Biomedical subjects

R Sturm

Publications and source records attributed to R Sturm.

At least 19 recordsLinked to original sources

PubMed2006

Childhood overweight and elementary school outcomes.

OBJECTIVE: To examine the link between childhood overweight status and elementary school outcomes. DESIGN: Prospective study design: multivariate regression models examining the association between changes in overweight status and school outcomes between kindergarten entry and end of third grade, after controlling for various child, family and school characteristics. SUBJECTS: Nationally representative sample of US children who entered kindergarten in 1998, with longitudinal data on body mass index (BMI) and school outcomes at kindergarten entry and end of third grade. MEASUREMENTS: Wide range of elementary school outcomes collected in each wave including academic achievement (math and reading standardized test scores); teacher reported internalizing and externalizing behavior problems (BP), social skills (self-control, interpersonal skills) and approaches to learning; school absences; and grade repetition. Measurements of height and weight in each wave were used to compute BMI and indicators of overweight status based on CDC growth charts. A rich set of control variables capturing child, family, and school characteristics. RESULTS: Moving from not-overweight to overweight between kindergarten entry and end of third grade was significantly associated (P<0.05) with reductions in test scores, and teacher ratings of social-behavioral outcomes and approaches to learning among girls. However, this link was mostly absent among boys, with two exceptions - boys who became overweight had significantly fewer externalizing BPs (P<0.05), but more absences from school compared to boys who remained normal weight. Being always-overweight was associated with more internalizing BP among girls but fewer externalizing BPs among boys. CONCLUSION: Change in overweight status during the first 4 years in school is a significant risk factor for adverse school outcomes among girls but not boys. Girls who become overweight during the early school years and those who start school being overweight and remain that way may need to be monitored carefully.

Absenteeism↗

PubMed2005

A multi-compartment model for slow bronchial clearance of insoluble particles--extension of the ICRP human respiratory tract models.

To incorporate the various mechanisms that are presently assumed to be responsible for the experimentally observed slow bronchial clearance into the HRTM, a multi-compartment model was developed to simulate the clearance of insoluble particles in the tracheobronchial tree of the human lung. The new model considers specific mass transfer paths that may play an important role for slow bronchial clearance. These include the accumulation of particulate mass in the periciliary sol layer, phagocytosis of stored particles by airway macrophages and uptake of deposited mass by epithelial cells. Besides the gel layer representing fast mucociliary clearance, all cellular and non-cellular units involved in the slow clearance process are described by respective compartments that are connected by specific transfer rates. The gastrointestinal tract and lymph nodes are included into the model as final accumulation compartments, to which mass is transferred via the airway route and the transepithelial path. Predicted retention curves correspond well with previously published data.

Absorption↗

PubMed2005

Body mass index in elementary school children, metropolitan area food prices and food outlet density.

OBJECTIVE: The aim of this study was to examine the association between food prices and food outlet density and changes in the body mass index (BMI) among elementary school children in the USA. METHODS: The Early Childhood Longitudinal Study followed a nationally representative sample of kindergarten children over 4 years. We merged individual-level data to (a) metropolitan data on food prices and (b) per capita number of restaurants, grocery stores and convenience stores in the child's home and school zip code. The dependent variables were BMI changes over 1 and 3 years. We analysed mean changes with least-squares regression, and median changes and 85th percentile changes with quantile regression. We controlled for baseline BMI, age, real family income and sociodemographic characteristics. RESULTS: Lower real prices for vegetables and fruits were found to predict a significantly lower gain in BMI between kindergarten and third grade; half of that effect was found between kindergarten and first grade. Lower meat prices had the opposite effect, although this effect was generally smaller in magnitude and was insignificant for BMI gain over 3 years. Differences across subgroups were not statistically significant due to smaller sample sizes in subgroup analyses, but the estimated effects were meaningfully larger for children in poverty, children already at risk for overweight or overweight in kindergarten, and Asian and Hispanic children. There were no significant effects for dairy or fast-food prices, nor for outlet density, once we had controlled for individual characteristics and random intercepts to adjust standard errors for the sampling design. DISCUSSION: The geographic variation in fruit and vegetable prices is large enough to explain a meaningful amount of the differential gain in BMI among elementary school children across metropolitan areas. However, as consumption information was not available, we cannot confirm that this is the actual pathway. We found no effects of food outlet density at the neighbourhood level, possibly because availability is not an issue in metropolitan areas.

