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PubMed2005

Diagnosis of lung nodule using semivariogram and geometric measures in computerized tomography images.

This paper uses the geostatistical function - semivariogram and a set of 3D geometric measures - sphericity index, convexity index, extrinsic and intrinsic curvature index and surface type, to characterize lung nodules as malignant or benign in computerized tomography images. Based on a sample of 31 nodules, 25 benign and 6 malignant, these methods are first analyzed individually and then jointly, with techniques for classification and analysis (stepwise discriminant analysis, leave-one-out and ROC curve). We have concluded that the individual measures and their combinations produce good results in the diagnosis of lung nodules.

Discriminant Analysis↗
PubMed1991

Multivariate analysis of spect images with illustrations in Alzheimer's disease.

Modern neuroimaging techniques such as positron emission tomography and single photon emission computed tomography (SPECT) often generate datasets consisting of a large number of variables measured on a small number of subjects. In addition, the data contain large 'subject effects' which must be adjusted for in any statistical analysis. This paper illustrates the dangers inherent in naive univariate analysis and proceeds to demonstrate the application of multivariate methods such as Hotellings T2-test, canonical correlation analysis and discriminant analysis. The issues and statistical methods are illustrated using a dataset from a SPECT study of groups of normal control subjects and subjects with a clinical diagnosis of Alzheimer's disease.

Alzheimer Disease↗
PubMedDate not supplied

[A comparative analysis of the change in the EEG spectral characteristics of rats during the activation and suppression of the catecholaminergic systems].

To find EEG-markers of catecholaminergic activation shifts EEG power spectra of white rats were computed before and after intraperitoneal injections of propranolol, metaproterenol, haloperidol, amantadine, or isotonic sodium chloride solution. Differential spectral characteristics were undergone to factor analysis and discriminant analysis. Factors with similar structure for both catecholaminergic systems were revealed in EEG-reactions to mutually antagonistic injections and relatively specific factors as well. The leading factor of adrenotropic injections described the augmentation of the spectral power in the range of 9-16 Hz induced by propranolol and its reduction by metaproternol. Similar factor was also revealed in reactions to dopaminotropic injections with the smaller value of discriminant function coefficient. One more common feature of EEG-reactions to catecholaminergic disturbances was found to consist of the reciprocal narrow-band shifts in the theta- and delta-diapasons. The leading factor for the recognition of dopaminotropic disturbances described the increase of EEG power in the band of 19-30 Hz at activation and its reduction at suppression of the transmitter system.

Animals↗
PubMed2001

[Prospects for prognosis in cardiac surgery: experience from using discriminant linear analysis].

The authors evaluate the possibility of using the discriminant linear analysis in predicting the unfavourable outcomes at aortocoronary bypass. There were investigated 98 patients (the mean age 64.4 +/- 3.0 years) who underwent the surgical revascularization of myocardium in 1992-1997. 56 signs characterizing the demographic, clinical-and-instrumental and operational indices were analyzed. The obtained discriminant equation of operation outcome prediction included 15 signs. The operation for unstable angina, the cholesterol level and the patient's age were the most informative parameters. The total per cent of correct classification was 87.8%. According to the authors' experience the discriminant linear analysis is the informative method of multi-dimensional statistical analysis permitting to reveal the most significant signs that influence on the prognosis of surgical intervention.

Aged↗
PubMed1982

Plasma progesterone levels from oestrus through day 7 after A.I. in heifers carrying embryos with normal or deviating morphology.

Twenty-five dairy heifers, 11 repeat breeder and 14 virgin heifers, were used. Blood samples were taken twice a day (9 a.m. and 3 p.m.) from day of A.I. to 7 days later when embryo collection was made. One series of blood samples were taken from 16 heifers and two and three, respectively, from 6 and 3 heifers. Analysis of progesterone was performed by radioimmunoassay. The embryos were classified in 3 groups: normal blastocysts, morphological deviators, and degenerated embryos. Analysis of variance and a discriminant analysis was performed. The discriminant analysis was made to predict embryonic morphology, using daily progesterone values as predictors. No significant relationship between embryonic morphology and progesterone levels was found. The discriminant analysis showed that 64.9 % of progesterone curves were correctly classified, with individual groups ranging from 50 % (degenerated) to 76.5 % (normal embryos). It was concluded that abnormal embryonic development occurs with normal lateal function and that normal bovine embryo does not exhibit luteotrophic activity 7 days after mating.

