Biomedical subjects

R Neuwirtová

Publications and source records attributed to R Neuwirtová.

At least 19 recordsLinked to original sources

PubMed2006

[Ubiquitins, proteasomes, sumoylation and therapeutic application today and in future for cancer and other diseases. I. Ubiquitin-proteasome system and the transcription factor NF-kappaB].

Proteasome is protein complex with proteolytic activity. Proteasomes are in addition to lysosomes the main proteolytic machinery of the eukaryotic cell. Proteins destined for degradation in proteasomes are marked by ubiquitinylation, which consists in attachment of polyubiquitin to relevant protein. The transport of polyubiquitinylated protein follows to proteasome, where protein is cleaved into small peptides. Besides polyubiquitin attachment to protein, monoubiquitinylation of proteins exists and has an important role in DNA repair, transcription of genes, endocytosis and signal transduction. The function of an important transcription factor NF-kappaB is connected with proteasome. NF-kappaB is activated after the proteolysis of its inhibitor IkappaB in proteasome. Ubiqutinylation and degradation of protein in proteasome and the activation of NF-kappaB play significant roles in taking proteins away and in expression of great numbers of genes important for the regulation of the cell cycle and apoptosis of cells. The inhibition of proteasomes has antiproliferative and antiinflammatory effects and opens new therapeutic approaches to a treatment of cancer and some inflammatory diseases. We divided the review into three parts: I. Ubiquitin-proteasome system and the transcription factor NF-kappaB, II. Sumoylation and neddylation as post-translational modification of proteins similar to ubiquitinylation and their significance and lastly III. Using of the knowledge of ubiquitin-proteasome system in cancer and other diseases therapy.

Animals↗

PubMed2006

[Ubiquitins, proteasomes, sumoylation and application today and in future for cancer and other diseases therapy II. Sumoylation and neddylation as posttranslational modifications of proteins and their ubiquitinylation and its significance].

Posttranslational protein modifications are effective devices that cells use to control the functions of proteins. Ubiquitin-like protein modifiers (Ubls) are posttranslationally attached to proteins by enzymatic reactions that are similar to ubiquitin conjugation. SUMO (small ubiquitin-related modifier) family proteins are the most intriguing Ubls. Sumoylation is the covalent attachment of SUMO to target proteins. Neddylation is the process that conjugates the ubiquitin-like polypeptide Nedd8 to the conserved lysines of cullins. Cullin family proteins organize ubiquitin ligase complexes to target numerous cellular proteins for polyubiquitinylation and subsequent proteasomal degradation. Despite the similarities in their structure and in enzymatic reactions Ubls and ubiquitin have distinct functions. In contrast with polyubiquitinylation that targets modified proteins to proteasome degradation, the biological consequences of sumoylation include the increase of protein stability. Sumoylation also helps in the protein transport from the cytoplasm to nucleus of cells, regulates transcriptional activities of proteins and mediates the binding of the protein to other proteins. Neddylation has importance for cell cycle control, signal transmission, cell differentiation and DNA repair. Recent studies linked sumoylation and neddylation of several proteins to important diseases (neurodegenerative diseases, acute promyelocytic leukemia, type I diabetes and other disorders). The regulation of these postranslational modifications may provide new targets for therapeutic intervention in several human diseases.

Humans↗

PubMed2006

[Auto- and alloreactivity of T lymphocytes in myelodysplastic syndrome].

