Toenail selenium concentration and lung cancer in male smokers (Finland)

Background: The objective of this investigation was to evaluate the association between toenail selenium concentration and lung cancer risk in male smokers. Methods: We conducted a nested case–control study within the Alpha–Tocopherol Beta–Carotene Cancer Prevention Study cohort. This substudy included 250 randomly selected incident lung cancer cases and 250 controls matched on age (up to ± 5 years), intervention group assignment, and date or randomization (±15 days). Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using conditional logistic regression methods. Finland began fortification of argricultural fertilizers in the fall of 1984, increasing the dietary intake, plasma, and toenail selenium concentrations for the population. The present analyses were based on the calculated residual of toenail selenium after regressing it on date of randomization. The selenium residual and the interaction of the residual with date of randomization were included in models with smoking status and body mass index as covariates. Results: We observed a suggestion of a protective association for higher selenium status among men who entered the trial early (when the range of selenium values included very low levels). The OR for men with adjusted toenail selenium concentrations at the 75th percentile compared to those with the lowest selenium concentrations ranged between 0.20 (0.09–0.44) for men randomized earliest in the trail and 0.61 (0.27–1.41) for men randomized in the fifth year. Conclusions: These results suggest that low selenium status may be associated with increased risk for lung cancer.     

Long-term effects of rivastigmine in moderately severe Alzheimer's disease: does early initiation of therapy offer sustained benefits?

Goals of the study included evaluating the long-term efficacy of rivastigmine in Alzheimer's disease (AD) patient categories stratified by baseline dementia severity, and post hoc investigation of particular benefits of early initiation of rivastigmine treatment in moderately severe AD. Both rivastigmine-treated groups (originally randomized to 1-4 or 6-12 mg/day) experienced significantly smaller declines in Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) scores from baseline than the projected placebo group after 52 weeks. Patients receiving rivastigmine from Day 1 experienced significantly less decline compared with patients originally receiving placebo and then initiating rivastigmine treatment after a 6-month delay. Furthermore, cognitive benefits were more robust in patients with moderately severe disease compared with previous reports in mild to moderately severe AD. Findings suggest that early treatment with rivastigmine 6-12 mg/day is associated with sustained long-term cognitive benefits in patients with moderately severe AD. The results support the value of early treatment of AD patients, particularly those with moderately severe AD.     

Growth hormone release during acute and chronic aerobic and resistance exercise: recent findings

Exercise is a potent physiological stimulus for growth hormone (GH) secretion, and both aerobic and resistance exercise result in significant, acute increases in GH secretion. Contrary to previous suggestions that exercise-induced GH release requires that a "threshold" intensity be attained, recent research from our laboratory has shown that regardless of age or gender, there is a linear relationship between the magnitude of the acute increase in GH release and exercise intensity. The magnitude of GH release is greater in young women than in young men and is reduced by 4-7-fold in older individuals compared with younger individuals. Following the increase in GH secretion associated with a bout of aerobic exercise, GH release transiently decreases. As a result, 24-hour integrated GH concentrations are not usually elevated by a single bout of exercise. However, repeated bouts of aerobic exercise within a 24-hour period result in increased 24-hour integrated GH concentrations. Because the GH response to acute resistance exercise is dependent on the work-rest interval and the load and frequency of the resistance exercise used, the ability to equate intensity across different resistance exercise protocols is desirable. This has proved to be a difficult task. Problems with maintaining patent intravenous catheters have resulted in a lack of studies investigating alterations in acute and 24-hour GH pulsatile secretion in response to resistance exercise. However, research using varied resistance protocols and sampling techniques has reported acute increases in GH release similar to those observed with aerobic exercise. In young women, chronic aerobic training at an intensity greater than the lactate threshold resulted in a 2-fold increase in 24-hour GH release. The time line of adaptation and the mechanism(s) by which this training effect occurs are still elusive. Unfortunately, there are few studies investigating the effects of chronic resistance training on 24-hour GH release. The decrease in GH secretion observed in individuals who are older or have obesity is associated with many deleterious health effects, although a cause and effect relationship has not been established. While exercise interventions may not restore GH secretion to levels observed in young, healthy individuals, exercise is a robust stimulus of GH secretion. The combination of exercise and administration of oral GH secretagogues may result in greater GH secretion than exercise alone in individuals who are older or have obesity. Whether such interventions would result in favourable clinical outcomes remains to be established.     

