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PubMed1994

Measurement variation in method comparison studies: an empirical examination.

Procedures commonly used in rehabilitation research to analyze data from method comparison studies were examined. A simulation study was conducted in which different types of measurement variation were introduced to a reference set of range of motion (ROM) values. The test ROM data included individual data sets with random variation, alternate variation, constant variation, and proportional variation. Comparisons were made between original ROM reference values and simulated test ROM data. The statistical comparisons involved Pearson product-moment correlation, least square regression, t tests, and intraclass correlation coefficients. The individual data sets were also presented graphically using a method referred to as limits of agreement. The analyses revealed Pearson product-moment correlations, t tests, and other commonly used statistical procedures were not sensitive to different types of measurement variation in evaluating the results of method comparison investigations. The findings indicate that the limits of agreement technique, based on plotting difference scores against mean values, provided the most accurate estimation of measurement error. The advantages and limitations of various procedures to analyze agreement between rehabilitation assessment methods are described.

Bias↗

PubMed1997

Comparison of methods of measuring pulmonary artery pressure.

BACKGROUND: Pulmonary artery waveforms fluctuate because of changes in intrathoracic pressure caused by respirations. Monitoring system algorithms determine digital displays of pressure measurements on the basis of recognition, analysis, and comparison of consecutive waveforms. OBJECTIVE: To compare three methods of measuring pulmonary artery pressure during mechanical ventilation and spontaneous breathing in cardiac surgery patients with stable hemodynamics. METHODS: Pulmonary artery pressure was measured during mechanical ventilation after cardiac surgery in 53 patients; 37 of the patients were studied again after extubation. Three monitoring methods were compared: graphic strip recording, the "stop cursor" (monitor screen freezing) method, and digital-display recording. Difference scores were calculated between the methods and analyzed for frequency and direction. RESULTS: All comparisons showed differences of at least +/-3 mm Hg in measurements obtained with the three methods. During mechanical ventilation, the digital and graphic measurements of systolic pressure varied most often; 57% (30/53) of the comparisons had difference scores of at least +/-3 mm Hg. The cursor and graphic measurements of diastolic pressures varied least often; 6% (3/53) of the comparisons had difference scores of at least +/-3 mm Hg. As expected, the digital method most often gave higher results than the graphic method. During spontaneous breathing, measurements of systolic pressure varied more often (38% to 53%) than did measurements of diastolic pressure (12% to 37%). Unexpectedly, for systolic pressures, the difference between digital and graphic measurements was 3 mm Hg or more 30% (11/37) of the time, and the difference between cursor and graphic measurements was 3 mm Hg or more 53% (17/32) of the time. CONCLUSIONS: Because of physiological and technical influences, measurements of systolic and diastolic pressures in the pulmonary artery made with the digital and cursor methods were not as reliable as measurements made with the graphic method. The findings support continued use of the graphic method for accurate measurements of pulmonary artery pressure.

Adult↗

PubMed1997

Behaviour of arm venous pressure in patients with systodiastolic hypertension and in the elderly with isolated systolic hypertension in comparison with healthy controls.