BACKGROUND: Successful therapy with ATG and cyclosporine A in some myelodysplastic syndrome (MDS) patients led us to study the existence of T cells attacking autologous hemopoietic cells. In our study, we attempted to give the direct prove of autoreactive T cells in MDS (autoreactivity analysis). Simultaneously, we analysed the capacity of MDS patients to respond to allogeneic cells from unrelated individuals (alloreactivity analysis). METHODS AND RESULTS: Autoreactive lymphocytes directed against own bone marrow mononuclear cells were analysed using the modification of cell mediated cytotoxic reaction. With one exception we did not confirm the presence of autoreactive T cells among 10 patients examined. Analysis of alloreactivity was performed by means of standard cell mediated cytotoxic reaction and mixed lymphocyte reaction. Surprisingly, the cytotoxic response to allogeneic cells was negative in 11 MDS patients from 16 analysed. When comparing refractory anaemia (RA) and refractory anaemia with ring sideroblasts (RARS) patients, the proportion of negative results was higher in RA (78 %) than in RARS (40 %). In mixed lymphocyte reaction, the response of MDS cells to allogeneic cells of unrelated individual was positive in all tested patients. The preliminary testing of TNF and IFNgamma secretion examined in supernatants of effector cells showed impaired levels of both cytokines in RA and normal levels in RARS in accordance with the findings achieved in alloreactivity analysis. CONCLUSIONS: Autoreactive T cells were not found in MDS patients using our experimental arrangement. Analysis of alloreactivity showed the defect in effector--cytotoxic--phase of cell mediated cytotoxic reaction in the majority of MDS patients. The initial phase of this reaction represented in vitro by mixed lymphocyte reaction gave normal results. The possible reasons of disturbed alloreactivity and its relevance to immunity in MDS are commented in discussion.

Aged↗

PubMed2004

Accumulation of homoplasmic mtDNA point mutations in erythroblasts isolated from the bone marrow of patients with refractory anemia with ring sideroblasts (RARS).

It was hypothesised that mitochondrial iron overload in patients with refractory anemia with ring sideroblasts (RARS) results from mitochondrial DNA (mtDNA) mutations. To analyse the mtDNA sequence of iron storing mitochondria sensitively, we developed new protocols for selective erythroblasts isolation, mtDNA PCR amplification and sequencing. Using this approach, we found in each of the three RARS patients examined a unique spectrum of homoplasmic mtDNA point mutations affecting several mtDNA genes. Prediction analyses suggest that identified mutations do not result in major perturbations of mitochondrial functions and are tolerated. We discuss a mechanism explaining how the mutations identified may contribute to RARS pathogenesis.

Journal Article↗

PubMed2002

[The International Prognostic Scoring System for primary myelodysplastic syndrome].

A number of prognostic scoring systems for patients with myelodysplastic syndrome (MDS) have been introduced since FAB classification of the MDS in 1982. Recently, the International Prognostic Scoring System (IPSS), published in 1997 by Greenberg et al. [9] is based on the percentage of bone marrow (BM) blasts, cytogenetic abnormalities and number of cytopenias. We applied criteria of the IPSS on 205 patients (pts) with primary MDS (RA = 82, RARS = 49, RAEB = 42, RAEB-t = 8, CMML = 24 pts). IPSS discriminated within each of the FAB-subgroups: RA pts were present in low risk and intermediate (Int) I and II risk subgroups, RARS pts were separated into low and Int I, RAEB were distributed predominantly between Int I and Int II risk groups, RAEB-t in high-risk group, and CMML pts were distributed in all groups. In contrary to Greenberg's group of the MDS patients there are only three risk-groups in our study: low risk (score 0-0.5), intermediate (1-2) and high risk (> 2); the median survival and the risk of the evolution to the acute leukemia (p = 0.0001) are significantly different.

Aged↗

PubMed2002

[Cell clonality in myelodysplastic syndrome].

INTRODUCTION: Myelodysplastic syndromes (MDS) are classified as oncohematologic, clonal diseases. However, some MDS subtypes lack malignant clinical features. Literary data on the clonality of blood cells in MDS are controversial. Therefore we examined the clonality in the group of our own MDS patients. We were especially interested in the comparison of the clonality of myeloid and lymphoid cell line-ages. METHODS AND MATERIAL: Using X-chromosome inactivation methods based on polymorphism in human androgen receptor gene (HUMARA), iduronate sulphatase gene (IDS) and protein p55 gene, we assessed the clonality of granulocytes, monocytes and T-lymphocytes of 49 female patients with MDS and 12 control women of various ages. RESULTS: Though the results were heterogeneous, certain trends were observed: most frequently monoclonality of monocytes was found (51%), granulocytes were monoclonal in 33% of cases, monoclonal T lymphocytes only in 8% of cases. There was no case with monoclonal T lymphocytes and simultaneously polyclonal myeloid cell fractions. Results differ in relation to the subtypes of MDS. Among controls we observed monoclonality of myeloid cells in one case of an old lady. WE CONCLUDE: The results confirm the presence of malignant clone of myeloid cells in MDS, which can be of variable size. The examination of the clonality in MDS can be significant for the therapy decision. Monoclonal myeloid cells are found least frequently in refractory anemia, most frequently in RAEB-T. Monoclonality of cells in sideroblastic anemia is interesting. The prevailing polyclonality of T lymphocytes in MDS can be explained by the presence of a long-lived cell population originating from the period before the development of MDS. The role of the polyclonal memory T cells in the antitumor immunity in MDS is discussed.

