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PubMedDate not supplied

Determination of moisture, starch, protein, and fat in common beans (Phaseolus vulgaris L.) by near infrared spectroscopy.

The presence of moisture, starch, protein, and fat was determined in common beans (Phaseolus vulgaris L.) by near infrared (NIR) spectroscopy without any previous sample pretreatment except grinding. A set of 96 samples was used to calibrate the instrument by modified partial least-squares regression. The following statistical results were achieved: standard error of calibration (SEC) = 0.31 and square correlation coefficient (R2) = 0.96 for moisture; SEC = 0.76 and R2 = 0.92 for starch; SEC = 0.39 and R2 = 0.98 for protein; and SEC = 0.14 and R2 = 0.80 for fat. To validate the calibration, a set of 25 bean samples was used. Standard errors of prediction were 0.39, 0.90, 0.56, and 0.13 for moisture, starch, protein, and fat, respectively, and R2 for the regression of measurements by the reference method versus NIR analysis were 0.94, 0.88, 0.94, and 0.74 for moisture, starch, protein, and fat, respectively. To compare the results obtained for all 4 components of the validation set by NIR spectroscopy with those obtained by the reference methods, linear regression and paired t tests were applied, and the methods did not give significantly different results, P = 0.05.

Calibration↗
PubMed1994

Basic science curriculum during residency: justification based on in-training examination scores.

The American Board of Surgery is increasing its emphasis on competency in surgical basic science as part of residency training. The 1991 American Board of Surgery In-Training Examination (ABSITE) contained 135 questions designated as basic science to assess residents' knowledge. We reviewed the separate progression of scores in clinical and basic sciences at Wayne State University (WSU) surgical residency and nationally through the 1991 ABSITE report. Regression analysis of WSU data yielded a slope (% correct answers per postgraduate year) of 5.3 for clinical and 2.4 for basic science scores (P < 0.001 by t-statistic applied to regression slopes). These data imply a progression of knowledge during residency but at a significantly slower rate for basic science. The national data confirm this trend, although we were unable to evaluate it statistically. This situation illustrates the need for organized teaching of clinically relevant basic science as part of a residency curriculum.

Curriculum↗
PubMed1993

Estimation of design effects and diarrhea clustering within households and villages.

The degree to which diarrheal disease clustered within households and within villages among preschool age children was examined using data from four population-based prevalence surveys undertaken in Malawi, Zambia, Indonesia, and Nepal over the past decade. The design effect for each cluster survey was calculated using the diarrhea prevalence, the cluster sizes, and the magnitude of diarrhea clustering within the sampling unit (villages). A recently developed statistical method, alternating logistic regression, was used to estimate disease associations within households of up to nine preschool age children residing within villages of up to 589 such children. Pairwise odds ratios estimating diarrhea clustering within villages ranged from 1.03 (95% confidence interval (CI) 1.01-1.07) in Zambia to 2.19 (95% CI 1.73-2.78) in Indonesia. The design effects ranged from 2.07 (95% CI 1.26-3.19) in Zambia to 7.93 (95% CI 5.16-11.52) in Indonesia. Design effects were strongly dependent on cluster size. The design effects for clusters of size 50 would have ranged from 1.38 to 4.73. Pairwise odds ratios for diarrhea clustering within households ranged from 1.88 (95% CI 1.61-2.19) in Nepal to 10.05 (95% CI 8.46-11.94) in Indonesia. Household odds ratios were always larger than village odds ratios. The village and household pairwise odds ratios adjusted for age, the type of latrine used by the household, and presence of a market in the village were slightly higher than the unadjusted odds ratios. Alternating logistic regression provided useful estimates of disease clustering within villages and household while allowing for covariate adjustment.

Child, Preschool↗
PubMedDate not supplied

Knowledge of statistical methods and their implications for clinical practice: a survey of paediatricians.

