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Biomedical subjects

R Schindler

Publications and source records attributed to R Schindler.

At least 127 records · Page 7Linked to original sources
PubMed1985

Stimulatory and inhibitory effects of extracts from mammalian cell-cycle mutants on DNA replication in partially lysed cells.

Heat-sensitive (arrested at 39.5 degrees C, multiplying at 33 degrees C) and cold-sensitive (arrested at 33 degrees C, multiplying at 39.5 degrees C) cell-cycle mutants of the P-815-X2 murine mastocytoma line were used for the preparation of cell extracts. These were tested for their effects on DNA synthesis in 'gently lysed cells' (obtained by treatment with 0.01% Brij-58) or 'highly lysed cells' (obtained by treatment with 0.1% Brij-58). Gently lysed cells prepared from proliferating P-815-X2 or mutant cells incorporated [3H]dTTP efficiently, while highly lysed cells exhibited a low level of [3H]dTTP incorporation which was markedly increased by the addition of extracts from proliferating cells. Extracts prepared from arrested mutant cells, however, were found to inhibit DNA synthesis by gently and highly lysed cells prepared from proliferating cells. After return of arrested mutant cells to the permissive temperature, stimulating activity in cell extract reappeared at the time of reentry of cells into S phase. Both stimulatory and inhibitory activities were associated with material(s) of molecular weight above 25 000, but differed in heat sensitivity and in sensitivity to immobilized proteinase and ribonuclease. Extracts from arrested cells counteracted the stimulating effects of extracts from proliferating cells with kinetics suggesting competitive interaction between stimulating and inhibitory factors.

Animals↗
PubMed1985

Control of DNA polymerase alpha, beta and gamma activities in heat- and cold-sensitive mammalian cell-cycle mutants.

Two heat-sensitive (arrested in G1 at 39.5 degrees C) and two cold-sensitive (arrested in G1 at 33 degrees C) clonal cell-cycle mutants of the murine P-815-X2 mastocytoma line were tested for DNA polymerase alpha, beta and gamma activities. After transfer of mutant cells to the respective nonpermissive temperature, DNA polymerase alpha activities decreased more slowly than relative numbers of cells in S phase. Furthermore, numbers of DNA-synthesizing cells decreased to near-zero levels, whereas polymerase alpha activities in arrested cells were as high as 15-40% of control values. After return of arrested cells to the permissive temperature, polymerase alpha activities increased essentially in parallel with relative numbers of cells in S phase. In contrast to the changes in thymidine kinase (Schneider, E., Müller, B. and Schindler, R. (1983) Biochim. Biophys. Acta 741, 77-85), the decrease of polymerase alpha during entry of cells into proliferative quiescence thus appears to be under rather relaxed control, while after return of arrested cells to the permissive temperature the increase in polymerase alpha is tightly coupled with reentry of cells into S phase. For DNA polymerase beta and gamma activities, no obvious correlation with changes in the proliferative state of cells was detected.

Animals↗
PubMed1985

Proliferative quiescence of normal mast cells resembles that of cold-sensitive mutant mastocytoma cells. Dominant expression of the quiescent state in heterokaryons.

Normal murine peritoneal mast cells were fused to serum-deprived, non-proliferating cells of a cultured subline (41-SB-4) of the P-815 murine mastocytoma. Upon reincubation in medium containing 10% horse serum for 48 h, mono- and binuclear 41-SB-4 cells reentered S phase of the cell cycle, while mast cell X 41-SB-4 heterokaryons as well as mono- and binuclear mast cells remained in proliferative quiescence, indicating dominant expression of the quiescent state of mast cells. The quiescent state of normal mast cells thus resembles that of cold-sensitive (cs) mutant cells (21-F) of the undifferentiated P-815 mastocytoma: at the non-permissive temperature of 33 degrees C, the 21-F cells were found to enter a state of quiescence which is characterized by its dominant expression in heterokaryons and by morphological differentiation with the formation of metachromatically staining granules similar to those of mast cells. This suggests that the cellular control mechanisms involved in entry into proliferative quiescence and in morphological differentiation of cs 21-F cells may be analogous to those of normal mast cells and/or their precursors.

