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PubMed2001

Incisor and mandibular condylar movements of young adult females during maximum protrusion and lateratrusion of the jaw.

This study evaluated the correlations between condylar translation and incisor movements during maximum protrusion and lateratrusion. The sample was 27 adult females (23--35 years old), selected for normal temporomandibular function, occlusion, and skeletal patterns. Condylar and mandibular central incisor movements [linear distances (LD) and curvilinear pathways (CP)] were recorded in three dimensions for 20 s with an optoelectric (Optotrak) jaw-tracking system while each participant performed multiple maximum protrusive and lateratrusive cycles. Masticatory analysis and multilevel statistical programs computed the three-dimensional movements of the incisors and condylar hinge axis during protrusion and lateratrusion. CP of the incisor point averaged 12.0 mm (9.3 mm LD) during protrusion, 13.0 mm (11.5 mm LD) during right excursion and 12.3 mm (11.0 mm LD) during left excursion. CP of the condyles averaged 11.9--12.9 (9.2--9.5 LD) mm during protrusion. During lateratrusion the contralateral condyles moved anteroinferiorly 11.6--14.1 mm (9.5--10.2 mm LD); the ipsilateral condyles moved posterolaterally 5.8-6.8 mm (2.3--2.5 mm LD). The left condyles demonstrated more movement than the right condyles during protrusion and than the contralateral condyles during laterotrusion. Relative variation, as measured by the coefficient of variation, was greater for the movements of the ipsilateral than contralateral condyles. Incisor movements were only moderately related to condylar movements between individuals and between replicates; LDs showed stronger correlations than CPs; and correlations were stronger for lateratrusion than protrusion. While incisor and condylar movements were not affected by repeated protrusion, incisor CP (approx. 0.2 mm/cycle) and LD (approx. 0.1 mm/cycle) increased significantly with repeated excursive movements to the left and right. It was concluded that (1) incisor protrusion and lateratrusion provide moderately reliable measures of condylar translation; (2) the linear distances that the incisors move during lateratrusion provide the best measure of contralateral condylar translation; and (3) condylar movements are not affected by repeated protrusion or lateratrusion.

Adult↗
PubMed2000

Associations between incisor and mandibular condylar movements during maximum mouth opening in humans.

This study evaluated the common clinical assumption that condylar translation and mouth opening at the incisor are closely related. The sample studied comprised 27 adult females (23-35 years), selected for normal temporomandibular function, occlusion, and skeletal patterns. Condylar and mandibular central incisor movements (straight-line distances and curvilinear pathways) were recorded in three dimensions (3D) for 20 s with an optoelectric (Optotrak(R)) jaw-tracking system while each participant performed multiple maximum opening cycles. Masticatory analysis and multilevel statistical programs computed the 3D movements of the incisors and condylar hinge axis during opening and closing. The incisor point moved an average straight-line distance of 46.6 mm during opening and 45.9 mm during closing; the lengths of the opening and closing curvilinear pathways were 48.6 and 47.7 mm, respectively. The condyles moved average straight-line distances of 11.9 and 12.2 mm during opening and closing, respectively. The condyles' curvilinear pathways during opening and closing were 14 and 14.6 mm, respectively. Ranges of condylar movement varied widely between individuals. The straight-line distances and curvilinear pathways were highly correlated for the incisors (R=0.98) and the condyles (R=0.98). Neither the straight-line distances nor curvilinear pathways of the incisors were correlated with those of the condyles. Incisor straight-line distances and curvilinear pathways were moderately correlated with mandibular rotation (R(between subjects)=0.82 and R(between repeats)=0.88). During repeated openings, both condylar and incisor excursions increased, but during repeated closings only incisor excursions increased. It is concluded that (1) maximum incisor opening does not provide reliable information about condylar translation and its use as a diagnostic indicator of condylar movement should be limited, (2) healthy individuals may perform normal opening with highly variable amounts of condylar translation, (3) the straight-line distances of the incisor and condyles provide adequate information about the length of the curvilinear pathway, and (4) variation in maximum incisor opening is largely explained by variation in the amount of mandibular rotation.

