Biomedical subjects

I Csuka

Publications and source records attributed to I Csuka.

At least 19 recordsLinked to original sources

PubMed2006

The effect of various inflammatory agents on the alternative metabolic pathways of arginine in mouse and rat macrophages.

OBJECTIVE AND DESIGN: The effects of various inflammatory stimuli on the alternative arginine metabolic pathways in mouse and rat peritoneal macrophages were investigated in vitro and compared. TREATMENTS: Mice and rats were injected i. p. with thioglycollate, carrageenan, casein, BCG and Newcastle Disease Virus (NDV) vaccines. METHODS: Peritoneal macrophages were isolated from untreated and treated animals. The activities of nitric oxide synthase (NOS) II and arginase were measured and expressions were followed by Western blotting. The uptake of arginine and nitrite formation of macrophages were also measured. RESULTS: Inflammatory stimuli increased the NO production and the expression and activity of both NOS II and arginase in mice in vitro. On the contrary, the same treatments changed the expression and activity of NOS II only, but not those of arginase in rats. The most marked effects on NO metabolism were produced by casein and NDV treatments. CONCLUSIONS: The activity and expression of NOS II and arginase can be stimulated in peritoneal macrophages in vitro by injecting inflammatory agents into the peritoneal cavity. A markedly different response in arginine metabolism was observed in mouse and rat macrophages. Casein treatment was a potent inducer for both enzymes. NDV vaccines induced mainly NOS II, while thioglycollate induced arginase.

Animals↗

PubMed2000

Effect of cadmium on the relationship between replicative and repair DNA synthesis in synchronized CHO cells.

Repair and replicative DNA synthesis were measured at different stages of the cell cycle in control and cadmium-treated Chinese hamster ovary (CHO-K1) cells. Cells were synchronized by counterflow centrifugal elutriation. Elutriation resulted in five repair and four replication subphases. On Cd treatment, repair synthesis was elevated in certain subphases. Replicative subphases were suppressed by Cd treatment, with some of the peaks almost invisible. The number of spontaneous strand breaks measured by random oligonucleotide primed synthesis assay showed a cell-cycle-dependent fluctuation in control cells and was greatly increased after Cd treatment throughout the S phase. Elevated levels of the oxidative DNA damage product, 8-oxodeoxyguanosine, were observed after Cd treatment, with the highest level in early S phase, which gradually declined as damaged cells progressed through the cell cycle.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2000

Subphases of DNA replication in Drosophila cells.

Exponentially growing Drosophila S2 cells in suspension culture were synchronized at low- and high-resolution centrifugal elutriation, and DNA synthesis was measured by [(3)H]-thymidine incorporation throughout the S phase. At low resolution, one repair peak at the G(1)/G(0) border and two replication peaks known as early and late S subphases were observed. At high resolution, six chronologic compartments were distinguished. The distribution of these peaks indicated one repair peak at 2.05 C value, one minor replication peak at 2.43C, and four major subphases of replication corresponding to 2.64C, 2.89C, 3.32C, and 3.60C, representing 6.7%, 3.4%, 15.3%, 20.4%, 32.1%, and 22.0% of the synthetic activity, respectively. The five major peaks of cell growth with 2.32C, 2.56C, 2.85C, 3.18C, and 3.58C values consistently preceded those of replication subphases.

Animals↗

PubMed1997

Analysis of 5'-termini of early intermediates of Okazaki fragments accumulated in thymocytes after emetine treatment of mice.

Nascent Hg-DNA synthesized by the incorporation of Hg-dCTP in reversibly permeable cells of murine thymocytes has been characterized earlier. Here we describe the analysis of 5' ends of oligonucleotides isolated from thymocytes 48 hr after a single dose of emetine administration to mice. This small-molecular-weight population of nascent DNA shorter than Okazaki fragments was absent in control cells. More than 90% of the terminally 32P-labeled oligonucleotides carried a terminally phosphorylated RNA moiety at the 5' end, as demonstrated by alkaline hydrolysis. The size of the short nascent DNA fragments carrying RNA primers ranged between 9 and 50 nucleotides with an average chain length of 15 nucleotides. These oligomers are regarded as the precursors of the Okazaki fragments.

Animals↗

PubMed1994

Formation of leucyl-leucine-O-methylester in leucine-O-methylester treated cells.

