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Biomedical subjects

E Kiss

Publications and source records attributed to E Kiss.

At least 55 records · Page 3Linked to original sources
PubMed2000

Ternary complex formation between VO(IV)-picolinic acid or VO(IV)-6-methylpicolinic acid and small blood serum bioligands.

In order to assess the role of the low molecular mass bioligands of blood serum in vanadium binding, a study was made of the interactions of the complexes formed in the VO(IV)-picolinic acid and VO(IV)-6-methylpicolinic acid systems with various low molecular mass constituents of blood serum, such as oxalate, lactate, citrate and phosphate. The speciation of VO(IV) in these ternary systems and also in the binary VO(IV)-picolinic acid and VO(IV)-6-methylpicolinic acid systems was studied by pH-potentiometry at 25 degrees C and at an ionic strength I = 0.2 M (KCl). The binding modes of the complexes formed were determined by spectral (electronic absorption and EPR) methods. Picolinic acid and 6-methylpicolinic acid were found to form mono and bis complexes through the pyridine nitrogen and carboxylate oxygen, but the presence of the methyl group in 6-methylpicolinic acid surprisingly decreases the stability of its complexes significantly. The results obtained on the ternary systems reveal that mixed ligand complex formation is favoured in these systems, especially with citrate, and must therefore be taken into account in the speciation description of VO(IV) in blood serum.

Citric Acid↗
PubMed2000

Study of the subunit interactions in myosin phosphatase by surface plasmon resonance.

The interactions of the catalytic subunit of type 1 protein phosphatase (PP1c) and the N-terminal half (residues 1-511) of myosin phosphatase target subunit 1 (MYPT1) were studied. Biotinylated MYPT1 derivatives were immobilized on streptavidin-biosensor chips, and binding parameters with PP1c were determined by surface plasmon resonance (SPR). The affinity of binding of PP1c was: MYPT11-296 > MYPT11-38 > MYPT123-38. No binding was detected with MYPT11-34, suggesting a critical role for residues 35-38, i.e. the PP1c binding motif. Binding of residues 1-22 was inferred from: a higher affinity binding to PP1c for MYPT11-38 compared to MYPT123-38, as deduced from SPR kinetic data and ligand competition assays; and an activation of the myosin light chain phosphatase activity of PP1c by MYPT11-38, but not by MYPT123-38. Residues 40-296 (ankyrin repeats) in MYPT11-296 inhibited the phosphorylase phosphatase activity of PP1c (IC50 = 0.2 nM), whereas MYPT11-38, MYPT123-38 or MYPT11-34 were without effect. MYPT140-511, which alone did not bind to PP1c, showed facilitated binding to the complexes of PP1c-MYPT11-38 and PP1c-MYPT123-38. The inhibitory effect of MYPT140-511 on the phosphorylase phosphatase activity of PP1c also was increased in the presence of MYPT11-38. The binding of MYPT1304-511 to complexes of PP1c and MYPT11-38, or MYPT11-296, was detected by SPR. These results suggest that within the N-terminal half of MYPT1 there are at least four binding sites for PP1c. The essential interaction is with the PP1c-binding motif and the other interactions are facilitated in an ordered and cooperative manner.

Amino Acid Sequence↗
PubMed2000

Hypercoagulability in various autoimmune diseases: no association with factor V Leiden mutation.

The coagulation factor V Leiden mutation, leading to resistance to activated protein C (APC), is the most common inherited risk factor for venous thrombosis. In various systemic autoimmune diseases the hypercoagulable state was shown to be associated with the presence of antiphospholipid antibodies (aPL). Our aim was to determine the prevalence of both, Leiden mutation and aPL in autoimmune diseases and their impact on the occurrence of venous thrombosis. The dataset consists of results from 137 patients having Sjögren's syndrome (n = 50), progressive systemic sclerosis (n = 43) (PSS), undifferentiated connective tissue disease (n = 24) (UCTD) and mixed connective tissue disease (n = 20) (MCTD) with or without venous thromboembolic complications. The Leiden mutation was detected with polymerase chain reaction (PCR), aPL, such as lupus anticoagulant (LA) with screening and confirmatory procedures and others with enzyme linked immunosorbent assay (ELISA). The prevalence of mutation ranged between 8.3% and 18.0% (13.1%). The thromboembolic risk was found to be increased in the presence of aPL. Eight patients (5.84%) (4 heterozygous) experienced thromboembolic events and 3 out of 4 heterozygous showed aPL positivity, too. There were no difference between the frequencies of Leiden mutation in examined systemic autoimmune diseases and unselected populations.

