PubMed Health⌕ Search

Biomedical subjects

A Vítek

Publications and source records attributed to A Vítek.

At least 19 recordsLinked to original sources
PubMed1997

[Analysis of HLA class I molecules using isoelectric focusing. Its application in selection of bone marrow donors].

BACKGROUND: Differences between HLA proteins class I are assessed by serological typing using HLA allo-antisera. This method suffices for the assessment of HLA signs in allogenic transplantations of bone marrow in genotypically identical siblings. However, it does not suffice in the selection of donors from the wider family of a related or not related donor from the register of voluntary bone marrow donors. In order to assess the polymorphism of the HLA-class I not detected by serological typing other more sensitive techniques are introduced. In the authors department one-dimensional isoelectric focusing was introduced as an auxiliary method for evaluation of identity of molecules in HLA-class I between bone marrow recipient and donor. METHOD AND RESULTS: The authors introduced the method of one-dimensional isoelectric focusing which uses for detection of molecules of HLA-class I a polyclonal antibody against heavy chains of HLA molecules class I and a secondary antibody labelled by alkaline phosphatase. Forty-one pairs of bone marrow donors and recipient were examined. In six instances, i.e. in almost 15%, the authors detected by isoelectric focusing disagreement in HLA molecules class I. The authors present three interesting pairs of donors and recipients where isoelectric focusing helped with the selection of a suitable bone marrow donor. CONCLUSIONS: The isoelectric focusing is at present another method which helps to reveal differences in HLA class I molecules. When methods of DNA analysis are introduced to recognize alleles of the HLA-I class, correlation with serologically and biochemically assessed variants wil be an essential guide in the evaluation of the final typing of HLA molecules class I.

Bone Marrow Transplantation↗
PubMed1997

[Frequency of cytotoxic and helper T-lymphocyte precursors in donors with alloreactivity to recipient histocompatibility antigens. Possible use in predicting acute graft vs host disease in bone marrow transplantation].

BACKGROUND: The utility of cytotoxic T lymphocyte precursor (CTLp) and helper T lymphocyte precursor (HTLp) frequencies estimation for detecting alloreactivity and for the prediction of acute graft versus host disease (aGVHD) has been evaluated. METHODS AND RESULTS: The limiting dilution assay and a maximum likelihood statistical programme were used for CTLp and HTLp frequency estimation. A high CTLp frequency suggesting the presence of hidden class I mismatches was detected in 41.2% of unrelated pairs. HLA-A and -B matched by serological typing and DRB1 and DQB1 matched by DNA analysis. Severe aGVHD (grade III-IV) occurred in all patients of this group who underwent bone marrow transplantation (BMT). In two patients of the three evaluated with low pretransplant CTLp frequency a mild form (grade I) or no aGVHD developed after unrelated BMT. Positive frequency of alloreactive HTLp was found in 50% of HLA matched unrelated pairs. The comparison of CTLp and HTLp values in the same individuals showed that these two methods are not fully alternative in detecting alloreactivity. In the group of HLA identical siblings, 18.7% of positive HTLp results were only found. Besides HLA-DP incompatibilities, the differences in non-HLA genes could cause this alloreactivity. CONCLUSIONS: CTLp assay has a potential for the prediction for aGVHD development following BMT from HLA matched unrelated donors. CTLp results suggest the necessity of more accurate class I typing in these cases. The comparison of CTLp and HTLp frequencies showed that the results can differ in some unrelated donor-recipient BMT pairs suggesting the convenience of simultaneous performing of both assays for the alloreactivity assessment. More cases have to be considered to determine the relationship between pretransplant HTLp frequency and posttransplant aGVHD development in HLA identical siblings.

Acute Disease↗
PubMed1996

[Donor selection for allogenic bone marrow transplantation from 1991 to 1995. (The Prague Center for Bone Marrow Transplantation)].

