A double-spike MC TIMS measurement procedure for low-amount Ca isotopic analysis of limited biological tissue samples.

The application of Ca isotopic analysis in biomedical studies has great potential to identify changes in Ca metabolism and bone metabolism. Reliable measurement of Ca isotope-amount ratios is challenging considering limited Ca amounts and significant procedural blank levels. In this study, Ca purification was performed using the DGA Resin, optimized for low procedural blanks and separation of Ca from matrix elements and isobaric interferences (Na, Mg, K, Ti, Fe, Ba), while maintaining quasi-quantitative recoveries which are sufficient since a 42Ca-48Ca double-spike (DS) was applied. Ca isotopic analysis was performed using multicollector thermal ionization mass spectrometry (MC TIMS). The obtained procedural Ca blank of ≤10 ng enables processing of limited Ca amounts down to 670 ng. Data reduction of the measured Ca isotope-amount ratios was performed using an in-house developed software solving the DS algorithm. Data quality was improved by extension of equilibration time of the sample-DS mixture and implementation of a normalization strategy for raw isotopic data. The reported δ(44Ca/40Ca)NIST SRM 915a of NIST SRM 915a processed as a sample was found to be 0.01 ‰ ± 0.08 ‰ (2 SD, n = 15). Ca isotope-amount ratios of the reference material NIST SRM 1400 (bone ash), NIST SRM 1486 (bone meal), GBW07601 (human hair), and IAPSO (seawater) were in good agreement within uncertainty with literature data. Novel data on additional reference materials for biological tissues (hair) is presented, which might indicate a potential fractionation of Ca incorporated into hair tissue when compared to the blood pool.

A fully automated simultaneous single-stage separation of Sr, Pb, and Nd using DGA Resin for the isotopic analysis of marine sediments.

A novel, fast and reliable sample preparation procedure for the simultaneous separation of Sr, Pb, and Nd has been developed for subsequent isotope ratio analysis of sediment digests. The method applying a fully automated, low-pressure chromatographic system separates all three analytes in a single-stage extraction step using self-packed columns filled with DGA Resin. The fully automated set-up allows the unattended processing of three isotopic systems from one sediment digest every 2 h, offering high sample throughput of up to 12 samples per day and reducing substantially laboratory manpower as compared to conventional manual methods. The developed separation method was validated using the marine sediment GBW-07313 as matrix-matched certified reference material and combines quantitative recoveries (>90% for Sr, >93% for Pb, and >91% for Nd) with low procedural blank levels following the sample separation (0.07 µg L-1 Sr, 0.03 µg L-1 Pb, and 0.57 µg L-1 Nd). The average δ values for Sr, Pb, and Nd of the separated reference standards were within the certified ranges (δ (87Sr/86Sr)NIST SRM 987 of -0.05(28) ‰, δ(208Pb/206Pb)NIST SRM 981 of -0.21(14) ‰, and δ(143Nd/144Nd)JNdi-1 of 0.00(7) ‰). The DGA Resin proved to be reusable for the separation of >10 sediment digests with no significant carry-over or memory effects, as well as no significant on-column fractionation of Sr, Pb, and Nd isotope ratios. Additional spike experiments of NIST SRM 987 with Pb, NIST SRM 981 with Sr, and JNdi-1 with Ce revealed no significant impact on the measured isotopic ratios, caused by potential small analyte peak overlaps during the separation of Sr and Pb, as well as Ce and Nd.

Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS.

Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector-inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'point-by-point', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'point-by-point' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP-7 test samples.

Preventive healthcare use among males with multiple sclerosis.

