Causes and Consequences of Intraspecific Variation in Behavior of the Red Imported Fire Ant

Organisms vary at the individual and population level in many ecologically relevant traits. This study documents and quantifies colony-level variation in ecologically important behaviors of a widespread invasive social insect, demonstrates multitrophic ecological effects of this colony-level variation, and explores genetic factors that may affect and predict behavior at the colony-level. I quantified significant, persistent regional and colony-level variation in the red imported fire ant (Solenopsis invicta) in behaviors such as extra-nest activity, exploration, and resource discovery speed and recruitment effort. Colony behavior correlated with both colony productivity and colony growth. Using single-lineage colonies, I estimated broad-sense heritability of between 0.45 and 0.5 for the observed colony behaviors. I created experimental microcosms comprised of fire ant colonies, plants, and insect herbivores. Differences in fire ant colony behavior linked to carbohydrate attraction directly impacted herbivore mortality and indirectly impacted plant damage. I quantified colony differences colony differences in the expression of the fire ant foraging gene (sifor) as well as colony-level differences in behavior for fire ant colonies collected from across a large area of Texas. Expression of sifor was more than three-fold higher in fire ant foragers than in fire ant workers in the interior of the nest, and colony-level differences in sifor expression of foragers and interior workers correlated with colony behavior. Higher sifor expression in foragers correlated with higher foraging activity, exploratory activity, and recruitment to nectar in fire ant colonies. Finally, I explored the hypothesis that fire ant foundress groups could maximize inclusive fitness benefits and alter cooperative and competitive behaviors in response to cues indicating higher relatedness of foundresses. I found that group and queen performance was significantly affected by group composition. Groups composed of foundresses that were less likely to be related produced no more workers than queens founding alone, while groups composed of foundresses from the same site produced the most workers of all group types. The conclusions of this study have widespread implications for many social insects and their ecological interactions. By further exploring these effects at the mechanistic, organismal, and ecological level we will improve our understanding of collective behavior, social evolution, and intraspecific variation

Severe dialyzer dysfunction undetectable by standard reprocessing validation tests

Severe dialyzer dysfunction undetectable by standard reprocessing validation tests. It is generally accepted that careful monitoring of total cell volume and ultrafiltration rates will ensure adequate function of reprocessed dialyzers. During routine urea kinetic measurements we noted that the percent of patients with clearances less than 200ml/min increased from 5% to 48% despite adherence to these validation tests. As these patients did not have evidence of recirculation in the vascular access, possible causes of dialyzer dysfunction were investigated. Injection of methylene blue into the dialysate port revealed non-uniform flow of dialysate in dialyzers from patients with markedly reduced clearances. In vitro studies of dialyzers subjected to sequential daily reprocessing, without patient exposure, demonstrated that in vitro clearances declined in one lot but not another. The initial clearances of 218 ± 4ml/min fell progressively to 112 ± 18 (P < 0.001) after 15 reuses. No effects of reprocessing were found in a different lot (230 ± 2 vs. 226 ± 4 ml/min). Soaking the dialyzers from the affected lot in either the disinfectant or dialysate solution caused a decline in the clearances which was less than that of serial reuse. Although the magnitude of the problem of dialyzer malfunction with reuse is unknown, careful attention to dialyzer function is warranted in patients treated with reprocessed dialyzers

Relationship between volume status and blood pressure during chronic hemodialysis