Adult↗
PubMed1999

Low uptake of eye services in rural India: a challenge for programs of blindness prevention.

OBJECTIVES: To investigate service uptake in a rural Indian population served by outreach eye camps and to identify barriers to uptake. PARTICIPANTS AND METHODS: A routine eye camp was conducted within 5 km of each of 48 randomly selected villages of typically Hindu, backward-caste communities. Subsequently, participatory rural appraisal-community mapping, focus groups, matrix ranking, and semistructured interviews-was undertaken to explore community views of eye problems. An eye examination was conducted on persons with eye problems who did not attend the eye camp. Predictors of attendance were identified by multilevel regression analysis. RESULTS: Of 749 adults with an eye problem, 51 (6.8%) attended the eye camp. Independent predictors of attendance were being male (odds ratio = 2.3; 95% confidence interval, 1.2-4.5) and living within 3 km of the camp (odds ratio = 4.5; 95% confidence interval, 1.7-12.5). Of the 552 persons who did not attend the eye camps and had an eye examination, 242 (43.8%) had low vision (visual acuity <6/18 to > or =3/60 in presenting better eye) and 38 (6.9%) were blind in both eyes. Cataract surgery was recommended for 197 (35.8%) of the persons who did not attend the eye camps. Of 109 persons with a previous cataract operation, 42 (38.5%) had low vision and 11 (10.1%) were blind. Fear (principally of eye damage), cost (direct and indirect), family responsibilities, ageism, fatalism, and an attitude of being able to cope (with low or no vision) were the principal barriers to attending the eye camps. CONCLUSIONS: A high proportion of people who could have benefited from eye treatment were not using available services. Poor visual outcomes were observed in surgically treated persons.

Attitude to Health↗
PubMed2006

Longitudinal follow-up of fitness during childhood: interaction with physical activity.

Health-related fitness values during childhood (from age 11 to 16 years) were analyzed in relation to changes in physical activity level. One hundred fifty-eight children were monitored over a 4-year period. Twice a year, they performed six physical fitness tests: standing broad jump, 10 x 5-meter shuttle run, sit-and-reach, handgrip, number of sit-ups in 30 s, and 20-m shuttle run. Height was measured four times per year to assess age at peak height velocity. Physical activity was assessed with a self-administered questionnaire at baseline and at the end of the follow-up. The physical activity level was defined by the frequency and the time spent in moderate-to-vigorous physical activities. Two groups were constituted: regularly active and sedentary. A multiple linear multilevel regression analysis was used to analyze the longitudinal relationships between changes in physical activity and physical fitness levels. Corrections were made for both time-dependent (time) and time-independent (sex) variables. Except for flexibility, boys' fitness performances increased more than that for the girls. Positive and significant (P < 0.05) regression coefficients were found with the regularly active for standing broad jump, 20-m shuttle run, number of sit-ups, 10 x 5-m shuttle run in both sexes, and for the girls' sit-and-reach performance. Increasing or decreasing physical activity level was not associated with changes in fitness performances over time, except for flexibility for the girls and the 20-m shuttle run for the boys. From childhood to adolescence, increasing physical activity is not sufficient to be more fit. The children who are stayed the most active were the fittest, particularly the girls. Am. J. Hum. Biol. 18:51-58, 2006. (c) 2005 Wiley-Liss, Inc.

Adolescent↗
PubMed1996

Multilevel models for longitudinal variables prognostic for survival.

The issue of modelling the joint distribution of survival time and of prognostic variables measured periodically has recently become of interest in the AIDS literature but is of relevance in other applications. The focus of this paper is on clinical trials where follow-up measurements of potentially prognostic variables are often collected but not routinely used. These measurements can be used to study the biological evolution of the disease of interest; in particular the effect of an active treatment can be examined by comparing the time profiles of patients in the active and placebo group. It is proposed to use multilevel regression analysis to model the individual repeated observations as function of time and, possibly, treatment. To address the problem of informative drop-out--which may arise if deaths (or any other censoring events) are related to the unobserved values of the prognostic variables--we analyse sequentially overlapping portions of the follow-up information. An example arising from a randomized clinical trial for the treatment of primary biliary cirrhosis is examined in detail.