Journal Article↗
PubMed1995

Predictive quantitative structure-activity relationships (QSAR) analysis of beta 3-adrenergic ligands.

A novel quantitative structure-activity relationships strategy was used to analyze seventeen beta-adrenergic ligands for which we had previously evaluated pharmacological properties in Chinese hamster ovary cells transfected with the human beta 1-, beta 2- or beta 3-adrenergic gene (Blin et al., 1993, Mol. Pharmacol., 44: 1094-1104). These ligands were classified into pharmacological activity categories in order to determine the extent to which molecular structural features may be involved in the selectivity of the interaction with the beta 3-AR, or to define molecular features and properties characteristic of a beta 3-AR high affinity ligand or of a potent beta 3-adrenergic agonist. Topological and physico-chemical molecular descriptors were obtained using a novel software combining calculations with multivariate statistical methods, such as principal component analysis and discriminant analysis. This study showed that beta 1/beta 2-antagonists beta 3-agonists could be differentiate from beta 1/beta 2/beta 3-agonists on the basis of their topological molecular descriptors weighted by partial atomic charge and lipophilicity logP values. Bulky lipophilic groups at the end of the alkylamine chain and an ethoxy function, extending the flexible portion of the molecule and modifying the electron density distribution, were requirements for selective agonism at the beta 3-site. Charge and logP weighted 2D-autocorrelation vectors were properties able to discriminate between classes of agonists in terms of their affinity, potency or intrinsic activity, thus emphasizing the part these molecular descriptors play in determining beta 3-adrenergic ligands. These results, in association with the powerful activity-prediction model evaluated in the test, provide a framework to rationalize the synthesis of new beta 3-AR specific compounds.

Adrenergic Agents↗
PubMed2004

Comparative analysis of dermatoglyphic traits in Hungarian and Gypsy populations.

We examined dermatoglyphic prints of children in 11 Hungarian and 5 Gypsy population samples (collected from 1,998 children). We compared Hungarian and Gypsy populations based on 22 finger and 24 palmar traits. In univariate comparisons the two ethnic groups differed significantly in half of the studied variables (9 finger and 14 palmar traits). We used several types of multivariate analyses of the studied traits to separate the population samples. Homogeneity analysis and discriminant analysis proved to be the most appropriate method to distinguish the populations, whereas a principal components analysis was less adequate. Multivariate analyses were conducted separately for both finger and palmar traits. Although the differences between the populations were more pronounced for palmar traits, in our study Hungarian and Gypsy populations showed the best separation when finger and palmar traits were combined for analysis, except in the principal components analysis. As expected, the Hungarian and Gypsy populations separated definitely in most statistical analyses; the main reason for this is the different origins of the two ethnic groups. The existence of the difference also shows that admixture between Hungarians and Gypsies has been small despite their living beside one another for several centuries.

Adolescent↗
PubMed2005

Changes in frontal plane dynamics and the loading response phase of the gait cycle are characteristic of severe knee osteoarthritis application of a multidimensional analysis technique.

BACKGROUND: Osteoarthritis of the knee is related to many correlated mechanical factors that can be measured with gait analysis. Gait analysis results in large data sets. The analysis of these data is difficult due to the correlated, multidimensional nature of the measures. METHODS: A multidimensional model that uses two multivariate statistical techniques, principal component analysis and discriminant analysis, was used to discriminate between the gait patterns of the normal subject group and the osteoarthritis subject group. Nine time varying gait measures and eight discrete measures were included in the analysis. All interrelationships between and within the measures were retained in the analysis. FINDINGS: The multidimensional analysis technique successfully separated the gait patterns of normal and knee osteoarthritis subjects with a misclassification error rate of <6%. The most discriminatory feature described a static and dynamic alignment factor. The second most discriminatory feature described a gait pattern change during the loading response phase of the gait cycle. INTERPRETATION: The interrelationships between gait measures and between the time instants of the gait cycle can provide insight into the mechanical mechanisms of pathologies such as knee osteoarthritis. These results suggest that changes in frontal plane loading and alignment and the loading response phase of the gait cycle are characteristic of severe knee osteoarthritis gait patterns. Subsequent investigations earlier in the disease process may suggest the importance of these factors to the progression of knee osteoarthritis.

Adaptation, Physiological↗
PubMed1991

TEXTINFO: a tool for automatic determination of patient clinical profiles using text analysis.

