Interaction between circadian rhythms and stress.

Life on earth has adapted to the day-night cycle by evolution of internal, so-called circadian clocks that adjust behavior and physiology to the recurring changes in environmental conditions. In mammals, a master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus receives environmental light information and synchronizes peripheral tissues and central non-SCN clocks to geophysical time. Regulatory systems such as the hypothalamus-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), both being important for the regulation of stress responses, receive strong circadian input. In this review, we summarize the interaction of circadian and stress systems and the resulting physiological and pathophysiological consequences. Finally, we critically discuss the relevance of rodent stress studies for humans, addressing complications of translational approaches and offering strategies to optimize animal studies from a chronobiological perspective.

Temperature dependent structured absorption spectra of molecular chlorine.

A dual wavelength range spectrometer system has been designed and constructed which can simultaneously perform single pass UV absorption spectroscopy and cavity enhanced absorption spectroscopy in the green region of the visible spectrum. Using the system the absorption spectrum of molecular chlorine has been measured, in the wavelength range 509-570 nm, using cavity enhanced absorption spectroscopy. Absolute absorption cross sections were obtained by simultaneous measurement of the UV spectrum to obtain the Cl(2) concentration. These are the first temperature dependent measurements of the Cl(2) absorption cross sections in this region which are vibronically resolved. Laboratory measurements were conducted at four temperatures (298, 273, 233, and 197 K). Spectral modelling of the Cl(2) B(3)Π(0(u)(+))-X(1)Σ(g)(+) electronic transition has been performed, the results of which are in good agreement with our measured spectra.

Denture use, malnutrition, frailty, and mortality among older women living in the community.

BACKGROUND: The relationships between denture use, malnutrition, frailty, and mortality in older women have not been well characterized. OBJECTIVE: To determine whether women who use dentures and have difficulty chewing or swallowing are at higher risk of malnutrition, frailty, and mortality. DESIGN: Cross-sectional and longitudinal study of 826 women, aged 70-79, from the Women's Health and Aging Studies, two population-based longitudinal studies of community-dwelling women in Baltimore, Maryland. At enrollment, data on frailty and self-reported denture use and difficulty chewing or swallowing that limited the ability to eat was collected, and plasma vitamins A, D, E, B6, and B12, carotenoids, folate, and albumin were measured. RESULTS: 63.5% of women reported using dentures, of whom 11.6% reported difficulty chewing or swallowing food. Denture users with and without difficulty chewing or swallowing and those not using dentures had, respectively, geometric mean (95% Confidence Interval [C.I.]) total plasma carotenoid concentrations of 1.481 (1.302, 1.684), 1.616 (1.535, 1.700), and 1.840 (1.728, 1.958) micromol/L, respectively (P < 0.0001), and 25- hydroxyvitamin D of 50.90 (44.25, 58.55), 47.46 (45.15, 50.40), and 54.0 (50.9, 56.8) nmol/L (P < 0.0001). The proportion using dentures among non-frail, pre-frail, and frail women was 58%, 66%, and 73%, respectively (P = 0.018). Women who used dentures and reported difficulty chewing or swallowing had lower five-year survival (H.R. 1.43, 95% C.I. 1.05-1.97), after adjusting for potential confounders. CONCLUSIONS: Older women living in the community who use dentures and have difficulty chewing or swallowing have a higher risk of malnutrition, frailty, and mortality.

Diabetes, hyperglycaemia and mortality in disabled older women: The Women's Health and Ageing Study I.

