Summary
In tropical freshwater reservoirs of Sri Lanka, which are linked in an aquatic network, bacterial abundance and production as well as virus abundance, frequency of viral infection and virus ...production were investigated together with a set of nutrient species (Kjeldahl‐N, NO3‐N, total P, soluble P, PO4‐P). At two characteristic seasons (wet season, dry season), samples were taken from two types of reservoirs (new upland impoundment and ancient, shallow lowland reservoir), each during 4 days at various depths of the entire water columns. Kjeldahl‐N and total P were greatly elevated in the wind‐mixed water body of the shallow impoundment during the dry season, whereas the deeper reservoir type exhibited no obvious seasonality. In SYBR green™‐stained samples, bacterial abundance showed no seasonal pattern in either reservoir type. Bacterial secondary production, however, was significantly elevated in the entire water column of the shallow impoundment under wind‐mixed conditions in the dry season. Highest abundance of virus particles and elevated frequency of bacteria containing mature phages were also observed in the shallow reservoir during the dry season indicating favourable conditions for virus propagation. Data from this aquatic network show that most virus parameters, such as abundance or frequency of visibly infected cells, were positively linked to bacterial abundance and production, but also to organic nitrogen or some phosphorus species. We calculated that between 13.2% and 46.1% of the bacterial standing stocks would be subjected to virus‐mediated mortality. Estimates of bacteriophage production revealed that from 10 × 109 up to 98 × 109 phages were produced per litre and day. Bacteria and viruses in the studied tropical freshwater system appear to be linked to various environmental conditions and may affect processes at the ecosystem scale.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The scientific community interested in atmospheric chemistry, gas emissions from vegetation fires, and carbon cycling is currently demanding information on the extent and timing of biomass burning at ...the global scale. In fact, the area and type of vegetation that is burned on a monthly or annual basis are two of the parameters that provide the greatest uncertainty in the calculation of gas and aerosol emissions and burned biomass. To address this need, an inventory of burned areas at monthly time periods for the year 2000 at a resolution of 1 km2 has been produced using satellite data and has been made freely available to the scientific community. In this paper, estimates of burned area and number of burn scars for four broad vegetation classes and reported at the country level for the year 2000 are presented using data taken from the inventory. Over 3.5 million km2 of burned areas were detected in the year 2000, of which approximately 80% occurred in areas described as woodlands and shrublands. Approximately 17% of the burned area occurred in grasslands and croplands, the remaining 3% occurred in forests. Almost 600,000 separate burn scars were detected. Descriptions of vegetation burning activity are given for ten regions. Finally, monthly burned area estimates are presented for the Central African Republic to illustrate the usefulness of these data for understanding, monitoring and managing vegetation burning activities.
This randomized, controlled trial assessed the efficacy of a home-based program to prevent functional decline among 188 frail, elderly persons. The program, which involved physical therapy and ...focused on improving underlying impairments in physical abilities, was more effective than an educational program in slowing the progression of disability with respect to activities of daily living.
A program with physical therapy was effective in slowing the progression of disability.
The ability to perform activities of daily living, such as bathing, dressing, and walking, is essential to living independently. Despite recent reductions in the prevalence of disability, the number of chronically disabled Americans 65 years of age or older currently exceeds 7 million.
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Because disability is associated with increased mortality
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and leads to increased rates of adverse outcomes, such as hospitalization, admission to a nursing home, and use of formal and informal home services,
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it places a substantial burden on elderly persons, informal caregivers, and health care resources.
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Therefore, interventions designed to prevent functional decline have the potential . . .
The analytical effect of the number of events per variable (EPV) in a proportional hazards regression analysis was evaluated using Monte Carlo simulation techniques for data from a randomized trial ...containing 673 patients and 252 deaths, in which seven predictor variables had an original significance level of
p < 0.10. The 252 deaths and 7 variables correspond to 36 events per variable analyzed in the full data set.
Five hundred simulated analyses were conducted for these seven variables at EPVs of 2, 5, 10, 15, 20, and 25. For each simulation, a random exponential survival time was generated for each of the 673 patients, and the simulated results were compared with their original counterparts. As EPV decreased, the regression coefficients became more biased relative to the true value; the 90% confidence limits about the simulated values did not have a coverage of 90% for the original value; large sample properties did not hold for variance estimates from the proportional hazards model, and the
Z statistics used to test the significance of the regression coefficients lost validity under the null hypothesis.
Although a single boundary level for avoiding problems is not easy to choose, the value of EPV = 10 seems most prudent. Below this value for EPV, the results of proportional hazards regression analyses should be interpreted with caution because the statistical model may not be valid.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Community-acquired bacterial meningitis causes substantial morbidity and mortality in adults.