Activated Protein C Resistance↗
PubMed2000

Usefulness of detection of complement activation products in evaluating SLE activity.

Complement activation products, such as C1rs-C1inh, specific for the activation of the classical pathway, C3b(Bb)P, specific for the activation of the alternative pathway and SC5b-9, specific for common terminal pathway of the complement cascade, were measured in healthy donors and in patients with clinically active and inactive systemic lupus erythematosus (SLE). Plasma levels of C3b(Bb)P and SC5b-9 were moderately, those of C1rs-C1inhibitor (C1rs-C1inh) were markedly elevated in patients with clinically inactive SLE, compared with healthy controls. The difference between active and inactive stages of the disease was best reflected by C3b(Bb)P plasma concentration (P<0.001), which also showed the highest correlation with the SLEDAI (Rs=0.41 P<0.001) and which was the most useful in distinguishing active and inactive sample pairs as well. The difference between SC5b-9 levels in the active and inactive stages was also significant (P=0.007), while that of C1rs-C1inh did not differ significantly (P=0.136). The correlation of the SLEDAI with SC5b-9 was 0.3 (P=0.015), while with C1rs-C1inh it was 0.21 (P=0. 089). These findings suggest that the measurement of complement activation products, especially that of the alternative pathway, are sensitive markers of the activity of SLE and can be used for clinical purposes.

Adult↗
PubMed2000

The Leiden mutation of coagulation factor V in Hungarian SLE patients.

We studied the prevalence and the effect of coagulation factor V Leiden mutation on the occurrence of thrombotic episodes in 120 Hungarian patients having systemic lupus erythematosus (SLE) with or without antiphospholipid antibody. The frequency of the factor V Leiden mutation in Hungarian SLE patients was 13%, which is comparable with those found previously in a healthy Caucasian population. The incidence of venous thrombosis among factor V Leiden carriers has been found to be higher (odds ratio [OR] 1.7) than it is in patients without Leiden mutation (38% vs 29%). In addition, the frequency of venous thrombosis in the heterozygous SLE patients (OR 8.4 [confidence interval (CI) 0.8-83.9] P = 0.06) is dependent on the coexistence of other risk factors, such as antiphospholipid antibody. Moreover, among heterozygous factor V SLE patients, the Leiden mutation could explain the tendency to have significantly higher prevalence of fetal losses (OR 3.9 [CI 1.2-12.0] P = 0.02) and higher prevalence of cerebrovascular lesions, cardiac valvular abnormalities, and Raynaud's syndrome than that found in individuals without factor V Leiden mutation of those having antiphospholipid antibody. Systemic lupus erythematosus patients with combined defects suffer more severely from thrombosis than those with a single risk factor do, suggesting that thrombophilia is a multifactorial disorder in SLE, also. Although, the factor V Leiden mutation does not seem to be a significant risk factor for venous thrombosis in SLE, these data demonstrate that Leiden mutation can be regarded as an additive thrombogenic factor providing higher predisposition to several vasoocclusive disorders in SLE.

Abortion, Spontaneous↗
PubMed2000

Myelofibrosis in systemic lupus erythematosus.

In this study we present a case of coexisting systemic lupus erythematosus (SLE) and myelofibrosis. Literature review supports the fact that the two diseases rarely occur together in the same patient. The young female patient studied was admitted with pancytopenia and a clinical picture which met the criteria of SLE. Histological examination of the bone marrow biopsy revealed severe myelofibrosis with hypocellularity of the myeloid cell lines. Treatment with immunosuppressive and colony stimulating factor led to slow but complete regeneration of the bone marrow and subsequently to an improved haematological status, and the patient was spared bone marrow transplantation.

Adolescent↗
PubMed2000

Antiprothrombin and antiannexin V antibodies imply risk of thrombosis in patients with systemic autoimmune diseases.