Bilirubin↗
PubMed1986

An automated technique for analysis of current transitions in multilevel single-channel recordings.

Detailed kinetic studies of ion channel gating are best carried out using the patch-clamp technique which permits the measurement of the ionic current through individual channels. Typical patch-clamp recordings show the current signal, in the form of a sequence of rectangular pulses (analogous to a random telegraph signal), riding on slow baseline drift, partially obscured by high-frequency noise and distorted by filtering. In order to analyze such recordings, we have developed a set of interactive Pascal programs based on a feature-detection algorithm capable of identifying current transitions in multiple-channel recordings in the presence of substantial levels of noise and drift. Software operation is largely automated but includes provisions for examination and correction of the output. The software was optimized and systematically evaluated using simulated data with variable amounts of noise and drift. Results indicate that satisfactory performance is obtained for signal-to-noise ratio as low as four even with uncommonly large baseline drift. Steady-state processing speeds varied from 1,000 to 4,000 samples per second depending on data complexity.

Automation↗
PubMed1987

Prevention and ecology: teen-age pregnancy, child sexual abuse, and organized youth sports.

A multilevel ecological analysis of issues that impact on children and families is advocated as the best theoretical framework for conceptualizing preventive interventions. Teen-age pregnancy and child sexual abuse are discussed as targets of preventive intervention: the former being an issue about which we have much information that has not been adequately used, whereas the latter is one about which we have too little information to be mounting the sweeping prevention programs that are rapidly coming into existence. Organized youth sports is then discussed as a neglected societal vehicle for prevention.

Adolescent↗
PubMed2001

Associations between nonshared environment and child problem behaviour.

BACKGROUND: Twin studies suggest that environmental effects on the development of child psychopathology largely involve nonshared environmental processes. However, the influence of the nonshared environment may have been overestimated, as the relationship between environment and behaviour may be genetically mediated. A direct measure of the nonshared environment (using the Sibling Inventory of Differential Experience - SIDE) was investigated in relation to child psychopathology, and tested for possible genetic mediation. METHOD: Parent-rated versions of the Child Behaviour Checklist (CBCL) and the SIDE were collected in 760 twin pairs aged 6-17 years. Multilevel regression analysis was used to assess the influence of SIDE scores on CBCL total problem scores, internalising symptoms, externalising symptoms and depressive symptom scores. Genetic mediation was assessed by examining interaction with zygosity in the association between SIDE scores and differences in CBCL scores (absence of interaction indicating no genetic mediation). RESULTS: The results revealed significant associations between SIDE dimensions on the one hand, and degree of internalising, externalising, depression and total symptom scores on the other. However, the effects were non-linear, and especially apparent for the extremes of differential environmental experience within twin pairs. Overall, there was no strong evidence for genetic mediation of associations between nonshared environment and symptoms. CONCLUSIONS: Direct, genetically unconfounded but skewed relationships may exist between nonshared environment on the one hand and behavioural differences on the other, although longitudinal data are necessary to determine the direction of effects.

Adolescent↗
PubMed2005

Course of gross mechanical efficiency in handrim wheelchair propulsion during rehabilitation of people with spinal cord injury: a prospective cohort study.

OBJECTIVE: To investigate the course of mechanical efficiency of handrim wheelchair propulsion during rehabilitation of subjects with (in)complete paraplegia and tetraplegia. DESIGN: Subjects were tested at the start of active rehabilitation (t1), 3 months later (t2), and when discharged from inpatient rehabilitation (t3). They performed two 3-minute submaximal treadmill exercise blocks in a wheelchair. SETTING: Eight rehabilitation centers in the Netherlands. PARTICIPANTS: Ninety-two people with (in)complete paraplegia and tetraplegia. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mechanical efficiency values were calculated for each block. The course of mechanical efficiency was investigated using test occasions (t1 -t3), completeness and level (paraplegia or tetraplegia) of the lesion, and power output as independent variables in a multilevel regression analysis. RESULTS: Mechanical efficiency significantly increased between t1 and t2 only. After adding level and completeness of the lesion and their interactions with time to the model, block 2 showed that subjects with paraplegia had a significantly higher mechanical efficiency than subjects with tetraplegia. Subjects with tetraplegia improved more between t1 and t2 . Differences in mechanical efficiency between subjects with paraplegia and tetraplegia could not be explained by differences in absolute and relative power output levels. CONCLUSIONS: Results showed a significant improvement in mechanical efficiency during the first 3 months of active rehabilitation. Subjects with paraplegia showed a higher mechanical efficiency than did subjects with tetraplegia, whereas the latter showed more improvement between t1 and t2 .

