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PubMed1999

Dimensional assessment of personality pathology in patients with eating disorders.

This study examined patients with eating disorders on personality pathology using a dimensional method. Female subjects who met DSM-IV diagnostic criteria for eating disorder (n = 136) were evaluated and compared to an age-controlled general population sample (n = 68). We assessed 18 features of personality disorder with the Dimensional Assessment of Personality Pathology - Basic Questionnaire (DAPP-BQ). Factor analysis and cluster analysis were used to derive three clusters of patients. A five-factor solution was obtained with limited intercorrelation between factors. Cluster analysis produced three clusters with the following characteristics: Cluster 1 members (constituting 49.3% of the sample and labelled 'rigid') had higher mean scores on factors denoting compulsivity and interpersonal difficulties; Cluster 2 (18.4% of the sample) showed highest scores in factors denoting psychopathy, neuroticism and impulsive features, and appeared to constitute a borderline psychopathology group; Cluster 3 (32.4% of the sample) was characterized by few differences in personality pathology in comparison to the normal population sample. Cluster membership was associated with DSM-IV diagnosis -- a large proportion of patients with anorexia nervosa were members of Cluster 1. An empirical classification of eating-disordered patients derived from dimensional assessment of personality pathology identified three groups with clinical relevance.

Adolescent↗

PubMed1997

Multivariate methods for clustered ordinal data with applications to survival analysis.

Clustered data are the rule in many clinical specialties such as ophthalmology. Methods have been developed for the treatment of clustered continuous or binary outcome data. Less attention has been given to ordinal outcomes which occur frequently in ophthalmology. For example, grading systems of cataract and diabetic retinopathy are commonly used where a photograph is graded by comparison with a series of reference photographs of increasing severity. Some commonly used methods for the analysis of ordered categorical data include the proportional odds and continuation ratio models. It is difficult, however, to incorporate clustering effects into these models. Instead, for clusters of size two, we propose a generalization of the adjacent category model given by log[Pr(i + 1,j)/Pr(i,j)] = ui + (j - 1) lambda + beta' x, where Pr(i,j) denotes the probability that the right (left) eye has grade i(j), x is a vector of (person or eye-specific) covariates for the right eye, u and beta are vectors of location and covariate parameters and lambda is a clustering parameter. Based on this model, and a similar model interchanging the role of i and j, we derived a closed-form expression for Pr(i,j) as a function of u, lambda and beta and use Newton-Raphson method to maximize the likelihood. An extension of the method allows for extra agreement along the diagonal and is then a generalization of the agreement plus linear-by-linear association model proposed by Agresti in the setting of no covariates. We apply these methods to a data set of 43 diabetic subjects from the Harvard Clinical Cataract Research Center, where cortical cataract grade was the outcome. We also extend this methodology to a survival setting, where both censored and uncensored outcomes are available for individual cluster members, and one wishes to take clustering into account. We apply the survival analysis model to a data set of 1807 children (two ears per child) in the greater Boston area, who were followed for the development of otitis media over the first year of life.

Boston↗

PubMed2003

Iteration as programmed event during polyketide assembly; molecular analysis of the aureothin biosynthesis gene cluster.

Analysis of the type I modular polyketide synthase (PKS) involved in the biosynthesis of the rare nitroaryl polyketide metabolite aureothin (aur) from Streptomyces thioluteus HKI-227 has revealed only four modules to catalyze the five polyketide chain extensions required. By heterologous expression of the aur PKS cluster, direct evidence was obtained that these modules were sufficient to support aureothin biosynthesis. It appears that one module catalyzes two successive cycles of chain extension, one of the first examples of a PKS in which such iteration or "stuttering" is required to produce the normal polyketide product. In addition, lack of a specified loading domain implicates a novel PKS priming mechanism involving the unique p-nitrobenzoate starter unit. The 27 kb aur gene cluster also encodes a novel N-oxidase, which may represent the first member of a new family of such enzymes.

Binding Sites↗

PubMed2001

Genome-wide approaches for identifying interacting susceptibility regions for asthma.

A genome-wide correlation analysis and cluster analysis were utilized to determine chromosomal regions that had similar nonparametric linkage scores across families in order to locate interacting susceptibility loci for asthma. Conditional analysis was performed to detect any increase in lod score over baseline. Eight of the strongest 5% of the correlations in the German and CSGA asthma data sets occurred in both data sets. The strongest positive correlations found in both data sets were between the 200 cM region on chromosome 2 with chromosome 12 at 90-120 cM (r = 0.26) and also with chromosome 6 at 40-70 cM (r = 0.24). While the cluster analysis did not find any regions that clustered across data sets, this method did detect clustering in regions that have been previously linked to asthma.