The aim of our study was to evaluate the behaviour of venous pressure in patients with systodiastolic arterial hypertension as compared with elderly patients suffering from isolated systolic hypertension and with healthy controls. We studied 125 subjects subdivided into three groups: Group A, formed by 32 patients, aged between 43 and 73 years, with a mean age of 63.25+/-12.3 years, suffering from mild to moderate systodiastolic essential arterial hypertension (SDH); Group B, including 50 patients, aged between 58 and 83 years, with a mean age of 71.53+/-8.43 years, with isolated systolic hypertension (ISH); Group C, formed by 43 subjects, aged between 13 and 72 years, with a mean age of 42.91+/-17.84 years, as a healthy control group (CS). Patients observed a period of pharmacological washout for at least 15 days before the beginning of the study. All underwent a diet with a normal sodium intake. Brachial arterial pressure was always measured at 9 a.m., by using a mercury sphygmomanometer. The venous pressure was measured at the fold of the elbow on the basilic vein, using a Doppler ultrasound instrument. The SBP was similar in patients with SDH (Group A) and in those with ISH (Group B); in both groups SBP was significantly higher than in CS (Group C) (p<0.001). The DBP was significantly higher especially in patients of group A, but also in patients of group B, in comparison with subjects of group C and in patients with SDH in comparison with those with ISH. Venous pressure (VP) proved to be significantly higher in both groups of hypertensives in comparison with CS and in SDH in comparison with ISH (14.76+/-1.90 in Group A vs 12.53+/-2.39 in group B vs 8.75+/-2.02 mmHg in group C, p<0.0001). Considering ten subjects, matched for sex and age in each group, we observed again that VP values in SDH were >ISH>CS (14.3+/-2.9 vs 9.7-/+1.8 in SDH vs CS, 13.5-/+2.1 vs 10.7+/-1.9 in ISH vs CS, 15.6+/-2.2 vs 11.6+/-2.6 mm Hg in SDH vs ISH, p<0.001). In all three considered groups a significant correlation between the values of SBP and DBP with VP (p<0.001) was observed. In conclusion, data from our study show that hypertension is a disease in which both the arterial and the venous vascular beds are involved with increased pressure in both circulatory beds.

Adult↗

PubMed1998

Comparison of 3 methods of selenium assessment in cattle.

Three tests are routinely done to assess blood status of selenium in cattle: serum selenium, whole blood selenium, and glutathione peroxidase. The objective of this study was to compare the various analytical methods for determining blood selenium status in groups of mature cows and beef calves. Twenty to 30 blood samples per herd were collected from 8 beef herds in central Alberta and 1 dairy in Alberta herd twice a year from the spring of 1992 through the fall of 1995, and once from 185 spring calves in 2 beef herds in Saskatchewan. Serum and whole blood samples were submitted to 1 laboratory and whole blood samples were submitted to a 2nd laboratory. Samples for glutathione peroxidase determinations were submitted to a 3rd laboratory. Pearson's correlation coefficients and Cohen's kappa were calculated for each possible comparison among the different measures. The best agreement was observed between serum and whole blood analysis within Laboratory A. The remaining comparisons reflected poor agreement. Comparison of herd-level assessment resulted in better agreement than comparison of individual sample results among laboratories and procedures for all combinations tested. Serum selenium analysis was the only laboratory procedure for which external reference material was utilized. Serum selenium, whole blood selenium, and glutathione peroxidase measure different compartments of the blood selenium pool. The time frame of interest, supplementation practices, and the stability of recent dietary intake determine the optimum assessment method for individual animals or herds. Determination of the serum status or of blood selenium is more consistently measured at the herd-level than for individual samples.

Animals↗

PubMed1998

Computer-based production of bite mark comparison overlays.

Bite mark comparison protocols include measurement and analysis of the pattern, size, and shape of teeth against similar characteristics observed in an injury on skin or a mark on an object. The physical comparison of tooth position often depends upon transparent acetate overlays to detect similarities or differences between the teeth and the bite mark. Several methods are used to produce life-sized comparison overlays. The perimeter of the biting edges of the anterior teeth are usually recorded to produce facsimile images called hollow volume overlays. Some investigators hand-trace these outlines from dental study casts, or from bite exemplars produced in wax, styrofoam, or similar materials. Some use hand-traced outlines from xerographic images produced with office photocopiers that are calibrated to produce life-sized final images. Others use radiographic images and toneline photography of wax exemplars filled with radio-opaque materials, such as metal filings or barium sulfate. Dependence upon subjective input by the odontologist to trace these images manually is considered problematic. This is because the errors incorporated at any production stage are increased in the final product. The authors have developed a method to generate accurate hollow volume overlays using computer-based techniques. A PowerPC Macintosh computer, flatbed scanner, and Adobe Photoshop (a popular graphical interface application) are used to acquire, select, arrange and export detailed data from class and individual characteristics of a suspect's teeth to acetate film loaded in a high-resolution laser printer. This paper describes this technique to enable the odontologist to produce high-quality, accurate comparison overlays without subjective input.