Improvements in computer software have contributed to an increase in the use of multivariate statistical analyses e.g. multipLe regression in recent times. Our aim was to assess the familiarity with, and understanding of these complex statistical methods among Irish paediatricians. Questionnaires were sent to all paediatric specialist registrars (SpRs) and consultants in the Republic of Ireland. The questionnaire detailed information about clinical practice, and contained a short quiz on statistical methods. 137 questionnaires were distributed, and 62 (45.6%) were returned. Eighty four percent of respondents aimed to read journals weekly but only 46.7% managed to. The commonest journals used were; Archives of Disease in Childhood (93%), Pediatrics (53%), British Medical Journal (46%) and Journal of Paediatrics (45%). 28 of 61 (45.9%) of respondents have had further training in statistics. Only 19% felt they had a clear understanding of regression. Fifty-eight of 62 respondents (93.5%) completed the short test. The average score was 5.1/10. Sixty seven percent of questions on basics were answered correctly, 37.9% of questions on application of tests were answered correctly and 25.8% of questions on regression were answered correctly. Only 3.4% answered all questions on regression correctly. The overall knowledge of advanced statistical methods was poor. There is a poor overall understanding of the concept of regression, despite its increasingly common use.

Health Knowledge, Attitudes, Practice↗
PubMed1986

Phase II study of the three-drug combination of mitomycin C, CCNU, and methotrexate (MCM) in advanced non-small cell lung cancer.

Ninety-two patients with advanced non-small cell lung cancer, 51 without prior chemotherapy exposure, were treated with the combination of mitomycin C, lomustine (CCNU), and methotrexate (MCM). Overall, the regression rate was 33%, the median regression duration 4.9 months, and the median survival 4.9 months. Patients with ECOG performance scores (PSs) of 0-1 had a statistically significant higher regression rate than did patients with ECOG PSs of 2-3 (43% versus 15%; p = 0.005) as did patients without prior chemotherapy (41% versus 22%; p = 0.05). Cell type and prior chemotherapy exposure did not affect regression duration, time to progression, nor survival. Subjective toxicity was quite acceptable. Cumulative myelosuppression was the most significant objective toxicity. MCM is a relatively effective combination chemotherapy regimen, even in patients with prior chemotherapy exposure (predominantly doxorubicin and cisplatin-based chemotherapy).

Adult↗
PubMed2004

Estimating the input function non-invasively for FDG-PET quantification with multiple linear regression analysis: simulation and verification with in vivo data.

A novel statistical method, namely Regression-Estimated Input Function (REIF), is proposed in this study for the purpose of non-invasive estimation of the input function for fluorine-18 2-fluoro-2-deoxy- d-glucose positron emission tomography (FDG-PET) quantitative analysis. We collected 44 patients who had undergone a blood sampling procedure during their FDG-PET scans. First, we generated tissue time-activity curves of the grey matter and the whole brain with a segmentation technique for every subject. Summations of different intervals of these two curves were used as a feature vector, which also included the net injection dose. Multiple linear regression analysis was then applied to find the correlation between the input function and the feature vector. After a simulation study with in vivo data, the data of 29 patients were applied to calculate the regression coefficients, which were then used to estimate the input functions of the other 15 subjects. Comparing the estimated input functions with the corresponding real input functions, the averaged error percentages of the area under the curve and the cerebral metabolic rate of glucose (CMRGlc) were 12.13+/-8.85 and 16.60+/-9.61, respectively. Regression analysis of the CMRGlc values derived from the real and estimated input functions revealed a high correlation (r=0.91). No significant difference was found between the real CMRGlc and that derived from our regression-estimated input function (Student's t test, P>0.05). The proposed REIF method demonstrated good abilities for input function and CMRGlc estimation, and represents a reliable replacement for the blood sampling procedures in FDG-PET quantification.

Algorithms↗
PubMed1990

[Analysis of correlations between the content of various elements in hard tissues of milk teeth with and without caries].

