Phosphate supplementation, cardiovascular function, and exercise performance in humans

The use of oral phosphate (Pi) supplements to improve muscular work performance has long been proposed without substantiating data. In a double-blind, crossover experiment 11 male runners ingested calcium Pi (176 mmol/day) or placebo for 4 days. On the 3rd treatment day, subjects ran an incremental maximal aerobic capacity test (VO2 max) on a treadmill, and on the 4th day a treadmill run to exhaustion at approximately 70% VO2max. By the 4th day of Pi loading, plasma Pi was significantly higher than control (P less than 0.05); however, erythrocyte Pi, 2,3-diphosphoglycerate, and O2 half-saturation pressure of hemoglobin (P50) were not elevated. VO2 max was not changed by the treatments (mean 62.9, 64.2, 64.9 ml.kg-1.min-1 for control, Pi, and placebo bouts, respectively) nor was submaximal run time to exhaustion (61.6 min for Pi, 65.5 min for placebo). Stroke volume at steady-state VO2 was decreased with Pi (P less than 0.05), whereas cardiac output tended (P = 0.07) to be lower. Greater arteriovenous O2 difference (P less than 0.05) with Pi suggested a peripheral effect that increased O2 extraction. We concluded that in healthy individuals Pi loading produced no improvement in work tolerance or aerobic capacity but did alter some aspects of cardiovascular function.     

Comparison of DNA facilitators in the uptake and intracellular fate of infectious herpes simplex virus type 2 DNA.

The comparative efficiencies of polyornithine, CaCl2 and DEAE-dextran in enhancing the infectivity of exogenous herpes simplex virus (HSV) type 2 DNA were examined. CaCl2 was 12-times more effective in promoting genetic expression of viral DNA than DEAE-dextran, while polyornithine did not mediate any HSV DNA infectivity. A comparison of sedimentation profiles of DNA extracted from cells inoculated with viral DNA in the presence of each facilitator revealed that input 56 S HSV DNA underwent marked alteration with time. There was also extensive processing of a 20 S DNA species. The data indicated that the biological efficiency of each facilitator was related to the amount of 20 S DNA remaining at the final time periods. One possible explanation for the efficiency of CaCl2 as a facilitator was that it allowed for the reutilization of the 20 S DNA species during HSV replication. The persistence of the 20 S peak in cells treated with DEAE-dextran was a measure of the decreased efficacy of this facilitator. Finally, the absence of a 56 S peak and the greatly elevated levels of 20 S DNA at final time points in polyornithine-treated cells accounted for the failure of this compound to promote HSV DNA infectivity.     

Modulation of calcium by the carcinogenic process in the liver induced by a choline-deficient diet

A diet devoid of choline and low in methionine (CD), without any added carcinogen, has been shown to induce 100% preneoplastic nodules and more than 50% cancer in the rat liver. Attempts to understand the mechanism by which a CD diet induces liver cell cancer revealed that like chemical carcinogens, a CD diet also appears to cause alterations in DNA, perhaps mediated by free radicals. Indeed, a CD diet induces nuclear lipid peroxidation prior to the changes in DNA. The CD diet induced DNA alterations coupled with continuing liver cell proliferation may account for the induction of initiated hepatocytes by the CD diet. To gain insight into the nature of free radicals generated by the CD diet, experiments were designed to determine whether agents that modulate free radical effects influence the CD diet induced changes in the liver. We investigated the effect of Ca2+ in the modulation of CD diet induced alterations in the liver. The results show that extra Ca2+ when added to the CD diet prevented some of the early changes due to choline deficiency, such as nuclear lipid peroxidation and DNA damage, but had little or no effect on the triglyceride accumulation in the liver. Also, the same CD diet with extra Ca2+, when used as a promoter after initiation by diethylnitrosamine, decreased the number and size of early putative preneoplastic foci and nodules.     

Happy Art

This article looks at how arts integration can boost the language development of limited English proficient students in kindergarten through second grade. I first review existing research on how young children learn and describe the special challenges faced by children who must learn in an unfamiliar language. I then identify arts-based mechanisms that boost the language development of limited English proficient students and examine strategies used by a successful urban arts-and-literacy program to enhance the language development of English language learners in the primary grades.     

Polypharmacy in the management of patients with schizophrenia on risperidone in a tertiary-care hospital in Malaysia

The present study was conducted primarily to determine the occurrence of polypharmacy in patients with schizophrenia on risperidone. The secondary aim was to ascertain the incidence of inappropriate prescribing with anticholinergics. A retrospective review of the medical records of all patients who were being followed up at the out-patient clinic of a tertiary-care hospital in Malaysia was conducted. Only patients who were being prescribed risperidone between 1 June 2008 and 31 December 2008 were included in the study. Demographic data such as patient’s age, gender and race were obtained from the patient’s medical records. In total, 113 patients met the selection criteria. Polypharmacy was found to occur in 34 patients (30.09%), with the majority (76.47%) being on two antipsychotics. In total, 27 patients (34.18%) on monotherapy with risperidone were prescribed an anticholinergic on scheduled dosing, while 19 patients (24.05%) were prescribed it on an as-needed basis. Of the patients on polypharmacy, 26 (76.47%) were on scheduled dosing of anticholinergics, while three (8.82%) were taking the medication on an as-needed basis. Polypharmacy should be avoided, and the use of anticholinergics should be closely reviewed. By adopting more efficient prescribing practices, costs can be reduced and financial resources can instead be channelled towards more beneficial areas for the patients.