10 research outputs found
Why does Anopheles Arabiensis predominate over An. Gambiae Sensu Stricto in hot and arid conditions?
No full textThe mosquitoes Anopheles arabiensis má An. gambiae s. s. are two sibling species that are the most efficient vectors of malaria across Africa. Although they occursympatrically over much of the continent, An. arabiensis predominates in hotter and drier conditions whilst An. gambiae s. s. is more abundant in wetter conditions. This study explored the physiological and behavioural factors responsible for the different spatial and temporal distributions of these species. In the laboratory adult An.arabiensis exhibit a three-fold longer survival than Art. gambiae s.s. at high temperatures and low humidity. Moreover An. arabiensis is tolerant of high temperatures that are actively avoided by An. gambiae S.S. This behavioural response to high temperatures was also observed in adult populations of both species in the field տ The Gambia. The interspecific difference observed in survival rates is not apparent in the 24 hour activity levels. Neither species could sustain periods of activity at temperatures above 30 c. An. arabiensis loses water at a proportionately lower rate at 40 c and 30%RH, and contained a disproportionately greater reserve of accessible water, namely haemolymph, than An. gambiae ร.ร. Although heat-shocked groups of both species expressed higher levels of heat shock proteins when compared to control groups, this did not relate to improved knock-down resistance. There were less obvious differences between the species in the larval stage. In the laboratory An. arabiensis larvae exhibited a greater survival to adulthood at 35 c than An, gambiae ร.ร., when reared separately and together. However, in the field An. arabieหsis did not dominate the hottest breeding sites in The Gambia in the dry season. Larvae of both species dived away from 40 c water surface temperatures, though for short periods only. It is argued that a better tolerance of hot and drying resting conditions in An. Arabiensis may result in longer-term improvements in survival rates compared to An. Gambiae S.S
Regeneration in gap models: priority issues for studying forest responses to climate change
No full textRecruitment algorithms in forest gap models are examined with particular regard to their suitability for simulating forest ecosystem responses to a changing climate. The traditional formulation of recruitment is found limiting in three areas. First, the aggregation of different regeneration stages (seed production, dispersal, storage, germination and seedling establishment) is likely to result in less accurate predictions of responses as compared to treating each stage separately. Second, the relatedassumptions that seeds of all species are uniformly available and that environmental conditions are homogeneous, are likely to cause overestimates of future species diversity and forest migration rates. Third, interactions between herbivores (ungulates and insect pests) and forest vegetation are a big unknown with potentially serious impacts in many regions. Possible strategies for developing better gap model representations for the climate-sensitive aspects of each of these key areas are discussed. A working example of a relatively new model that addresses some of these limitations is also presented for each case. We conclude that better models of regeneration processes are desirable for predicting effects of climate change, but that it is presently impossible to determine what improvements can be expected without carrying out rigorous tests for each new formulation
Modelling surface climate over complex terrain for landscape ecology
No full textClimate exerts a fundamental control on ecosystem function, species diversity and distribution. Topographic variability may influence surface climate, through processes operating at a landscape- scale. To quantify and model such influences, the topography of a 72 km(^2) area of complex terrain, (including the Moor House National Nature Reserve in northern England) was analysed at 50 m resolution. A suite of topographic variables was created, including distance relative to the Pennine ridge (dist), and elevation difference between each grid cell and the lowest grid cell within a specified neighbourhood {drain). Automatic weather stations (AWS) were deployed in a series of networks to test hypothetical relationships between landscape and climate. Daily maximum air temperature, daily mean soil temperature and daily potential evapotranspiration can be modelled spatially using a daily lapse rate calculated from the difference between daily observations made at two base stations. On days with a south easterly wind direction, daily mean temperature is estimated as a function of lapse rate and dist; the spatial