Biomedical subjects

J Antal

Publications and source records attributed to J Antal.

At least 19 recordsLinked to original sources

PubMed2006

The dose-dependent H2O2 stress response promotes increased survival for Schizosaccharomyces pombe cells expressing HIV-1 Vpr.

Human immunodeficiency virus type 1 (HIV-1) viral protein R (Vpr) exerts multiple effects on viral and host cellular activities during infection, including induction of the cell cycle G2 arrest, and cell death in both human cells and the fission yeast Schizosaccharomyces pombe. We show that treament of exponential-phase wild-type Vpr-expressing S. pombe cells with a low, subinhibitory concentration (0.15 mmol/L) of hydrogen peroxide and 0.1 mmol/L thiamine significantly increased both cell proliferation and survival rates and decreased the number of elongated G2-arrested cells. Short-term, H2O2-induced adaptive stress increased the survival of the cells while acute stress conditions interrupted the Vpr-mediated death of the cells; however, no changes in cell length or cell phase were detected. The results suggest the importance of the oxidative status of the cells in Vpr-mediated processes. Our findings contribute to the development of a new approach via which to investigate the contribution of Vpr to HIV pathogenesis and to reduce the Vpr-mediated effects in HIV-infected patients.

Cell Cycle↗

PubMed2004

Characterization of chromate-sensitive and -tolerant mutants of Schizosaccharomyces pombe.

Stable chromium(VI)-sensitive and -tolerant mutants were obtained by induced mutagenesis of Schizosaccharomyces pombe lysine and leucine auxotrophic heterothallic strains 6chr+ and 9chr+. Eleven of them were selected for further studies. Fast transport of 51CrO4(2-) was detected in a representative sensitive mutant, chr-51S, while the tolerant mutant chr1-66T and the parental strain 6chr+ exhibited significantly lower 51CrO4(2-) uptake. The segregation of tetrads of three selected CrVI-tolerant mutants, chr1-66T, chr1-14T and chr2-04T, strongly indicated that tolerance was determined by single mutations. Random spore analysis proved that the mutations of chr1-66T and chr1-14T were allelic and the mutation of mutant chr2-04T was not allelic with the mutation of chr1-66T. Recombinants carrying the ura4D18 selective marker were created for transformation experiments. Two of them (chr1-661T and chr2-046T) can be used to clone and identify the genes responsible for their CrVI tolerance phenotype.

Alleles↗

PubMed2001

Specificity assay of serine proteinases by reverse-phase high-performance liquid chromatography analysis of competing oligopeptide substrate library.

In this paper we present an HPLC method developed for quick activity and specificity analysis of serine proteinases. The method applies a carefully designed peptide library in which the individual components differ only at the potential cleavage site for enzymes. The library has seven members representing seven different cleavage sites and it offers substrates for both trypsin and chymotrypsin-like enzymes. The individual peptide substrates compete for the proteinase during the enzymatic reaction. The reaction is monitored by RP-HPLC separation of the components. We describe the systematic design of the competitive peptide substrate library and the test of the system with eight different serine proteinases. The specificity profiles of the investigated enzymes as determined by the new method were essentially identical to the ones reported in the literature, verifying the ability of the system to characterize substrate specificity. The tests also demonstrated that the system could detect even subtle specificity differences of two isoforms of an enzyme. In addition to recording qualitative specificity profiles, data provided by the system can be analyzed quantitatively, yielding specificity constant values. This method can be a useful tool for quick analysis of uncharacterized gene products as well as new forms of enzymes generated by protein engineering.

Amino Acid Sequence↗

PubMed1999

Proteinase inhibitors from desert locust, Schistocerca gregaria: engineering of both P(1) and P(1)' residues converts a potent chymotrypsin inhibitor to a potent trypsin inhibitor.

Two peptides, SGCI and SGTI, that inhibited chymotrypsin and trypsin, respectively, were isolated from the haemolymph of Schistocerca gregaria. Their primary structures were found to be identical with SGP-2 and SGP-1, two of a series of peptides isolated from ovaries of the same species (A. Hamdaoui et al., FEBS Lett. 422 (1998) 74-78). All these peptides are composed of 35-36 amino acid residues and contain three homologous disulfide bridges. The residues imparting specificity to SGCI and SGTI were identified as Leu-30 and Arg-29, respectively. The peptides were synthesised by solid-phase peptide synthesis, and the synthetic ones displayed the same inhibition as the natural forms: SGCI is a strong inhibitor of chymotrypsin (K(i) = 6.2 x 10(-12) M), and SGTI is a rather weak inhibitor of trypsin (K(i) = 2.1 x 10(-7) M). The replacement of P(1) then P(1)' residues of SGCI with trypsin-specific residues increased affinity towards trypsin 3600- and 1100-fold, respectively, thus SGCI was converted to a strong trypsin inhibitor (K(i) = 5.0 x 10(-12) M) that retained some inhibitory affinity towards chymotrypsin (K(i) = 3.5 x 10(-8) M). The documented role of both P(1) and P(1)' highlights the importance of S(1)'P(1)' interactions in enzyme-inhibitor complexes.

