10 research outputs found
No more lake balls (Aegagropila linnaei Kützing, Cladophorophyceae, Chlorophyta) in The Netherlands?
Filtering impacts of larval and sessile zebra mussels (Dreissena polymorpha) in western Lake Erie
We assessed the feeding biology of veliger larvae of the introduced zebra mussel (Dreissena polymorpha Pallas) in laboratory experiments using inert microspheres as food analogues. Mean clearance rate on 2.87-μm beads ranged between 247 and 420 μL veliger-1 day-1. Clearance rate was unrelated to bead concentration up to 100 beads μL-1, but was positively correlated with veliger shell length. Clearance rates of Dreissena veligers are within the range of those reported for marine bivalve veligers of similar size and for herbivorous Great Lakes microzooplankton, but are orders of magnitude lower than those of settled, conspecific adults. The impact of settled zebra mussel grazing activities on phytoplankton stocks may be up to 1162 times greater than that exerted by veliger populations in western Lake Erie. Based on 1990 size-frequency distributions and associated literature-derived clearance rates, reef-associated Dreissena populations in western Lake Erie (mean depth ∼7 m) possess a tremendous potential to filter the water column (up to 132 m3 m-2 day-1) and redirect energy from pelagic to benthic foodwebs. Preliminary analyses indicate that chlorophyll a concentration is strongly depleted (\u3c1 μg L-1) above Dreissena beds in western Lake Erie. © 1992 Springer-Verlag
Filtering impacts of larval and sessile zebra mussels (Dreissena polymorpha) in western Lake Erie
Influence of food size and food quantity on the feeding of the mussel Dreissena polymorpha
Development of a definition for Rapid Progression (RP) of renal function in HIV-positive persons: The D:A:D study
Background: No consensus exists on how to define abnormally rapid deterioration in renal function (Rapid Progression, RP). We developed an operational definition of RP in HIV-positive persons with baseline estimated glomerular filtration rate (eGFR) >90 ml/min/1.73 m2 (using Cockcroft Gault) in the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study from 2004 to 2011. Methods. Two definitions were evaluated; RP definition A: An average eGFR decline (slope) ≥5 ml/min/1.73 m 2/year over four years of follow-up with ≥3 eGFR measurements/year, last eGFR <90 ml/min/1.73 m2 and an absolute decline ≥5 ml/min/1.73 m2/year in two consecutive years. RP definition B: An absolute annual decline ≥5 ml/min/1.73 m2/year in each year and last eGFR <90 ml/min/1.73 m2. Sensitivity analyses were performed considering two and three years' follow-up. The percentage with and without RP who went on to subsequently develop incident chronic kidney disease (CKD; 2 consecutive eGFRs <60 ml/min/1.73 m2 and 3 months apart) was calculated. Results: 22,603 individuals had baseline eGFR ≥90 ml/min/1.73 m2. 108/3655 (3.0%) individuals with ≥4 years' follow-up and ≥3 measurements/year experienced RP under definition A; similar proportions were observed when considering follow-up periods of three (n=195/6375; 3.1%) and two years (n=355/10756; 3.3%). In contrast under RP definition B, greater proportions experienced RP when considering two years (n=476/10756; 4.4%) instead of three (n=48/6375; 0.8%) or four (n=15/3655; 0.4%) years' follow-up. For RP definition A, 13 (12%) individuals who experienced RP progressed to CKD, and only (21) 0.6% of those without RP progressed to CKD (sensitivity 38.2% and specificity 97.4%); whereas for RP definition B, fewer RP individuals progressed to CKD. Conclusions: Our results suggest using three years' follow-up and at least two eGFR measurements per year is most appropriate for a RP definition, as it allows inclusion of a reasonable number of individuals and is associated with the known risk factors. The definition does not necessarily identify all those that progress to incident CKD, however, it can be used alongside other renal measurements to early identify and assess those at risk of developing CKD. Future analyses will use this definition to identify other risk factors for RP, including the role of antiretrovirals. © 2014 Kamara et al.; licensee BioMed Central Ltd
Variable impact on mortality of AIDS-defining events diagnosed during combination antiretroviral therapy: not all AIDS-defining conditions are created equal.
Abstract
Background—The extent to which mortality differs following individual acquired
immunodeficiency syndrome (AIDS)–defining events (ADEs) has not been assessed among
patients initiating combination antiretroviral therapy.
