Use of NSE/PS2m-transgenic mice in the study of the protective effect of exercise on Alzheimer's disease

In its late stage, Alzheimer's disease results in progressive muscle weakness in the arms and legs. The aim of this study was to determine whether mice expressing the skeletal muscle-specific mutant PS2 gene (a model of Alzheimer's disease) are a useful experimental system to study the protective effect of exercise on A beta-42 reduction, improvement of behavioural function and changes in metabolic parameters. With this aim in mind, the transgenic mice were subjected to treadmill exercise for 3 months. The results showed that in transgenic mice, but not in normal mice, treadmill exercise resulted in a reduction of A beta-42 deposits and an improvement in behavioural function, thereby restoring normal concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride. Thus, exercise may represent a practical therapeutic strategy for use with human patients with Alzheimer's disease.     

Changes in blood lactate and pyruvate concentrations and the lactate-to-pyruvate ratio during the lactate minimum speed test

The aim of this study was to assess the responses of blood lactate and pyruvate during the lactate minimum speed test. Ten participants (5 males, 5 females; mean +/- s: age 27.1+/-6.7 years, VO2max 52.0+/-7.9 ml x kg(-1) x min(-1)) completed: (1) the lactate minimum speed test, which involved supramaximal sprint exercise to invoke a metabolic acidosis before the completion of an incremental treadmill test (this results in a 'U-shaped' blood lactate profile with the lactate minimum speed being defined as the minimum point on the curve); (2) a standard incremental exercise test without prior sprint exercise for determination of the lactate threshold; and (3) the sprint exercise followed by a passive recovery. The lactate minimum speed (12.0+/-1.4 km x h(-1)) was significantly slower than running speed at the lactate threshold (12.4+/-1.7 km x h(-1)) (P < 0.05), but there were no significant differences in VO2, heart rate or blood lactate concentration between the lactate minimum speed and running speed at the lactate threshold. During the standard incremental test, blood lactate and the lactate-to-pyruvate ratio increased above baseline values at the same time, with pyruvate increasing above baseline at a higher running speed. The rate of lactate, but not pyruvate, disappearance was increased during exercising recovery (early stages of the lactate minimum speed incremental test) compared with passive recovery. This caused the lactate-to-pyruvate ratio to fall during the early stages of the lactate minimum speed test, to reach a minimum point at a running speed that coincided with the lactate minimum speed and that was similar to the point at which the lactate-to-pyruvate ratio increased above baseline in the standard incremental test. Although these results suggest that the mechanism for blood lactate accumulation at the lactate minimum speed and the lactate threshold may be the same, disruption to normal submaximal exercise metabolism as a result of the preceding sprint exercise, including a three- to five-fold elevation of plasma pyruvate concentration, makes it difficult to interpret the blood lactate response to the lactate minimum speed test. Caution should be exercised in the use of this test for the assessment of endurance capacity.     

Correlates of problem recognition and intentions to change among caregivers of abused and neglected children

OBJECTIVE: To identify individual, family, and caseworker characteristics associated with problem recognition (PR) and intentions to change (ITC) in a sample of caregivers who received in-home child welfare services following substantiated reports of child abuse or neglect. METHODS: Caregivers were interviewed at 4 weeks, 16 weeks, and 1 year after referral for in-home services. In these interviews, the University of Rhode Island Change Assessment scale assessed PR and ITC in relation to caregiving practices. Additional data were obtained from administrative records and surveys of in-home services caseworkers. We used growth models to identify caregiver, family, and caseworker characteristics associated with initial levels of PR and ITC, and with changes in PR and ITC over time. RESULTS: Contrary to expectations, there were no overall increases in PR and ITC during the first 4 months of in-home services. PR and ITC scores fluctuated over time, in relation to some external events, case characteristics, and caseworker characteristics; however, we were able to account for small portions of the variance in PR and ITC. Controlling for social desirability bias and other variables in the analysis, negative life events, lack of network support, and the severity of caregiver depression were associated with greater PR; housing problems were associated with lower PR. Caregiver depression and age were associated with ITC. Caregivers whose children had been removed from their homes showed significant increases in ITC in the first few months of in-home services. The duration of caseworkers' child welfare experience predicted increases in their clients' PR in the first 4 months and more frequent contacts with an experienced caseworker predicted small, but significant increases in ITC over time. CONCLUSIONS: PR and ITC are associated with somewhat different case characteristics and may be affected by caseworkers' experience.