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Biomedical subjects

Jamie C M Lam

Publications and source records attributed to Jamie C M Lam.

5 recordsLinked to original sources
PubMed2006

Randomised study of three non-surgical treatments in mild to moderate obstructive sleep apnoea.

BACKGROUND: Patients with mild to moderate obstructive sleep apnoea (OSA) may be managed with different treatment options. This study compared the effectiveness of three commonly used non-surgical treatment modalities. METHODS: Subjects with mild to moderate OSA were randomised to one of three treatment groups for 10 weeks: conservative measures (sleep hygiene) only, continuous positive airways pressure (CPAP) in addition to conservative measures or an oral appliance in addition to conservative measures. All overweight subjects were referred to a weight-reduction class. OSA was assessed by polysomnography. Blood pressure was recorded in the morning and evening in the sleep laboratory. Daytime sleepiness was assessed with the Epworth Sleepiness Scale. Health-related quality of life (HRQOL) was assessed with the 36-Item Short-Form Health Survey (SF-36) and Sleep Apnoea Quality of Life Index (SAQLI). RESULTS: 101 subjects with a mean (SEM) apnoea-hypopnoea index (AHI) of 21.4 (1.1) were randomised to one of the three groups. The severity of sleep-disordered breathing was decreased in the CPAP and oral appliance groups compared with the conservative measures group, and the CPAP group was significantly better than the oral appliance group. Relief from sleepiness was significantly better in the CPAP group. CPAP was also better than the oral appliance or conservative measures in improving the "bodily pain" domain, and better than conservative measures in improving the "physical function" domain of SF-36. Both CPAP and the oral appliance were more effective than conservative measures in improving the SAQLI, although no difference was detected between the CPAP and oral appliance groups. CPAP and the oral appliance significantly lowered the morning diastolic blood pressure compared with baseline values, but there was no difference in the changes in blood pressure between the groups. There was also a linear relationship between the changes in AHI and body weight. CONCLUSION: CPAP produced the best improvement in terms of physiological, symptomatic and HRQOL measures, while the oral appliance was slightly less effective. Weight loss, if achieved, resulted in an improvement in sleep parameters, but weight control alone was not uniformly effective.

Blood Pressure↗
PubMed2006

Advanced glycation endproducts in nondiabetic patients with obstructive sleep apnea.

SUBJECT OBJECTIVE: The formation and accumulation of advanced glycation endproducts (AGEs) has been implicated in the progression of age-related diseases such as diabetes mellitus and atherosclerosis. We hypothesize that AGE concentrations may be increased in subjects with obstructive sleep apnea (OSA), a condition associated with increased oxidative stress. METHODS: One hundred nineteen nondiabetic patients with OSA and 234 age-matched healthy controls and 134 patients with type 2 diabetes were recruited for participation in the study. Serum AGEs were assayed by competitive enzyme-linked immunosorbent assay using a polyclonal rabbit antisera raised against AGE-RNase. RESULTS: Serum AGEs were increased in OSA subjects, as compared with controls, but were less increased than the AGEs of patients with type 2 diabetes (control: 3.22 +/- 0.54 unit per mL; OSA: 3.68 +/- 0.39; diabetes mellitus: 4.11 +/- 0.99; analysis of variance p < .01). In the subjects with OSA, serum AGEs correlated with the duration of nocturnal desaturation (r = 0.21, p = .025) and plasma total 8-isoprostane concentration, a biochemical marker of oxidative stress (r = 0.22, p = .015), but not with fasting glucose level. On general linear model univariate analysis, the association between serum AGEs and 8-isoprostane was independent of age, sex, body mass index, smoking status, and glucose. CONCLUSION: Serum levels of AGEs were increased in nondiabetic subjects with OSA and were associated with the severity of OSA. Whether increased AGE formation contributes significantly to the high cardiovascular risk associated with OSA remains to be determined.

Diabetes Mellitus, Type 2↗
PubMed2005

Obstructive sleep apnea and the metabolic syndrome in community-based Chinese adults in Hong Kong.

OBJECTIVE: To investigate the relationship between obstructive sleep apnea (OSA) and the metabolic syndrome, an established cardiovascular risk factor, in middle-aged Chinese subjects. DESIGN: A prospective cross-sectional study from community-dwelling volunteers. SUBJECTS: Subjects of either sex between 30 and 60 years old were recruited from the staff in public institutions or visitors to community centers in Hong Kong. METHODS: Demographic and anthropomentric indices, blood pressure and metabolic profile (fasting blood glucose, total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol and triglycerides) were measured. Overnight polysomnographic studies were conducted. Presence of obstructive sleep apnea (OSA) was defined as apnea-hypopnea index (AHI)5. Metabolic syndrome was defined by the criteria of the National Cholesterol Education Panel, but using Asian cut-off values for abdominal obesity. RESULTS: A total of 255 subjects (150 men, 105 women) were studied. Subjects with OSA had five-fold risk of having metabolic syndrome. OSA was associated with the metabolic syndrome or its components, including waist circumference, diastolic blood pressure and fasting glucose, after adjusting for confounding variables. The independent determinants of OSA were age, gender, body mass index (BMI) and the metabolic syndrome. CONCLUSION: Among community-based middle-aged Chinese subjects, the metabolic syndrome was independent predictor of OSA.

Adult↗
PubMed2005

HDL dysfunction in obstructive sleep apnea.

OBJECTIVE: HDL is anti-atherogenic and has antioxidant property. HDL dysfunction has been reported in patients with coronary heart disease and we hypothesize that HDL may also be dysfunctional in obstructive sleep apnea (OSA), a condition associated with increased oxidative stress. METHODS: 128 OSA patients and 82 controls were recruited. HDL dysfunction was determined by evaluating the ability of HDL to inhibit LDL oxidation ex vivo. Plasma HDL was incubated with native LDL in the presence of dichlorofluorescein which fluoresced upon interaction with lipid oxidation products. Plasma levels of oxidized LDL and 8-isoprostane were measured by ELISA and a specific enzyme immunoassay, respectively. RESULTS: Plasma total 8-isoprostane levels were elevated in OSA subjects (p<0.01). Despite having similar concentrations of plasma lipids and apolipoproteins as controls, OSA subjects had greater degree of HDL dysfunction (p<0.01) and increased oxidized LDL levels (p<0.05). The apnea-hypopnea index was the main determinant of HDL dysfunction in OSA, accounting for 30% of its variance, with oxidized LDL and apolipoprotein AI contributing to 8% and 5% of its variance respectively (p<0.001). CONCLUSION: HDL is dysfunctional in preventing the formation and inactivation of oxidized lipids in OSA subjects and may partly contribute to their increased cardiovascular risk.

Adult↗