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Biomedical subjects

M Frey-Wettstein

Publications and source records attributed to M Frey-Wettstein.

At least 19 recordsLinked to original sources
PubMed1997

In-process cell counts during preparation of platelet concentrates from buffy coats.

To ensure the quality of platelet concentrates (PCs), we studied in-process recoveries of blood cell counts in pooled PCs derived from four or five buffy coats (BCs) from Biopack Compoflex Systems in Bern (PC-BC/4 or PC-BC/5) and from five BCs from Optipac (Baxter) in Zurich (PC-BC/5). BCs were pooled employing a sterile connecting device and flushing them with 300 mL of platelet additive solution. The pools were centrifuged for 12 min at 500 g at 20 degrees C and filtered with PALL's Auto-Stop BC-leukocyte removal filter. Automated platelet counting was performed on whole blood donation, on single BC, on pooled BC and in the final product. Four out of 10 PC-BC/4 (= 40%) and 29 out of 30 PC-BC/5 (= 97%) had a total platelet count of > 200 x 10(9) platelets. Average percentage recoveries in PC compared to the pre-centrifugation BC pools were similar with the Biopack Compoflex and the Optipac systems, 62% and 57% respectively, whereby the absolute platelet count per one donation was similar, i.e. 49.5 x 10(9), 55 x 10(9) and 53 x 10(9) in PC-BC/4 and PC-BC/5 from Bern and PC-BC/5 from Zurich. There was a significant positive correlation between the inital number of BCs taken for pooling and the final platelet counts in the PCs. In order to recover a minimal platelet content of 200 x 10(9) platelets per pooled unit, it is safer to start out with five rather than with four donations unless recoveries during the production steps can be improved.

Blood Cell Count↗
PubMed1995

[The extent of transfusion-associated HIV infections in Switzerland until 1994: an updated estimate].

OBJECTIVE: The first report on transfusion-associated HIV infections was published in the USA in 1982. The first case reports in Switzerland were published in 1986. So far there has never been a methodologically sound answer to the question of how many persons were infected with HIV by receiving transfusions in Switzerland before the introduction of universal HIV blood donor screening. METHODS: The following available data sources were analyzed simultaneously: firstly, the results of the look-back study conducted in 1993, secondly, the reports of HIV infections and AIDS cases in the national surveillance system, and, thirdly, the claims for compensation for HIV-infected transfusion recipients and hemophiliacs. Two methodologically different and independent estimates were obtained. Firstly, the coverage of the look-back study was estimated, which made it possible to calculate the total number of documentable transfusion-associated HIV infections in Switzerland. Secondly, matching was performed on the cases in the look-back study and the reports in the national surveillance system. Applying formulas of capture-recapture designs provided a second estimate of the total number of documentable transfusion-associated HIV infections. The claims for compensation were used to corroborate the estimates obtained. RESULTS: The two methods produced almost identical figures which were corroborated by the number of claims for compensation. It is therefore estimated that 80 to 100 persons in Switzerland may have been diagnosed as having HIV infection because of transfusions in Switzerland in the years after 1980. The last five known infections occurred in 1986 (four) and, after termination of the look-back study, in 1994 (one). However, the estimate of 80 to 100 does not include individuals who were infected before 1986 and died soon--within weeks or a few months--after the transfusion without diagnosis of HIV infection being possible. CONCLUSION: This estimate of the total number of transfusion-associated HIV infections in Switzerland is approximately half earlier published ones. In addition, the present study will probably reduce the remaining uncertainties about the size of these iatrogenic HIV infections in the 1980s.

Blood Component Transfusion↗
PubMed1995

[Significance of hepatitis C virus antibodies in asymptomatic blood donors].