Adult↗

PubMed2003

Single-cell microarray analysis in hippocampus CA1: demonstration and validation of cellular heterogeneity.

Laser capture microdissection in combination with microarrays allows for the expression analysis of thousands of genes in selected cells. Here we describe single-cell gene expression profiling of CA1 neurons in the rat hippocampus using a combination of laser capture, T7 RNA amplification, and cDNA microarray analysis. Subsequent cluster analysis of the microarray data identified two different cell types: pyramidal neurons and an interneuron. Cluster analysis also revealed differences among the pyramidal neurons, indicating that even a single cell type in vivo is not a homogeneous population of cells at the gene expression level. Microarray data were confirmed by quantitative RT-PCR and in situ hybridization. We also report on the reproducibility and sensitivity of this combination of methods. Single-cell gene expression profiling offers a powerful tool to tackle the complexity of the mammalian brain.

Animals↗

PubMed2005

Chemometrics methods for the investigation of methylmercury and total mercury contamination in mollusks samples collected from coastal sites along the Chinese Bohai Sea.

The development and application of chemometrics methods, principal component analysis (PCA), cluster analysis and correlation analysis for the determination of methylmercury (MeHg) and total mecury (HgT) in gastropod and bivalve species collected from eight coastal sites along the Chinese Bohai Sea are described. HgT is directly determined by atomic fluorescence spectrometry (AFS), while MeHg is measured by a laboratory established high performance liquid chromatography-atomic fluorescence spectrometry system (HPLC-AFS). One-way ANOVA and cluster analysis indicated that the bioaccumulation of Rap to accumulate Hg was significantly (P<0.05) different from other mollusks. Correlation analysis shows that there is linear relationship between MeHg and HgT in mollusks samples collected from coastal sites along the Chinese Bohai Sea, while in mollusks samples collected from Hongqiao market in Beijing City, there is not any linear relationship.

Analysis of Variance↗

PubMed2006

Aggregation of health behaviors among fourth graders in northern Taiwan.

PURPOSE: To investigate the aggregation of health behaviors among fourth graders in northern Taiwan. METHODS: This study conducted an analysis of data collected from the 2001 Child and Adolescent Behaviors in Long-term Evolution (CABLE) project, which included a sample of 2075 fourth grade students. Factor analysis and cluster analysis were used to investigate the aggregation patterns. RESULTS: After factor analysis, we found that the 18 health behaviors could be grouped under five factors. These five factors were named: healthy behavior, rule-breaking behavior, substance use behavior, violent behavior, and pleasure-seeking behavior, according to the characteristics of the various health behaviors grouped under each of them. Each study subject was assigned points for each of these five factors and then cluster analysis was used to divide the subjects into four different clusters. The names of these clusters and the percentage of subjects within them were as follows: healthy group (43.47%), violent group (29.11%), pleasure-seeking group (22.55%), and rebellious group (4.87%). CONCLUSIONS: A total of 56.53% of the study sample were grouped under unhealthy groups (violent group, pleasure-seeking group and rebellious group), which indicates that already more than half of the students had lifestyles that put their health at risk. It was suggested that health and educational organizations need to place importance on behavioral problems in children and adopt early prevention measures.

Alcohol Drinking↗

PubMed1999

An analysis of subjective complaints in a population living in a methylmercury-polluted area.

The aim of this study is to document subjective complaints, to analyze the structure of a population living in a methylmercury-polluted area, and to investigate the relationship between the subjective complaints and methylmercury pollution. A total of 1304 adults in the polluted area, who were living in the methylmercury-polluted area near Minamata City in Kumamoto Prefecture, Japan, and 446 age-matched adults in a nonpolluted area were interviewed. Comparison of prevalence, factor analysis, and cluster analysis were conducted using data drawn from a questionnaire survey about 64 subjective complaints. The population in the polluted area had more various complaints than that living in the nonpolluted area. The factor analysis proposed four factors: nonspecific, sensory, arthritic, and muscular. Each of the four factor scores was significantly higher in the population in the polluted area. Subjects who had more complaints were classified into three clusters using cluster analysis. It is possible that not only neurological subjective complaints but also nonspecific complaints of the population in the polluted area might be influenced by past methylmercury exposure.

Adult↗

PubMed2006

Further analysis of the human spontaneous eye blink rate by a cluster analysis-based approach to categorize individuals with 'normal' versus 'frequent' eye blink activity.

