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PubMed1988

Molecular shape of Lumbricus terrestris erythrocruorin studied by electron microscopy and image analysis.

The molecular structure of erythrocruorin (hemoglobin) from Lumbricus terrestris has been studied by electron microscopy of negatively stained particles. Over 1000 molecular projections were selected from a number of electron micrographs and were then classified by multivariate statistical image-processing techniques. The two main groups of top and side views were each subdivided into smaller classes with significantly different features. About half of the top-view projections exhibit perfect hexagonal symmetry at the current resolution of about 2.0 nm, while the other top views lack this symmetry, probably as a result of tilting of the molecules relative to the carbon support film. The side views were separated into two 'families', each associated with the two different stable side-view positions the molecules can take. From these narrow stable side-views, the two families of projections are, again, generated by tilting. The symmetry properties of the three non-tilted projections show that Lumbricus erythrocruorin has a pointgroup D6 (622) symmetry rather than D3 (32).

Animals↗
PubMed1990

Structure of ribosomes from Thermomyces lanuginosus by electron microscopy and image processing.

Multivariate statistical analysis and hierarchical ascendant classification techniques have been used to sort electron images of ribosomes from the thermophilic fungus Thermomyces lanuginosus into their characteristic views. Three predominant views were elucidated, called here overlap, non-overlap and top, showing reproducible detail approaching 1.8 nm resolution. The overlap and non-overlap forms of the fungal ribosomes appeared to be similar to those from the eubacterium Escherichia coli, despite differences in rRNA composition. The non-overlap projection predominated for the fungal complexes, suggesting different adsorption properties for ribosomes from the two species. Additionally, the top view has not been previously described for eubacteria. No major morphological differences could be detected between the fungal and eubacterial ribosomes at the resolution achieved in this study, suggesting a strong conservation of tertiary structure of this macromolecular complex despite the evolutionary gap between these two organisms.

Escherichia coli↗
PubMed1985

The risk of surgical treatment of tetralogy of Fallot: an appraisal.

The risk of surgical treatment of tetralogy of Fallot was analyzed with multivariate statistical techniques in a recent surgical series (1975-1983) of 159 corrected and 59 palliated patients. The overall mortality of correction was 12.6% and that of palliation was 15.3%. The significant and independent risk factors that increased the mortality of palliation were the use of a shunt other than the Blalock or its modifications (mostly Waterston) (P = 0.01), and very young age (P = 0.02). Risk factors that increased the mortality of correction were high left over right ventricular pressure ratio (P-RV/LV) (P = 0.02), persistent patency of the arterial duct (P = 0.02), other major associated lesions (P = 0.02), and the use of a transannular patch (P = 0.04). Cardioplegia significantly decreased the risk (P = 0.03). With present techniques, correction can be performed in favorable cases with a mortality approaching zero. Staged procedures neutralized the age related risk of correction, but Blalock shunts carried a mortality rate ranging from 9.5% at 1 month to 1.7% at 12 months of age. This was due to the lack of prostaglandins along with technical faults. Predicted two-stage mortality rates ranged in infants (less than 12 months) from 6.2 to 16% and compared favorably with our observed 27% mortality of primary correction. Our results show that the transannular patch becomes a fully expressed risk only in those patients with restrictive pulmonary arteries or isolated branch stenosis. This is because it decreases the force the right ventricle can generate in maintaining the cardiac output. The chances of survival, when compared with those of patients without transannular patch, are significantly less when the P-RV/LV is between 0.6 and 1.0. We therefore discuss the measures to decrease or neutralize this risk related to insertion of a transannular patch. Among the associated lesions, we discuss briefly the potential for residual right outflow tract stenosis, anomalous origin of the left anterior descending coronary artery and anomalous muscle bundle of the right ventricle.

Adolescent↗
PubMed1986

Neurometric evaluation of the cortical somatosensory evoked potential in acute incomplete spinal cord injuries.

