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T Mészáros

Publications and source records attributed to T Mészáros.

At least 19 recordsLinked to original sources
PubMed2001

Auxin and heat shock activation of a novel member of the calmodulin like domain protein kinase gene family in cultured alfalfa cells.

A calmodulin like domain protein kinase (CPK) homologue was identified in alfalfa and termed MsCPK3. The full-length sequence of cDNA encoded a 535 amino acid polypeptide with a molecular weight of 60.2 kDa. The deduced amino acid sequence showed all the conserved motifs that define other members of this kinase family, such as serine-threonine kinase domain, a junction region and four potential Ca2+ -binding EF sites. The recombinant MsCPK3 protein purified from E. coli was activated by Ca2+ and inhibited by calmodulin antagonist (W-7) in in vitro phosphorylation assays. The expression of MsCPK3 gene increased in the early phase of the 2,4-D induced alfalfa somatic embryogenesis. Heat shock also activated this gene while kinetin, ABA and NaCl treatment did not result in MsCPK3 mRNA accumulation. The data presented suggest that the new alfalfa CPK differs in stress responses from the previously described homologues and in its potential involvement in hormone and stress-activated reprogramming of developmental pathways during somatic embryogenesis.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

Multiple cyclin-dependent kinase complexes and phosphatases control G2/M progression in alfalfa cells.

Reversible phosphorylation of proteins by kinases and phosphatases plays a key regulatory role in several eukaryotic cellular functions including the control of the division cycle. Increasing numbers of sequence and biochemical data show the involvement of cyclin-dependent kinases (CDKs) and cyclins in regulation of the cell cycle progression in higher plants. The complexity represented by different types of CDKs and cyclins in a single species such as alfalfa, indicates that multicomponent regulatory pathways control G2/M transition. A set of cdc2-related genes (cdc2Ms A, B, D and F) was expressed in G2 and M cells. Phosphorylation assays also revealed that at least three kinase complexes (Cdc2Ms A/B, D and F) were successively active in G2/M cells after synchronization. Interaction between alfalfa mitotic cyclin (Medsa;CycB2;1) and a kinase partner has been reported previously. The present yeast two-hybrid analyses showed differential interaction between defined D-type cyclins and Cdc2Ms kinases functioning in G2/M phases. Localization of Cdc2Ms F kinase to the preprophase band (PPB), the perinuclear ring in early prophase, the mitotic spindle and the phragmoplast indicated a pivotal role for this kinase in mitotic plant cells. So far limited research efforts have been devoted to the functions of phosphatases in the control of plant cell division. A homologue of dual phosphatase, cdc25, has not been cloned yet from alfalfa; however tyrosine phosphorylation was indicated in the case of Cdc2Ms A kinase and the p(13suc1)-bound kinase activity was increased by treatment of this complex with recombinant Drosophila Cdc25. The potential role of serine/threonine phosphatases can be concluded from inhibitor studies based on okadaic acid or endothall. Endothall elevated the kinase activity of p(13suc1)-bound fractions in G2-phase alfalfa cells. These biochemical data are in accordance with observed cytological abnormalities. The present overview with selected original data outlines a conclusion that emphasizes the complexity of G2/M regulatory events in flowering plants.

CDC2 Protein Kinase↗
PubMed2000

Inhibition of serine/threonine-specific protein phosphatases causes premature activation of cdc2MsF kinase at G2/M transition and early mitotic microtubule organisation in alfalfa.

Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34cdc2/CDC28-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 microM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 microM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 microM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.

Chromosomes↗
PubMed1998

Capillary chromatography/microelectrospray mass spectrometry used for the identification of putative cyclin-dependent kinase inhibitory protein in Medicago.

A home-built capillary chromatography/microelectrospray system was used for peptide mass mapping of a putative cyclin-dependent kinase inhibitor protein with molecular mass of 8.5 kDa. The masses of identified tryptic fragments were then input to a protein database search routine. Daughter ion scans were done only on the most abundant tryptic fragments. On the basis of protein database search results and tandem mass spectrometric measurements the bioactive protein was identified as ubiquitin.

Amino Acid Sequence↗
PubMed1997

Oxidative stress induced by bloodless limb surgery on humans.

