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Biomedical subjects

L M Williamson

Publications and source records attributed to L M Williamson.

At least 19 recordsLinked to original sources
PubMed2005

Increase in HIV sexual risk behaviour in homosexual men in Scotland, 1996-2002: prevention failure?

OBJECTIVE: To investigate trends in homosexual men's sexual risk behaviour for HIV infection in Scotland. METHODS: Cross sectional surveys in 1996, 1999, and 2002 were carried out in "gay" bars in Glasgow and Edinburgh, Scotland. 6508 men-2276 (79% response rate) in 1996, 2498 (78%) in 1999, and 1734 (62%) in 2002. RESULTS: In 1996, 10.7% of men surveyed and in 1999, 11.2% reported unprotected anal intercourse (UAI) with casual partners, compared with 18.6% in 2002 (p < 0.001). There was also a significant increase in men reporting that they "knew" their casual partners' HIV status, despite no increase in HIV testing among men who reported UAI with casual partners. In 2002, increases in UAI with more than one partner, in UAI with casual partners and in reporting seroconcordance remained significant after adjusting for confounding factors including HIV testing status and demographic characteristics. CONCLUSIONS: High risk sexual behaviour among homosexual men in Scotland increased between 1999 and 2002. Men showed increased confidence of shared antibody status, despite no increase in HIV testing, or evidence of discussion of HIV status. Explanations for this must include consideration of a cultural shift in the perception of HIV and "prevention failure" on the part of governments and health agencies.

Adolescent↗
PubMed2004

Good in parts: the Gay Men's Task Force in Glasgow--a response to Kelly.

We know that peer education, or the use of popular opinion leaders (POLs), works in terms of reducing reported risk behaviour for HIV infection amongst gay men. The work of Jeffrey Kelly and his colleagues provides some of the best scientific evidence in support of this approach. Influenced by this work, we undertook a peer education intervention amongst gay men in bars in Glasgow--the Gay Men's Task Force (GMTF)--but failed to demonstrate any reduction in sexual risk behaviour for HIV infection. In this paper we describe why we were unable to repeat in Scotland the success in small cities in the USA of the POL model. Our explanations include: failure to replicate the 'core elements' of POL; spatial and temporal differences between the original POL settings and the bars of Glasgow; and the currency of ideas such as 'peer education' beyond the protocols designed for their implementation. However, we also describe some of the successful features of the GMTF in Glasgow, and the continued value of peer education in contributing to reductions in sexual risk behaviour for HIV infection.

HIV Infections↗
PubMed2004

Using patient-identifiable data for epidemiological research.

The use of patient-identifiable data in epidemiological research is subject to increasingly complex regulation. This article reports the experience of a research team in setting up the Epidemiology and Survival of Transfusion Recipients (EASTR) study in which patient-identifiable information was needed in order to link data from two sources for analysis and obtain long-term survival patterns of transfusion recipients. The process of establishing the study involved obtaining separate ethical, research and development and data protection approval, including application to the newly formed Patient Information Advisory Group, set up under Section 60 of the Health and Social Care Act, 2001. We describe the high cost in administrative procedures and time now necessary to gain statutory approval before such a study can begin, which has been the result of recent legislation. Issues arising from our experience are discussed.

Epidemiology↗
PubMed2004

The role of prophylactic fresh frozen plasma in decreasing blood loss and correcting coagulopathy in cardiac surgery. A systematic review.

Summary Fresh frozen plasma is commonly used in cardiac surgery in an attempt to replace clotting factors and to decrease bleeding. Despite this, there has been no previous review of the available literature to support this practice. The aim of this review was to study the effect of prophylactic peri-operative transfusion of fresh frozen plasma on bleeding and coagulopathy in patients undergoing cardiac surgery. A comprehensive literature search was performed and all randomised controlled trials of the use of fresh frozen plasma in cardiac surgery were included. Six small trials were found that included a total of 363 participants with six different dose regimens of fresh frozen plasma. The overall quality of the studies was poor due to small patient numbers and lack of allocation concealment. There was no evidence that the prophylactic use of fresh frozen plasma affected peri-operative blood loss in cardiac surgery. There was some evidence that it may improve platelet count and fibrinogen concentration.

Blood Coagulation Disorders↗
PubMed2004

Guidelines for the use of fresh-frozen plasma, cryoprecipitate and cryosupernatant.