The clinical data contained in narrative patient documents is made available via grammatical and semantic processing. Retrievals from the resulting relational database tables are matched against a set of clinical descriptors to obtain clinical profiles of the patients in terms of the descriptors present in the documents. Discharge summaries of 57 Dept. of Digestive Surgery patients were processed in this manner. Factor analysis and discriminant analysis procedures were then applied, showing the profiles to be useful for diagnosis definitions (by establishing relations between diagnoses and clinical findings), for diagnosis assessment (by viewing the match between a definition and observed events recorded in a patient text), and potentially for outcome evaluation based on the classification abilities of clinical signs.

Databases, Factual↗
PubMed1993

Factors associated with use of safer sex practices among college freshmen.

The purpose of this exploratory study was to examine the relationship of knowledge of AIDS, misconceptions about AIDS, knowledge of safer sex practices, perceived susceptibility, and future time perspective to the practice of safer sex behaviors in 352 single, sexually active, college freshmen. Data were analyzed using stepwise multiple regression analysis and discriminant analysis. There were too few black females for analysis. Future time perspective explained the most variance in safer sex practices for black males. Knowledge of AIDS, perceived susceptibility, misconceptions about AIDS, knowledge of safer sex practices, and future time perspective did not explain a significant amount of variance in use of safer sex practices for either white males or females. However, perceived susceptibility and future time perspective differentiated sexually active from nonsexually active white males and females.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Finding cases of angle-closure glaucoma in clinic setting using a newly developed instrument.

PURPOSE: To validate the applicability of a newly developed, noncontact scanning peripheral anterior chamber depth analyzer (SPAC) for screening eyes at the risk of angle-closure glaucoma (ACG). SUBJECTS AND METHODS: All glaucoma patients who visited the University of Yamanashi Hospital from February through May 2003 were enrolled, except those with aphakic eye or pseudophakic eye. Of the 552 enrolled patients, 48 with ACG or narrow angles requiring laser iridotomy (LI) were categorized as patients with high-risk ACG eyes, and those with open angle were categorized as patients with control eyes. In all, 20 patients with ACG or narrow angles requiring prophylactic LI, who were followed up by an independent private ophthalmic clinic, were enrolled for threshold analysis. Nonophthalmologists measured anterior chamber depth and the averaged values of three measurements were employed for analysis. Threshold analysis and discriminant analysis were employed for determining the sensitivity and specificity of SPAC for diagnosing eyes with high-risk ACG. RESULTS: SPAC distinguished well the high-risk ACG eyes from the control eyes, and one of the most useful criteria for screening is as follows: any of the four measured points should exceed 95% confidence interval, and sensitivity and specificity should be 97.6 and 83.5%, respectively. CONCLUSION: SPAC is thought to be useful for detecting eyes at the risk of ACG by nonophthalmologists.

Anterior Chamber↗
PubMed1992

Why do elderly people seek professional home care? Methodologies compared.

In order to investigate which characteristics, besides physical limitations, of elderly people living at home contribute to the utilization of professional home care, a study was conducted in which 450 elderly people aged 55 and over, 123 with and 327 without professional home care, were interviewed. To obtain a selection for the interviews, a postal questionnaire, containing questions on functional status and care utilization, sent out to a random sample of the elderly people (55+) living at home (n = 2451), preceded the actual interviews. The oral interviews yielded the same information, plus an inventory of aspects of the mental status, the social network, the socio-economic status and the housing condition. Analysis was performed in three ways: bivariate analysis, logistic regression analysis and discriminant analysis. The bivariate analysis revealed that users of professional care were older, more often female and more often not married. Their social network was less extensive, as they received less informal care and lived alone more often. Besides they had more mental and financial problems. From the regression analysis it appeared that, in addition to the functional status, the amount of informal care and the household composition contributed to the utilization of professional home care. For the other characteristics inventoried, no independent association with the utilization of professional care could be established. With hindsight, it appeared that in this study long interviews hardly had additional value over postal questionnaires, in which the contribution of functional status and informal care to professional care was already discovered.

Aged↗
PubMed1991

Prediction of graduate dietetic internship appointments in Canada.

