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Biomedical subjects

W Weimar

Publications and source records attributed to W Weimar.

At least 253 records · Page 14Linked to original sources
PubMed1990

[Possibilities and limitations of heterotopic auxiliary liver transplantation].

Although auxiliary heterotopic liver transplantation offers theoretical advantages over orthotopic liver replacement, clinical results have heretofore been dismal. After development of a technique of reduced size liver grafts provided with portal and arterial blood and venous drainage via the suprahepatic V. cava (HLT) in experimental animals, this method was applied in 21 transplantations in 19 patients. 11 of 16 patients with chronic liver insufficiency and one of three patients with fulminant liver failure survived transplantation for at least 1 year. HLT was well tolerated even by high-risk patients. Possibilities and limitations of this novel approach are discussed.

Adult↗
PubMed1990

Rejection prophylaxis with sequential OKT3 and CSA after kidney transplantation.

Sixteen kidney transplant recipients received the IgG2a anti-CD3 monoclonal antibody OKT3 and azathioprine as rejection prophylaxis during the first two postoperative weeks. Concomitant immunosuppression consisted of low dose steroids while cyclosporine A therapy was instituted on day 12. Side effects included fever, bronchospasm, hypotension and diarrhoea. OKT3 caused T cell modulation resulting in CD3 dim+, CD4+ or CD8+, CD5+, WT31- and 11F2- cells. Anti-OKT3 antibodies were found in approximately 50% of the patients. The protocol induced a 100% patient and graft survival and a 81% actuarial freedom of rejection at 18 months. It prevented CsA associated nephrotoxicity in the direct postoperative phase. These beneficial effects outweighed the side effects of OKT3.

Adult↗
PubMed1990

gamma delta T-cell receptor-positive T-cell clones derived from human heart transplants do not show donor-specific cytotoxicity.

gamma delta T-cell receptor-positive T-cell clones were obtained from three endomyocardial biopsies taken from two patients. Clones obtained from two biopsies from patient A, one taken during rejection and one after resolution of this rejection, were WT31-, 11F2+, Ti gamma A-, delta TcS1+. Clones from patient B grown from a biopsy without histologic signs of rejection were either WT31-, 11F2+, Ti gamma A+, delta TcS1-, or WT31+. All gamma delta T-cell receptor-positive clones had cytolytic potential but did not demonstrate donor-specific lysis.

Biopsy↗
PubMed1990

Comparison of four different cyclosporine immunoassays in heart and kidney transplant recipients.

Four different immunoassays were used to measure cyclosporine A (CsA) plasma (20 degrees C) levels in heart and kidney transplant recipients. Two radioimmunoassays (RIAs) (Sandimmune and Cyclotrac) and the fluorescence polarization immunoassay (FPIA) were based on polyclonal antibodies, whereas the fourth (Cyclotrac-SP) used a CsA-specific mouse monoclonal antibody. We found considerable differences in measured CsA concentrations, which were dependent on the method used and the clinical situation of the patient. Correlation coefficients between the nonspecific assays ranged from 0.899 to 0.901 with plasma values increasing in the order Sandimmune less than Cyclotrac less than FPIA. In the CsA-specific RIA, values were lower, and the correlation with the nonspecific assays ranged from 0.761 to 0.795. In the first 21 days posttransplantation, the heart transplant group showed a higher ratio of nonspecific/specific CsA (mean 4.0) compared with the subsequent period (mean 2.3) or with renal transplant recipients (mean 2.4). The TDX method showed the best assay characteristics. In heart transplant patients with specific and nonspecific 125I-RIA methods, mean CsA levels were 25% lower during rejection periods compared with periods without signs of rejection.

Antibodies, Monoclonal↗
PubMed1990

Effect of immunomodulator thymopentin on impaired seroresponse to influenza vaccine in patients on haemodialysis.

In a double-blind placebo-controlled multicentre study, the effect of the immunomodulator thymopentin (TP5) on the antibody production to trivalent influenza vaccine was tested in 108 patients on chronic intermittent haemodialysis (HD). Antibody production was determined in pre- and postvaccination sera. Compared to a group of 35 young healthy adult control subjects, HD patients showed a clearly impaired seroresponsiveness to all three vaccine components, regardless of treatment with TP5 or placebo. We conclude that TP5 administration is not able to enhance humoral immunity in patients on chronic intermittent HD.

Adolescent↗
PubMed1990

Cytomegalovirus seronegative heart transplant recipients. Prophylactic use of anti-CMV immunoglobulin.

Thirty-two CMV seronegative heart transplant patients received prophylactic anti-CMV immunoglobulin during the first three posttransplant months. One of the 16 recipients of a heart from a seronegative donor acquired CMV infection and developed CMV disease. In eight of the 16 recipients of a heart from a seropositive donor, CMV infection was observed. Viremia was diagnosed in seven of them, but only two of these patients developed CMV disease. The incidence of CMV infection and of CMV disease in the globulin-treated CMV seronegative recipients of a heart from a seropositive donor was comparable to the incidence of CMV infection and of CMV disease in 31 nonglobulin-treated CMV seropositive recipients. This was significantly lower (percentage difference 69 percent, 95 percent CI 42-97 percent, p less than 0.001) than expected on the basis of the data from the literature and indicates that passive immunization with anti-CMV immunoglobulins induces the same protection against CMV disease as natural acquired anti-CMV resistance. This protective effect was temporary, as one patient developed symptomatic CMV infection four months after transplantation at a time when the anti-CMV immunoglobulin levels had decreased to pretransplantation values.

Cytomegalovirus↗
PubMed1990

Quality control of anti human CD3 and CD4 monoclonal antibodies.

