Is photosynthetic enhancement sustained through three years of elevated CO2 exposure in 175-year-old Quercus robur?

Current carbon cycle models attribute rising atmospheric CO2 as the major driver of the increased terrestrial carbon sink, but with substantial uncertainties. The photosynthetic response of trees to elevated atmospheric CO2 is a necessary step, but not the only one, for sustaining the terrestrial carbon uptake, but can vary diurnally, seasonally and with duration of CO2 exposure. Hence, we sought to quantify the photosynthetic response of the canopy-dominant species, Quercus robur, in a mature deciduous forest to elevated CO2 (eCO2) (+150 µmol mol-1 CO2) over the first 3 years of a long-term free air CO2 enrichment facility at the Birmingham Institute of Forest Research in central England (BIFoR FACE). Over 3000 measurements of leaf gas exchange and related biochemical parameters were conducted in the upper canopy to assess the diurnal and seasonal responses of photosynthesis during the 2nd and 3rd year of eCO2 exposure. Measurements of photosynthetic capacity via biochemical parameters, derived from CO2 response curves, (Vcmax and Jmax) together with leaf nitrogen concentrations from the pre-treatment year to the 3rd year of eCO2 exposure, were examined. We hypothesized an initial enhancement in light-saturated net photosynthetic rates (Asat) with CO2 enrichment of ≈37% based on theory but also expected photosynthetic capacity would fall over the duration of the study. Over the 3-year period, Asat of upper-canopy leaves was 33 ± 8% higher (mean and standard error) in trees grown in eCO2 compared with ambient CO2 (aCO2), and photosynthetic enhancement decreased with decreasing light. There were no significant effects of CO2 treatment on Vcmax or Jmax, nor leaf nitrogen. Our results suggest that mature Q. robur may exhibit a sustained, positive response to eCO2 without photosynthetic downregulation, suggesting that, with adequate nutrients, there will be sustained enhancement in C assimilated by these mature trees. Further research will be required to understand the location and role of the additionally assimilated carbon.

Air Pollution and Climate Forcing of the Charcoal Industry in Africa.

The demand for charcoal in Africa is growing rapidly, driven by urbanization and lack of access to electricity. Charcoal production and use, including plastic burning to initiate combustion, release large quantities of trace gases and particles that impact air quality and climate. Here, we develop an inventory of current (2014) and future (2030) emissions from the charcoal supply chain in Africa that we implement in the GEOS-Chem model to quantify the contribution of charcoal to surface concentrations of PM2.5 and ozone and direct radiative forcing due to aerosols and ozone. We estimate that the charcoal industry in 2014 required 140-460 Tg of biomass and 260 tonnes of plastic and that industry emissions could double by 2030, so that methane emissions from the charcoal industry could outcompete those from open fires by 2025. In 2014, the largest enhancements in PM2.5 (0.5-1.4 µg m-3) and ozone (0.4-0.7 ppbv) occur around the densely populated cities in East and West Africa. Cooling due to aerosols (-100 to -300 mW m-2) is concentrated over dense cities, whereas warming due to ozone is widespread, peaking at 4.2 mW m-2 over the Atlantic Ocean. These effects will worsen with ongoing dependence on this energy source, spurred by rapid urbanization and absence of viable cleaner alternatives.

Dispersion of gas flaring emissions in the Niger delta: Impact of prevailing meteorological conditions and flare characteristics.

