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Biomedical subjects

J Szopa

Publications and source records attributed to J Szopa.

At least 37 records · Page 2Linked to original sources
PubMed1993

Is an increase of deoxyribonucleases activity in uraemic lymphocytes caused by their augmented synthesis in these cells?

Deoxyribonucleases activity in T and B lymphocytes isolated from 45 patients with chronic renal failure and 30 control subjects was measured. The results obtained clearly show a dramatic increase in enzyme activity in both T and B lymphocyte cells isolated from uraemic patients when compared with the control cell. The increase in enzyme activity was limited to the group of relatively small nucleases ranging from 14 kDa to 18 kDa. Since it was shown previously that these nucleases are among the cleavage products of the largest subunit of DNA-dependent RNA polymerase class I, it is suggested that a characteristic feature of the lymphocyte cell isolated from uraemic patients is increase of RNA polymerase lability, thus resulting in RNA synthesis decrease. Amongst toxins increasing catabolism of the active polymerase enzyme, a significant correlation with the vise of lymphocyte Mg2+ and Mn2+ ions was disclosed.

Adult↗
PubMed1993

DNA-dependent RNA polymerase enzymes affected in uraemic lymphocyte cells.

The DNA-dependent RNA polymerase activity and endonucleases in uraemic lymphocyte cells were investigated. It was found that the activity and quantity in three classes of polymerases are remarkably reduced. The reduction in enzyme activity is accompanied by increasing endonuclease activity. The relationship of polymerase enzymes with endonucleases is discussed.

Adult↗
PubMed1993

Uraemic lymphocytes: analysis of their nuclease activity.

The nuclease activity in T and B lymphocytes isolated from patients with chronic renal failure and control subjects was studied. The data obtained show a slight increase in nuclease activity in T and B cells isolated from uraemic patients as compared to the control cells. The increase in enzyme activity was limited to the group of relatively small nucleases with molecular weights ranging from 14 kDa to 18 kDa. It was documented previously that these nucleases are among the cleavage products of the largest subunit of DNA-dependent RNA polymerase I, which is responsible for ribosomal RNA synthesis. Thus, we suggest that the characteristic feature of lymphocytes isolated from uraemic patients is lowering of their metabolic activity. Amongst toxins increasing catabolism of the active enzyme, a significant correlation with the rise of lymphocyte Mg2+ and Mn2+ ions was disclosed.

Adult↗
PubMed1993

Increase in deoxyribonuclease activity in uraemic lymphocytes is caused by the cleavage of the largest polymerase I subunit.

Deoxyribonucleases and DNA-dependent RNA polymerase activities in T and B lymphocytes isolated from patients with chronic renal failure and control subjects were studied. The data clearly shows that the nuclease activity in T and B cells isolated from uraemic patients is remarkably enhanced when compared to the control cells. Concomitant with the enhancement in enzyme activity, the reduction in RNA polymerase I activity and quantity was observed. It was found that the increase in nuclease activity and quantity was limited to the group of relatively small nucleases with molecular weights ranging from 14 kDa to 18 kDa. It has been reported previously that these nucleases are among the cleavage products of the largest subunit of DNA-dependent RNA polymerase I. Thus we suggest that the depressed metabolic activity is a characteristic feature of the uraemic lymphocyte cells and the observed increased in DNase activity in those cells is a result of polymerase I degradation.

Adult↗
PubMed1992

Deoxyribonuclease activity in T and B lymphocytes of haemodialysed patients with uraemia.

Deoxyribonuclease (DNase) activity and metal ion concentrations in lymphocytes of patients with chronic renal failure and in healthy controls were studied. The data suggest that T and B lymphocyte nuclei of patients with renal failure show increased DNase activity when compared to their healthy counterparts. It is suggested that the enhancement of enzyme activity is a result of increased metal ion concentration rather than increased enzyme copy count. The data strongly suggest that haemodialysis of uraemic patients is more effective for improvement of lymphocyte metabolism than the conservative chemical treatment.

Adult↗
PubMed1991

Deoxyribonuclease activity in lymphocytes of patients with chronic renal failure treated conservatively.

The activity of nucleases and concentrations of highly important metal ions in T and B lymphocytes were examined. The source of lymphocyte was the blood of patients with chronic renal failure and activity of enzyme as well as ion concentrations were compared to the control group. Concomitant with the increase in enzyme activity was an increase of metal ion concentrations assayed in both T and B lymphocytes isolated from patients with renal disease. The data suggest that the enhancement of nuclease activity is a result of increased enzyme polypeptide synthesis and its stimulation by metal ions. Utilization of the nuclease test for monitoring uraemic toxicity is considered.