Acceleration↗
PubMed2006

Quality of life of stroke survivors: a 1-year follow-up study.

OBJECTIVES: To examine the changes in and to identify determinants of health-related quality of life (HRQOL) during the first year after stroke. DESIGN: Prospective cohort study. SETTING: Regional university teaching hospital in China. PARTICIPANTS: Chinese survivors of stroke (N=303). Patients who were previously physically handicapped were excluded. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Barthel Index, Lawton Instrumental Activities of Daily Living (IADL), Chinese Mini-Mental State Examination, Geriatric Depression Scale (GDS), and the abbreviated Hong Kong Chinese version of the World Health Organization Quality of Life measure domain scores at 3, 6, and 12 months after the stroke. RESULTS: A total of 268 (88%) subjects completed the study. HRQOL data were available in 247 (82%) subjects at 3 months. Between 3 and 12 months, there was no significant change in Barthel Index and IADL scores, but there was significant increase in GDS scores. On multivariate analysis and multilevel modeling, there was a small but significant decrease in social interaction and environment HRQOL domain scores with time. GDS score was negatively associated with all 4 domains of HRQOL, whereas the Barthel Index score was associated with physical and psychological HRQOL domains only. Female sex, nursing home residence, welfare assistance, pain in affected limbs, soft diet or tube feeding, and lack of physical exercise were associated with poorer HRQOL. CONCLUSIONS: Environment and social interaction HRQOL may decrease after 1 year of stroke among Chinese stroke patients. Depression has a more generalized adverse effect on HRQOL than basic functional disabilities. Health care professionals should focus on treating depression; group exercises and self-help group activities may help in promoting socialization and reintegration into community life.

Activities of Daily Living↗
PubMed2005

Introduction of diabetes passports involving both patients and professionals to improve hospital outpatient diabetes care.

AIM: To investigate whether a comprehensive strategy involving both patients and professionals, with the introduction of a diabetes passport as a key component, improves diabetes care. METHODS: The first 150 consecutive patients who visited their internist for a diabetes check up at the internal medicine outpatient departments at each of nine Dutch general hospitals were included in this 1 year clustered, randomised, controlled trial. Health care professionals attended an educational meeting about the use and dissemination of the diabetes passport which is a patient held record. They also received aggregated feedback on baseline data and personal feedback. Educational meetings were also organised for patients. Patient files were used in conjunction with questionnaires to determine adherence rates. Data were analysed using multilevel regression analysis. RESULTS: Small but significant changes were found in mean HbA1c levels. In the intervention group, positive health changes for patients were found (-0.3%) when compared to those in the control group (+0.2%). Diastolic blood pressure improved slightly, but no changes were found in systolic blood pressure or cholesterol. Improvements were found with regard to levels of examination of patients' feet and in patient education. CONCLUSIONS: Efforts to improve professional practice involving both professionals and patients led to small improvements in HbA1c and diastolic blood pressure levels. Further study is needed to establish whether a better structured health care delivery, operating in a more supportive environment can enhance these effects.

Ambulatory Care↗
PubMed2005

Maternal and child health and neighborhood context: the selection and construction of area-level variables.

