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At least 811 records · Page 45Linked to original sources
PubMed2003

Nuclear chromatin texture in rectal cancer. Relationship to tumor stage.

OBJECTIVE: To characterize, by morphometric and chromatin texture analysis, a series of rectal carcinomas classified according to Dukes staging. STUDY DESIGN: High-resolution imagery of 6,001 nuclei from 51 specimens of rectal carcinoma and 22 specimens of normal rectal tissue was digitally recorded. A set of 93 features descriptive of the spatial and statistical distribution of nuclear chromatin was computed for each nucleus to form a characteristic signature. RESULTS: Rectal carcinomas were significantly different from normal rectum in their digital signature. Eleven karyometric features, such as nuclear area and total optical density, were clearly different between the groups, with significant differences found in analysis of 8 of those features. The most distinctive pattern in lesion signatures in comparison with normal rectal tissue was observed at Dukes' stage D. However, the highest average signature values were seen at Dukes' stage B. The lesion signatures and total optical density observed in cancer specimens deviated markedly from values in the normal group. CONCLUSION: Chromatin texture signature proved to be a useful method of identifying and characterizing nuclear differences between rectal carcinoma and normal rectal tissue.

Adenocarcinoma↗
PubMed2003

Nuclear chromatin texture in rectal carcinoma. Prognostic value.

OBJECTIVE: To investigate the prognostic value of nuclear features in rectal carcinoma. STUDY DESIGN: High-resolution imagery of 3,635 nuclei from 51 patients operated on for rectal cancer at various Dukes' stages was digitally recorded. A set of 93 features descriptive of the spatial and statistical distribution of nuclear chromatin was computed for each nucleus to derive a digital signature. Karyometric features were analyzed for correlation with progression of disease and death. RESULTS: Multivariate analysis of main karyometric features in comparison with cancer staging demonstrated that total optical density and clumpness, as well as average nuclear signature, had significant prognostic value in predicting cancer-related death. CONCLUSION: Digital signature seems to have a role as prognostic factor in rectal cancer. The method could be a useful parameter in deciding whether to perform adjuvant therapy in particular subgroups of patients, independently of tumor staging. However, these observations need to be substantiated with additional studies, including larger numbers of patients.

Adult↗
PubMed1992

[Jackknife and bootstrap].

The jackknife and the bootstrap are two non parametric methods which provide estimates- of the bias and the variance of an estimator, without any assumption about its statistical distribution. The jackknife is based on the observation of the estimator for subsamples, generally of size n-1, obtained from the original sample. The bootstrap is based on the observation of the estimator on size n samples drawn from the original sample. The two methods are presented, their principle is illustrated through their application to simple examples and to more complex epidemiological problems.

Bias↗
PubMedDate not supplied

[Approach to the study of suicide in the essays of Enrico Morselli (1879) and in the successive hypotheses of Durkheim and Freud].

Scientific investigations on suicide began at the beginning of the XIX century. The aim of such investigations was the evaluation of the epidemiological and statistical distribution of the phenomenon in order to set up preventive intervention, as well as the establishment of the psychological and psychopathological characteristics of the subjects choosing this solution to their life. E. Morselli's work on the matter (1879) can be considered the main Italian contribution to the discussion that was troubling and antagonizing the most competent authors in all the civil world from the half a century and it was regarded in due consideration by his contemporaries too. The second author taken into consideration is E. Durkheim, whose monograph issued twenty years later presents elements having such originality and accuracy that they represent even today a constant reference for the suicide studies. S. Freud, on his side, did never write any monograph on this matter, but fundamental observations on the self-suppression psychodynamic interpretation can be found in his works.

Attitude to Death↗
PubMed2004

The availability of body composition reference data for the elderly.