Bites, Human↗

PubMed1990

Use of Medicare data in international comparisons.

This paper provides a detailed description of the statistical systems of the U.S. Medicare program and discusses how these data bases can be used for health policy analyses and for international comparisons of health systems at the microeconomic level. First, the Medicare program in the context of the entire U.S. health care financing and delivery system is described. Second, the Medicare data collection process and the detailed data elements collected as part of the various Medicare administrative and research data bases are discussed in detail. Third, the use of these microdata for international comparisons of medical effectiveness, incentive effects of alternative reimbursement systems, technology assessment, service use by consumers, and industry impacts is suggested. International comparisons of health systems based on microdata are essential for understanding the underlying dynamics of health systems as well as for attributing performance to specific features or policies.

Centers for Medicare and Medicaid Services, U.S.↗

PubMed1996

Post-natal depression in an urban area of Portugal: comparison of childbearing women and matched controls.

The point prevalence of depression measured on one occasion between 2 and 5 months after childbirth was estimated to be 13.1% in 352 mothers living in urban Portugal; the criterion was a score of 13 or more on a translated version of the Edinburgh Post-natal Depression Scale (EPDS). More detailed comparisons were made between a subgroup of 118 mothers and 118 matched controls who had not borne a child in the previous 2 years. Post-natal women were twice as likely as non-childbearing controls to meet the EPDS criterion for depression In comparison with controls, they were also more severely depressed as judged by their total scores on another questionnaire, the Zung Scale. Comparisons of individual symptom scores (Zung Scale) showed that childbearing women, as a whole, reported more somatic symptoms than controls, but when only those women judged to be depressed or dysphoric by the EPDS were compared, this difference disappeared. Stepwise logistic analyses of symptoms contributing to the categorization of a 'case' of post-natal versus non-post- natal depression did not reveal any very clear divergences in self-reported psychopathology. In childbearing women, two factors were found significantly to contribute to higher depression scores; women with more children and those from lower socio-economic groups were most at risk.

Adult↗

PubMedDate not supplied

[Normal values of the shoulder strength in dependency on age and gender--comparison with the constant, UCLA, ASES scores and SF36 health survey].

AIM: The purpose of this study was to establish normal strength values of shoulder abduction in a male and female population aged between 6 to 90 years. These values were compared to the sex- and age-related values given by Constant for an Irish population, referred to as Constant 1991. Further strength values resulting from fixation of the measuring device at the deltoid insertion or at the wrist were compared. The assessment and comparison of shoulder function using different shoulder scores (Constant, UCLA, ASES) and the SF-36 was another aim of this study. METHOD: 120 male and 120 female probands were examined. For interpretation age- and sex-related groups of 20 probands each were used (group 1: 6 - 15 years; group 2: 16 - 30 years; group 3: 31 - 45 years; group 4: 46 - 60 years; group 5: 60 - 70 years, group 6: 71 - 90 years). Subjective and objective clinical parameters were registered, shoulder abduction strength was obtained using an isometric measuring device with fixation points at the deltoid insertion and at the wrist and the respective torque values were calculated. The shoulder function was quantified using Constant, UCLA and ASES scores. With the exception of group 1, the quality of life was measured with the SF-36 health-status questionnaire. RESULTS: Normal values of the shoulder abduction strength and valuation according to the Constant score are given for a German reference group related to age and gender. In addition to the Constant score more values for children are given. Strength values measured at the deltoid insertion (fixation point 1, FP1) and wrist (fixation point 2, FP2) are in a linear relation. Thus FP1 = 2.5 x FP2 and FP2 = 0.4 x FP1. If torque values instead of strength are used, 25 points correspond to 50 Nm. Total score values calculated by the use of the Constant score (methods published 1991) were markedly higher in groups 3 - 6 related to the values of Constant in the Irish population; the main reason is the higher abduction strength in our population. There exists a good relation between the Constant, UCLA and ASES scores (Constant 1991). The results of the SF-36 health survey were similar to the results of Bullinger et al. 1996. CONCLUSION: The normal values of C. R. Constant of an Irish population differ in part to those of our groups due to the different strength values. Our values may be more representative for German patients. The linear regression between strength values measured at a fixation point at the deltoid insertion or the wrist facilitates the calculation of each point from the other. This allows a comparison of the results of studies with different fixation points. The additional calculation of the torque allows a comparison of different studies independently of the fixation point of the strength measuring device.

