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Biomedical subjects

B Kubanek

Publications and source records attributed to B Kubanek.

At least 55 records · Page 3Linked to original sources
PubMed1994

Isotype-specific immune response to a single hepatitis C virus core epitope defined by a human monoclonal antibody: diagnostic value and correlation to PCR.

In this study we tested the seroreactivity of 223 selected anti-HCV-reactive blood donors to the human B-cell epitope N-VYLLPR-C (C34-39) of the hepatitis C virus core antigen. The epitope was recently identified and characterized by the human monoclonal IgG antibody Ul/F10 and is located within the amino acid residues 34-39 of the aminoterminal core region. The blood donor sera were selected from anti-HCV ELISA (Ortho, 2nd generation)-reactive samples. Sixty-seven of these sera were further reactive in RIBA (Ortho, 2nd generation). According to their RIBA pattern, these samples were divided into four groups. Samples in the first group (n = 18) reacted to all four recombinant HCV antigens. The samples of the second (n = 9) and third group (n = 8) reacted to c22-3/c33c and c22-3/c100-3, respectively. Sera from group 4 (n = 32) showed a RIBA indeterminate pattern with reactivity only to c22-3. All 223 samples were analyzed for anti-C34-39 antibodies by ELISA, and the 67 RIBA-reactive samples were additionally tested for the presence of HCV RNA by RT/PCR. In groups 1 and 2, over 80% of the samples showed anti-C34-39 reactivity which was restricted to the IgG1 isotype. In contrast, in groups 3 and 4, antibodies to the epitope C34-39 were detected in less than 10% of the samples. Interestingly, the anti-C34-39 response correlates with the presence of HCV RNA; 95.5% of the samples had coincident results in all subgroups. None of the RIBA-negative sera showed a specific seroreaction to the C34-39 peptide.

Antibodies, Monoclonal↗
PubMed1994

Analysing the sequence diversity of the 5' NC-region of HCV-isolates found in southern Germany.

In this study we compared the nucleotide sequence of the 5' NC-region of the HCV genome isolated from seven patients and two blood donors from Southern Germany. We could identify two very distinct groups of isolates: the first very similar to the HCV prototype sequence (HCV1) with homology ranging from 99.5% to 98.7%; the second showing 91.7% homology to the HCV1. Group 1 isolates could be found in five patients and the two blood donors. Group 2 isolates could be found in the two other patients. Finally, we could observe neither nucleotide insertion nor deletion in the isolates described here.

Base Sequence↗
PubMed1994

Serum erythropoietin and serum transferrin receptor levels in aplastic anaemia.

Serum erythropoietin (EPO) and soluble transferrin receptor levels were serially measured in 74 patients with aplastic anaemia (AA). As control groups we investigated healthy controls (n = 24) and patients with iron-deficiency (n = 23) or haemolytic anaemia (n = 16). There was a significant negative correlation of log EPO on haematocrit both in AA patients and in the anaemic control group. However, for the same degree of anaemia, log EPO levels in AA were significantly higher than in iron-deficiency or haemolytic anaemia. EPO levels at diagnosis did not correlate with severity of aplastic anaemia, nor did they predict outcome after immunosuppression. During immunosuppressive treatment of AA with anti-thymocyte globulin and cyclosporine A, EPO levels were significantly lower compared with pre-treatment values without a corresponding change in haematocrit. This impaired EPO response to anaemia during immunosuppression might affect recovery of erythropoiesis. In AA patients, EPO levels declined with haemopoietic recovery. However, compared with normal controls, EPO levels in remission patients were still higher with respect to their haematocrit. Results of this study argue against the model of a simple feedback regulation of EPO via hypoxic anaemia. Our data support the hypothesis that cytokines and the erythropoietic progenitor pool are involved in the regulation of EPO production. The results illustrate that serial measurements of EPO along with therapeutic interventions are necessary to identify patients who might benefit from treatment with exogenous recombinant human EPO.

Adolescent↗
PubMed1994

In vitro platelet function during storage in three different additive solutions.

Three different synthetic media without glucose were studied for platelet storage. The first medium contained acetate and gluconate. The second contained acetate, gluconate and citrate. Finally the third contained phosphate and mannitol. The purpose of the study was to investigate whether there were differences among the various media in terms of preservation of platelet quality. Pools of platelet concentrates were prepared from buffy coats. In vitro function and metabolic parameters were measured during 5 days of storage in these additive solutions as well as in plasma. Platelet aggregation, hypotonic shock response and release of beta-thromboglobulin, platelet factor 4 and lactate dehydrogenase of the cytosol were equivalent in the media containing acetate compared to plasma storage. In vitro platelet functions and pH in these two media were better preserved compared to the medium with phosphate and mannitol. In addition bacteriological studies using platelets suspended in additive solutions or in plasma were carried out. Carryover of 20% of plasma to the synthetic media necessary for successful platelet storage in these additive solutions allows bacteriological growth. As shown, inoculation of 1 colony/ml Staphylococcus epidermidis leads to 10(6)-10(7) organisms/ml after 5 days of storage.