The clinical application of evoked potentials has at times been criticized for its failure to provide an objective quantifiable assessment of the processing of sensory information and a reflection of nervous system integrity at least comparable in accuracy to other methods of assessment. The challenge is to quantify the SEP in a manner that accurately reflects the function of the somatosensory system. Therefore, neurometrics, an approach which emphasizes the transformation of neurophysiological data to a common metric of relative probability by reference to normative standards and the classification of critical features of data by multivariate statistics, was employed. The 3-part study involved the evaluation of the diagnostic, prognostic and localization functions of the cortical tibial SEP in patients with incomplete spinal cord injuries. Two neurometric indices which correlated well with concurrent and future neurological status were developed. The distributions of influence of dorsal columns and spino-thalamic tracts on the SEP were established.

Adult↗
PubMed1985

The use of historical controls in breast cancer. An assessment in three consecutive trials.

To evaluate the effectiveness of a new therapy some authors suggest the use of a retrospective control group, especially in cancer trials. In this article, by means of data collected in three consecutive randomized clinical trials on breast cancer performed at the Istituto Nazionale Tumori of Milan, the risks of a practice involving use of data from one trial as "historical controls" for the next one were investigated. The comparability between the baseline characteristics of different groups has been examined by resorting to univariate as well as multivariate statistical methods. The results of the final evaluation of the relative effectiveness of the treatments under study have also been investigated, using both randomized concurrent and historical controls. Although the eligibility criteria did not change, some differences between groups of consecutive trials were observed. The results attained by using historical control data, after adjusting for the differential composition in the baseline characteristics, made evident a biased conclusion in favor of the new treatment tested, which, in a historically controlled study, is always the last one. These results appear to be in agreement with those published by Sacks, Chalmers, and Smith (Am J Med 72:233-240, 1982).

Adult↗
PubMed1988

Analysis of air pollution plant exposure data: The soft independent modelling of class analogy (SIMCA) and partial least squares modelling with latent variable (PLS) approaches.

Air pollution plant exposure experiments sometimes involve registration of several plant variables (dependent variables) as a function of several treatment variables (independent variables). Both independent and dependent variables might be correlated, and the number of variables might exceed the number of observations. Analyzing one variable at a time gives a risk of spurious results. The multivariate statistical methods, soft independent modelling of class analogy (SIMCA) and partial least squares modelling with latent variables (PLS) allow all variables to be analyzed simultaneously. These methods are presented and applied to data from open-top chamber experiments with O3, SO2, and NO2 fumigation of three varieties of Lolium multiflorum Lam. The results demonstrate the dependence of the plant response to plant variety, plant age, climate, and pollutant dosages.

Journal Article↗
PubMed1991

Public knowledge of thalassemia in Greece and current concepts of the social status of the thalassemic patients.

Current concepts with regard to the social integration of the thalassemia patient worldwide require further evaluation. In this work we have investigated the concepts of the average citizen of continental Greece and Crete about the problem of thalassemia, his awareness of the basic characteristics of the disease and his attitudes towards some 'life-style' parameters of the thalassemic sufferer. We used the method of stratified random sampling and interviewed 3500 people aged 15-65 years. We carried out multivariate statistical analysis of responses to the items on thalassemia in relation to sex, age, educational level, place of residence and marital status. The results of this survey show that education was the factor with the greatest influence on the likelihood of being aware of thalassemia and of having accurate knowledge of the basic features of the disease. There was also a general effect of age with the highest awareness and the best knowledge being found in those aged 21-44 years, while place of residence was a significant factor for two items. The features known best were that thalassemia is non-infectious, that it calls for blood transfusion, and is inherited. Education had the strongest influence on the probability that a person holds the attitude that the sufferer from thalassemia can play a normal role in society as regards working and having a family, as well as generally living a normal life and, in the case of thalassemic children, playing and going to school. The attitude that thalassemics should work instead of receiving a state benefit depended on education, age and place of residence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Sociocultural factors associated with smoking behavior by Puerto Rican adolescents in Boston.