Adult↗

PubMed2001

[The comet assay: principles of the method and clinical utilization].

BACKGROUND: Single cell gel electrophoresis or comet assay is used at present in the world to study of DNA damage, DNA repair and apoptosis. The aim of the work is to introduce the principle of comet assay to the medical community and to give a basic survey of its possible clinical applications. The article includes our first experience with this method in detection of apoptosis in bone marrow cells of patients with myelodysplastic syndrome (MDS). METHODS AND RESULTS: The whole bone marrow aspirates from 6 patients with MDS and 7 control persons were processed by alkaline version of comet assay and the degree of DNA fragmentation in individual cells was quantified using Image Analysis System. In comparison with controls, the patients with diagnosis RA and RARS exhibited in bone marrow significantly elevated number of cells with high level of DNA breaks, reflecting most probably the apoptotic cleavage of DNA. In contrast, the patient in proliferative stage of the disease (MDS-CMML-->AML) exhibited decreased frequency of apoptotic cells, well below the control level. CONCLUSION: Our results correspond with the data published on the occurrence of apoptosis in particular types of MDS. Comet assay represents a simple and cheap technique, applicable in clinical hematology to specify the diagnosis, to monitor the disease progress and efficacy of therapy not only in patients with MDS but also in other diseases resulting from an imbalance between proliferation and apoptosis.

Adult↗

PubMed2001

[Will knowledge of the mechanisms of apoptosis lead to new therapeutic procedures?].

Apoptosis (programmed cell death) ensures under physiological conditions cell homeostasis. Under pathological conditions excessive apoptosis, premature apoptosis or delayed or infinite apoptosis of cell is a sign of various serious diseases. Due to intensive research in this field it proved possible to assess nowadays at a molecular level a number of pro- and anti-apoptotic factors and their function in the process of apoptosis. Apoptosis proceeds by external as well as internal pathway. Factors involved in apoptosis are studied from the aspect of their possible therapeutic application in tissue cultures, experimental animals, and there are already some initial reports from human pathology. Delayed or infinite apoptosis is a typical property of tumor cells. So far most attention was paid to two ways of apoptosis induction of tumor cells: suppressed translation of the antiapoptic factor Bcl 2 by means of an antisense nucleotide and induction of apoptosis by TRAIL (TNF related apoptosis inducing ligand). Conversely a delay of premature apoptosis gives hope for hitherto untreatable neurodegenerative diseases, myelodysplastic syndromes, ischaemic events and some severe infections. This is achieved by means of peptides inhibiting caspases. Provided that modulation of cell apoptosis will not be associated with unacceptable side-effects, it will become a new therapeutic approach in hitherto inadequately curable diseases.

Animals↗

PubMed2001

Myelodysplastic and myeloproliferative type of chronic myelomonocytic leukemia--distinct subgroups or two stages of the same disease?

