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PubMed1985

Double-judgment psychophysics: problems and solutions.

Many paradigms for comparing identification thresholds with detection thresholds require the observer to make double judgments. We show that these paradigms can produce misleading results because of response biases and attentional shifts. For example, the subject's response bias plus correlated noise can mimic inhibition between channels. Some of these same problems can affect single-judgment paradigms. A detailed analysis of the double-judgment forced-choice paradigm reveals that there are a multiplicity of optimal strategies, some of which enhance identification over detection. Several improved analysis techniques for minimizing the effects of cognitive factors are proposed for both the double-judgment forced-choice paradigm and the double-judgment rating-scale paradigm. A classification scheme for distinguishing different types of interactions and correlations is developed. When the new rating-scale algorithm is applied to the detection of well-separated spatial frequencies, substantial masking but negligible inhibition is found. The rating-scale paradigm is shown to be useful in revealing not only the sensitivity and the interactions of the underlying mechanisms but also the observer's information-processing strategies.

Attention↗

PubMed1999

[Waldenström macroglobulinemia with diffuse large B-cell lymphoma that developed from a different B-cell clone].

A 62-year-old man was given a diagnosis of Waldenström macroglobulinemia (WM) in January 1995. He was treated with melphalan and corticosteroid until January 1996, when he experienced high fever and weight loss. The patient visited a nearby hospital, received a diagnosis of liver abscess, and was referred to our hospital on February 23, 1996. Computed axial tomographic scans demonstrated multiple isodensity masses in the liver, left adrenal region, and right kidney hilum. Needle biopsy specimens of a liver mass revealed infiltration of diffuse large B-cell lymphoma (REAL classification), suggesting that non-Hodgkin's lymphoma supervened WM. Despite multiple cycles of chemotherapy, the lymphoma responded poorly. The patient died of pneumonia and sepsis on May 10, 1996 and an autopsy disclosed broad involvement of liver and spleen with lymphoma. Southern blot analysis of DNA samples obtained from the patient's bone marrow at the time of the initial diagnosis of WM, and later from the needle biopsy specimen of liver mass, displayed different patterns of immunoglobulin heavy chain gene rearrangement. We therefore concluded that in this patient the lymphoma was not a progression of WM, but rather, an independent B-cell malignancy.

B-Lymphocytes↗

PubMed1989

[Social factors and arterial hypertension].

Hypertension in Hungary is classed as a potentially prevalent disease both because of its incidence and social consequences. Its origins can be traced back to environmental, economic and social changes. The aim of our analysis is: -to show the connections between hypertension development and the characteristics of social structure, life style and awareness. -to define social determination of hypertension and to evaluate it in view of applicability in prevention and treatment. Screening examination and sociological data collection was conducted in the 17th district of Budapest in 1982-83 in a random sample of patients between 20-64 years of age. While screening besides blood pressure measurement weight and height were measured, blood sugar content and serum lipid were determined and anamnestic particulars were recorded. Groups of topics of the sociological interview: -characteristics of social stratification and mobility -nutritional habits -smoking habits -leisure time physical activity -characteristics of work performed -social connections -critical personality traits -health care culture The 20-64 population of the 17th district is 39,456. Our analysis concerns 1,600 persons selected on a statistical basis. In the present lecture we analyse the connection between social stratification and life style and hypertension. Systolic and diastolic blood pressures are analysed separately as their biological characteristics are different. In our analysis blood pressure was treated as a continuous variable or was classified as normal marginal or high based on WHO criteria.2+ Systolic blood pressure of the surveyed population shown in Table I. Multiple regression or multivariable discriminant analyses were used to examine factors affecting classification into each group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1983

Quantitative criteria for prediction of the results after displaced fracture of the ankle.

In a series of 146 displaced ankle fractures, the effects of age, sex, side of injury, mechanism of injury, severity as determined by the Lauge-Hansen classification, type of injury (open or closed), open or closed treatment, and internal fixation of one or both malleoli were analyzed using subjective, objective, and radiographic parameters. Statistically significant prognostic features were identified and a prognostic scale was developed using multiple linear-regression analysis. The significant parameters were age, adequacy of the post-reduction positions of the medial and lateral malleoli, and completeness of the restoration of the deltoid ligament and distal tibiofibular syndesmosis. Open reduction proved superior to closed reduction, and in bimalleolar fractures open reduction of both malleoli was better than fixing only the medial side. Using the data on the first 109 fractures, a multiple linear-regression equation was formulated and used to predict the outcomes of the last thirty-seven fractures in the study. The accuracy of the predictions in them was 81 per cent.