An understanding of the dispersion and level of emissions source of atmospheric pollutants; whether point, area or volume sources, is required to inform policies on air pollution and day-to-day predictions of pollution level. Very few studies have carried out simulations of the dispersion pattern and ground-level concentration of pollutants emitted from real-world gas flares. The limited availability of official data on gas flares from the oil and gas industries makes accurate dispersion calculations difficult. Using ADMS 5 and AERMOD, this study assessed the sensitivity of dispersion and ground-level concentration of pollutants from gas flares in the Niger Delta to prevailing meteorological condition; fuel composition; and flare size. Although, during the non-WAM (West African Monsoon) months (November and March), the simulated ground-level concentrations of pollutants from a single flare are lower, the dispersion of pollutants is towards both the inland and coastal communities. In the WAM months, the ground-level concentrations are higher and are dispersed predominantly over the inland communities. Less buoyant plumes from smaller flares (lower volume flow rates) and/or flaring of fuel with lower heat content results in higher ground-level concentrations in areas closer to the flare. Considering the huge number of flares scattered around the region, a mitigation of the acute local pollution level would be to combine short stacks flaring at lower volume flow rates to enhance the volume flow rate of a single exhaust, and hence, the buoyancy of the plume exiting the stack.

Gas flaring and resultant air pollution: A review focusing on black carbon.

Gas flaring is a prominent source of VOCs, CO, CO2, SO2, PAH, NOX and soot (black carbon), all of which are important pollutants which interact, directly and indirectly, in the Earth's climatic processes. Globally, over 130 billion cubic metres of gas are flared annually. We review the contribution of gas flaring to air pollution on local, regional and global scales, with special emphasis on black carbon (BC, "soot"). The temporal and spatial characteristics of gas flaring distinguishes it from mobile combustion sources (transport), while the open-flame nature of gas flaring distinguishes it from industrial point-sources; the high temperature, flame control, and spatial compactness distinguishes gas flaring from both biomass burning and domestic fuel-use. All of these distinguishing factors influence the quantity and characteristics of BC production from gas flaring, so that it is important to consider this source separately in emissions inventories and environmental field studies. Estimate of the yield of pollutants from gas flaring have, to date, paid little or no attention to the emission of BC with the assumption often being made that flaring produces a smokeless flame. In gas flares, soot yield is known to depend on a number of factors, and there is a need to develop emission estimates and modelling frameworks that take these factors into consideration. Hence, emission inventories, especially of the soot yield from gas flaring should give adequate consideration to the variation of fuel gas composition, and to combustion characteristics, which are strong determinants of the nature and quantity of pollutants emitted. The buoyant nature of gas flaring plume, often at temperatures in the range of 2000 K, coupled with the height of the stack enables some of the pollutants to escape further into the free troposphere aiding their long-range transport, which is often not well-captured by model studies.

Spatially-varying surface roughness and ground-level air quality in an operational dispersion model.

Urban form controls the overall aerodynamic roughness of a city, and hence plays a significant role in how air flow interacts with the urban landscape. This paper reports improved model performance resulting from the introduction of variable surface roughness in the operational air-quality model ADMS-Urban (v3.1). We then assess to what extent pollutant concentrations can be reduced solely through local reductions in roughness. The model results suggest that reducing surface roughness in a city centre can increase ground-level pollutant concentrations, both locally in the area of reduced roughness and downwind of that area. The unexpected simulation of increased ground-level pollutant concentrations implies that this type of modelling should be used with caution for urban planning and design studies looking at ventilation of pollution. We expect the results from this study to be relevant for all atmospheric dispersion models with urban-surface parameterisations based on roughness.

The atmospheric chemistry of trace gases and particulate matter emitted by different land uses in Borneo.

We report measurements of atmospheric composition over a tropical rainforest and over a nearby oil palm plantation in Sabah, Borneo. The primary vegetation in each of the two landscapes emits very different amounts and kinds of volatile organic compounds (VOCs), resulting in distinctive VOC fingerprints in the atmospheric boundary layer for both landscapes. VOCs over the Borneo rainforest are dominated by isoprene and its oxidation products, with a significant additional contribution from monoterpenes. Rather than consuming the main atmospheric oxidant, OH, these high concentrations of VOCs appear to maintain OH, as has been observed previously over Amazonia. The boundary-layer characteristics and mixing ratios of VOCs observed over the Borneo rainforest are different to those measured previously over Amazonia. Compared with the Bornean rainforest, air over the oil palm plantation contains much more isoprene, monoterpenes are relatively less important, and the flower scent, estragole, is prominent. Concentrations of nitrogen oxides are greater above the agro-industrial oil palm landscape than over the rainforest, and this leads to changes in some secondary pollutant mixing ratios (but not, currently, differences in ozone). Secondary organic aerosol over both landscapes shows a significant contribution from isoprene. Primary biological aerosol dominates the super-micrometre aerosol over the rainforest and is likely to be sensitive to land-use change, since the fungal source of the bioaerosol is closely linked to above-ground biodiversity.