Using the method of atomic absorption spectrometry the levels of calcium, magnesium, zinc, iron, strontium, nickel, manganese, copper were determined in the hard tissues of milk teeth with and without caries and the interrelations between these elements were analysed The obtained results were subjected to statistical analysis with an IMP 85 m computer. In the present study the analysis of the interrelations between elements was based on correlations and regression analyses. Many statistically significant interrelations were revealed between Mn and Fe, Mn and Zn, Mn and Cu, Mn and Ni, Fe and Zn, Fe and Cu, Fe and Ni, Zn and Cu, Zn and Ni. A decrease of the correlation coefficients was noted in carietic teeth. For the highly correlated elements equations of simple regression were calculated. A significant correlations was noted between caries and the levels of Mg, Zn, Fe, Sr, Ni, Mn, Cu in the hard tissues in milk teeth. The carietic milk teeth contained less Mg, Fe, Sr, Ni, Mn and Cu and much more Zn as compared to teeth without caries.

Dental Caries↗
PubMed2002

Improved statistical characterization of prosthetic heart valve hydrodynamics using a performance index and regression analysis.

BACKGROUND AND AIMS OF THE STUDY: The ISO 5840 Standard (Cardiovascular implants - Cardiac valves) currently requires a minimum of three test samples per size for hydrodynamic testing. Typically, the only statistical analysis performed is a descriptive analysis, with the mean (+/- SE) given for each size and cardiac output (CO). The study aim was to develop better statistical methods, incorporating regression analysis of a performance index, equal to the effective orifice area divided by the tissue annulus area. The analysis is performed on the full dataset, with size and CO as independent variables. METHODS: Hydrodynamic data of Ionescu-Shiley pericardial valves from a published study were used to compare the two analysis methods. Three samples each of size 19, 23 and 27 mm valves were tested at COs of 4.2, 5.6, 7.0 and 8.4 l/min. Descriptive statistics were performed for each size and CO. Regression analysis was also performed on the full dataset. Confidence intervals (CI) were calculated for each statistical method and compared. RESULTS: The regression equation that best fitted the data was: Performance Index (PI) = -1.63 + (0.011 x CO) + (0.167 x size) - (0.0036 x size2). All four parameter estimates were significantly different from zero (p <0.02). The SE of the mean was 0.015 for COs of 4.2 or 8.4 l/min, and 0.013 for COs of 5.6 or 7.0 l/min, less than that of nine of 12 of the individual descriptive analysis. CI for the regression analysis were substantially tighter, averaging one-third the width of those of the descriptive statistics. CONCLUSION: The tighter CI resulting from the regression analysis allows a better comparison of the PI to an objective performance criterion. Such methods should be considered for inclusion in the new version of the ISO 5840 standard for prosthetic heart valves.

Aortic Valve↗
PubMed1990

Accuracy of formulae for calculating left ventricular volumes of the equine heart.

Echocardiography may be an accurate method of measuring left ventricular (LV) volumes and mass of the horse's heart. If so, studies of the heart size and hypertrophy would be possible. This study evaluated geometric models of the external and internal LV shapes, to determine which could be applied to echocardiographic measurements. We preserved 30 horses' hearts and measured their dimensions and cross sectional areas. These measurements were entered into seven formulae representing different geometric models of the ventricle and its chamber. We derived a correction factor to estimate the long axis as a fixed proportion of the external diameter, so that volumes could be determined from an M-mode or a cross sectional echocardiogram. Statistical analysis of the regressions of known volumes against calculated volumes measured by water displacement, demonstrated that the ellipsoid formula using cross sectional areas was very accurate in representing the external shape of the left ventricle (slope = 1.01 r2 = 96.3) and its chamber (slope = 0.83, r2 = 94.3). Myocardial volume, measured by subtracting internal (chamber) volume from external volume, was also calculated accurately (slope = 1.01, r2 = 96.5). The ellipsoid formula using directly measured diameter was only slightly less accurate. LV mass could be calculated by applying the specific gravity of equine myocardium, 1.05, to the myocardial volume. Formulae recommended for evaluating are, with M-mode echocardiography: [equation: see text] and with 2D echocardiography [equation: see text] where De is the external diameter, Di is the internal diameter, Ae the external area and Ai the internal area.

Animals↗
PubMed2005

Variability of cerebral hemoglobin concentration in very preterm infants during the first 6 hours of life.

