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Biomedical subjects

F A Ala

Publications and source records attributed to F A Ala.

16 recordsLinked to original sources
PubMed1995

Hepatitis C virus seroconversion rate in established blood donors.

The results of hepatitis C virus (HCV) antibody test of 237,813 blood donations collected from 143,815 donors by the West Midlands Blood Transfusion Centre in 1993 were analyzed retrospectively in order to determine the seroconversion rate among established previously anti-HCV negative donors. Three hundred sixteen (0.22%; 1 in 455) donors were positive by the enzyme linked immunosorbent assay (ELISA) screening test and 34 (0.024%; 1 in 4,230) donors were positive by ELISA and the Recombinant Immuno Blot Assay (RIBA). Three donors previously negative for HCV antibody reacted positively by both tests. The annual seroconversion rate was calculated as one in 35,937 donors. This figure argues against limitation of HCV antibody screening to new blood donors. A further 45 donors negative on previous screening reacted positively by ELISA and were indeterminate by RIBA. Unexpectedly, lapsed blood donors first tested for HCV antibody in 1993 had high positive reaction rates by ELISA and RIBA, which was significantly (P < 0.001) higher than those of new donors. RIBA-positive reaction rate among ELISA-positive donors was significantly higher amongst males than females (P < 0.001).

Adult↗
PubMed1995

Hepatitis C virus infection in the asymptomatic British blood donor.

Blood donor screening for hepatitis C virus (HCV) antibodies is now routine. Most blood transfusion services recommend that seropositive donors are referred for further investigation. Southern European studies suggest that many asymptomatic seropositive donors have clinically significant liver disease. Seropositive donors in areas of high prevalence may not, however, be representative of British donors. We have prospectively examined the prevalence and severity of HCV infection in a British volunteer blood donor population. During a 14 month period, only 0.35% (999/287,332) of all donors in the West Midlands were anti-HCV (screening assay) positive. Only 5% (52/999) of these were confirmed true seropositive. Nearly 80% (41/52) of seropositive donors were referred to the Queen Elizabeth Hospital Liver Unit for further investigation. Most underwent complete investigation, including liver biopsy. Forty of forty-one donors had biochemical, histological, or virological evidence of persistent viral infection. Histological changes were generally mild and none was cirrhotic. Covertly infected patients had less severe disease than those with an overt risk factor for HCV exposure. In the British Midlands, the prevalence of blood donor seropositivity is low. In contrast with seropositive Southern European donors, the British donor is more likely to belong to an at-risk group for parenteral exposure and is less likely to have severe histological changes. This study highlights the importance of developing locally relevant guidelines for the counselling and investigation of anti-HCV-positive blood donors.

Adult↗
PubMed1995

Management of blood donors whose donations are repeatedly falsely positive by the HIV antibody screening test.

Since 1985, over 1,800,000 donations have been screened by the West Midlands Regional Blood Transfusion Service for antibody to HIV. Twelve regular donors gave three or more donations that were alternatingly positive and negative in the screening test, but not confirmed to be HIV positive by supplementary testing. Extensive investigation of six of these donors, including the polymerase chain reaction (PCR), failed to confirm HIV infection. The donors were reassured but, nevertheless, retired to comply with the guidelines of the National Blood Transfusion Service. These findings indicate that, for UK donors, ambiguous serological findings are unlikely to reflect HIV infection. On the rare occasions where serological results are particularly ambiguous, PCR testing of donors' blood may be helpful.

AIDS Serodiagnosis↗
PubMed1992

Guidelines for the use of fresh frozen plasma. British Committee for Standards in Haematology, Working Party of the Blood Transfusion Task Force.

Fresh frozen plasma should only be used to treat bleeding episodes or prepare patients for surgery in certain defined situations. Definite indications for the use of FFP: 1. Replacement of single coagulation factor deficiencies, where a specific or combined factor concentrate is unavailable. 2. Immediate reversal or warfarin effect. 3. Acute disseminated intravascular coagulation (DIC). 4. Thrombotic thrombocytopenic purpura (TTP). Conditional uses: FFP only indicated in the presence of bleeding and disturbed coagulation: 1. Massive transfusion. 2. Liver disease. 3. cardiopulmonary bypass surgery. 4. Special paediatric indications. No justification for the use of FFP: 1. Hypovolaemia. 2. Plasma exchange procedures. 3. 'Formula' replacement. 4. Nutritional support. 5. Treatment of immunodeficiency states.

