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Biomedical subjects

B Kubanek

Publications and source records attributed to B Kubanek.

At least 37 records · Page 2Linked to original sources
PubMed1997

Anti-HCV envelope prevalence in blood donors from Baden-Württemberg.

We assess the diagnostic value of the recombinant antigens E1/E2 (heterodimer) and E2 for the screening of blood donors. For this purpose an ELISA assay was developed which used these recombinant glycoproteins as solid antigens on the microtiter plates. The anti-E1/E2 assay was able to detect 80% of the positive samples by Matrix and 87% of the PCR-positive samples. Anti-E2 was less sensitive. Fifteen percent of the indeterminate samples were anti-E1/E2 and 8% anti-E2 positive. In the case of the indeterminate samples there was no coincidence of results between these assays and the PCR. Fifty percent of seroconverters showed an anti-E1/E2-positive result with a previous indeterminate donation. We conclude that the recombinant envelope proteins, mainly anti-E1/E2, might be used in future in the diagnostics of HCV infection to increase the sensitivity of the currently used assays.

Blood Donors↗
PubMed1997

After-effects of a high altitude expedition on blood.

The aim of the study was to investigate blood alterations caused by altitude acclimatization which last more than few days after return and might play a role for exercise performance at sea level. Measurements were performed in 12 mountaineers before, during and either 7/8 or 11/12 days after a Himalaya expedition (26-29 days at 4900 to 7600 m altitude). [Erythropoietin] rose only temporarily at altitude (max. +11 +/- 1 [SE] mu/ml serum). After return hemoglobin mass (initially 881 +/- 44 g, CO-Hb method) was increased by 14% (p < 0.01); aspartate aminotransferase activity in erythrocytes (initially 682 +/- 25 U/l) was augmented (day 7: +964 +/- 152 U/l, day 11: +533 +/- 107 U/l) indicating reduced mean cell age. Calculated blood volume (+14%) was influenced by red cell formation at altitude but also by plasma expansion at sea level. The half saturation pressure for Hb-O2 (pH 7.4, 37 degrees C) as well as the 2.3-diphosphoglycerate concentration were already initially high (32.1 +/- 0.5 mmHg, 20.5 +/- 0.7 mumol/g Hb) and showed only a nonsignificant tendency to increase after return. Also Hill's n was consistently high in the mountaineers, whereas the Bohr coefficients were slightly increased only after descent. Probably the preparatory physical training, partly in the Alps, and the stay in the Himalaya influenced O2-affinity for a prolonged time. The adaptations might reduce the loss of physical performance capacity at altitude and be part of altitude training effects.

Acid-Base Equilibrium↗
PubMed1997

Haematopoietic reconstitution after autologous transplantation of CD34(+)-selected versus non-selected peripheral blood progenitor cells.

Selection of CD34+ cells for autologous transplantation is increasingly being used to reduce potential tumor cell contamination of the autograft. Haematopoietic reconstitution in 40 patients after transplantation of CD34(+)-selected versus non-selected G-CSF-mobilized PBPC was compared and was almost identical in the two groups of patients. Delayed platelet engraftment was only observed in patients transplanted with a CD34+ cell dose of < 2.5 x 10(6)/kg body weight. It has to be shown whether the positive selection of CD34+ cells will improve the disease free survival after autologous PBPC transplantation.

Adolescent↗
PubMed1997

[Study by the Professional Organization of German Transfusion Physicians on epidemiology of HIV- and hepatitis infections in blood donors].

The frequency of the seromarkers of HIV, HCV, and HBV in the donor population from all donor centers in Germany became available from the multicenter study of the transfusion services. From these data the risk of virus transmission by blood products can be estimated at 1:1 million for HIV and 1:50,000 for HBV. For HCV, preliminary data indicate the risk for Germany in less than 1:20,000. The risk is even lower, with less than 1:200,000 when calculated from seroconversion data of a rural donor population. The safety of blood products has been very much improved due to the continuous donor selection over the last years and by the epidemiologic situation in Germany.