The indications for transfusing fresh-frozen plasma (FFP), cryoprecipitate and cryosupernatant plasma are very limited. When transfused they can have unpredictable adverse effects. The risks of transmitting infection are similar to those of other blood components unless a pathogen-reduced plasma (PRP) is used. Of particular concern are allergic reactions and anaphylaxis, transfusion-related acute lung injury, and haemolysis from transfused antibodies to blood group antigens, especially A and B. FFP is not indicated in disseminated intravascular coagulation without bleeding, is only recommended as a plasma exchange medium for thrombotic thrombocytopenic purpura (for which cryosupernatant is a possible alternative), should never be used to reverse warfarin anticoagulation in the absence of severe bleeding, and has only a very limited place in prophylaxis prior to liver biopsy. When used for surgical or traumatic bleeding, FFP and cryoprecipitate doses should be guided by coagulation studies, which may include near-patient testing. FFP is not indicated to reverse vitamin K deficiency for neonates or patients in intensive care units. PRP may be used as an alternative to FFP. In the UK, PRP from countries with a low bovine spongiform encephalopathy incidence is recommended by the Departments of Health for children born after 1 January 1996. Arrangements for limited supplies of single donor PRP of non-UK origin are expected to be completed in 2004. Batched pooled commercially prepared PRP from donors in the USA (Octaplas) is licensed and available in the UK. FFP must be thawed using a technique that avoids risk of bacterial contamination. Plastic packs containing any of these plasma products are brittle in the frozen state and must be handled with care.

Adult↗
PubMed2002

The contrasting IgG-binding interactions of human and herpes simplex virus Fc receptors.

A virally encoded, high-affinity Fc receptor (FcR) is found on herpes simplex virus type 1 (HSV-1) particles and infected cells where its binding of non-immune IgG protects cells from host-mediated lysis. Whilst mutation or aglycosylation of the IgG CH2 domain reduced binding to human FcR, the interaction with HSV-1 FcR was not affected. However, the HSV-1 FcR, unlike human FcR, discriminates between human IgG1 allotypes, being sensitive to changes at positions 214 (CH1) and 356/358 (CH3), away from its proposed binding site at the CH2-CH3 interface. The biological consequences are not known but this is the first evidence of a major functional difference between IgG1 allotypes.

Antibody-Dependent Cell Cytotoxicity↗
PubMed2002

The development of a national standardized approach for the enumeration of residual leucocytes in blood components.

BACKGROUND AND OBJECTIVES: The UK Blood Transfusion Services implemented universal leucocyte depletion of the blood supply in November 1999. To provide statistical process monitoring of these processes, automated methods were introduced to count residual leucocytes (white blood cells) in blood components. MATERIALS AND METHODS: Initially in the National Blood Service (NBS) England, protocols were standardized on the use of LeucoCount reagents with either Becton-Dickinson or Beckman Coulter flow cytometers. RESULTS: Standardization of protocols resulted in a decreased intersite variability of red cell samples (from 36% to 9% at a level of 11 and 10 cells/ micro l, respectively), and 100% of sites (n = 11) fulfilled the validation criteria. However, we also evaluated the use of alternative reagents with the result that reagents from either Becton-Dickinson or Beckman Coulter, used on either a Becton-Dickinson or Beckman Coulter flow cytometer, passed our validation criteria. CONCLUSIONS: It is critical to include samples from filtered products containing white blood cells in validations of leucocyte enumeration methodology, as results may differ between methods using these samples but not using spiked or fixed material. Standardized gating strategies and optimization methods for flow cytometers are critical for obtaining equivalent results with different reagents and instruments.

Blood Banks↗
PubMed2002

Value of central analysis of leucocyte depletion quality control data within the National Blood Service, England.

BACKGROUND AND OBJECTIVES: The results of quality monitoring leucocyte counts were analysed nationally for the first 2 years of universal leucocyte depletion (LD), spanning the time-period before and after standardization of the counting and LD methods. The objectives were twofold: first to determine whether the implementation strategy was effective in achieving the LD specification (< 5 x 10(6) leucocytes in 99% of components with 95% statistical confidence); and second, whether quality monitoring was able to detect potential non-conformance. MATERIALS AND METHODS: Residual leucocytes were counted using Beckman Coulter or Becton Dickinson (BD) flow cytometers and reagents. Data were collected into standardized analysis software (NWA Quality Analyst) for local trend analysis and checks for conformance to process specification, and collated centrally. Analysis was performed for six time-periods between January 1999 and March 2001. Specification failures were analysed to determine the likelihood of extreme failure. Statistical process monitoring was adjusted to suit LD processes. RESULTS: Data from red cells in optimal additive solution (OAS), filtered either as whole blood or red cell concentrates, and platelet pools improved significantly over the 2-year period with specification failures falling from 0.35%, 0.48% and 0.56%, respectively, in January-June 1999 to 0.06%, 0.01% and 0.04% in January-March 2001. Specification failures in red cells in OAS LD for the period January-December 2000 showed only 0.02% with a leucocyte count of > 30 x 10(6)/unit. Extreme failures are now very rare. Monitoring methods have been effective in detecting process change and drift. CONCLUSION: LD performance varies between different LD systems, but monitoring has proved sufficiently robust to detect processes that perform poorly. The chosen specification has been both achievable and appropriate to the systems in use. Standardization of the counting method is central to the ability to monitor and analyse results effectively across the whole service.