PURPOSE: To further analyze the possible causes of variability in spontaneous eye blink activity in apparently healthy humans. METHODS: One hundred men, aged between 23 and 57 years and with no significant eye disease, were questioned on the number of ocular symptoms they experienced (one, two, three, and so forth). Five-minute video recordings were made of the eyes in primary gaze and in silence between 11:00 and 17:00 hours. The spontaneous eye blink rate (SEBR) and palpebral aperture features were assessed from the video recordings. The central corneal threshold touch sensitivity was then assessed with a Cochet-Bonnet aesthesiometer. RESULTS: The average SEBR was 13.8 +/- 9.7 blinks per minute (range, 2.8-48 blinks per minute), but the distribution was heterogeneous and skewed to higher values. The SEBR was not obviously dependent on the time of day that the recordings were made, on the number of mild symptoms that the subjects reported, or on the central corneal sensitivity (P> or =0.6). Analysis of SEBR in relation to age showed a possible weak association (P=0.082, r = 0.175), but SEBR showed absolutely no correlation with palpebral aperture height (P=0.546). A hierarchic cluster analysis clearly resolved the distribution of SEBR values into two distinct groups (P<0.001, F ratio = 222). CONCLUSIONS: Spontaneous eye blink activity can be rather different between healthy individuals, even under a single experimental condition. These differences do not appear to be caused by the time of day, mild symptoms, corneal sensitivity, age, or palpebral aperture features. In line with previous metaanalyses, it is therefore proposed that individuals could be grouped as to whether they have "normal" eye blink activity or be classified as having "frequent" eye blink activity. The latter group would include those who had an SEBR greater than 20 blinks per minute when assessed in primary eye gaze and in silence.

Adult↗

PubMed2006

Dietary patterns in the Southampton Women's Survey.

OBJECTIVE: Dietary pattern analysis is receiving increasing attention as a means of summarizing the multidimensional nature of dietary data. This research aims to compare principal component analysis (PCA) and cluster analysis using dietary data collected from young women in the UK. DESIGN: Diet was assessed using a 100-item interviewer-administered food frequency questionnaire. PCA and cluster analysis were used to examine dietary patterns. SETTING: Southampton, UK. SUBJECTS: A total of 6125 non-pregnant women aged 20-34 years. RESULTS: PCA identified two important patterns: a 'prudent' diet and a 'high-energy' diet. Cluster analysis defined two clusters, a 'more healthy' and a 'less healthy' cluster. There was a strong association between the prudent diet score and the two clusters, such that the mean prudent diet score in the less healthy cluster was -0.73 standard deviations and in the more healthy cluster was +0.83 standard deviations; the difference in the high-energy diet score between the two clusters was considerably smaller. CONCLUSIONS: Both approaches revealed a similar dietary pattern. The continuous nature of the outcome of PCA was considered to be advantageous compared with the dichotomy identified using cluster analysis. SPONSORSHIP: The study was funded by the Dunhill Medical Trust, the University of Southampton and the Medical Research Council.

Adult↗

PubMed1992

Classification of nonspecific low back pain. I. Psychological involvement in low back pain. A clinical, descriptive approach.

An unselected sample of outpatient subjects (n = 330) with localized nonspecific low back pain (LBP) was studied. Investigation consisted of clinical assessment, physical examination, and psychiatric interview based on the DSM-III classification. A psychiatric disorder, according to the DSM-III criteria (axis I) was found in 41% of the subjects. Multiple correspondence analysis and cluster analysis were used to objectively identify clinical subtypes without preconceived theoretical models. Correspondence analyses suggested the existence of a 'psychological pain' syndrome consisting of several of the following symptoms: diffuse back pain, impossibility to assess intensity of pain on a pain scale, aggravation of pain by changing climate, by domestic activities or by psychological factors and dysesthesias in the back. Cluster analysis provided support for a four-group classification of low back pain, which may be interpreted through the relationships between psychological disturbances and the LBP clinical features. The results call for further investigation of the complex relationship between psychological disturbances and back pain. However, clinicians must be aware of the interest of a minimal psychiatric assessment in low back pain patients: psychiatric disorders frequently appear in these patients and an appropriate treatment of the psychiatric syndrome may reduce back pain.

Adolescent↗

PubMed2002

[The naphtha composing characteristics of geoherbs of Atractylodes lancea].