Relationship between volume status and blood pressure during chronic hemodialysis.BackgroundThe relationship between volume status and blood pressure (BP) in chronic hemodialysis (HD) patients remains incompletely understood. Specifically, the effect of interdialytic fluid accumulation (or intradialytic fluid removal) on BP is controversial.MethodsWe determined the association of the intradialytic decrease in body weight (as an indicator of interdialytic fluid gain) and the intradialytic decrease in plasma volume (as an indicator of postdialysis volume status) with predialysis and postdialysis BP in a cross-sectional analysis of a subset of patients (N = 468) from the Hemodialysis (HEMO) Study. Fifty-five percent of patients were female, 62% were black, 43% were diabetic and 72% were prescribed antihypertensive medications. Dry weight was defined as the postdialysis body weight below which the patient developed symptomatic hypotension or muscle cramps in the absence of edema. The intradialytic decrease in plasma volume was calculated from predialysis and postdialysis total plasma protein concentrations and was expressed as a percentage of the plasma volume at the beginning of HD.ResultsPredialysis systolic and diastolic BP values were 153.1 ± 24.7 (mean ± SD) and 81.7 ± 14.8mm Hg, respectively; postdialysis systolic and diastolic BP values were 136.6 ± 22.7 and 73.9 ± 13.6mm Hg, respectively. As a result of HD, body weight was reduced by 3.1 ± 1.3kg and plasma volume was contracted by 10.1 ± 9.5%. Multiple linear regression analyses showed that eachkg reduction in body weight during HD was associated with a 2.95mm Hg (P = 0.004) and a 1.65mm Hg (P = NS) higher predialysis and postdialysis systolic BP, respectively. In contrast, each 5% greater contraction of plasma volume during HD was associated with a 1.50mm Hg (P = 0.026) and a 2.56mm Hg (P < 0.001) lower predialysis and postdialysis systolic BP, respectively. The effects of intradialytic decreases in body weight and plasma volume were greater on systolic BP than on diastolic BP.ConclusionsHD treatment generally reduces BP, and these reductions in BP are associated with intradialytic decreases in both body weight and plasma volume. The absolute predialysis and postdialysis BP levels are influenced differently by acute intradialytic decreases in body weight and acute intradialytic decreases in plasma volume; these parameters provide different information regarding volume status and may be dissociated from each other. Therefore, evaluation of volume status in chronic HD patients requires, at minimum, assessments of both interdialytic fluid accumulation (or the intradialytic decrease in body weight) and postdialysis volume overload

A randomized, crossover design study of sevelamer carbonate powder and sevelamer hydrochloride tablets in chronic kidney disease patients on haemodialysis

Background. Sevelamer carbonate is an improved, buffered form of sevelamer hydrochloride developed for the treatment of hyperphosphataemia in CKD patients. Sevelamer carbonate formulated as a powder for oral suspension presents a novel, patient-friendly alternative to tablet phosphate binders. This study compared the safety and efficacy of sevelamer carbonate powder with sevelamer hydrochloride tablets in CKD patients on haemodialysis

Carpal Tunnel Syndrome and Peripheral Polyneuropathy in Patients with End Stage Kidney Disease

This study was designed to identify the causes of the development of carpal tunnel syndrome (CTS) associated with end stage kidney disease (ESKD). A total of 112 patients with ESKD, 64 on hemodialysis (HD) and 48 on peritoneal dialysis (PD), were enrolled. The duration of ESKD and dialysis, the site of the arteriovenous (A-V) fistula for HD, laboratory data such as blood urea nitrogen, creatinine, and beta-2-microglobulin were determined. Clinical evaluation of CTS and electrophysiological studies for the diagnosis of CTS and peripheral neuropathy were performed. The electrophysiological studies showed that the frequency of CTS was not different in the HD and PD groups (P = 0.823) and the frequency of CTS was not different in the limb with the A-V fistula compared to the contralateral limb (P = 0.816). The frequency of HD and PD were not related to beta-2-microglobulin levels, an indicator of amyloidosis. The frequency of CTS did not increase as the severity of the peripheral neuropathy and the duration of ESKD and dialysis increased (P = 0.307). The results of this study do not support that microglobulin induced amyloidosis or placement of an A-V fistula are associated with an increase in CTS

Evaluation of calcium acetate/magnesium carbonate as a phosphate binder compared with sevelamer hydrochloride in haemodialysis patients: a controlled randomized study (CALMAG study) assessing efficacy and tolerability

Background. Phosphate binders are required to control serum phosphorus in dialysis patients. A phosphate binder combining calcium and magnesium offers an interesting therapeutic option

What is new in uremic toxicity?

Uremic syndrome results from a malfunctioning of various organ systems due to the retention of compounds which, under normal conditions, would be excreted into the urine and/or metabolized by the kidneys. If these compounds are biologically active, they are called uremic toxins. One of the more important toxic effects of such compounds is cardio-vascular damage. A convenient classification based on the physico-chemical characteristics affecting the removal of such compounds by dialysis is: (1) small water-soluble compounds; (2) protein-bound compounds; (3) the larger “middle molecules”. Recent developments include the identification of several newly detected compounds linked to toxicity or the identification of as yet unidentified toxic effects of known compounds: the dinucleotide polyphosphates, structural variants of angiotensin II, interleukin-18, p-cresylsulfate and the guanidines. Toxic effects seem to be typically exerted by molecules which are “difficult to remove by dialysis”. Therefore, dialysis strategies have been adapted by applying membranes with larger pore size (high-flux membranes) and/or convection (on-line hemodiafiltration). The results of recent studies suggest that these strategies have better outcomes, thereby clinically corroborating the importance attributed in bench studies to these “difficult to remove” molecules