Adolescent↗

PubMed1993

[Surgical wound infection: the risk factors and a predictive model].

BACKGROUND: The identification of the factors associated with infection of the surgical wound and the groups of patients with greatest risk of developing the same may aid in the elaboration of prevention strategies. METHODS: A prospective follow up study of a group of 1,143 patients admitted to general and digestive surgical departments in the Ramón y Cajal Hospital over a period of 7 months was carried out to determine the accumulated incidence of infection of the surgical wound and quantify the associated risk factors. A mathematical model was developed by logistic multiple regression analysis allowing the identification of groups of patients with high risk of infection which were internally evaluated posteriorly. RESULTS: Surgically intervened patients (70% of those admitted) developed a mean of 11 wound infections out of 100 patients. Five independent factors (age, surgical classification, length of intervention, presurgical stay, and presence of a central route) were associated to increased risk of infection. CONCLUSIONS: The factors associated with surgical wound infection identified in this study are related to the degree of wound contamination, the intrinsic risk of the patients and quality of health care. The model obtained is more efficient than the traditional surgical classification for the identification of groups of patients with high risk of infection.

Chi-Square Distribution↗

PubMed1994

Flow cytometric DNA analysis of submucosal carcinoma of the esophagus.

Carcinoma of the esophagus confined to the submucosa presents clinicopathologic features different from those of either carcinoma limited to the mucosa or more advanced lesions. The present study was designed to find out whether or not analysis of DNA content would yield prognostic information allowing the clinical outcome of carcinoma of the esophagus confined to the submucosa to be predicted. Cell nuclear DNA content was determined by flow cytometry in paraffin-embedded blocks from 55 patients with carcinoma of the esophagus confined to the submucosa. This allowed classification of DNA content into diploid and aneuploid patterns based on combined DNA histogram and cytogram data. The aneuploid pattern included typical, multiple clone and small clone aneuploid subtypes, as classified by our new criteria. A DNA aneuploid pattern was identified in 26 cases (47.3%) and found to correlate significantly with lymph node metastasis (P < 0.01). The incidence of distant metastasis was significantly higher in the aneuploid (4/26) than in the diploid (0/29) group (P < 0.05). The mortality from cancer within two years of surgery was significantly higher in the aneuploid (4/26) than in the diploid (0/29) group (P < 0.05). In conclusion, flow-cytometric DNA analysis is a valuable method for predicting malignant potential in carcinoma of the esophagus confined to the submucosa.

Adult↗

PubMedDate not supplied

Prognostic value of the modified TNM (Izumi) classification of hepatocellular carcinoma in 53 cirrhotic patients undergoing resection.

BACKGROUND/AIMS: Few studies have assessed the significance of prognostic factors in cirrhotic patients undergoing resection for hepatocellular carcinoma. METHODOLOGY: Overall survival and disease-free survival were evaluated in 53 cirrhotic patients undergoing hepatic resection for supervening hepatocellular carcinoma. The value of the UICC TNM classification, and the Izumi modified staging system on prognosis were analyzed. RESULTS: In multivariate analysis lack of micro/macrovascular invasion were predictive for long-term outcome. The difference between stages 1 and 2 or stage 3 and 4A using the UICC TNM classification was not significant with respect to survival or disease-free survival. UICC TNM classification was modified as follows; stage 1, solitary tumor without vascular invasion; stage 2, solitary or multiple tumor(s) involving adjacent vessel branch; stage 3, tumor(s) involving major vessel branch or with regional lymph node metastases; stage 4, tumor(s) with distant metastases. TNM (modified in accordance with Izumi) showed a significant difference between each stage with respect to survival and disease-free survival. CONCLUSIONS: A uniform tumor classification of hepatocellular carcinoma is advocated. Our results show that the UICC TNM classification for hepatocellular carcinoma is inadequate and may even on occasion lead to unnecessary resection. The modified staging system of Izumi is superior in determining outcome for cirrhotic patients with supervening hepatocellular carcinoma undergoing resection.

Adult↗

PubMedDate not supplied

Small subunit ribosomal DNA phylogeny of various microsporidia with emphasis on AIDS related forms.

