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PubMed1998

An illustration of item homogeneity scaling and multilevel analysis techniques in the evaluation of drug prevention programs.

Many reports of successful school-based intervention programs can be criticized for their choice of a unit of analysis and for the neglect of measurement errors. This article is an illustration of how different conclusions can be reached from different choices of units of analyses and/or of different treatment of the data. This is done by a reanalysis of a well-reported data set. The data is thoroughly taken apart, using different statistical techniques. The result of the analyses shows that earlier reported effects of a normative school-based drug prevention program were not found. The subsequent search for moderator effects of the same program, such as a lowering effect on the relationship between the pre- and posttest or on the relationship between respondents' use and the use of their friends, was not successful either. It is concluded that the null hypothesis of zero effects should be retained. More successful was a search for individual characteristics that show significant relationships with respondents' alcohol use. Among them was the abuse of alcohol by adults in respondents' direct social environment and the use of friends.

Adolescent↗
PubMedDate not supplied

Evaluation of an intergenerational program for pregnant and parenting adolescents.

PROBLEM: Poor life outcomes for teenage mothers SUBJECTS: Young mothers (N = 65) several years after the birth of their first child. Half had mothers (called grandmothers) who attended the Teenage Mothers-Grandmothers program. METHODS: A long-term evaluation study of the effects of the Teenage Mothers-Grandmothers Program on outcomes for the teens. Instruments used: demographic questionnaire, the Rosenberg Self-Esteem Scale, the Arizona Social Support Inventory Schedule, and an open-ended questionnaire. FINDINGS: Teens whose mothers participated in the program were significantly less likely to drop out of school and had significantly better self-esteem. CONCLUSIONS & IMPLICATIONS FOR NURSING: Including the mothers of pregnant and parenting adolescents in programs can be beneficial.

Adolescent↗
PubMed2006

The intrinsic mechanisms underlying the maturation of programming sequential spikes at cerebellar Purkinje cells.

Cerebellum is involved in the motion coordination and working memory, to which the programming of sequential spikes at Purkinje cells is essential. It is not clear about the intrinsic mechanisms underlying spike capacity and timing precision as well as their postnatal maturation. We investigated the programming and intrinsic property of sequential spikes at Purkinje neurons during postnatal development by whole-cell recording in cerebellar slices. Cerebellar Purkinje neurons demonstrate the increasing of spike capacity and timing precision, as well as the lowering of refractory periods and threshold potentials during the postnatal maturation. In addition, the correlation between spike parameters and intrinsic properties converts to be more linear. This postnatal plasticity of neuronal intrinsic properties improves the timing precision and capacity of spike programming at cerebellar Purkinje neurons.

Action Potentials↗
PubMed2004

How important are client characteristics to understanding treatment process in the therapeutic community?

Prior research has demonstrated that therapeutic communities (TCs) are effective at improving posttreatment outcomes for substance abusers. However, little is known about the in-treatment experience for clients with different backgrounds, experiences, and needs. The aim of this study is to examine the in-treatment experience for different clients by exploring the relationships between treatment process and client characteristics. A comprehensive measure of treatment process, operationalized as Community Environment and Personal Change and Development and change was administered to 447 adults and 148 adolescents receiving treatment at community-based TC programs in New York, California, and Texas. Data on demographic characteristics, substance use and treatment history, and client risk factors were extracted from intake interviews and analyzed separately for adolescent and adult residents. Multivariate general linear models were used to examine the effect of client variables on treatment process, after controlling for treatment duration and program effects. Within adult programs, clients who were 25 years or older, female, and had a prior drug treatment experience had higher Community Environment scores. Adolescents with one or more arrests within the past 2 years had lower scores on both process dimensions of Community Environment and Personal Development and Change. Our results indicate the need to understand why adult clients who are younger, male, and have no prior treatment history and adolescent clients with recent arrests reported lower ratings of treatment process. Future research should also examine the role of modifiable mediators so that appropriate strategies to enhance therapeutic engagement may be developed as necessary.