Animals↗
PubMed1985

Faithful cell-cycle regulation of a recombinant mouse histone H4 gene is controlled by sequences in the 3'-terminal part of the gene.

We have analyzed the expression of endogenous histone H4 genes and of a newly introduced H4 gene in 21-Tb cells, a mouse mastocytoma cell-cycle mutant. Endogenous H4 mRNAs were less abundant by a factor of 120-180 in G1-arrested than in exponentially multiplying cells. However, H4 transcription rates were only decreased by a factor of 3 under these conditions, as determined by in vitro elongation of nascent transcripts. This indicates that post-transcriptional control of histone mRNA levels is important, in accord with published data. We introduced a mouse H4 gene, modified by a 12-base-pair (bp) insertion in its coding sequence, into 21-Tb cells by DNA-mediated gene transfer. The levels of transcripts from this gene were regulated in parallel with those of the endogenous genes. Moreover, fusion of the simian virus 40 (SV40) early promoter to a 463-bp fragment containing the 3'-terminal half of the mouse H4 gene, including 230 bp of spacer sequences, led to the regulated expression of SV40/H4 fusion RNA. However, a small proportion of SV40-initiated transcripts were not processed to histone-specific 3' ends, but extended farther through the downstream Escherichia coli galactokinase gene to a SV40 polyadenylylation site. In contrast to the short SV40/H4 RNA, the levels of these longer transcripts were not reduced in G1-arrested cells. These results show that sequences in the 3'-terminal part of the H4 gene can regulate gene expression in the cell cycle, presumably at the post-transcriptional level, as long as they are not positioned much more distant from the terminus than normal.

Animals↗
PubMed1985

Comparison between three fluorometric micromethods for determination of vitamin A in serum.

Three common micromethods for vitamin A1 determination were applied to blood, and compared with each other. Methods under investigation were: silicic acid column technique described by Pollack et al [16], HPLC procedure published by de Ruyter and de Leenheer [6, 7] and correction formula method according to Thompson et al [20]. The serum levels of vitamin A were measured in 51 fasting individuals. The average overall agreement was 104% and 116% of the HPLC value for the silicic acid column technique and for the correction formula method, respectively. The mean values obtained by the three methods do not differ significantly. Using these techniques simultaneously, however, in some cases serum values for the same sample show wide differences. Although vitamin A is usually present in biological samples both as retinol and as retinyl esters, the simple correction formula method does not distinguish between them. Their separate estimation, however, can be achieved by different chromatographic procedures. The HPLC method therefore used offers several advantages over the described silicic acid column technique. This technique includes fluorescence detection and provides a rapid and simple estimation of retinol and retinyl palmitate levels using only 180 microliter serum. For these reasons, the HPLC assay is suggested for routine determination of vitamin A in blood.

Adult↗
PubMed1985

Serum lipoproteins protect isolated erythrocytes against retinol-induced haemolysis.

Under physiological conditions no evidence of haemolysis caused by hypervitaminosis A or vitamin A1 therapy was noted so far in the literature. Nevertheless, previous studies have demonstrated that isolated red blood cells were readily lysed by retinol and structurally related compounds [8]. These data are compatible with the existence of serum components with binding-properties comparable to that of retinol-binding protein. We therefore decided to identify additional acceptors for retinol in human serum. It was shown, that serum lipoproteins and to a lesser extent albumin protect red blood cells for the lytic effect of retinol. The amount of lipoproteins, serum, bovine serum albumin and lipoprotein-deficient serum needed to inhibit retinol (9.6 micrograms/ml) by 50% were 3, 58, 325, 1900 micrograms protein/ml respectively. Increasing their concentration in the incubation mixture results in a decrease in the rate of haemoglobin release and at last complete protection was achieved. Altogether, the results suggest that lipoproteins bind retinol and render it therefore non-haemolytic like retinol-binding protein. Furthermore, the latter indicates that lipoproteins act as carriers for vitamin A given parenterally, which one might expect since the lipoproteins are capable of transporting hydrophobic molecules.