The aim of the study was to determine the frequency and course of hepatitis C viremia in clinically healthy, anti-HCV positive test subjects, and to ascertain whether the HCV antibodies of the IgM type differed between viremia and immunity. In 21 anti-HCV positive blood donors (test subjects) with normal transaminase activity, two serum samples, taken at an interval of 25 +/- 10 months, have been investigated for HCV-RNA and HCV-IgM antibodies. In a total of 16 test subjects (76%) HCV-RNA was found during the first test and/or the follow-up: 14 of them were positive on both occasions, and one test subject each was HCV-RNA positive exclusively at the first test and the follow-up respectively. At the time of the follow-up the serum transaminase level was elevated in 4 test subjects. 3 of these 4 were HCV-RNA positive also. On the other hand, the results of the HCV-PCR were nonuniform in HCV-IgM antibody negative test subjects. The above results demonstrate that in the majority of clinically healthy, anti-HCV positive test subjects with normal transaminase activity, a viremia exists which persists and the course of which may include inflammatory phases. The proof of HCV-IgM antibodies correlates with a viremia. On the other hand, the lack of HCV-IgM antibodies does not exclude viremia.

Adult↗
PubMed1992

[Positive direct antiglobulin test (DAGT) using the gel system].

In the gel test system the direct antiglobulin test (DAGT) shows a considerably higher sensitivity than in the tube test. Some 40% of gel test positive DAGTs prove to be negative when tested in the tube system. Most of the (auto-)antibodies detected by gel test DAGT appear to be bound integrally to the patient's own red cells and therefore are of questionable importance in view of future blood transfusions. The high sensitivity of the gel test DAGT certainly is of interest but implicates unwanted additional work for the immune hematological laboratory.

Agglutinins↗
PubMed1991

[Transfusion-associated HIV infections in Switzerland 1982-1989].

Up to summer 1987, 19 patients who had acquired HIV infection by blood transfusion had been recorded in Switzerland. In the subsequent period, up to 1989, a further 15 patients with transfusion-associated HIV infection were recorded. In December 1989, 7 of these patients were asymptomatic, 4 had ARC, 5 Aids and 11 had died of Aids. One patient died of another disease and no detailed records were available in 6. It is estimated that some 170 persons may have been infected with HIV by transfusion in Switzerland before anti-HIV testing was introduced in fall 1985. Of these only 31% (20%) are recorded today. The average incubation time from infection to diagnosis of Aids was 54 months. The 11 patients who died of Aids had mean survival of 57 months after diagnosis of the disease. In 6 instances HIV-infected blood recipients have transmitted the disease to their sexual partners.

AIDS Serodiagnosis↗
PubMed1990

[Blood component therapy after conversion to erythrocyte concentrate with added solutions].

Increased national quality requirements for blood products have led to the replacement of the conventional double-bag system with CPDA-1 anticoagulant by a 4-bag system with additive solution, buffy-coat free. Simultaneously the production of fresh blood was stopped for logistical reasons. Acceptance and possible drawbacks of these important changes in blood supply were analyzed in a postmarketing surveillance study involving some 30 hospitals. Generally the imposed changes have found good acceptance. No major problems have been recorded with regard to transfusion technique, albumin replacement, bleeding tendency etc. Pediatric stations experienced some difficulties with low protein levels in exchange transfusion. Some hospitals did regret the disappearance of fresh blood, but its replacement by the combination of red blood cells, fresh frozen plasma and platelet concentrates was well accepted.

Blood Component Removal↗
PubMed1989

[Transfusion-associated HIV infection].

In this paper an attempt is made to characterize different phases of HIV exposition by blood transfusion. In Europe, most transfusion associated (TA) HIV-infections have occurred between 1982, when AIDS started to spread and 1985, when Anti-HIV-testing was introduced in blood transfusion services. Figures of TA HIV infection in Switzerland are presented and the attitude regarding retrospective programs in this country is discussed. The present risk to contract TA HIV infection is evaluated and compared to other risks of daily life. Measures to reduce the danger of TA transmission of infections diseases are discussed.

Blood Transfusion↗
PubMed1988

[HIV transmission via blood transfusions: a study by the Swiss Red Cross blood bank service].