OBJECTIVES: To understand preventive healthcare use by males with multiple sclerosis (MS). STUDY DESIGN: Cross-sectional survey with secondary comparative data. METHODS: Primary survey data were collected from male veterans with MS (n = 1142) and compared with national surveillance data for a general veteran population (n = 31,500) and a general population (n = 68,357). Analyses compared use by group and identified variables associated with service use by male veterans with MS. RESULTS: More veterans with MS had a cholesterol check (93%) than the general veteran population (89%, P < 0.001) and the general population (78%, P < 0.001). More veterans with MS had received annual influenza vaccination (69%) than the general veteran population (58%, P < 0.001) and the general population (42%, P < 0.001). More veterans with MS (81%) had ever received pneumonia vaccination than the general veteran population (67%) and the general population (51%) (P < 0.001). Colon screening was received by 55% of veterans with MS, 49% of the general veteran population (P < 0.001), and 39% of the general population (P < 0.0001). Fewer veterans with MS (34%) had received a prostate-specific antigen (PSA) test and digital rectal examination than the general veteran population (46%, P < 0.001) and the general population (36%, not significant). In males with MS, variables independently associated with cholesterol checks were: white race [odds ratio (OR) = 3.75] and living in the south (OR = 1.95); variables independently associated with influenza vaccination were increased age (OR = 1.03) and being a non-smoker (OR = 0.55); increased age was independently associated with colon screening (OR = 1.02); variables independently associated with PSA testing were increased age (OR = 1.08) and being employed (OR = 3.31), and being unemployed was independently associated with pneumonia vaccination (OR = 0.16). CONCLUSIONS: More males with MS received several recommended preventive health services (e.g. cholesterol and colon screening, influenza and pneumonia vaccination) than males without MS. The Veterans Health Administration is meeting many prevention needs in males with MS, but there is room for improvement in areas such as reducing disparities in PSA screening and increasing respiratory vaccinations to meet national targets.

Identification of Marchfeld asparagus using Sr isotope ratio measurements by MC-ICP-MS.

This work focuses on testing and application of Sr isotope signatures for the fast and reliable authentication and traceability of Asparagus officinalis originating from Marchfeld, Austria, using multicollector inductively coupled plasma mass spectrometry after optimised Rb/Sr separation. The major sample pool comprises freeze-dried and microwave-digested asparagus samples from Hungary and Slovakia which are compared with Austrian asparagus originating from the Marchfeld region, which is a protected geographical indication. Additional samples from Peru, The Netherlands and Germany were limited in number and allowed therefore only restricted statistical evaluation. Asparagus samples from Marchfeld were harvested within two subsequent years in order to investigate the annual variation. The results show that the Sr isotope ratio is consistent within these 2 years of investigation. Moreover, the Sr isotope ratio of total Sr in soil was found to be significantly higher than in an NH4NO3 extract, reflecting the mobile (bioavailable) phase. The isotope composition in the latter extract corresponds well to the range found in the asparagus samples in Marchfeld, even though the concentration of Sr in asparagus shows no direct correlation to the concentration of Sr in the mobile phase of the soil. The major question was whether the 'Marchfelder Spargel' can be distinguished from samples from the neighbouring countries of Hungary and Slovakia. According to our findings, they can be clearly (100%) singled out from the Hungarian samples and can be distinguished from the Slovakian asparagus samples with a probability of more than 80%.

Determination of (90)Sr in soil samples using inductively coupled plasma mass spectrometry equipped with dynamic reaction cell (ICP-DRC-MS).

