM-treated mice are referring to the different points of attack of the two noxa.

Animals↗
PubMed1977

[Influence of whole-body X-ray irradiation and 2, 4, 6-triethyleneimino- 1, 3, 5-triazine on the hypnotic effect of hexobarbital in mice (author's transl)].

The hypnotic effect of hexobarbital, measured in male NMRI-mice, was reduced during the first 24 hours after a unique or fractionated whole-body X-ray irradiation with 700 and 1400 R resp. 70 to 280 R and twelve hours after a unique intravenous injection of 16,0 mg tretamine per kilogram of body weight. Immediately after a unique injection of a high dose of tretamine and 24 hours after the last of four applications of 0,25 to 2,0 mg/kg which were repeated each after one day, the sleeping time after hexobarbital was prolonged. 24 hours after fractionated injection of tretamine (0,5 mg/kg each time), the concentration of hexobarbital in the brain showed a significant increase compared with the control animals. These results show that the decreased effect of hexobarbital in the early post-irradiation phase is based on pharmacodynamic processes while the increase of the effect produced by continued administration of tretamine can be explained by pharmaco-cinetic reasons.

Animals↗