Phylogenetic analysis of the small subunit ribosomal DNA of a broad range of representative microsporidia including five species from humans (Enterocytozoon bieneusi, Nosema corneum, Septata intestinalis, Encephalitozoon hellem and Encephalitozoon cuniculi), reveals that human microsporidia are polyphyletic in origin. Septata intestinalis and E. hellem are very similar to the mammalian parasite E. cuniculi. Based on the results of our phylogenetic analysis, we suggest that S. intestinalis be designated Encephalitozoon intestinalis. Furthermore, analysis of our data indicates that N. corneum is much more closely related to the insect parasite Endoreticulatus schubergi than it is to other Nosema species. This finding is supported by recent studies which have shown a similarity between E. schubergi and N. corneum based on the origin and development of the parasitophorous vacuole. Thus these opportunistic microsporidian parasites can originate from hosts closely or distantly related to humans. Finally, the phylogeny based on small subunit ribosomal DNA sequences is highly inconsistent with traditional classifications based on morphological characters. Many of the important morphological characters (diplokaryon, sporophorous vesicle, and meiosis) appear to have multiple-origins.

AIDS-Related Opportunistic Infections↗

PubMed2006

Classification of malignant gliomas by infrared spectroscopic imaging and linear discriminant analysis.

Infrared (IR) spectroscopy provides a sensitive molecular fingerprint for tissue without external markers. Supervised classification models can be trained to identify the tissue type based on the spectroscopic fingerprint. Infrared imaging spectrometers equipped with multi-channel detectors combine the spectral and spatial information. Tissue areas of 4 x 4 mm(2) can be analyzed within a few minutes in the macroscopic imaging mode. An approach is described to apply this methodology to human astrocytic gliomas, which are graded according to their malignancy from one to four. Multiple IR images of three tissue sections from one patient with a malignant glioma are acquired and assigned to the six classes normal brain tissue, astrocytoma grade II, astrocytoma grade III, glioblastoma multiforme grade IV, hemorrhage, and other tissue by a linear discriminant analysis model which was trained by data from a single-channel detector. Before the model is applied here, the spectra are shown to be virtually identical. The first specimen contained approximately 95% malignant glioma regions, that means astrocytoma grade III or glioblastoma. The smaller percentage of 12-34% malignant glioma in the second specimen is consistent with its location at the tumor periphery. The detection of less than 0.2% malignant glioma in the third specimen points to a location outside the tumor. The results were correlated with the cellularity of the tissue which was obtained from the histopathologic gold standard. Potential applications of IR spectroscopic imaging as a rapid tool to complement established diagnostic methods are discussed.

Artificial Intelligence↗

PubMedDate not supplied

Prenatal determination of demographic and attitudinal factors regarding feeding practice in an indigent population.

Demographic and attitudinal factors influencing the decision to breast- or bottle-feed were evaluated early in pregnancy by survey of 307 women in a low-risk prenatal obstetric clinic at a publicly funded hospital in Houston, Texas. Subjects responded to 17 demographic and 24 attitudinal questions. Racial classification revealed blacks 36.4%, whites 29.2%, and hispanics 30.8%. Twenty-five percent of the completed surveys were in Spanish. Of the total sample, 26.7% planned to breast-feed, 48.2% planned to bottle-feed, and 25.1% planned to do both. Multiple logistic regression analysis revealed six prominent independent risk factors for bottle-feeding. The most significant variable was lack of support for breast-feeding from a significant other (husband, mother, other relative, or friend), which had a odds ratio (OR) of 456.3. Other attitudinal variables achieving independent significance were disagreement with the statements "breastfeeding protects against disease" (OR = 4.0), "breasts were made for breastfeeding" (OR = 8.0), and "I want to know more about breastfeeding" (OR = 120.0). Significant demographic variables identified were completion of less than 12th grade (OR = 32.1), and age less than 35 years (OR = 43.3). These findings indicate the influence of significant others in the decision to breast-feed and suggest that future educational programs should require their inclusion if the prevalence of breast-feeding in this population is to be increased.

Adolescent↗

PubMed2003

MR imaging diagnosis of uterovaginal anomalies: current state of the art.