Blood Donors↗
PubMed1996

[Fatal Yersinia infection after intraoperative transfusion].

A 47-year old man was operated for a malignant tumour of the bladder. During cystectomia packed red cells had to be transfused. Minutes after the rapid transfusion the oxygen saturation dropped. In the following hours his circulation became unstable and the pulmonary function deteriorated. Signs of disseminated intravascular coagulation occurred, making more transfusions necessary. Inspite of all intensive-care efforts the patient died with a multiorgan failure caused by endotoxin shock 66 hours after having received the first transfusions. In the blood cultures of the patient and in the cultures of the first transfused unit of packed red cells Yersinia enterocolitica was isolated.

Bacteremia↗
PubMed1996

Combined CD34 positive plus CD2 negative selection for effective T-cell depletion as GvHD-prophylaxis in HLA-nonidentical blood progenitor cell transplantation.

G-CSF mobilized, T-cell-depleted peripheral blood progenitor cells (PBPC) and T-cell-depleted bone marrow (BM) were given to seven children (6 AL, 1 SCID) to prevent severe graft-versus-host-disease (GvHD) as well as graft rejection after transplantation from HLA-nonidentical parental donors. BM was T-cell-depleted by lectin agglutination and E-rosetting. For T-cell-depletion of the PBPC grafts a combination of CD34+ selection with the Ceprate SC immunoadsorption system and a subsequent depletion of CD2+ cells with immunomagnetic Dynabeads was used. The overall recovery was 0.3 (0.1-1.2)% for nucleated cells, 29 (18-45)% for CD3+ cells, respectively. The purity of CD34+ cells was 87 (68-97)% with a 0.3(0.05-0.7)% residual CD3+ T-cell contamination. In spite of the large T-cell number in the PBPC grafts the combination of CD34 positive and subsequent CD2 negative selection achieved a more than 4 log T-cell depletion and prevents severe GvHD even in HLA-nonidentical transplantation. In addition, if a high dose of progenitor cells ensures stable engraftment, this new approach could increase the possibility of wider use of HLA-mismatched family donors for transplantation.

Adult↗
PubMed1996

Improved lectin agglutination method for T-cell depletion of HLA-mismatched bone marrow grafts in children.

For T-cell depletion in HLA-nonidentical bone marrow transplantation of children with malignant diseases, we improved the original lectin/rosetting method described in 1981 by adding anti-CD2/3 coated donor red blood cells to the combination to achieve lectin agglutination in one step. Further improvements in handling led to a shortened and simplified method and better quality of the graft. Five bone marrow grafts prepared with this modified protocol contained a median number of 6 (0-28) x 10(4) T-cells per kg, corresponding to 0.02 (0-0.08)% CD3+ cells and 6 (3.7-10.5) x 10(6) CD34+ cells per kg at a median body-weight of 7 (5-38)kg. The overall recoveries after T-cell depletion were: NC 17 (10-44)%, CD34+ cells 61 (22-100)%, and CFU-GM 55 (29-212)%.

Agglutination↗
PubMed1996

HCV transmission through blood transfusion: are HCV-RNA titer in donor serum and genotype major determinants of infection outcome?

In this paper we report the results of a retrospective investigation on anti-HCV supplemental test positive blood donors from 1993 and 1994. 22 living recipients of blood/blood components from 15 donors were localized and enrolled in the study. Serum from these individuals were tested by serological assays and RT/PCR. HCV-RNA titer was determined for all positive donors. Genotyping was performed for all HCV-RNA positive individuals (donors and recipients). We observed that less than 50% of the recipients of previous donations from those positive donors did develop serological markers of HCV infection. HCV-RNA titers in donor's serum varied from 2 x 10(3) to 5 x 10(5) copies/ml but a direct correlation between viral RNA titer and the outcome of infection could not be established. Genotype investigation revealed 100% identity of genotypes within the pairs of donors/recipients. Genotype 1 b reached a prevalence of 75% within this group.

Blood Donors↗
PubMed1995

The serology of hepatitis C virus (HCV) infection: antibody crossreaction in the hypervariable region 1.