Cerebral hemoglobin concentration (cHbc), a major determinant of oxygen transport capacity in the brain, shows a considerable variability due to physiological and methodological factors. In order to determine the (relative) contribution of these factors, the cHbc variability within the first 6 hours of life was studied in 28 very preterm infants using near infrared spectrophotometry (NIRS). Mean cHbc values were 46.4 +/- 14.1 micromol/l (2.75 +/- 0.84 ml/100 g). Is the variability in cHbc related to the methodology of cHbc measurements or to physiological variables? A statistical model of stepwise regression (backward selection) with 13 independent variables and with cHbc as a dependent variable showed that, from the total variability of +/- 14.1 micromol/l, only 3.7 micromol/l (26%) were of methodological origin, while the major portion, 9.3 micromol/l (66%) were related to four physiological variables: birth weight, gestational age, blood glucose and transcutaneous carbon dioxide tension. The remaining 1.1 micromol/l (7.8%) were unexplained. We conclude that NIRS, which allows continuous monitoring of cerebral oxygenation and metabolism even in the first hours of postnatal life, is a valid technique to measure cHbc in very preterm infants. The major portion of the large variability of early cHbc registrations can be attributed to physiological factors.

Age Factors↗
PubMed2000

Chemoprevention of gastric dysplasia: randomized trial of antioxidant supplements and anti-helicobacter pylori therapy.

BACKGROUND: Previous research has identified a high risk of gastric carcinoma as well as a high prevalence of cancer precursor lesions in rural populations living in the province of Nariño, Colombia, in the Andes Mountains. METHODS: A randomized, controlled chemoprevention trial was conducted in subjects with confirmed histologic diagnoses of multifocal nonmetaplastic atrophy and/or intestinal metaplasia, two precancerous lesions. Individuals were assigned to receive anti-Helicobacter pylori triple therapy and/or dietary supplementation with ascorbic acid, beta-carotene, or their corresponding placebos. Gastric biopsy specimens taken at baseline were compared with those taken at 72 months. Relative risks of progression, no change, and regression from multifocal nonmetaplastic atrophy and intestinal metaplasia were analyzed with multivariate polytomous logistic regression models to estimate treatment effects. All statistical tests were two-sided. RESULTS: All three basic interventions resulted in statistically significant increases in the rates of regression: Relative risks were 4.8 (95% confidence interval [CI] = 1.6-14.2) for anti-H. pylori treatment, 5. 1 (95% CI = 1.7-15.0) for beta-carotene treatment, and 5.0 (95% CI = 1.7-14.4) for ascorbic acid treatment in subjects with atrophy. Corresponding relative risks of regression in subjects with intestinal metaplasia were 3.1 (95% CI = 1.0-9.3), 3.4 (95% CI = 1.1-9.8), and 3.3 (95% CI = 1.1-9.5). Combinations of treatments did not statistically significantly increase the regression rates. Curing the H. pylori infection (which occurred in 74% of the treated subjects) produced a marked and statistically significant increase in the rate of regression of the precursor lesions (relative risks = 8.7 [95% CI = 2.7-28.2] for subjects with atrophy and 5.4 [95% CI = 1.7-17.6] for subjects with intestinal metaplasia). CONCLUSIONS: In the very high-risk population studied, effective anti-H. pylori treatment and dietary supplementation with antioxidant micronutrients may interfere with the precancerous process, mostly by increasing the rate of regression of cancer precursor lesions, and may be an effective strategy to prevent gastric carcinoma.

Adult↗
PubMed1994

Relationship between the excretion of protostrongylid larvae in sheep in north-west Spain and climatic conditions.