A statistical model of dietetic intern selection was developed from a profile of selection criteria that was obtained in a 1988 survey of Canadian graduate dietetic internship directors. The model was composed of four clusters of variables that resulted from the most frequently used selection criteria: academic performance, work experience, communication skills, and extracurricular activities. Data from a convenience sample of 39 dietetic intern applicants were analyzed, using principal components analysis and discriminant analysis, to test the model's power to predict success in obtaining an internship appointment. In descending order, the criteria with the greatest predictive powers were: academic performance; extracurricular activities; and supervisory, teaching, or instructing types of work experience. The model accounted for 41% of the differences between those who were successful and those who were not successful in obtaining internship appointments in 1989 and correctly classified 30 of 39 subjects. These results provide baseline data on the predictive power of some criteria used for selecting dietetic interns. These findings suggest the need for a replication study with a randomized national sample to crossvalidate the results obtained in this exploratory research.

Canada↗
PubMed2002

Important variable selection techniques with multiple solutions for medical information applications.

The purpose of this study is to utilize the strategy of multiple solutions with easily operated tools to make compatible and affordable trustworthy results. This strategy can satisfy general users in extracting specific knowledge (e.g. diagnosis, treatment, health education, hospital administration, etc.). Wide application is one of the key promoters of a successful medical information system. Risk factors of heart disease can be identified by important variable selection techniques. Four techniques, Chi-square test, correlation analysis, stepwise discriminant analysis, and decision trees, were used in this study. One must compile the results of the different methods to deal with specific research questions in a logical way. It is expected that this approach may reduce the uncertainties obtained from a single method. When applying the important index derived from the four different method results to several applications, all results have been confirmed by current medical knowledge or otherwise provide meaningful information. The prime purpose of this study is not disease diagnosis, but to enable the general health practitioner (medical doctor, hospital administrator, etc.) to formulate their hypothesis.

Case-Control Studies↗
PubMed2006

Chemometrics and visible-near infrared spectroscopic monitoring of red wine fermentation in a pilot scale.

The modern wine industry needs tools for process control and quality assessment in order to better manage fermentation or bottling processes. During wine fermentation it is important to measure both substrate and product concentrations (e.g. sugars, phenolic compounds), however, the analysis of these compounds by traditional means requires sample preparation and in some cases several steps of purification are needed. The combination of visible/near-infrared (Vis/NIR) spectroscopy and chemometrics potentially provides an ideal solution to accurately and rapidly monitor physical or chemical changes in wine during processing without the need for chemical analysis. The aim of this study was to assess the possibility of combining spectral and multivariate techniques, such as principal component analysis (PCA), discriminant partial least squares (DPLS), or linear discriminant analysis (LDA), to monitor time-related changes that occur during red wine fermentation. Samples (n = 652) were collected at various times from several pilot scale fermentations with grapes from either Cabernet Sauvignon or Shiraz varieties, over three vintages (2001-2003) and scanned using a monochromator instrument (Foss-NIRSystems 6500, Silver Spring, MD) in transmission mode (400-2,500 nm). PCA was used to demonstrate consistent progressive spectral changes that occur through the time course of the fermentation. LDA using PCA scores showed that regardless of variety or vintage, samples belonging to a particular time point in fermentation could be correctly classified. This study demonstrates the potential of Vis/NIR spectroscopy combined with chemometrics, as a tool for the rapid monitoring of red wine fermentation.

Biotechnology↗
PubMed2003

Orthotic comfort is related to kinematics, kinetics, and EMG in recreational runners.

PURPOSE: The purpose of this study was to determine the relationship between differences in comfort and changes in lower extremity kinematic and kinetic variables and muscle activity in response to foot orthoses. METHODS: Twenty-one recreational runners volunteered for this study. Three orthotic conditions (posting, custom-molding, and posting and custom-molding) were compared with a control (flat) insert. Lower extremity kinematic, kinetic, and EMG data were collected for 108 trials per subject and condition in nine sessions per subject for overground running at 4 m.s-1. Comfort for all orthotic conditions was assessed in each session using a visual analog scale. The statistical tests used included repeated measures ANOVA, linear regression analysis, and discriminant analysis (alpha = 0.05). RESULTS: Comfort ratings were significantly different between orthotic conditions and the control condition ([lower, upper] confidence limits; posting: [-3.1, -0.8]; molding: [0.4, 3.4]; and posting and molding: [-1.1, 1.9]); 34.9% of differences in comfort were explained by changes in 15 kinematic, kinetic, and EMG variables. The 15 kinematic, kinetic, and EMG variables that partially explained differences in comfort classified 75.0% of cases correctly to the corresponding orthotic condition. DISCUSSION: In general, comfort is an important and relevant feature of foot orthoses. Evaluations of foot orthoses using comfort do not only reflect subjective perceptions but also differences in functional biomechanical variables. Future research should focus on defining the relationship between comfort and biomechanical variables for material modifications of footwear, different modes of locomotion, and the general population.