Adolescent↗

PubMed2006

Identification of differential item functioning using item response theory and the likelihood-based model comparison approach. Application to the Mini-Mental State Examination.

BACKGROUND: An important part of examining the adequacy of measures for use in ethnically diverse populations is the evaluation of differential item functioning (DIF) among subpopulations such as those administered the measure in different languages. A number of methods exist for this purpose. OBJECTIVE: The objective of this study was to introduce and demonstrate the identification of DIF using item response theory (IRT) and the likelihood-based model comparison approach. METHODS: Data come from a sample of community-residing elderly who were part of a dementia case registry. A total of 1578 participants were administered either an English (n = 913) or Spanish (n = 665) version of the 21-item Mini-Mental State Examination. IRT was used to identify language DIF in these items with the likelihood-based model comparison approach. RESULTS: : Fourteen of the 21 items exhibited significant DIF according to language of administration. However, because the direction of the identified DIF was not consistent for one language version over the other, the impact at the scale level was negligible. CONCLUSIONS: IRT and the likelihood-based model comparison approach comprise a powerful tool for DIF detection that can aid in the development, refinement, and evaluation of measures for use in ethnically diverse populations.

Aged↗

PubMed1995

Massage by nurses in the United States and the People's Republic of China: a comparison.

Massage performed by a Chinese nurse is described as observed by the author. A brief history of both Eastern and Western massage is presented. A comparison of theory, indications, methods, and outcomes of massage as performed by nurses from the United States (U.S.) and the People's Republic of China is made. The comparison is based on nursing texts and journals printed in the U.S., the author's personal experience in the People's Republic of China, correspondence with a nurse from the People's Republic of China, and texts and journals printed in English in the People's Republic of China. Massage as a nursing intervention differed on many points of comparison between the two countries. Chinese nurses perform massage over the meridians which are the channels for Chi--the life force of energy. Nurses in the U.S. perform massage over tense muscles. Massage performed by U.S. nurses involves three to five strokes while Chinese nurses use dozens of strokes. In China, massage is considered curative; in the U.S. it is mostly palliative.

Acupressure↗

PubMed2006

Mixed comparison of stroke prevention treatments in individuals with nonrheumatic atrial fibrillation.

BACKGROUND: We aimed to identify different stroke prevention treatments for atrial fibrillation assessed in randomized controlled trials and to compare them within a single evidence synthesis framework. METHODS: We updated the Cochrane review on anticoagulants and antiplatelet therapy for nonrheumatic atrial fibrillation to include randomized controlled trials published between January 2000 and March 2005 identified via the CENTRAL database and MEDLINE. A mixed-treatment comparison method was used to combine direct within-trial, between-treatment comparisons with indirect trial evidence while maintaining randomization. RESULTS: Data were combined from 19 clinical trials that included 17 833 patients randomized to 9 treatment strategies, including placebo. For prevention of ischemic stroke, adjusted standard-dose warfarin sodium (relative rate [RR], 0.35; 95% credible interval [CrI], 0.24 to 0.52), adjusted low-dose warfarin (RR, 0.35; 95% CrI, 0.19 to 0.60), ximelagatran (RR, 0.34; 95% CrI, 0.18 to 0.61), and aspirin (RR, 0.64; 95% CrI, 0.44 to 0.88) were all associated with a significantly lower rate of ischemic stroke compared with placebo. For major and fatal bleeding episodes, there was some evidence of an increased risk for all treatments but none were statistically significant. Assuming a baseline risk of 51 ischemic stroke events per 1000 person-years, it can be estimated that adjusted standard-dose warfarin could prevent 28 (95% CrI, -37 to -19) ischemic strokes at the expense of 11 (95% CrI, -1 to +39) major or fatal bleeding episodes. In comparison, aspirin could prevent 16 (95% CrI, -26 to -5) ischemic strokes at the expense of 6 (95% CrI, -3 to +27) major or fatal bleeding episodes. CONCLUSIONS: A lower rate of ischemic stroke and a higher rate of major bleeding episodes were found to be associated with oral anticoagulants compared with aspirin, and both anticoagulants and aspirin were found to be associated with a reduction in the rate of stroke compared with placebo.

