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Biomedical subjects

B Kubanek

Publications and source records attributed to B Kubanek.

At least 19 recordsLinked to original sources
PubMed2002

Erythropoiesis and performance after two weeks of living high and training low in well trained triathletes.

The purpose of our study was to evaluate hematologic acclimatization during 2 weeks of intensive normoxic training with regeneration at moderate altitude (living high-training low, LHTL) and its effects on sea-level performance in well trained athletes compared to another group of equally trained athletes under control conditions (living low - training low, CONTROL). Twenty-one triathletes were ascribed either to LHTL (n = 11; age: 23.0 +/- 4.3 yrs; VO 2 max: 62.5 +/- 9.7 [ml x min -1 x kg -1]) living at 1956 m of altitude or to CONTROL (n = 10; age: 18.7 +/- 5.6 yrs; VO 2 max: 60.5 +/- 6.7 ml x min -1 x kg -1) living at 800 m. Both groups performed an equal training schedule at 800 m. VO 2 max, endurance performance, erythropoietin in serum, hemoglobin mass (Hb tot, CO-rebreathing method) and hematological quantities were measured. A tendency to improved performance in LHTL after the camp was not significant (p < 0.07). Erythropoietin concentration increased temporarily in LHTL (Delta 14.3 +/- 8.7 mU x ml -1; p < 0.012). Hb tot remained unchanged in LHTL whereas was slightly decreased from 12.5 +/- 1.3 to 11.9 +/- 1.3g x kg -1 in CONTROL (p < 0.01). As the reticulocyte number tended to higher values in LHTL than in CONTROL, it seems that a moderate stimulation of erythropoiesis during regeneration at altitude served as a compensation for an exercise-induced destruction of red cells.

Acclimatization↗
PubMed2001

Efficient retrovirus-mediated transduction of primitive human peripheral blood progenitor cells in stroma-free suspension culture.

Retroviral transduction of hematopoietic cells has resulted in unsatisfactory gene marking in clinical studies. Since cytokine-stimulated stem cells have engrafted poorly in animal models, we investigated phenotypic changes during culture of peripheral blood progenitor cells (PBPC). Human CD34(+) HLA-DR(low) cells, immunomagnetically separated from PBPC collections, were found to extrude rhodamine-123, which is characteristic for primitive hematopoietic cells. Cells were grown in suspension cultures supplemented with cytokines. While interleukin-3-containing factor combinations promoted cell proliferation they caused loss of rhodamine-123 extrusion and reduced the frequencies of cobblestone area-forming cells (CAFC). Several other cytokines failed to stimulate cell divisions, which are required for retroviral transduction. A combination including Flt-3 ligand (FL), interleukin-6 and stem cell factor (SCF) preserved an immature phenotype for 5 to 6 days and stimulated cell divisions, which was improved upon addition of leukemia inhibitory factor and interleukin-11. Furthermore, the CAFC frequency among cells treated with these cytokines was increased as compared with widely used cocktails containing interleukin-3, interleukin-6 and SCF. Rhodamine-123 appeared to be a particularly sensitive indicator for differentiation of PBPC. For analysis of gene transfer, amphotropic retroviruses conferring an MDR1 cDNA were added repeatedly for 6 days to cytokine-treated PBPC stroma-free cultures. Proviral cDNA was detected by polymerase chain reaction in 68% of cobblestone areas derived from CD34(+)HLA-DR(low) cells that had been exposed to Flt-3 ligand, interleukin-6 and SCF. In summary, conditions were identified that facilitate efficient transduction of early PBPC with amphotropic retroviruses while preserving a primitive phenotype for extended periods.

Antigens, CD34↗
PubMed2000

Transplant activities in Germany in 1998--a survey facilitated by the National Registry for Hemopoietic Stem Cell Transplantation.

To improve the infrastructure of hemopoietic stem-cell transplantations in our country, the German Registry for Hemopoietic Stem-Cell Transplantations (DRST) was established in 1998. The present paper summarizes the current status of the DRST and gives a survey of transplant activities in Germany in 1998 in terms of transplant units, transplant types, transplant frequencies and underlying diseases.

