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Biomedical subjects

Robert Brunner

Publications and source records attributed to Robert Brunner.

9 recordsLinked to original sources
PubMed2006

Rigorous analysis of shadowing effects in blazed transmission gratings.

Blazed transmission gratings have become crucial components in many hybrid optical systems. Shadowing effects are known to occur at their passive blaze facets, which may impair the system's efficiency performance. For optical designs, it is desirable to have a simple but accurate description of this phenomenon. We show that the efficiency reduction in low diffraction orders is dominated by a linear dependence on the ratio of wavelength to grating period rather than a quadratic dependence as proposed in extended scalar theory. The strength of the electromagnetic shadowing will be determined using rigorous diffraction methods and discussed with respect to imaging optical components. Results are compared to existing ray-optical models.

Journal Article↗
PubMed2006

Panic attacks, daily life ischemia, and chest pain in postmenopausal women.

BACKGROUND: Chest pain is a common symptom of panic attacks, but little is known about the relationship in older women among panic attacks, chest pain, and daily life ischemia. METHODS: The authors conducted a cross-sectional survey of 3063 community-dwelling, generally healthy postmenopausal women enrolled between 1997 and 2000 in the Myocardial Ischemia and Migraine Study in 10 clinical centers of the 40-center Women's Health Initiative. Participants, ages 50 to 79 years, completed a questionnaire about occurrence of panic attacks in the previous 6 months and underwent 24-hour ambulatory electrocardiogram monitoring (AECG); 2705 women had valid AECG recordings and panic attack questionnaires. ST depression on AECG, heart rate variability (HRV), and chest pain episodes were compared among women with and without a 6-month history of panic attack. RESULTS: There was no difference in overall prevalence of ischemic episodes during AECG between women with and without panic attacks. Women with a recent history of panic were more likely to experience chest pain during AECG after controlling for potential confounders (odds ratio [OR] = 2.01; 95% confidence interval [CI] = 1.40-2.88), including both nonischemic (OR = 1.83; 95% CI = 1.26-2.65) and ischemic chest pain (OR = 4.94; 95% CI = 1.41-17.30). Although mean HRV was lower in those with panic attacks (p = .017), this was not significant after controlling for confounders. CONCLUSIONS: Postmenopausal women with a recent history of panic attacks do not appear to have more daily life ischemia as measured by occurrence of ST depression during 24-hour monitoring, but do have more chest pain and possibly lower HRV, suggesting that even sporadic panic attacks may be related to cardiovascular risk.

Activities of Daily Living↗
PubMed2006

Effects of combination estrogen plus progestin hormone treatment on cognition and affect.

CONTEXT: Some studies of hormone treatment in postmenopausal women suggest benefits on specific cognitive functions, particularly memory. OBJECTIVE: The objective of this study was to determine whether hormone therapy influences changes in specific cognitive functions and affect in older women. DESIGN: This study was a randomized, double-blind, placebo-controlled clinical trial. SETTING: Participants were women from 14 of 40 clinical centers of the Women's Health Initiative (WHI). PARTICIPANTS: Postmenopausal women (1416) aged 65 yr and older, free of probable dementia, and enrolled in WHI and the WHI Memory Study (WHIMS) trial of combination estrogen and progestin for a mean of 3 yr and followed for a mean of 1.35 yr, were studied. INTERVENTION: Intervention was conjugated equine estrogen (CEE; 0.625 mg) with 2.5 mg medroxyprogesterone acetate (MPA) in one daily tablet (CEE + MPA) or placebo. MAIN OUTCOME MEASURES: Annual rates of change in specific cognitive functions and affect, adjusted for time since randomization, were measured. RESULTS: CEE + MPA had a negative impact on verbal memory (P <or= 0.01) and a trend to a positive impact on figural memory (P = 0.012) over time compared with placebo, but other cognitive domains were not affected. Both effects on memory were evident only after long-term therapy. CEE + MPA did not significantly influence positive affect, negative affect, or depressive symptoms. CONCLUSIONS: The effect of CEE + MPA on cognitive function varies across cognitive domains in older women, reflecting both possible beneficial and detrimental actions of ovarian steroids on the aging brain. Our results extend prior findings about dementia and global cognitive function to age-related changes in specific cognitive functions and suggest directions for future research.

Affect↗
PubMed2004

Conjugated equine estrogens and global cognitive function in postmenopausal women: Women's Health Initiative Memory Study.

CONTEXT: The Women's Health Initiative Memory Study (WHIMS) previously reported that estrogen plus progestin therapy does not protect cognition among women aged 65 years or older. The effect of estrogen-alone therapy, also evaluated in WHIMS, on cognition has not been established for this population. OBJECTIVES: To determine whether conjugated equine estrogen (CEE) alters global cognitive function in older women and to compare its effect with CEE plus medroxyprogesterone acetate (CEE plus MPA). DESIGN, SETTING, AND PARTICIPANTS: A randomized, double-blind, placebo-controlled ancillary study of the Women's Health Initiative (WHI), WHIMS evaluated the effect of CEE on incidence of probable dementia among community-dwelling women aged 65 to 79 years with prior hysterectomy from 39 US academic centers that started in June 1995. Of 3200 eligible women free of probable dementia enrolled in the WHI, 2947 (92.1%) were enrolled in WHIMS. Analyses were conducted on the 2808 women (95.3%) with a baseline and at least 1 follow-up measure of global cognitive function before the trial's termination on February 29, 2004. INTERVENTIONS: Participants received 1 daily tablet containing either 0.625 mg of CEE (n = 1387) or matching placebo (n = 1421). MAIN OUTCOME MEASURE: Global cognitive function measured annually with the Modified Mini-Mental State Examination (3MSE). RESULTS: During a mean follow-up of 5.4 years, mean (SE) 3MSE scores were 0.26 (0.13) units lower than among women assigned to CEE compared with placebo (P =.04). For pooled hormone therapy (CEE combined with CEE plus MPA), the mean (SE) decrease was 0.21 (0.08; P =.006). Removing women with dementia, mild cognitive impairment, or stroke from the analyses lessened these differences. The adverse effect of hormone therapy was more pronounced among women with lower cognitive function at baseline (all P<.01). For women assigned to CEE compared with placebo, the relative risk of having a 10-unit decrease in 3MSE scores (>2 SDs) was estimated to be 1.47 (95% confidence interval, 1.04-2.07). CONCLUSION: For women aged 65 years or older, hormone therapy had an adverse effect on cognition, which was greater among women with lower cognitive function at initiation of treatment.