behaviour of temperature is consistent with a föhn mechanism. Daily minimum temperature is modelled using lapse rate and drain on days with a lapse rate of minimum temperature shallower than -2.03 x 10 C m(^-1), incorporating the effects of katabatic air flow. Daily solar radiation surfaces are estimated by a GIS routine that models interactions between slope and solar geometry and accounts for daily variations in cloudiness and daylight duration. The daily climate surfaces were tested using data measured at a range of AWS locations during different times of year. The accuracy of the daily surfaces is not seasonally-dependent. The spatial climate data are particularly well suited to landscape-scale ecology because the methods account for prevailing topoclimatic constraints and because separate climate surfaces are generated for each day, capturing the high frequency variability characteristic of upland regions
Regular wine consumption in chronic heart failure. impact on outcomes, quality of life, and circulating biomarkers
No full textBackground-Moderate, regular alcohol consumption is generally associated with a lower risk of cardiovascular events but data in patients with chronic heart failure are scarce. We evaluated the relations between wine consumption, health status, circulating biomarkers, and clinical outcomes in a large Italian population of patients with chronic heart failure enrolled in a multicenter clinical trial. Methods and Results-A brief questionnaire on dietary habits was administered at baseline to 6973 patients enrolled in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca-Heart Failure (GISSI-HF) trial. The relations between wine consumption, fatal and nonfatal clinical end points, quality of life, symptoms of depression, and circulating biomarkers of cardiac function and inflammation (in subsets of patients) were evaluated with simple and multivariable-adjusted statistical models. Almost 56% of the patients reported drinking at least 1 glass of wine per day. After adjustment, clinical outcomes were not significantly different in the predefined 4 groups of wine consumption. However, patients with more frequent wine consumption had a significantly better perception of health status (Kansas City Cardiomyopathy Questionnaire score, adjusted P<0.0001), less frequent symptoms of depression (Geriatric Depression Scale, adjusted P=0.01), and lower plasma levels of biomarkers of vascular inflammation (osteoprotegerin and C-terminal proendothelin-1, adjusted P<0.0001, and pentraxin-3, P=0.01) after adjusting for possible confounders. Conclusions-We show for the first time in a large cohort of patients with chronic heart failure that moderate wine consumption is associated with a better perceived and objective health status, lower prevalence of depression, and less vascular inflammation, but does not translate into more favorable clinical 4-year outcomes. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT0033633
Prognostic impact of diabetes and prediabetes on survival outcomes in patients with chronic heart failure: a post-hoc analysis of the GISSI-HF (Gruppo Italiano per lo Studio della Sopravvivenza nella Insufficienza Cardiaca-Heart Failure) trial
No full textBackground-The independent prognostic impact of diabetes mellitus (DM) and prediabetes mellitus (pre-DM) on survival outcomes in patients with chronic heart failure has been investigated in observational registries and randomized, clinical trials, but the results have been often inconclusive or conflicting. We examined the independent prognostic impact of DM and pre-DM on survival outcomes in the GISSI-HF (Gruppo Italiano per lo Studio della Sopravvivenza nella Insufficienza Cardiaca-Heart Failure) trial.Methods and Results-We assessed the risk of all-cause death and the composite of all-cause death or cardiovascular hospitalization over a median follow-up period of 3.9 years among the 6935 chronic heart failure participants of the GISSI-HF trial, who were stratified by presence of DM (n= 2852), pre-DM (n= 2013), and non-DM (n= 2070) at baseline. Compared with non-DM patients, those with DM had remarkably higher incidence rates of all-cause death (34.5% versus 24.6%) and the composite end point (63.6% versus 54.7%). Conversely, both event rates were similar between non-DM patients and those with pre-DM. Cox regression analysis showed that DM, but not pre-DM, was associated with an increased risk of all-cause death (adjusted hazard ratio, 1.43; 95% CI, 1.28-1.60) and of the composite end point (adjusted hazard ratio, 1.23; 95% CI, 1.13-1.32), independently of established risk factors. In the DM subgroup, higher hemoglobin A1c was also independently associated with increased risk of both study outcomes (all-cause death: adjusted hazard ratio, 1.21; 95% CI, 1.02-1.43; and composite end point: adjusted hazard ratio, 1.14; 95% CI, 1.01-1.29, respectively).Conclusions-Presence of DM was independently associated with poor long-term survival outcomes in patients with chronic heart failure