Adolescent↗
PubMed1990

Androgyny: a function of degree?

Related to the issue of sexism is the concept of psychological androgyny, or the lack of tendency toward masculine or feminine traits. Studies have examined psychological androgyny through administration of the BEM Sex-Role Inventory and the Guilford-Zimmerman Temperament Survey. Whereas one researcher concluded that dental hygiene students are stereotypically feminine, another researcher reported the tendency toward traditionally masculine traits. Both researchers utilized samples consisting solely of baccalaureate students. This paper presents the issue of psychological androgyny, the impact that sex-typing has on the profession of dental hygiene, and the results of a study examining androgyny among dental hygiene students. Three hundred twenty-one first- and second-year dental hygiene students representing four geographic regions within the United States were sampled. The 60-item BEM Sex-Role Inventory was administered to determine the extent of masculinity, femininity, and androgyny within this sample. Comparisons were made by degree program, class status, and geographic location. The authors tested the hypothesis that baccalaureate degree-seeking dental hygiene students were more androgynous than associate degree-seeking dental hygiene students. Data were analyzed by a general linear model for unbalanced designs and chi-square to determine significance. Results indicated that students in all dental hygiene programs are most frequently sex-typed as feminine, with androgyny as the second most frequently sex-typed characteristic. There was a significant difference in psychological androgyny when comparing students by degree program. A greater number of baccalaureate degree-seeking students reflected an androgynous sex-typing.

Analysis of Variance↗
PubMed2002

Evaluation of a dual hemoglobin A(2)/A(1c) quantitation kit on the bio-rad variant II automated hemoglobin analyzer.

CONTEXT: Quantitation of hemoglobin (Hb) A(1c) and investigation of hemoglobinopathy on the Bio-Rad Variant analyzers require a switch between 2 separate kits that is time consuming and causes errors. OBJECTIVE: Evaluation of a new Variant II HbA(2)/HbA(1c) Dual kit capable of both Hb A(1c) quantitation and hemoglobinopathy investigation on a single kit. DESIGN: We evaluated Hb A(1c), Hb A(2), and Hb F quantitation for precision, linearity, and correlation with current methodology. We also evaluated detection of Hb variants and correlation of Hb Barts quantitation. SETTING: Hamilton Regional Laboratory Medicine Program, Provincial Hemoglobinopathy Laboratory, St Joseph's Healthcare Site, Hamilton, Ontario. PATIENTS: Patient blood samples submitted for Hb A(1c) quantitation or hemoglobinopathy investigation. MAIN OUTCOME MEASURES: Precision, linearity, linear regression, and reference interval validation. RESULTS: We provide tables and figures illustrating precision, linearity, linear regression, and quantitation of Hb variants. We validated reference intervals for Hb A(1c), Hb A(2), and Hb F. CONCLUSIONS: The dual kit provides precise Hb A(1c), Hb A(2), and Hb F quantitation. The results show good linearity and correlate well with the results of current methods. We detected all clinically important Hb variants and a wide variety of rare variants. The dual kit has several advantages: it eliminates the need for extensive kit switch over; improves utility for newborn screening because of its quantification of Hb Barts; permits quantification of Hb A(1c) using the beta-Thal method; and eliminates the need for separate Hb A(2) reference intervals for patients with Hb S because of its accurate quantitation of Hb A(2) in the presence of Hb S.

Fetal Hemoglobin↗
PubMed1985

Financial impact of home health care on the hospital.

