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PubMed2002

Nurses' decision-making in collecting information for the assessment of patients' nursing problems.

1. The paper addresses two questions: Firstly, what kind of information do nurses acquire from cancer patients for purposes of judging their patients' problems and preparing a care plan? Secondly, how systematically do nurses proceed in the decision-making process from the formulation of initial assumptions about the patient's situation to the final definition of problems? 2. The instrument used for data collection was a computer-simulated case description compiled by a team of four nursing researchers and one medical researcher. The case description was based on a real patient history. 3. The sample consisted of 107 Registered Nurses on four oncology, two internal medicine and five surgical wards of two central university hospitals in Finland. Data were collected in autumn 1998 and spring 1999 using a laptop computer and a tape recorder. 4. The four most important problems identified by nurses at baseline were pain (85%), pain medication (59%), family situation (66%) and spread of cancer (49%). Presented with a list of 23 options, they obtained additional information on average on 13 areas. Almost one-third collected information from 16 to 22 areas. On average nurses identified 12 of the 28 nursing problems specified. A statistically significant association was observed between information acquisition and problem definition in seven different variables. These had to do with pain, general condition and prognosis. 5. Nurses adequately prioritized their patients' problems and systematically collected data on those problems. On the other hand they also identified a number of problems that were not relevant to the situation.

Clinical Competence↗

PubMed1994

Comparisons between Hologic, Lunar and Norland dual-energy X-ray absorptiometers and other techniques used for whole-body soft tissue measurements.

OBJECTIVES: Assessment of the precision and accuracy of dual-energy X-ray absorptiometers (DXA) from three manufacturers, used for measuring soft-tissue composition, and comparability with each other and other techniques. DESIGN: Measurements of an anthropomorphic model of variable composition and thickness. 11 volunteers measured with each instrument and by underwater weighing (UWW) and three brands of bioelectric impedance analysis (BIA) apparatus. RESULTS: New software, introduced by each manufacturer during the course of the investigation, led to changes in measured fat proportion. The precision of determination of fat proportion by DXA in the (small) model was 3-4% (coefficient of variation), with little difference between brands. In vivo precision was 2-3%. In the model, measurements of % fat differed from the nominal values, but variation with thickness was small. There were significant mean differences of total fat proportion in the volunteers between pairs of DXA instruments of 2.6-6.3% fat. The SDs of the differences were 1.8-2.9% fat. Regional differences were greater, with trunk % fat being particularly underestimated by Hologic relative to Lunar and Norland. Compared with UWW, mean % fat was the same for Hologic, but higher for Lunar and Norland. SDs of 4% demonstrated inadequate agreement. The differences varied with proportion of bone in lean tissue, questioning the assumption of constant density of lean tissue in UWW. There were no mean differences of % fat between the BIA instruments and DXA and UWW, but SDs of 3-6% suggest that BIA using these instruments does not offer an acceptable accuracy in estimating fat proportion. CONCLUSIONS: UWW has limitations as a reference method. DXA is a useful technique, but its limitations, particularly regarding assumptions about fat distribution, must be borne in mind. The differences of fat proportion recorded by the three DXA instruments are such as to preclude interchangeability in measurements of individual subjects or in clinical trials.

Absorptiometry, Photon↗

PubMed1988

Psychological gender, hand preferences, and sex differences in book-carrying styles.

Individuals with stronger sex-role identities may be expected to show greater conformity to sex-typed behaviors. Proceeding from this assumption, the sex-role status and sex of students using different styles of carrying books were compared. This study also examined whether over-all hand preference or age were related to carrying styles or sex-role status. Subjects completed a questionnaire comprised of the 24-item Personal Attributes Questionnaire of Spence and Helmreich, a 6-item scale of hand preference and a self-rating of sex-role identity. Afterwards, each subject's carrying style was covertly observed and recorded. Most subjects carried their materials in a sex-typical way or in book bags (for which no sex-typed carrying styles were discovered). As in previous studies, men in this study scored higher than women on masculinity and androgyny and lower on femininity. Hand preference was not related to sex-role status. Carrying style was not significantly correlated with any of the predictor variables for men, perhaps because almost no variance in carrying style was observed among them. Women who used masculine carrying styles tended to be older, have greater instrumentality, and a more masculine identity.

Adolescent↗

PubMedDate not supplied

[Comparison of subjective and objective quality of life in a group of schizophrenic patients].