Aged↗
PubMed2004

Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: the Women's Health Initiative randomized controlled trial.

CONTEXT: Despite decades of use and considerable research, the role of estrogen alone in preventing chronic diseases in postmenopausal women remains uncertain. OBJECTIVE: To assess the effects on major disease incidence rates of the most commonly used postmenopausal hormone therapy in the United States. DESIGN, SETTING, AND PARTICIPANTS: A randomized, double-blind, placebo-controlled disease prevention trial (the estrogen-alone component of the Women's Health Initiative [WHI]) conducted in 40 US clinical centers beginning in 1993. Enrolled were 10 739 postmenopausal women, aged 50-79 years, with prior hysterectomy, including 23% of minority race/ethnicity. INTERVENTION: Women were randomly assigned to receive either 0.625 mg/d of conjugated equine estrogen (CEE) or placebo. MAIN OUTCOME MEASURES: The primary outcome was coronary heart disease (CHD) incidence (nonfatal myocardial infarction or CHD death). Invasive breast cancer incidence was the primary safety outcome. A global index of risks and benefits, including these primary outcomes plus stroke, pulmonary embolism (PE), colorectal cancer, hip fracture, and deaths from other causes, was used for summarizing overall effects. RESULTS: In February 2004, after reviewing data through November 30, 2003, the National Institutes of Health (NIH) decided to end the intervention phase of the trial early. Estimated hazard ratios (HRs) (95% confidence intervals [CIs]) for CEE vs placebo for the major clinical outcomes available through February 29, 2004 (average follow-up 6.8 years), were: CHD, 0.91 (0.75-1.12) with 376 cases; breast cancer, 0.77 (0.59-1.01) with 218 cases; stroke, 1.39 (1.10-1.77) with 276 cases; PE, 1.34 (0.87-2.06) with 85 cases; colorectal cancer, 1.08 (0.75-1.55) with 119 cases; and hip fracture, 0.61 (0.41-0.91) with 102 cases. Corresponding results for composite outcomes were: total cardiovascular disease, 1.12 (1.01-1.24); total cancer, 0.93 (0.81-1.07); total fractures, 0.70 (0.63-0.79); total mortality, 1.04 (0.88-1.22), and the global index, 1.01 (0.91-1.12). For the outcomes significantly affected by CEE, there was an absolute excess risk of 12 additional strokes per 10 000 person-years and an absolute risk reduction of 6 fewer hip fractures per 10 000 person-years. The estimated excess risk for all monitored events in the global index was a nonsignificant 2 events per 10 000 person-years. CONCLUSIONS: The use of CEE increases the risk of stroke, decreases the risk of hip fracture, and does not affect CHD incidence in postmenopausal women with prior hysterectomy over an average of 6.8 years. A possible reduction in breast cancer risk requires further investigation. The burden of incident disease events was equivalent in the CEE and placebo groups, indicating no overall benefit. Thus, CEE should not be recommended for chronic disease prevention in postmenopausal women.

Aged↗
PubMed2004

Diffraction-based solid immersion lens.

A solid immersion lens based on diffraction (dSIL) is proposed as an alternative to the conventional design based on refraction. A design analogous to a Fresnel zone plate is derived in accordance with the Huygens-Fresnel principle. Fabrication of a binary dSIL is achieved by electron-beam lithography and reactive-ion etching on LaSF35, with index n = 2.014. Measurement of the point-spread function is performed with near-field optical microscopy. The results are in accord with the expected resolution enhancement of a factor n with respect to the diffraction limit.

Journal Article↗
PubMed2002

Vigorous leisure activity through women's adult life: the Women's Health Initiative Observational Cohort Study.

This study described differences in vigorous activity participation recalled across the life span, assessed whether reports of past vigorous activity were associated with current participation, and examined factors associated with participation in current vigorous activity among women. After the exclusion of women aged 50-54 years, the study population included 71,837 multiethnic postmenopausal women aged 55-79 years who were participating in the Women's Health Initiative Observational Cohort Study, 1993-1998. Vigorous activity was assessed retrospectively for ages 18, 35, and 50 years and currently at enrollment into the study (median age, 65 years). Current participation in vigorous activity (>3 days/week) was low and consistent across racial/ethnic groups (13-16%). The prevalence of vigorous activity declined with age, with the largest decrease in vigorous activity occurring after age 50 years for all racial/ethnic groups. Current vigorous activity was generally higher among women with a lower body mass index, not currently smoking, in excellent general health, and of higher socioeconomic status across racial/ethnic groups. These data suggest that a lower prevalence of vigorous activity in the postmenopausal period is part of a complex of health-related attitudes and behaviors that transcends race/ethnicity. The perimenopausal period may be a critical juncture at which targeted and tailored interventions may help to achieve maintenance of physical activity into the postmenopausal period.

Adolescent↗