A Recurrent Network Model of Somatosensory Parametric Working Memory in the Prefrontal Cortex

Cerebral Cortex November     

Challenges for nephrology nurses in the management of children with chronic kidney disease.

An important treatment goal for pediatric nephrology caregivers is the optimization of a child's capacity for normal growth and development. However, the physiologic and metabolic derangements associated with chronic kidney disease (CKD) significantly alter these processes, creating important challenges in the care of affected children. Evidence-based clinical practice guidelines support early recognition and treatment of CKD-related complications to improve growth and development and, ultimately, quality of life for children with this chronic condition.     

Measurement of leptin in dried blood spot samples.

Leptin is important in a wide range of physiological processes, but logistical constraints associated with venipuncture blood collection have limited research on leptin in diverse, community-based settings. The aim of this short report is to present and validate an enzyme immunoassay method for quantifying leptin in samples of capillary whole blood collected from a simple finger prick and dried on filter paper. The method was evaluated through analysis of precision, reliability, stability, and comparisons with matched plasma and blood spot samples. We report acceptable levels of assay precision and reliability, and good agreement between results obtained from matched plasma and blood spot samples (r = 0.976, P < 0.001). Leptin concentrations begin to deteriorate after only 3 days at room temperature. Thus, care should be taken to refrigerate or freeze samples promptly. The relative ease of blood spot sample collection may facilitate research on leptin in a wider range of cultural and ecological settings.     

Effects of exercise on muscle activation and metabolism in multiple sclerosis

We investigated the role of metabolism in muscle fatigue during voluntary exercise in persons with mild multiple sclerosis (MS). Six MS and 8 healthy control subjects performed intermittent, progressive, isometric contractions of the ankle dorsiflexors, during which we measured maximum voluntary force (MVC), inorganic phosphate (Pi), phosphocreatine (PCr), and pH. During exercise. MVC fell sooner in MS, but by the end of exercise the relative decrease in MVC was similar in both groups. In contrast, at the end of exercise Pi/PCr increased to 1.86 ± 0.22 in controls but to only 0.66 ± 0.04 in MS (P < 0.01); likewise, pH was 6.75±0.04 in controls and unchanged (7.06 ± 0.04) in MS (P <0.01). The smaller metabolic change at the same relative exercise intensity suggests a failure of muscle activation that is present even in mild MS. Neurophsyiologic measures of activation indicated some central activation failure and no neuromuscular junction impairment in MS, and suggested that activation failure beyond the muscle membrane(excitation–contraction coupling) may be important in MS. We conclude that metabolic factors do not play a significant role in the development of muscle fatigue during voluntary exercise in mild MS. © 1994 John Wiley & Sons, Inc.