Anticoagulants↗

PubMed1997

Classification and staging of dementia of the Alzheimer type: a comparison between neural networks and linear discriminant analysis.

OBJECTIVE: To examine the utility of artificial neural networks (ANNs) for differentiating patients with Alzheimer disease from healthy control subjects and for staging the degree of dementia. DESIGN: Comparison of the classification abilities of ANNs with the statistical technique of linear discriminant analysis (LDA) using the results of 11 neuropsychological tests as predictors. PARTICIPANTS: Ninety-two patients with a diagnosis of probable Alzheimer disease (referred from a geriatric clinic) and 43 elderly control subjects (independently solicited). The patients met National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable dementia, with clinical ratings of dementia severity derived from the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX). MAIN OUTCOME MEASURES: Classifications between and within groups were determined by using LDA and ANNs, and more detailed comparisons of the 2 methods were performed by using chi2 analyses and unweighted and weighted kappa statistics. RESULTS: Linear discriminant analysis correctly identified 71.9% of cases. Artificial neural networks, trained to classify the subjects using the same data, correctly classified 91.1% of the cases. Subsidiary analyses showed that although both techniques effectively discriminated between the control subjects and patients with dementia, the ANNs were more powerful in discriminating severity levels within the dementia population. The analyses for goodness of fit revealed that the ANN classification produced a better fit to the actual data. A comparison of the weighted proportion of agreement between the criterion and predictor variables also showed that the ANNs clearly outperformed LDA in classification accuracy for the full data set and patients-only data set. CONCLUSION: The results demonstrate the utility of ANNs for group classification of patients with Alzheimer disease and elderly controls and for staging dementia severity using neuropsychological data.

Aged↗

PubMed1999

A comparison study of an elementary school-based health center: effects on health care access and use.

OBJECTIVE: To assess the effects of an elementary school-based health center (SBHC) on access to and the use of physical and mental health services by children aged 4 to 13 years. STUDY DESIGN: A retrospective cohort analysis of parent surveys from a comparable intervention (SBHC) and a comparison of urban elementary schools. INTERVENTION: Elementary SBHC services, including preventive physical health care; the care of minor short-term illnesses, injuries, and stable ongoing medical conditions, dental screenings; and mental health counseling. PARTICIPANTS: All parents of students at both schools were asked to complete a survey. Return rates on the survey were 78.3% (570/728) and 77.0% (440/571) at the intervention and comparison schools, respectively. MAIN OUTCOME MEASURES: The use of health services, access to health services, and health service satisfaction. RESULTS: Compared with respondents at comparison schools, respondents whose children had access to an SBHC had less difficulty (P = .01) receiving physical health care for their children, ie, treatment of illnesses and injuries, immunizations, and physical examinations (odds ratio, 0.66; 95% confidence interval, 0.48-0.91). Access to an SBHC was independently and significantly related to less emergency department use (odds ratio, 0.63; 95% confidence interval, 0.40-0.99; P<.05), a greater likelihood of having had a physician's visit since the school year began (odds ratio, 1.92; 95% confidence interval, 1.39-2.65; P<.01), and a greater likelihood of having had an annual dental examination (odds ratio, 1.36; 95% confidence interval, 1.01-1.83; P<.05). Measured by a 12-item scale, respondents who reported the SBHC as their most-used health service were significantly more satisfied with their service than respondents who mostly used community clinics (z=-5.21; P<.01) or hospital clinics (z=-4.03; P<.01). CONCLUSIONS: Independent of insurance status and other confounding variables, underserved minority children with SBHC access have better health care access and use than children without SBHC access, signifying that SBHCs can be an effective component of health delivery systems for these children.

