Nitrous oxide-induced neurological disorders: an increasing public health concern.

BACKGROUND: Neurological presentations resulting from nitrous oxide (N2 O) abuse are increasing in Australia and worldwide. Despite known neuropsychiatric sequelae, N2 O canisters remain readily available and its use unregulated. AIMS: To examine the demographics, clinical and electrophysiological findings of patients presenting with neurological complications of N2 O abuse, and thus inform clinicians and public health decision-makers of the significant public health concerns of this increasing practice. METHODS: Consecutive patients presenting to a tertiary referral metropolitan hospital were included in this series. Patients were identified by a search of discharge summaries of patients admitted with acute or subacute neuropathy or myelopathy and a history of N2 O abuse, and from the electrophysiology database. RESULTS: Thirteen patients were identified, most presenting with subacute paraesthesia, sensory ataxia and lower limb weakness. Eleven had low serum vitamin B12 . Spinal magnetic resonance imaging was consistent with subacute combined degeneration in eight. Nerve conduction studies revealed a motor or sensorimotor axonal neuropathy (three with motor predominance). There was a bimodal demographic distribution consisting of socially isolated, international university students and local residents with a history of mental illness and polydrug abuse. CONCLUSIONS: Recreational N2 O use is an emerging health problem in Australia. International university students and patients with pre-existing mental illness or polydrug use appear to be at increased risk. A severe motor neuropathy may emerge following vitamin B12 replacement. Public health measures are required to limit the availability of N2 O and to educate adolescents and young adults about the potential for significant harm.

Can an automated sleep detection algorithm for waist-worn accelerometry replace sleep logs?

The purpose of this study was to test whether estimates of bedtime, wake time, and sleep period time (SPT) were comparable between an automated algorithm (ALG) applied to waist-worn accelerometry data and a sleep log (LOG) in an adult sample. A total of 104 participants were asked to log evening bedtime and morning wake time and wear an ActiGraph wGT3X-BT accelerometer at their waist for 24 h/day for 7 consecutive days. Mean difference and mean absolute difference (MAD) were computed. Pearson correlations and dependent-sample t tests were used to compare LOG-based and ALG-based sleep variables. Effect sizes were calculated for variables with significant mean differences. A total of 84 participants provided 2+ days of valid accelerometer and LOG data for a total of 368 days. There was no mean difference (p = 0.47) between LOG 472 ± 59 min and ALG SPT 475 ± 66 min (MAD = 31 ± 23 min, r = 0.81). There was no significant mean difference between bedtime (2348 h and 2353 h for LOG and ALG, respectively; p = 0.14, MAD = 25 ± 21 min, r = 0.92). However, there was a significant mean difference between LOG (0741 h) and ALG (0749 h) wake times (p = 0.01, d = 0.11, MAD = 24 ± 21 min, r = 0.92). The LOG and ALG data were highly correlated and relatively small differences were present. The significant mean difference in wake time might not be practically meaningful (Cohen's d = 0.11), making the ALG useful for sample estimates. MAD, which gives a better estimate of the expected differences at the individual level, also demonstrated good evidence supporting ALG individual estimates.

Acute effect of high-intensity cycling exercise on carotid artery hemodynamic pulsatility.

PURPOSE: Investigate the effects of acute high-intensity exercise on common carotid artery (CCA) dimensions, stiffness, and wave intensity. METHODS: Fifty-five healthy men and women (22 ± 5 year; 24.5 ± 2.7 kg m(-2)) underwent 30 s of high-intensity cycling (HIC; Wingate anaerobic test). CCA diameter, stiffness [ß-stiffness, Elastic Modulus (E p)], pulsatility index (PI), forward wave intensities [due to LV contraction (W 1) and LV suction (W 2)], and reflected wave intensity [negative area (NA)] were assessed using a combination of Doppler ultrasound, wave intensity analysis, and applanation tonometry at baseline and immediately post-HIC. RESULTS: CCA ß-stiffness, E p, PI and pulse pressure increased significantly immediately post-HIC (p < 0.05). CCA diameter decreased acutely post-HIC (p < 0.05). There were also significant increases in W 1 and NA and a significant decrease in W 2 (p < 0.05). A significant correlation was found between change in W 1 and PI (r = 0.438, p < 0.05), from rest to recovery as well as a significant inverse correlation between W 2 and PI (r = -0.378, p < 0.05). Change in PI was not associated with change in CCA stiffness or NA (p > 0.05). CONCLUSIONS: Acute HIC results in CCA constriction and increases in CCA stiffness along with increases in hemodynamic pulsatility. The increase in pulsatility may be due to a combination of increased forward wave intensity from increased LV contractility into a smaller vessel (i.e. impaired matching of diameter and flow) coupled with reduced LV suction.