The relationship between different climatic factors (temperature, relative humidity and rainfall) and the pattern of lungworm larval excretion was studied in sheep under a continuous grazing pattern in North-west Spain, where the climate is intermediate between sub-humid Mediterranean with an Atlantic tendency and European Atlantic. Over a period of one year, 44 animals were sampled once a month at random from a flock of 80 Galician breed sheep, all over 4 years old. Faeces were taken directly from the rectum and the number of first stage larvae per gram of faeces was determined for each animal, and the species of Protostrongylidae (Nematoda) identified. Larval excretion was irregular during the study. The prevalence and intensity of infection were greater in the colder months (40.9%; x = 12.3 +/- 40.4) and less in the warmer months (21.9%; mean = 0.7 +/- 2.7). The species of Protostrongylidae identified and prevalences (%) were Neostrongylus linearis (71.5), Muellerius capillaris (18.8) and Cystocaulus ocreatus (9.7). Between November and March, with low temperatures, the prevalence and intensity of parasitism with N. linearis and M. capillaris were greater than in the months with high temperatures (May to September). Multiple linear regression analysis showed statistical correlation between temperature, relative humidity and rainfall considered together and the number of N. linearis larvae per gram of faeces. Linear regression showed a correlation between the temperature and the percentage of sheep that passed M. capillaris. In general, the prevalence and intensity of infection of the sheep with N. linearis, M. capillaris and C. ocreatus larvae decrease when the temperature increases and increase when the relative humidity and rainfall increases.

Animals↗
PubMed2002

Early onset prostate cancer: predictors of clinical grade.

PURPOSE: Prostate cancer is typically a disease of elderly men and, therefore, it has not been well characterized in those affected at a young age. With the advent of serum prostate specific antigen testing, we are able to detect prostate cancer in young men even in the absence of symptoms. We studied a large group of early onset prostate cancer cases to illustrate the clinical presentation of men with early onset prostate cancer and to determine the effect of family history on Gleason grade as a reflection of prognosis. MATERIALS AND METHODS: All study participants were enrolled in the University of Michigan Prostate Cancer Genetics Project. Enrollment criterion of the Prostate Cancer Genetics Project includes a diagnosis of prostate cancer at age 55 years or younger. Descriptive statistics and logistic regression were used to characterize early onset prostate cancer and assess the associated prognostic factors. RESULTS: The study group was comprised of 257 men with prostate cancer diagnosed at age 55 years or younger. Median age at diagnosis was 51 years (range 34 to 55) and almost half of the participants reported a negative family history of prostate cancer. In logistic regression analysis having an affected father, an affected first-degree relative or an affected relative of any relation was each a statistically significant predictor of well differentiated (Gleason 6 or less) compared to moderately and poorly differentiated prostate cancer (Gleason 7-10) after adjusting for confounding variables. Men with an affected relative were nearly twice as likely to have well differentiated prostate cancer compared to men without affected relatives. CONCLUSIONS: Family history appears to predict the development of well differentiated tumors independently. In our study men with no family history of prostate cancer had higher grade tumors, which are associated with a more serious prognosis. Future studies of early onset prostate cancer should be directed toward identifying additional risk factors that may be relevant for men without a family history of the disease.

Adult↗
PubMed2001

Reliability and validity of the Child and Adolescent Trial for Cardiovascular Health (CATCH) Food Checklist: a self-report instrument to measure fat and sodium intake by middle school students.

OBJECTIVE: To develop a scoring algorithm and evaluate the reliability and validity of scores from the Child and Adolescent Trial for Cardiovascular Health (CATCH) Food Checklist (CFC) as measures of total fat, saturated fat, and sodium intake in middle school students. DESIGN: Randomized, controlled trial in which participants were assigned to 1 of 3 study protocols that varied the order of CFC and 24-hour dietary recall administration. Criterion outcomes were percent energy from total fat, percent energy from saturated fat, and sodium intake in milligrams. SUBJECTS/SETTING: A multiethnic sample (33% ethnic and racial minorities) of 365 seventh-grade students from 8 schools in 4 states. STATISTICAL ANALYSES: Multivariable regression models were used to calibrate the effects of individual food checklist items; bootstrap estimates were used for cross-validation; and kappa statistics, Pearson correlations, t tests, and effect sizes were employed to assess reliability and validity. RESULTS: The median same-day test-retest reliability kappa for the 40 individual CFC food items was 0.85. With respect to item validity, the median kappa statistic comparing student choices to those identified by staff dietitians was 0.54. Test-retest reliability coefficients ranged from 0.84 to 0.89 for CFC total nutrient scores. Correlations between CFC scores and 24-hour recall values were 0.36 for total fat, 0.36 for saturated fat, and 0.34 for sodium; CFC scores were consistent with hypothesized gender differences in nutrient intake. APPLICATIONS/CONCLUSIONS: The CFC is a reliable and valid tool for measuring fat, saturated fat, and sodium intake in middle school students. Its brevity and ease of administration make the CFC a cost-effective way to measure middle school students' previous day's intake of selected nutrients in school surveys and intervention studies.