Regular Wine Consumption in Chronic Heart Failure: Impact on Outcomes, Quality of Life, and Circulating Biomarkers
No full textBackground-Moderate, regular alcohol consumption is generally associated with a lower risk of cardiovascular events but data in patients with chronic heart failure are scarce. We evaluated the relations between wine consumption, health status, circulating biomarkers, and clinical outcomes in a large Italian population of patients with chronic heart failure enrolled in a multicenter clinical trial. Methods and Results-A brief questionnaire on dietary habits was administered at baseline to 6973 patients enrolled in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca-Heart Failure (GISSI-HF) trial. The relations between wine consumption, fatal and nonfatal clinical end points, quality of life, symptoms of depression, and circulating biomarkers of cardiac function and inflammation (in subsets of patients) were evaluated with simple and multivariable-adjusted statistical models. Almost 56% of the patients reported drinking at least 1 glass of wine per day. After adjustment, clinical outcomes were not significantly different in the predefined 4 groups of wine consumption. However, patients with more frequent wine consumption had a significantly better perception of health status (Kansas City Cardiomyopathy Questionnaire score, adjusted P<0.0001), less frequent symptoms of depression (Geriatric Depression Scale, adjusted P=0.01), and lower plasma levels of biomarkers of vascular inflammation (osteoprotegerin and C-terminal proendothelin-1, adjusted P<0.0001, and pentraxin-3, P=0.01) after adjusting for possible confounders. Conclusions-We show for the first time in a large cohort of patients with chronic heart failure that moderate wine consumption is associated with a better perceived and objective health status, lower prevalence of depression, and less vascular inflammation, but does not translate into more favorable clinical 4-year outcomes. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT0033633
Prognostic impact of diabetes and prediabetes on survival outcomes in patients with chronic heart failure: A post-hoc analysis of the GISSI-HF (Gruppo Italiano per lo Studio della Sopravvivenza nella Insufficienza Cardiaca-Heart Failure) trial
No full textBackground-The independent prognostic impact of diabetes mellitus (DM) and prediabetes mellitus (pre-DM) on survival outcomes in patients with chronic heart failure has been investigated in observational registries and randomized, clinical trials, but the results have been often inconclusive or conflicting. We examined the independent prognostic impact of DM and pre-DM on survival outcomes in the GISSI-HF (Gruppo Italiano per lo Studio della Sopravvivenza nella Insufficienza Cardiaca-Heart Failure) trial. Methods and Results-We assessed the risk of all-cause death and the composite of all-cause death or cardiovascular hospitalization over a median follow-up period of 3.9 years among the 6935 chronic heart failure participants of the GISSI-HF trial, who were stratified by presence of DM (n=2852), pre-DM (n=2013), and non-DM (n=2070) at baseline. Compared with non-DM patients, those with DM had remarkably higher incidence rates of all-cause death (34.5% versus 24.6%) and the composite end point (63.6% versus 54.7%). Conversely, both event rates were similar between non-DM patients and those with pre-DM. Cox regression analysis showed that DM, but not pre-DM, was associated with an increased risk of all-cause death (adjusted hazard ratio, 1.43; 95% CI, 1.28-1.60) and of the composite end point (adjusted hazard ratio, 1.23; 95% CI, 1.13-1.32), independently of established risk factors. In the DM subgroup, higher hemoglobin A1c was also independently associated with increased risk of both study outcomes (all-cause death: adjusted hazard ratio, 1.21; 95% CI, 1.02-1.43; and composite end point: adjusted hazard ratio, 1.14; 95% CI, 1.01-1.29, respectively). Conclusions-Presence of DM was independently associated with poor long-term survival outcomes in patients with chronic heart failure
Effect of rosuvastatin in patients with chronic heart failure (the GISSI-HF trial) : a randomised, double-blind, placebo-controlled trial