BACKGROUND: The prerequisite of successful transplantation of haematopoietic stem cells is to find a suitable, i.e. HLA matched bone marrow donor. In the submitted paper the authors give an account of the strategy of selection of bone marrow donors, as practised by the Prague transplantation group. METHODS AND RESULTS: In 1991 to 1995 (end of first quarter) the authors sought suitable bone marrow donors for 421 patients where an allogenic bone marrow transplantation was indicated. During that period 95 transplantations were performed (22.5% of all indicated cases), incl. 82 from siblings (86.3%) of the implemented allogenic bone marrow transplantations). A HLA matched donor from the wider family circle was selected for 15 donors, transplantation were performed in 6 patients (6.4% of the implemented allogenic bone marrow transplantations). An unrelated bone marrow donor was sought for 41 patients as no donor was found in the wider family. Transplantation was implemented in 7 of these patients (7.3% of the implemented transplantations. CONCLUSIONS: With the increasing experience of our transplantation centre, no doubt, the ratio of other than sibling transplantations of bone marrow will increase. At present it accounts for 13.7%. The task of our HLA group must be selection of donors matched as well as possible with the recipient according to all available tests of tissue compatibility - from the wider family circle as well as from the register of unrelated donors.

Bone Marrow Transplantation↗
PubMed1996

The search for HLA-compatible bone marrow donors. Procedure currently used in the Institute of Hematology and Blood Transfusion, Prague.

The search for compatible donors is based on the HLA types of donors and recipients. HLA-A, -B and -DRB1 antigens or alleles must be unequivocally typed in donors and recipients. The typing of HLA-DQB, -DPB and -C gene products is also useful to characterize the HLA phenotype, but it is not absolutely necessary in the donor selection. The standard serological methods using alloantisera and one-dimensional isoelectric focusing are used for the typing of HLA class I antigens. Recently, DNA analysis of class I alleles has been introduced. In HLA class II typing the serological analysis was generally replaced by DNA analysis. In addition to typing techniques that determine the individual HLA alleles or HLA gene products, the cellular matching techniques are used in the selection procedure (mixed lymphocyte culture, cytotoxic T lymphocyte precursor frequency assay, and IL-2-producing helper T lymphocyte precursor frequency assay). The cellular matching techniques determine the compatibility in the regions of HLA comprising several HLA loci; some of them may detect minor histocompatibility (non-HLA) gene disparities as well.

Bone Marrow Transplantation↗
PubMed1995

[Results of induction therapy in newly diagnosed acute myeloid leukemias in study 911 at the Institute of Hematology and Blood Transfusion].

Thirty-seven patients with de novo acute myeloid leukemias were admitted to the Institute of Hematology and Blood Transfusion in Prague in February 1991-December 1993. Their age was 18-85 years with a median of 46 years. Two patients died on the day of admission, chemotherapy was initiated in 35 patients. Altogether 27 patients (77%) achieved complete remission (CR), i.e. 18 (81%) of 22 patients younger than 55 years and 9 (70%) of 13 patients older than 55 years. Only 7 (35%) of 20 patients achieved CR after a single therapy course 3/7 consisting of 3 doses of daunorubicin 45 mg/m2 on days 1, 3, 5 and cytosine arabinoside 150-200 mg/m2 every 12 hours for 7 days. However, 8 (61%) of 13 patients achieved CR after a single treatment course 4/7 with 4 doses of daunorubicin 45 mg/m2 on days 1, 3, 5, 7 and identical doses of cytosine arabinoside as in the 3/7 treatment. We used the course with 10 high-doses of cytosine arabinoside 2000 mg/m2 every 12 hours and daunorubicin 45 mg/m2 on days 4 and 5 (treatment HDAC/DNR) as the 1st, 2nd or 3rd induction therapy in 12 patients and 9 (75%) of them achieved CR. The treatment was associated with a high toxicity. An intensified therapy 3/7h similar to the 3/7 one but with the doubled dose of cytosine arabinoside 300-400 mg/m2 on days 5-7 was given to 5 patients as the 2nd induction but it did not improve the CR rate and it was associated with a high toxicity similar to the HDAC/DNR therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

[Treatment of chronic myeloid leukemia with bone marrow transplantation at the Institute of Hematology and Blood Transfusion in Prague].