Blood Cells↗
PubMed2000

Palliative cytoreduction in refractory acute leukemia: a retrospective study of 57 adult patients.

The efficiency and toxicity of treatment regimens for nonintensive cytoreduction in 57 outpatients with refractory acute leukemia (mean age 56 years, 51 AML, six ALL/AUL) were retrospectively studied. Seventeen patients received one treatment regimen, 19 patients two treatment regimens, and 21 patients three or more treatment regimens. The treatment regimens analyzed were 6-thioguanine p.o. (daily) (T), 6-thioguanine p.o. (4-7 days/week) + cytarabine s.c./i.v. (once a week) (T+C), 6-mercaptopurine p.o. (daily) (MP), 6-mercaptopurine p.o. (daily) + methotrexate p.o./i.v. (once a week) (MP+MTX), etoposide p.o. (daily) (E), and mitoxantrone i.v. (M). The median leukocyte count was higher for M (73 x 10(9)/l) than for the other treatment regimens (T: 27 x 10(9)/l, T+ C: 37 x 10(9)/l, MP: 24 x 10(9)/l, MP + MTX: 30 x 10(9)/l, E: 31 x 10(9)/l). A cytoreduction >50% in the peripheral blood was achieved by T in 11/19, by T+C in 7/11, by MP in 5/8, by MP+MTX in 3/6, by E in 3/4, and by M in 16/22 patients. The period of cytoreduction was regarded as the duration of response - T: median 53 days, range 5-98; T+C: median 61 days, range 14-226; MP: median 37 days, range 4-192; MP + MTX: median 58 days, range 36-59; E: median 121 days, range 26-159; M: median 39 days, range 8-78. T and T + C were well tolerated by all but three patients (stomatitis, diarrhea, WHO grade 2). MP was accompanied by a rise of transaminases (WHO 1-3) in 5/6 patients. E led to stomatitis (WHO 1,2) in 4/5 and M to nausea/vomiting (WHO 1,2) in 5/22 and to stomatitis (WHO 2) in 4/22 cases. The mean survival time after start of palliative cytoreduction was 16 weeks (2-65). In summary, 6-thioguanine +/- cytarabine was best tolerated with effective but in oral monotherapy - often protracted cytoreduction in 60% of patients. Mitoxantrone showed tolerable side effects and potent cytoreduction in 73% of patients even after ineffective palliative pretreatment. Palliative cytoreductive therapy does not reduce the quality of life and can prevent complications of significant leukocytosis in refractory acute leukemia.

Acute Disease↗
PubMed2000

Practices and attitudes towards quality assurance, inspection and accreditation in blood collection establishments in the European community.

In the framework of a European Community (EC)-supported project, a survey of practices and attitudes towards quality assurance, inspection and accreditation in Blood Collection Establishments (BCEs) in the EC member states was carried out. Analysis of 352 responses to a structured questionnaire revealed a preference for national standards over international, and an introspective and reactive view to quality management. Four broad categories of operational performance in relation to safety were formed: initial, repeatable, managed and optimising, with the majority of responses (209) being characterized as initial. Although a direct relationship between the size of the BCE and the range and level of quality management practices is apparent in the data, further analysis shows that small BCEs have much higher ratio of personnel per blood unit collected/processed than large BCEs and thus seem to have an inherent potential for improvement. Overall, a clear preference for inspection and accreditation by professional peers at the national level was indicated.

Accreditation↗
PubMed2000

Serum erythropoietin and thrombopoietin levels in patients with essential thrombocythaemia.