By testing two monoclonal antibodies (MoAb), we tried out two methods, which might be suitable for quality control of anti human T cell MoAb. RIV6 and RIV9 were investigated by flow cytometry and Enzyme-linked Immunosorbent Assay (ELISA). The characteristics, specificity and biological activity of RIV6 and RIV 9 were determined and compared respectively with other CD4 specific MoAb, OKT4, OKT4a, LEU3a and the CD3 specific MoAb OKT3 and LEU4 by flow cytometry. An ELISA was set up to quantify mouse IgG3 antibody. Specificity, plate variability and day to day effects were determined. The results illustrate that ELISA and flow cytometry are valuable tools in the quality control of these antibodies.

Animals↗
PubMed1989

Effect of one-HLA-DR-antigen-matched and completely HLA-DR-mismatched blood transfusions on survival of heart and kidney allografts.

Blood transfusions can influence the survival of organ allografts favorably, in spite of the danger of sensitization. We investigated the influence of HLA compatibility between blood donors and transfusion recipients on the production of HLA antibodies and on graft survival. Among recipients of transfusions who shared one HLA-DR antigen with their respective donors, antibodies developed in 6 of 28 who had received one transfusion, in 2 of 16 who had received three transfusions, and in 4 of 24 who had undergone renal transplantation. Among recipients who were mismatched with their donors for both HLA-DR antigens, the rate of sensitization was significantly higher in all three of these groups (18 of 30, P = 0.02; 12 of 16, P = 0.0007; and 12 of 22, P = 0.001). The survival of kidney allografts among graft recipients who were given transfusions and shared one HLA-DR antigen with their blood donors (81 percent at five years) was significantly higher than among recipients who were given transfusions and were mismatched for both HLA-DR antigens (57 percent; P = 0.02) or among recipients who were not given transfusions (45 percent; P = 0.001). There was no difference in graft survival between patients who received transfusions mismatched for two HLA-DR antigens and those who were not given transfusions. We conclude that allograft survival can be improved by pretransplantation blood transfusion when the transfusion recipients share at least one HLA-DR antigen with their donors. In view of the increased rate of sensitization and the lack of improvement in graft survival, the transfusion of blood mismatched for two HLA-DR antigens appears to be contraindicated in candidates for transplantation.

Antibody Formation↗
PubMed1989

Changes in immunological parameters after conversion from cyclosporine A to azathioprine in renal transplant recipients.

Long term CsA therapy did not interfere with the basal levels of natural killer (NK) activity in stable cadaveric renal transplant recipients. However, 3 months after changing immunosuppressive therapy from CsA to AZA, NK activity was significantly decreased (36 +/- 25% vs 19 +/- 15%, P less than 0.01). Following in vitro exposure to IFN-gamma an increase in NK activity from 36 to 44% (P less than 0.05) could be induced during CsA therapy but this was no longer observed after conversion to AZA (19 to 22%, N.S.). A prominent decline in the number of NK cells expressing the surface receptor for the Fc portion of IgG was also found postconversion. The IFN-gamma production capacity after mitogen stimulation of unprimed lymphocytes was more depressed during CsA than during AZA therapy (median 25 vs 80 U/ml 10(6) cells, P less than 0.05), suggesting a reversible inhibition of CsA on lymphokine production. Despite the better IFN-gamma production capacity, both the activity, inducibility and number of NK cells were significantly lower under AZA therapy than under CsA therapy. These findings indicate that CsA exerts its immunosuppressive action without an important interference with NK activity. Monitoring mononuclear cells showed a decrease in absolute numbers of all phenotypically distinct cells studied after conversion. The prominent decrease in CD 8 cells resulted in an increase of CD 4/CD 8 ratio.

Azathioprine↗
PubMed1989

Cytomegalovirus infection and renal transplantation.

Cytomegalovirus (CMV) infections remain a major clinical problem after renal transplantation. Reported incidences of CMV disease range from 17 to 25% in patients with azathioprine treatment and from 2 to 23% in patients on cyclosporin A. CMV-related death occurs in 1-3% of the total kidney transplant population. CMV seronegative kidney recipients of a transplant from a seropositive donor are especially at risk for primary infection as CMV can be transmitted by the transplant. In patients treated with antilymphocyte globulin (ALG) preparations for rejection, CMV disease is diagnosed three to four times more frequent than in patients without ALG therapy. Prevention of CMV infection is possible by selecting CMV seronegative donors for seronegative recipients. Active and passive immunization does not prevent CMV infection after renal transplantation, but immunoprophylaxis may result in less severe CMV disease. Effective treatment of clinical overt CMV disease is possible with the new guanine analogue ganciclovir. However, the use of this drug is associated with neutropenia, especially in patients with compromised kidney function. More pharmacokinetic data are needed to determine optimal dosing schemes.

Acyclovir↗
PubMed1989

Prevention of cytomegalovirus-related death by passive immunization. A double-blind placebo-controlled study in kidney transplant recipients treated for rejection.

In a double-blind placebo-controlled study, the value of prophylactic anti-CMV immunoglobulin administration was evaluated in 39 kidney transplant recipients treated for rejection with rabbit antithymocyte globulin. Passive immunization completely prevented CMV-related death, although it did not reduce the incidence of CMV isolation, viremia, or disease. The effect of passive immunization was exclusively observed in CMV-seronegative recipients of a CMV-seropositive kidney donor. It could be demonstrated even when instituted when antirejection therapy was started. Seropositive recipients did not benefit from immunoglobulin treatment. Moreover, CMV-seronegative recipients of a kidney from a seronegative donor were not at risk for CMV infection at all. Therefore passive immunization should be restricted to seronegative recipients of seropositive allograft donors treated for rejection.

Antibodies, Viral↗