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality.

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO(x) emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

Nitrogen management is essential to prevent tropical oil palm plantations from causing ground-level ozone pollution.

More than half the world's rainforest has been lost to agriculture since the Industrial Revolution. Among the most widespread tropical crops is oil palm (Elaeis guineensis): global production now exceeds 35 million tonnes per year. In Malaysia, for example, 13% of land area is now oil palm plantation, compared with 1% in 1974. There are enormous pressures to increase palm oil production for food, domestic products, and, especially, biofuels. Greater use of palm oil for biofuel production is predicated on the assumption that palm oil is an "environmentally friendly" fuel feedstock. Here we show, using measurements and models, that oil palm plantations in Malaysia directly emit more oxides of nitrogen and volatile organic compounds than rainforest. These compounds lead to the production of ground-level ozone (O(3)), an air pollutant that damages human health, plants, and materials, reduces crop productivity, and has effects on the Earth's climate. Our measurements show that, at present, O(3) concentrations do not differ significantly over rainforest and adjacent oil palm plantation landscapes. However, our model calculations predict that if concentrations of oxides of nitrogen in Borneo are allowed to reach those currently seen over rural North America and Europe, ground-level O(3) concentrations will reach 100 parts per billion (10(9)) volume (ppbv) and exceed levels known to be harmful to human health. Our study provides an early warning of the urgent need to develop policies that manage nitrogen emissions if the detrimental effects of palm oil production on air quality and climate are to be avoided.

Experimental arthritis: effect on growth parameters and total skeletal calcium.

Aim of the study was to investigate the possible mechanisms leading to stunted growth and osteoporosis in experimental arthritis. Fourty-two female rats of 7-8 weeks of age were randomly assigned to three groups of 14 animals each: (a) controls; (b) adjuvant-inoculated (AA); and (c) adjuvant-inoculated rats receiving 10 mg cyclosporin A (CsA) orally for 30 days. Biological parameters studied were: hindpaw swelling; vertebral length progression expressed as Delta increments between days 1 and 30 as a parameter of skeletal growth, and estimation of total skeletal mineral content by dual energy X-ray absorptiometry (n=10 each group) on day 30. Endocrine parameters measured were pulsatile release of growth hormone (rGH) on day 30 following jugular cannulation and measurement of insulin-like growth factor (IGF-1) in pooled plasma from rGH profiles. Results can be summarized as follows: Untreated AA rats exhibited local signs of inflammation in comparison with controls (hindpaw diameter 8.1-8.9 mm vs. 5.3-5.6 mm in controls). Treatment with CsA normalized this parameter (4.9-5.6 mm). Vertebral growth was significantly retarded in AA rats in comparison with controls (214+/-32 vs. 473+/-33 microm; p<0.001). Administration of CsA normalized vertebral size increment with a clear tendency to overgrowth (523+/-43 microm, n.s.). There was also a marked reduction in total skeletal mineral content in diseased (AA) rats as compared to controls (5.8+/-0.1 vs. 7.5+/-0.1g [OH-apatite]; p<0.001), and a moderate but significant increment above controls in the group receiving CsA (8.0+/-0.1 vs. 7.5+/-0.1g [OH-appatite]; p<0.04). Integrated rGH profiles exhibited a significant fall in arthritic rats and were completely restored to normal under CsA treatment. A trend toward higher rGH values was observed in the latter group (2908+/-554 in AA vs. 8317+/-1492 ng/ml/240 min in controls; p<0.001, and 10940+/-222 ng/ml/240 min, n.s. in the CsA group). There was a good correlation between skeletal growth and rGH pulsatility (r=0.81; p<0.001). IGF-1 followed a similar pattern (630+/-44 in AA vs. 752+/-30 ng/ml in controls; p<0.04, and 769+/-59 ng/ml in the CsA group, n.s. vs. controls). Thus, a clear tendency to skeletal overgrowth following treatment was observed in agreement with the hormonal data. It can therefore be concluded that, in experimental arthritis, attenuated GH-spiking and reduced circulating IGF-1 appear to be causally related to growth retardation, probably mimicking signs and symptoms observed in juvenile arthritis. Therapy with CsA is followed by normalization of hormonal and biological parameters accompanied by a catch up phenomenon in skeletal growth which is also observed clinically in juvenile arthritis. Generalized osteopenia is a prominent feature seemingly connected with the growth abnormalities as they parallel each other during the evolution of the disease and respond equally to therapy.

