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Biomedical subjects

R Grunstein

Publications and source records attributed to R Grunstein.

16 recordsLinked to original sources
PubMed2006

Shift work and work injury in the New Zealand Blood Donors' Health Study.

OBJECTIVE: To investigate associations between work patterns and the occurrence of work injury. METHODS: A cross sectional analysis of the New Zealand Blood Donors Health Study conducted among the 15 687 (70%) participants who reported being in paid employment. After measurement of height and weight, a self-administered questionnaire collected information concerning occupation and work pattern, lifestyle behaviour, sleep, and the occurrence of an injury at work requiring treatment from a doctor during the past 12 months. RESULTS: Among paid employees providing information on work pattern, 3119 (21.2%) reported doing shift work (rotating with nights, rotating without nights, or permanent nights) and 1282 (8.7%) sustained a work injury. In unadjusted analysis, work injury was most strongly associated with employment in heavy manual occupations (3.6, 2.8 to 4.6) (relative risk, 95% CI), being male (1.9, 1.7 to 2.2), being obese (1.7, 1.5 to 2.0), working rotating shifts with nights (2.1, 1.7 to 2.5), and working more than three nights a week (1.9, 1.6 to 2.3). Snoring, apnoea or choking during sleep, sleep complaints, and excessive daytime sleepiness were also significantly associated with work injury. When mutually adjusting for all significant risk factors, rotating shift work, with or without nights, remained significantly associated with work injury (1.9, 1.5 to 2.4) and (1.8, 1.2 to 2.6), respectively. Working permanent night shifts was no longer significantly associated with work injury in the adjusted model. CONCLUSION: Work injury is highly associated with rotating shift work, even when accounting for increased exposure to high risk occupations, lifestyle factors, and excessive daytime sleepiness.

Accidents, Occupational↗
PubMed2000

Therapy with nCPAP: incomplete elimination of Sleep Related Breathing Disorder.

Correct assessment of the overall treatment effectiveness requires knowledge about therapy compliance and efficacy. This study aimed to determine overall long-term apnoea alleviation after continuous positive airway pressure (CPAP) in a complete sleep laboratory cohort. Out of 209 consecutive CPAP candidates (mean age 57+/-12 yrs, body mass index (BMI) 30.0+/-5.1 kg x m2, respiratory disturbance index (RDI) 32.9+/-29 h), follow-up treatment was performed in 149 of them at 9, 18 and 30 months after CPAP prescription. Compliance with CPAP (machine run time/days CPAP available) was adjusted for the individual subjective sleep-time. Apnoea alleviation was defined as adjusted compliance multiplied by the CPAP effect (RDI with CPAP applied), remaining RDI was calculated. The baseline RDI, age or BMI in 75 patients, who did not tolerate nasal continuous positive airway pressure (nCPAP), did not differ from those accepting CPAP (acceptors, n=74). In acceptors at 9 months follow-up RDI with CPAP applied was 1.4+/-2.6 (CPAP effect, n=66), mean CPAP use was 3.6+/-2.5 x 24 h(-1) (n=68), mean apnoea alleviation was 52.4+/-32.0% (range 1-100%, n=47), the average remaining whole-night RDI was 17.8+/-26. At 9, 18 and 30 months (n=47), the mean daily CPAP use increased from 3.6+/-2.5 h to 4.1+/-2.5 h and 4.4+/-2.4 h (p<0.01). Effectiveness of continuous positive airway pressure is potentially high but acceptance was low. When accounting for sleep-time, its actual effect and use, only 50% adjusted continuous positive airway pressure effectiveness was observed.

Adult↗
PubMed1997

Effects of ketone bodies on astrocyte amino acid metabolism.

The effects of acetoacetate and 3-hydroxybutyrate on glial amino acid metabolism were studied in primary cultures of astrocytes. The exchange of nitrogen among amino acids was measured with 15N as a metabolic probe and gas chromatography-mass spectrometry as a tool with which to quantify isotope abundance. Addition of either acetoacetate or 3-hydroxybutyrate (5 mM) to the incubation medium did not alter the initial rate of appearance of [15N]glutamate in the glia, but it did inhibit transamination of glutamate to [15N]aspartate. Addition of acetoacetate also inhibited formation of [2-(15)N]glutamine, but 3-hydroxybutyrate had a stimulatory effect. The presence in the medium of sodium acetate (5 mM) was also associated with diminished production of [15N]aspartate and [2-(15)N]glutamine with [15N]glutamate as precursor. Studies with [2-(15)N]glutamine as precursor indicated that treatment of the astrocytes with ketone bodies did not alter flux through the glutaminase pathway. Nor did the presence of the ketone bodies reduce significantly the flux of nitrogen from [15N]GABA to [2-(15)N]glutamine when the former species served as a metabolic tracer. The concentration of internal citrate increased in the presence of acetoacetate, 3-hydroxybutyrate, and acetate. Studies with purified sheep brain glutamine synthetase showed that citrate inhibited this enzyme. These findings are considered in terms of the known anticonvulsant effect of a ketogenic diet.