Blood Banks↗
PubMed2002

Gay men's HIV testing behaviour in Scotland.

This paper reports on the social and demographic factors associated with HIV testing in gay men in Scotland. Trained sessional research staff administered a short self-complete questionnaire to men in gay bars during January and February 1999 in Glasgow and Edinburgh, Scotland. Questionnaires were completed by 2,498 men (response rate of 77.5%). Half (1,190; 50%) reported ever having been HIV antibody tested, with men in Edinburgh more likely to report testing. Testing was associated with being older (26 years plus), higher education, reporting one unprotected anal intercourse (UAI) partner, or six or more UAI partners, in the last year, genitourinary medicine clinic service use, and lifetime experience of sexually transmitted infections. There was no relationship between HIV testing and treatment optimism, or evidence of a "post-Vancouver" effect. Over a fifth of men who said that they knew their own HIV status at last UAI had never been tested. Current testing policy needs to be challenged if there is to be an increase in the number of gay men who know their HIV status and, if tested HIV-positive, to then access antiretroviral treatments.

Adolescent↗
PubMed2002

Trends in head injury mortality among 0-14 year olds in Scotland (1986-95).

STUDY OBJECTIVE: To examine the trends in childhood head injury mortality in Scotland between 1986 and 1995. DESIGN: Analysis of routine mortality data from the registrar general for Scotland. SETTING: Scotland, UK. SUBJECTS: Children aged 0-14 years. MAIN RESULTS: A total of 290 children in Scotland died as a result of a head injury between 1986 and 1995. While there was a significant decline in the head injury mortality rate, head injury as a proportion of all injury fatalities remained relatively stable. Boys, and children residing in relatively less affluent areas had the highest head injury mortality rates. Although both these groups experienced a significant decline over the study period, the mortality differences between children in deprivation categories 1-2 and 6-7 persisted among 0-9 year olds, and increased in the 10-14 years age group. Pedestrian accidents were the leading cause of mortality. CONCLUSIONS: Children residing in less affluent areas seem to be at relatively greater risk of sustaining a fatal head injury than their more affluent counterparts. While the differences between the most and least affluent have decreased overall, they have widened among 10-14 year olds. The decline in head injury mortality as a result of pedestrian accidents may be partly attributable to injury prevention measures.

Accidents, Traffic↗
PubMed2002

Does bar-based, peer-led sexual health promotion have a community-level effect amongst gay men in Scotland?

This paper evaluates the effectiveness of a bar-based, peer-led community-level intervention to promote sexual health amongst gay men. The intervention consisted of peer education within bars, gay specific genitourinary medicine (GUM) services and a free-phone hotline. Data were collected at baseline (1996) and at follow-up (1999) in gay bars in Glasgow (intervention city) and Edinburgh (control city). During the intervention peer educators interacted with 1484 men and new clients increased at the gay specific GUM service. However, the hotline was under-utilized and abused. The outcome measures were: reported hepatitis B vaccination; HIV testing; unprotected anal intercourse (UAI) with casual partners; negotiated safety; and amongst men reporting UAI with a regular partner, the proportion who knew their own and their partner's HIV status. Significant differences in sexual health behaviours were observed across locations and across time, but the only significant intervention effects were amongst men who had direct contact with the intervention, with higher uptake of hepatitis B vaccination and HIV testing. The intervention did not produce community-wide changes in sexual health behaviours. These results question the replication and transferability of peer-led, community-level sexual health promotion for gay men outwith the USA and across time.

Adolescent↗
PubMed2001

The effect of leucocyte depletion on the quality of fresh-frozen plasma.

The aim of this study was to evaluate the quality of leucodepleted (LD) fresh-frozen plasma (FFP) produced using one of five whole blood filters (Baxter RS2000 & RZ2000, NPBI T2926, Macopharma LST1 and Terumo WBSP) or two plasma filters (Pall LPS1 and Baxter FGR7014). Whole blood or plasma was filtered within 8 h of collection at an ambient temperature. Samples were taken pre- and post filtration for analysis of coagulation factors and complement activation (n = 7--12 for each type of filter). All filtered units (209--286 ml) contained < 5 x 10(6) residual leucocytes and < 30 x 10(9)/l platelets. Statistically significant losses of factors V, VIII, IX, XI and XII and increases in markers of coagulation activation were observed (0--21%), which were dependent on filter type. None of the filters had a significant effect on von Willebrand factor (VWF) multimeric distribution or the activity of VWF and factors II, VII or X. The effect on levels of C3a appeared to be related to the filter surface charge: positively charged filters resulted in C3a generation, whereas negatively charged resulted in C3a removal. None of the observed changes are likely to be clinically significant unless subsequent processing of plasma (such as pathogen inactivation) results in further losses of coagulation factors.

Blood Coagulation Factors↗