Several authors have tried to solve the problems in the classification of CMML. A fully suitable classification does not exist. The goal of our study was to determine common and different signs of MD and MP type of CMML and to observe frequency of shifts from MD to MP-CMML. Sixty nine CMML patients were divided according to FAB proposal into two groups: 31 patients into the MD group (WBC < or = 13 x 10(9)/l) and 38 patients into the MP group (WBC < or = 13 x 10(9)/l). Presenting features and the course of the disease in both groups were evaluated. The median age of patients was not different in both groups (71.5 and 74 years, respectively), male/female ratio was 1.1 and 2.4, respectively. The median follow-up time was 15.5 months (1-58.8) in MP group and 24 months (2-118) in MD group. In MP group splenomegaly, hepatomegaly, lymphadenopathy, abnormal karyotype and skin involvement were found more often than in MD group. Median LDH value was higher in MP group. Probability of survival was higher in the MD group than in MP group (median 30 and 11 months, respectively). Leukaemia transformation frequency was similar in both groups. In 12 out of 24 (50%) MD group patients WBC increased during the course of the disease over 13 x 10(9)/l. Oscillation of WBC values below and over 13 x 10(9)/l was observed in three patients. During the follow-up time number of patients with splenomegaly and/or immature granulocytes in the PB increased. After inclusion of 12 patients who shifted from MD to MP group a new CMML group resulted characterised by longer median survival (17 months) due to a higher number of patients in an earlier stage of the disease. Failure of evolution of myeloproliferative signs and lower frequency of AL in the remaining group might be explained by an early stage of CMML, untimely deaths due to unrelated causes and/or by patients suffering of RA with monocytosis rather than of CMML. In summary, our data suggest, that evolution from MD-CMML to MP-CMML is a frequent event and that MD-CMML could be the early stage of CMML in most of cases. The WBC at diagnosis as the single criterion for subclassification of CMML does not seem to be fully justified. We propose that CMML should not be divided in MD and MP types and that monitoring of patients and search for other signs of myeloproliferation such as PB immature granulocytes, splenomegaly, lymphadenopathy, skin involvement, pleural or peritoneal effusions, spontaneous growth of CFU-GM in vitro should be taken in consideration for a better classification of CMML, which would have an impact on the therapeutic approach.

Adult↗

PubMed1998

[Use of cyclosporin A in hematology].

We present an overview of clinical conditions where cyclosporin A (CyA) could be used in the treatment of hematological diseases. CyA is an effective immunosuppressive agent. It has long been successfully used in organ transplants and bone marrow transplants. The strong immunosuppressive effect of CyA makes this agent useful in various autoimmune diseases. The indication of CyA in certain hematological diseases has recently been steadily expanding. Based on the influence of CyA on cell immunity, the creation of cytokines and subsequently on humoral immunity we try to elucidate or justify its use in specific hematological diseases with regards to their pathophysiology. The common denominator to the diseases discussed below is a certain form of autoaggression. We include for example idiopathic autoimmune hemolytic anemia (AIHA) idiopathic thrombocytopenic (ITP), Evans syndrome, pure red cell aplasia. In certain sense we can include here even aplastic anemia (AA) and myelodysplastic syndrome (MDS). Furthermore, it is possible to use CyA for its ingerence to the proliferation and activation of T-cells in some T-lymphoproliferations and in histiocytoses. In B-lymphoproliferation the use of CyA will probably require further studies. We briefly note the possibility of influencing multiple drug resistance (MDR) with CyA.

Cyclosporine↗

PubMed1998

Cyclosporin A therapy in hypoplastic MDS patients and certain refractory anaemias without hypoplastic bone marrow.

We report 17 cytopenic patients with myelodysplastic syndrome (MDS) of refractory anaemia (RA) subtype with hyper-, normo- or hypo-cellular bone marrow (BM), who were treated with cyclosporin A (CyA). Substantial haematological response was observed in 14 patients (82%): their anaemia improved and all transfusion-dependent patients achieved transfusion independence. Complete trilineage recovery was observed in four patients (23%). The CyA therapy has not yet failed in any of the 14 successfully treated patients during follow-up times ranging from 5 to 30 months. CyA was well tolerated in 14 patients; serious side-effects required termination of the therapy in three patients in whom the blood count rapidly deteriorated to former levels upon cessation of therapy. Two patients benefited from a combination therapy of CyA and erythropoietin. Six patients experienced various autoimmune phenomena. CyA could thus offer an alternative treatment for certain MDS patients with RA regardless of hyper-, normo- or hypo-cellularity of bone marrow (BM). The mechanism of the beneficial effect of CyA is discussed and remains the subject of an ongoing study.

Adult↗

PubMed1997

[Mixed myelodysplastic and myeloproliferative syndromes].