In 40 patients with essential thrombocythaemia (ET) serum erythropoietin (EPO) and thrombopoietin (TPO) concentrations were determined and compared with the EPO and TPO values of a healthy control group. The mean EPO serum concentration for 24 control patients was 9.4 mU/ml +/- 3.7 (range 2-17.9), for 32 untreated ET patients at diagnosis 6.6 mU/ml +/- 7.6 (range 0.5-44.3) and for 8 ET patients treated with cytoreduction 14.1 mU/ml +/- 8.0 (range 4.5-26.1). Serum EPO levels in untreated ET patients at diagnosis were significantly lower compared with serum EPO levels in healthy control patients (p=0.002). Serum EPO levels in treated ET patients were not different from serum EPO levels in healthy controls (p=0.13) but were significantly higher compared with untreated ET patients (p=0.003). Serum TPO levels were determined in 18 of 40 ET patients, the mean TPO serum concentration was 211 pg/ml +/- 109 (range 62,5-345). The mean TPO serum concentration for 10 untreated ET patients at diagnosis was 162 pg/ml +/- 87 (range 62,5-302) and for 8 ET patients who had received cytoreductive treatment 272 pg/ml +/- 106 (range 96-345), respectively (p=0.04). Both serum TPO levels for treated and untreated ET patients were significantly higher (p<0.001) compared with serum TPO levels for healthy controls. The results of our study suggest a difference in the regulation of serum EPO and TPO in patients with ET. While the mean serum EPO level is decreased in untreated ET patients, the corresponding mean serum TPO level is increased. Treatment with cytoreduction, results in normalisation of the mean serum EPO level, whereas the mean TPO serum level remains elevated.

Adolescent↗
PubMed1999

Experiences in HCV-NAT screening prior to releasing cellular components by the German Red Cross Blood Transfusion Service of Baden-Württemberg.

In this report we present the accumulated data on nucleic acid testing (NAT) for hepatitis C virus (HCV) RNA of blood donations by the Blood Transfusion Service of Baden-Württemberg in the period between March 1997 and March 1999. An extra barcoded blood sample was collected from each donor. Samples were tested by NAT in mini-pools of maximally 96 samples. First-time and repeat donors were tested separately. RT/HCV-PCR was performed with the COBAS HCV Amplicortrade mark, versions 1.0 and 2.0 from Roche Diagnostic Systems. Many modifications have been introduced to the original protocol since the implementation of NAT screening aiming at an increase in the sensitivity and specificity of the assay. NAT positive pools containing serologically positive samples were detected. Initially, reactive pools were identified that could not be confirmed by secondary pooling and single testing procedures. So far, no serologically negative but NAT positive sample has been found.

Blood Banks↗
PubMed1999

An ELISA specific for murine erythropoietin.

Murine recombinant erythropoietin (EPO) was purified from an EPO-producing cell line and used for the production of polyclonal monospecific anti-murine EPO antibodies in rabbits. The anti-mouse EPO antibodies were purified by two affinity chromatography procedures. In order to obtain the most sensitive ELISA, different antibody combinations were tested in the ELISA sandwich assay. The best combination was achieved with an anti-human EPO antibody as coating and the biotinylated anti-murine EPO antibody as detecting antibody. With this sandwich-ELISA a sensitive standard curve in the range of 0.6-30 mU/ml could be established. The assay provides a sensitive and reliable measure of murine EPO in serum and cell culture supernatants ranging from normal to highly elevated EPO levels.

Animals↗
PubMed1999

Comparison of T-cell-depleted BMT and PBPCT with respect to chimerism, graft rejection, and leukemic relapse.

Chimerism analysis by DNA-based methods is a valuable diagnostic tool for monitoring engraftment and leukemic relapse after allogeneic BMT or PBPC transplantation (PBPCT). We investigated the chimerism after T-cell-depleted BMT (n = 32) in comparison with T-cell-depleted PBPCT (n = 39). BM grafts were T-cell depleted using the Campath-IgM antibody plus complement. For T-cell depletion of the PBPC grafts, a selection of CD34+ cells with or without a subsequent CD2/3 depletion was performed. In all patients, the T-cell dose of the transplant was < 10(6)/kg body weight. Between day 13 and day 120 after transplantation, chimerism analysis was done by RFLP or amplified fragment length polymorphism (PCR-AFLP), with a detection limit of 1%-5% recipient cells. In the BMT group, 8 of 32 (25%) patients showed a mixed chimerism, but only one graft rejection and no leukemic relapse occurred after a median follow-up of 41 (3-84) months. All patients with PBPCT revealed a complete chimerism of their granulocytes, and 38 of 39 patients showed complete chimerism of their lymphocytes. Follow-up time in these patients is 7 (2-21) months, with no graft rejection and two leukemic relapses. G-CSF-mobilized PBPC are superior to BM cells for full engraftment even after T-cell-depleted transplantation. The more relevant factor for developing complete chimerism seems to be the quantity and possibly the quality of the stem cells rather than the residual T-cell load of the graft. However, a mixed chimerism of the lymphocytes early after transplantation does not predict a higher rate of graft rejection or leukemic relapse.

