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Biomedical subjects

J A Barbara

Publications and source records attributed to J A Barbara.

At least 127 records · Page 7Linked to original sources
PubMed1984

Viral infections transmitted by blood and its products.

Modern transfusion practice is associated with an increased risk of transmitting viral agents because of the changing nature of the patients and of the therapeutic blood products. More immunosuppressed patients are receiving blood released faster and with more elaborate blood components. In addition to the classically recognized importance of hepatitis B virus (itself disseminated most efficiently by contamination of products derived from large pools of plasma containing many donations) other agents are assuming increasing importance. They frequently display one or more of the predisposing characteristics of prolonged viraemia, inapparent infections and a carrier or latent state. Some of these infections like cytomegalovirus and the human T-cell leukaemia virus are transmitted only by the cellular component of blood. Others like B and non-A, non-B hepatitis and the putative agent(s) of the newly recognized acquired immune deficiency syndrome can also be transmitted in the plasma or its products. Not all the agents transmitted cause severe illness, however; human parvovirus appears to cause no clinical illness when transmitted by transfusion and infections with non-A, non-B hepatitis are largely detected only by elevations in transaminase levels. Screening tests for the presence of these agents in donor blood or for evidence of infection by them in donors continue to be studied. Other approaches, related in particular to the selection of donors, are becoming increasingly important where serological screening tests are not available.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Surveys of rubella antibodies in young adults and children.

22 000 serum samples from university students and young adult blood donors collected between 1969 and 1980 were tested for antibody to rubella virus. Of the women born in 1956 and after (i.e., those eligible for rubella vaccine at school) the proportions seronegative ranged from 3% to 6% in different years, compared with 12-20% in men of the same age groups. Serum samples from schoolchildren were also tested: 40-50% of girls and boys aged 10-11 years were seronegative--percentages similar to those before the introduction of vaccine. However, only 2-6% of 15-year-old girls (who would have been offered vaccine) were seronegative compared with 20-30% of 15-year-old boys. These results indicate that the rubella vaccination programme in the U.K. is having a significant impact on the immunological status of young women of childbearing age but that a large number of women remain potentially susceptible.

Adolescent↗
PubMed1981

Contrasting patterns and frequency of antibodies to the surface, core, and e antigens of hepatitis B virus in blood donors and in homosexual patients.

An attempt was made to assess the significance of the relatively frequent low-titre positive reactions in radioimmunoassays for antibody to hepatitis B surface antigen. Serum specimens negative for surface antigen were assayed for antibodies to the surface, core, and e antigens of the Hepatitis B virus. Two populations were studied - one of low hepatitis B incidence (2000 blood donors) and one of high incidence (200 male patients attending a clinic for sexually transmitted diseases). The validity of some singly occurring low-titre anti-HBs and anti-HBc reactions is questioned, and the occurrence of positive reactions unrelated to previous hepatitis B infection inferred.

Antibodies, Viral↗
PubMed1980

A sensitive immunoradiometric assay for the detection of hepatitis B surface antigen.

A solid-phase immunoradiometric assay for hepatitis B surface antigen is described which has been in use since 1971. Initially it was used for reference laboratory work, but from 1974 it has also been used for screening blood and blood products. Methods for the production of reagents and their use in blood transfusion and reference work are outlined.

Blood Donors↗
PubMed1980

Screening blood donors for high titre antibody to herpes varicella-zoster.

As a method of increasing supplies of varicella-zoster immunoglobulin, semi-automated screening of blood donors for high titre complement-fixing antibody was initiated. This was compared with the previously used method of donor selection based on a history of varicella or zoster in the past 6 months. About one-third of the "history" donors had titres of greater than or equal to 1 in 64 and generally these levels declined rapidly. In contrast, although only 1.1% of donors in random screening had antibody titres greater than or equal to 1 in 64, these levels usually remained high during repeated donation, enabling the production of pools entirely composed of high titre plasma packs.

Antibodies, Viral↗
PubMed1979

Effect of rubella vaccination programme on serological status of young adults in United Kingdom.

Antibody to rubella virus was measured in over 10,000 serum samples collected in 1976, 1977, and 1978 from young adult blood donors and university students. The incidence of seronegatives was lower (4--7%) among females born in 1956 and subsequently--i.e., among the age groups offered rubella vaccine at school--than among females born before 1654 (11--20%). The incidence of seronegatives among males in the 1977 and 1978 surveys had the opposite trend, with a higher proportion of seronegatives in younger males, born in 1956 and subsequently, than in older males. The findings provide evidence that the rubella vaccination programme in the U.K. is having a significant impact on the immunological status of young females of childbearing age. Nevertheless too high a proportion of young females remains potentially susceptible to rubella.

Adolescent↗
PubMed1979

A sensitive single reverse passive haemagglutination test for detecting both HBsAg and anti-HBs.

A trial of a modified reverse passive haemagglutination test for HBsAg using a 0.1% cell suspension instead of the recommended 1% showed an approximately eight-fold increase in detection sensitivity. The test can be performed within 30 minutes and lends itself to mass screening techniques. Confirmation tests can be done using the 0.1% method. In addition, the same serological plates and cells used for HBsAg screening can then be used to screen for high-titre anti-HBs. This makes the overall screening for both HBsAg and high-titre anti-HBs donors cheap and convenient.

Antibodies, Viral↗
PubMed1978

Liver enzyme concentrations as measure of possible infectivity in chronic asymptomatic carriers of hepatitis B.

Fifty-two British-born blood donors who were chronic carriers of hepatitis B surface antigen (HBsAg) were tested for the presence of hepatitis B e antigen (HBeAg) and antibody to HBeAg by an immunoradiometric assay. The presence of HBeAg was closely associated with a slight rise in serum liver enzyme concentrations, a high HBsAg titre, and male sex. We suggest that the finding of persistently raised serum liver enzyme concentrations in an asymptomatic HBsAg carrier might be useful as a likely indicator of HBeAg and high infectivity.

Carrier State↗
PubMed1977

A comparison of different methods of screening blood donations for HBsAg.

In a retrospective comparison between countermigration immunoelectrophoresis (CIEP) and reverse passive haemagglutination (RPHA) for screening 260,500 blood donations, the latter's 10-fold increase in sensitivity resulted in 36% more HBsAg detections. In a prospective comparison between RPHA and radioimmunoassay (RIA) the latter's 40-fold increase in sensitivity over RPHA resulted in 11% more detections than RPHA in 27,094 new donors. One in 500 new donors was HBsAg-positive by RPHA, compared with 1 in 11,000 established donors who had donated and been tested previously. Acute hepatitis B infections, though uncommon, accounted for a greater proportion of the HBsAg-positive found in "established" rather than new donors. Reported post-transfusion hepatitis cases have declined following the introduction of screening tests in 1971. The feasibility of RIA testing at a transfusion centre supplied simply with the two basic RIA reagents has been demonstrated.

Blood Donors↗