The changing face of infection: a comparative review of admissions to a regional infection unit over three decades.

BACKGROUND AND AIMS: Our group previously published retrospective analyses of 12 months of admissions to the Grampian Regional Infectious Diseases Unit from 1980-81 and from 1991. This study aimed to collect data in 2001 and to compare annual admission numbers, diagnoses, duration of stay and outcome in 1980-81, 1991 and 2001. METHODS: Data on all admissions was collected prospectively throughout 2001. This was compared with the previously published data. RESULTS: Total admissions rose from 605 in 1980-81 to 900 in 1991 and to 1152 in 2001. Sixty one percent of admissions in 1980-81 were confirmed as having infection compared to 72% in 1991 and to 83% in 2001. The most common reason for admission in 2001 was skin and soft tissue infection, but this was only the ninth commonest reason in 1981. Mean length of stay fell from 9.6 days in 1980-81 to 7.4 days in 1991 and to 5.5 days in 2001. The mortality rate fell from 3.1% in 1981 and 1991 to 1.0% in 2001. CONCLUSIONS: This study demonstrates significant changes in type, number and outcome of admissions to a regional infection unit. We discuss possible reasons for these changes.

Point prevalence survey of antibiotic use in Scottish hospitals utilising the Glasgow Antimicrobial Audit Tool (GAAT).

A point prevalence survey of antimicrobial prescribing was performed in 10 Scottish hospitals using the Glasgow Antimicrobial Audit Tool (GAAT). Appropriateness of the intravenous (IV) route was determined by an infectious diseases physician (IDP) and by a computerised algorithm. The IDP also estimated IV agent appropriateness. Each hospital was surveyed on a single day. Of 3826 patients surveyed, 1079 (28.3%) received an antibiotic, 381 (35.3%) intravenously; 197 (28.2%) orally treated had prior IV therapy. Median duration of IV was 4 days (IQR 2-7 days) and oral switch was 3.5 days (2-6). IV route was appropriate in 84% (IDP) and 84.8% (algorithm). Choice of agent was appropriate in 80% (IDP). Third-generation cephalosporins (3GC) (28.3%) were most frequent, followed by co-amoxiclav (20.2%), metronidazole (19.2%) and glycopeptides (18.6%). Regional differences were seen. The study shows it is possible to coordinate, collect and compare data from UK hospitals using the GAAT. Data may usefully inform local and national audit and support prescribing initiatives.

A seroepidemiological study of bovine pestivirus in Queensland beef and dairy herds conducted in 1994/95.