AIM: The aim of this study is a comparison of subjective and objective quality of life in schizophrenic patients. METHODS: The research was carried out on 120 in- and out-patients (from 19 to 65 years) who fulfilled ICD-10 and DSM-IV criteria for schizophrenia. The quality of life was assessed by means of two instruments: Quality of Life Scale (QLS, Heinrichs et al. 1984), Self-Report Quality of Life Measure for People with Schizophrenia (SQLS, Wilkinson et al. 2000). The basic statistical methods used were: correlation analysis between measurable variables with Pearson's index (P), t-Student test, analysis of variance, factor analysis. RESULTS: In the investigated group there is no correlation between subjective and objective quality of life. Sex does not influence a correlation between these variables. Subjective and objective quality of life correlate with each other only in out-patients' group (P = -0.386). The factor analysis of SQLS distinguished 7 factors: mood; everyday activities, side effects connected with movement; side effects- others; support; interpersonal contacts; others; this division differs completely from a division on subscales. The factor analysis of QLS distinguished 3 factors: intrapsychic functioning; social functioning; functioning in roles; this division is similar to a division on subscales. CONCLUSIONS: It seems that in the schizophrenic patients' group using subjective and objective ways to assess the quality of life determines a difference of the obtained results. Only the subjective measurement fulfills the assumption of quality of life definition, that is why the usefulness of QLS in assessing quality of life is rather restricted.

Activities of Daily Living↗

PubMed1992

Quantification of motor deficit in Parkinson's disease with a motor performance test series.

It was the purpose of the present study to quantify the expected motor deficit in parkinsonian patients with the computer assisted Motor Performance Test Series (MPS), version 05.87 by Schuhfried (1987) and to examine which of the motor test variables found correlate at a significance level of p less than 0.01 with items of "motor examination" recorded at neurological examination and "activities of daily living" of the Unified Parkinson's Disease Rating Scale (UPDRS), version 3.0. 38 patients with idiopathic Parkinson's disease (PD) stages I-IV according to Hoehn and Yahr, aged 41 to 73 years were studied. The study design, i.e. initial rating by the physician followed immediately by testing of motor function with MPS was strictly adhered to in each patient. Physician's rating of rigor and the scores of the semiquantitative tests (finger taps, hand movements and alternating movements) as expression of hypokinesia and the "activities of daily living" correlated with the 3 factors of the Motor Performance Test Series at a highly significant level independent of disease stage. Tremor is only partly and never significantly reflected in the motor data measured. Stages I-II and II-IV (Hoehn and Yahr) differ significantly in the representative data of the Motor Performance Test Series. The results of the study support the assumption that MPS is a valid instrument for quantitative measurement of the motor deficit in parkinsonian patients, but that only some subtests are "pathognomonic".

Activities of Daily Living↗

PubMed2000

Test-retest reliability study of a new improved Leg-O-meter, the Leg-O-meter II, in patients suffering from venous insufficiency of the lower limbs.

The objective of this study was to evaluate the interobserver and test-retest reliability of the new improved Leg-O-Meter, the Leg-O-Meter II, an instrument designed to measure leg circumference. The new Leg-O-Meter consists of a tape measure fixed to a stand attached to a small board on which the patient is in standing position. Only the left limb is measured. For this study the tape measure of the Leg-O-Meter was fixed at 13 cm from the board. Subjects were recruited from patients consulting the phlebology clinic of Hopital St-Michel, Paris, France. Thirty-nine patients were asked to participate in the test phase and a subsample of 20 patients were asked to participate in addition to a retest phase 10 minutes after their first measurement. Patients were asked to enter a closed room where four independent and blinded observers consecutively took measurements of their left calf with the Leg-O-Meter II. Twenty patients were also asked to come back 10 minutes later for a second round of measurements. While waiting, patients were seated. Variables collected included leg circumference, presence of edema, clinical presentation, and venous insufficiency treatment history. The order of the observers was randomized between patients. Under the assumption of a two-way random effects model, an intraclass correlation coefficient (ICC) was used to determine the reliability of a measure with the Leg-O-Meter II as well as the test-retest reliability. The interobserver and test-retest reliabilities of the Leg-O-Meter II were 98.28% [96.90%, 100.00%] CI95% and 95.90% [92.00%, 100.00%] CI95%, respectively. The Leg-O-Meter II has higher interobserver reliability and is easier to manipulate than the previous version. In addition, it has substantive test-retest reliability.