A rapid method is reported for the determination of (90)Sr in contaminated soil samples in the vicinity of the Chernobyl Nuclear Power Plant by ICP-DRC-MS. Sample preparation and measurement procedures focus on overcoming the isobaric interference of (90)Zr, which is present in soils at concentrations higher by more than six orders of magnitude than (90)Sr. Zirconium was separated from strontium in two steps to reduce the interference by (90)Zr(+) ions by a factor of more than 10(7): (i) by ion exchange using a Sr-specific resin and (ii) by reaction with oxygen as reaction gas in a dynamic reaction cell (DRC) of a quadrupole ICP-MS. The relative abundance sensitivity of the ICP-MS was studied systematically and the peak tailing originating from (88)Sr on mass 90 u was found to be about 3 x 10(-9). Detection limits of 4 fg g(-1) (0.02 Bq g(-1)) were achieved when measuring Sr solutions containing no Zr. In digested uncontaminated soil samples after matrix separation as well as in a solution of 5 microg g(-1) Sr and 50 ng g(-1) Zr a detection limit of 0.2 pg g(-1) soil (1 Bq g(-1) soil) was determined. (90)Sr concentrations in three soil samples collected in the vicinity of the Chernobyl Nuclear Power Plant were 4.66+/-0.27, 13.48+/-0.68 and 12.9+/-1.5 pg g(-1) corresponding to specific activities of 23.7+/-1.3, 68.6+/-3.5 and 65.6+/-7.8 Bq g(-1), respectively. The ICP-DRC-MS results were compared to the activities measured earlier by radiometry. Although the ICP-DRC-MS is inferior to commonly used radiometric methods with respect to the achievable minimum detectable activity it represents a time- and cost-effective alternative technique for fast monitoring of high-level (90)Sr contamination in environmental or nuclear industrial samples down to activities of about 1 Bq g(-1).

Adherence to immunosuppression: a prospective diary study.

Immunosuppression adherence among kidney transplant recipients is essential for graft survival. However, nonadherence is common, jeopardizing graft survival. Besides skipping dosages, little is known about other forms of medication nonadherence and their underlying reasons. This study sought to examine patients' extent of medication adherence over time and reasons for nonadherence. Thirty-nine new kidney transplant recipients were asked to complete a month-long medication-taking diary that included reporting medication nonadherence such as skipped medications, medications taken early or late, taking dosages greater or less than prescribed, and the reason for each occurrence of nonadherence. Of the 20 (51%) patients who completed the diary, 11 (55%) reported at least 1 form of nonadherence. Eleven patients reported taking their immunosuppression at least 1 hour later than the prescribed time, 1 patient reported skipping medication, but no patients reported changing the dosage on their own. Immunosuppression was taken on average 1.5 hours after the prescribed time. Of those patients who took their medications late, there were on average 3.1 occasions of taking it late. The most common reasons for this behavior included health care-related issues, followed by oversleeping, being away from home, work-related barriers, and forgetting. The majority of kidney transplant recipients took medications later than prescribed during 1 month. Future research should determine the clinical impact on graft function of late administration of immunosuppression. Interventions should be designed to better assist kidney recipients with taking medications on time, especially when they are away from home.

Long-term in vivo degradation behavior and near-implant distribution of resorbed elements for magnesium alloys WZ21 and ZX50.

UNLABELLED: We report on the long-term effects of degrading magnesium implants on bone tissue in a growing rat skeleton using continuous in vivo micro-Computed Tomography, histological staining and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Two different magnesium alloys-one rapidly degrading (ZX50) and one slowly degrading (WZ21)-were used to evaluate the bone response and distribution of released Mg and Y ions in the femur of male Sprague-Dawley rats. Regardless of whether the alloy degrades rapidly or slowly, we found that bone recovers restitutio ad integrum after complete degradation of the magnesium implant. The degradation of the Mg alloys generates a significant increase in Mg concentration in the cortical bone near the remaining implant parts, but the Mg accumulation disappears after the implant degrades completely. The degradation of the Y-containing alloy WZ21 leads to Y enrichment in adjacent bone tissues and in newly formed bone inside the medullary space. Locally high Y concentrations suggest migration not only of Y ions but also of Y-containing intermetallic particles. However, after the full degradation of the implant the Y-enrichment disappears almost completely. Hydrogen gas formation and ion release during implant degradation did not harm bone regeneration in our samples. STATEMENT OF SIGNIFICANCE: Magnesium is generally considered to be one of the most attractive base materials for biodegradable implants, and many magnesium alloys have been optimized to adjust implant degradation. Delayed degradation, however, generates prolonged presence in the organism with the risk of foreign body reactions. While most studies so far have only ranged from several weeks up to 12months, the present study provides data for complete implant degradation and bone regeneration until 24months, for two magnesium alloys (ZX50, WZ21) with different degradation characteristics. µCT monitoring, histological staining and LA-ICP-MS illustrate the distribution of the elements in the neighboring bony tissues during implant degradation, and reveal in particular high concentrations of the rare-earth element Yttrium.