No full textBackground: Large observational studies, small prospective studies and post-hoc analyses of randomised clinical trials have suggested that statins could be beneficial in patients with chronic heart failure. However, previous studies have been methodologically weak. We investigated the efficacy and safety of the statin rosuvastatin in patients with heart failure. Methods: We undertook a randomised, double-blind, placebo-controlled trial in 326 cardiology and 31 internal medicine centres in Italy. We enrolled patients aged 18 years or older with chronic heart failure of New York Heart Association class II-IV, irrespective of cause and left ventricular ejection fraction, and randomly assigned them to rosuvastatin 10 mg daily (n=2285) or placebo (n=2289) by a concealed, computerised telephone randomisation system. Patients were followed up for a median of 3·9 years (IQR 3·0-4·4). Primary endpoints were time to death, and time to death or admission to hospital for cardiovascular reasons. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00336336. Findings: We analysed all randomised patients. 657 (29%) patients died from any cause in the rosuvastatin group and 644 (28%) in the placebo group (adjusted hazard ratio [HR] 1·00 [95·5% CI 0·898-1·122], p=0·943). 1305 (57%) patients in the rosuvastatin group and 1283 (56%) in the placebo group died or were admitted to hospital for cardiovascular reasons (adjusted HR 1·01 [99% CI 0·908-1·112], p=0·903). In both groups, gastrointestinal disorders were the most frequent adverse reaction (34 [1%] rosuvastatin group vs 44 [2%] placebo group). Interpretation: Rosuvastatin 10 mg daily did not affect clinical outcomes in patients with chronic heart failure of any cause, in whom the drug was safe. Funding: Società Prodotti Antibiotici (SPA; Italy), Pfizer, Sigma Tau, and AstraZeneca
The prevalence of abnormal glucose regulation in patients with coronary artery disease across Europe: The Euro Heart Survey on diabetes and the heart
No full textAim The objective behind the Euro Heart Survey on diabetes and the heart was to study the prevalence of abnormal glucose regulation in adult patients with coronary artery disease (CAD). Methods and results The survey engaged 110 centres in 25 countries recruiting 4196 patients referred to a cardiologist due to CAD out of whom 2107 were admitted on an acute basis and 2854 had an elective consultation. Patient data were collected via a web-based case record form. An oral glucose tolerance test (OGTT) was used for the characterisation of the glucose metabolism. Thirty-one per cent of the patients had diabetes. An OGTT was performed on the 1920 patients without known diabetes, of whom 923 had acute and 997 had a stable manifestation of CAD, respectively. In patients with acute CAD, 36% had impaired glucose regulation and 22% newly detected diabetes. In the stable group these proportions were 37% and 14%. Conclusion This survey demonstrates that normal glucose regulation is less common than abnormal glucose regulation in patients with CAD. OGTT easily discloses the glucometabolic state and should be a routine procedure. The knowledge of glucometabolic state among these patients should influence their future management because it has great potential to improve the outcome
Eco-physiology of Primula farinosa Linn,: and some allied species
No full textEcological and physiological comparisons were made mainly between two populations of Primula farinosa Linn, from northern England and some of their closely related arctic-alpine species:- P. frondosa, P. darialica, P. halleri, P. laurentiana, P. modesta, P. scotica, P. scandinavica, and P. stricta, which have contrasting habitats and natural distribution. The germination of primulas showed a negative or neutral response to the density of seeds sown. They also showed intrinsic seed-dormancy which can be overcome by chilling treatment. Most of the species tested had significantly higher percentage germination in a diurnally fluctuating temperature regime than at 15ºC constant temperature. The results from analyses of leaf characteristics showed significant variation between species studied. Significant correlations were found between chromosome numbers of the species studied and some leaf characteristics, e.g. cell size, stomatal index. Plant growth analyses were investigated along an altitudmal gradient in the north of England. Both vegetative and reproductive growth was clearly affected by microclimate. The primulas showed more sensitive responses to drought than frost as regards to their survival. They responded to water stress by accumulating proline as well as increasing their total protein contents. Photosynthesis measurements showed optimum temperature for O(_2) evolution at warm temperatures of 20-25ºC. The difference in physiological performances of the primulas is discussed in relation to their leaf characteristics, ploidy levels and habitats of origin. This study demonstrates clearly that the two populations of P. farinosa differed in a number of morphological and physiological characteristics; some of which could make it possible for the different races to occupy different ecological habitats