This study examined cigarette smoking among Puerto Rican adolescents in the Boston area in its sociocultural context by describing who uses cigarettes, and by identifying factors that encourage or discourage cigarette use. The study, conducted from 1986-87, used two approaches. The first was to survey 605 Puerto Rican households with adolescents 11-20 years old. Households were identified from a random sample of census blocks in five neighborhoods. In each household, interviews were completed with one adolescent and his or her female caretaker. The second approach was to conduct ethnographic interviews with 40 adolescents selected through a purposive sample of survey respondents from three of the study neighborhoods. Bivariate and multivariate statistical analyses were used to examine the relationships between smoking behavior and characteristics of the adolescents. The results of these analyses were examined in light of the ethnographic data. Overall, 13.7% reported smoking in the month preceding the interview. Smoking was most prevalent among males 17-20. Patterns of smoking were associated with teens' social networks. The Puerto Rican adolescents in this study were more likely to smoke when their friends and household members smoked, if they participated in recreational activities such as sports or unsupervised games, and if they were not in school. These effects varied according to the gender of the respondent.

Adolescent↗
PubMed1988

Quantitative evaluation of real-time ultrasound features of the breast.

Semi-quantitative diagnostic features were extracted by a visual analysis of the echographic images of selected cases of breast disease and the results stored in a computer database. The long term aim is to create an environment suitable for the use of multivariate statistical methods systematically to evaluate ultrasound interpretive criteria and diagnostic performance in relation to factors such as scanning instrumentation and other diagnostic techniques. Eventually it is hoped that it will be possible to generate a system for computer assisted diagnosis and training. The results of this pilot study serve to demonstrate the feasibility of the approach and a univariate analysis is used to provide a preliminary ranking of diagnostic features. Features found to be particularly valuable for distinguishing benign from malignant solid lesions were the regularity and definition of the edge of the tumour, the mobility of the tumour and measures of echo heterogeneity within and posterior to the tumour mass.

Breast↗
PubMed1986

Influence of psychological factors on postoperative pain, mood and analgesic requirements.

Previous research has indicated that postoperative pain, mood and analgesic requirements are influenced by diverse demographic and psychological variables. The data, however, are inconsistent and the extent of these influences has not been explored using multivariate statistical methods. In the present investigation patients scheduled for elective gallbladder surgery were examined for levels of pain, mood and analgesic needs, and the data were analyzed by using stratified stepwise multiple regression analysis. The results indicate that approximately half of the variability in the postoperative outcome measures could be predicted by a set of variables which include the patient's anxiety, extroversion, depression, educational level, previous chronic pain syndromes, and bias toward using medication. The implications of these results are discussed in relation to pain management strategies for surgical populations.

Adult↗
PubMed1990

Psychosocial correlates of temporomandibular joint pain and dysfunction.

This study examines psychological differences between temporomandibular joint pain and dysfunction (TMJPD) patients, pain controls, and healthy controls. Two hundred and two patients were classified, according to the diagnostic criteria of Eversole and Machado, as either myogenic facial pain (n = 42), internal derangement type I (n = 69), internal derangement type II (n = 85), or internal derangement type III (n = 6). Patients completed the Basic Personality Inventory, the Illness Behavior Questionnaire, the Multidimensional Health Locus of Control, the Perceived Stress Scale, and the Ways of Coping Checklist. Subjects also answered question pertaining to TMJPD symptomatology, including chronicity and severity. After conservative treatment with simple jaw exercise and ultrasound, patients were contacted again at 5 months to complete follow-up questionnaires similar to those previously completed. Comparison groups were comprised of 79 patients attending outpatient physiotherapy clinics for pain-related injuries not involving the temporomandibular joint and 71 pain-free, healthy students. Data were analyzed using multivariate statistics. The results indicate a significant relationship between pain intensity (and to some extent chronicity) and diverse measures of personality among the pain controls but not among the TMJPD patients. This calls into question the validity of assuming individual pain disorders are subsets of a larger, homogenous pain disorder population. TMJPD patients and pain controls score higher on hypochondriasis and anxiety than the pain-free controls but these elevations are not clinically significant. The elevations decrease to normal levels in response to a positive treatment outcome. There were no differences between the TMJPD patients and the pain controls on any of the measures. These results suggests that TMJPD patients do not appear to be significantly different from other pain patients or healthy controls in personality type, response to illness, attitudes towards health care, or ways of coping with stress.