BACKGROUND: An injury to the hemopoietic stem cell may lead to the aplasia of hemopoiesis, myelodysplasia and to an unregulated myeloproliferation. There is not a strict demarcation of them, so that mixed syndromes can develop as are hypoplastic syndromes on one side and mixed myelodysplastic and myeloproliferative syndromes (MDS-MPS) on the other side. METHODS AND RESULTS: Among our 616 pts with MDS we looked for those cases, who had beside myelodysplasia signs of myeloproliferation with increased number of blood cells. They were examined in detail including bone-marrow histology, bone marrow cultivation, cytogenetics and bcr-abl gen. Signs of MDS-MPS were found in 22 patients at the first contact with the patient (13 patients had thrombocytemia and 9 patients had leukocytosis). Further 7 patients were diagnosed as MDS, proliferative syndrome developed after several months (MDS-MPS in evolution). The level of thrombocytemia was relatively stable, the number of leukocytes was progressive. All subtypes of MDS were found. All subjects had variable degree of anemia. Ring-sideroblasts and myelofibrosis were frequent finding in MDS-MPS. Men prevailed in patients with leukocytosis. Cytogenetic and cultivation findings were similar to MDS cases, deletion of long arm of chromosome 20 was present in 3 patients. Five patients transformed to acute myeloid leukemia. CONCLUSIONS: Sings of myelodysplasia and myeloproliferation were found in 4% of our MDS patients, designated as mixed myelodysplastic and myeloproliferative syndrome (MDS-MPS). In this syndrome beside evident signs of myelodysplasia thrombocythemia or leukocytosis with the release of bone marrow precursors are present. In only one case polycythemia was encountered.

Adult↗

PubMed1996

Mixed myelodysplastic and myeloproliferative syndromes.

Aplastic anemia, myelodysplastic syndromes (MDS) and chronic myeloproliferative diseases (MPD) are stem cell disorders. There is no clear-cut demarcation of them. Hypoplastic MDS displays features of aplastic anemia and MDS, on the other side mixed myelodysplastic and myeloproliferative syndromes (MDS-MPS) develop. In our collection of 566 MDS patients, features of myelodysplasia as well as myeloproliferation, MDS-MPS, were present in 25 patients (4.4%). Twelve patients had at the time of diagnosis megakaryocytic proliferation and thrombocythemia beside signs of MDS, and seven had myelodysplasia with granulocytic proliferation and leukocytosis. In another six patients, MDS was the first diagnosis and the proliferative phase developed later during the course of the disease. These patients can be characterized as MDS-MPS in evolution. All subjects had a variable degree of anemia. While the level of thrombocythemia has been relatively stable, the number of leukocytes has been progressive, but rarely extended beyond 100 x 10(9)/l. Ring-sideroblasts and myelofibrosis were frequent findings. Two more homogeneous MDS-MPS groups emerged in our analysis: sideroblastic anemia with thrombocythemia and a group fulfilling the criteria of Philadelphia chromosome negative and bcr-abl negative "atypical chronic myeloid leukemia (aCML)'. One patient with thrombocythemia and three with leukocytosis (23%) transformed to acute myeloid leukemia (AML). Men prevailed (12/13) in patients with leukocytosis and MDS-MPS in evolution. Of the 46% MDS-MPS patients with chromosomal aberrations, del(20)(q) is of interest.

Adult↗

PubMed1994

[Administration of granulocyte-macrophage colony growth factors in the treatment of postcytostatic myelosuppresion in oncohematologic patients].