Behavioral phenotyping of GFAP-apoE3 and -apoE4 transgenic mice: apoE4 mice show profound working memory impairments in the absence of Alzheimer's-like neuropathology

For the purpose of studying the potential neurobehavioral effects of different human apolipoprotein E (apoE) isoforms produced within the brain, transgenic (TG) mice were generated in which human apoE3 or apoE4 isoforms were under control of an astrocyte-specific, glial fibrillary acidic protein promoter and these TG mice were bred back to apoE knockout (KO) mice. Behavioral phenotypes of apoE3 and apoE4 TG mice were derived by conducting a longitudinal study in which apoE3 and apoE4 TG mice were compared with apoE KO and wild-type (WT) mice (all male) on several behavioral measures. Analysis of locomotor activity, "open-field" behaviors, acoustic startle/prepulse inhibition, and elevated plus maze data suggested that the apoE TG/KO groups were more "emotionally reactive" than WT mice, with apoE4 mice typically being the most reactive. The absence of performance differences among groups on the rotating holeboard and water navigation tasks suggested intact reference memory processing in apoE TG/KO mice. However, apoE4 mice were profoundly impaired on a working memory-based protocol in the radial arm maze (11-14 months). Nonassociative factors (sensorimotor capacities or emotionality differences) did not appear to confound interpretation of the learning/memory results. Western blot analysis revealed no alterations in the level of synaptic, neuronal, or glial markers in neocortex or hippocampus and histologic analysis revealed no evidence of Abeta deposition or neuritic plaques in the apoE KO/TG mice. Our findings suggest that apoE4 expression in the brain may have selective deleterious effects on memory function in the absence of typical Alzheimer's-like neuropathology.     

Response of patients with Alzheimer disease to rivastigmine treatment is predicted by the rate of disease progression

BACKGROUND: Evidence suggests that disease severity predicts the response of patients with Alzheimer disease (AD) to cholinesterase inhibitor treatment, raising the question of whether disease progression also predicts response to this treatment. OBJECTIVE: To evaluate retrospectively whether rate of disease progression during placebo treatment affects response to subsequent rivastigmine tartrate therapy for patients with mild to moderately severe AD. DESIGN: A 26-week, open-label extension study following a 26-week, double-blind, randomized, placebo-controlled trial. SETTING: Outpatient research centers at 22 sites in the United States. PATIENTS: We studied 187 of 235 patients originally randomized to receive placebo treatment in the double-blind phase of the trial who continued with open-label (rivastigmine) extension therapy. INTERVENTION: Placebo treatment for 26 weeks followed by rivastigmine treatment, 2 to 12 mg/d, for 26 weeks. MAIN OUTCOME MEASURES: Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog), Progressive Deterioration Scale, Mini-Mental State Examination, and Global Deterioration Scale scores. RESULTS: Rivastigmine administration during open-label extension therapy benefited patients who had progressed slowly and those who had progressed rapidly during initial double-blind placebo treatment. Slowly progressive patients responded with a mean 1.03-point improvement in the week 26 (ie, start of open-label rivastigmine treatment) ADAS-Cog score at 12 weeks of rivastigmine treatment (week 38 of treatment; P =.02 vs week 26). However, more rapidly progressive patients had a significantly larger mean 4.97-point improvement from the week 26 ADAS-Cog score at 12 weeks (with respect to week 26 of treatment and slowly progressive patient scores, P<.001 for both). Thus, a more rapid disease progression rate while receiving placebo treatment was predictive of a significantly stronger patient response to rivastigmine therapy. This relation also was observed with the other 3 outcome measures and was still apparent when accounting for disease severity. CONCLUSIONS: Rate of disease progression for patients with mild to moderate AD seems to predict response to rivastigmine treatment. Patients with more rapidly progressive disease might be particularly likely to benefit from rivastigmine therapy.     