Adult↗
PubMed1992

Automated 'pain drawing' analysis by computer-controlled, patient-interactive neurological stimulation system.

We have developed a new method for the collection and analysis of pain drawings, as part of a computer-controlled, patient-interactive system for use with implanted neurological stimulators. The system has been tested in 44 patients with permanently implanted spinal cord stimulators for the relief of chronic, intractable pain. Patients interact directly with the system, using a graphics tablet, to enter pain drawings and corresponding outlines of their perceptions of stimulation paresthesias, for different stimulating pulse parameters and electrode geometries. Image analysis software has been developed to examine these data quantitatively. This precludes the inter-rater inconsistencies reported for manual pain drawing scoring techniques. A highly significant correlation has been observed between patients' analog ratings of the overlap of pain by paresthesias and the results of our automated analysis of graphic data. This in turn has been found to correlate with clinical observations of pain relief. The contemporary implantable stimulation devices supported by our system permit non-invasive selection of stimulating anodes and cathodes from a linear array of 4 electrodes. The 50 possible electrode combinations have certain geometric features, which we have entered into a multivariate statistical analysis, to determine their relationship with the overlap of pain by paresthesias. One particular configuration (cathode(s) flanked by anode(s) above and below) is significantly better, by this measure, than all the alternatives. This is consistent with prior clinical observations that this configuration is favored by patients whose systems have been adjusted by conventional, manual methods. Pain drawing' entry and analysis by a computerized, patient-interactive system has been useful in this specialized setting and may have broader applications.

Adult↗
PubMed1988

The characterization of structural variations within a crystal field.

The technique of correlation averaging is refined by the use of multivariate statistical analysis and classification. The refined method can deal with the presence of structural variations within a crystal field. A low-dose image of a crotoxin crystal embedded in ice is used to demonstrate that crystallographic structural parameters characterizing the different areas of such a crystal with varying structure can be extracted rigorously and reproducibly.

Analysis of Variance↗
PubMedDate not supplied

Invariant classification of molecular views in electron micrographs.

Biological macromolecules can exhibit many different orientations in electron microscopical preparations. In particular in vitreous-ice-embedded specimens, the number of different views can be high. Existing techniques of analysis require the alignment of the molecular views relative to one or more reference images with cross-correlation ("matched filtering") techniques and are somewhat unsatisfactory because of the high noise level and the large number of different views in such images. We here propose a method in which first rotation-, translation- and mirror-invariant functions are derived from the large set of input images. These functions are subsequently classified automatically using multivariate statistical classification techniques. The different molecular views in the images can therewith be found without bias, provided that a statistically significant number of copies of the views are present in the data set. The basic ideas are exemplified with realistic model data.

Fourier Analysis↗
PubMed1984

The EORTC treatment of early stages of Hodgkin's disease: the role of radiotherapy.

Since 1964, the European Organisation for Research and Treatment of Cancer has conducted three subsequent clinical trials on clinical Stages (CS) I + II Hodgkin's disease (HD) in which 1059 patients have been entered. The first trial compared regional radiotherapy (RT) with mantle field or inverted Y, versus the same RT followed by a weekly injection of vinblastine for 2 years. The relapse free survival (RFS) and overall survival (S) were higher in patients treated by RT and chemotherapy (CT). This benefit, however, was significant only in patients with a mixed cellularity histologic type. The second trial compared the therapeutic efficacy of splenic irradiation versus splenectomy and found that in both arms, RFS and S were identical. Moreover, it was found that splenic involvement was correlated with an increased incidence of relapse in extranodal sites and in non irradiated lymphatic areas. In this trial, CT was given only to patients with poor histologic types, mixed cellularity or lymphocytic depletion. In the third trial, staging laparotomy was performed only to further delineate a good prognostic group which could be treated by RT alone. In this limited treatment group, there was no difference in RFS and S between mantle field and mantle field + para-aortic RT. In the extensive treatment group, total nodal irradiation (TNI) was compared with RT + MOPP. The RFS was slightly lower in the TNI arm, but there was no significant difference in S. The data of the 3 trials underline the importance of prognostic factors in the choice of optimal treatment and show that their significance depends upon the type of treatment. Multivariate statistical analyses showed that the main prognostic factors, which can help to identify the subsets of patients who can be treated by RT alone, are (1) systemic symptoms and elevated erythrocyte sedimentation rate (ESR), (2) the number of involved lymphatic areas, and (3) staging laparotomy. Extended RT (mantle + para-aortic + spleen treatment) gives satisfactory results in patients without systemic symptoms and/or elevated ESR and one or two involved sites, whereas TNI or combined modality treatment becomes mandatory for patients with 3 or more involved sites or splenic involvement and/or systemic symptoms. With proper adjustment of the irradiated volume, a very large proportion of CS I + II patients can be best treated by RT alone.