Anthropometry↗

PubMed1988

Slow brain potentials, imagery and hemispheric differences.

On the basis of Lang's (1979) theory of emotional imagery three experiments were conducted to investigate the relationship between slow cortical potentials (SP) and emotional imagery. According to the assumptions of Lang's theory and our model (Rockstroh et al., 1982) of SP-function imagery ability should be related to a person's capacity to generate and suppress preparatory activity in cortical networks "on demand." In order to test this hypothesis subjects in Experiment I were trained to regulate right- versus left-hemispheric SP-differentiation within an instrumental learning paradigm. Thirty-four subjects were reinforced for achieving maximal SP-differences between electrode locations C3-C4 over a 6 s interval across 120 trials. Success in the SP-regulation task correlated significantly (r = .37) with the capacity for vivid imagery as measured with the Questionnaire for Mental Imagery (QMI). In Experiment II instructions to imagine right- versus left-hand movements were introduced successively over 5 sessions of SP-self-regulation. Imagery clearly modified right- versus left-hand EMG-differentiation but had no influence on cortical SP-differentiation. Experiment III tested the influence of already achieved SP-regulation at the vertex on the perceived vividness of emotional images introduced after the SP-biofeedback training. Again, clear effects of imagery content on autonomic variables (HR, SCR) were found. However, SP-amplitude and SP-polarity had no effect on perceived vividness, arousal or emotional content. It may be concluded from the results of Experiment II and III that SPs either are not the crucial parameter to represent the cortical efferent outflow component of imagery, or that the dual task of SP-self-regulation and imagery prevented covariations to show up. Experiment I, on the other hand, points toward a positive relation of imagery-ability as a trait-variable and brain-self-regulation abilities.

Brain↗

PubMed1987

Statistical methods for growth allometric studies.

Simple least square regression analysis, major axis regression, and reduced major axis regression have been advocated for straight line fitting to the logarithmically transformed data pairs in bivariate allometric studies. As all these techniques are based on rigid a priori assumptions on the error structure, their application may lead to considerable biases in slope estimation if these requirements are not met. A different mathematical model, the linear functional relationship, allows to remove the bias by estimating the error structure from grouped empirical data. The model is applicable to interspecific and cross-sectional growth allometric studies where natural grouping criteria are available (species, age). The technique is illustrated by growth allometry of myocardial cells and capillaries in the late postnatal period (after weaning) in 33 normal male Wistar rats (group 1: 5 weeks, group 2: 7 weeks, group 3: 13 weeks, group 4: 52 weeks). In left ventricular myocardium fixed by vascular perfusion, length and volume densities of myocardial cells and capillaries were estimated by stereological techniques at the light and electron microscopic level. Total capillary length and total myocardial cell volume were scaled to total myocardial cell length. A comparison of the scaling methods showed an underestimation of the slope and its confidence interval by all regression techniques, which would have led to the erroneous conclusion that the myocardial cell does not remain geometrically similar throughout the normal growth process. Linear functional relationship and the technique of instrumental variables led to nearly identical results and were both compatible with geometric similarity of the myocardial cell during growth. Positive allometry of total capillary length to total myocardial cell length (b = 1.674) demonstrates continuous neoformation of capillaries. The intensity of capillary proliferative activity during growth was intermediate between the reactions observed in myocardial hypertrophy due to pressure overload and that due to physical training. This agrees with the fact that both systemic arterial pressure and cardiac output increase during maturation. The study is designed as a worked example which should enable the practicing researcher to treat data from cross-sectional growth allometric studies with a simple and unbiased statistical method.

Animals↗

PubMed1995

Three-dimensional echocardiography improves noninvasive assessment of left ventricular volume and performance.