A method for analyzing the financial impact of new home health-care (HHC) programs on the hospital is presented. Clinical service objectives and long-term goals for new programs must match patient needs with institutional opportunities and constraints. Planning and evaluating new HHC programs require an accurate analysis of the financial impact of the proposed program on the hospital. A method for financial program analysis is presented through three different hypothetical scenarios based on realistic situations of hospitals considering HHC alternatives. Marginal analysis is presented as a microeconomic tool, and the calculation of marginal cost from a linear total cost function is described. Pro forma spread sheets of revenue and expense are used to assess three different HHC program alternatives--an independent HHC agency, a hospital-based agency, and a joint venture between a vendor and a hospital. Net present-value calculations are explained and applied to one case. It is important to use realistic assumptions in estimating the financial performance of HHC programs.

Cost-Benefit Analysis↗
PubMed1987

Efficient pharmacokinetic modeling of complex clinical dosing regimens: the universal elementary dosing regimen and computer algorithm EDFAST.

Dosing regimens used in clinical practice are often complex, involving several different routes of administration, dose sizes, dosing rates, and dosing intervals and durations. A novel universal elementary dosing regimen (uedr), that allows general pharmacokinetic modeling of these clinical regimens, is presented and developed mathematically. The uedr concept is computationally efficient, mathematically exact, and logically simple, and can replace the disparate standard concepts and equations of elementary infusion, "bolus" injection, multiple injection, oral dosing, zero-order-release dosing, etc. An optimized computer algorithm (EDFAST) based on the uedr approach, that readily permits the creation of a single fast and versatile microcomputer program for the analysis of all complex dosing regimens in any set of linear compartmental models, is presented. This is of particular relevance to three areas of application in clinical pharmacokinetics: compartmental drug concentration or amount versus time course prediction (simulation) with known model parameter values; parameter estimation (curve-fitting) from measured concentration versus time data; and individualized complex dosing regimen calculation (optimization) for target sets of concentration-time points. Application examples that show the versatility of the uedr approach are presented in detail.

Algorithms↗
PubMed1991

Linear arrays of homogeneous mast cells in the dura mater of the rat.

Using fluorescence histochemistry, 5-HT, histamine and heparin were colocalized in a large population of cells in the dura mater thereby identifying them as mast cells. In addition, because these cells were highly sensitive to compound 48/80 and were densely packed with granules of a consistent density, they were identified specifically as 'connective tissue' mast cells. Other types of mast cells, i.e. 'mucosal' or 'neurolipomastocytes', were not present in the rat dura mater. 5-HT immunohistochemistry was the best technique for demonstrating that there were populations of mast cells, one associated with each of the two layers of dura. Although shaped differently the type of mast cell in each layer was the same. It was observed that mast cell shape is dependent on the contiguity, density and orientation of its surrounding elements, not its type. In general, mast cells in the outer layer were aligned parallel to the middle meningeal artery and those in the inner layer were parallel to trigeminal nerve branches that coursed obliquely across the middle meningeal artery. Examination of cross-sections of dura revealed that most mast cells also were aligned at the interface between the two dural layers. The linear orientation of mast cells in two planes of each layer suggests a programmed lamellar seeding of these cells during development of the dura. This study also demonstrated that the majority of dural mast cells were more closely related to other connective tissue elements than to blood vessels and nerves. These results (1) are compatible with the suggestion that dural mast cells play a non-obligatory role in the neuroinflammatory response, (2) leave open to question the role of the dural mast cell in headache or the regulation of blood flow, and (3) support evidence that dural mast cells play an important role in connective tissue related functions, e.g. development, inflammatory response to injury and wound repair.

Animals↗
PubMed2003

Sampling strategies exploiting multi-pumping flow systems.