Body Mass Index↗

PubMed2005

3D-Visualization of particle deposition patterns in the human lung generated by Monte Carlo modeling: methodology and applications.

An advanced stochastic model is described which enables the generation of three-dimensional particle deposition patterns in the human lung. While particle trajectories are represented as a combination of randomly oriented vectors in a coordinate system with the trachea defining the z direction, deposition sites of single particles are determined by using a grid of specific volume elements (voxels). After storage in an array, the spatial coordinates are visualized with an appropriate graphic editor, enabling the combination of respective deposition images with lung outlines and the creation of two-dimensional distributions by sectioning the three-dimensional structures at pre-defined positions.

Aerosols↗

PubMed2004

Multi-channel magnetocardiography for detecting beat morphology variations in fetal arrhythmias.

OBJECTIVE: Over the last few years, a number of studies have shown that fetal magnetocardiography (fMCG) is useful in describing fetal cardiac activity. A 55-channel MCG system in Ulm was used to record fetal cardiac activity in 12 pregnant women (with normal fetal heart activity in echocardiography) and in 5 pregnant women in whom the echocardiography showed fetal arrhythmias. METHOD: The recorded MCG data were treated in order to eliminate the maternal signal and three MCG channels with the best signals were used to emulate a standard electrocardiogram (ECG) recording so that standard MCG analysis could be performed. RESULTS: The results in assessing fetal electrophysiology, demonstrating its potential, are presented here for two fetuses with recorded supraventricular extrasystoles (SVES) and for one with ventricular extrasystoles (VES). Concerning the SVES, the analysis software OMEGA was able to separate three different beat morphologies. The VES could be detected exactly and have been confirmed by postnatal ECG. CONCLUSION: The beat morphology and the beat-to-beat variations allow new insights into the electrophysiology of the fetal heart.

Arrhythmias, Cardiac↗

PubMed2004

Imaging of growth banding of minerals using 2-stage sectioning: application to accessory zircon.

In the past, investigations of mineral growth were routinely carried out by the application of light-microscopic methods and, later on, by the production of single crystal sections and their documentation using specific imaging techniques (CL, BSEI, etc.). In the present work, a method is described which enables the precise sectioning of elongate crystals parallel and perpendicular to their longest axis. By examining backscattered electron images of parallel and perpendicular sections of the same grain, growth of all faces may be evaluated without major geometric correction. The new technique is applied to zircon crystals of a granitoid exposed in the southwestern Bohemian Batholith, Austria. For the studied zircon population, pyramidal and prism development during crystal growth is worked out very clearly by the imaging procedure. Besides its significance in crystal studies, the introduced method could also find a use in material science for the growth study of synthetic mineral phases.

Journal Article↗

PubMed2004

Suburban sprawl and physical and mental health.

OBJECTIVE: To study the association between objective measures of suburban sprawl and chronic medical conditions and mental health disorders in the USA. METHODS: Cross-sectional analysis of survey data merged with objective measures of suburban sprawl. Outcomes are self-reported medical conditions, mental health disorders and health-related quality of life. RESULTS: Sprawl significantly predicts chronic medical conditions and health-related quality of life, but not mental health disorders. An increase in sprawl from one standard deviation less to one standard deviation more than average implies 96 more chronic medical problems per 1000 residents, which is approximately similar to an aging of the population of 4 years. CONCLUSIONS: A robust association between sprawl and physical (but not mental) health suggests that suburban design may be an important new avenue for health promotion and disease prevention.

Adult↗

PubMed2004

Stochastic simulation of alveolar particle deposition in lungs affected by different types of emphysema.