To calculate left ventricular (LV) volume by two-dimensional echocardiography (2DE), assumptions must be made about ventricular symmetry and geometry. Three-dimensional echocardiography (3DE) can quantitate LV volume without these limitations, yet its incremental value over 2DE is unknown. The purpose of this study was to compare the accuracy of LV volume determination by 3DE to standard 2DE methods. To compare the accuracy of 3DE with standard 2DE algorithms for quantitating LV volume, 28 excised canine ventricles of known volume and varying shapes (15 symmetric and 13 aneurysmal) and 10 instrumented dogs prepared so that instantaneous ventricular volume could be measured were examined by 2DE (bullet and biplane Simpson's formulas) and again by 3DE. In both excised and beating hearts, 3DE was more accurate in quantitating volume than either 2DE method (excised: error = 0.6 +/- 3.2, 2.5 +/- 10.7, and 4.0 +/- 8.5 ml by 3D, bullet, and Simpson's, respectively; beating: error = -0.5 +/- 3.5, -0.3 +/- 9.6, and -7.6 +/- 8.0 ml by 3DE, bullet, and Simpson's, respectively). This difference in accuracy between 3DE and 2DE methods was especially apparent in asymmetric ventricles distorted by ischemia or right ventricular volume overload. Stroke volume and ejection fraction calculated by 3DE also demonstrated better agreement with actual values than the bullet or Simpson methods with less variability (ejection fraction: error = -2.0% +/- 5.1%, 7.7% +/- 8.5%, and 6.8% +/- 12.3% by 3DE, bullet, and Simpson's, respectively). In both in vitro and in vivo settings, 3DE provides improved accuracy for LV volume and performance than current 2DE algorithms.

Animals↗

PubMed1985

Multivariate evaluation of health attitudes and behaviors: development and validation of a method for health promotion research.

Many self-reported measures of health status, attitudes, and knowledge used by clinicians and researchers suffer from a variety of shortcomings, including limited empirical justification, excessive complexity, assessments of nonmodifiable historic or hereditary factors, and limited utility for public health program planning. The Health Attitudes and Behavior Scale is an instrument designed to overcome many of these shortcomings and direct public health professionals toward more efficacious interventions. One hundred sixty-four subjects responded to true-false and Likert scale items related to health beliefs, attitudes, and behavioral practices. A principal component analysis of the Likert items yielded six components, tentatively labeled (a) Lack of Social Support, (b) Hurdles to Health, (c) Health Attitudes/Weight Concerns, (d) Positive Environment, (e) Disease Concerns, and (f) Time and Work Pressure. Analyses of these scales using coefficient alpha indicated adequate internal consistency for each of them. These scales were then related to demographic variables of age, educational level, sex, and marital status. Next, these scales were correlated with individual true-false items reflecting self-reported behavioral practices or health histories. A component analysis of the true-false items yielded four principal components labeled (a) Organizational Health Concerns, (b) Smoking and Exercise Concerns, (c) Coronary and Weight Concerns, and (d) Blood Pressure and Risk Factor Programs. Finally, a cluster analysis yielded six typical profiles reflecting different levels of the original six components. Of interest is the fact that the Lack of Social Support and Time and Work Pressure scales had a very limited integration into the overall patterns. The assumption that organizational and environmental factors can have an important impact on health was supported. The need for further research in this area is also discussed.

Adolescent↗

PubMed2000

Respondent-generated quality of life measures: useful tools for nursing or more fool's gold?

Within health services research the quest for better ways of measuring quality of life as an outcome variable continues apace. Recent developments in this area have seen increasing attempts to incorporate individually generated content and values into quality of life measures while retaining valid psychometric measurement properties. Following a brief overview of current conceptual approaches to quality of life measurement, this paper reviews the development of two leading Respondent-generated instruments: the Schedule for the Evaluation of Individual Quality of Life (SEIQoL) and the Patient Generated Index (PGI). The relative strengths and weaknesses of these tools and their potential applications for nursing and nursing research are appraised. These measures both address and manifest a number of fundamental conceptual and methodological problems, and represent an innovative attempt to square the quantitative--qualitative circle. As such they offer challenging opportunities for nursing at a number of levels. Their elicitation and quantification of individual components of quality of life offer opportunities for nurses to plan care and goal set with patients. As yet, however, the validity, reliability, responsiveness and practicality of these instruments as outcome measures are debatable and require further testing. Nurse researchers could contribute to this process by using Respondent-generated measures as an adjunct to existing, established tools in outcome studies. Moreover, nursing is well placed to investigate and debate the validity of the conceptual assumptions underpinning these new instruments.

Attitude to Health↗

PubMed1992

An empirical evaluation of the Global Deterioration Scale for staging Alzheimer's disease.