Methods—We analyzed data from 31,620 patients with no prior ADEs who started combination
antiretroviral therapy. Cox proportional hazards models were used to estimate mortality hazard
ratios for each ADE that occurred in >50 patients, after stratification by cohort and adjustment for
sex, HIV transmission group, number of anti-retroviral drugs initiated, regimen, age, date of
starting combination antiretroviral therapy, and CD4+ cell count and HIV RNA load at initiation
of combination antiretroviral therapy. ADEs that occurred in <50 patients were grouped together
to form a “rare ADEs” category.
Results—During a median follow-up period of 43 months (interquartile range, 19–70 months),
2880 ADEs were diagnosed in 2262 patients; 1146 patients died. The most common ADEs were
esophageal candidiasis (in 360 patients), Pneumocystis jiroveci pneumonia (320 patients), and
Kaposi sarcoma (308 patients). The greatest mortality hazard ratio was associated with non-
Hodgkin’s lymphoma (hazard ratio, 17.59; 95% confidence interval, 13.84–22.35) and progressive
multifocal leukoencephalopathy (hazard ratio, 10.0; 95% confidence interval, 6.70–14.92). Three
groups of ADEs were identified on the basis of the ranked hazard ratios with bootstrapped
confidence intervals: severe (non-Hodgkin’s lymphoma and progressive multifocal
leukoencephalopathy [hazard ratio, 7.26; 95% confidence interval, 5.55–9.48]), moderate
(cryptococcosis, cerebral toxoplasmosis, AIDS dementia complex, disseminated Mycobacterium
avium complex, and rare ADEs [hazard ratio, 2.35; 95% confidence interval, 1.76–3.13]), and
mild (all other ADEs [hazard ratio, 1.47; 95% confidence interval, 1.08–2.00]).
Conclusions—In the combination antiretroviral therapy era, mortality rates subsequent to an
ADE depend on the specific diagnosis. The proposed classification of ADEs may be useful in
clinical end point trials, prognostic studies, and patient management
Variable impact on mortality of AIDS-defining events diagnosed during combination antiretroviral therapy: not all AIDS-defining conditions are created equal
Abstract
Background—The extent to which mortality differs following individual acquired
immunodeficiency syndrome (AIDS)–defining events (ADEs) has not been assessed among
patients initiating combination antiretroviral therapy.
Methods—We analyzed data from 31,620 patients with no prior ADEs who started combination
antiretroviral therapy. Cox proportional hazards models were used to estimate mortality hazard
ratios for each ADE that occurred in >50 patients, after stratification by cohort and adjustment for
sex, HIV transmission group, number of anti-retroviral drugs initiated, regimen, age, date of
starting combination antiretroviral therapy, and CD4+ cell count and HIV RNA load at initiation
of combination antiretroviral therapy. ADEs that occurred in <50 patients were grouped together
to form a “rare ADEs” category.
Results—During a median follow-up period of 43 months (interquartile range, 19–70 months),
2880 ADEs were diagnosed in 2262 patients; 1146 patients died. The most common ADEs were
esophageal candidiasis (in 360 patients), Pneumocystis jiroveci pneumonia (320 patients), and
Kaposi sarcoma (308 patients). The greatest mortality hazard ratio was associated with non-
Hodgkin’s lymphoma (hazard ratio, 17.59; 95% confidence interval, 13.84–22.35) and progressive
multifocal leukoencephalopathy (hazard ratio, 10.0; 95% confidence interval, 6.70–14.92). Three
groups of ADEs were identified on the basis of the ranked hazard ratios with bootstrapped
confidence intervals: severe (non-Hodgkin’s lymphoma and progressive multifocal
leukoencephalopathy [hazard ratio, 7.26; 95% confidence interval, 5.55–9.48]), moderate
(cryptococcosis, cerebral toxoplasmosis, AIDS dementia complex, disseminated Mycobacterium
avium complex, and rare ADEs [hazard ratio, 2.35; 95% confidence interval, 1.76–3.13]), and
mild (all other ADEs [hazard ratio, 1.47; 95% confidence interval, 1.08–2.00]).
Conclusions—In the combination antiretroviral therapy era, mortality rates subsequent to an
ADE depend on the specific diagnosis. The proposed classification of ADEs may be useful in
clinical end point trials, prognostic studies, and patient management