AIMS: Diabetes is associated with increased mortality in older adults, but the specific contributions of diabetes-associated clinical conditions and of increasing hyperglycaemia to mortality risk are unknown. We evaluated whether cardiovascular disease, comorbidities, or degree of hyperglycaemia, particularly severe hyperglycaemia, affected diabetes-related mortality risk in older, disabled women. METHODS: Six-year mortality follow-up of a random sample of 576 disabled women (aged 65-101 years), recruited from the Medicare eligibility list in Baltimore (MD, USA). All-cause and cardiovascular mortality were evaluated by diabetes status: no diabetes; diabetes with mild, moderate, and severe hyperglycaemia [defined by tertiles of glycosylated haemoglobin (GHB) among women with diabetes]. RESULTS: Diabetes with mild, moderate, and severe hyperglycaemia was associated with an increased hazard rate (HR) for all-cause mortality, even after adjustment for demographics, risks for cardiovascular disease, cardiovascular and non-cardiovascular conditions, and other known mortality risks. A dose-response effect was suggested [mild hyperglycaemia, HR 1.81, 95% confidence interval (CI) 1.03, 3.17; moderate hyperglycaemia, HR 2.02, 95% CI 1.34, 3.57; severe hyperglycaemia, HR 2.22, 95% CI 1.17, 4.25]. Women with diabetes had a significantly increased HR for non-cardiovascular death, but not for cardiovascular death, compared with those without diabetes. CONCLUSIONS: Diabetes, whether characterized by mild, moderate or severe hyperglycaemia, appears to be an independent risk factor for excess mortality in older disabled women and this risk may increase with increasing hyperglycaemia. This mortality risk is not completely explained by vascular complications, and involves non-cardiovascular deaths. Risks and benefits of diabetes management, including glycaemic control and management of vascular and other comorbidities, should be studied in older people with complications and comorbidities.

Guideline for the management of heart failure caused by systolic dysfunction: part II. Treatment.

Several large clinical trials conducted over the past decade have shown that pharmacologic interventions can dramatically reduce the morbidity and mortality associated with heart failure. These trials have modified and enhanced the therapeutic paradigm for heart failure and extended treatment goals beyond limiting congestive symptoms of volume overload. Part II of this two-part article presents treatment recommendations for patients with left ventricular systolic dysfunction. The authors recommend that, if tolerated and not contraindicated, the following agents be used in patients with left ventricular systolic dysfunction: an angiotensin-converting enzyme inhibitor in all patients; a beta blocker in all patients except those who have symptoms at rest; and spironolactone in patients who have symptoms at rest or who have had such symptoms within the past six months. Diuretics and digoxin should be reserved, as needed, for symptomatic management of heart failure. Other treatments or treatment programs may be necessary in individual patients.

Guideline for the management of heart failure caused by systolic dysfunction: Part I. Guideline development, etiology and diagnosis.

Over the past decade, the conceptual understanding of heart failure has changed significantly. Several large clinical trials have demonstrated that pharmacologic interventions can dramatically reduce the morbidity and mortality associated with heart failure. These trials have extended the therapeutic paradigm for treating heart failure beyond the goal of limiting congestive symptoms of volume overload. This two-part article presents an evidence-based guideline to assist primary care physicians in evaluating and treating patients with heart failure. Part I describes the new paradigm of heart failure and offers guidance for diagnostic testing. Part II presents a treatment guideline.

Explaining the role of sex on disability: a population-based study.

PURPOSE: There is no clear consensus about how sex influences prevalent disability and through what mechanisms. We investigated whether sex had a direct independent effect on disability or whether sex had an interactive effect on the relationship between chronic diseases/conditions and disability, and whether these effects differed in middle-aged versus older adults. DESIGN AND METHODS: We used baseline data from two nationally representative health interview surveys, the Health and Retirement Study (HRS) and the Study of Asset and Health Dynamics Among the Oldest Old (AHEAD), and disability and covariate measures that were nearly identical in both surveys. Logistic regression models tested the contributions of diseases, impairments, and demographic and social characteristics on difficulties with prevalent activities of daily living (ADLs), mobility, and strength. RESULTS: Models demonstrated no direct sex effect for ADL disability in either age group after adjusting for key covariates. However, sex did exert an indirect effect on ADL disability in older adults via musculoskeletal conditions and depressive symptoms. In contrast, female sex remained strongly associated with mobility and strength disability in both age groups, net of covariates. Major interactions were also significant, including a female sex/body mass index (BMI) interaction for mobility difficulty and several sex-disease interactions for strength disability in the middle-aged group. IMPLICATIONS: The effect of sex on ADL difficulty is largely explained by social and health-related covariates in middle-aged and older adults. In contrast, the independent association of female sex with decreased strength and mobility in both groups cannot be explained by our models' social or health-related variables. In addition, the positive association of BMI with mobility difficulty is significantly worse for women than for men.

Clinical characteristics and six-month outcomes of nursing home residents with low activities of daily living dependency.