OBJECTIVE: Although the Global Deterioration Scale has been widely used since its publication in 1982, its stages are based on implicit assumptions about the linearity, temporality, and interdependence of cognitive, functional, and behavioral impairment in Alzheimer's disease. The authors evaluated the validity of these assumptions and tested the hypothesis that psychopathology and functional impairment would occur in earlier stages than the Global Deterioration Scale predicts. METHOD: The analyses were based on data on 324 patients with Alzheimer's disease who were selected from a registry of such patients. Data analyses included 1) descriptive statistics on the frequency of psychiatric symptoms and difficulties with activities of daily living and 2) logistic regression, with symptoms and functional impairment as independent variables, to test for significant changes in patients' status between stages of the Global Deterioration Scale. RESULTS: More than 50% of the patients at stage 2 displayed psychopathology, and 32% had two or more symptoms. The significant increase in psychiatric symptoms occurred between stages 3 and 4, not between stages 5 and 6 as predicted by the Global Deterioration Scale. Impairment in functional status was observed at all stages, and significant increases occurred between stages 3 and 4 as well as between stages 5 and 6. CONCLUSIONS: Psychiatric symptoms and functional impairment occur earlier than predicted by the Global Deterioration Scale, and the rate of change is also different from that specified in the scale. Separate scales to describe cognitive, clinical, and functional status may be the best way to describe the illness until better multidimensional instruments are developed.

Activities of Daily Living↗

PubMed2005

The role of a computerised case-based testing procedure in practice performance assessment.

INTRODUCTION: For postgraduate training of doctors there is a need for valid and reliable instruments to assess their daily performance. Various instruments have been suggested, some of which use incognito simulated patients (SPs). These methods are resource intensive. Computerised Case-based testing (CCT) is logistically simpler and may still predict performance well. The research question was to evaluate the predictive validity of CCT for performance. METHODS: Seventeen rheumatologists were each visited by eight incognito SPs presenting various rheumatological complaints, and scoring the performance of the rheumatologists using a predefined checklist. From this checklist a panel of experts identified essential items. In addition the rheumatologists sat a CCT test containing 55 cases with a total of 121 items. RESULTS: Negative correlations were found between the SP scores and the CCT scores. This was unexpected. Therefore, background variables on experience were used to compare both methods. The correlation between these and CCT were high and positive and with the SP scores high and negative. This pattern did not differ when using the essential items of the checklist. Reliabilities of the SP scores were markedly high. DISCUSSION: Although CCT was not predictive of SP scores, it was related to working experience. There are good reasons to assume that although SP-scores were more authentic, they were less valid than CCT scores, mainly because they focussed more on thoroughness than on efficiency in data gathering. The results underpin the assumption that for valid performance assessment the most important issue is what information about the candidate is collected and now how authentic the method is.

Clinical Competence↗

PubMed2001

[Significance of employment and unemployment in middle and advanced adult age for subjective perception of aging and realization of potentials and barriers of a responsible life].

This contribution proceeds on the assumption that occupational activities in middle and upper adulthood do offer opportunities to use and extend competences and therefore to experience self-efficacy, social participation and acceptance, whereas unemployment is associated with a constriction of personal resources which have a negative impact on subjective perceptions of ones's own aging process, potentials and barriers of leading a productive and responsible life. First, employed and unemployed subjects are compared in their scores on three psychometric scales (perceptions of age-related losses, potentials and barriers of leading a productive and responsible life) and four aspects of the "Lebenslage" (Subjective health status, Perceived social integration, Income of the household, Education). In a further step the predictive power of employment and unemployment for subjective perceptions of one's own aging process, potentials and barriers of leading a productive and responsible life when aspects of the "Lebenslage" and sociostructural variables (Age, Sex, Eastern versus western part of Germany, Areas with high versus low unemployment) are also taken into account. Results, obtained in a stratified sample of 641 subjects between 45 and 57 years, show that employed and unemployed subjects differ in subjective perceptions of one's own aging process, potentials and barriers of leading a productive and responsible life as well as in aspects of the "Lebenslage". Employment and unemployment are significant predictors of subjective perceptions of one's own aging process, potentials and barriers of leading a productive and responsible life even when aspects of the "Lebenslage" and sociostructural variables are already taken into account. Results are interpreted as support for the hypothesis that occupational activities are not only instrumental for the realization of human necessities, but that in middle and upper adulthood employment is to be regarded as a human need in itself.