In this work new strategies were exploited to implement multi-pumping flow systems relying on the utilisation of multiple devices that act simultaneously as sample-insertion, reagent-introduction, and solution-propelling units. The solenoid micro-pumps that were initially used as the only active elements of multi-pumping systems, and which were able to produce pulses of 3 to 25 microL, were replaced by syringe pumps with the aim of producing pulses between 1 and 4 microL. The performance of the developed flow system was assessed by using distinct sample-insertion strategies like single sample volume, merging zones, and binary sampling in the spectrophotometric determination of isoniazid in pharmaceutical formulations upon reaction with 1,2-naphthoquinone-4-sulfonate, in alkaline medium. The results obtained showed that enhanced sample/reagent mixing could be obtained with binary sampling and by using a 1 microL per step pump, even in limited dispersion conditions. Moreover, syringe pumps produce very reproducible flowing streams and are easily manipulated and controlled by a computer program, which is greatly simplified since they are the only active manifold component. Linear calibration plots up to 18.0 microg mL(-1), with a relative standard deviation of less than 1.48% (n=10) and a throughput of about 20 samples per hour, were obtained.

Antitubercular Agents↗
PubMed1994

Bayesian-logit model for risk assessment in coronary artery bypass grafting.

Predictive models for the assessment of operative risk using patient risk factors have gained popularity in the medical community as an important tool for the adjustment of surgical outcome. The Bayes' theorem model is among the various models used to predict mortality among patients undergoing coronary artery bypass grafting procedures. Comparative studies of the various classic statistical techniques, such as logistic regression, cluster of variables followed by a logistic regression, a subjectively created sickness score, classification trees model, and the Bayes' theorem model, have shown that the Bayes' model is among those with the highest predictive power. In this study, the Bayes' theorem model is reformulated as a logistic equation and extended to include qualitative and quantitative risk factors. We show that the resulting model, the Bayesian-logit model, is a mixture of logistic regression and linear discriminant analysis. This new model can be created easily without complex computer programs. Using 12,712 patients undergoing coronary artery bypass grafting procedures at the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Study between April 1987 and March 1990, the predictive power of the Bayesian-logit model is compared with the Bayes' theorem model, logistic regression, and discriminant analysis. The ability of the Bayesian-logit model to discriminate between operative deaths and operative survivors is comparable with that of logistic regression and discriminant analysis.

Age Factors↗
PubMed2006

Evaluation of the VITROS chemistry products dHDL slides for direct measurement of high density lipoprotein cholesterol.

BACKGROUND: We evaluated the new VITROS direct high density lipoprotein cholesterol (dHDL) slide assay, based on the precipitation of apolipoprotein B-containing lipoproteins by phosphotungstic acid/magnesium chloride (PTA/MgCl2). METHODS: We determined linearity, within-run and between-run imprecision for the VITROS dHDL slide assay, and compared it to the RANDOX two-step PTA/MgCl2 method for 300 fresh sera. Moreover, triglyceride and cholesterol interference were tested. RESULTS: The VITROS dHDL slide assay was linear from 0 to 3.13 mmol/l. Within-run and between-run imprecision were 1.6%, 1.8%, 3.3% and 3.2% for target values at 1.00 and 1.40 mmol/l, respectively. For 300 fresh serum samples, the linear regression equation between the VITROS dHDL slide assay (y) and the RANDOX PTA/MgCl2 2 method (x) was: y (mmol/l)=0.934 x+0.043 (CI=0.916-0.952 for slope and 0.017-0.069 for intercept) . The bias of the VITROS assay compared to the RANDOX PTA/MgCl2 method was less than 5% for HDL cholesterol concentrations used for medical decision (1.04 and 1.50 mmol/l). Total error remained below 13% for triglyceride and LDL cholesterol concentrations below 6.6 mmol/l. CONCLUSION: The VITROS dHDL slide assay is rapid, linear over a broad range of concentrations, and satisfies the National Cholesterol Education Program goals for precision and accuracy.

Cholesterol, HDL↗
PubMed2005

Experimentally verified model of mechanomyograms recorded during single motor unit contractions.