In the present study, disease-specific stochastic models were developed for the computation of particle deposition in lungs affected by COPD, emphysema, or both, distinguishing between four types of pulmonary emphysema-centriacinar, paraseptal, panacinar, and bullous. To simulate COPD, airway calibers of the tracheobronchial tree were randomly reduced between 20% and 50% in each airway. For the study of pure COPD ("blue bloaters"), alveolated airway dimensions of the healthy lung were used, while for the simulation of emphysema without COPD ("pink puffers"), normal conductive airway diameters were assumed. Deposition calculations in diseased lungs were carried out by assuming (a) identical inspiration and expiration times (no breath-hold time) and (b) a continuous increase of the functional residual capacity (from 3,300 to 5,000 mL), accompanied by a simultaneous drop of the tidal volume (from 1,000 to 500 mL). Independent of particle size, total alveolar deposition in emphysematous lungs was significantly decreased relative to normal lungs. In particular, the deposition maximum at large particle sizes, which is a characteristic for healthy subjects, completely disappeared. Among the various emphysema models, deposition was smallest in lungs with bullous emphysema due to strongly enhanced settling and diffusion distances within the alveolar structures. A change of the lung volume caused a further decrease in particle deposition. Alveolar deposition in "blue bloaters" and "pink puffers" was very similar to the deposition in patients suffering from COPD and emphysema. Alveolar deposition per acinar airway generation was also strongly reduced in diseased lungs compared to normal lungs. Besides this reduction, deposition patterns became more uniform throughout the alveolar region.

Aerosols↗

PubMed2003

Mechanistic interpretation of the slow bronchial clearance phase.

A slow bronchial clearance phase, describing the removal of insoluble particles from the sol layer, has recently been incorporated into the ICRP human respiratory tract model. A striking feature of that clearance phase is the size dependence of the slowly cleared fraction. In the theoretical approach presented here, it is suggested that the slow bronchial clearance phase includes three main mechanisms: (1) re-transfer of particles onto the gel layer after a certain time delay, (2) intra- or intercellular transfer of particles through the airway epithelium and subsequent transport to the blood or lymph nodes, and (3) uptake of particles by airway macrophages. The experimentally observed inverse relationship between the slow clearance fraction and geometric particle size is interpreted as an increasing capture probability in the sol layer and transepithelial transport with decreasing particle diameter.

Absorption↗

PubMed2003

Simulation of deposition and clearance of inhaled particles in central human airways.

In this study local distributions of deposited inhaled particles such as radon progenies in realistic human airway bifurcation models of bronchial generations one to six are computed for different geometries, inlet flow profiles, flow rates and particle sizes with computational fluid particle dynamics methods. The movement of the mucus layer in the large central human airways is also simulated by computational fluid dynamic techniques. There is experimental evidence that bronchogenic carcinomas mainly originate at the central zone of the large airway bifurcations, where primary hot-spots of deposition have been found. However, current lung deposition models do not take into consideration the inhomogeneity of deposition within the airways. The inhomogeneous movement of the mucus layer may strongly influence the effect of primary deposition. On the basis of our results, both the deposition and the clearance patterns are highly non-uniform, especially in the vicinity of the carinal ridge of the bifurcations.

Absorption↗

PubMed2003

Stochastic model of ultrafine particle deposition and clearance in the human respiratory tract.

Deposition and clearance of insoluble ultrafine particles, ranging from 1 to 100 nm, were simulated by stochastic models using Monte Carlo methods. Brownian motion is the dominant mode of deposition in human airways. The additional effects of convective diffusion in bifurcations and axial diffusion (convective mixing) primarily affect particle transport and deposition of particles in the 1-10 nm range. Regarding total deposition, the effects of both convective mechanisms are practically compensated by the concomitant effect of molecular radial diffusion (Brownian motion). During the first hours following inhalation, 1 nm particles are predicted to be cleared much faster than particles in the size range from 10 to 100 nm, with a retained fraction of about 80% after 24 h. For 1-10 nm particles, extracellular transfer to blood is the most likely mode of clearance, while uptake and subsequent accumulation in epithelial cells are assumed to be the preferential mechanisms for 10-100 nm particles.