Activities of Daily Living↗

PubMed2004

Improving the evaluation of therapeutic interventions in multiple sclerosis: development of a patient-based measure of outcome.

OBJECTIVES: To develop a patient-based, disease-specific measure of the health impact of multiple sclerosis (MS) for use in clinical trials and clinical practice. DATA SOURCES: People with MS. Members of the MS Society of Great Britain and Northern Ireland. METHODS: Standard psychometric methods were used to develop the Multiple Sclerosis Impact Scale (MSIS-29) in three stages. Stage 1 (item generation): questionnaire items were generated from 30 patient interviews on the impact of MS on their lives, expert opinion and literature review. Stage 2 (item reduction and scale generation): the questionnaire developed in stage 1 was administered by postal survey to 1530 randomly selected members of the MS Society. Standard item reduction techniques were used to develop a rating scale from the pool of questionnaire items. Stage 3 (psychometric evaluation): the questionnaire was evaluated for data quality, scaling assumptions, acceptability, reliability and validity in a separate postal survey of 1250 MS Society members. Responsiveness was evaluated in 55 people admitted to hospital for rehabilitation and intravenous steroid treatment of MS relapses. RESULTS: Stage 1 resulted in a 129-item questionnaire. Stage 2 resulted in a 29-item rating scale measuring the physical and psychological impact of MS. The MSIS-29 satisfied all recommended psychometric criteria for rigorous measurement. Data quality was excellent: missing data were low, item test-retest reliability was high and scale scores could be generated for over 98% of respondents. Item descriptive statistics, item convergent and discriminant validity, and factor analysis supported summing items to produce two summary scores. MSIS-29 physical and psychological scale scores showed good variability, low floor and ceiling effects, good internal consistency and test-retest reliability. Correlations with other measures and confirmation of hypotheses about group differences provided evidence for the validity of the MSIS-29 as a measure of the physical and psychological impact of multiple sclerosis. Effect sizes provided preliminary evidence for responsiveness. CONCLUSIONS: The 29-item MSIS-29 is a rigorous new measure of the physical and psychological impact of MS. All psychometric criteria were satisfied and there is preliminary evidence of responsiveness. The MSIS-29 is particularly appropriate for use in clinical trials to evaluate therapeutic effectiveness from the patient's perspective. Further critical evaluations of the MSIS-29 completed by people with neurologist-confirmed MS in different settings are suggested. Head-to-head comparisons of the psychometric properties of the MSIS-29 and other outcome measures for MS will help to determine the relative advantages of different instruments so that the choice of measures for studies can be evidence based.

Adult↗

PubMed1998

Cervical spine models for biomechanical research.

Biomechanical models have been used for the understanding of the basic normal function and dysfunction of the cervical spine and for testing implants and devices. Biomechanical models can be broadly categorized into four groups: 1) Physical models, made of nonanatomic material (e.g., plastic blocks), are often used for the testing of spinal instrumentation when only the device is to be evaluated. 2) In vitro models consisting of a cadaveric spine specimen are useful in providing basic understanding of the functioning of the spine. Human specimens are more suitable for these models than are animal specimens whenever anatomy, size (for instrumentation), and kinematics are important. Animal specimens are less costly, easier to obtain, and often have less variability but should be used with care because of the absence of anatomic fidelity with the human. 3) In vivo animal models provide the means to model living phenomena, such as fusion, development of disc degeneration, instability, and adaptive responses in segments adjacent to spinal instrumentation. Choosing the appropriate animal is important. The appropriate animal should have spinal loading, kinematics, kinetics, vertebral size, and healing-fusion rates as similar to those in humans as possible. For better interpretation of in vivo animal experimental results, in vitro biomechanical study using the same animal cadaveric specimen is useful but has not been used routinely. 4) Computer models are developed from mathematical equations that incorporate geometry and physical characteristics of the human spine and may be advantageously used for problems that are difficult to model by other means. Examples are the changes in disc and vertebral stresses in response to graded transection of facet joints and the study of changes in endplate loading caused by disc degeneration. Because these models are purely mathematical, their validation is essential. Validation is best achieved by first incorporating high-quality geometry and physical characteristics of the human spine and then comparing the model predictions with experimental observations. Sometimes an enthusiastic researcher may use a computer model beyond its validation boundary, making the model's predictions unreliable. In general, it is important to remember that a biomechanical model, similar to any other model, represents only a certain aspect of the real living human being. The aspect chosen for representation should be selected with great care. The model should be designed to answer specifically the question asked. Its predictions are valid only within the boundaries of assumptions and limitations that it incorporates.