Adult↗
PubMed1998

Thrombopoietin serum levels in patients with aplastic anaemia: correlation with platelet count and persistent elevation in remission.

In an attempt to evaluate the role of thrombopoietin (TPO) in the pathobiology of aplastic anaemia (AA), we have examined TPO levels in sera from 54 AA patients and 119 healthy controls. A total of 92 samples were collected from AA patients: 43 samples were harvested at diagnosis, 23 samples in the cytopenic period after treatment, and 26 samples when patients were in partial (n=10) or complete remission (n=16) following immunosuppressive treatment. TPO serum levels were assessed by a sandwich-antibody ELISA that utilized a polyclonal rabbit antiserum for both capture and signal. Serum samples from normal donors revealed a mean TPO level of 95.3 +/- 54.0 pg/ml (standard deviation). Mean TPO levels in AA sera collected at diagnosis and before onset of treatment were 2728 +/- 1074 pg/ml (P<0.001 compared to normal controls: mean platelet count at that time: 27x10(9)/l). TPO serum levels of AA patients in partial or complete remission after immunosuppressive treatment were significantly lower than TPO levels at diagnosis (P<0.001). However, despite normal platelet counts (mean 167x10(9)/l), TPO levels remained significantly elevated in complete remission (mean TPO 1009 +/- 590 pg/ml, P<0.001 compared to normal controls). There was a significant inverse correlation between serum TPO levels and platelet counts in AA patients who were not transfused for at least 2 weeks prior to sample collection (coefficient of correlation (r) = -0.70, P<0.0001). In summary, TPO levels were highly elevated in sera of patients with AA. Thus there is no evidence to suggest an impaired TPO response contributing to thrombocytopenia in AA. Thrombopoietin did not return to normal levels in remission, indicating a persisting haemopoietic defect in remission of AA. We hypothesize that elevated levels of TPO may be required to maintain normal or near normal platelet counts in remission of AA.

Adolescent↗
PubMed1998

Mini-pool screening by nucleic acid testing for hepatitis B virus, hepatitis C virus, and HIV: preliminary results.

BACKGROUND: The purpose of this study was to evaluate the feasibility of nucleic acid testing (NAT) of mini-pools as a blood donation screening test. STUDY DESIGN AND METHODS: The stepwise implementation of NAT of mini-pools began in January 1997. Since March 1997, all blood donations collected by the German Red Cross Blood Transfusion Service of Baden-Württemberg were tested for hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV nucleic acids. An extra barcoded serum sample is collected from each blood donor for NAT-based screening, which is performed only on hepatitis B surface antigen-, anti-HCV-, anti-HIV-, and anti-Treponema pallidum-seronegative donations. Samples are pooled to a maximum of 96. Positive results are resolved through intersecting subpools (a chessboard design). NAT-based screening does not include a virus concentration step before nucleic acid extraction. RESULTS: By the end of October 1997, 331, 783 donations in 3,779 pools had been screened. As yet, no viremic but seronegative blood donor has been found for the three markers. CONCLUSION: It is feasible to incorporate NAT-based screening of mini-pools into the routine virus diagnostics of a large blood transfusion service. It remains to be determined whether screening blood donations by NAT will indeed increase the safety of blood supply.

Blood Donors↗
PubMed1998

Blood transfusion: influence of transfusion therapy on outcome.

Few studies have addressed the influence of different transfusion therapies on outcome in a convincing way. Proven adverse impact of allogeneic blood on outcome is minimal. Acute mortality has declined to about 1 : 500,000 and the rate of transfusion-transmitted infections is decreasing, too. Data on postoperative infections and non-Hodgkin's lymphoma as possible adverse effects are controversial. Evidence for an increased risk of tumour recurrences is lacking. Alternatives to allogeneic blood may have appreciable risks: perioperative blood recovery had a fatality rate of more than 1 : 40,000. Reduction of allogeneic blood exposure may not be equated with improved outcome.