Measure of oxidative stress were studied in blood samples from 10 patients undergoing bloodless lower limb surgery. Ischaemia induced a significant increase in plasma hypoxanthine concentration and xanthine oxidase activity both in the operated leg and in the systemic circulation. Five minutes after reperfusion, ratio of xanthine oxidase/total xanthine oxidase and dehydrogenase activities rose moderately, whereas at 20 min xanthine oxidase accounted for all xanthine oxidoreductase activity in the systemic circulation. A significant increase in blood glutathione redox ratio, enhanced oxidation of haemoglobin to methaemoglobin and rise in plasma haemoglobin concentration were present only in the operated limb. Thus, although the level of the potential free radical generators rose significantly both locally and in the systemic circulation, oxidative stress, as indicated by blood glutathione and erythrocyte injuries, remained limited to the reperfused leg.

Aged↗
PubMed1997

Cell cycle phase specificity of putative cyclin-dependent kinase variants in synchronized alfalfa cells.

The eukaryotic cell division cycle is coordinated by cyclin-dependent kinases (CDKs), represented by a single major serine/threonine kinase in yeasts (Cdc2/CDC28) and a family of kinases (CDK1 to CDK8) in human cells. Previously, two cdc2 homologs, cdc2MsA and cdc2MsB, have been identified in alfalfa (Medicago sativa). By isolating cDNAs using a cdc2MsA probe, we demonstrate here that at least four additional cdc2 homologous genes are expressed in the tetraploid alfalfa. Proteins encoded by the new cdc2MsC to cdc2MsF cDNAs share the characteristic functional domains of CDKs with the conserved and plant-specific sequence elements. Transcripts from cdc2MsA, cdc2MsB, cdc2MsC, and cdc2MsE genes are synthesized throughout the cell cycle, whereas the amounts of cdc2MsD and cdc2MsF mRNAs peak during G2-to-M phases. The translation of Cdc2MsA/B, Cdc2MsD, and Cdc2MsF proteins follows the pattern of transcript accumulation. The multiplicity of kinase complexes with cell cycle phase-dependent activities was revealed by in vitro phosphorylation experiments. Proteins bound to p13suc1-Sepharose or immunoprecipitated with Cdc2MsA/B antibodies from cells at G1-to-S and G2-to-M phase boundaries showed elevated kinase activities. the Cdc2MsF antibodies separated a G2-to-M phase-related kinase complex. Detection of histone H1 phosphorylation activities in fractions immunoprecipitated with antimitotic cyclin (CyclinMs2) antibodies from G2-to-M phase cells indicates the complex formation between this cyclin and a kinase partner in alfalfa. The observed fluctuation of transcript levels, amounts, and activities of kinases in different cell cycle phases reflects a multilevel regulatory system during cell cycle progression in plants.

Amino Acid Sequence↗
PubMed1989

[Experience with total hip prosthesis].

Authors report on their material of total hip endoprosthesis, performed 30 May 1969--31 August 1988 on the Department of Orthopaedics of the Semmelweis University of Medical Science. In this period 1480 operations were made. The formerly and recently used operative technique and the types of the prostheses are described. The intraoperative, the early and the late complications and their treatment are also described. The formerly and recently used tactics of reoperation is reported and attention is called to the fact that the success rate of the replantation can be increased by an adequate technical skill.

Adult↗
PubMed1989

[Experience with giant cell tumors].

Authors describe, 64 cases of giant-cell tumour. 5 (9 per cent) was found in the latent, 32 (50 per cent) in the active and 27 (41 per cent) in the aggressive stage when first seen. The operative methods are described and these are determined first of all by the surgical stage of the giant-cell tumour, its size and localization, by the age of the patient and whether primary tumour or a recurrence is found. Based on their experiences, excochleation and filing is suggested in the latent and active stage of this tumour. In tumours in the agressive stage the so called wide resection in the healthy tissue is reasonable. In the rare malignant giant-cell tumour radical resection is suggested. Recurrence was found in 29 per cent after the first operation. Follow-up examinations show that 64 per cent of the patients is symptom free, in 33 per cent the main source of complaints is the consecutive arthrosis, 2 patients were lost in consequence of lung metastasis.

Arthrodesis↗
PubMed1988

The clinical diagnostic significance of serum antichondrocyte membrane antibodies in osteoarthritis.

In osteoarthritic patients significantly elevated level of antibodies against human chondrocyte membrane extract was found by double solid phase ELISA which seemed to be more specific for the disease than the antibody level of collagen types II, IX and XI. Altogether 86 patients with a mean age of 53.6 years and a ratio of 25% men and 75% women suffering from severe hip joint osteoarthritis were studied in comparison with 44 control persons with a mean age of 35.8 years and identical sex distribution. The specificity of reacting antibodies was proved partly by inhibition test and partly by the fact that the ELISA reaction could be produced only by proteins of the membrane extract bound to collagen (II) after affinity chromatography. The diagnostic importance of the methods is striking, in view of the lack of any other objective laboratory tests for the disease.

