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The objective of this study was to determine if obstructive sleep apnea (OSA) subjects had elevated plasma homocysteine levels and a greater incidence of traditional cardiovascular risk factors. Case subjects (OSA group, n=24) without cardiovascular disease had an apnea-hypopnea index of 5 or higher; control subjects without cardiovascular disease served as a non-OSA group (n = 65). Demographic and anthropometric (ie, weight, height, body mass index [BMI], neck, waist, and hip circumferences) data were collected. Systolic and diastolic blood pressure (DBP) were measured. Fasting venous blood samples were collected to determine total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, creatinine, homocysteine, vitamin B 6 , vitamin B 12 , and folate status. In univariate analysis, BMI; neck, waist, and hip circumferences; serum total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and DBP were all positively associated with OSA. Plasma homocysteine concentration, however, had no effect on OSA. The age-adjusted odds ratio (OR) for all OSA and control subjects was significantly increased in the third tertile of homocysteine concentration (OR, 9.29; 95% CI, 1.25-69.12). However, the third tertile of plasma homocysteine showed no effect (OR, 3.24; 95% CI, 0.02-497.80) on OSA after additional adjustment for all cardiovascular risk factors. Homocysteine had no association with OSA; however, obesity, DBP, and serum total cholesterol are associated with OSA. Indices of central obesity (BMI and waist and neck circumferences) and a combination with DBP and serum total cholesterol level should be screened in patients with OSA.

A non-destructive method, called the Cure Referencing Method (CRM), was developed to measure the residual stresses in laminated composites. The method incorporates the use of moiré interferometry (a laser based optical method) and replication of diffraction gratings on the surface of laminates in the autoclave during cure. This allows the strains due to resin shrinkage and thermal expansion to be referenced back to the stress free state. For thermoset matrix composites, the stress free state exists just prior to matrix solidification. To determine the residual stress in multidirectional laminates, the strain difference from cure temperature to room temperature was first measured. Then, by doing the same for a unidirectional panel, that was cured simultaneously with the multidirectional laminate, the free thermal expansion of the unidirectional lamina could be defined for the multidirectional case. Using laminate theory, the residual stresses in each ply of the multidirectional laminate were calculated accordingly. The method was evaluated by measuring the residual stresses in balanced symmetric cross-ply, unbalanced symmetric cross-ply and symmetric angle-ply AS4/3501-6 graphite/epoxy laminates. To determine the repeatability of the method, five separate autoclave runs were performed, each with the three multidirectional panels, and the unidirectional panel.