OBJECTIVE: To find the chemical diversity and characteristics of A. lancea on two levels--individuals and populations, and to discover the chemical essentials for forming geoherbs. METHOD: 47 rhizomes of A. lancea were collected in 7 populations, and 6 naphtha components (1. elemol, 2. hinesol, 3. beta-eudesmol, 4. atractylone, 5. atractylodin, 6. atractylenolid I) in the rhizomes were determined by GC-MS combination. Principal Component Analysis and Cluster Analysis were carried out by SPSS. RESULT: Cluster Analysis of the 6 main components indicated that the chemical components of geoherbs were different from those of the non-geonerbs of A. lancea. Other analysis showed as follows: 1. The general oil of geoberbs were lower than that of non-geoherbs(P < 0.01), but components yielding more than 1% (% of the total oil) were more than non-geoherbs(P < 0.01); 2. Hinesol mixing beta-eudesmol was more in non-geoherbs, which atractylodin mixing atractylone was more in geoherbs(P < 0.001); 3. Principal Component Analysis implied that atractylone was the most important component to discriminate geoherbs and non-geoherbs of A. Lancea. CONCLUSION: The naphtha composing characteristics of geoherbs was the special proportionment sale, viz. atractylone: hinesol: beta-eudesmol: atractylodin being(0.70~2.00):(0.04~0.35):(0.09~0.40):1.

Atractylodes↗

PubMed2006

An exploration of the relationship between academic and experiential learning approaches in vocational education.

BACKGROUND: Research on individual learning approaches (or learning styles) is split in two traditions, one of which is biased towards academic learning, and the other towards learning from direct experience. AIMS: In the reported study, the two traditions are linked by investigating the relationships between school-based (academic) and work-based (experiential) learning approaches of students in vocational education programs. SAMPLES: Participants were 899 students of a Dutch school for secondary vocational education; 758 provided data on school-based learning, and 407 provided data on work-based learning, resulting in an overlap of 266 students from whom data were obtained on learning in both settings. METHODS: Learning approaches in school and work settings were measured with questionnaires. Using factor analysis and cluster analysis, items and students were grouped, both with respect to school- and work-based learning. RESULTS: The study identified two academic learning dimensions (constructive learning and reproductive learning), and three experiential learning dimensions (analysis, initiative, and immersion). Construction and analysis were correlated positively, and reproduction and initiative negatively. Cluster analysis resulted in the identification of three school-based learning orientations and three work-based learning orientations. The relation between the two types of learning orientations, expressed in Cramér's V, appeared to be weak. CONCLUSIONS: It is concluded that learning approaches are relatively context specific, which implies that neither theoretical tradition can claim general applicability.

Educational Status↗

PubMed2003

[Quality of life and well-being of elderly people: an exploratory study in the Portuguese population].

OBJECTIVES: To characterize elderly people's perception of quality of life and well-being. METHODS: A sample of 1,665 elderly aged 75 years or more living in 13 districts in Portugal were studied. Of them, 311 subjects were excluded because they were not able to convey their opinions. The EASYcare (Elderly Assessment System) was used to collect data from 1,354 (81.3%) of 1,665 subjects. Statistical analysis was based on principal components analysis and cluster analysis. RESULTS: EASYcare's showed to have good psychometric proprieties (Cronbach a =0.92). The principal component analysis identified 4 factors: mobility, communication competencies, well-being and daily living activities. Cluster analysis showed 4 groups of elderly people: autonomous (62.8%), almost autonomous (8.5%), almost dependent (4.3%) and dependent (3.2%). CONCLUSIONS: Quality of life for most of the elderly is quite positive, and only a small group presents problems related to severe cognitive impairment or some degree of dependence.

Activities of Daily Living↗

PubMed1995

Comparative behavioural and neurochemical studies with a psychomotor stimulant, an hallucinogen and 3,4-methylenedioxy analogues of amphetamine.

Spontaneous behaviours were assessed in freely moving rats after treatment with equimolar doses of drugs that share a basic amphetamine structure. The drugs used included a psychomotor stimulant [(+)-amphetamine (AMPH)], an hallucinogen [para-methoxyamphetamine (PMA)] and the entactogens 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDE). A detailed analysis of the frequency and duration of 30 different behaviours and the temporal organization of the behaviours was conducted in addition to measuring motor activity with an automated device. Levels of the biogenic amines and their acid metabolites in discrete brain regions and brain drug levels were also obtained. The automated motor activity measures discriminated among entactogens, the stimulant and the hallucinogen, but failed to distinguish between the hallucinogen and vehicle. Principal components analysis and cluster analysis of the frequencies and durations of the behaviours did not improve the classification of the drugs over the automated motor activity measures. Only the cluster analysis of the transitions between individual behaviours succeeded in differentiating the drug classes from each other and from vehicle treatment. All the behavioural measures classified one entactogen (MDE) as an hallucinogen. Cortical 5-hydroxytryptamine (5-HT) measures grouped MDE with the other entactogens but did not distinguish AMPH from vehicle. However, striatal dopamine measures differentiated AMPH from vehicle treatment. Variations in the durations of behavioural effects across drugs were associated with large differences in drug levels 3 h after injection. Although the neurochemical data provided a classification system that most closely parallels human subjective effects of these drugs, both the neurochemical and the behavioural measures supported the existence of an entactogen class distinct from a psychomotor stimulant and an hallucinogen.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2005