Biological Transport↗
PubMed1983

Effects of temperature changes on thymidine kinase in heat- and cold-sensitive cell-cycle mutants and 'wild-type' murine P-815 cells.

Two heat-sensitive (arrested in G1 at 39.5 degrees C) and two cold-sensitive (arrested in G1 at 33 degrees C) clonal cell-cycle mutants that had been isolated from the same clone (K 21), of the murine mastocytoma P-815 cell line, were tested for thymidine kinase (EC 2.7.1.21) activity. After shift of mutant cells to the nonpermissive temperature, thymidine kinase activity decreased, and minimal levels (i.e., less than 3% of those observed for 'wild-type' K 21 cells at the respective temperature) were attained within 16 h in heat-sensitive and after 3-4 days in cold-sensitive mutants, which is in good agreement with kinetics of accumulation of heat-sensitive and cold-sensitive cells in G1 phase. After return of arrested mutant cells to the permissive temperature, thymidine kinase of heat-sensitive cells increased rapidly and in parallel with entry of cells into the S phase. In cultures of cold-sensitive cells, however, initiation of DNA synthesis preceded the increase of thymidine kinase activity by approx. one cell-cycle time. Thymidine kinase activities in revertants of the heat-sensitive and cold-sensitive mutants were similar to those of 'wild-type' cells. In 'wild-type' K 21 cells incubated at 39.5 degrees C, thymidine kinase activity was approx. 30% of that at 33 degrees C. This difference is attributable, at least in part, to a higher rate of inactivation of the enzyme at 39.5 degrees C, as determined in cultures incubated with cycloheximide. The rapid increase of thymidine kinase activity that occurred after shift of K 21 cells and of arrested heat-sensitive mutant cells from 39.5 degrees C to 33 degrees C was inhibited by actinomycin D and cycloheximide.

Animals↗
PubMed1983

Formation of mast cell granules in cell cycle mutants of an undifferentiated mastocytoma line: evidence for two different states of reversible proliferative quiescence.

A heat-sensitive (hs, arrested at 39.5 degrees C, multiplying at 33 degrees C) and a cold-sensitive (cs, arrested at 33 degrees C, multiplying at 39.5 degrees C) cell cycle variant were isolated from an undifferentiated P-815 murine mastocytoma line. At the respective nonpermissive temperature, both the hs and the cs variant cells were reversibly arrested with a DNA content, typical of G1 phase. The cells of two cs variant subclones, when exposed to the nonpermissive temperature of 33 degrees C, formed metachromatically staining granules with an ultrastructure resembling that of mature mast cells. In addition, the cellular 5-hydroxytryptamine content underwent a marked increase, and the cells responded to compound 48/80 by degranulation as described for normal mast cells. On the other hand, in cells of two hs variant subclones, essentially no mast cell granules were detectable at either 33 or 39.5 degrees C. As previously reported, the cs cell cycle variant phenotype is expressed dominantly in heterokaryons obtained by fusing cs with wild-type cells, whereas hs cell cycle variant cells, similar to other hs mutants, were found to behave recessively under these conditions. Thus the state of proliferative quiescence induced in the cs cells at 33 degrees C is qualitatively different from the state of cell cycle arrest observed in hs cells at 39.5 degrees C and may represent a model for proliferative quiescence of differentiated cells in the intact organism.

Animals↗
PubMed1981

Dominant versus recessive behavior of a cold- and a heat-sensitive mammalian cell cycle variant in heterokaryons.