A significant public health issue is the nutritional, functional and health status of the elderly, many of whom live to very old ages, and three-quarters are living in developing countries. The assessment of health and nutritional status for the elderly needs improving in order to reduce health care costs. Health, function, disease and disability are associated with amounts of bone, fat and muscle in the body s composition. The ability to screen elderly persons for osteoporosis, obesity or sarcopenia requires normal distributions of measures of stature, weight and body composition in old age. Distribution statistics and selected percentiles for stature and weight are available from national health surveys in numerous countries. There are also numerous sets of body composition data collected from elderly persons around the world. These data sets provide important and valid descriptive information as a supplement to national reference data sets. The largest available data set for the elderly is the NHANES III, but in terms of numbers, the NHANES III sample of elderly is limited to availability of the 25th and 75th percentiles levels for stature, weight and BMI from 60 to 90 years of age for non-Hispanic Whites, and from 60 to 79 years of age for non-Hispanic Blacks and Mexican Americans.

Aged↗
PubMedDate not supplied

Reference data for evaluation of occupationally noise-induced hearing loss.

Relevant reference data are required in order to determine the effect from occupational noise exposure on hearing. Pure-tone averages (PTA) of hearing threshold levels simplify the evaluation for audiometric frequencies typically affected by noise. The present study provides reference data of high frequency (HF) PTA over 3, 4 and 6 kHz for a general adult population, aged from 20 to 79 years, not exposed to hazardous occupational noise. The results are presented as statistical distributions of HF PTA values as functions of age, and as prevalence of different degree of HF PTA in the age groups 20-29, 30-39, 40-49, 50-59, 60-69 and 70-79 years.

Adult↗
PubMed2004

Inferring dynamic properties of biochemical reaction networks from structural knowledge.

Functional properties of biochemical networks depend on both the network structure and the kinetic parameters. Extensive data on metabolic network topologies have been collected in databases, but much less information is available about the kinetic constants or metabolite concentrations. Depending on the values of these parameters, metabolic fluxes and control coefficients may vary within a wide range. Nevertheless, some of the parameters may have little influence on the observables of interest. We address the question whether, despite uncertainty about kinetic parameters, probabilistic statements can be made about dynamic network features. To this end, we perform a variability analysis of the parameters: assuming that the parameters follow statistical distributions, we compute the resulting distributions of the network properties like metabolic fluxes, concentrations, or control coefficients by Monte Carlo simulation. In this manner, we study systematically the possible distributions arising from typical topologies of biochemical networks such as linear chains, branched networks, and signaling and gene expression cascades. This analysis reveals how much information about dynamic behavior can be drawn from structural knowledge.

Biochemistry↗
PubMed2005

Severe thoracic kyphosis in the older patient in the absence of vertebral fracture: association of extreme curve with age.

BACKGROUND AND PURPOSE: Limited data exist on the natural history of thoracic kyphosis in elderly patients. The purpose of this study was to determine the statistical distribution of the thoracic kyphotic angle (TKA) measurement in older patients without vertebral body abnormalities when compared with a young population. METHODS: The TKA was measured by Cobb angle on digital lateral chest radiographs in 90 patients >65 years of age, 60 patients 51-65 years of age, 67 patients 36-50 years of age, and 63 patients 18-35 years of age. Patients with vertebral compression, vertebral body angulation, congenital anomaly, or significant scoliosis were excluded. RESULTS: In patients >65 years of age, average TKA was 41.9 degrees , but the distribution was unexpectedly bimodal, with a low mode at 28.3 degrees and an upper mode at 51.5 degrees (P < .001). Elderly women and men independently demonstrated a bimodal TKA distribution. Two-thirds of elderly women and half of elderly men had a TKA >40 degrees (upper mode). In young patients, average TKA was 26.8 degrees . In middle-aged patients, TKA was intermediate and nonbimodal. CONCLUSION: The TKA distribution in elderly patients (>65 years) without vertebral body abnormality is unexpectedly bimodal (non-normal distribution) with a subpopulation of patients significantly more affected by extreme kyphosis. Extreme thoracic kyphosis therefore occurs independently in a large subset of people, in the absence of vertebral wedge compression. The development of extreme thoracic kyphosis might contribute to excess biomechanical stress in the spine and may identify a population at risk for future vertebral compression fracture in particular at the thoracolumbar junction.

Adult↗
PubMed2005

u-Genome: a database on genome design in unicellular genomes.