To create and test a prognostic model for persons with community-acquired bacterial meningitis and to ...determine whether antibiotic timing influences clinical outcome.
Retrospective cohort study; patients were divided into derivation and validation samples.
Four hospitals in Connecticut.
269 persons who, between 1970 and 1995, had community-acquired bacterial meningitis microbiologically proven by a lumbar puncture done within 24 hours of presentation in the emergency department.
Baseline clinical and laboratory features and times of arrival in the emergency department, performance of lumbar puncture, and administration of antibiotics. The target end point was the development of an adverse clinical outcome (death or neurologic deficit at discharge).
For the total group, the hospital mortality rate was 27%. Fifty-six of 269 patients (21 %) developed a neurologic deficit, and in 9% the neurologic deficit persisted at discharge. Three baseline clinical features (hypotension, altered mental status, and seizures) were independently associated with adverse clinical outcome and were used to create a prognostic model from the derivation sample. The prediction accuracy of the model was determined by using the concordance index (c-index). For both the derivation sample (c-index, 0.73 95% CI, 0.65 to 0.81) and the validation sample (c-index, 0.81 CI, 0.71 to 0.92), the model predicted adverse clinical outcome significantly better than chance. For the total group, the model stratified patients into three prognostic stages: low risk for adverse clinical outcome (9%; stage I), intermediate risk (33%; stage II), and high risk (56%; stage III) (P=0.001). Adverse clinical outcome was more common for patients in whom the prognostic stage advanced from low risk (P=0.008) or intermediate risk (P=0.003) at arrival in the emergency department to high risk before administration of antibiotics.
In persons with community-acquired bacterial meningitis, three baseline clinical features of disease severity predicted adverse clinical outcome and stratified patients into three stages of prognostic severity. Delay in therapy after arrival in the emergency department was associated with adverse clinical outcome when the patient's condition advanced to the highest stage of prognostic severity before the initial antibiotic dose was given.
Over the last two decades, viruses in aquatic systems have been observed to modify, influence and control aquatic systems. Since the determination decades ago that viruses were abundant in aquatic ...ecosystems, researchers have demonstrated that viruses are pervasive and dynamic across the expanse and depth of all aquatic systems as well as at the water-sediment interface. There have been a wide range of methodological advancements during this time. To date, aquatic viruses have been suggested to play vital roles in global and small-scale biogeochemical cycling, community structure, algal bloom termination, gene transfer, and evolution of aquatic organisms. Even in harsh and difficult to study environments, aquatic and benthic viruses have been demonstrated to be major players in carbon cycling and recycling of nutrients from organic material. Taxonomic and metagenomic research has shown us that there are major globally-distributed groups, but that their genomes are filled with sequence information that has no similarity to sequences in existing bioinformatic databases. And while the field of viral ecology has expanded exponentially since the late 1980s, there is much that authors do not yet understand about virusmediated processes in aquatic systems. Important near-term steps include the combination of advanced metagenomic techniques with studies of function and population control, standardization of methodological approaches to facilitate global data acquisition without concern over methods-based artefacts, understanding of viral life strategies and their triggers, and the role of viruses in the transformation of organic matter. The purpose of this manuscript is to bring the reader a review of the recent advances in aquatic viral ecology in light of new areas of research, applications of viral ecology to real-world problems, and refinement of models of viral interactions on a range of scales.