Adult↗
PubMed2006

Prospects for clinical application of electronic-nose technology to early detection of Mycobacterium tuberculosis in culture and sputum.

Ziehl-Neelsen (ZN) staining for the diagnosis of tuberculosis (TB) is time-consuming and operator dependent and lacks sensitivity. A new method is urgently needed. We investigated the potential of an electronic nose (EN) (gas sensor array) comprising 14 conducting polymers to detect different Mycobacterium spp. and Pseudomonas aeruginosa in the headspaces of cultures, spiked sputa, and sputum samples from 330 culture-proven and human immunodeficiency virus-tested TB and non-TB patients. The data were analyzed using principal-component analysis, discriminant function analysis, and artificial neural networks. The EN differentiated between different Mycobacterium spp. and between mycobacteria and other lung pathogens both in culture and in spiked sputum samples. The detection limit in culture and spiked sputa was found to be 1 x 10(4) mycobacteria ml(-1). After training of the neural network with 196 sputum samples, 134 samples (55 M. tuberculosis culture-positive samples and 79 culture-negative samples) were used to challenge the model. The EN correctly predicted 89% of culture-positive patients; the six false negatives were the four ZN-negative and two ZN-positive patients. The specificity and sensitivity of the described method were 91% and 89%, respectively, compared to culture. At present, the reasons for the false negatives and false positives are unknown, but they could well be due to the nonoptimized system used here. This study has shown the ability of an electronic nose to detect M. tuberculosis in clinical specimens and opens the way to making this method a rapid and automated system for the early diagnosis of respiratory infections.

Biosensing Techniques↗
PubMed2001

Predictors of acquiring a nosocomial bloodstream infection on extracorporeal membrane oxygenation.

PURPOSE: The aim of this study was to identify independent predictors of acquiring a nosocomial bloodstream infection (BSI) during extracorporeal membrane oxygenation (ECMO). METHODS: This retrospective cohort consisted of 202 neonates treated with ECMO from 1989 to 1998 at the author' institution. Data collected included patient demographics, primary and secondary diagnoses, white blood cell counts, antibiotic usage, presence of central lines, operative procedures, and outcome. Surveillance blood cultures were drawn daily from the circuit using sterile technique to identify acquired pathogens. Statistical analyses included logistic regression, Cox proportional regression analysis, and discriminate analysis. RESULTS: There were 1,245 blood cultures drawn on 202 patients (6.2 cultures per patient), and a nosocomial BSI was identified in 7 patients (3.4%) during this 10-year span. These were infections that were neither present nor incubating on admission. Pre-ECMO diagnoses of patients who had a nosocomial BSI while on bypass included group B beta-hemolytic streptococcal sepsis (n = 2), herpes simplex viral sepsis (n = 1), congenital diaphragmatic hernia (n = 2), persistent pulmonary hypertension (n = 1), and congenital heart disease (n = 1). The median time on ECMO before obtaining a positive culture was 390 hours. The infectious agents responsible for these BSIs included Staphylococcus epidermidis (n = 5), Staphylococcus aureus (n = 1), and Escherichia coli (n = 1). The major factor associated with acquiring a nosocomial BSI on ECMO was the duration of bypass (391 v 141 hours, P =.002). Additionally, patients in the BSI group were more likely to have had an arterial catheter in place (16 v 7 days, P =.009) and to have received more screening blood cultures (16 v 6 cultures, P < 001). White blood cell counts, absolute neutrophil counts, and immature/total (I/T) ratios were not useful in predicting a nosocomial BSI. Of the 31 patients who required ECMO for more than 10 days, 7 (23%) had a positive blood culture, and 5 of these 7 infants (71%) died (P =.03). CONCLUSIONS: The only predictor of acquiring a nosocomial BSI on ECMO was the duration of support for greater than 10 days. Because classical predictors of infection are unreliable while the patient is on ECMO, the authors suggest that obtaining daily surveillance blood cultures beginning on the tenth day should be performed with prolonged ECMO courses. The authors confirmed previous reports of the association between a prolonged ECMO course and a high mortality rate. However, the authors speculate that, in actuality, the primary diagnosis leads to the prolonged course of support and is the major factor in the infant' demise.

Antibiotic Prophylaxis↗