Feasibility of cochlear implantation in Mucopolysaccharidosis.

UNLABELLED: Mucopolysaccharidoses (MPS) are a group of rare inherited metabolic disorders resulting from deficiencies of particular enzymes involved in the breakdown of glycosaminoglycans. Amongst the manifestations of MPS within the head and neck patients may develop conductive, mixed or sensorineural hearing loss. OBJECTIVE: The main objective of this paper is to describe the management of profound sensorineural hearing loss in children with Mucopolysaccaridosis. The primary outcome measures for this case series were improvement in auditory performance and speech perception scores following cochlear implantation. Secondary outcome measures included surgical complications. METHODS: We carried out a casenote review of the first two cases of cochlear implantation (CI) to rehabilitate profound sensory neural hearing loss in Mucopolysaccharidoses. Improvement in auditory performance was measured by categories of auditory performance (CAP) score, speech reception score (SRS) and the IHR McCormick toy discrimination test. RESULTS: Both patients with MPS had demonstrable benefit from CI in terms of auditory performance and speech perception. The first patient improved from pre-operatively only managing to recognise environmental sounds to understanding conversation without lip-reading with a familiar talker. Following CI, the second patient can discriminate speech in noisy environments to a degree, without lip-reading. No peri-operative complications were noted in either patient. CONCLUSION: As the medical management of the MPS has progressed there is likely to be a corresponding increase in survival. This increased life-expectancy will likely lead to greater numbers of patients with MPS surviving long enough to develop profound hearing loss. Likewise, when considering the risks and benefits of quality of life interventions such as CI in patients with MPS, it is more likely that the risks of surgery and general anaesthesia will be considered acceptable. Clinicians managing such patients will need to be aware of these developments.

Effect of the alpha-gamma phase transition on the stability of dislocation loops in bcc iron.

Body-centered-cubic iron develops an elastic instability, driven by spin fluctuations, near the alpha-gamma phase transition temperature T(c) = 912 degrees C that is associated with the dramatic reduction of the shear stiffness constant c' (c(11)-c(12))/2 near T(c). This reduction of c' has a profound effect on the temperature dependence of the anisotropic elastic self-energies of dislocations in iron. It also affects the relative stability of the a[100] and a/2[111] prismatic edge dislocation loops formed during irradiation. The difference between the anisotropic elastic free energies provides the fundamental explanation for the observed dominant occurrence of the a[100], as opposed to the a/2[111], Burgers vector configurations of prismatic dislocation loops in iron and iron-based alloys at high temperatures.

Interaction of acute changes in exercise energy expenditure and energy intake on resting metabolic rate.

The effects on resting metabolic rate (RMR) of energy intake and exercise energy expenditure were examined in eight trained men under four conditions: 1) high energy flux (HF), 90 min of exercise at 75% VO2max on 3 d while in energy balance; 2) low energy flux (LF), no exercise for 3 d while in energy balance; 3) negative energy balance (NEB), exercise on 3 d while consuming low-flux meals; and 4) positive energy balance (PEB), no exercise for 2 d while consuming high-flux meals. Eight untrained men were studied in LF. There were effects of exercise energy expenditure and energy intake on RMR, and an exercise x diet interaction (P < 0.05). RMR was greater in trained than in untrained subjects only when trained subjects were in HF. These data indicate that RMR is influenced by exercise, energy intake, and their interaction and suggest that higher RMR in trained vs untrained individuals results from acute effects of HF rather than from a chronic adaptation to exercise training.

Postexercise energy expenditure in response to acute aerobic or resistive exercise.

Postexercise energy metabolism was examined in male subjects age 22-35 years in response to three different treatments: a strenuous bout of resistive exercise (REx), a bout of stationary cycling (AEx) at 50% peak VO2, and a control condition (C) of quiet sitting. Resting metabolic rate (RMR) was measured the morning of and the morning following each condition. Recovery oxygen consumption (RcO2) was measured for 5 hr following each treatment. Total 5-hr RcO2 was higher for the REx treatment relative to both AEx and C, with the largest treatment differences occurring early during recovery. There were no large treatment differences in postexercise respiratory exchange ratio values, except for the first hour of recovery following REx. RMR measured 14.5 hr postexercise for the REx condition was significantly elevated compared to C. These results suggest that strenuous resistive exercise results in a greater excess postexercise oxygen consumption compared to steady-state endurance exercise of similar estimated energy cost.