Adolescent↗
PubMed1994

Increased chronic bowel complications with split-course pelvic irradiation.

PURPOSE: To assess the possible impact of various treatment factors including split-course versus continuous course treatment on the incidence of chronic bowel complications in patients receiving adjuvant pelvic radiotherapy. METHODS AND MATERIALS: A retrospective review was performed of records of 153 patients treated with adjuvant external beam pelvic radiation therapy without brachytherapy for endometrial and colorectal carcinomas. Continuous course radiotherapy was administered in 91 patients (59%) and 62 patients (41%) received split course treatment with a planned 2 week mid-treatment break. Mean pelvic dose and daily fraction size were 51.4 and 1.71 Gray, respectively. Multiple patient and treatment variables were assessed for their possible relationship to chronic bowel complications. Univariate and multivariate statistical analyses were carried out. RESULTS: Twenty-seven patients (18%) developed chronic bowel complications at a median interval of 12 months after radiotherapy. Of all factors analyzed, only the use of split course technique was associated with a significantly higher rate of chronic bowel injury and decreased complication-free survival (p = 0.009). CONCLUSION: This study supports earlier suggestions that the use of split course rather than continuous course pelvic radiotherapy can increase late intestinal complication rates. Possible pathophysiologic mechanisms are discussed.

Adult↗
PubMed1984

Metabolic profiles of rats of different ages.

Urine samples from 6- to 31-month-old male Fischer F344 rats were analyzed using a high performance liquid chromatograph and a unique computer-based data analysis and quality control system in order to discover substances that could be used as markers in the aging process. Metabolic profiles of the organic acids from these urines yielded 42 peaks whose areas could be measured reliably. Of the 42 peaks, 10 were found by analysis of variance to vary significantly (p less than 0.05) with age. Rats from the four ages could also be distinguished using a multivariate statistic (discriminant analysis).

Aging↗
PubMed1993

An evaluation of the significance of areas of intense signal in the MR brain images of patients with multiple sclerosis.

This study evaluates the distribution of areas of intense signal (AIS) in 189 patients with multiple sclerosis (MS) and 83 patients presenting high-risk factors of cerebrovascular injuries. Two multivariate statistical analyses (multifactorial discriminant analysis and logistic regression analysis) with two AIS scores and several subpopulations of patients (according to age and/or the number of AIS) were tested. The results of these analyses were expressed with the usual screening test. The results obtained in this study even without the help of any clinical information are very promising, since they established that the specificity of MRI could be improved by using the distribution of the AIS in the various anatomical areas as a criterion. Five regions of the brain display were particularly significant in the discrimination between MS and non-MS patients: In decreasing order we found that the temporal, occipital, brain stem, and parietal regions were more specific with respect to the diagnosis of MS, while only the basal ganglia could account for non-MS patients. With multifactorial discriminant analysis and logistic regression analysis respectively, 78.9 (+/- 2.8)% and 85.1 (+/- 2.8)% of the patients were correctly classified by MRI. The results obtained on the main group were confirmed by a predictive test carried out on an other population of 40 patients, which produced similar results. The comparison between our method and Fazekas's imaging criteria showed a 20% improvement in favour of our approach and it is hoped that it will contribute to make the most of MRI as a tool for the diagnosis of MS.

Adolescent↗