Blood Donors↗
PubMed1994

[Erythropoietin].

The production of red cells can be stimulated by pharmacologic doses of recombinant human erythropoietin (rHu-EPO), provided EPO-sensitive precursors and iron are available. Its side effects are negligible when used in patients with nonrenal anemia. Antibodies against rHu EPO are a rare event. Iron supplementation is routinely necessary in patients with low iron stores, since availability of iron is a rate-limiting cofactor for red cell production. The rationale for treating patients with anemia of cancer or chronic inflammation is to avoid homologous blood transfusion. However, it is not proven whether a raising of the hemoglobin concentration by 2 or 3 g% will improve the quality of life in these multimorbid patients who undergo palliative treatment. There is no evidence yet that rHu-EPO has reduced morbidity and mortality in such patients. Another question is the cost effectiveness of EPO particularly in patients who suffer from an incurable disease. EPO has also been used as an adjuvant in autologous preoperative transfusion programs and has increased the available volume of red cells for transfusion particularly in conjunction with intravenous iron supplementation. EPO given for 14 days preoperatively in patients with elective hip replacement reduced the need for transfusion by nearly 50%. A high dose of oral ferrous sulfate (300 mg) was given 11 days in advance of rHu EPO. Randomized trials are needed for patients with an initial low Hb (< 13.5 g/dl) to study the efficacy and cost effectiveness of different strategies avoiding homologous transfusion and also the risk-benefit ratio of such strategies versus homologous transfusions, since the risk of homologous transfusions has decreased considerably in recent years.

Anemia↗
PubMed1994

[HIV retrospective study of the German Red Cross blood donation service in Germany].

OBJECTIVE: It was tried to retrospectively identify HIV infections in recipients of transfusions from donors who were tested HIV positive at a subsequent donation. These lookback data were traced back to answer the following questions: 1. How many transfusion recipients were infected before the start of the routine HIV testing in 1985? 2. How great is the risk of HIV infections from infected but not yet HIV antibody-positive donors? 3. Furthermore, the transfusion of HIV-infected transfusion recipients was traced back to the involved donor to establish causality. DESIGN: Retrospective ('lookback') study. SETTING: HIV Study Group of the Red Cross Blood Banks of the Federal Republic of Germany. PARTICIPANTS: Preceding donations of HIV antibody-positive repeat donors were traced back to the transfusion recipients in order to establish their HIV antibody status. In a second lookback study, HIV-infected transfusion recipients and their corresponding donors were investigated after they had been reported to the blood bank as infected by transfusion-associated HIV. INTERVENTIONS: None. RESULTS: Recipients of 156 respectively 133 transfusions from repeat donors found to be Western blot-positive were investigated from 1985 to 1987 and from 1987 to 1992, respectively. About 50% of the recipients had died. About 40% of the recipients could not be examined, because they either were not available for testing or refused to be tested or because it was impossible to clarify the fate of the blood products. 25 HIV recipients were identified from 1981 to 1985, when routine HIV testing began. Nine transfusion-associated HIV infections were identified from 1985 to 1992. 25 million units of blood were prepared during this period. CONCLUSIONS: The risk of HIV transmission by tested transfusions is extremely rare (in the order of 1:1 million). The second lookback study suggests that in more than 50% of the blood recipients in whom HIV infection was attributed to transfusion, a causal relationship to an infected donor could not be established.

AIDS Serodiagnosis↗
PubMed1994

The autonomous release of erythropoietic inhibition during long-term in vivo administration of actinomycin D.

In this study, we describe the effect of actinomycin D (Act D), 120 micrograms/kg every 2 days, on hematopoiesis over a 48-day period. Erythropoiesis is almost totally eradicated by day 6. Despite continued Act D treatment, however, the block in differentiation between the early (burst-forming units-erythroid [BFU-E]) and late (colony-forming units-erythroid [CFU-E]) erythropoietic progenitor populations is overcome, giving rise to a synchronized and periodic erythrocytosis in both bone marrow and spleen. The first peak is seen on day 27, followed by a second peak on day 41. Circulating erythropoietin (Epo) levels increase from days 16 to 34, indicating that Act D does not have an effect on Epo production. Increasing endogenous Epo levels by bleeding results in an earlier erythroblast and 59Fe incorporation peak than in unbled animals. The BFU-E population increased in number until the block between BFU-E and CFU-E was overcome. No apparent change occurred in either the day 8 colony-forming units-spleen (CFU-S day 8) or granulocyte-macrophage colony-forming cells (GM-CFC) in the bone marrow, although a dramatic increase in GM-CFC in the spleen was observed. It appears that release from the Act D-induced block in differentiation may, in part, be due to Epo, but the mechanism by which this phenomenon takes place is unclear.