BACKGROUND Screening for prostate cancer is done commonly in clinical practice, using prostate-specific antigen (PSA) tests or digital rectal examination (DRE). Evidence is lacking, however, to ...confirm a survival benefit among screened patients. We evaluated the effectiveness of PSA, with or without DRE, in reducing mortality. METHODS We conducted a multicenter nested case-control study at 10 Veterans Affairs medical centers in New England. Among 71 661 patients receiving ambulatory care between 1989 and 1990, 501 case patients were identified as men who were diagnosed as having adenocarcinoma of the prostate from 1991 through 1995 and who died sometime between 1991 and 1999. Control patients were men who were alive at the time the corresponding case patient had died, matched (1:1 ratio) for age and Veterans Affairs facility. The exposure variable (determined blind to case-control status) was whether PSA testing or DRE was performed for screening prior to the diagnosis of prostate cancer among case patients, with the same time interval for control patients. The association of screening and overall or cause-specific (prostate cancer) mortality was adjusted for race and comorbidity. RESULTS A benefit of screening was not found in our primary analysis assessing PSA screening and all-cause mortality (adjusted odds ratio, 1.08; 95% confidence interval, 0.71-1.64; P = .72), nor in a secondary analysis of PSA and/or DRE screening and cause-specific mortality (adjusted odds ratio, 1.13; 95% confidence interval, 0.63-2.06; P = .68). CONCLUSIONS These results do not suggest that screening with PSA or DRE is effective in reducing mortality. Recommendations for obtaining “verbal informed consent” from men regarding such screening should continue.Arch Intern Med. 2006;166:38-43-->
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A short overview of currently available studies on the ecology of viruses in running waters is provided. Additionally, a survey was conducted on the dynamics of both viruses and bacteria in an ...isolated floodplain segment of the Danube River and in the main channel near Vienna (Austria) during the hydrologically most dynamic phase (spring – summer). The study evaluates the differences between the main channel and the floodplain segment for suspended particle abundance and quality in relation to bacterial and viral parameters; both free-living forms and those attached to particles are examined. The hydrological disconnection of these two contrasting sampling sites influenced particle abundance and quality as well as the distribution of free-living vs. attached bacteria and viruses. The per-cell activity of bacteria attached to particles was significantly higher than that of the free-living fraction, particularly in the isolated water body. The abundance of bacteria and viruses on particles depended on particle quality (size). In the main channel, bacteria were significantly more abundant on surfaces (per mm
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) of suspended matter > 5 μm (aggregates with organic constituents) compared to particles < 5 μm (mostly mineral grains). In the isolated water body, both bacteria and viruses were more abundant on the larger particles/aggregates. Data from both locations revealed a positive correlation between abundance of particles > 5μm and attached viruses; free-living viruses were less abundant at high > 5μm particle loads. Only in the isolated floodplain section was viral abundance positively influenced by elevated per-cell productivity of potential host bacteria. The results demonstrate that system variability on a relatively small topographical scale (within a river-floodplain system) has consequences for microbial life, including viruses.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Both aspirin and warfarin when used alone are effective in the secondary prevention of vascular events and death after acute myocardial infarction. We tested the hypothesis that aspirin and warfarin ...therapy, when combined, would be more effective than aspirin monotherapy. Methods and Results- We conducted a randomized open-label study to compare the efficacy of warfarin (target international normalized ratio 1.5 to 2.5 IU) plus aspirin (81 mg daily) with the efficacy of aspirin monotherapy (162 mg daily) in reducing the total mortality in 5059 patients enrolled within 14 days of infarction and followed for a median of 2.7 years. Secondary end points included recurrent myocardial infarction, stroke, and major hemorrhage. Four hundred thirty-eight (17.3%) of 2537 patients assigned to the aspirin group and 444 (17.6%) of 2522 patients assigned to the combination group died (log-rank P=0.76). Recurrent myocardial infarction occurred in 333 patients (13.1%) taking aspirin and in 336 patients (13.3%) taking combination therapy (log-rank P=0.78). Stroke occurred in 89 patients (3.5%) taking aspirin and in 79 patients (3.1%) taking combination therapy (log-rank P=0.52). Major bleeding occurred more frequently in the combination therapy group than in the aspirin group (1.28 versus 0.72 events per 100 person years of follow-up, respectively; P<0.001). There were 14 individuals with intracranial bleeds in both the aspirin and combination therapy groups.
In post-myocardial infarction patients, warfarin therapy (at a mean international normalized ratio of 1.8) combined with low-dose aspirin did not provide a clinical benefit beyond that achievable with aspirin monotherapy.
To determine if passive immunization could decrease the incidence or severity of Klebsiella and Pseudomonas aeruginosa infections, patients admitted to intensive care units of 16 Department of ...Veterans Affairs and Department of Defense hospitals were randomized to receive either 100 mg/ kg intravenous hyperimmune globulin (lVIG), derived from donors immunized with a 24-valent Klebsiella capsular polysaccharide plus an 8-valent P. aeruginosa O-polysaccharide-toxin A conjugate vaccine, or an albumin placebo. The overall incidence and severity of vaccine-specific Klebsiella plus Pseudomonas infections were not significantly different between the groups receiving albumin and IVIG. There was some evidence that IVIG may decrease the incidence (2.7% albumin vs. 1.2% IVIG) and severity (1.0% vs. 0.3%) of vaccine-specific Klebsiella infections, but these reductions were not statistically significant. The trial was stopped because it was statistically unlikely that IVIG would be protective against Pseudomonas infections at the dosage being used. Patients receiving IVIG had more adverse reactions (14.4% vs. 9.2%).
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