Age, symptom interpretation, and health behavior.

The role of symptom perceptions and utilization of health promoting practices in illness behavior were explored across the adult lifespan. The first study (N = 396) assessed the health practices and perceptions about illnesses in well adults (ages 20 to 89) as well as perceptions about symptoms associated with a group of six specific illnesses. The second community study (N = 614) examined how symptom qualities (symptom severity, duration, and illness label) affect attributions of symptoms to aging and coping strategies in response to the symptoms. The findings revealed that while the elderly report more frequent performance of health promoting activities, perceptions about illnesses and how to prevent them are comparable across adulthood. Symptoms used to identify illnesses are also equivalent across adulthood (and aging) except for the reduced usage of mild ambiguous symptoms in identifying illnesses by the elderly. The frequency with which mild, short-term symptoms are attributed to aging increases with age of the subjects and leads to greater acceptance of the illness symptoms and more passive coping strategies. Clinical implications and policy recommendations are discussed.

Nursing home admission for African Americans with Alzheimer's disease.

BACKGROUND: For African Americans with Alzheimer's disease (AD), little is known about the time to, and risk factors for, nursing home admission (NHA). Using Consortium To Establish a Registry for Alzheimer's Disease (CERAD) data, this study provides information on NHA for African Americans. METHODS: This longitudinal study followed subjects (N=122) for as long as 7 years and used survival analysis methodology and variable values at baseline and at follow-up to identify NHA risk factors. Studied were sociodemographic variables, physical symptom and disease status variables, the Blessed Dementia Rating Scale (including subscores), the Clinical Dementia Rating (CDR), and the Mini-Mental State Examination. RESULTS: Only 25% of African Americans with AD were estimated to have had a NHA by 3.4 years (confidence interval 2.1, 5.4). Being unmarried resulted in a five times earlier NHA (p< .01), and each unit increase in the CDR resulted in a 74% earlier NHA (p<.01). In the absence of the CDR, limitation in activities of daily living was associated with earlier NHA (p<.05). CONCLUSIONS: Findings suggest that African Americans with AD spend a substantial time in the community prior to NHA, a longer time than observed in similar studies among whites. This raises public health and clinical concern that African Americans with AD may be residing in the community with substantial unmet needs, and that their caregivers have potentially high levels of burden. The independent associations with time to NHA observed here, although few in number, are consistent with other related research.

A survey of exercise beliefs and exercise habits among people with arthritis.

OBJECTIVE: To explore a possible explanation for the problem of why few people exercise despite the positive health advantages, by examining the relationship between exercise beliefs and participation in exercise activities. METHODS: Eighty-one respondents aged 27-80 were recruited from 3 Chicago-area health care facilities to complete the study survey; 68 (84%) did so. Participants were asked about their participation in 6 types of exercise activities; they also reported their beliefs concerning their ability to exercise (self-efficacy for exercise), barriers to exercise, benefits of exercise, and the impact of exercise on their arthritis. RESULTS: Study results indicate that belief in the benefits of exercise and self-efficacy for exercise are associated with participation in exercise activities. Also, severity of disease differentiated exercisers from non-exercisers. CONCLUSIONS: Results suggest the importance of finding ways to strengthen belief in the benefits of exercise and self-efficacy for exercise in people with arthritis, particularly people with moderate to severe disease-related limitations.

Impact of symptoms and aging attribution on emotions and coping.