The outcomes of bone marrow transplantation (BMT) performed at the Institute of Haematology and Blood Transfusion from April 1988 to December 1994 in 31 patients with chronic myelogenous leukemia are presented. Age of the patients range from 18 to 49 years, median 34 years. Male:female ratio was 1.58:1. The conditioning regimen consisted of Cyclophosphamide and total body irradiation (TBI) or Busulfan and Cyclophosphamide. The results are evaluated as of January 1, 1995. Nineteen patients (61.3%) are alive, 12 patients (38.7%) died. The causes of death are discussed. The median time of follow up all patients is 10.4 months, range 0.3-81.5. The median time of follow up of surviving patients is 21.8 months, range 2.5-81.5. Probability of 2 years survival by Kaplan-Meier analysis is 58 +/- 10%. Of the 24 transplanted in the first chronic phase, 18 patients are alive. Of the 7 transplanted in advanced phase of the disease, 1 patient is alive. Of the 27 patients, who received bone marrow from an HLA identical sibling, 19 are alive. Of the 4 patients who received bone marrow from other donor than an HLA identical sibling, none is alive. Acute GvHD III.-IV. grade developed in 5 patients (16.1%), moderate and severe chronic GvHD developed in 11 patients (31.5%). Cytogenetic relapse was diagnosed in 1 patient, hematological relapse in 2 patients. Karnofsky scores of patients surviving after BMT range from 30% to 100%, median 90%.

Adolescent↗
PubMed1994

[Late and slow diagnosis of acute promyelocytic leukemias--the main cause of early death].

Acute hypergranular promyelocytic leukemia (AML M3) belongs to malignant diseases leading very rapidly to death. Immediate treatment based on early diagnosis may cure one third of patients. The typical finding in peripheral blood of patients is pancytopenia with or without atypical promyelocytes. In published studies only 15-25% patients exhibit leukocyte counts above 10 x 10(9)/l. Five of our ten patients studied had leukocyte count above 10 x 10(9)/l. The difference might be in connection with late and slow diagnosis of AML M3. AML is not taken into consideration during medical examination even if the disease occurs in medical family. Thus we describe clinical signs of AML M3 that could be divided into three main groups: bleeding, infections and anemia. In patients with bleeding or anemia or with infections repeating within a short period or with an infection and concurrent signs of bleeding or anemia the complete blood cell count should be examined immediately. If blood cell count abnormalities are found the patient should be sent immediately to hematology unit for further examination and treatment. Early diagnosis enables to start "differentiation therapy" with all-trans retinoic acid that could be administered as monotherapy only in patients with leukocytes below 5 x 10(9)/l. Early diagnosis of AML M3 might ameliorate the fate of patients, since four of our five patients referred to us with elevated leukocyte counts expired in the first five days.

Adult↗
PubMed1991

[The effect of thrombocytapheresis on hematologic, biochemical and immunologic indicators].

The authors investigated in 33 separate donors the influence of thrombocytapheresis on haematological, biochemical and some immunological parameters. The paired t-test revealed a statistically significant increase of values of total proteins, aspartate aminotransferase, immunoglobulin A, alpha 1 antitrypsin, transferrin and the C4 component of complement seven days after apheresis and a significant increase of thrombocyte, total protein, alkaline phosphatase, immunoglobulin A, orosomucoid, and transferrin levels two weeks after apheresis. A significant decrease of haemoglobin values was recorded 7 and 14 days after apheresis. As the revealed changes of the investigated parameters are within the physiological range of the healthy adult population, the authors conclude that thrombocytapheresis does not have an adverse effect on the health status of donors.

Adult↗
PubMed1990

[The significance of the thrombocyte crossmatching test].