Unicellular eukaryotes were among the first ones to be selected for complete genome sequencing because of the small size of their genomes and their interactions with humans and a broad range of animals and plants. Currently, ten completely sequenced unicellular genome sequences have been publicly released and as the number of available unicellular genomes increases, comparative genomics analysis within this group of organisms becomes more and more instructive. However, such an analysis is difficult to carry out without a suitable platform gathering not only the original annotations but also relevant information available in public databases or obtained by applying common bioinformatics methods. With the aim of solving these difficulties, we have developed a web-accessible database named u-Genome, the unicellular genome design database. The database is unique in featuring three datasets namely (1) orthologous proteins (2) paralogous proteins and (3) statistical distributions on exons, introns, intergenic DNA and correlations between them. A tool, Uniview, designed to visualize the gene structures for individual genes in the genome is also integrated. This database is of importance in understanding unicellular genome design and architecture and evolution related studies. The database is available through a web interface at http://sege.ntu.edu.sg/wester/ugenome.

Animals↗
PubMed1991

[The heart, the elderly, and diabetes mellitus. Epidemiologic study of 333 ambulatory clinical cases].

The paper proposes a new classification to describe the normal senile heart and its pathological forms: "small aortic heart" (nonhypertrophic-dilatative myocardiopathy and its ischemic form) and "large aortic heart" (hypertrophic-dilatative myocardiopathy and its ischemic form). The statistical distribution of 241 elderly patients with diabetes mellitus using this classification was compared to a control group of 92 elderly non-diabetic subjects. The results reveal the significant epidemiological incidence of ischemic cardiopathy with small aortic heart in diabetic patients compared to the control group in which more ischemic hypertrophic-dilatative cardiopathies were present. This observation supports the hypothesis that senile diabetic cardiopathy begins with a metabolic block with reduced contractile energy, and the overlying important ischemic component leads to the development of the small-size clinical phenotype.

Aged↗
PubMedDate not supplied

Anthropometry and body composition in the perspective of nutritional status in the elderly.

Understanding normal changes in the body's composition with old age and their health and nutritional implications is important in determining the nutritional status of the elderly. Suitable reference data for anthropometry and body composition obtained from large representative samples of black, white, Hispanic, and Asian elderly persons are needed to improve their nutritional health and care. Distribution statistics for body measurements of persons 65 to 80 years of age are available from national health and nutrition surveys, but for persons older than 80 years, there is little information. Recumbent anthropometric techniques have been developed that are applicable. Underwater weighing continues to be a gold standard for determining body composition in the elderly, but a four-compartment model would improve estimates of body composition in the elderly because of changes in the density of the fat-free mass with old age. Noninvasive methods such as anthropometry and bioelectric impedance could be used to predict body composition if they were validated against direct methods and if appropriate equations become available.

Aged↗
PubMed1991

[Results of laryngo-microscopic examinations over a 10-year period at the ORL Department of the Senta Hospital].

In the period from 1980-1989, 199 laryngomicroscopical examinations were conducted at our department. There were 20 cases of laryngeal carcinoma, 55 cases of keratosis with the presence of dysplasia in 21.8%, as well as 19 papillomas in adult individuals. In our material keratoses appear a few years before the onset of laryngeal carcinoma in an average statistical distribution. With one exception, the carcinomas were detected before the appearance of metastases. Our data indicate the exceptional benefit of laryngomicroscopy in the detection of precancerous lesions and carcinoma of the larynx.

Adolescent↗
PubMedDate not supplied

Platelet glycoprotein Ib polymorphism in the Italian population.

The glycoprotein Ib (GP Ib) is the major sialoglycoprotein on the platelet membrane and plays an important role in primary hemostasis. It was demonstrated that GP Ib is polymorphic: four different species of GP Ib (designated A, B, C and D) were observed, having molecular weights of 168, 162, 159 and 153 kiloDaltons, respectively. The polymorphism was first studied in the Japanese population and, subsequently, in Americans; a significant difference between the phenotype frequencies in the two populations was found. The authors report about GP Ib polymorphism patterns in the Italian population. GP Ib from normal subjects was analyzed by means of platelet protein SDS-PAGE followed by Western blotting; GP Ib species immobilized onto nitrocellulose filters were coupled with wheat germ agglutinin and stained using immunoperoxidase. Despite some differences in phenotype distribution, statistical analysis did not show differences between Italian and U.S. Caucasian phenotype frequencies: this is attributable to rather similar gene frequencies in the two populations. In our platelet samples we only observed three GP Ib types, precisely the B, C and D types; therefore we can confirm the rarity of the A type in Caucasians, while it was well represented in the Japanese population.