The aim of the paper is to create a model which enables to observe the mechanomyographic (MMG) wave generated during single motor unit contractions in a muscle, while the muscle is immersed in paraffin oil. The muscle model is described as a rheological membrane. Both the muscle and the medium models have been built by using Stiff-Finite-Element-Method (SFEM), which allows one to simulate the muscle surface displacement and the acoustic propagation of this effect in the oil. Such a modelling enables one to determine the impact of the rheological properties of the liquid environment on the shape of the MMG wave. In order to verify the model, the MMG signals and the contraction forces have been recorded in vivo from the medial gastrocnemius muscle of a rat. In these experiments single motor units were stimulated with various stimulation frequencies. A piezotransducer, immersed in paraffin oil, has been used to record the MMG signal recording. The signals recorded during individual twitches of the motor units have been used to estimate the parameters of the model. Subsequently, the model has been experimentally verified. The signals recorded in experiments during unfused and fused tetani have been compared with the simulated model responses in the analogous stimulation program. It has been observed that the MMG signals obtained with the proposed linear model have been consistent with the results of in vivo experiments.

Animals↗
PubMedDate not supplied

Detecting changes in serial myocardial perfusion SPECT: a simulation study.

BACKGROUND: New algorithms were evaluated for their efficacy in detecting and quantifying serial changes in myocardial perfusion from single photon emission computed tomography (SPECT). METHODS AND RESULTS: We generated 72 simulations with various left ventricular positions, sizes, count rates, and perfusion defect severities using the nonuniform rational B-splines (NURBs)-based CArdiac Torso (NCAT) phantom. Images were automatically aligned by use of both full linear and rigid transformations and quantified for perfusion by use of the CEqual program. Changes within a given perfusion defect were compared by use of a Student t test before and after registration. Registration approaches were compared by use of receiver operating characteristic analysis. Changes of 5% were not detected well in single patients with or without alignment. Changes of 10% and 15% could be detected with false-positive rates of 15% and 10%, respectively, in single studies if alignment was performed before perfusion analysis. Alignment also reduced the number of studies necessary to demonstrate a significant perfusion change (P < .05) in groups of patients by about half. CONCLUSION: Comparison of mean uptake by t values in SPECT perfusion defects can be used to detect 10% and greater differences in serial perfusion studies of single patients. Image alignment is necessary to optimize automatic detection of perfusion changes in both single patients and groups of patients.

Computer Simulation↗
PubMed2006

Maternal social and pyschological conditions and physical growth in low-income children in Piauí, Northeast Brazil.

Prevalence of child undernutrition remains high in many developing countries. In settings with scarce resources, modifiable maternal social conditions may influence feeding and parenting practices, in turn affecting child growth. This study aims to quantify the association between maternal social support and depression to children's physical growth outcomes in Teresina, Piauí, northeast Brazil. Interviews were conducted with a random sample of 595 mothers of children 6-24 months old in four low-income sections of Teresina, Piauí. We collected data on sociodemographic factors, mothers' social support, mothers' depressive symptomatology, and child's weight and recumbent length. Weight-for-height z-scores (WHZ), height-for-age z-scores (HAZ) and weight-for-age z-scores (WAZ) were calculated using the National Center for Chronic Disease Prevention and Health Promotion Center SAS program based on the 2000 Centers for Disease Control reference growth curves. Multivariable linear regression was used to model the association between maternal social support and depression to child growth, adjusting for biological and socio-demographic variables. Interviewer and neighborhood variation was accounted for through the inclusion of random effects. In adjusted models, material support, measured by number of friends or family members available to mothers when needing food or milk, was related to 0.3 higher average WHZ and 0.2 higher average WAZ in their children. Maternal positive social interaction, which reflects engagement in leisure-time activities with others, was associated with 0.3 higher average WHZ. Mothers' affectionate support was related to 0.2 higher average children's WHZ and WAZ, whereas social support for resolving a conflict was associated with 0.2 lower average HAZ. Maternal depression was not associated with child growth. It is concluded that inadequate growth in children may be sensitive to maternal social support.

Brazil↗
PubMed2002

On the solution of mixed-integer nonlinear programming models for computer aided molecular design.