A heat-sensitive (hs, arrested at 39.5 degrees C, termed 21-Ta) and a cold-sensitive (cs, arrested at 33 degrees C, termed 21-Fb) clonal cell cycle variant were isolated from the same clone of the P-815 murine mastocytoma line. At the respective nonpermissive temperatures, both the hs and the cs variant were reversibly arrested in G1 phase, and numbers of cells forming colonies upon reincubation at the permissive temperature remained nearly constant for at least 6 days. Cells arrested in G1 by incubation at the respective nonpermissive temperatures were fused to cells of another P-815 clone (31-S) that had been arrested by serum deprivation. Upon reincubation in medium containing 10% serum for 48 h at 39.5 degrees C, 21-Ta x 31-S heterokaryons, similar to 31-S x 31-S homokaryons, entered the S phase, whereas at 33 degrees C, 21-Fb x 31-S heterokaryons, similar to 21-Fb x 21-Fb homokaryons, remained arrested in G1, indicating a recessive expression of the hs and a dominant expression of the cs phenotype.

Animals↗
PubMed1980

[The course of long-term care with fluphenazine decanoate (Dapotum D)].

After 10 years experience with Dapotum D the statistically elaborated studies of catamnesis deal with 76 patients with more than 5 years permanent adjustment. The objective and subjective tolerance is compared (1) with patients with continuous ambulatory adjustment up to now; (2) patients with continuous in-patient adjustments, and (3) patients who withdrew Dapotum D or changed the medicaments after 5 or more years of permanent adjustment. The study shows a significant stabilization of the clinical picture and a surprisingly good permanent compatibility. This compatibility explains itself by the reduction of objective side effects in comparison with the phase of adjustment; the simultaneous habituation to slight extrapyramidal phenomena effects a very high degree of subjective contentment (90% of the patients). This may be supported by the fact that complete withdrawal of such permanent medication causes, in 36.9% of the patients, late dyskinesias with a tendency to slow remission; the latency of which binds doctor and patient, as indicated, to the successful therapy.

Fluphenazine↗
PubMed1980

[Changes in the long-term psychosis following psychotherapy].

The author compares his own schizophrenic patients treated by him and his co-workers at the Vienna Psychiatric University Clinic between the years of 1949 and 1959 by 'bifocal family therapy', a method developed by him with a control group. In his own patients he has carried out a 20-year follow-up study assessing a subsequent course of their lives. The control group consisted of schizophrenic patients treated in 1970 at the Vienna Psychiatric Hospital along routine lines by pharmacotherapy. The psychotherapy group (n = 116) assessed by social criteria such as work record, partner relationships, children, or social isolation, invalidism at home or in hospital is clearly superior and approaches normality. Yet even they show ongoing signs of dynamic disturbance in the sense described by Janzarik expansive derailment, instability, emptiness) which have statistical relationships with the types of breakdowns in their life history and the kinds of later partner relationships. The author interprets this socially successful psychotherapy as a help in achieving emancipation in relation to a certain situation which arose in its development, but sees in the continued affinity to the basic dynamic disturbance and its influence on partner choice a risk factor of the newly formed family and the issuing children.

Family Therapy↗
PubMed1980

[Chronification of chronic patients from the viewpoint of interaction in the medical treatment system].

Though chronicity in psychiatry seems to have undergone a favorable modification, it has, nevertheless, increased and evolved so to adopte itself to a more liberal society (group techniques having no doubt contributed to this modification). Chronicity is no longer the end result of the asylum and solitude. Stades of chronicity are found in each and every branch of medicine, its development being parallel to the expressive of medicine itself. Due to intensification of preventive medicine and post-cure, chronicity touches not only patients undergoing long-term treatment, but also those attending ambulatories and post-cure institutions, and individuals who are considered ill in their environmental interactions, living recluded lives in order to avoid contact, friction and treatment. Chronification, deriving from the interaction with the therapeutic system, can be avoided if the patient and his milieu, in a common effort, give up the idea of illness and allow confrontation to the aggressive stimuli of society. The lack of understanding on the therapist's side, concerning the above-mentioned effort, in the demonstration that the therapist has a preconceived position in the system. This fact is not surprising since chronification is a target in medicine which defines health as a sort of negative of the illness it treats. On the other hand Freudian psychology should enable us to renounce all absolute idealization and help us seek health conceived as a libidinal blend of Eros and Thanatos. The question is not, therefore, how to avoid chronicity, but how to find a chronicity adapted to the patients biography and not to our own.