Autoantibodies↗
PubMed1984

The importance of minor collagenous chains in the articular cartilage.

This is a review of the present knowledge on the newly-described minor cartilage collagens. The authors deal with the nomenclature, methodology, structure and function of the minor collagens based on both literary data and their own results. The authors were the first to describe the occurrence of minor collagens in adult human articular cartilage and the change of the minor collagen content with age and osteoarthrosis [25]. The methods used by different groups for fractionation of minor collagens are different. As the recommended pepsin digestion used for solubilization of these collagens gives different results for the size of one of the minor collagens called M-collagen, special attention should devoted to the method used. The differential salt fractionation of pepsin-solubilized collagen was found the best. In this case the molecular structure of the M-collagen remained intact. In the neutral salt extraction technique recommended recently by Burgeson et al. [5], yield of collagen from sample is high, M-collagen is degraded. The greatest solubilization of collagen was achieved by the cyanogen bromide technique. The mixture of peptides from different proteins, however, requires further fractionation. The authors propose to investigate minor collagens in tissue samples obtained from biopsies and in synovial fluid.

Animals↗
PubMed1983

Minor collagens in arthrotic human cartilage. Change in content of 1 alpha, 2 alpha, 3 alpha and M-collagen with age and in osteoarthrosis.

The content and distribution of 1 alpha, 2 alpha, 3 alpha and M-collagens in human articular cartilage were studied. As controls, normal femoral heads and costal cartilage of autopsy material from newborn to 91-year-old persons were used. The osteoarthrotic cartilage was obtained from patients undergoing total hip replacement aged 45-80. The pepsin-digested cartilage collagen was fractionated by differential salt fractionation. The collagen content of the fractions was determined, and the fractions were separated by polyacrylamide slab gel electrophoresis. In the extracted collagen, the type II collagen varied from 82 to 97 per cent with increasing age. The 1 alpha, 2 alpha and 3 alpha chains decreased. M-collagen, especially of the high molecular weight components, disappeared with age. In osteoarthrosis three types of change - degeneration, new fibrocartilage formation on the surface of osteophyte and reparative cartilage - were separately studied. In all types of osteoarthrosis, an increase of minor collagens was found. In newly formed fibrocartilage, the reappearance of M-collagen was conspicuous. It is proposed that the three types of osteoarthrotic cartilage may be characterized on the basis of content and distribution of minor collagens.

Adolescent↗
PubMed1980

Quantitative analysis of the growth of the hip joint. A radiological study.

Growth of the hip joint is described on the basis of annual radiographs taken of the intact hip joints of 50 boys aged between 5-15 years. The ossification centre of the femoral head grows at a faster rate in breadth than in height. The growth rate in breadth of the bony centrum exceeds also that of the proximal metaphysis and, accordingly, in the case of normal ossification, the radio-anatomical condition of these two parts is characteristic of the age of the individual. The osseous acetabulum also grows at a faster rate in breadth than in depth. In the period studied up until the 15th year the width of the "articular space" gradually decreases. The ossification rate in the age group examined manifests--with slower and faster periods--a gradually declining tendency. The changes revealed by the radiographs have been interpreted from the viewpoint of bone development and an analysis is also given of the spatial conditions of ossification.

Acetabulum↗
PubMed1979

[The significance of tomography in the x-ray diagnosis of coxarthrosis (author's transl)].

Authors have made besides routine roentgenograms tomograms too in 50 patients with coxarthrosis of various severeness. For an assessment of the diagnostic value of tomography the routine roentgenograms and the tomograms were analysed comparatively. The investigations have shown that the tomography may give in certain cases great help in the judgement of progression and in the correct indication of operative methods in hip surgery.

Adult↗
PubMed1979

The pathologic new bone formation of an osteogenic sarcoma.

The authors describe the structure of bone and tumorous new bone formation of an amputated femur affected by osteogenic sarcoma. They studied a slide of the invaded bone using stereomicroscopic and comparative histologic techniques. The bone destruction induced by the tumor produces characteristic morphologic changes both in the cortical and in the cancellous bone. Investigation of the extraosseal tumorous bone formation is described together with its relation to the cortical bone. In the development of tumorous bone plates primary and secondary formations could be distinguished. The intraosseal, tumor-induced new bone/osteoid formation appears characteristically in the invaded marrow-spaces as a so-called "miniature spongiosa". In the zone adjacent to the tumor, reactive bony spines grow out from the surface of the normal spongy plates. These findings are also analyzed from the view of the roentgenologic findings.

Adult↗