We determined the NS1/E2 N-terminal sequence including the hypervariable region 1 (HVR1) from five individuals chronically infected with HCV: two from the Czech Republic and three from Germany. From each sequence, six 12-mer overlapping peptides were synthesized and used in a peptide scan to evaluate seroreactivity of each of those patients, as well as three anti-HCV positive blood donors to the different isolates. We could show the general presence of antibodies to multiple HVR1 specific sequences reflecting the existence of multiple variants in infected persons. Finally, we observed the persistance of HCV infections in all individuals despite an active humoral response directed against the virus.

Base Sequence↗
PubMed1995

Autologous platelet transfusion in alloimmunized patients with acute leukemia.

Seventy-eight transfusions of autologous platelets were given to eight alloimmunized patients receiving curative chemotherapy for acute leukemia. Platelets were collected at regeneration of hematopoiesis after a chemotherapy cycle, cryopreserved with 5% dimethylsulfoxide in liquid nitrogen, and retransfused during bone marrow aplasia following the next treatment cycle. The in vitro platelet recovery after freezing, thawing, and washing was 85 +/- 4%. The in vivo corrected count increment 1 h after autologous platelet transfusions was 11 +/- 5 x 10(9)/l. With the exception of moderate urticaria and slight nausea each after one transfusion, no immediate or chronic side effects occurred. The bleeding time was shortened and hemorrhage during bone marrow aplasia was prevented in all alloimmunized patients by autologous platelet transfusions.

Acute Disease↗
PubMed1995

Human monoclonal antibodies for the immunological characterization of a highly conserved protein domain of the hepatitis C virus glycoprotein E1.

Although both envelope glycoproteins of the hepatitis C virus, E1 and E2/NS1, show a high degree of sequence variation, the E1 protein includes a well conserved domain, which may be functionally important. We have analysed the human B cell response to a peptide fragment from amino acid residues 314-330 (EP3) covering the central conserved sequence of this domain. Anti-hepatitis C virus-positive blood donors were screened for anti-EP3 antibodies with an ELISA based on immobilized peptide. Thirty out of 92 (32%) RIBA-confirmed donors displayed a significant antibody response to EP3. From three of these blood donors we established four anti-EP3-producing heterohybridoma cell lines: Ul/F30 and Ul/F31 produced IgM-kappa, whereas Ul/F32 and Ul/F33 secreted the isotypes IgG1-lambda and IgG1-kappa, respectively. Epitope analysis with overlapping nonapeptides suggests the existence of different antigenic determinants within the EP3 fragment. Although both IgG antibodies Ul/F32 and Ul/F33 have dissociation constants to the peptide of approximately 10(-9) M, binding to recombinant E1 protein expressed in COS-7 cells was different. Only Ul/F33 detected envelope protein of approximately 24-35 kD in Western blot. This human MoAb will be useful for further investigations on the hepatitis C virus glycoprotein E1.

Amino Acid Sequence↗
PubMed1995

Quality of pooled platelet concentrates prepared from buffy coats and stored in an additive solution after filtration.

Platelet concentrates prepared from buffy coat were pooled and stored for 6 days after removal of leukocytes by filtration. The platelets were stored in plasma or in an additive solution, Plasmalyte-A. In vitro platelet function was better preserved using Plasmalyte-A than plasma with regard to osmotic reversal and aggregation. No significant differences for the release of platelet markers beta-thromboglobulin, platelet factor 4, or lactate dehydrogenase pre- and post-filtration and storage in plasma or Plasmalyte-A was observed. Expression of the surface membrane glycoproteins Ib, Ia/IIa, IIb/IIIa, and IV measured by flow cytometry after binding of monoclonal antibodies did not change during storage. The expression of activation-dependent alpha-granula glycoprotein GMP140, the thrombospondin, and the glycoprotein 53 from the lysosomal granules was not different between platelet pools stored in plasma or in Plasmalyte-A. The in vitro quality of platelets stored as pools is comparable for plasma and the additive solution Plasmalyte-A.

Acetates↗