Aging↗
PubMed1979

Precursor-product relationships between thymidine nucleotides and DNA in mammalian cells. II. Studies with dTDP and dTTP on cells partially lysed by Brij-58.

Cells from Chinese hamster ovary cell cultures were partially lysed with Brij-58 and incubated in a reaction mixture containing deoxyribonucleoside triphosphates and permitting semiconservative DNA replication. The reaction mixture was supplemented with [3H]dTTP and [14C]dTDP or, alternatively, with [14C]dTTP and [3H]dTDP, and at different times, 3H and 14C specific activities of dTTP and dTDP, as well as 3H/14C ratios in DNA were determined. Isotope ratios in DNA were in good agreement with those expected if dTTP but not dTDP was used as the proximate precursor for DNA synthesis. These data support the conclusion that the thymidine nucleotide used as proximate substrate for DNA replication is dTTP.

Adenosine Diphosphate↗
PubMed1979

Adaptation of thymidine utilization to changing rates of DNA synthesis in the cell cycle.

In synchronous cultures of P-815 murine mastocytoma and of Chinese hamster ovary (CHO) cells, the relative contribution of exogenous thymidine to DNA synthesis was studied by comparing rates of (3H)thymidine incorporation with the rate of DNA synthesis as derived from incorporation of (3H)thymidine (10(-5) M) in the presence of amethopterin. In synchronous P-815 cultures, time-dependent variations of DNA synthesis rates were in close agreement with those of (3H)thymidine incorporation rates at concentrations of the precursor ranging from 5 x 10(-8) to 10(-5) M. Similarly, in synchronous CHO cell cultures prepared by two different methods, time-dependent changes in DNA synthesis rate were almost identical with those of the rate of incorporation of (3H)thymidine supplied at 5 x 10(-8) M. Thus, at a given thymidine concentration in the medium, the proportion of thymine residues in DNA that were derived from exogenous thymidine remained nearly constant, even though rates of cellular DNA synthesis underwent pronounced changes. This indicates that in the synchronous culture systems used, utilization of exogenous thymidine is efficiently adapted to changing rates of DNA synthesis.

Animals↗
PubMed1979

An assay system for factors involved in mammalian DNA replication.

An assay for cellular factors stimulating DNA synthesis by partially lysed CHO cells is presented. The assay is based on the observation that in highly lysed cells, DNA synthesis, as determined by [3H]dTTP incorporation, was only 2-5% of that in gently lysed cells, and that this low level of DNA synthesis could be increased by a factor of approx. 50 by the addition of CHO cell extract (i.e. supernatant of a cell homogenate subjected to high-speed centrifugation). Highly lysed cells were obtained by treatment with 0.1% Brij-58 and 240 mM KCl, while for the preparation of gently lysed cells, 0.01% Brij-58 and 80 mM KCl were used. Incorporation of [3H]dTTP reflected DNA synthesis qualitatively similar to that in intact cells. It was semiconservative, and no repair synthesis was detected unless cells were irradiated with ultraviolet light prior to parital lysis. DNA molecules of 4 S were synthesized and converted to DNA of more than 25 S via 6-12-S intermediates. DNA synthesis was restricted to nuclei from cells in S phase, and cell extract did not induce DNA synthesis in nuclei from cells in G1 phase. Stimulation of DNA synthesis by cell extract was concentration-dependent. Cell extract activity was recovered to more than 50% after (NH4)2SO4 precipitation. Heat-inactivation experiments suggested that cell extract contained at least tow factors timulating DNA replication. This system may, therefore, be used for the purification and characterization of factors participating in DNA replication of mammalian cells.

Animals↗