BACKGROUND: Up to 30% of nursing home residents have very little dependency in activities of daily living (ADLs). We compared the characteristics and six-month outcomes of a sample of low-ADL--dependent nursing home residents (LDR) with other residents. METHODS: This is a cross-sectional, six-month follow-up study using secondary data analysis. We combined the separate 1990 and 1993 cohorts in the Resident Assessment Instrument evaluation study. In each case these data were collected in the same 254 nursing homes in 10 states. We studied residents with a length of stay greater than 60 days and age 65 years and older (N = 3955). We compared the baseline characteristics of LDR (n = 985) with all other residents. We then compared six-month outcomes of LDR with other residents and characteristics of LDR with poor outcomes (death or worsened ADL disability) with LDR who remained stable. RESULTS: The LDR had a significantly decreased frequency of geriatric syndromes (i.e., cognitive impairment, urinary incontinence, under-nutrition, vision problems, poor balance, and pressure ulcers) and neurological disease but had the same frequency of non-neurological chronic diseases and were on more medications. Thirty-one percent had poor six-month outcomes associated with baseline poor cognition, incontinence, poor appetite, and presence of vascular disease, daily pain, shortness of breath, and multiple medications. CONCLUSION: Our research identified 29% of nursing home residents with higher physical function (LDR) who had fewer geriatric syndromes and neurological disease diagnoses; 69% of these remained stable at 6 months. Those LDR with a higher risk of poor outcomes could be prospectively identified. LDR who remained stable for 6 months may represent a group who could potentially be maintained in the community.

Accelerated dysfunction among the very oldest-old in nursing homes.

BACKGROUND: The population aged 65 and older is often analyzed in three categories: young-old (65-74), middle-old (75-84), and oldest-old (> or = 85). This may blind heterogeneity within the oldest category. New, large data sets allow examination of the very oldest-old (e.g., aged > or = 95) and contrasts with those who are younger. METHODS: We determined the annual change of prevalence of physical and cognitive function, and of disease problems in the old to very oldest-old, using data from existing Resident Assessment Instrument records from nursing homes in seven states during 1992-1994. We used data from 193,467 unique residents aged 80 or older, including 6,556 residents aged 100 or older. We computed the prevalence, by age, of selected conditions: physical and cognitive function, diseases, problem behavior, mood disturbance, restraint use, falls, weight loss, eating less, body mass index, chewing and swallowing problems, incontinence (bowel and bladder), catheter use, and selected diagnoses. RESULTS: Prevalence of all measures of physical and cognitive dysfunction increased most rapidly with each year of age among the very oldest-old. Most of the slope changes occurred from 95 to 100 years of age. Such changes are less pronounced or not seen in measures of disease prevalence. CONCLUSIONS: Accelerated change in prevalence of dysfunction seen in the nursing home population may suggest a change in the mechanisms of aging that occur after the mid-nineties. Examination of the very oldest-old may provide new insight into the nature of the aging process.

Validity of the minimum data set for assessing nutritional status in nursing home residents.

The Minimum Data Set (MDS), a Health Care Financing Administration (HCFA)-mandated resident assessment system used in community nursing homes, is potentially useful for assessing nutritional status. We compared anthropometric measures of nutritional status available in the MDS [weight and body mass index (BMI)] with other anthropometric and bioelectrical measures of nutritional status, not available on the MDS. We also studied associations of MDS-measured clinical characteristics of nursing home residents with anthropometric and bioelectrical measures of lower and higher nutritional status, defined as measures in the 25th percentile and below, and 75th percentile and above, respectively. Data were from a sample of residents of an academic long-term care facility (n = 186, 75% female, mean age 89.9 +/- 5.6 y). Results were as follows: 1) MDS measures of weight and BMI were significantly correlated with all the anthropometric and bioelectrical measures of nutritional status in women, and most measures in men; 2) some MDS variables, including poor oral intake and advanced cognitive decline, were significantly associated with two or more anthropometric and bioelectrical measures of low nutritional status; and 3) complaints of hunger were significantly associated with two or more anthropometric and bioelectrical measures of high nutritional status. Results suggest that 1) weight and BMI, available in the MDS, are correlated with other measures of nutritional status not available, and 2) MDS clinical variables are associated with measures of low and high nutritional status, and may be useful in identifying patients at nutritional risk.

Characteristics related to poor glycemic control in NIDDM patients in community practice.