Adult↗
PubMed1991

Polymerase chain reaction for detection of human cytomegalovirus infection in a blood donor population.

We have used the polymerase chain reaction (PCR) to analyse 420 normal donor blood samples taken at a city centre donation site. Three sets of human cytomegalovirus (HCMV) primers specific to the HXLF6, immediate early and late antigen gp64 genes, of the alpha, beta and gamma antigen coding regions respectively, were used to allow for the possibility of sequence variation. There was perfect correlation between the three sets of primers. Latex agglutination and enzyme-linked immunosorbent assay (ELISA) were also employed to provide data for a comparative study. The complete data show that infection with human cytomegalovirus is not only age related but is also sex related. The female population examined using PCR reached a peak infection rate of 80% by the age of 40-50 years whereas the male population reached a 98% infection rate following an almost linear increase with age. Latex agglutination data shows a similar picture although the infection rate peaks around 20% lower than with PCR. The data shows an increase in sensitivity using the PCR rather than the serology although the clinical significance of this has yet to be determined. The work presented here also demonstrates the suitability of the polymerase chain reaction as a potential diagnostic and epidemiological tool.

Age Factors↗
PubMed1990

Assessment of fetal-maternal haemorrhage in mothers with hereditary persistence of fetal haemoglobin.

Kleihauer examination of peripheral blood cannot be used reliably to detect transplacental fetal-maternal haemorrhage in mothers with hereditary persistence of fetal haemoglobin (HPFH). In Rh(D) negative pregnancies diagnostic confusion with a large fetal-maternal haemorrhage could result in the administration of inappropriately excessive amounts of anti-D immunoglobulin, and the inability to diagnose and quantify transplacental haemorrhage in maternal HPFH by current methods could result in insufficient anti-D administration and subsequent Rh(D) sensitisation. Accordingly, a method to detect and quantify fetal-Rh(D) positive maternal haemorrhage using erythrocyte fluorescent immunocytometry was developed. An indirect immunofluorescence method with IgG anti-D immunoglobulin as the primary antibody was used, combined with quantitative analysis on a fluorescence activated cell sorter. The method was accurate, specific, and sensitive and could detect a contaminating population of 0.1% Rh(D) positive cells in Rh(D) negative blood--a level of fetal-maternal haemorrhage well covered by a single dose of 500 IU of anti-D immunoglobulin.

Adult↗
PubMed1988

Reducing the cost of anti-HIV screening.

In an attempt to reduce the cost of testing for anti-human immunodeficiency virus (HIV) we looked at the possibility of recycling the Wellcozyme (R) HIV antigen bound wells; our findings showed that there was no significant reduction in sensitivity of the test samples or controls when run in parallel with new plates. It was concluded that the use of recycled plates was a cost effective means of performing more tests.

Acquired Immunodeficiency Syndrome↗
PubMed1985

A rapid chemiluminescent enzyme-linked immunosorbent assay for cytomegalovirus immunoglobulin G antibodies using instant photographic film.

A rapid and convenient chemiluminescent enzyme-linked immunosorbent assay (ELISA) for IgG antibodies to cytomegalovirus has been developed which uses low cost equipment. Assays were carried out on transparent microtitre plates and used an anti-human IgG horseradish peroxidase conjugate. Bound peroxidase was detected chemiluminescently using a p-iodophenol-luminol-peroxide reagent. Light emission from the wells of the microtitre plate was detected on instant photographic film (ASA 20,000) held in a specially designed shutter type camera. The semi-quantitative technique was tested in a routine laboratory for a period of 7 wk and the results obtained compared well (95.3% agreement) with those obtained by a conventional colorimetric ELISA using an alkaline phosphatase label.

Antibodies, Viral↗