The use of a bioactive skin substitute decreases length of stay for pediatric burn patients

BACKGROUND: To optimize burn care for children, the authors introduced a protocol incorporating the use of a bioactive skin substitute, TransCyte (Advanced Tissue Sciences, La Jolla, CA). This study was designed to determine whether this management plan was safe, efficacious, and decreased hospital inpatient length of stay (LOS) compared with conventional burn management in children. METHODS: All pediatric burns greater than 7% total body surface area (TBSA) that occurred after October 1999 underwent wound closure with TransCyte (n = 20). These cases were compared with the previous 20 consecutive burn cases greater than 7% TBSA that received standard therapy. Standard therapy consisted of application of antimicrobial ointments and hydrodebridement. The following information was obtained: burn mechanism, age, size of burn, requirement of autograft, and LOS. Data were analyzed using the student's t test. RESULTS: Data for age, percent TBSA burn and LOS are reported as means +/- SEM. The children who received standard therapy were 2.99 +/- 0.7 years compared with those receiving TransCyte were 3.1 +/- 0.8 years. There was no difference between the treatment groups with regard to percent TBSA burn: standard therapy, 14.3 +/- 1.4% TBSA versus TransCyte, 12.7 +/- 1.3% TBSA. There was no difference in the type of burns in each group, the majority were liquid scald type, 70% in the standard therapy group versus 90% in the TransCyte group. Only 1 child in the TransCyte group required autografting (5%) compared with 7 children in the standard therapy group (35%). Children treated with TransCyte had a statistically 6 significant decreaed LOS compared with those receiving standard therapy, 5.9 +/- 0.9 days versus 13.8 +/- 2.2 days, respectively (P =.002). CONCLUSIONS: This is the first study using TransCyte in children. The authors found that this protocol of burn care was safe, effective, and significantly reduced the LOS. This new approach to pediatric burn care is effective and improves the quality of care for children with burns.     

Poorly controlled type 1 diabetes is associated with altered glutathione homeostasis in adolescents: apparent resistance to N‐acetylcysteine supplementation

Blood glutathione concentrations represent a measure of protection against oxidative damage. In earlier studies, we observed that, in adolescents with poorly controlled type 1 diabetes mellitus (T1DM), blood glutathione is significantly depleted because of increased rates of glutathione utilization. To determine whether increased availability of cysteine – one of the three constitutive amino acids of glutathione – would attenuate the alterations in glutathione metabolism, ten 16 ± 1 yr‐old adolescents with poorly controlled T1DM [hemoglobin A1c (HbA1c): 9.9 ± 1.3%] received 5‐h infusions of l ‐[3,3‐²H₂] cysteine and d ‐[6,6‐²H₂]glucose on two occasions, 3 wk apart, after a 10‐d oral supplementation with (i) N‐acetylcysteine (NAC, 30–45 mg/kg/d) or (ii) l ‐alanine, in randomized order, and with a 3‐wk ‘washout’ interim period. Blood glucose was maintained in the same hyperglycemic range on both infusion study days, using intravenous insulin. Glutathione fractional synthesis rate (FSR) was determined from ²H₂‐cysteine incorporation into blood glutathione. NAC supplementation failed to raise erythrocyte cysteine concentrations (23 ± 6 vs. 17 ± 1 μmol/L, p = 0.853) and did not alter erythrocyte glutathione concentrations (838 ± 106 vs. 793 ± 111 μmol/L, p = 0.220) or glutathione FSR (96 ± 20 vs. 89 ± 19%/d, p = 0.974). We conclude that in adolescents with poorly controlled T1DM, dietary cysteine supplementation alone cannot correct glutathione status. In the presence of relative insulinopenia, either higher amino acid doses or aggressive insulin therapy may be needed to achieve this goal. This would require further study.