OBJECTIVE: To describe the distribution and prevalence of cattle herds with detectable antibody to bovine pestivirus in Queensland in 1994/95. MATERIALS AND METHODS: The study used 7,838 serum samples collected from 250 herds in Queensland, as part of a structured animal health surveillance program conducted in 1994 and 1995. Samples were collected from female cattle bred on the property. In each herd, 10 to 20 heifers less than two years of age and 10 to 15 older cows were sampled giving a 95% probability of detecting one or more seropositive animals if the seroprevalence was approximately 10% or greater. Sera were analysed for antibodies to bovine pestivirus using a virus neutralisation test. RESULTS: Total cattle numbers in sampled herds varied from 62 to 24,600 head, while total area of properties sampled varied from 50 to 395,400 hectares. Eleven percent of herds contained no seropositive animals among those sampled, and in 38% of herds, all sampled cattle aged one to two years of age were seronegative. There was a trend for larger herds to have one or more animals seropositive for bovine pestivirus (chi-squared for Linear trend = 3.656, p = 0.056). Herds with more than 500 head of cattle were significantly more likely than herds with less than 500 head to contain one or more seropositive animals in any age group (prevalence ratio = 1.12; 95% confidence interval 1.01 - 1.23; p = 0.026). Age specific seroprevalence increased from around 10% in heifers, to between 75% and 85% in cows aged 10 years. The average annual incidence risk for bovine pestivirus infection varied from 0.12 to 0.24 seroconversions per cattle year at risk, and did not vary with age. The overall crude seroprevalence adjusted for herd size was 45%. There was a wide range of seroprevalence recorded for each level of stocking intensity. CONCLUSIONS: This survey provides valuable baseline data on bovine pestivirus infection in Queensland cattle herds.

Audit of an antibiotic policy and microbiological investigations for treating bacteraemia in a large teaching hospital.

An audit of different approaches to guide empirical therapy in 78 cases of bacteraemia revealed poor utilisation of the antibiotic policy with resulting inadequate (P=0.005) or excessive (P<0.00001) antibiotic treatment and a trend to increased mortality. Eighty-seven percent of blood cultures were positive on Gram-stain within 24 h but streamlined therapy was still judged excessive in 27%. The results show poor utilisation of an up-to-date antibiotic policy but confirm its potential benefits and the ability of traditional culture methods to guide antibiotic therapy in a useful time-scale.

Increasing incidence of acute hepatitis B virus infection referrals to the Aberdeen Infection Unit: a matter for concern.

OBJECTIVES: To assess the epidemiology and clinical outcomes of acute hepatitis B virus (HBV) infections presenting to a regional Infection Unit over a ten year period--with reference to the issues of injection drug use and strategies aimed at reducing transmission, notably needle exchange and immunisation programmes. METHODS: A retrospective casenote review of all patients with acute HBV managed at the Infection Unit in Aberdeen between 1991-2000. RESULTS: One hundred and nineteen (119) patients with acute HBV infection were managed during the period of review. The annual number of patients increased from a mean of 3.3/year during the years 1991-96 to 46 in 2000. The risk factors associated with HBV infection were being an injection drug user (IDU) in 57 (47.9%), heterosexual sex in 22 (18.5%), sex with an IDU in 4 (3.4%), men who had sex with men in 10 (8.4%), tattooing in 1 (0.8%), a needle stick injury in 1 (0.8%), trauma 1 (0.8%) and unknown in 23 (19.3%). Many of these patients had "dabbled" in drug use. Thirty-one (54.4%) of the IDU patients had previously been hospitalised with drug-related medical problems. Eighteen (31.6%) of the IDUs were receiving methadone at the time of presentation. CONCLUSIONS: There is an epidemic of HBV infection in the Grampian region of Scotland currently. Forty-six (65.7%) of the 70 infected patients diagnosed during 2000 were seen at the Infection Unit. The remainder had mild or asymptomatic disease and were managed in the community. This epidemic has occurred despite extensive use of local needle exchange facilities and might reflect missed opportunities to immunise IDUs against HBV infection. A co-ordinated approach is now in place to immunise IDUs and other high-risk groups, but the use of universal immunisation demands consideration.

Three years experience of adults admitted to hospital in north-east Scotland with E. coli O157.