Two experimental studies and a large field study were designed to examine how symptom severity, symptom duration, symptom ambiguity, and the association of symptoms with aging affected emotional responses and coping with illness threats. In Study 1, 280 respondents from the surrounding community reported the emotional and coping responses they would manifest to scenarios that varied the severity, duration, and ambiguity (i.e., labeled vs. unlabeled) of a common set of symptoms. Severity had more of an impact on coping strategies than did duration or illness label; severe symptoms elicited stronger emotional upset and a higher incidence of both self-care behaviors and seeking of medical care. Symptoms of longer duration also resulted in increased seeking of medical care. Responses of the 334 adults participating in Study 2 replicated and extended these findings: A closed-ended item asking participants whether the symptoms could be attributed to aging showed that attribution of symptoms to aging increased with age, was more frequent for mild symptoms, and was associated with reduced emotional response to symptoms and a tendency to delay seeking treatment. Participants in the field study (168 patients seeking medical care for a variety of symptoms) completed interviews tracing symptom processing and emotional and coping reactions. The results provided evidence for the external validity of the scenario studies, as the attribution of symptoms to aging was greater for older than younger patients and resulted in a significant tendency to delay seeking medical care. Results of these studies suggest that symptom experience and symptom interpretation must be considered in the study of coping responses to illness threats.

Who hasn't heard about AIDS?

This article analyzes who among the general population has not heard about AIDS despite intensive educational programs and widespread media attention about the syndrome. The data are drawn from a survey of the general public's knowledge, attitudes, and behavior toward AIDS in May-July, 1987 to establish a baseline for future educational interventions and to identify groups in need of special educational efforts. A total of 1540 interviews were conducted in Chicago and the surrounding six-county metropolitan area with adults between the ages of 18 and 60 in a two-stage cluster sample designed to compare blacks, whites, and Hispanics. Of the 1540 respondents, 49 (3.2%) had never heard of AIDS. Contingency table and logistic regression analyses indicated that lower educational levels and being Hispanic or Asian predict not having heard about AIDS. The results suggest the need for programs and intervention strategies that consider the special characteristics of these populations.

Sources of attrition in a church-based exercise program for older African-Americans.

Among 123 older African Americans recruited into a church-based exercise program, 43% had dropped out within four months. Compared to those who did not drop out, drop outs had lower levels of education, energy to do activities, energy to exercise, and self-ratings of health, all based on measures taken before the class. Over half of those who dropped out cited non-exercise related health problems, and 17% caregiver responsibilities. Of those who dropped out, half said they would continue to exercise and 32% said they intended to start within the next six months.

Use of medical care by African American and White older persons: comparative analysis of three national data sets.

Historically, there has been a large gap between African Americans and Whites in access to health care, but this gap was ostensibly lessened by the advent of Medicare and Medicaid for older adults in the mid 1960s. The extent to which older African Americans continue to receive less access to medical care as a result of economic inequalities, institutionalized forms of discrimination, and life-style factors remains a subject of policy debate. Empirical enquiry has produced inconsistent results. The purpose of this study is to test the same set of models of medical use using identically measured predictor variables in three nationally representative data sets of older Americans: 1984 Study of Aging (SOA); 1984 National Long-Term Care Survey (NLTC); and the 1987 National Medical Care Expenditure Survey (NMES). Multivariate logistic regression of use of physician and hospital services and Poisson regression of amount of service use identified inconsistent results in race differences across data sets, but consistent results in terms of the importance of health status and insurance as predictors of use and amount of use. The findings suggest that health status and financial resources may be more relevant areas for policy interventions than considerations related to race and ethnicity.

Minority use of community long-term care services: a comparative analysis.