Physical activity offsets the negative effects of a high-fructose diet.

OBJECTIVE: This study aimed to determine the interaction between a high-fructose diet and PA levels on postprandial lipidemia and inflammation in normal-weight, recreationally active individuals. METHODS: Twenty-two men and women (age, 21.2 ± 0.6 yr; body mass index, 22.5 ± 0.6 kg · m(-2)) consumed an additional 75 g of fructose for 14 d on two separate occasions: high physical activity (PA) (approximately 12,500 steps per day) (FR+active) and low PA (approximately 4500 steps per day) (FR+inactive). A fructose-rich test meal was given before and at the end of each intervention. Blood was sampled at baseline and for 6 h after the meal for triglycerides (TG), VLDL, total cholesterol, glucose, insulin, tumor necrosis factor-α, interleukin 6, and C-reactive protein. RESULTS: Log-transformed TG area under the curve (AUC) significantly increased from before (10.1 ± 0.1 mg · dL(-1) × min for 6 h) to after (10.3 ± 0.08 mg · dL(-1) × min for 6 h, P = 0.04) the FR+inactive intervention, with an 88% increase in Δ peak TG (P = 0.009) and an 84% increase in Δ peak VLDL (P = 0.002). Δ Peak interleukin 6 also increased by 116% after the FR+inactive intervention (P = 0.009). Insulin total AUC significantly decreased after FR+active intervention (P = 0.04), with no change in AUC after the FR+inactive intervention. No changes were observed in glucose, tumor necrosis factor-α, and C-reactive protein concentrations (P > 0.05). CONCLUSIONS: Low PA during a period of high fructose intake augments fructose-induced postprandial lipidemia and inflammation, whereas high PA minimizes these fructose-induced metabolic disturbances. Even within a young healthy population, maintenance of high PA (>12,500 steps per day) decreases susceptibility to cardiovascular risk factors associated with elevated fructose consumption.

The effect of intra-uterine growth restriction on blood lipids and response to exercise training.

OBJECTIVES: To determine if a small body size at birth is associated with an unfavorable metabolic profile and a reduced response to exercise training in young adults. METHODS: Thirty-six college students, all singletons born to term, participated. Subjects were defined as either high ponderal index (HIGHPI) or low ponderal index (LOWPI). LOWPI was defined as below the 10th percentile of the PI-for-gestational age distribution. HIGHPI was defined as greater than the 10th percentile. Subject groups were matched pair-wise on age, sex, BMI, and pretraining physical activity level. Subjects completed an 8-week aerobic exercise program. Pre- and post-training measurements included a blood lipid profile. RESULTS: The LOWPI group, when compared to the HIGHPI group, exhibited higher total (183.6 mg dl(-1) vs. 150.9, P = 0.04) and LDL cholesterol (114.8 mg dl(-1) vs. 80.2, P = 0.019) values prior to exercise training. After training, these values decreased in the LOWPI group, eliminating the group difference. Various blood lipid ratios were more favorable for the HIGHPI group, both before and after training. The inclusion of maternal smoking as a covariate attenuated group differences for pretraining TChol, pre-training TG:HDL, and post-training HDL cholesterol. CONCLUSIONS: An 8-week exercise program corrected some, but not all, of the differences in blood lipid values between the LOWPI and HIGHPI group. The persistent group difference in blood lipid ratios suggests a higher long-term risk of chronic disease in the LOWPI group independent of lifestyle intervention.

Activity patterns and perceptions about active transport to school.

OBJECTIVES: To document physical activity patterns and perceptions about active transport to school. METHODS: Children's activity was measured. Children and parents were surveyed about active transport to school. RESULTS: Children were most active after (465 ± 20 cpm) and least active before (379 ± 18 cpm) and during school (351 ± 13 cpm). Weight was not related to activity. Boys were more confident than girls, whereas parents felt more confident than children did about active transport. CONCLUSIONS: Active transport programs will likely have a greater impact on before-school activity than after school. Perceptions concerning active transport should be assessed, and parent/child discrepancies rectified prior to program implementation.