Alleles↗
PubMed1990

Incorporating dose-rate effects in Markov radiation cell survival models.

Markov models for the survival of cells subjected to ionizing radiation take stochastic fluctuations into account more systematically than do non-Markov counterparts. Albright's Markov RMR (repair-misrepair) model (Radiat. Res. 118, 1-20, 1989) and Curtis's Markov LPL (lethal-potentially lethal) model [in Quantitative Mathematical Models in Radiation Biology (J. Kiefer, Ed.), pp. 127-146. Springer, New York, 1989], which assume acute irradiation, are here generalized to finite dose rates. Instead of treating irradiation as an instantaneous event we introduce an irradiation period T and analyze processes during the interval T as well as afterward. Albright's RMR transition matrix is used throughout for computing the time development of repair and misrepair. During irradiation an additional matrix is added to describe the evolving radiation damage. Albright's and Curtis's Markov models are recovered as limiting cases by taking T----0 with total dose fixed; the opposite limit, of low dose rates, is also analyzed. Deviations from Poisson behavior in the statistical distributions of lesions are calculated. Other continuous-time Markov chain models ("compartmental models") are discussed briefly, for example, models which incorporate cell proliferation and saturable repair models. It is found that for low dose rates the Markov RMR and LPL models give lower survivals compared to the original non-Markov versions. For acute irradiation and high doses, the Markov models predict higher survivals. In general, theoretical extrapolations which neglect some random fluctuations have a systematic bias toward overoptimism when damage to irradiated tumors is compared with damage to surrounding tissues.

Cell Survival↗
PubMed1990

[Detection of self-administration of testosterone as an anabolic by determination of the ratio of urinary testosterone to urinary epitestosterone in adolescents].

Testing for illicit self-administration of testosterone by athletes requires quantitative analysis by gas chronomatography-mass spectrometry combined with stable isotope dilution. International Sports Authorities have adopted the ratio of urinary excretions of testosterone and epitestosterone for drug testing. This ratio is required to be under 6. The authors studied the statistical distribution of this ratio in teenage athletes and found that the likelihood of false-positive results is 15/10,000.

Adolescent↗
PubMed1990

Establishment of an external quality-assessment scheme for amino acid analyses: results from assays of samples distributed during two years.

Ten different samples of lyophilized plasma and two of liquid urine were distributed during two years to 26 laboratories performing quantitative amino acid analyses in a scheme designed to provide external quality assessment. After each distribution, statistical summaries and performance scores based on delta standard deviations and percentage biases from the all-laboratory trimmed means were returned to participants, who also received annual performance summaries based on their accumulated results. Coefficients of variation calculated from returns across all the samples ranged from 13% for glycine to 65% for methionine. Automated ion-exchange amino acid analyzers with ninhydrin detection appeared to perform better than other methods, although there was no clearly superior method and no model of analyzer clearly outperformed the others. These exercises demonstrate that there is room for improvement in the performance of quantitative amino acid analyses and that individual expertise may be more important in maintaining good performance than the choice of method or analyzer.

Amino Acids↗
PubMed1988

Biometry has to improve the quality of decision making both in biomedical research and in clinical practice.

The leading principles of biometrical design, evaluation and decision making in biomedicine can be summarized as follows: (1) formulation of the problem to be solved and of the specific question(s) to be answered; (2) definition of the population in study, ways of sampling and manoeuvres (treatments); (3) determining the kind and number of variables (time intervals of measurement, investigated biomedical parameters); (4) performing the pilot study if necessary (to arrange randomized blocks, to form hypotheses); (5) formulation of zero (alternative) hypothesis, setting the values of alpha(beta) risk; (6) ordering the sample sizes; (7) testing the type of statistical distribution and the homoscedasticity of the obtained data; (8) calculation of the point and interval (confidence, tolerance) estimates; (9) performing the chosen tests, e.g. on the significance of differences or correlations; and (10) the conclusions for science and practice, with eventual return to point (1) on a higher level of knowledge.

Biometry↗