A series of national surveys since 1982 have examined health needs of elders. Small proportions of minority elders in each sample have limited our understanding of service use by minorities. This research sought to determine (1) the extent to which minorities have restricted use of community long-term care services as a result of socioeconomic status, family structure, and health status, and (2) the replicability and validity of results across three national surveys: Supplement on Aging, National Long-Term Care, and National Medical Expenditure. Results indicate no bivariate or multivariate differences between African American, Hispanic, or White frail older persons in use of community long-term services. Living arrangements, Medicaid use, and overall health and functional status were primary predictors of service use. Taking methodological limitations into account, the results suggest similarity in processes influencing use of community long-term care services for African American and White older persons.

Time to nursing home admission for persons with Alzheimer's disease: the effect of health care system characteristics.

OBJECTIVE: To study the influence of state health care system characteristics on time to nursing home admission (NHA) for persons with Alzheimer's disease (AD). METHOD: Up to nine years of Consortium to Establish a Registry for Alzheimer's Disease (CERAD) data on 639 non-Latino White individuals were merged with longitudinal data from the 28 states in which the CERAD participants resided. The state variables reflected characteristics of each state's long-term care (LTC) system, including Medicaid LTC spending practices and the supply of LTC providers. Cox Proportional Hazards Models with time-varying covariates were used to evaluate the risk factors associated with time to NHA. RESULTS: There was differential influence of state variables by marital status. For unmarried non-Latino White persons with AD, a higher percentage of Medicaid LTC spending on home and community-based services (HCBS) was significantly associated with a longer time to NHA. For married persons, a greater number of home health agencies was associated with a longer time to NHA. Other associations also varied by marital status. CONCLUSION: Study findings support the utility of targeted continued expanded provision of HCBS by states and provide a basis for future research regarding the impact of changing state health care systems on LTC utilization for persons with AD.

Determinants of self-perceived risk for AIDS.

This paper examines self-perceptions of risk for AIDS and factors that contribute to estimations of risk. On the basis of a telephone survey of 1,540 adults age 18 to 60, we address the question: What heuristic factors predict perception of risk for AIDS? Results show that five heuristic categories determine self-perceptions of risk: sexual practices, moral evaluations of people with AIDS, emotional response to AIDS, protective actions in response to AIDS, and demographic characteristics. Number of sexual partners over the past five years and knowledge of sexual partners' past sexual behavior are associated significantly with increased perceptions of risk. Fear of AIDS and worry about one's health also contribute significantly to self-perception of risk, as does shame associated with having AIDS. Asian-Americans and persons with no particular religious affiliation report greater perceptions of risk. These findings call attention to heuristic factors in considering theories of risk and in designing interventions to change preventive actions associated with high risk for AIDS.

Age and the role of symptomatology in readiness to quit smoking.

To develop effective age-appropriate strategies for smoking cessation, it is important to understand factors associated with readiness to quit smoking. This article presents results from an analysis of the role of symptomatology in the decisions to quit smoking among three age groups (18-34, 35-54, and > or = 55 years) from a larger sample of smokers in a managed-care setting. Two measures of readiness to quit smoking were used: stages of change and intention to stop. Using ordinal logistic regression, we found that smokers in the middle and oldest age groups who had experienced at least three of five symptoms in the previous 2 weeks were more likely to be in higher stages of readiness. Regardless of age, smokers who attributed symptoms to smoking were more motivated to try to quit, whereas those who attributed symptoms to aging were less likely to intend to stop smoking. Findings from this study indicate a symptom-based approach to smoking cessation may be a useful strategy, especially in provider-based interventions.

Cervical cancer screening in older women. Issues and interventions.

Although some controversy exists, the Papanicolaou (Pap) smear for cervical cancer screening is widely accepted as an effective mechanism for cancer control. An issue of interest to clinicians and behavioral scientists is the underrepresentation of elderly women in populations screened. It is important for nurses to understand the issues, and hypothesized reasons behind this phenomenon, in order to develop interventions to counteract it. The authors examine this problem from a number of behavioral and clinical perspectives and discuss nursing interventions to improve cervical cancer screening in older women.