UNLABELLED: To describe the epidemiology, clinical features, treatment and outcomes of adults with E. coli O157 infection presenting to Aberdeen Royal Infirmary over a three year period. METHODS: A retrospective casenote review. RESULTS: Thirty-two confirmed cases of E. coli O157 infection were admitted between 1997 and 2000. The median age was 58 years (range 16-93). Ten patients (31%) were from the city of Aberdeen and 22 (69%) from surrounding rural areas. Twenty-seven patients (85%) presented between May and October. The source of infection was unknown or unconfirmed in all cases. Bloody diarrhoea was present in 30 (94%). Leucocytosis was present in 18 (63%) but only four patients (13%) had a fever. Six of the 32 patients (19%) developed Haemolytic-Uraemic Syndrome (HUS) of whom 2 died. Ten patients received antibiotics of whom two developed HUS. Twenty-seven of the 32 (85%) had made a full recovery by time of discharge, three (9%) had impaired renal function and two (6%) died in hospital. CONCLUSION: E. coli O157 infection tends to occur sporadically in rural areas in North East Scotland. It is not usually associated with fever. Infection occurs more commonly in the summer and autumn. HUS complicates infection in almost one fifth of patients.

Presenting clinical features and C-reactive protein in the prediction of a positive stool culture in patients with diarrhoea.

OBJECTIVES: To devise a scoring system by which clinical features and C-reactive protein (CRP) can be used to predict a positive stool culture in patients admitted with acute diarrhoea. METHODS: One hundred and thirty-two patients admitted to the Regional Infection Unit with diarrhoea thought to be due to bacterial gastroenteritis were included. Clinical features, CRP and outcome of stool culture were recorded, together with the final diagnosis. RESULTS: Forty-one patients had bacterial gastroenteritis characterized by the isolation of a bacterial enteropath (BGE). Sixty-three patients had non-specific gastroenteritis, defined as more than three loose stools per day with no bacterial enteropath isolated (NSGE). In 28 patients another diagnosis was made (Others). More of the patients with BGE (91%) had abdominal pain as compared with those with NSGE (67%) and Others (61%) (P=0.01). The mean duration of symptoms was longer in the Others group (6.14 days) as compared with patients with BGE (3.29) and NSGE (3.25) (P=0.01). The mean CRP was significantly higher in those with BGE (113.9mg/l) and Others (116.9mg/l) as compared to the NSGE patients (38.9mg/l) (P=0.001). A scoring system was devised which incorporated the presence or absence of abdominal pain (+10 or 0), the duration of symptoms (-10, for 5 or more days, 0 for less than 5 days of symptoms) and the CRP (CRP<50=0, CRP>50=5). A score of 15 or more predicted 79% of patients with BGE, while a score of <15 predicted 87% of those with NSGE and 86% of those with another diagnosis. CONCLUSIONS: This simple scoring system may be useful in predicting the positivity of stool culture, and therefore may be helpful in targeting those small number of patients who require antimicrobial therapy after hospital admission. We would not, however, favour reliance on this scoring system alone to choose whom to treat with antimicrobials.

Impact of the oil industry on malaria diagnosis and management in north-east Scotland (1992-99).

In order to assess the current pattern of malaria presenting to the Aberdeen Infection Unit a retrospective casenote review was undertaken of 110 patients admitted with that diagnosis between 1st January 1992 and 31st August 1999. Oil-related work was the reason for travel in 48 (43.6%) of the UK residents, holiday in 35 (31.8%), backpacking in 8 (7.3%) and other work in 5 (4.5%). Sixty-five patients (59.1%) had PL falciparum malaria (pure or mixed), 25 (22.7%) had PL vivax, 6 (5.4%) PL ovale and 3 (2.7%) PL malariae infection. No prophylaxis had been taken by 66% of the 47 UK-based oil workers and by 36% of the other 48 UK residents who had returned from Africa. There is a need for better education of oil workers and holidaymakers travelling to areas endemic for malaria. We are now setting up a travel advisory service in our Unit to address the problem.