BACKGROUND: Increasingly, maternal and child health researchers are employing the statistical approach of multilevel modeling analysis to simultaneously examine the relationship between contextual and individual determinants and maternal and child health outcomes. This review addresses the following questions: (1) What categories of neighborhood characteristics have been addressed? (2) How were those neighborhood characteristics operationalized? METHODS: A literature review identified 31 relevant articles published between January 1999 and March 2004. The articles were read with special attention toward the measurement of neighborhood characteristics. RESULTS: Twelve categories of neighborhood characteristics represented in the articles include income/wealth, employment, family structure, population composition, housing, mobility, education, occupation, social resources, violence and crime, deviant behavior and physical conditions. A wide diversity of approaches was used to measure these characteristics. The most widely utilized source of data was that of administrative records from the census or local government authorities. Although most authors provided theoretical explanations of their choice to examine broad neighborhood constructs, few were explicit about why certain indicators were selected to measure these constructs. CONCLUSIONS: There are theoretical, methodological and practical barriers in the measurement of the neighborhood context which must be addressed for the field to move forward. These barriers are discussed and recommendations are made for addressing them in future research.

Adolescent↗
PubMed2005

Field demonstration of surfactant-enhanced solubilization of DNAPL at Dover Air Force Base, Delaware.

This study reports on a surfactant-based flood for tetrachloroethylene (PCE) removal from a control test cell at the Dover National Test Site. The surfactant formulation (sodium dihexyl sulfosuccinate (Aerosol-MA or AMA), isopropanol and calcium chloride) was able to achieve a high concentration of PCE in swollen micelles (supersolubilization) without vertical PCE migration. The hydraulic system included eight screened wells that were operated in both vertical circulation and line drive configurations. After 10 pore volumes of flushing, the overall PCE removal was 68% (65% of which corresponded to the surfactant flooding alone). In addition, the residual PCE saturation was reduced from 0.7% to 0.2%, and the concentration of PCE in the groundwater was reduced from 37-190 mg/L before the flushing to 7.3 mg/L after flooding. Recycling the surfactant solution reduced the required surfactant mass (and thus cost, and waste) by 90%. Close to 80% of the total PCE removal was obtained during the first five pore volumes which were operated in an upward vertical circulation flow scheme. No free oil phase was observed during the test. Further analysis of multilevel sampler data suggests that most of the trapped oil remaining in the cell was likely localized in secluded regions of the aquifer, which helps explain the lower PCE groundwater concentration after remedial activities. In summary, this field study demonstrated the feasibility of surfactant-enhanced remediation to reduce the mass in the source zone and significantly reduce the PCE aqueous concentration and therefore the risk associated with the contaminant plume.

2-Propanol↗
PubMed2006

Childhood trauma and emotional reactivity to daily life stress in adult frequent attenders of general practitioners.

OBJECTIVES: Childhood trauma (CT) has consistently been associated with neuroticism--a personality trait reflecting vulnerability to stress. However, not much is known about the impact of a history of trauma on moment-to-moment emotions and experiences in the flow of daily life. The relationship between CT and emotional reactivity to daily life stress was investigated. METHODS: Ninety frequent attenders of general practitioners, of which 29 fulfilled criteria for CT (sexual and/or physical trauma before the age of 19 years), were studied with the Experience Sampling Method (a structured diary technique assessing current context and mood in daily life) to assess: (a) appraised subjective stress related to daily events and activities, and (b) emotional reactivity conceptualized as changes in negative affect (NA). RESULTS: Multilevel regression analysis revealed that subjects with a history of CT reported significantly increased emotional reactivity to daily life stress, as reflected in an increase in NA. This effect was significantly stronger for subjects who experienced trauma before the age of 10 years. CONCLUSION: These results confirm that CT may have long-lasting and enduring effects on adult psychological functioning, as exposed individuals continually react more strongly to small stressors occurring in the natural flow of everyday life. The finding that emotional stress reactivity is most pronounced for subjects who experienced trauma early in life confirms prior evidence suggesting that the effects of trauma are more detrimental when trauma occurs at a younger age.

Adaptation, Psychological↗
PubMed2004

Challenging the cholinergic system in mild cognitive impairment: a pharmacological fMRI study.