Adolescent↗

PubMed1996

Extremely low-birth-weight children and their peers. A comparison of school-age outcomes.

OBJECTIVE: To document 7-year developmental and educational outcomes in a cohort of predominantly white, middle-class, extremely low-birth-weight (ELBW, < 1000 g) children to address the incidence of increased developmental disability and the need for special educational services. DESIGN: Observational study. PATIENTS: Fifty-four ELBW children and 58 comparison children, who were matched for race, gender, and socio-economic status (30 with low birth weights [1500-2500 g] and 28 with birth weights > 2500 g). The ELBW cohort was drawn from 104 presurfactant survivors born between 1984 and 1986 and cared for in a single hospital. SETTING: Suburban, university-based tertiary referral center. MAIN OUTCOME MEASURES: Teachers' reports of classroom placement and special education services and tests of cognitive, motor, language, and visual-motor integration abilities were studied. RESULTS: Twenty-seven (50%) of 54 ELBW children were in regular classrooms with no special services compared with 21 (70%) of 30 in the low-birth-weight group and 27 (93%) of 28 in the full-term group, indicating a significant trend toward increasing need for special services with decreasing birth weight across the 3 groups (P < .001). The ELBW group scored significantly lower than the comparison groups on all tests, although generally within the average range. Seventy-nine percent of ELBW children had average cognitive scores, but they averaged 14 to 17 points lower than the 2 comparison groups. Twenty percent of the ELBW children had significant disabilities including cerebral palsy, mental retardation, autism, and low intelligence with severe learning problems. CONCLUSIONS: Even with optimal socioeconomic environments, 20% of ELBW children are significantly disabled, and 1 of every 2 ELBW children requires special educational services. Objective testing pinpointed weakness on all measures compared with matched peer groups.

Case-Control Studies↗

PubMed1992

Clinical and biologic response to clozapine in patients with schizophrenia. Crossover comparison with fluphenazine.

Twenty-one patients with schizophrenia who met criteria for neuroleptic treatment resistance or intolerance participated in a crossover, placebo-controlled, double-blind comparison of long-term typical neuroleptic and clozapine treatment. Clozapine significantly reduced total as well as positive and negative symptoms in comparison with both fluphenazine and placebo. Of the 21 patients, eight (38%) showed clozapine superiority on the basis of prospective response criteria. High levels of extrapyramidal side effects during fluphenazine treatment and later onset of illness were clinical predictors of clozapine superiority. Clozapine and fluphenazine equally reduced plasma homovanillic acid levels in comparison with placebo, although fluphenazine but not clozapine increased plasma prolactin level. A striking biologic difference between clozapine and fluphenazine was clozapine's enhancement of indexes of noradrenergic activity. Superior clozapine response was predicted by low ratios of cerebrospinal fluid homovanillic acid to 5-hydroxyindoleacetic acid, consistent with the notion that balance between dopaminergic and serotoninergic systems is important for clozapine's mechanism of action.

Adult↗

PubMed2003

Alterations in stress cortisol reactivity in depressed preschoolers relative to psychiatric and no-disorder comparison groups.