Adsorption↗

PubMed2002

Application of a 1.48-microm diode laser for bisecting oocytes into two identical hemizonae for the hemizona assay.

Laser systems are very promising new technical tools in assisted reproduction. It was investigated if laser radiation can replace the mechanical cutting procedure via micromanipulator in the hemizona assay (HZA), a commonly used bioassay to determine the sperm-zona pellucida binding capacity. An oocyte was bisected precisely into two identical hemizonae with approximately 20 laser pulses (pulse length 30 msec) using a 1.48-microm diode laser. Compared with the conventional method using microscalpels for zona bisection, laser treated hemizonae showed equivalent sperm-binding and within the two groups there was no detectable difference between matching hemizonae in their capacity for tight sperm-binding. To evaluate whether laser radiation affects the outcome of the HZA when effects of certain substances are investigated, the spermatozoa were preincubated with human follicular fluid (hFF), which inhibits the binding of spermatozoa to zona pellucida in vitro. Supplementation with follicular fluid exerted an inhibitory effect in both groups. The hemizona index (HZI) showed no statistical differences between the two methods. Therefore, the 1.48-microm diode laser is a suitable new instrument for generating equally sized hemizonae. There is no use for holding pipettes and microscalpels, on the contrary, for performing the HZA the laser is a precise, very quick and easy to use new working tool.

Female↗

PubMed2001

Are barriers to mental health and substance abuse care still rising?

This study estimates unmet need and barriers to alcohol, drug, and mental health (ADM) services in 1997 to 1998 using data from a national household survey (n = 9,585). In 1997 to 1998, 10.9% of the population perceived a need for ADM services, with 15% obtaining no treatment and 11% experiencing delays or obtaining less care than needed. The rate of unmet need due to no treatment is similar to earlier studies, but the group experiencing delays/less care is almost as large. This finding emphasizes the importance of defining access to care more broadly by including timeliness and intensity of care. Economic barriers are highest for the uninsured, but also are high among the privately insured. Individuals with unmet need are significantly more likely to use complementary and alternative medicine (CAM). Those with no conventional mental health care rely on self-administered treatment, while those with delayed/insufficient conventional care use CAM providers and self-administered treatment.

Complementary Therapies↗

PubMed2001

National estimates of mental health utilization and expenditures for children in 1998.

No recent national data on expenditures and utilization are available to provide a benchmark for reform of mental health systems for children and adolescents. The most recent estimates, from 1986, predate the dramatic growth of managed care. This study provides updated national estimates. Treatment expenditures are estimated to be $11.68 billion ($172 per child). Adolescents have the highest expenditures at $293 per child followed by $163 per child aged 6 to 11 and $35 per preschool-aged child. Outpatient services account for 57%, inpatient for 33%, and psychotropic medications for 9% of the total. Unlike earlier reports, outpatient care now accounts for the majority of expenditures. This finding replicates the differences between recent managed care data and earlier actuarial databases for privately insured adults and confirms the trend from inpatient toward outpatient care.

Adolescent↗

PubMed2001

Gonadotropin-releasing hormone antagonist protocol: a novel method of ovarian stimulation in poor responders.