BACKGROUND: Growth factors for granulocytic and granulocyte-macrophage series (G-CSF and GM-CSF) in the form of recombinant proteins are used in various leukopenias. The aim of this work was to follow the effect of GM-CSF (Leucomax Sandoz) in myelosuppression after the therapy with cytotoxic drugs. METHOD AND RESULTS: Leucomax was given to 22 patients with oncohematological disease (3 patients with acute lymphoblastic leukemia, 5 patients with various myeloid malignacies, 4 myelomas and 10 patients with non-Hodgkin lymphomas). In comparison to the literary data lower doses of Leucomax were used, it is 150-200 micrograms a day and patient. The length of administration of the growth factor was reduced to the shortest possible time according to the leukocyte count monitoring. Leucomax administration was started when leukocytes dropped below 1.10(9), in patients with severe leukopenias after repeated chemotherapy Leucomax was applied earlier. From 17 patients treated for sufficiently long period of time 70% responded to the GM-CSF application without any serious side-effects. In most cases, with the exception of myeloma, the growth factor was applied for 4-10 days. The leukocyte increase above 3 x 10(9) appeared in 3-8 days after the start of the treatment. CONCLUSIONS: Correctly indicated application of growth factors in postcytostatic myelosuppression is a great contribution to antitumor therapy. According to our experience in most cases 5-7 days of the daily dose of 150-200 micrograms of GM-CSF is sufficient for the stimulation of leukopoiesis. In postherapeutic myelosuppression in acute myeloblastic leukemia the growth factor should be used only as a life saving therapy since it can stimulate the leukemic cell population.

Adult↗

PubMed1992

[Growth factors in hematology].

New experimental findings on the mutual regulation of growth, differentiation and function of human blood cells by growth factors offer the opportunity to use these factors in the treatment of haematological diseases. The hitherto known growth factors are divided into four basic groups: 1. haematopoietic growth factors proper [multi-CSF (IL-3), GM-CSF, G-CSF, M-CSF, erythropoietin, lymphopoietin (IL-7) and megakaryopoietin (IL-11)], 2. cytokines (IL-1 to IL-11, TFN)., 3. other growth factors (PDGF, FGF, MGF) and 4. so-called negative regulators of haematopoiesis (IFN, MIP, TGF beta and IL-10), some of which support the differentiation of stem cells. Before growth factors can be routinely used in clinical work, it is essential to acquire closer knowledge of their interrelations, the activity of their receptors and natural or acquired inhibitors in vivo.

Growth Substances↗

PubMed1992

[Cytosine arabinoside in low doses in the treatment of myelodysplastic syndrome. Czechoslovak MDS Cooperative Group].

The authors present an account of the therapeutic results with small doses of cytosine arabinoside--20 mg/m2/day--in 56 patients where in almost 10% of the patients long-term "complete" remission was achieved and in 22% partial remission. When very small doses were used, i.e. 5 mg/m2/day, only one partial remission was achieved in a total number of 10 patients. From analysis of the therapeutic results some practical conclusions can be drawn which are listed in the discussion. So far we do not know effective treatment of myelodysplastic syndrome and recommend therefore to test in suitable patients small doses of ARA-C, despite the fact that a favourable response to this treatment can be expected only in about one third of the patients.

Adult↗

PubMed1990

Neutralization of inhibitory activity derived from cells of MDS patients and ML-2 cell line by monoclonal antibodies against H and L-subunit-rich ferritins.

Monoclonal antibody 2A4 against human heart ferritin and a polyclonal antibody against human placental ferritin inactivated the suppressor activity present in media conditioned by cells of patients with myelodysplastic syndrome (MDS). These antibodies also neutralized the inhibitory activity released by cells of myeloid leukemic ML-2 cell line. In contrast, a monoclonal antibody against the ferritin L subunit did not neutralize the inhibitory activity of the media conditioned either by the cells of patients with MDS or by the ML-2 cell line. Neutralization of the inhibitory activity present in supernatants of cells of MDS patients and the ML-2 cell line by monoclonal antibodies against the H subunit of ferritin strongly indicates that the inhibitory activity resides in the acidic isoferritin molecule.

Antibodies, Monoclonal↗

PubMed1990

Agranulocytosis in a patient with primary Sjögren's syndrome.

The authors describe a case of primary Sjögren's syndrome, which was complicated with severe autoimmune agranulocytosis quite sensitive to immunosuppressive therapy. Agranulocytosis is a very rare complication of this autoimmune rheumatic disease as opposed to leucopenia. A remarkable feature of the presented case is the fact that correct diagnosis of primary Sjögren's syndrome has not been settled for almost 25 years. The disease has manifested only in the form of arthropathy imitating rheumatoid arthritis.

Agranulocytosis↗