High prevalence of iliofemoral venous thrombosis with severe groin infection among injecting drug users in North East Scotland: successful use of low molecular weight heparin with antibiotics.

Injecting drug use, mainly of heroin, currently represents a major public health issue in the North East of Scotland. The recent tendency of the committed injecting drug user to inject into the groin has created novel problems for the Infection Unit. Data are presented on 20 consecutive patients admitted between 1994 and 1999 with iliofemoral venous thromboses, often complicated by severe soft tissue infections and bacteraemia as a result of heroin injection into the femoral vein. Nine had coexistent groin abscesses, four had severe streptococcal soft tissue infection of the right thigh, groin and lower abdomen, and two had coincidental soft tissue infections of the upper limb. Nine were bacteraemic on admission. All of the patients were chronic injecting drug users with a median injection duration of 6.5 years. The 18 patients tested for hepatitis C virus were all seropositive. None of the 14 patients tested was positive for HIV. Seventeen patients were treated with subcutaneous low molecular weight heparin (tinzaparin), three having received intravenous unfractionated heparin initially. The tinzaparin was self administered and given for a median duration of seven weeks. One patient declined to have any treatment. Three months after presentation eight patients were asymptomatic, seven had a persistently swollen leg, and five were lost to follow up. None developed clinically apparent pulmonary embolism after institution of anticoagulant therapy. The management of iliofemoral venous thrombosis in injection drug users is problematic because of poor venous access, non-compliance with prescribed treatment, ongoing injecting behaviour, and coexistent sepsis. It is unlikely that a randomised trial of standard treatment with heparin and warfarin versus low molecular weight heparin alone would be practical in this patient group. These retrospective data indicate that the use of tinzaparin in injecting drug users is feasible and appears to result in satisfactory clinical responses. The possibility of concomitant infection in injecting drug users with venous thrombosis should always be addressed, as it appears to be a common phenomenon. Early drainage of abscesses and antimicrobial chemotherapy, often administered intramuscularly or orally because of lack of peripheral venous access, is central to the appropriate care of these patients.

Assessment of the efficacy, safety and quality of gentamicin use in Aberdeen Royal Infirmary.

Fifty-five patients who received od gentamicin were studied. The protocol for od gentamicin was followed in 23/55 (48%). Cure rates were 22/23 (96%) when the protocol was followed and 24/32 (75%) when not followed (P = 0.06). Toxicity was more common in those in whom the protocol was not followed (9/32; 28%) than in those in whom it was followed (1/23; 4%) (P< 0.05). The number needed to treat with the protocol to produce one additional cure was 4.84 (95% CI 2.64 to 28.66) and the number needed to treat to prevent one case of toxicity was 3.61 (95% CI 2.16 to 10.99).

Duration of intravenous therapy and hospital stay according to choice of empirical antimicrobial treatment for community-acquired respiratory infection.

A review of patients admitted to medical wards with respiratory infection was undertaken to look for differences in duration of intravenous (IV) therapy and length of patient stay based on the class of IV antimicrobial used in treatment. Data was analysed from 231 patients with community-acquired respiratory infection who were treated empirically for at least 24 h with either an IV cephalosporin (146 patients) or an IV penicillin or macrolide (85 patients). The severity of illness and indication for IV treatment was similar in each group. Those treated with a cephalosporin received IV therapy for a significantly longer period (mean = 4.44 days, SD = 2.6) than those given a penicillin or macrolide (mean = 3.3 days, SD = 1.8): P < 0.001. Patient stay was significantly longer in the cephalosporin group (mean = 11.6 days, SD = 10.4) than the penicillin/macrolide group (mean = 9.4 days, SD = 6.3): P = 0.04. These differences are most readily accounted for by the absence from the hospital formulary of a third generation oral cephalosporin, a drug that might be regarded as an obvious form of follow-on therapy in patients treated empirically with an injectable cephalosporin.