OBJECTIVE: To estimate the efficacy of gonadotropin-releasing hormone (GnRH) antagonist 'Cetrorelix' in poor responders comparing with the standard long protocol. DESIGN: The study population consisted of 21 poor responders who underwent ICSI and treated with Cetrorelix according to the multiple-dose protocol and who were compared with 21 poor responders treated according to the long protocol and who also underwent ICSI. Patients in both groups were matched for chronological age, the number of follicles found by ultrasound at the retrieval day and cause of infertility. Fifteen patients of GnRH antagonist group were treated with the combination of GnRH antagonist with clomiphene citrate (CC) plus gonadotropins, while six patients were treated with the combination of GnRH antagonist plus gonadotropins, but without CC. RESULTS: The use of GnRH antagonist in a multiple dose protocol gave a pregnancy rate of 14.28% which was in the range expected for patient with poor response, but with shorter treatment duration and with fewer ampoules of gonadotropins as compared with the use of a GnRH agonist protocol in a depot formulation. Within Cetrorelix group patients who received CC had a significant shorter duration of stimulation and needed fewer ampoules as compared with patients in the same group who did not receive CC. CONCLUSIONS: A GnRH antagonist multiple dose protocol may be the protocol of choice for the treatment of poor responders. The use of GnRH antagonist Cetrorelix ended with significantly less ampoules of gonadotropins and a shorter duration of stimulation.

Adult↗

PubMed2001

Does the sunset of mental health parity really matter?

The 1996 Mental Health Parity Act (MHPA), which became effective in January 1998, is scheduled to expire in September 2001. This article provides an overview of what the MHPA intended to do and what it actually has accomplished. We summarize state legislature actions through the end of 2000 and report on their effects on employer-sponsored mental health coverage using a national survey fielded in 1999-2000. We then discuss possible amendments to the MHPA and reforms beyond full parity that might be considered.

Health Benefit Plans, Employee↗

PubMed2001

Does obesity contribute as much to morbidity as poverty or smoking?

The prevalence of obesity is increasing in America, but its impact on morbidity relative to other health risks is unclear. This paper compares the effects of overweight, poverty, smoking and problem drinking on occurrence of chronic conditions and health-related quality of life. The data were collected from a nationally representative household telephone survey of 9585 adults fielded in 1998, using self-reported measures of height and weight, poverty, smoking status, problem drinking, chronic conditions and SF-12 global scales. Regression analyses were used to estimate effects of health risk factors on morbidity. Thirty-six percent of adults are overweight but not obese (25< or =BMI<30) and another 23% are obese (BMI> or =30). Controlling for demographics, obesity is associated with more chronic conditions and worse physical health-related quality of life (P<0.01). Smoking history and poverty predict having chronic conditions, but their effect sizes are significantly smaller. Even after controlling for chronic conditions, obesity predicts physical health-related quality of life, in that case with an effect size similar to poverty. The effect of problem drinking is always smaller. Obesity is highly prevalent and associated with at least as much morbidity as are poverty, smoking and problem drinking. Nevertheless, the latter have achieved more consistent attention in recent decades in clinical practice and public health policy.

Body Mass Index↗

PubMed2001

Effects of cost-containment strategies within managed care on continuity of the relationship between patients with depression and their primary care providers.

BACKGROUND: Continuity of the relationship between patients and primary care providers (PCPs) is an important component of care from the consumer perspective that may be affected by variation in cost containment strategies within managed care. OBJECTIVE: To evaluate the effects of cost containment strategies on the continuity of the relationship between their patients with depression and their PCPs. DESIGN: Observational analysis of a 2-year panel of depressed patients who participated in a quality improvement intervention trial in 46 managed care practices. PARTICIPANTS: One thousand two hundred four patients with current depression who enrolled in a longitudinal study, completed the baseline survey, and were followed for 2 years. MAIN MEASURES: The dependent variable is probability of continuing the relationship between patients and their PCPs; explanatory variables include individual patient mental health benefits and cost-sharing, individual provider financial incentives, supply-side managed care policies, and patient ratings of the care received. RESULTS: The average duration of the patient-PCP relationship was significantly longer among depressed patients who initially had less generous benefits for specialty care (higher copays, P = 0.02 and fewer visits covered, P = 0.002) and for patients whose PCPs received a performance-based salary bonus from a risk pool (P = 0.07). CONCLUSIONS: For depressed patients, cost containment strategies, such as limits on specialty benefits and presence of clinician bonus payments typically used within managed care may increase, rather than decrease, PCP continuity. Whether increased PCP continuity is a desirable outcome depends on whether health care systems can provide high quality primary care and this merits further study.

Adult↗