Uterovaginal anomalies are associated with a high incidence of decreased fertility and multiple obstetric problems. These anomalies are caused by alterations in development or fusion of the müllerian ducts. Uterovaginal anomalies are classified into three types: dysgenesis, vertical or lateral fusion defects, and unusual configurations. Systematic analysis of magnetic resonance (MR) images allows accurate morphologic demonstration and classification of uterovaginal anomalies, thereby indicating the appropriate treatment. The following parameters are recorded in MR images: uterine size, external fundal contour, intercornual distance, zonal anatomy, and presence of uterine or vaginal septa. Associated pelvic lesions or renal anomalies are to be reported. MR imaging allows diagnosis of obstructive uterovaginal anomalies; determining the site of obstruction is imperative for planning the proper surgical approach. MR imaging techniques, including planes, sequences, and the application of more recent advances, are discussed. Pelvic phase-array coils and endovaginal coils provide detailed images and can be problem-solving tools in complex anomalies. MR imaging findings associated with a variety of uterovaginal anomalies are shown. The author suggests a five-step approach for diagnosing uterovaginal anomalies with MR imaging.

Female↗

PubMed1995

First metatarsocuneiform motion: a radiographic and statistical analysis.

Fifty volunteers with 100 asymptomatic feet were evaluated by physical examination, radiographic analysis, and questionnaire. This investigation was used to evaluate first metatarsocuneiform motion and establish normal values at this joint. Normal first ray sagittal range of motion was 4.37 degrees (SD, +/- 3.4 degrees). The shape of the distal cuneiform was then categorized by three classification methods. Multiple independent variables were cross-referenced to determine their relationship with motion and shape at the distal cuneiform. Hyperflexibility of the thumb correlated with first ray hypermobility. No correlation was found between first ray motion and sex, age, intermetatarsal angle, side, skin stretch, hyperextension of the knee, hyperextension of the elbow, or shape of the distal cuneiform.

Adolescent↗

PubMed1985

Statistical prediction of cardiac risk in patients who undergo vascular surgery.

Since August 1982, an extensive computerized data base has been developed on all patients admitted to the Division of Vascular Surgery at the Ottawa Civic Hospital. For each patient, 180 variables are recorded, including information about preoperative risk factors and postoperative complications. Since cardiac complications are a major cause of mortality and morbidity, the data file has been used to study postoperative cardiac complications in patients who undergo arterial reconstructive operations. Between August 1982 and December 1983, 353 artery repairs were performed, excluding ruptured aneurysms. Cardiac complications developed following surgery in 56 patients. Risk factors were initially studied using contingency table analysis. Four of these factors were found to be significant: electrocardiographic evidence of previous myocardial infarction (p = 0.0003), nonspecific ST-segment changes (p = 0.0007), New York Heart Association classification of symptoms (p = 0.0003) and age (p = 0.01). A further statistical study was based upon multiple logistic regression. The authors believe that the identification of a high-risk group, using these criteria, is helpful in selecting patients for intensive preoperative investigation, including coronary arteriography.

Age Factors↗

PubMed2001

Outcome prediction in severe head injury: analyses of clinical prognostic factors.

Retrospective analysis of 272 patients with severe head injury was performed. Patient age, Glasgow Coma Scale (GCS) score, pupillary abnormalities, impaired oculocephalic response, presence of subarachnoid haemorrhage, and multiplicity of parenchymal lesions on computerised tomography (CT) were examined. The CT findings were divided into 2 groups, diffuse brain injury (DBI) and mass lesion, according to the classification of the Traumatic Coma Data Bank. The DBI, basically, has no high or mixed density lesion more than 25 ml on CT, and was classified into 4 subgroups: DBI I includes injuries where there is no visible pathology; DBI II includes all injuries in which the cisterns are present with a midline shift of less than 5 mm; DBI III includes injuries with swelling where the cisterns are compressed or absent and the midline shift is less than 5 mm; DBI IV includes injuries with a midline shift of more than 5 mm. The mass lesions were categorised into 3 subgroups: epidural haematoma; acute subdural haematoma; and intracerebral haematoma. Outcomes were determined at 6 months following trauma using the Glasgow Outcome Scale. All DBI I patients recovered well. In the DBI II group, age, GCS score and detection of multiple parenchymal lesions on CT were significantly correlated with outcome. For the DBI III and IV groups, the only significant prognostic factor was the GCS score. In patients with a mass lesion, the GCS score was the only significant prognostic factor in the epidural haematoma group, but the GCS score and the presence of subarachnoid haemorrhage were predictive factors in the acute subdural haematoma group. Outcomes were unfavourable in the majority of patients with intracerebral haematoma. GCS score could predict outcome in all groups. The confidence of the outcome prediction ranged from 75.8 to 92.1%, depending on logistic regression analysis.