Effect of acute resistance exercise on postexercise energy expenditure and resting metabolic rate.

Two separate experiments were performed to determine the effect of acute resistive exercise on postexercise energy expenditure in male subjects previously trained in resistive exercise. In experiment 1, after measurement of their resting metabolic rate (RMR) at 0700 h and their ingestion of a standardized meal at 0800 h, seven subjects (age range 22-40 yr) beginning at 1400 h completed a 90-min weight-lifting protocol. Postexercise metabolic rate (PEMR) was measured continuously for 2 h after exercise and compared with a preexercise baseline. RMR was measured the following morning 15 h after completion of the workout. In experiment 2, six different men (age range 20-35 yr) completed a similar experimental protocol as well as a control condition on a separate day in which metabolic rate was measured for 2 h after a period of quiet sitting. For both experiments, PEMR remained elevated for the entire 2-h measured recovery period, with the average oxygen consumption for the last 6 min elevated by 11-12%. RMR measured the morning after exercise was 9.4% higher in experiment 1 and 4.7% higher in experiment 2 than on the previous day. In experiment 2, the postabsorptive respiratory exchange ratio was significantly lower the morning after the exercise bout. Strenuous resistive exercise may elevate PEMR for a prolonged period and may enhance postexercise lipid oxidation.

Resting metabolic rate and postprandial thermogenesis by level of aerobic fitness in young women.

Resting metabolic rate (RMR) and the thermic effect of a meal (TEM) were compared among women of three levels of aerobic fitness. Twenty-three euthyroid, eumenorrheic women (aged 18-35 years) were divided into three groups based on VO2 max standardized for fat-free weight (FFW), as determined from a graded exercise test: High Fit (HF): n = 7, VO2 max > 70 ml*kg FFW-1*min-1; Moderately Fit (MF): n = 8, VO2 max = 55-70 ml*kg FFW-1*min-1; and Low Fit (LF): n = 8, VO2 max < 55 ml*kg FFW-1*min-1). At 0700h RMR was measured for 1 h by indirect calorimetry with subjects in a fasted, preovulatory state, having refrained from exercise on the preceding day. The subject then consumed a liquid meal (12 kcal*kg FFW-1) and indirect calorimetry was continued for 3 h to determine the TEM. RMR adjusted for FFW using analysis of covariance was significantly higher (P < 0.05) in the HF group (mean +/- SEM = 1.08 +/- 0.03 kcal*min-1) compared to the MF (0.99 +/- 0.04) and LF (0.90 +/- 0.04) groups. Group differences in the thermic response did not reach statistical significance, although there was a trend for a high TEM in the HF group. There was a positive relationship between RMR and energy flux (average daily kcalorie intake + daily kcaloric expenditure in physical activity). These results suggest that women who exhibit high levels of exercise and aerobic fitness may be less energy efficient during the non-exercise portion of the day then their less active counterparts.

Effect of inpatient versus outpatient measurement protocol on resting metabolic rate and respiratory exchange ratio.

Resting metabolic rate (RMR) and respiratory exchange ratio (RER) were measured, using indirect calorimetry, in 9 healthy, male subjects (28.6 +/- 3.3 years) under three conditions: (1) an inpatient, meal-controlled protocol (IPM) in which subjects were fed an evening meal and slept overnight in the laboratory prior to the morning test; (2) an outpatient, meal-controlled protocol (OPM) in which subjects were fed the same meal but slept at home prior to being transported to the laboratory for testing, and (3) and outpatient protocol (OP) in which meal was not controlled, but subjects were instructed to fast for 12 h prior to testing. There were no statistically significant differences in RMR between protocols (IPM = 7,928 +/- 360, OPM = 8,015 +/- 331 and OP = 7,987 +/- 315 kJ/day) or in fasting RER (IPM = 0.82 +/- 0.01, OPM = 0.82 +/- 0.02 and OP = 0.81 +/- 0.02). These data indicate that in young, healthy males RMR and RER are similar when measured under inpatient or outpatient conditions.