Neural net applied to anthropological material: a methodical study on the human nasal skeleton.

A new information processing method, an artificial neural net, was applied to characterise the variability of anthropological features of the human nasal skeleton. The aim was to find different types of nasal skeletons. A neural net with 15*15 nodes was trained by 17 standard anthropological parameters taken from 184 skulls of the Aachen collection. The trained neural net delivers its classification in a two-dimensional map. Different types of noses were locally separated within the map. Rare and frequent types may be distinguished after one passage of the complete collection through the net. Statistical descriptive analysis, hierarchical cluster analysis, and discriminant analysis were applied to the same data set. These parallel applications allowed comparison of the new approach to the more traditional ones. In general the classification by the neural net is in correspondence with cluster analysis and discriminant analysis. However, it goes beyond these classifications because of the possibility of differentiating the types in multi-dimensional dependencies. Furthermore, places in the map are kept blank for intermediate forms, which may be theoretically expected, but were not included in the training set. In conclusion, the application of a neural network is a suitable method for investigating large collections of biological material. The gained classification may be helpful in anatomy and anthropology as well as in forensic medicine. It may be used to characterise the peculiarity of a whole set as well as to find particular cases within the set.

Adult↗

PubMed2004

Utility of International Classification of Functioning, Disability and Health's participation dimension in assigning ICF codes to items from extant rating instruments.

OBJECTIVES: Firstly to investigate the utility of the International Classification of Functioning, Disability and Health's (ICF's) participation dimension when items from extant questionnaires focusing on participation were assigned to ICF codes on an item-by-item basis; and, secondly, to conduct a preliminary investigation of the theoretical assumption expressed in ICF that ICF's environment component interacts with body function and participation components. DESIGN: A person-based, descriptive study. SUBJECTS: The sample comprised students with disabilities (n = 448), their parents/relatives (n = 414), their teachers/managers (n = 418) and special education consultants (n = 110). METHODS: Items from original surveys were used. Participation of students with disabilities: a survey of participation in school activities, The Arc's Self-Determination Scale, Perceived interaction-questionnaire, Environments survey, The Abilities Index. Data were analysed with the help of ANOVA, Scheffé pair-wise comparisons, correlation analysis and cluster analysis. RESULTS: The study partly confirmed the utility of ICF participation dimension in assigning codes to items from extant instruments. Moderate statistical correlations between participation chapters and between items from different ICF dimensions were found. Cluster analysis resulted in groups with participation patterns not related to type of disability. CONCLUSION: Items from extant instruments can be assigned to ICF participation codes, but further item analyses and a more extensive questionnaire base are needed.

Activities of Daily Living↗

PubMed1991

Membrane fatty acids as phenotypic markers in the polyphasic taxonomy of methylotrophs within the Proteobacteria.

A polyphasic approach to bacterial taxonomy attempts to integrate phylogenetic relationships with phenotypic marker analysis. This study describes the application of membrane fatty acids as a phenotypic marker for methylotrophs. Detailed phospholipid, ester-linked fatty acid (PLFA) profiles are reported for 17 methylotrophic eubacterial strains. These profiles included verification of double bond positions and geometries, both critical features for this analysis. Multivariate cluster analysis was used to indicate groupings of these strains along with literature values of both methylotrophs and non-methylotrophs based on the PLFA phenotype. Like many phenotypic characteristics, PLFA profiles were influenced by environmental conditions. The instabilities displayed, however, were predictable from physiological studies including increased trans/cis and cyclopropyl/cis ratios. Cluster analysis of PLFA profiles generated by separate investigators with different culture conditions indicated reproducibility by strain and species. The PLFA phenotype relationships compare favourably with phylogenetic associations based on 16S rRNA data for methylotrophs and will continue to be a valuable phenotypic marker for Proteobacteria taxonomy.

Cell Membrane↗