The authors investigated the dependence of the results of the crossover test with thrombocytes and lymphocytes of the donor and serum of the recipient on the rise of thrombocytes 1 and 24 hours following administration of a thrombocyte concentrate. The clinical condition of the patient at the time of thrombocyte administration was taken into account. The donor of thrombocytes isolated in a blood element separator was selected from a panel of cca 800 subjects with previously assessed HLA antigens. A total of 36 administered concentrates was evaluated. From the assembled findings it may be concluded that the result of thromboconcentrate transfusion is significantly influenced by adverse clinical factors in the patient such as splenomegaly, haemorrhage, febrile conditions. A positive crossover lymphocytotoxic test can predict reliably the ineffectiveness of thrombocyte administration. A positive crossover test with the donor's thrombocytes does not affect significantly the success of the transfusion. It seems thus that for the fate of administered thrombocytes the presence of HLA antibodies is decisive and not the presence of specific thrombocytic antibodies.

Antibodies↗
PubMed1990

[Therapeutic effectiveness of thrombocyte concentrates in relation to the results of the lymphocytotoxicity test].

The authors analyze the effect of transfusions of 211 thrombocyte concentrates to polytransfused patients in relation to the results of the crossover test between donor and recipient, using the lymphocytotoxic test (LCT). In negative LCT tests the adequate and inadequate effect was 50%. After elimination of non-immune influences (splenomegaly, febrile temperature) the percentage of adequate effects rose to 70%. In LCT positive results the effect of administration of thrombocyte concentrates declined to 30%. The authors discuss practical possibilities and ways to select suitable donors to achieve an optimal therapeutic effect of substitution therapy.

Blood Transfusion↗
PubMed1989

[Comparison of the Haemonetics V50, Fenwal CS 3000 and IBM 2997 blood separators].

Haemonetics V 50 (HV-50), Fenwal CS 3000 (FCS-3000) and IBM 2997 separators are compared according to the results of donor plateletaphereses. The mean platelet yield of HV-50, FCS-3000 and IBM-2997 was 464 X 10(9), 551 X 10(9) and 468 X 10(9) respectively (the difference both between FCS-3000 and HV-50 and between FCS-3000 and IBM-2997 being significant - p less than 0.01). The median leukocyte contamination of platelet concentrates was 0.3 X 10(9), 0.2 X 10(9) and 5.3 X 10(9) respectively (the difference between FCS-3000 and HV-50 being not significant). The separators are further compared on the basis of platelet concentrate volume, erythrocyte contamination of thromboconcentrates, processing time, donor and staff convenience, our experience concerning product reliability and service quality, and finally the price of both the separators and the disposables.

Adult↗
PubMed1985

Consensus symmetry pattern in E. coli promoter sequences.

A computer method was used to select two subgroups in 172 Escherichia coli promoter nucleotide sequences characterized by "standard" 17 bp and "non-standard" 17 +/- 2 bp spacing between the Pribnow box and -35 region. The conservation of the two-fold rotational (2f) and true palindrome (tp) symmetry relations was determined between nucleotide doublets in both promoter subgroups which represent consensus symmetry patterns. Statistically significant symmetries were primarily distinguished from those established by the nucleotide sequence conservation. The consensus symmetry pattern of standard promoters involves 45 of the 60 promoter nucleotide positions at which less strongly conserved and non-conserved sequences were mostly occupied (per se). They also show a high level of symmetry centre conservation. The conservation of the statistically significant 2f symmetry centres at positions -4.5 and -31.5 suggests partial conservation of the Pribnow box and -35 pentamer in the codogenic strand in an opposite orientation, respectively. The non-standard promoters differ from the standard ones by the consensus symmetry pattern and by the 2f and tp symmetry centre distribution with an overall lower degree of symmetry conservation in the -35 region. It has been suggested that the conserved symmetry relations provide an additional condition necessary for the specific interaction of RNA polymerase with the promoter sequence to initiate transcription.

Base Sequence↗
PubMed1979

The arrangement of nucleotides in the coding regions of natural templates.

The relation of the nucleotide sequences in the coding regions of natural templates and of the short nucleotide sequence in 3' terminus of 16 S ribosomal RNA was found to differ from random pattern. The observation is interpreted in terms of both the ribosomal interactions and the molecular evolution.

Base Sequence↗