Animals↗

PubMed2006

A simple correction for cell autofluorescence for multiparameter cell-based analysis of human solid tumors.

BACKGROUND: Corrections that have been proposed to minimize the unwanted contribution of cell autofluorescence to the total fluorescence signal often require either specialized instrumentation or the sacrifice of a data channel so as to perform a measurement that can be used to correct for autofluorescence in individual cells. Here we propose a simple cell by cell correction for autofluorescence that is suitable for multiparameter laser scanning cytometry (LSC) studies in human solid tumors that relies on the ratio of mean autofluorescence to mean total cell fluorescence (mean Flauto/mean Fltotal). This approach assumes a correlation between the autofluorescence component and the total signal in individual cells. This correction does not require specialized instrumentation, and does not sacrifice a data channel in multiparameter studies. A potential disadvantage is that errors may be introduced by the assumption of a correlation between the two components of the total fluorescence signal in individual cells in samples in which no such correlation exists. METHODS: Distributions of cell autofluorescence and total Her-2/neu cell fluorescence were obtained separately by LSC in three human breast cancer cell lines and in three samples of primary human lung cancer. In the breast cancer cell lines, autofluorescence measurements and Her-2/neu measurements were also obtained on the same cells. RESULTS: We show that there is a partial correlation between autofluorescence and total Her-2/neu/FITC fluorescence in individual cells in the three breast cancer cell lines. We also show that the results of a ratio-based autofluorescence correction agree with those based on a true cell by cell correction. Computer simulation studies suggest that in samples with no correlation between the autofluorescence component and the true probe/dye fluorescence component, the ratio correction produces robust estimates of the mean true fluorescence signal, with relatively small but systematic underestimates of the coefficient of variation of such measurements under conditions commonly encountered in the measurement of human solid tumors. CONCLUSIONS: A simple cell by cell correction for autofluorescence based on the ratio of mean Flauto to mean Fltotal can be applied in cell samples in which there is a correlation between cell autofluorescence and true probe/dye fluorescence in individual cells. In cell samples that lack this correlation, or in which it is not known whether such a correlation exists, this correction can be used with the reservation that there is a systematic but relatively small underestimation of the degree of variability of the measurements.

Breast Neoplasms↗

PubMed2004

The role of back muscle endurance, maximum force, balance and trunk rotation control regarding lifting capacity.

Evaluation of lifting capacity is widely used as a reliable instrument in order to evaluate maximal and safe lifting capacity. This is of importance in regard to planning rehabilitation programs and determining working ability. The aim of this study was to investigate the influence of basic functions on the lifting capacity measured by the progressive isoinertial lifting evaluation (PILE) and the functional capacity evaluation (FCE) tests in a lower (floor to waist) and an upper (waist to shoulder) setting and compare the two test constructs. Seventy-four female subjects without acute low back pain underwent an examination of their lifting capacities and the following basic functions: (1) strength and endurance of trunk muscles, (2) cardiovascular endurance, (3) trunk mobility and (4) coordination ability. A linear regression model was used to predict lifting capacity by means of the above-mentioned basic functions, where the F statistics of the variables had to be significant at the 0.05 level to remain in the model. Maximal force in flexion showed significant influence on the lifting capacity in both the PILE and the FCE in the lower, as well as in the upper, lifting task. Furthermore, there was a significant influence of cardiovascular endurance on the lower PILE and also of endurance in trunk flexion on the lower FCE. Additional inclusion of individual factors (age, height, weight, body mass index) into the regression model showed a highly significant association between body height and all lifting tasks. The r (2) of the original model used was 0.19/0.18 in the lower/upper FCE and 0.35/0.26 in the lower/upper PILE. The model r (2) increased after inclusion of these individual factors to between 0.3 and 0.4. The fact that only a limited part of the variance in the lifting capacities can be explained by the basic functions analyzed in this study confirms the assumption that factors not related to the basic functions studied, such as lifting technique and motor control, may have a strong influence on lifting capacity. These results give evidence to suggest the inclusion of an evaluation of lifting capacity in clinical practice. Furthermore, they raise questions about the predictive value of strength and endurance tests in regard to lifting capacity and work ability.

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