An inquiry amongst blood transfusion services served to establish at 19 the number of known transfusion associated HIV infections in Switzerland. In 12 cases the transfusion of an anti-HIV positive blood unit could be proven retrospectively, while in 7 cases an HIV-infected blood donor could not be found but the association of the infection with blood transfusion is highly probable by exclusion of other risk factors. All these infections occurred before introduction of anti-HIV screening in Switzerland in November 1985. After this date no new transfusion associated HIV infections have been reported. It is estimated that there are fewer than 170 transfusion associated HIV infections in Switzerland. The probability of infection with AIDS by blood transfusion is less than 1:500,000. Blood transfusion today appears to be as safe as before the emergence of the AIDS epidemic.

Acquired Immunodeficiency Syndrome↗
PubMed1986

[Post-transfusion hepatitis in the Zürich region].

In the years 1979 to 1983 approximately 350,000 units of blood were transfused in the area of Zurich. During the same period 45 cases of posttransfusion hepatitis were reported. In 12 of these cases transfusion could be excluded as cause of the hepatitis. In another 26 cases it was not possible to prove a connection between the blood transfusion and the hepatitis. Only in 7 cases was blood transfusion proved to be responsible for posttransfusion hepatitis: in 3 cases blood positive for HBs-Ag was transfused. In 3 other cases donors who had donated HBs-Ag negative blood developed hepatitis-B shortly after their blood donation: it is assumed that their blood at the time of donation was carrying infectious hepatitis-B-virus particles at a concentration too small to be detected by routine HBs-Ag screening. In one case only was transmission of non-A-non-B-hepatitis virus suspected. Due to improved HBs-Ag-screening, the incidence of posttransfusion hepatitis has been reduced by nearly 70% during the last 10 years. Nevertheless, efforts must continue to reduce the incidence of this important transfusion complication.

Blood Donors↗
PubMed1986

[Transfusion-associated LAV/HTLV-III infections in Switzerland. Report of 2 cases].

Two patients developed signs of LAV/HTLV-III infection one and two years respectively after a blood transfusion. The leading symptom in one patient was generalized lymphadenopathy, while the other patient presented with Candida stomatitis. In both cases, blood transfusions administered in 1983 were found to be the only possible source of infection; one blood donor of each patient was anti-LAV/HTLV-III positive. Family members and sexual partners of the two were negative for antibodies against LAV/HTLV-III. Our findings document the first two cases of LAV/HTLV-III associated disease most probably related to blood transfusions in Switzerland.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Blood units for patients with irregular blood group antibodies: frequency and supply.

Blood banks face significant problems supplying blood units compatible with erythrocyte antigens other than ABO and rhesus D. In this study the number of such units was evaluated between 1973 and 1982, and it was found that 1.5% of the total number of blood units were compatible with other antigens than ABO and rhesus D. Based on data of the number of units requested for each such antigen and the frequency of the antigen in the European population, a logistical system providing sufficient numbers of 'antibody-compatible' blood units is proposed.

ABO Blood-Group System↗
PubMed1983

[Use of fresh frozen plasma in a Swiss hospital district].

The causes of a unexpected rise in the consumption of fresh frozen plasma (FFP) in the years 1977-1980 are analyzed. FFP appears to be used increasingly in the department of surgery, and more specifically cardiac surgery, in the University Hospital. No basic changes are registered regarding the type of operations performed or the indications for prescribing FFP. At the same time, consumption of FFP in nonspecialized regional hospitals has increased to only a minor extent. It is pointed out that FFP is collected from blood donations and, as a product of human origin, should be used with moderation.

Blood Preservation↗
PubMed1982

[Hepatitis B virus epidemiology: degree of contamination and hyperreactors].

152 anti-HBs positive blood donors were observed for 2 to 9 years for persistence of this hepatitis-B marker. The results suggest an average persistence of anti-HBs-positive findings in the controlled carriers of at least 10 years. Some of the investigated blood donors belong to a special group of "hyperreactors" with long-lasting persistence of high-titred anti-HBs. These are apparently persons with a special immune reaction pattern.

Adult↗