OBJECTIVE: To identify clinical characteristics related to poor glycemic control in patients with NIDDM cared for by Michigan primary care physicians. RESEARCH DESIGN AND METHODS: This study was a cross-sectional secondary analysis of data from 393 NIDDM patients (mean age, 63 +/- 11 years; 54% female; 92% white) in the 1990-1991 Michigan Diabetes in Communities II Study. We evaluated patient demographic, clinical, and physiological characteristics, attitudes toward diabetes, and self-care ability. Logistic regression was used for multivariate evaluation of the characteristics of those patients whose glycosylated hemoglobin (normal GHb 4-8%) was in the upper 25% of the study sample (GHb > 11.6%). RESULTS: A high meal-stimulated plasma C-peptide was associated with a lower likelihood of poor control (odds ratio [OR] for highest quartile vs. all others = 0.37; 95% CI 0.23-0.58). Longer time since diagnosis (OR for each 5 years duration = 1.28; 95% CI 1.07-1.53), poor self-care ability (OR = 1.85; 95% CI 1.27-2.71), and perceived absence of dietary recommendations (OR = 2.37; 95% CI 1.11-5.08) were also independently associated with presence in the highest GHb quartile. Characteristics that were not significantly related to poor glycemic control included sex, age, obesity, educational level, exercise, self-rated health status, and pharmacological treatment. CONCLUSIONS: 1) Poor glycemic control may reflect progressive failure of islet function, although the independent relationships of C-peptide level and time since diagnosis are consistent with concepts of heterogeneous mechanisms underlying NIDDM. 2) Despite the important relationships of biological characteristics of NIDDM to glycemic control, patient attitudes and self-care ability may be useful targets for designing management strategies for certain poorly controlled patients.

Factors associated with low body mass index and weight loss in nursing home residents.

BACKGROUND: Undernutrition in nursing home residents is a significant and possibly modifiable public health problem. We evaluated the hypothesis that some potentially modifiable factors are associated with resident undernutrition. METHODS: This study is a cross-sectional, secondary data analysis of 6,832 community nursing home residents sampled from 202 nursing homes in 7 states. Data were from the Minimum Data Set (MDS), and HCFA-mandated resident assessment instrument used in U.S. community nursing homes. Two dependent variables represented undernutrition: (a) low body mass index (BMI), defined as the lowest quartile BMI of the sample (19.42 kg/m2 and below); and (b) weight loss, an MDS measure defined as 5% decrease in weight in 30 days, or a 10% decrease in 180 days (9.9% of the sample). Independent variables included resident demographics, eating-related variables, variables measuring functional, cognitive, and affective statuses, and medical conditions. Separate logistic regression models were estimated for low BMI and weight loss to test multivariate associations. RESULTS: Poor oral intake, eating dependency, decubiti, and chewing problems increase the likelihood of both low BMI and weight loss. Female gender, age 85 or older, bedfast, and hip fracture increase the odds of low BMI only; depressed behaviors and two or more chronic diseases increase the odds of weight loss only. CONCLUSION: Undernutrition in nursing home residents is a multifactorial syndrome. Improved oral feeding methods and treatment of depression are potentially important ways to counteract undernutrition in nursing home residents by targeting reversible features.

The relationship of chronic diseases and health status to the health services utilization of older Americans.

OBJECTIVE: To study simultaneously the relationships among chronic diseases and physical health status as they affect health services utilization of older adults. DESIGN: Secondary analysis of a large, cross-sectional health interview survey, the Supplement on Aging of the 1984 National Health Interview Survey, using multiple equation methods to evaluate disease-specific impacts on physical health status, the direct impact of specific diseases on utilization of physician services and hospital care, and the indirect impact of specific diseases on utilization, mediated through physical health status. PARTICIPANTS: A total of 11,497 people aged 65 and older, representing a complex, multistage sample of the noninstitutionalized, older adult population of the United States. MEASUREMENTS: Predictor variables included specific chronic diseases (hypertension, arthritis, diabetes, cancer, and atherosclerotic heart disease), self-rated health status, and total number of disabilities. Control variables included age, gender, race, education, social integration. Outcome variables were physician visits and hospital stays. MAIN RESULTS: It was shown that different diseases have different relative impacts on physical health status, probability of utilization, and amount of utilization, if any, and different chronic diseases have a different mix of direct and indirect effects on utilization. CONCLUSION: The impact of chronic disease on health services utilization in a community-dwelling population is not a simple or direct relationship. Diseases vary according to their impact on different types of utilization, their impact on the probability of any health services use versus the amount of use, and on how much their effect on utilization is mediated through health status.