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Biomedical subjects

J Gillon

Publications and source records attributed to J Gillon.

At least 19 recordsLinked to original sources
PubMed2001

Influence of carbonic anhydrase activity in terrestrial vegetation on the 18O content of atmospheric CO2.

The oxygen-18 (18O) content of atmospheric carbon dioxide (CO2) is an important indicator of CO2 uptake on land. It has generally been assumed that during photosynthesis, oxygen in CO2 reaches isotopic equilibrium with oxygen in 18O-enriched water in leaves. We show, however, large differences in the activity of carbonic anhydrase (which catalyzes CO2 hydration and 18O exchange in leaves) among major plant groups that cause variations in the extent of 18O equilibrium (theta(eq)). A clear distinction in theta(eq) between C3 trees and shrubs, and C4 grasses makes atmospheric C18OO a potentially sensitive indicator to changes in C3 and C4 productivity. We estimate a global mean theta(eq) value of approximately 0.8, which reasonably reconciles inconsistencies between 18O budgets of atmospheric O2 (Dole effect) and CO2.

Atmosphere↗
PubMed2001

Detection of enterovirus viraemia in blood donors.

BACKGROUND AND OBJECTIVES: The infrastructure established for screening blood donations for hepatitis C virus has enabled large-scale population testing for other viruses which are potentially transmissible by transfusion of blood components and plasma-derived blood products. We have measured the frequency of viraemia of enteroviruses and parechoviruses in 83 600 Scottish blood donors to allow an initial assessment of their risk to blood safety. MATERIALS AND METHODS: Plasma samples collected from blood donors over 7 calendar months were tested anonymously in mini-pools of 95 donations, by polymerase chain reaction (PCR) for human enterovirus and parechovirus sequences. RESULTS: A total of 19 mini-pools, from the 880 that were tested, were PCR-positive for enterovirus RNA, predicting a donor prevalence of 0.023%. Enterovirus sequences were not detected in factor VIII or IX clotting factor concentrates. None of the 230 mini-pools or concentrates contained detectable parechovirus RNA. CONCLUSIONS: The prevalence of enterovirus viraemia detected in this study predicts that at least 1000 enterovirus-contaminated blood components are transfused per year in the UK. The frequency of transmission and clinical outcome after exposure to enterovirus-contaminated blood components in recipients is unknown.

Base Sequence↗
PubMed2000

Carbon fixation.

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Carbon↗
PubMed2000

Natural history of haemoglobin levels in female blood donors with haemoglobin levels of 120-124 g/l at presentation.

BACKGROUND AND OBJECTIVES: In order to assess the effects of proposed changes to UK guidelines, female blood donors with venous haemoglobin (Hb) levels of 120-124 g/l were followed up over a period of 18 months in order to assess frequency of attendance and ability to donate in relation to changes in Hb and red cell indices, and to determine the effects of inter-donation interval and iron supplementation on outcomes. MATERIALS AND METHODS: Venous samples were analysed using the Haemocue haemoglobinometer at each attendance, and a donation was taken if the Hb was 120 g/l or greater. Full blood counts were done on each sample using the Coulter Model T890. A postal questionnaire was used to elicit additional information, including use of iron supplements. RESULTS: The 392 donors enrolled in the study gave 655 subsequent attendances, resulting in 468 donations (1.5 donations/donor/year). Donors who subsequently had Hb <120 g/l had a tendency to lower initial mean corpuscular volume (MCV), but MCV could not be used as an indicator of future performance. 23% of donors reported use of iron supplements, but those donating 3 times or more were no more likely to use iron supplementation (20%). No statistical relationship was found between inter-donation interval and ability to donate at subsequent attendances. CONCLUSIONS: Female donors with borderline Hb levels proved to be highly committed, with a donation rate of 1. 5/donor/year during the period of follow-up. MCV is not a useful predictor of ability to donate in the future. This subset of the donor population shows wide variation in Hb level over time, and this is largely independent of iron supplementation or inter-donation interval.

Anemia, Iron-Deficiency↗
PubMed1998

Detection of a novel DNA virus (TTV) in blood donors and blood products.

BACKGROUND: A newly discovered DNA virus, transfusion-transmitted virus (TTV), has been implicated as a cause of post-transfusion hepatitis. We investigated the frequency of TTV viraemia in UK blood donors, and the extent to which TTV contaminates blood products such as factor VIII and IX clotting factors. We also investigated the possible aetiological role of TTV in cryptogenic fulminant hepatic failure (FHF). METHODS: We extracted DNA from plasma of blood donors and patients with FHF, and from blood products (factor VIII and IX clotting-factor concentrates, immunoglobulin preparations). We detected TTV by PCR using primers from a conserved region in the TTV genome. FINDINGS: TTV viraemia was detected in 19 (1.9%) of 1000 non-remunerated regular blood donors. Infection occurred more frequently in older donors (mean age 53 years), compared with the age prolife of donors infected with hepatitis C virus and other parenterally-transmitted viruses. TTV contamination was found in ten (56%) of 18 batches of factor VIII and IX concentrate manufactured from such non-remunerated donors, and in seven (44%) of 16 batches of commercially available products. Whereas solvent or detergent treatment had little effect on the detection of TTV in factor VIII and IX by PCR, this virucidal step seemed to inactivate TTV infectivity. TTV infection was detected in four (19%) of 21 patients with FHF; in three cases, infection was detected at the onset of disease and could thus not be excluded from its aetiology. INTERPRETATION: TTV viraemia is frequent in the blood-donor population, and transmission of TTV through transfusion of blood components may have occurred extensively. Clinical assessment of infected donors and recipients of blood and blood products, and assessment of TTV's aetiological role in hepatic and extra-hepatic disease, are urgently needed.

Adult↗
PubMed1998

Prevalence, incidence, and clinical characteristics of hepatitis G virus/GB virus C infection in Scottish blood donors.

The prevalence, incidence, clinical features, and natural history of hepatitis G virus (HGV) or GB virus C (GBV-C) were investigated in a non-remunerated blood donor population to determine its clinical significance and its impact on blood safety. Of 1020 regular blood donors, 23 (2.25%) were positive for plasma HGV/GBV-C RNA. Alanine aminotransferase levels were lower than in uninfected donors (median, 20 IU/mL; 32 IU/mL in controls; P=.015). Clinical examination produced no other evidence for hepatitis or for shared nonhepatic diseases. Fifteen of 17 donors excreted HGV/GBV-C in saliva (mean level, 8x103 copies of RNA/mL). Testing of previous donations indicated an incidence of 170-200 new infections with HGV/GBV-C per 100,000 donor-years. The absence of further clinicopathologic data and the limitations of current polymerase chain reaction-based methods for screening suggests that it is neither necessary nor practical to commence screening.

Adult↗
PubMed1996

Study on medical donor deferrals at sessions.

A 10-month audit of reasons for donor medical deferral at sessions was carried out in two Scottish regions of the SNBTS. Six thousand deferred donors were assessed. Although the deferred donor population mirrored the attending donor population in both regions, significantly more donors, both new and regular, were deferred in the Edinburgh and South East region, compared with the North East. The main differences in deferral were attributable to three clinical conditions (cervical carcinoma in situ, other gynaecological conditions and hypertension) and to donors admitting to high-risk behaviour. Although the staff in the deferral process - doctors, nurses and clerks - were involved in roughly equal proportions in both regions, the spectrum of medical conditions seen by each staff grouping appeared to be different in each region. The staff in the South East appeared to have made more correct decisions. Further analysis and audits are being undertaken in areas highlighted by this study.

Blood Donors↗