This paper addresses the efficient solution of computer aided molecular design (CAMD) problems, which have been posed as mixed-integer nonlinear programming models. The models of interest are those in which the number of linear constraints far exceeds the number of nonlinear constraints, and with most variables participating in the nonconvex terms. As a result global optimization methods are needed. A branch-and-bound algorithm (BB) is proposed that is specifically tailored to solving such problems. In a conventional BB algorithm, branching is performed on all the search variables that appear in the nonlinear terms. This translates to a large number of node traversals. To overcome this problem, we have proposed a new strategy for branching on a set of linear branchingfunctions, which depend linearly on the search variables. This leads to a significant reduction in the dimensionality of the search space. The construction of linear underestimators for a class of functions is also presented. The CAMD problem that is considered is the design of optimal solvents to be used as cleaning agents in lithographic printing.

Journal Article↗
PubMed2003

The influence of distance on utilization of outpatient mental health aftercare following inpatient substance abuse treatment.

This study examined whether substance abuse patients who live farther from their source of outpatient mental health care were less likely to obtain aftercare following an inpatient treatment episode. For those patients who did receive aftercare, distance was evaluated as a predictor of the volume of care received. A national sample of 33,952 veterans discharged from Department of Veterans Affairs (VA) inpatient substance abuse treatment programs was analyzed using a two-part choice model utilizing logistic and linear regression. Patients living farther from their source of outpatient mental health care were less likely to obtain aftercare following inpatient substance abuse treatment. Patients who traveled 10 miles or less were 2.6 times more likely to obtain aftercare than those who traveled more than 50 miles. Only 40% of patients who lived more than 25 miles from the nearest aftercare facility obtained any aftercare services. Patients who received aftercare services had fewer visits if they lived farther from their source of aftercare. Lack of geographic access (distance) is a barrier to outpatient mental health care following inpatient substance abuse treatment, and influences the volume of care received once the decision to obtain aftercare is made. Aftercare services must be geographically accessible to ensure satisfactory utilization.

Adult↗
PubMed1999

Independent and incremental value of coronary artery calcium for predicting the extent of angiographic coronary artery disease: comparison with cardiac risk factors and radionuclide perfusion imaging.

OBJECTIVES: The study was done to test the ability to predict the extent of angiographically determined coronary artery disease (CAD) by quantification of coronary calcium using electron-beam computed tomography (EBCT) and to compare it with more conventional parameters for delineating the angiographic extent of CAD, that is, cardiovascular risk factors and radionuclide single-photon emission computed tomography (SPECT). BACKGROUND: The angiographic extent of CAD is a powerful predictor of subsequent events. Use of EBCT may be able to define it by virtue of its ability to determine plaque burden. METHODS: We examined 308 patients presenting with suspected but not previously known CAD who underwent selective coronary angiography. As measures of the angiographic extent of CAD, coronary artery greater even 20 (CAGE > or =20) and CAGE > or =50 scores represented the total number of coronary segments with > or =20% or > or =50% stenoses, respectively. The EBCT-derived total calcium scores were obtained in 291 patients, risk factors as defined by the National Cholesterol Education Program in 239 patients, and SPECT scans in 136 patients. RESULTS: Using multiple linear regression analysis, total calcium scores were better independent predictors of both CAGE > or =20 and CAGE > or =50 scores than either a SPECT-derived radionuclide perfusion score or the risk factors age, male gender and ratio of total/high-density lipoprotein (HDL) cholesterol. The association between EBCT and angiographic scores remained highly significant after excluding the influence of all interrelated risk factors and SPECT variables (r = 0.65; p < 0.001 for CAGE > or =20 scores, r = 0.50; p < 0.001 for CAGE > or =50 scores). CONCLUSIONS: Coronary calcium predicts the angiographic extent of CAD in symptomatic patients and provides independent and incremental information to the more conventional clinical parameters derived from SPECT or risk assessment.

Aged↗