Ecosystem effects of thermal manipulation of a whole lake, Lake Breisjøen, southern Norway (THERMOS project)

International audienceWe conducted a 3-year artificial deepening of the thermocline in the dimictic Lake Breisjøen, southern Norway, by means of a large submerged propeller. An adjacent lake served as untreated reference. The manipulation increased thermocline depth from 6 to 20 m, caused a significant increase in the heat content, and delayed ice-on by about 20 days. There were only minor changes in water chemistry. Concentrations of sulphate declined, perhaps due to greater reduction of sulphate at the sediment-water interface. Concentrations of particulate carbon and nitrogen decreased, perhaps due to increased sedimentation velocity. Water transparency increased. There was no significant change in concentration of phosphorus, the growth-limiting nutrient. There were few significant changes in principal biological components. Phytoplankton biomass and productivity did not change, although the chlorophyll-a concentration showed a small decrease. Phytoplankton species richness increased, and the species composition shifted. Growth of periphyton increased. There was no change in the macrophyte community. The manipulation did not affect the zooplankton biodiversity, but caused a significant shift in the relative abundance (measured as biomass) in the two major copepod species. The manipulation did not affect the individual density, but appeared to have changed the vertical distribution of zoobenthos. Fish populations were not affected. The lake is oligotrophic and clearwater and the manipulation did not change the supply of phosphorus, and thus there were only minor changes in lake chemistry and biology. Effects might be larger in eutrophic and dystrophic lakes in which internal processes are stronger

Prevalence, awareness, treatment, and control rate of hypertension in HIV-infected patients: the HIV-HY study

Background: We aimed to assess the prevalence of hypertension in an unselected human immunodeficiency virus (HIV)–infected population and to identify factors associated with hypertension prevalence, treatment, and control. Methods: We used a multicenter, cross-sectional, nationwide study that sampled 1,182 unselected, consecutive, HIV-infected patients. Office blood pressure was accurately measured with standard procedures. Results: Patients were 71% men and 92% white, with a median age of 47 years (range = 18–78); 6% were antiretroviral treatment naive. The overall prevalence of hypertension was 29.3%; high-normal pressure accounted for an additional 12.3%. Among hypertensive subjects, 64.9% were aware of their hypertensive condition, 52.9% were treated, and 33.0% were controlled (blood pressure < 140/90mm Hg). Blood pressure–lowering medications were used in monotherapy in 54.3% of the subjects. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers were the most frequently used drugs (76.1%: monotherapy = 39.1%, combination treatment = 37.0%). In multivariable regression models, hypertension was independently predicted by traditional risk factors, including age ≥50 years, male sex, family history of cardiovascular disease, body mass index ≥25kg/m2, previous cardiovascular events, diabetes, central obesity, and metabolic syndrome, as well as by duration of HIV infection, duration of antiretroviral therapy, and nadir CD4+ T-cell count <200/µl. The choice of protease inhibitors vs. nonnucleoside reverse transcriptase inhibitors as a third antiretroviral drug was irrelevant. Conclusions: Hypertension affects nearly 30% of HIV adult outpatients in Italy. More than one-third of the hypertensive subjects are unaware of their condition, and more than two-thirds are uncontrolled. A higher level of attention to the diagnosis and treatment of hypertension is mandatory in this setting