OBJECTIVE: To investigate the relationship between antiprothrombin (aPT) and antiannexin V (aANX) autoantibodies of IgG isotype and thrombosis in patients with systemic autoimmune diseases. To compare the clinical relevance of these antibodies to that of anticardiolipin (aCL), anti-beta2-glycoprotein I antibodies (anti-beta2-GPI), and lupus anticoagulant (LAC). METHODS: Serum IgG aPT, aANX, aCL, and anti-beta2-GPI levels were measured by solid phase enzyme immunoassay in the sera of 70 patients with systemic autoimmune diseases, 35 with antiphospholipid syndrome (APS) and 35 without APS. Medical records were analyzed, and associations of the antibodies with clinical features of APS were assessed. RESULTS: Patients with APS had higher frequency of aPT (p = 0.001) and aANX (p = 0.002) compared to patients without APS. Thrombotic events occurred more frequently in those with aPT or aANX than those without (p = 0.005, p = 0.006, respectively). The presence of aPT and aANX was found to be highly specific for APS. CONCLUSION: Measurement of aPT and aANX antibodies may be of value in confirming the diagnosis of APS, and in evaluating risk of venous and arterial thrombosis in patients with systemic autoimmune diseases.

Adult↗
PubMed2000

Membranous glomerulonephritis in a patient with inherited activated protein C resistance.

We present a patient with membranous glomerulonephritis, several clinical complications of the antiphospholipid syndrome and ulcerative colitis, but without lupus anticoagulant and antiphospholipid/cofactor antibodies. Immunological studies--other antibodies--were negative and failed to show enough criteria for any autoimmune diseases. Evaluation of her laboratory tests for hereditary thrombophilia revealed a heterozygous form of the Leiden mutation that might be associated with widespread vasculopathy. An interesting possibility is that the inherited activated protein C resistance could be an additional risk factor for vaso-occlusive manifestations appearing as a clinical sign of cardiovascular diseases and nephropathy.

Activated Protein C Resistance↗
PubMed1999

[Adult onset Still disease: comment on two cases].

The adult onset Still disease is a systemic disease of an unknown etiology. As a separate entity, it was described firstly in 1971. The diagnosis is problematic and based upon special criteria. In this study, we present the cases of two patients with adult onset Still's disease, causing several serious differential-diagnostic problems. In the beginning of the disease a high, remittent-intermittent fever was present which reacted well to salycilates. Almost simultaneously, a characteristic, confluent, no itching rash appeared on the trunk and limbs. Pain of little joints of the hands was an early symptom of the disease in both of the cases. Before the final diagnosis, the possibility of any infectious diseases, haematologic malignancies or other autoimmune disease had to be excluded. The aim of this work was to show an overall, up-to-date picture of the disease based on two typical cases.

Adult↗
PubMed1999

Bromine K-edge EXAFS studies of bromide binding to bromoperoxidase from Ascophyllum nodosum.

Bromine K-edge EXAFS studies have been carried out for bromide/peroxidase samples in Tris buffer at pH 8. The results are compared with those of aqueous (Tris-buffered) bromide and vanadium model compounds containing Br-V, Br-C(aliphatic) and Br-C(aromatic) bonds. It is found that bromide does not coordinate to the vanadium centre. Rather, bromine binds covalently to carbon. A possible candidate is active site serine.

Bromides↗
PubMed1999

The mitotic inhibitor ccs52 is required for endoreduplication and ploidy-dependent cell enlargement in plants.

Plant organs develop mostly post-embryonically from persistent or newly formed meristems. After cell division arrest, differentiation frequently involves endoreduplication and cell enlargement. Factors controlling transition from mitotic cycles to differentiation programmes have not been identified yet in plants. Here we describe ccs52, a plant homologue of APC activators involved in mitotic cyclin degradation. The ccs52 cDNA clones were isolated from Medicago sativa root nodules, which exhibit the highest degree of endopolyploidy in this plant. ccs52 represents a small multigenic family and appears to be conserved in plants. Overexpression of ccs52 in yeast triggered mitotic cyclin degradation, cell division arrest, endoreduplication and cell enlargement. In Medicago, enhanced expression of ccs52 was found in differentiating cells undergoing endoreduplication. In transgenic M.truncatula plants, overexpression of the ccs52 gene in the antisense orientation resulted in partial suppression of ccs52 expression and decreased the number of endocycles and the volume of the largest cells. Thus, the ccs52 product may switch proliferating cells to differentiation programmes which, in the case of endocycles, result in cell size increments.