3-Hydroxybutyric Acid↗
PubMed1996

A double-blind, randomized trial of sabeluzole--a putative glutamate antagonist--in obstructive sleep apnea.

The effect of sabeluzole (SAB), an agent with anti-excitatory amino acid activity, on sleep, breathing and daytime symptoms was investigated in 13 patients with obstructive sleep apnea (OSA). There was marked interindividual variation in both the effect on sleep and breathing and the plasma concentration of SAB. However, individual plasma drug concentration was highly correlated (r = 0.82, p = 0.02) with a reduction of the oxygen desaturation index during sleep (ODI) after treatment with SAB. Further investigation of this and agents of this type are warranted in patients with OSA.

Adult↗
PubMed1996

Nasal continuous positive airway pressure treatment: current realities and future.

Nasal continuous positive airway pressure (CPAP) is a highly effective treatment for obstructive sleep apnea syndrome. The apnea/hypopnea index (AHI) is reduced 10-fold, but the patient dropout rate is up to 30%, and usage is typically < 5 hours per night. Titration, designed to make the best trade-off between effectiveness and side effects, is expensive. Autotitrating devices make this trade-off on a minute-by-minute basis, potentially reducing mean pressure delivery, reducing side effects, and increasing compliance. The aim of this study was to test the effectiveness of the AutoSet self-adjusting nasal CPAP system (ResMed, Sydney, Australia) in eliminating obstructive events and normalizing the arousal index. Forty-five subjects (41 males and 4 females with AHI) values of > 20/hour were recruited, with written informed consent. Subjects slept for a diagnostic night, followed by a treatment night, in the laboratory, using the AutoSet system with full polysomnographic monitoring of respiratory and sleep variables. Arousals were scored using ASDA criteria. Hypopneas were scored when there was a 50% reduction in ventilation for > 10 seconds, associated with a 4% drop in oxygen saturation. For comparison, the ASDA arousal index in 16 normal subjects (without nasal CPAP) is provided. Results are given as mean +/- standard error of the mean. AHI was reduced from 55 +/- 3 to 1.5 +/- 0.35 events/hour (p < 0.0001). The arousal index was reduced from 65 +/- 3 to 18 +/- 2 events/hour (p < 0.0001), identical to the value in the 16 healthy normal subjects. There was a 158% +/- 21% increase in slow-wave sleep (p = 0.01) and a 186% +/- 27% increase in rapid eye movement sleep (p = 0.013). The AutoSet self-adjusting nasal CPAP system adequately treats obstructive sleep apnea syndrome on the first night under laboratory conditions.

Female↗
PubMed1996

Energy expenditure in obstructive sleep apnea: effects of treatment with continuous positive airway pressure.

We examined 24-h energy expenditure (EE) in a chamber for indirect calorimetry in five male patients with obstructive sleep apnea (OSA) and six snoring control subjects (snorers). The 24-h EE was remeasured in patients with OSA after 3-mo treatment with nasal continuous positive airway pressure (CPAP). Patients with OSA had a greater degree of severe sleep-breathing disturbance than snorers. Patients with OSA had higher 24-h EE [39.2 +/- 3.0 vs. 33.9 +/- 2.7 kcal.24 h-1.kg fat-free mass (FFM)-1, P < 0.05], daytime urinary norepinephrine and vanillylmandelic acid (VMA), and aminoterminal procollagen III peptide (PIIIp) levels, and they tended to have higher sleeping EE (32.4 +/- 4.1 vs. 26.3 +/- 1.9 kcal.24 h-1.kg FFM-1, P < 0.1) than snorers. CPAP treatment normalized sleep architecture and breathing. CPAP treatment also decreased sleep EE (from 32.4 +/- 4.1 to 27.2 +/- 1.4 kcal.24 h-1.kg FFM-1, P < 0.05) and EE variability during sleep (from 1.6 +/- 0.5 to 1.0 +/- 0.5 kcal.24 h-1.kg FFM-1, P < 0.05) and increased the basal metabolic rate-to-sleep EE ratio in all subjects. Serum PIIIp and plasma norepinephrine decreased after CPAP in all patients. We conclude that OSA is associated with an increased sleep EE, which is normalized by treatment with CPAP.

Adult↗
PubMed1995

Obstructive sleep apnoea as a risk factor for hypertension.