Adult↗
PubMed1991

[Metabolic differentiation of peripheral blood lymphocytes after kidney transplantation in relation to post-transplantation immuno- suppression in the light of the analysis of cellular activity of DNA transcription enzymes].

The activity of three classes DNA-dependent RNA polymerases in T and B lymphocyte cells nuclei isolated from peripheral blood of patients with transplanted kidney were investigated. Twenty three patients with transplanted organ in age 35 +/- 9.7 treated simultaneously with cyclosporin A and small doses of prednisone and thirteen persons after renal transplantation in age 34.8 +/- 6.3 treated conservatively (azathioprine plus prednisone) were studied. The enzymes activity was assayed by the measurement of [3H] UTP incorporated into acid insoluble product in the presence of alpha-amanitin when specified. Both, "bound" and "free" enzymes activity was analysed. "Bound" polymerase is defined by the ability to transcribe endogenous template in the absence of exogenous DNA. "Free" enzyme was determined by the additional transcription on exogenous, calf thymus DNA as template. The quantity of polymerase I subunits by Western blotting was also analysed. It was shown that the polymerizing enzymes activity strongly depend upon haemodialysis period of time prior to organ transplantation as well as upon the treatment after transplantation. Characteristically in case of T lymphocyte isolated from patients treated with cyclosporin A, the transplant rejection process was accompanied by large increasing in polymerase activity especially in polymerase I. The correlation in polymerase activity and transplant rejection time was clearly observed. In case of lymphocyte cells isolated from patients with renal transplant treated conservatively, the polymerase activity in both T and B cell was slightly reduced. The useful of polymerase assay for monitoring of patients with renal transplant is considered.

Adult↗
PubMed1991

[Analysis of the activity of matrix DNA synthesis in the lymphocytes of patients after kidney transplantation and the role of the processes of degradation of DNA-dependent RNA polymerases in the overall cellular nucleolytic activity].

The activity and quantity of deoxyribonucleases in T and B lymphocyte cells isolated from peripheral blood of patients with transplanted kidney were investigated. Twenty three patients with transplanted organ, aged 35 +/- 9.7, treated with cyclosporin A and thirteen individuals after renal transplantation in age 34.8 +/- 6.3 treated conservatively were studied. The enzyme activity was defined as resting DNase activity (DNase 0). Where specifiel the reaction mixture was supplied either with 5 mM MgCl2 (DNaseMg2+) or 1 mM MnCl2 (DNase1 x Mn2+) or 2 mM MnCl2 (DNase2 x Mn2+). Two enzyme groups with molecular mass 32 kDa and 14 to 18 kDa were analyzed. It was evidenced that the nuclease activity in B lymphocyte isolated from patients treated with cyclosporin A after organ transplantation was quite close to the control subjects. On the contrary, the nucleases activity and quantity increased in T lymphocyte of the same patients and increasing in enzymes activity was depending upon haemodialysis period of time prior to organ transplantation. Enzymes activity correlate with clinical parameters typical for kidney transplant rejection. The activity and quantity of nucleases was slightly reduced in both T and B lymphocytes isolated from patients treated conservatively after organ transplantation. The useful of nuclease assay for monitoring of kidney transplant rejection is discussed.

Adult↗
PubMed1988

Association of DNA topoisomerase I and RNA polymerase I: a possible role for topoisomerase I in ribosomal gene transcription.

RNA polymerase I preparations purified from a rat hepatoma contained DNA topoisomerase activity. The DNA topoisomerase associated with the polymerase had an Mr of 110,000, required Mg2+ but not ATP, and was recognized by anti-topoisomerase I antibodies. When added to RNA polymerase I preparations containing topoisomerase activity, anti-topoisomerase I antibodies were able to inhibit the DNA relaxing activity of the preparation as well as RNA synthesis in vitro. RNA polymerase II prepared by analogous procedures did not contain topoisomerase activity and was not recognized by the antibodies. The topoisomerase I: polymerase I complex was reversibly dissociated by column chromatography on Sephacryl S200 in the presence of 0.25 M (NH4)2SO4. Topoisomerase I was immunolocalized in the transcriptionally active ribosomal gene complex containing RNA polymerase I in situ. These data indicate that topoisomerase I and RNA polymerase I are tightly complexed both in vivo and in vitro, and suggest a role for DNA topoisomerase I in the transcription of ribosomal genes.

Animals↗
PubMed1988

Proteolysis of spectrin by trypsin and pronase in the presence of phospholipid suspensions.

