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Biomedical subjects

J A Barbara

Publications and source records attributed to J A Barbara.

At least 109 records · Page 6Linked to original sources
PubMed1989

Provision of a panel of anti-toxoplasma-negative blood donors.

Toxoplasma gondii has been reported to cause complications only in immunosuppressed patients receiving leucocyte transfusion, when severe acute toxoplasmosis has been reported with associated mortality. At the North London Blood Transfusion Centre (NLBTC) we have screened 392 plasmapheresis donors (using toxoreagent latex agglutination test manufactured by Eiken) to provide a panel of blood donors negative for antibody to toxoplasma for seronegative recipients. A toxoplasma-negative panel of donors would only be required for those rare instances when granulocyte concentrates are indicated for transfusion of seronegative recipients. The toxoreagent test classified the 392 blood donors as 36% positive, 23% weakly reactive and 41% negative; these negative sera were retested with toxoreagent and 17% of them reacted weakly but none were positive. The toxoreagent 'weakly-reactive' sera (all of which were Sabin-Feldman dye test negative) can probably best be accounted for by the exacting screening conditions under which we operated to ensure seronegativity in our special donor panel. 40% of the antibody-positive donors were female and 34% male. Seropositivity increased with age.

Adult↗
PubMed1989

Microbiological screening of blood donations: cost versus effectiveness.

The already considerable list of pre-transfusion microbial screening tests may well increase. Some American opinion favours attempting to achieve a 'zero-risk' blood supply by introducing extra tests. However, as well as being theoretically unattainable, 'zero-risk' causes practical problems as the efficacy of a screening test is often predicted, not proven. The increasing complexity of extra testing can overload the system, causing laboratory and clerical errors, and although the blood supply must be as safe as possible a small residual risk should be anticipated and balanced against the risk of withholding transfusion. Assessing cost-effectiveness requires that indirect and direct consequences of infecting a recipient are considered. What is cost-effective in one country may not be elsewhere, due to factors such as microbial prevalence. Uniformity of worldwide transfusion policy must be balanced against the best local use of increasingly limited health-care budgets.

Blood↗
PubMed1989

Gelatin particle agglutination assay for HIV antibodies: a rapid, economical modification with increased sensitivity.

Modification of a commercial gelatin particle agglutination assay for anti-HIV reduces the test time to 30 min, increases the sensitivity sevenfold without any prozoning, and maintains specificity while cutting the cost of the test by 90%. The modification involves a tenfold dilution of the gelatin particles, which are added to a dilution of test serum in a 'V' well standard microplate. After incubation, plates are centrifuged briefly and allowed to stand at an inclination of 70 degrees until positive and negative reactions are clearly distinguishable within approximately 15 min.

Agglutination Tests↗
PubMed1989

Rapid transfer of small volumes of serum into microplates.

A method has been devised to transfer small volumes of serum, as an adjunct to larger volume sampling, into microplates. The Costar Transplate 96 machine is used routinely in our laboratory for transferring serum samples into reaction wells for anti-HIV screening. Using this additional method a mean of 4 microliters of serum was transferred, within acceptable limits of error (coefficient of variation, c.v., 16%).

Agglutination Tests↗
PubMed1987

Cytomegalovirus and blood transfusion.

The problem of transfusion-transmitted cytomegalovirus (CMV) infection differs from that for other transfusion-transmitted infections in that only patients who are immunocompromised require CMV-free blood or components. The virus is cell-associated and transmission appears to be due to reactivation of latent virus in white blood cells. As a herpes virus, CMV can be responsible for primary infections, reactivations or reinfections in humans. The use of restriction endonuclease techniques is sometimes necessary to pinpoint the origin of infections. Serological studies have shown that CMV infection is worldwide, but seropositivity rates vary widely being highest in underdeveloped countries, rising both with age and lower socio-economic status. Provision of CMV seronegative blood therefore involves considerable administrative as well as laboratory effort and planning, especially if panels of previously tested, seronegative donors are organized. Serious complications of transfusion-transmitted CMV infection (which can occasionally prove fatal) are only seen with immuno-suppressed patients (commonly low birth weight infants or transplant recipients). Prevention or amelioration of CMV infection with appropriate patients can be attempted by reducing the number of white blood cells present in blood or components by filtration or washing, administration of CMV immune globulin or provision of blood found by serological screening to be CMV-seronegative.

Cytomegalovirus Infections↗
PubMed1986

AIDS: a problem for the transfusion service?

The first case of AIDS associated with blood transfusion was described in 1982. Over the following two years great advances were made in the understanding and prevention of this new hazard associated with blood transfusion, culminating in 1985 with the introduction of a screening test for blood donation.

Acquired Immunodeficiency Syndrome↗