It is controversial whether obstructive sleep apnoea (OSA) is a risk factor for hypertension as previous reviews of the subject have emphasized the confounding effect of obesity. We examined evidence from recent studies to reassess this debate. Cross-sectional studies from sleep clinic population (Sydney Sleep Cohort, Gothenburg Sleep Clinic Cohort), community sample (Busselton Sleep Survey, Wisconsin Sleep Cohort) and obese population (Swedish Obese Subjects Study) provide stronger evidence that the relationship between sleep apnoea and hypertension is an independent one. Moreover recent studies looking at the effect of sleep apnoea treatment have demonstrated a fall in blood pressure independent of weight change. More definitive studies are required but recent data provide increasing evidence that OSA is an independent risk factor for hypertension.

Journal Article↗
PubMed1995

Snoring and sleep apnea. A population study in Australian men.

Snoring and sleeping apnea are reportedly associated with morbidity. We used home monitoring (MESAM IV) to measure snoring and sleep apnea in 294 men aged 40 to 65 yr from the volunteer register of the Busselton (Australia) Health Survey. In this group, 81% snored for more than 10% of the night and 22% for more than half the night; 26% had a respiratory disturbance index (RDI) > or = 5, and 10% had an RDI > or = 10. There was a relatively low correlation between percentage of night spent snoring and RDI (rho = 0.47, p < 0.005). Subjective daytime sleepiness plus RDI > or = 5 occurred in a minimum of 3%. Obesity was related to snoring, RDI, and minimum SaO2 (all p < 0.0001). There was no relationship between age and either RDI or snoring, but increased age was related to minimum SaO2 < 85% (p < 0.05). Alcohol consumption was not related to sleep-disordered breathing. Smokers snored for a greater percentage of the night than nonsmokers (41 versus 31%, p = 0.01). We conclude that, in middle-aged men, both snoring and sleep apnea are extremely common, and in this age range both are associated with obesity but not with age. However, a high percentage of snoring is not essential for the occurrence of sleep apnea, nor does it necessarily indicate that apnea is present.

Adult↗
PubMed1994

Nitrazepam in patients with sleep apnoea: a double-blind placebo-controlled study.

We wanted to assess whether benzodiazepines worsen sleep apnoea, since their use in such patients has been controversial. Fourteen male patients with mild to moderate obstructive sleep apnoea were investigated in a placebo-controlled, double-blind study evaluating the influence of nitrazepam (NIT) on apnoea frequency and severity. Each patient was given oral nitrazepam 5 or 10 mg, or corresponding placebo, in a randomized order on three separate nights. Wash-out time was one week. A complete sleep study was undertaken at each study night. Eleven patients completed the study. Although there were individuals with marked variability in apnoea index between the three study nights, there was no significant change in apnoea index or minimum arterial oxygen saturation with any of the two nitrazepam dosages studied. Only 3 out of 11 patients had a higher apnoea index after both nitrazepam doses compared to placebo, and in these patients the increase in sleep-disordered breathing was of marginal clinical significance. Nitrazepam caused a modest increase in total sleep time and a decrease in rapid eye movement (REM) sleep. These results demonstrate that nitrazepam does not worsen sleep apnoea in patients with mild to moderate sleep apnoea. The previously reported sleep apnoea promoting effects of benzodiazepines may be restricted to a small subgroup of patients with sleep-disordered breathing.

Contraindications↗
PubMed1993

Snoring and sleep apnoea in men: association with central obesity and hypertension.

The objective of this study was to examine the relationship between sleep apnoea, measures of obesity and blood pressure. The study was cross-sectional in design, involving 1464 consecutive men undergoing sleep studies at two non-hospital sleep laboratories. Detailed sleep studies, body mass index (BMI), neck, hip and waist circumferences and morning and evening blood pressures were measured in each patient. Twenty-eight per cent of patients were obese (BMI > 30 kg/m2) and 47% were overweight (BMI 26-30 kg/m2). Body fat distribution in these patients was typically central with a mean waist-hip ratio (WHR) for the entire group of 0.99 with over 80% of patients having a WHR more than 0.94. Increasing severity of sleep apnoea measured either by respiratory disturbance index (RDI) or minimum oxygen saturation in sleep (MOS) was associated with increasing central obesity and morning but not evening blood pressure. Normal weight patients (BMI < 25 kg/m2) with sleep apnoea were characterized by increased waist and hip circumferences and increased morning diastolic blood pressure compared to patients without sleep apnoea. The best explanatory variables for sleep apnoea were waist (r2 = 0.156, P < 0.001) and age (r2 = 0.013, P = 0.003) only. Morning but not evening blood pressure was related to sleep apnoea independently of obesity and age. We concluded that patients with sleep apnoea are centrally obese. Waist circumference is a better predictor for sleep apnoea than neck circumference or BMI suggesting that the link between obesity and sleep apnoea cannot be explained solely by neck fat deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Kleine-Levin syndrome: a case report.

Kleine-Levin Syndrome is an unusual sleep disorder occurring predominantly, but not exclusively, in late adolescent males. A case is described which illustrates some of the difficulties in diagnosis and management.

Adolescent↗