The effect of phospholipid suspensions on the proteolysis of isolated spectrin was examined by SDS-polyacrylamide gradient gel electrophoresis. Proteolysis of spectrin in the membranes by trypsin and pronase was also studied. It was found that electrophoretic patterns of spectrin fragments were influenced by the presence of the suspension prepared from phosphatidylethanolamine:phosphatidylserine (60:40) mixture and of phosphatidylcholine. Qualitative changes in the proteolytic patterns obtained after proteolysis of spectrin by pronase in the presence of phosphatidylcholine suspension were observed. The changes in the sensitivity of spectrin towards proteases result probably from changes in the accessibility of some peptide bonds upon the interaction of this extrinsic protein with phospholipids.

Animals↗
PubMed1986

Cleavage of the 190-kDa subunit of DNA-dependent RNA polymerase I yields small polypeptides capable of degrading DNA.

The lability of RNA polymerase I has been examined by incubation at 37 degrees C. Under the conditions used virtually all enzyme activity was lost after 90 min incubation at this temperature. Concomitant with the decrease in enzyme activity was the disappearance of the 190-kDa enzyme subunit and the production of three small polypeptides of Mr 14,000-19,000. Using immunological methods the small polypeptides were shown to be cleavage products of the 190-kDa subunit. The 190-kDa-derived polypeptides retained all the antibody-binding sites of the large subunit that are important in RNA synthesis. The isolated cleavage products were able to bind to DNA as well as to active enzyme and to inhibit reversibly RNA synthesis. In addition to their binding properties, the 190-kDa-derived polypeptides, but not the intact 190-kDa subunit, were able to degrade DNA. These data suggest that multiple mechanisms exist in the control of RNA polymerase I-catalyzed transcription, namely, irreversible loss of the catalytic subunit coupled with reversible inhibition by the cleavage products as a result of competition for normal enzyme-DNA interactions and, possibly, involving activation of a cryptic nuclease.

Animals↗
PubMed1980

Influence of histone phosphorylation upon histone-histone interactions studied in vitro.

Histones H2b and H3, phosphorylated in vitro with the catalytic subunit of protein kinase I from rabbit skeletal muscle, were used to estimate the influence of histone phosphorylation upon histone-histone complex formation. Stoichiometry and interaction affinity of the complexes H2a-H2b, H4-H2b, and H4-H3 were determined by using the continuous variation method based on circular dichorism or fluorescence intensity. All complexes exhibit a 1:1 stoichiometry in sodium phosphate or sodium chloride solution of pH 7.0. The association constants of the complexes containing phosphorylated H2b were only slightly reduced, whereas that with phosphorylated H3 was strongly reduced relative to those of the nonphosphorylated species.

Animals↗
PubMed1980

Purification and properties of a DNase inhibitor from Nicotiana tabacum cell cultures.

Extraction of Nicotiana tabacum cell cultures, chromatography on DEAE-cellulose and gel filtration resulted in a homogeneous protein (Mr = 14500), which strongly reduces the hydrolysis of Escherichia coli DNA by DNase I. DNA degradation by micrococcal nuclease is not inhibited. The inhibitor protein interacts with DNase I in the absence of DNA, as determined by the partial quenching of protein intrinsic fluorescence; a 1:1 stoichiometry is deduced. From the reduction of DNase I activity with increasing inhibitor concentration apparent equilibrium constants for the inhibitor X DNase-I complex have been calculated. This interaction is strongly temperature-dependent; at 20 degrees C and 26 degrees C dissociation constants of 5 nM and 110 nM, respectively, were determined. As a consequence a rather high enthalpy of interaction can be estimated.

Cells, Cultured↗
PubMed1980

The kinetics of the interaction of a helix-destabilizing protein from roe-deer liver with DNA and the influence of phosphorylation.

The kinetics of the interaction of the DNA double-helix-destabilizing protein from roe-deer liver with different DNAs revealed a fast phase which is observed both by the increase in A260 of the DNA and the quenching of the protein intrinsic fluorescence. A slow phase with a smaller amplitude is only recorded by the increase of A260.--The protein contains slightly less than two phosphate groups per molecule, removal of one of which by alkaline phosphatase does not affect its activity; however, removal of both phosphates decreases the DNA-unwinding property significantly. A similar decrease in activity is also revealed upon incorporation of an additional phosphate by cAMP-dependent protein kinase I.--Results of the protection of poly[d(A--T)] from DNase I digestion by the protein are in favor of a migration of the protein along the DNA.

Animals↗