Amino Acid Sequence↗

PubMed1999

Cloning and functional expression of the cytoplasmic form of rat aminopeptidase P.

A rat cytoplasmic aminopeptidase P was purified from liver cytosol with a procedure including an affinity elution step with 3 microM inositol 1,3,4-trisphosphate. Proteolytic fragments were generated, sequenced and the enzyme was cloned from a rat liver cDNA library. The structure shows high (87.8% and 95.5%, respectively) sequence identity at the nucleotide and amino acid levels with the previously described human putative cytoplasmic aminopeptidase P. The cloned rat enzyme was functionally expressed in Escherichia coli and also in COS-1 cells. Western blot analysis, using an antibody generated against the recombinant protein, and Northern blot hybridization showed ubiquitous expression of the protein in different tissues with the highest expression level in the testis.

Amino Acid Sequence↗

PubMed1996

Alcohol dependence: is carbohydrate-deficient transferrin a marker for alcohol intake?

We investigated %CDT (carbohydrate-deficient transferrin) in 92 ethanol-intoxicated alcohol-dependent patients after consecutive admission to hospital and followed the for 28 days under controlled conditions. At admission, 63% (58 patients) showed elevated CDT (> 2.5%) and 34 patients (37%) had normal CDT levels (< 2.5%). No correlation of the %CDT values to alcohol-related disabilities, severity of the withdrawal syndrome, alcohol-drinking pattern before admission, or several other factors was found. The sensitivity of GGT (gamma-glutamyl transferase) was 58% for the same group of patients. Levels of %CDT decreased during the 28 days following abstinence, whereby we could separate four statistically different groups of "CDT decrease'. In two of these groups, comprising most of the cases studied, normal %CDT levels were reached after 14 days of abstinence. Those patients with %CDT levels exceeding the upper normal level after 14 days of sobriety, showed a decrease during the following 14 days to levels of 2.55-2.61%.

Adult↗

PubMed1996

Carbohydrate-deficient transferrin as a marker of alcohol intake: a study with healthy subjects.

This paper reports the results of a 3-week drinking experiment in 51 healthy male subjects, examining the value of %CDT (carbohydrate-deficient transferrin) in the context of different levels of alcohol intake. All healthy persons were urine-tested drug-free and underwent daily breath alcohol tests for the 7 days preceding, and during the whole 3 weeks of, the experiment. Subjects were divided into five groups, consuming different amounts of alcohol daily over a 3-h period in the presence of the investigators. The five groups consisted of 10, 9, 10, 16 and 6 subjects respectively and consumed a daily dose of ethanol of 20, 40, 60, 80 and 80 g respectively for 3 weeks. No significant changes in %CDT were detected in most subjects, even in the 80 g alcohol-consuming groups. The results suggest that CDT is not sensitive for the detection of short-term heavy drinking by healthy subjects.

Adult↗

PubMed1994

Phase I trial of subcutaneous recombinant macrophage colony-stimulating factor: clinical and immunomodulatory effects.

PURPOSE: Recombinant human macrophage colony-stimulating factor (rM-CSF) has been demonstrated to control the growth, differentiation, and function of mononuclear phagocytes. Preclinical studies have indicated antitumor effects, and therefore a phase I trial of rM-CSF in patients with malignancy was initiated. The toxicity and hematologic and immunologic effects were investigated. PATIENTS AND METHODS: rM-CSF was administered as a subcutaneous injection on days 1 through 5 and 8 through 12. Cycles were repeated every 28 days. Cohorts of four to seven patients received rM-CSF at dose levels from 0.1 to 25.6 mg/m2/d. Forty-two patients received 88 cycles of rM-CSF. All patients had metastatic solid tumors refractory to standard therapy. RESULTS: The toxicity of rM-CSF was mild. Dose-limiting toxicity included thrombocytopenia (two patients) and iritis (one patient) occurring at a dose of 25.6 mg/m2/d. Hematologic studies demonstrated dose-related monocytosis occurring routinely at doses > or = 3.2 mg/m2/d, and thrombocytopenia. Immunologic studies demonstrated enhanced secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1 beta) by monocytes after in vitro stimulation with lipopolysaccharide, and increased expression of TNF-alpha mRNA at higher rM-CSF dose levels. Pharmacokinetic studies demonstrated that the systemic clearance rate of M-CSF increases during week 1 of therapy, resulting in lower blood levels of M-CSF during the second week of therapy. CONCLUSION: rM-CSF can be safely administered to patients, and has biologic activity on peripheral-blood monocytes.