Journal Article↗
PubMed1998

Isolation and characterization of human monoclonal antibodies against hepatitis C virus envelope glycoproteins.

The isolation and characterization of human monoclonal antibodies (humAbs) against the hepatitis C Virus (HCV) glycoproteins E1 and E2 are described. B-cells from blood donors with anti-HCV were transformed with Epstein-Barr virus. The supernatants of the resulting lymphoblastoid clones were screened by ELISA with an extract of cells infected with a recombinant vaccinia virus RMPA95 expressing the envelope proteins E1 and E2 of an HCV genotype 1a virus (H strain). Positive clones were fused to the heteromyeloma cell line K6H6/B5. Fifteen heterohybridoma cell lines have been established. The specificity of the isolated humAbs was determined both by ELISA and Western blot assays. Several recombinant extracts expressing either the E1 or E2 protein or truncated forms were used in an attempt to map the epitopes on the viral glycoproteins. Some of the humAbs were used successfully for immunofluorescence investigation of transfected cells. Seven specific anti-E2 humAbs, which react with the envelope protein 2 of genotype 1a and 1b isolates, were characterized.

Animals↗
PubMed1998

Estimated risk of transmission of hepatitis C virus by blood transfusion.

OBJECTIVE: The risk of transmitting hepatitis C (HCV) by transfusion of anti-HCV-negative screened blood was estimated for the blood donor population of Baden-Württemberg (southwestern Germany). METHODS: The data from the blood donors screened for anti-HCV and for HBsAg during 1990-1995 were analyzed. RESULTS: The prevalence of confirmed anti-HCV -positive blood donations decreased continuously during the last 5 years, reaching 121 per 100,000 blood donations. A higher anti-HCV prevalence rate was found in female than in male blood donors (p < 0.05). The estimated risk of transmitting HCV during the window period is 1:200,000 (1:97,000-1:1,400,000) for repeat donors. In 1995, the calculated risk for first-time donors was 1:20,000 (1:15,000-28,000). The incidence for HCV was 1.2 per 100,000 blood donations. CONCLUSION: The risk of transmitting hepatitis C by blood transfusion is low. Additional tests to shorten the window period to detect antibodies to HCV might increase the safety of blood transfusion.

Blood Donors↗
PubMed1998

Mobilization and collection of allogeneic peripheral blood progenitor cells for transplantation.

A median dose of 11 (6-17) microg G-CSF per kg and day was given to 96 (49 female, 47 male) healthy family donors in order to mobilize and to collect peripheral blood progenitor cells (PBPC) for allogeneic transplantation. Donor age was 36 (17-76) years. The leukocytes of the donors increased to 46 (12-115) x 10(9)/l on days 4-6 of G-CSF treatment with a median of 71 (2-657) CD34+ cells per microl, respectively. Female and older donors seem to have a lower response to G-CSF. About 32% of the donors suffered from side-effects of G-CSF requiring analgetics. A total of 197 stem cell aphereses were performed using the COBE Spectra cell separator. Median apheresis time was 225 (118-300) min processing 11.8 (5.7-20) l blood, collecting 5.3 (1.7-14.9) x 10(10) nucleated cells and containing 0.7 (0.1-3.7)% CD34+ cells. Severe citrate toxicity occurred in 5% of the donors. Retransfusion of autologous platelets post apheresis was necessary in 16% of the donors because of a platelet count <80 x 10(9)/l. An insufficient number of stem cells was collected in four female donors due to a very poor response to G-CSF. In conclusion, the collection of allogeneic G-CSF-mobilized PBPC is safe and effective. One or two aphereses were sufficient in 91% of the donors to achieve >4 x 10(6) CD34+ cells per kg. In 4% of the donors an additional bone marrow harvest or the use of an alternative donor was necessary because of a poor mobilization.

Adolescent↗