BACKGROUND: Despite the robust and widely replicated finding of elevated hypothalamic-pituitary-adrenal (HPA) axis reactivity in depressed adults, studies of depressed children have yielded ambiguous findings. Animal models of early depression and studies of children experiencing early psychosocial deprivation have suggested that alterations in HPA axis reactivity are evident in early "depressive-like" conditions. The current study is, to our knowledge, the first investigation of HPA axis reactivity in very young children with a clinical depressive syndrome for which content validity has been established. METHODS: Depressed, psychiatric, and no-disorder comparison children aged 3 through 5.6 years were studied for HPA axis reactivity in response to experimental psychosocial stressors. The children were diagnosed using a developmentally appropriate, structured psychiatric interview. Salivary cortisol was obtained at 3 time points during a laboratory assessment before and after stressors involving separation from the parent and frustrating tasks. RESULTS: Repeated measures of multivariate analysis of variance revealed a significant interaction between the diagnostic group and 2 cortisol percent change scores. Depressed preschoolers displayed a pattern of increasing cortisol levels throughout the assessment in response to both separation and frustration stressors. In contrast, both comparison groups showed decreasing cortisol levels in response to the separation stressor. All groups displayed increasing cortisol levels in response to frustrating tasks. Preschoolers with a presumptive melancholic depressive subtype displayed these alterations at a greater magnitude relative to comparison groups. CONCLUSIONS: To our knowledge, these findings are the first to demonstrate altered HPA axis reactivity in depressed preschoolers. These alterations are consistent with those described in depressed adults and in animal models of early depression. These findings provide evidence for possible continuity of HPA axis alterations in depressive disorders across the lifespan and are discussed in the context of prior studies of HPA axis reactivity in clinically depressed children and adolescents, suggesting that younger age and inpatient status are features associated with altered HPA axis reactivity.

Arousal↗

PubMed1998

Renal length in Chinese children: sonographic measurement and comparison with western data.

PURPOSE: The purpose of this study was to determine the normal range of renal length in Hong Kong Chinese children and compare it with Western data. METHODS: Two hundred fifty children undergoing routine abdominal sonography were examined prospectively, and the maximum length of 1 kidney per child was recorded. Ages ranged from newborn to 19 years, and there were 109 girls and 141 boys. Similar data from Australian children involved maximum lengths of both kidneys in 554 children ranging in age from newborn to 14 years. There were 361 girls and 193 boys. No children had known renal disease. RESULTS: There was no statistically significant difference between the mean renal lengths of girls and boys. Statistical comparison of the data from Hong Kong and Australia showed no significant difference except in the 8-12 month age group (this difference is unlikely to be clinically significant). Although direct statistical comparison with published data on kidney lengths in 203 U.S. children was not possible, plots of the three sets of data were strikingly congruent. CONCLUSIONS: Despite expectations that smaller body size in Hong Kong children might equate to smaller kidneys, comparison with 2 sets of Western data showed no clinically significant difference in renal length between the 3 groups.

Adolescent↗

PubMed1999

Flexible structural comparison allowing hinge-bending, swiveling motions.

We present an efficient method for flexible comparison of protein structures, allowing swiveling motions. In all currently available methodologies developed and applied to the comparisons of protein structures, the molecules are considered to be rigid objects. The method described here extends and generalizes current approaches to searches for structural similarity between molecules by viewing proteins as objects consisting of rigid parts connected by rotary joints. During the matching, the rigid subparts are allowed to be rotated with respect to each other around swiveling points in one of the molecules. This technique straightforwardly detects structural motifs having hinge(s) between their domains. Whereas other existing methods detect hinge-bent motifs by initially finding the matching rigid parts and subsequently merging these together, our method automatically detects recurring substructures, allowing full 3 dimensional rotations about their swiveling points. Yet the method is extremely fast, avoiding the time-consuming full conformational space search. Comparison of two protein structures, without a predefinition of the motif, takes only seconds to one minute on a workstation per hinge. Hence, the molecule can be scanned for many potential hinge sites, allowing practically all C(alpha) atoms to be tried as swiveling points. This algorithm provides a highly efficient, fully automated tool. Its complexity is only O(n2), where n is the number of C(alpha) atoms in the compared molecules. As in our previous methodologies, the matching is independent of the order of the amino acids in the polypeptide chain. Here we illustrate the performance of this highly powerful tool on a large number of proteins exhibiting hinge-bending domain movements. Despite the motions, known hinge-bent domains/motifs which have been assembled and classified, are correctly identified. Additional matches are detected as well. This approach has been motivated by a technique for model based recognition of articulated objects originating in computer vision and robotics.

Algorithms↗