Amino Acid Sequence↗
PubMed1999

A novel normalized retention factor in micellar electrokinetic chromatography.

Characteristic properties of the expression k'' = (t(m)-t(o))/(t(mc)-t(o)) and its applicability in micellar electrokinetic capillary chromatography (MEKC) were compared to the previous expression, k' = (t(m)-t(o))/t(o)(1-t(m)/t(mc)), introduced by Terabe. It was proved with theoretical calculations (curve shape analysis) that the properties of function k'' are in full accordance with the properties of the MEKC system and k'' could be applied advantageously to characterize hydrophobicity of the analytes. This conclusion is now supported by experimental data obtained with homolog series of alkylbenzenes and alkylphenones as well as with hydrophobic protected peptides. Migration times, k', k'' values, and software-calculated hydrophobicity data are summarized and analyzed in the present study. Since k'' is a normalized parameter, good relationships between the migration time, the software-calculated hydrophobicity, and the k'' values were obtained. Differences in hydrophobicity of the analytes could be estimated in a more realistic way with the aid of function k'' than by using function k'. Hydrophobicity data estimated on the basis of the k'' values proved to be in good accordance with the expectations based on the migration times and on the chemical structures of the compounds investigated.

Benzene↗
PubMed1999

The effect of isoproterenol on phospholamban-deficient mouse hearts with altered thyroid conditions.

The aim of the present study was to determine the effects of beta -adrenergic stimulation in wild-type and phospholamban-deficient mouse hearts with altered thyroid conditions. Hypothyroidism was associated with significant decreases in heart/body weight ratio in wild-type and phospholamban-deficient mice, whereas hyperthyroidism was associated with significant increases in heart/body weight ratio in both groups. Hypothyroid hearts of wild-type and phospholamban-deficient mice exhibited similar increases in beta -myosin heavy chain protein levels and decreases in alpha -myosin heavy chain protein levels. In hyperthyroidism, there were increases in the alpha -myosin heavy chain protein levels and these were similar in wild-type and phospholamban-deficient hearts. There were no detectable levels of beta -myosin heavy chain protein in the hyperthyroid hearts. The relative tissue level of phospholamban in wild-type hearts was increased (133%, P<0.01) in hypothyroidism, and decreased (69%, P<0.01) in hyperthyroidism, when compared to euthyroid controls (100%). Similar increases and decreases in SR Ca(2+)-ATPase protein levels were observed between phospholamban-deficient and wild-type hearts in hyperthyroidism and hypothyroidism, respectively. The basal contractile state of wild-type and phospholamban-deficient hearts was significantly depressed in hypothyroidism. On the other hand, the basal contractile state of wild-type and phospholamban-deficient hearts was significantly increased in hyperthyroidism. During beta -agonist stimulation of wild-type hearts, the responses in the rates of contraction and relaxation were highest in the hypothyroid group, followed by the euthyroid, and lastly by the hyperthyroid groups. There was a close linear correlation between the magnitude of the contractile parameter responses and the phospholamban/SERCA2 ratios in these hearts. However, the phospholamban-deficient hypothyroid, euthyroid, and hyperthyroid hearts did not exhibit any responses to isoproterenol, indicating that the alterations in the thyroid states of these hearts do not influence the effects of isoproterenol on cardiac function. These findings suggest that phospholamban is an important regulator of the heart's responses to beta -adrenergic stimulation under various thyroid states.

Animals↗
PubMed1999

Isotype distribution and clinical relevance of anti-beta2-glycoprotein I (beta2-GPI) antibodies: importance of IgA isotype.