Porcine polymorphonuclear cells (PMN) and murine macrophages (M phi) were treated in vitro with Leu-OMe or Leu-Leu-OMe (1.5-5.0 mM) for various periods of time. It was found that the Leu-OMe and Leu-Leu-OMe entered cells rapidly, concomitantly the intracellular leucine accumulated. The methyl derivative diffused faster than Leucine due to its lipophylic character. The Leucine-O-methylesters hydrolysed rapidly as a consequence of the esterase and peptidase activities. The cells treated with Leu-OMe accumulated a high amount of Leucine and some Leu-Leu-OMe too. It was found that the formation of the didpeptide-methylester is not a spontaneous process, rather an enzymatic one. The Leu-OMe treated cells serve as a model which can be used to investigate the effect of the amino acid metabolism and the formation of dipeptides intracellularly and extracellularly.

Animals↗

PubMed1993

Oncogene expression in thymocytes after emetine treatment of mice.

Emetine (33 mg/kg IP) was used as an immunosuppressive agent to inhibit thymic development. The specific and reversible effect of emetine on the macromolecular biosynthesis of thymocytes provided an in vivo model to investigate cellular differentiation. Cortical cells emigrated upon emetine administration at the early stage of inhibition of macromolecular synthesis, followed by a repopulation stage and differentiation of the thymus. Early events of differentiation were measured by the gene expression of oncogenes showing a gradual decrease of c-myc mRNA level, a temporary decline in c-fos mRNA which was reversed at t = 72 h after emetine treatment. The two-fold increase in mRNA synthesis of c-src oncogene after emetine treatment was paralleled by a fivefold rise in total tyrosine kinase activity. The concomitant appearance of an M(r) = 60,000 protein a t = 96 h after emetine treatment may be an indication of the involvement of specific proteins in thymic development.

Animals↗

PubMed1993

In vitro effect of leucine-O-methylester on polymorphonuclear and mononuclear cells.

The uptake of Leu-OMe and Leu-Leu-OMe was studied in vitro in porcine PMN cells. Both methylesters are metabolized leading to the intracellular accumulation of leucine. Part of the hydrolyzed leucine gradually filtrates back into the culture medium in a time-, temperature- and methylester substrate concentration-dependent manner. Another portion of Leu-OMe is converted to Leu-Leu dipeptide. With respect to the cellular effects of Leu-OMe treatment ultrastructural studies showed the presence of large vacuoles without significant alteration of cell viability. Increased exocytosis of lysosomal enzymes did not lead to lytic events. Changes in the plasma membrane are indicated by the observation that Leu-OMe treatment causes the loss of the chemotactic activity to formyl-Met-Leu-Phe.

Animals↗

PubMed1993

Evidence for the pre-synthesized state of secreted macrophage arginase: arginase activity cannot be modified in short-term cultures.

The arginase produced by peritoneal macrophages is not synthesized de novo in short-term (3 h) cultures after harvesting the cells. In long-term cultures the arginase synthesis is restored. In contrast to arginase lysozyme is continuously synthesized in short-term cultures. These statements were proved by the following experimental results: 1. Protein synthesis inhibitor and lysosomotropic agents did not alter the arginase level. 2. Arginine and its analogue, canavanine and ornithine were not able to change the arginase activity. 3. The product of an alternative metabolic pathway of arginine, sodium nitrite, did not affect arginase activity. 4. Effectors influencing the synthesis of cyclic nucleotides (cAMP, cGMP), indomethacin, sodium nitroprusside and an analogue of cAMP had no effect on the arginase activity. 5. Arginase activity could not be significantly modified either by an in vitro Micrococcus luteus treatment or by changing the adherence period of peritoneal exudate cells. 6. When arginase was produced in murine peritoneal macrophages at various periods with medium change, the total arginase released into the media from murine and rat macrophages did not exceed the original intracellular arginase content of the adhered cells during the first 6 hours.

Animals↗

PubMed1992

[The effect of low density lipoprotein (LDL) on NO formation and on arginase activity in mouse peritoneal macrophages].

A large body of the evidence is available to the causative relationship between the elevated blood plasma concentrations of LDL and the atherogenesis. The oxid-LDL (modified LDL) is internalized more rapidly by the macrophages, and there is now substantial evidence that the modified LDL is actually present in atherosclerotic lesions. Recently it has been proved that the endothel cells and monocyta/macrophages generate nitric oxide (NO) from arginine, and that the LDL inhibits the formation of NO in endothel cells. The authors found that the human LDL in vitro exerts an inhibitory effect on the formation of NO in murine PED (peritoneal exudate cells) and synchronously severalfold increasing of the arginase activity in the culture media. Both effects of LDL proved to be dose dependent and the oxid-LDL has been found to be more effective. The increased activity of arginase provides a very likely explanation for the reducing of NO production in macrophage treated by LDL. The reducing or blocking of NO-formation causes a local vasocontraction which induces clinical symptoms.