Mild cognitive impairment (MCI) often represents an early form of Alzheimer disease (AD). In both MCI and AD, characteristic cholinergic changes may occur. Functional magnetic resonance imaging (fMRI) may help to examine neurochemical changes in early disease by studying signal reactivity to pharmacological challenge. In this study, MCI patients [n=28; mean age 73.6+/-7.5; mini mental state examination (MMSE) 27.0+/-1.2] were scanned during task performance in a randomized trial under three different medication regimes: at baseline [BL; no galantamine (GAL)], after a single oral dose of GAL (SD), and after prolonged exposure (steady state: SS). Memory tasks included an episodic face-encoding task and a parametric n-letter back working memory (WM) task. Alterations in brain activation patterns before and after treatment were analyzed for both tasks using multilevel statistical analysis. Significant increases in brain activation from BL were observed after prolonged exposure only. For face encoding (n=28), these involved left prefrontal areas, the anterior cingulate gyrus, left occipital areas, and left posterior hippocampus. For working memory (n=28), increased activation was found in right precuneus and right middle frontal gyrus, coinciding with increased accuracy scores after GAL treatment. In conclusion, cholinergic challenge produces alterations in brain activation patterns in elderly MCI patients that can be detected with fMRI. This should encourage further functional imaging studies to examine the status of neurotransmitter systems in disease.

Administration, Oral↗
PubMed2004

Comparison of the breeding performance of cows in cold and warm loose-housing systems in Finland.

Finland's cold loose-housing systems for dairy cows were compared with the more traditional warm loose-housing systems regarding the number of days from calving-to-first-service, the first-service-pregnancy risk and the repeated-service-conception hazard. 3131 calvings registered during the indoor periods in 1996 and 1997 on 208 farms were modelled using multilevel survival analysis and logistic regression in a retrospective cohort study. Compared to cows in a warm loose-housing system, cows in a cold loose-housing system had the same period from calving-to-first-service, a significant 6% lower first-service-pregnancy risk and the same repeated-service-conception hazard.

Animals↗
PubMed2004

Levels and variability of daily life cortisol secretion in major depression.

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is an important feature of major depressive disorder (MDD), but relatively little attention has been given to within-person variability of hormone secretion over time. Because most studies have been conducted in hospital settings, little information is available about naturally occurring patterns of cortisol secretion throughout the day in depressed outpatients. Multiple salivary cortisol samples were obtained over a 6-day period from 47 outpatients with MDD and 39 healthy controls in their everyday environment. We used multilevel regression analysis to estimate the effects of MDD and associated clinical characteristics on cortisol levels and intraindividual variability. Although more severe symptoms were associated with small elevations in cortisol levels, we found no clear evidence for hypercortisolism in the MDD group as a whole. However, cortisol output in MDD outpatients was less stable from sample to sample, as evidenced by a significantly lower autocorrelation than that observed in controls. Secretory patterns were particularly erratic in patients with more severe or recurrent episodes. Findings suggest that erratic cortisol secretion may be a more characteristic feature of HPA axis dysregulation in MDD than hypercortisolism, especially in outpatient populations.

Adolescent↗
PubMed2006

A longitudinal study on cortisol and complaint reduction in burnout.

Several studies have investigated the association between burnout and HPA-axis functioning, but the results are far from consistent. This does not preclude the possibility that within a group of burnout patients a recovery of symptoms in a longitudinal course corresponds to (changes in) cortisol parameters. The latter possibility is tested in the present study before and after treatment, and at follow-up. HPA-axis functioning and burnout complaints were assessed in burned-out participants at baseline (n=74), post-treatment (n=62) and at follow-up (n=53). Multilevel regression analysis was used to test the hypothesis. Burnout complaints were significantly reduced at 8.5 months post-treatment, but there was no further reduction in complaints at follow-up 6.3 months later. Cortisol after awakening, and after dexamethasone intake showed no changes from baseline to post-treatment and follow-up. There was a small decline in cortisol during the day over the longitudinal course. The cortisol level after awakening in the longitudinal course showed significant positive association with the initial exhaustion level, a negative association with the change in the burnout exhaustion score, and a positive association with the change in depression. Although these associations are statistically significant, they only explain a small fraction of the variance in cortisol after awakening between and within persons. This implies that changes at symptom level are hardly related to changes in cortisol functioning, therefore the clinical implications of this finding are limited.

Adaptation, Physiological↗