Animals↗
PubMed1994

Method dependency of blood group determination after bone marrow transplantation.

After minor-incompatible bone marrow transplantation (e.g. recipient A, donor 0), red cells are donor-type but absorb recipient-type AB0 substance from plasma. Because of discrepant results, we tested how such cells type with standard methods. In the tube test 7 of 8 patients showed donor type. In Diamed AB0 gel, weak-positive reactions were found with anti-AB in the patients (donor 0) tested. Commercial AB0 antibodies from different companies used in Diamed neutral gel trays differed widely in the results obtained. The strongest positive reactions were found with polyclonal anti-AB. The exact antibody and technique are crucial to the result of AB0 typing after minor-incompatible bone marrow transplantation.

ABO Blood-Group System↗
PubMed1994

[Occurrence of D category VI in blood donors in Baden-Württemberg].

33,830 repeated donors and 9,157 first donors were screened for DVI. All D-positive first donors and the repeated donors with depressed D antigen (Du) were tested with Seraclone anti-D (IgM) that is known to be nonreactive with DIV. D-positive donors who were negative with Seraclone anti-D were further evaluated with a monoclonal IgG anti-D nonreactive with DIV. By using a D-screen panel it was attempted to type donors who were also negative with these antibodies. With this procedure, among 42,987 donors, 4 donors with DVI and 2 donors with probable DVI or closely related variants were detected. This is in agreement with previous reports from Great Britain and Australia. These donors with qualitative variants represent 2% of donors previously typed as Du and 10% of D-positive donors who were negative with Seraclone.

Antibodies, Monoclonal↗
PubMed1994

[Leukocyte transfusion as therapy of recurrent CML after allogenic bone marrow transplantation].

Eight patients with relapsed chronic myelogenous leukemia (CML) after allogeneic bone marrow transplantation (BMT) were treated with alpha-interferon and leukocyte transfusions of the bone marrow donor. Six patients responded with disappearance of leukemic cells (Ph1, BCR-ABL) and reestablished donor hemopoiesis. All six patients developed bone marrow hypoplasia and graft-versus-host disease (GvHD). Three of the six patients died of cerebral bleeding, infection and GvHD, respectively. The remaining three patients are alive and well at day 418, 677, 818 after leukocyte transfusions. Two patients relapsed with more advanced disease of CML after BMT and failed treatment. Donor leukocyte transfusions provide an effective therapy for patients with relapsed CML after BMT, but are associated with a high mortality due to bone marrow hypoplasia and GvHD.

Antigens, CD↗
PubMed1993

Prevalence of HCV-RNA-positive blood donors and correlation to ELISA and RIBA status.

In Germany, transmission of hepatitis C virus by blood transfusion is prevented by screening the donations for anti-HCV and ALT. The specificity of the anti-HCV screening in low seroprevalence populations has been questioned. In order to evaluate this screening policy we wanted to estimate the prevalence of viremic and potentially infectious donors by the HCV-RNA polymerase chain reaction (PCR) in our donor population of southern Germany. Donors (n = 301) were divided into four subgroups according to anti-HCV status and ALT levels. HCV sequences were detected by nested PCR, using primers for the most conserved region of the viral genome. The recombinant immunoblot assay (RIBA-4) was applied to the same samples. PCR detected 4.2% HCV-RNA carriers in the subgroup anti-HCV-/ALT-; 3% in the subgroup anti-HCV-/ALT+; 19.4% in the subgroup anti-HCV+/ALT-; and 59.4% in the subgroup anti-HCV+/ALT+. It was concluded that, on the one hand, the lack of specificity of the anti-HCV ELISA gives rise to many false-positive results; on the other hand, a minority of infected donations will not be detected by the screening procedure. ALT in conjunction with anti-HCV improves the quality of screening for potentially infectious donors.

Blood Donors↗
PubMed1993

[Recent data on HIV epidemiology in Germany].

In a multicenter study on HIV prevalence the German Red Cross Blood Banks provide information on the safety of blood products and the epidemiology of HIV infections in blood donors in the FRG. Although statistically not yet significant, there are trends to an increasing number of HIV infections especially in young male blood donors. Beside an increasing number of heterosexually transmitted infections, in recent years more donors found to be infected admitted homosexual contacts. Obviously, the awareness of HIV risks is poor. The data suggest that there may be a spread of HIV infections in the general population. As the risk of HIV infection can no longer be regarded to be limited to the known risk groups, an increasing effort to educate people on HIV risks is necessary not only in blood donors but even more in the general population. The epidemiologic trends result from parts of the donor population. Aware of these trends, donor selection has been intensified by the blood banks and resulted in changes to more donations from low-prevalence populations. Therefore, the residual risk of an HIV infection by blood products can still be considered as 1:300,000 to 1:3 million in the FRG.

Blood Banks↗