Animals↗

PubMed1992

[The role of endogenous free radicals of nitric oxide (NO)].

The role of endothelium in vasodilatation has only emerged in the last ten years. It was observed that many endogenous substances from endothelial cells triggered the release of a substance which was named endothelium-derived relaxing factor (EDRF). Later has been showed that NO accounted for most if not all of the biological activity of EDRF. The endothelial synthesis of NO originates from L-arginine and could be blocked by the methyl analogue (e.g. NG-mono-methyl-L-arginine). Beside endothelial cells NO could be identified in several mammalian tissues including brain, hepatocytes, lung and macrophages. NO mediated the control of vascular tone and blood pressure via vascular smooth muscle cells which exert relaxation and constriction of blood vessels. It is considered NO represents signal for the guanylate cyclase system which regulates the intracellular concentration of Ca2+ ions. It is well known that the concentration of Ca2+ ions play discern direct role in the relaxation and contraction of smooth muscle, respectively.

Endothelium↗

PubMed1992

Inverse relation in the de novo arginase synthesis and nitric oxide production in murine and rat peritoneal macrophages in long-term cultures in vitro.

1. The de novo synthesis of arginase was much higher in murine than in rat peritoneal macrophages. This process was inhibited irreversibly by protein synthesis inhibitors and reversibly by glycolysis blockers. 2. Rat macrophages produce more nitric oxide (NO) than murine cells. NO production was inhibited by the inhibitors of protein synthesis or glycolysis. 3. The loading of macrophages by exogenous arginine for 24 hr in vitro resulted in the increase of arginase and nitrite in macrophages to different extents. 4. No great differences in lysozyme production was observed. 5. The proportion of arginine taken up and incorporated is contrasted in murine and rat macrophages.

Amino Acids↗

PubMed1992

Differences and similarities in the sensitivity of lymphocytic and macrophage plasma membrane to deoxycholate.

Human tonsillar lymphocytes separated on nylon wool and rat macrophages showed different sensitivity to deoxycholate (DOC) treatment at a low (0.24 mM, 0.01%) concentration for 3 h. The T cell-enriched fraction was stimulated more readily by PHA whereas the B-cell enriched fraction lost its adherence and a decrease of chromium binding capacity was observed after the detergent treatment. Rat peritoneal macrophages under the same conditions lost their chromium label and lysozyme content, whereas their adherence and phagocytic capacity decreased dramatically without affecting their binding capacity. Higher sensitivity to the detergent was observed in peritoneal macrophages compared to tonsillar lymphocytes when various DOC concentrations were used. These findings proved that this low concentration DOC treatment, at least in macrophages, touched mainly the adhesive proteins and the dynamics of the membrane and not its receptor-associated properties.

Animals↗

PubMed1991

Differences in the arginase activity produced by resident and stimulated murine and rat peritoneal macrophages.

1. Murine macrophages showed a considerably higher in vitro arginase production in short time cultures than rat peritoneal cells. 2. The in vivo stimulation with casein or thioglycollate resulted in an enhanced in vitro enzyme production in mice. 3. The adherence is not the condition of the enzyme production. 4. The difference between the two species cannot be explained by the lack of bivalent ions, the absence of energy supply, proteolysis, the low number of macrophages or by the different cell types of the peritoneal exudate of mouse and rat. 5. The lysozyme production of murine and rat peritoneal macrophages was also investigated and no difference was observed between the two species.

Animals↗

PubMed1991

Morphological studies on the effect of L-leucine methyl ester on mouse peritoneal macrophages in vitro.

Mouse peritoneal macrophages (MO) were treated in culture with 5 mM L-leucine methyl ester (L-Leu-OMe), for 5, 10, 20, 40, and 60 min. The treatment resulted in rapid vacuolisation of the cytoplasm due to the dilatation and disruption of lysosomes. Autophagy caused by lysosomal enzymes destroyed most of the cytoplasmic organelles by 40 minutes after L-Leu-OMe treatment, but the cell membrane and nucleus were in many MOs resistant to the damage. 60 min after L-Leu-OMe treatment most of the MOs were killed. It is supposed that the disruption of the lysosomes is caused by formaldehyde produced by the hydrolysis of L-Leu-OMe.

Animals↗

PubMed1990

Effect of emetine on the plasma cell population of chicken's gland of Harder.