The aim of this study was to evaluate the prevalence of IgG, IgA and IgM anti-beta2-GPI antibodies in anti-phospholipid syndrome (APS), and to establish the clinical significance of IgA type antibodies compared with the other isotypes. Anti-beta2-GPI antibodies were measured in the sera of 70 patients by solid-phase enzyme immunoassay in gamma-irradiated polystyrene plates coated with human purified beta2-GPI. Thirty-three out of the 70 patients were classified as having APS: three of them had primary, and 30 had secondary APS related to systemic lupus erythematosus (SLE). The remaining 37 patients had SLE without APS. Anti-beta2-GPI antibodies of IgG, IgA and IgM isotypes were present in 84.8%, 59.3% and 51.5% of patients with APS. Both the frequency and the level of each isotype were significantly higher in patients with APS. This association was very strong for IgA (P = 0.0004 for the antibody frequency and P < 0.0001 for the antibody level), as well as for IgG type antibodies (P < 0.0001 and P < 0.0001), whereas it was weaker for IgM (P = 0.01 and P = 0.04). A strong relationship was demonstrated between increased IgA anti-beta2-GPI antibody levels and a history of venous thrombosis, thrombocytopenia, heart valve disease, livedo reticularis and epilepsy. IgG anti-beta2-GPI antibodies were associated with the presence of lupus anticoagulant (LA) in addition to the main features of APS. However, antibodies of IgM isotype were related only to thrombocytopenia and heart valve disease. We recommend the evaluation of anti-beta2-GPI antibodies of IgA isotype in addition to IgG in patients with clinical suspicion of APS.

Antiphospholipid Syndrome↗
PubMed1999

Effect of plasmapheresis on ligand binding capacity and expression of erythrocyte complement receptor type 1 (CR1) of patients with systemic lupus erythematosus (SLE).

The functional activity and the expression of CR1 on the erythrocytes (E) of patients with SLE were, respectively, determined by measuring the binding to E of either complement-opsonized bovine serum albumin (BSA)-anti-BSA immune complexes (ICC) or specific anti-ECR1 MoAbs. We found that both the functional activity and levels of ECR1 in SLE patients homozygous for ECR1 high density allele were significantly lowered compared with healthy controls having the same allele. Soon after plasmapheresis there was a significant increase in E ICC binding activity, and this increased functional activity was stable. Moreover, plasmapheresis reduced the level of immune complexes demonstrable in the circulation of the patients. The expression of ECR1 determined with several different anti-CR1 MoAbs was also elevated as a consequence of plasmapheresis. This elevation was observed for both MoAb 1B4, which competes for the ICC binding site of ECR1, and for MoAb HB8592, which does not, but the time course for the increase in binding of the two MoAbs was different, in that the epitope recognized by MoAb 1B4 increased more rapidly. The present results, considered in the context of previous findings, suggest that more than one mechanism may be operative with respect to the effects of the plasmapheresis in increasing ECR1 levels defined by different epitopes on the molecule.

Alleles↗
PubMed1999

Antibodies against human heat-shock protein (hsp) 60 and mycobacterial hsp65 differ in their antigen specificity and complement-activating ability.

Although complement activation appears to have an important role both in the early and late phases of atherosclerosis, the exact mechanism of the initiation of this activation is still unknown. Since injuries of the endothelial cells are known to result in increased stress-protein expression we tested the complement-activating ability of recombinant human 60 kDa heat-shock protein (hsp60). Human hsp60 was found to activate the complement system in normal human serum in a dose-dependent manner. Activation took place through the classical pathway. The lack of complement activation in agammaglobulinemic serum indicates that the classical pathway is triggered by anti-hsp60 antibodies. Hsp60 activated complement in the sera of 74 patients with coronary heart disease as well, and a strong positive correlation (r = 0.459, P < 0.0001) was found between the extent of complement activation and the level of anti-hsp60 IgG antibodies but there was no correlation to the level of anti-hsp65 IgG antibodies. Further distinction between anti-hsp60 and anti-hsp65 antibodies was obtained from competitive ELISA experiments: binding of anti-hsp60 antibodies to hsp60-coated plates was inhibited only by recombinant hsp60 and vice versa. Our present findings indicate that anti-hsp60 and anti-hsp65 antibodies are distinct, showing only partial cross-reactivity. Since complement activation plays an important role in the development of atherosclerosis and the levels of complement-activating anti-hsp60 antibodies are elevated in atherosclerosis-related diseases, our present findings may have important pathological implications.

Adult↗