Adolescent↗

PubMed1995

Prognostic factors in adenocarcinoma of the cardia.

BACKGROUND: The optimal extent of resection for adenocarcinomas of the gastroesophageal junction is controversial. This study was conducted to examine whether the extent of resection is an independent prognostic factor in cardia cancer. METHODS: The records and survival data of 125 patients who underwent resection for cancer of the cardia were retrospectively analyzed. Multiple regression was used to evaluate prognostic factors in patients who underwent proximal gastric resection (PR) or total gastrectomy (TG) for cancer of the cardia. RESULTS: Seventy-five patients underwent PR and 50 TG. The 5-year survival was 40% for tumors confined to the esophageal wall (T1, T2), and 13% in more advanced cases (T1, T2; P = 0.0001). Twenty-two percent of the patients with tumor-free margins, 10% of those with microscopic residual tumor, and none with macroscopic residual tumor survived longer than 5 years (P = 0.0001 for any residual tumor versus no residual tumor). Lymph node involvement (P = 0.002) and stage (P = 0.0001) were also significant in the univariate analysis. Five-year survival was 18% after TG, and 17% after PR (P = NS). CONCLUSION: Multiple regression identified residual tumor and penetration depth as independent predictors of survival (P = 0.0002, and P = 0.0001, respectively). After correction for these factors, none of the following variables were of additional significance: extent of resection (TG versus PR), lymph node involvement, age, or Lauren's classification. In 19 of 20 cases with microscopic incomplete resection, it was the oral margin that was positive. We conclude that the extent of resection (TG versus PR) does not influence survival in adenocarcinoma of the gastroesophageal junction.

Adenocarcinoma↗

PubMed2004

Multidimensional support vector machines for visualization of gene expression data.

MOTIVATION: Since DNA microarray experiments provide us with huge amount of gene expression data, they should be analyzed with statistical methods to extract the meanings of experimental results. Some dimensionality reduction methods such as Principal Component Analysis (PCA) are used to roughly visualize the distribution of high dimensional gene expression data. However, in the case of binary classification of gene expression data, PCA does not utilize class information when choosing axes. Thus clearly separable data in the original space may not be so in the reduced space used in PCA. RESULTS: For visualization and class prediction of gene expression data, we have developed a new SVM-based method called multidimensional SVMs, that generate multiple orthogonal axes. This method projects high dimensional data into lower dimensional space to exhibit properties of the data clearly and to visualize a distribution of the data roughly. Furthermore, the multiple axes can be used for class prediction. The basic properties of conventional SVMs are retained in our method: solutions of mathematical programming are sparse, and nonlinear classification is implemented implicitly through the use of kernel functions. The application of our method to the experimentally obtained gene expression datasets for patients' samples indicates that our algorithm is efficient and useful for visualization and class prediction. CONTACT: komura@hal.rcast.u-tokyo.ac.jp.

Algorithms↗

PubMed1992

Prediction of hormone responsiveness by mammographic parenchymal pattern in advanced primary breast cancer.

Ninety-two women with advanced, unilateral breast cancer were classified according to the Wolfe and Nottingham classifications of mammographic parenchymal pattern (MPP). Both classifications of MPP were significantly correlated to the estrogen receptor (ER) status of the breast carcinoma, but could not be used for prediction of response to hormonal therapy. Age distribution was significantly different among Wolfe types as well as between ER groups, but a multiple regression analysis showed that both age and Wolfe pattern were significant and independent predictors of the ER status.

Adult↗

PubMed2000

Reidentification of facultatively alkaliphilic Bacillus firmus OF4 as Bacillus pseudofirmus OF4.

With a view toward verifying the original classification of alkaliphilic Bacillus firmus OF4, physiological and biochemical characteristics were more extensively catalogued than in original studies, and this catalog was supplemented with 16S rDNA sequence homology and more extensive DNA-DNA hybridization analyses. Phylogenetic analysis of this alkaliphile based on the comparison of multiple 16S rDNA sequences from Bacillus species indicated that this strain is most closely related to Bacillus pseudofirmus. Consistently, in the DNA-DNA hybridization analysis of the alkaliphile and Bacillus reference strains, the highest level of DNA-DNA relatedness (96%) was found between the alkaliphile and the B. pseudofirmus type strain (DSM 8715(T)). The findings support the conclusion that this alkaliphile strain is more closely related to B. pseudofirmus than to B. firmus, and we propose the future use of the designation B. pseudofirmus OF4.

Bacillus↗