Adult↗

PubMed1992

An EEG analysis of drug effects after mild head injury in mice.

An electroencephalographic (EEG) and behavioral model of head injury in unanesthetized, free moving mice has been used to test the effects of TRH and GM1. In our experimental conditions a mechanical head injury capable of inducing loss of righting reflex for 2 to 60 sec, also induces a consistent decrease of the total power of the spectrum of EEG and a decrease of the power of fast beta band (20-40 Hz) for at least 120 min. TRH, injected after trauma in dose of 10 mg/kg, caused improvement of EEG total power of the spectrum. GM1 in high (30 mg/kg) but not in low dose (5 mg/kg) caused more rapid restoration of both the total power and fast as well as slow beta band power. These results suggest that GM1 has favorable effects on post-concussive neurophysiological symptoms in head injured animals.

Animals↗

PubMed1991

Induction of cytokine messenger RNA and secretion in alveolar macrophages and blood monocytes from patients with lung cancer receiving granulocyte-macrophage colony-stimulating factor therapy.

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) promotes the proliferation and differentiation of hematopoietic progenitor cells. Although preliminary data are available from clinical trials, the effect of GM-CSF on gene expression of immunocompetent cells in treated patients has not been studied. We previously demonstrated that in vitro treatment with GM-CSF also enhances maturation-related anti-tumor activities in mononuclear phagocytes. The purpose of the present study was to examine the effects of in vivo recombinant GM-CSF therapy on alveolar macrophages and blood monocytes, to determine if these cells demonstrated differential expression of cytokine genes, cytokine production, and tumoricidal activity. Alveolar macrophages and blood monocytes were isolated from 13 patients receiving a range of GM-CSF doses (60-250 micrograms/m2/day) by continuous infusion over a 2-week period. Both monocytes and macrophages were isolated prior to therapy and at day 10 of the infusion. Monocytes, in addition, were isolated on day 3 of infusion. Results indicated that GM-CSF therapy enhanced expression of tumor necrosis factor, interleukin 1, and interleukin 6 mRNA in both monocytes and alveolar macrophages. Differential responses, however, were observed in cytokine secretion; monocytes demonstrated enhanced secretion of all three cytokines by day 3 of treatment, but alveolar macrophages showed only enhanced interleukin 6 secretion at day 10. Monocyte tumoricidal activity after in vitro lipopolysaccharide stimulation was also significantly elevated by day 3 of treatment, but at day 10 activity was not statistically different from pretreatment values in either monocytes or alveolar macrophages. These data indicate that GM-CSF exerts striking time-dependent modulatory effects on gene expression and functional activities of monocytes and alveolar macrophages in vivo, although the responses of the two cell types differ with respect to cytokine secretion.

Gene Expression Regulation, Neoplastic↗

PubMed1991

Haemodynamics in the first seconds after coronary artery occlusion.

The changes in cardiac and in total haemodynamics, occurring during the first seconds of occlusion and the subsequent desocclusion of coronary arteries were studied on 28 dogs. The most intensive changes were observed after the trunk occlusion of the left coronary artery. Simultaneously with decreasing blood inflow into the myocardium its contractility and the systolic pressure in the left ventricle and the outflow from the coronary sinus began to fall rapidly. The systolic pressure in the left ventricle decreased within the first 10 s from 24 to 13-15 kPa (180 to 100-110 mm Hg), which means that the systolic pressure fell about 1 kPa (7-8 mm Hg) per second, or 0.5-0.6 kPa (4-5 mm Hg) per systole. At the same time the end-diastolic pressure in the left ventricle also increased from zero to 3-4 kPa (25-30 mm Hg). After the trunk desocclusion of the left coronary artery the systolic pressure in the left ventricle proceeded to fall by about 2-3 kPa (15-22 mm Hg). Only then, 20-25 s after the desocclusion, blood flow in the left coronary artery began to rise intensively and 4-6 s later the myocardial contractility and the systolic pressure in the left ventricle also increased. After unclamping (50-60 s), there was an overshoot of haemodynamic values above preocclusive values and then followed the compensatory phase. This phase lasted 80-90 s and on its peak the pressure and flow parameters increased by about 50-60% above preocclusive values. During the occlusion of ramus interventricularis anterior or ramus circumflexus for 30-60 s the haemodynamic parameters changed only slightly. The same was observed during trunk occlusion of the right coronary artery (30-60 s), but in that case many extrasystoles occurred.

Animals↗

PubMed1987