The emetine effectively abolished the plasma cell population in the chicken's gland of Harder by day 3 of treatment. The plasma cell content regenerated by day 5 following emetine injection, possibly from a metabolically inactive, resting B cell population which was resistant to the emetine treatment. By day 7 extracellular substance in a very large quantity appeared among the plasma cells and epithelial cells which might represent a hyperactive plasma cell secretion. The changes in the circulating antibodies measured by hemagglutination well-correlated with the plasma cell content in the gland of Harder. The gland of Harder (GH) is an accessory lacrimal gland. Its main function is to lubricate the nictitating membrane and keep the surface of the eyeball wet. The presence and regulatory function of cAMP dependent histone kinase was showed. Since it has been published that in chicken the interstitium of this gland contains a proper amount of plasma cells, this observation called the attention of many investigators to study the role of GH in the immune response. The B cell maturation in the chicken GH has been studied. The surface marker studies have proved that beside the B cells the gland contains functionally adequate number of T cell which exert stimulatory effect on B cells to promote their transformation to plasma cells. In addition to T and B cells small number of macrophages also occur. In the 9 H the number of plasma cells is age dependent. At hatch only a few plasma cells occur in the interstitium of the gland but by 3 weeks of age they become predominant. Different isotypes of immunoglobulins are secreted by these plasma cells.

Animals↗

PubMed1989

The effect of L-leucine methyl ester on the phagocytosis and amino acid incorporation of murine peritoneal cells.

Murine peritoneal macrophages were treated in vitro with L-leucine methyl ester (0.25-5.0 mM). This treatment resulted in an inhibition of the amino acid incorporation into the cells both at 4 degrees C and 37 degrees C during a relatively short incubation period. The adherence of macrophages was not changed by the treatment. Bacterial phagocytosis was partly influenced: Leu-OMe did not change the binding but the engulfment of opsonized bacteria was blocked. Damage of the plasma membrane caused by Leu-OMe was not so serious as that produced by specific anti-PEC antiserum. Leu-OMe is a lysosomotropic agent accumulated preferentially by lysosomes. The vacuolization of the cells and the dilatation of the vacuoles are evidences for the intracellular damage. In the early phase this damage is characterized only by the leakage of the cytoplasm, later the damage of the plasma membrane can also be demonstrated.

Animals↗

PubMed1988

Structural changes in the mouse thymus and lymph node after emetine treatment.

The effect of emetine which is a potent immunosuppresant was studied on the thymus and lymph node. The subcapsular zone of the thymus was depleted and large number of adherent cells accumulated in this thymic region. The medulla enlarged but the cortico-medullary border remained distinct. In the paracortex (T dependent area) of the lymph node many non-lymphoid pyroninophil cells appeared which is followed by an increased cell proliferation 24 hours after emetine injection. 48-60 hours after administration many macrophage-like cells appeared in the medullary sinuses. This macrophage invasion precedes the adherent cell accumulation in the subcapsular zone of the thymus suggesting a possible non-lymphoid (adherent) cell migration from the lymph node's paracortex to the thymus.

Animals↗

PubMed1987

Cytostatic peptide isolation from culture media of mouse peritoneal exudate cells.

It was found that the supernatant of mouse PEC culture medium (MCM) (both resident and casein-elicited cells) has an inhibitory effect in vitro on the incorporation of [3H]TdR into DNA of mouse spleen cells. The inhibitory effect in the MCM appears in the first 24 hr and also reaches its maximum value within this time. The inhibitory effect of this factor could not be demonstrated in the extract of freshly harvested M phi cells. The factors responsible for inhibition proved to be heat stable at 80 degrees C for longer than 30 min. Following heat treatment, the crude extract was separated into four fractions absorbing uv light at 280 nm using Sephadex G-25 column chromatography, and the most potent biologically active inhibitory factor was eluted in the last fraction. This fraction could also be obtained with a more effective permeation volume using Trysacryl GF 05 gel chromatography, and the active B fraction from this chromatography could be separated into four subfractions by isotachophoresis (ITP). The active fraction, which was obtained by Trysacryl GF 05 gel chromatography and further separated by ITP, was found to be highly inhibitory. It contained a peptide-like substance with a molecular mass of approximately 2.0 kDa and had an anionic character at pH 4.0. The inhibitory effect of MCM cannot be influenced either by inhibitory compounds of protein synthesis or by proteolysis blocking agents. Furthermore, the inhibitory effect is shown to be reversible and is more pronounced on B cells than on T lymphocytes.

Animals↗