Adolescent↗
PubMedDate not supplied

Field performance of current generation breath-alcohol simulators.

The between-run accuracy and reproducibility of vapor-alcohol control tests associated with quantitative evidential breath-alcohol testing in the field were evaluated. Control samples were generated at six separate sites with 34 degrees C TOXITEST II breath-alcohol simulators and analyzed by infrared spectrometry with Model 5000-D intoxilyzers in the recirculation mode. Control test results at target alcohol concentrations of 0.060, 0.080, 0.090, 0.100, 0.110, and 0.120 g/210 L (n = 779) were combined and analyzed by standard statistical methods. Results were correlated with target values, and the signed and absolute differences were calculated and analyzed. Data treatment included ANOVA, linear regression analysis, t statistics, and relative and cumulative frequency distributions of the differences. We found the performance of these current generation simulators in the field to be similarly satisfactory to that obtained in our laboratory evaluation. We further found that vapor-alcohol control samples generated with these devices conformed to established formal requirements and that they can serve as an effective quality assurance measure in evidential breath-alcohol analysis.

Breath Tests↗
PubMed1995

Evaluation of three types of support surfaces for preventing pressure ulcers in patients in a surgical intensive care unit.

Because critical care nurses recognize that many of their patients are at risk for pressure ulcer development, they provide them with support surfaces that can reduce this risk. Few reported studies, however, are available to help these nurses choose these surfaces wisely. This project was a new-product evaluation that compared the clinical effectiveness of three types of support surfaces: two dynamic mattress replacement surfaces and a static foam mattress replacement. Members of a convenience sample of 110 patients admitted to a surgical intensive care unit each used one of the three support surfaces. When each patient was placed on one of the three surfaces, the evaluators rated likelihood of pressure ulcer development (Braden Scale score) and assessed the skin for pressure ulcers. The evaluators repeated the Braden Scale score weekly and the skin assessment three times each week. Nine patients (8%), three patients on each support surface, acquired pressure ulcers. The log-rank test did not find a statistically significant difference between the three types of support surfaces with respect to the risk of pressure ulcer development. Stepwise Cox proportional hazards regression revealed a statistically significant relationship between the risk of developing a pressure ulcer, the averaged total Braden Scale score, and the averaged score for the sensory perception subscale of the Braden Scale. Although these three surfaces were comparable in effectiveness, they were not comparable in cost. Both dynamic mattress replacement surfaces cost approximately $2000 each, whereas the cost of the static foam mattress replacement was only $240 each. The results of this product evaluation should encourage other nurses to evaluate patient care products carefully before making recommendations.

Adolescent↗
PubMed1980

Multiple regression analysis predictor models in exotropia surgery.

We developed a statistical model based on multiple regression analysis from a sample population of 30 patients with intermittent exotropia who underwent bilateral recession of the lateral recti muscles. We also identified predictor variables, which accounted for most of the change in deviation per millimeter of surgery performed. The application of multiple regression analysis to the problem of exotropia may be limited by variation in predictor variables according to sample population, multicollinearity, measurement unreliability, and the unproven assumption that the preoperative calculation of effect per millimeter correlates well with postoperative clinical success. Controlled clinical trials are needed to determine the value of multiple regression analysis in exotropia surgery. Discriminant analysis may represent an alternative statistical technique with application to this particular problem.

Humans↗