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PubMed1981

Leukemia revisited.

Selected features of the historical development of our knowledge of leukemia are discussed. The use of different methodologies for study of the nature of leukemic cell proliferation are analyzed. The differences between older cell kinetic data using tritiated thymidine and autoradiography and the newer cell culture methods are more apparent than real. It is suggested that tritiated thymidine and extracorporeal irradiation of the blood may be useful for therapeutic agents that have not been given an adequate trial. Radiation leukemogenesis presents an opportunity for study of the nature of leukemogenesis that has not been exploited adequately.

Animals↗
PubMed1981

[Metric examinations on the development of apical dendrites of cortical pyramidal cells during the postnatal time in the rat].

1. It is explained the postnatal evolution of some selected features of Golgi-impregnated layer V pyramidal neurons in the rat sensorimotor cortex from the 1st to the 90th day after birth (13 stages) quantitatively. Especially it is reported about the development of the length and the quantity of apical main dendrites and of the apical lateral branches from the 1st to the 3rd order as well as the branching behaviour of the dendrites (free ends of dendrites, branching points, ramification index). 2. The evolution of mean length of apical dendrites is represented by a sigmoidal polygon trace - like the classic growing curve. 3. During the 3rd month of the postnatal life the lateral branches of the apical dendrites show a distinct growing increase relating to the mean values of the total length of dendrites, their quantity and the branching behaviour. This intensification of growth is in contrast to the growing stagnation of the apical main dendrites in this time. 4. From this point of view it is deduced that relating to the maturation of pyramidal cells - contrary to the papers of other writers and contrary to a previous private conception - albino rats in the age of 3 months do not are differentiated cortical completely. 5. The several marks of pyramidal dendrites do not form themselves in the same time but successively. The maturing process of new dendrites or dendrite branches is the base of significant increase of the length. 6. It seems, that the formation of dendritic "tree" takes place in growing batches. In this context there are discussed the correlations between the morphometric conceivable changes in the cortical pyramids and the accession of functions in the animal.

Animals↗
PubMed1980

Aytpia status index of respiratory cells: a measurement for the detection and monitoring of neoplastic changes in squamous cell carcinogenesis.

A statistical procedure was developed for calculating an atypia status index (ASI) for cells from the bronchial mucosa. These indices represent the degree of abnormal changes in these cells and classify them as squamous metaplasia, mild atypia, moderate atypia, servere atypia or carcinoma. The classification accuracy of the procedure was more than 99% on trained data and was accomplished by minimizing the overlapping areas between the adjacent multivariate distributions of cell groups for selected features whose group means represent a monotonic function and for which the cell categories are distinguishable. The calculated ASI may reflect abnormal changes in the cell that may not be clearly evident visually. It appears that progression or reversal of bronchial epithelial atypia can be accurately monitored by studying the changes in the ASI, not only for preneoplasia but also for reactions to chemotherapy and various pulmonary infectious disease processes, such as influenza.

Adult↗
PubMed1995

Issues and challenges in the design of curriculum information systems.

Medical schools are increasingly using curriculum information systems to better manage their curricula, to incorporate alternative learning environments, to expand subject-specific instruction, or to adapt the curricula to the changing health care environment. A curriculum information system contains key features, selected by the system's designers, that describe the objectives, the specific content, and/or the educational activities that compose the curriculum. The underlying purpose of such a system is to document and describe the knowledge, behaviors, skills, attitudes, or activities students will be expected to develop or learn. While it might be ideal to have one system that would meet the needs of all possible users, the programming and maintenance requirements of such a single system would exceed most medical schools' resources. Thus, designers of curriculum information systems must first identify the primary intended-user group: students, faculty, or administrators. The system designed for one group will typically differ from the systems for other groups in the emphasis on and level of content detail and curriculum structure information. The general structure and purposes of curriculum information systems are expressed in three distinct system designs: a curriculum database (most helpful for administrators), a curriculum textbase (for faculty), and an electronic syllabus (for students). The authors describe these different designs, and they discuss challenges faced by system designers.

Curriculum↗
PubMed2026

Robust prioritization of genomic features with stability selection.

MOTIVATION: The heterogeneity of complex diseases including cancer leads to heavy-tailed distributions in the disease traits. In such settings, non-robust variable selection methods are inherently susceptible to data contamination and can yield unstable or misleading results. This vulnerability becomes more severe for recently proposed approaches that introduce pseudo-features as negative controls, as these methods further amplify the curse of dimensionality by expanding the genotype matrix in the presence of outliers and high-dimensional genomic features. RESULTS: We develop a robust variable selection framework with stability selection to prioritize genomic features in the presence of contamination. In contrast to existing approaches that rely on pseudo-features for error control, the proposed method achieves double robustness. First, it adopts least absolute deviation (LAD) LASSO to ensure robustness against outliers and heavy-tailed errors in disease traits. Second, it avoids augmenting the genotype matrix with pseudo-features, thereby mitigating the curse of dimensionality that is particularly problematic in high-dimensional genomic data. The proposed method has been extensively evaluated in simulation studies to demonstrate its effectiveness over multiple competing methods for variable selection. In addition, we have applied the proposed method and competing approaches to two real-data case studies: the The Cancer Genome Atlas (TCGA) Skin Cutaneous Melanoma (SKCM) dataset and an eQTL dataset. The results demonstrate that the proposed method achieves superior performance by identifying genomic features with higher reproducibility. AVAILABILITY AND IMPLEMENTATION: The source code for implementing the proposed methods is publicly available at https://github.com/cenwu/RSS with an archival DOI https://doi.org/10.6084/m9.figshare.32306883.

Genomics↗
PubMed1989

Aging, selective attention, and feature integration.

This study used feature-integration theory as a means of determining the point in processing at which selective attention deficits originate. The theory posits an initial stage of processing in which features are registered in parallel and then a serial process in which features are conjoined to form complex stimuli. Performance of young and older adults on feature versus conjunction search is compared. Analyses of reaction times and error rates suggest that elderly adults in addition to young adults, can capitalize on the early parallel processing stage of visual information processing, and that age decrements in visual search arise as a result of the later, serial stage of processing. Analyses of a third, unconfounded, conjunction search condition reveal qualitatively similar modes of conjunction search in young and older adults. The contribution of age-related data limitations is found to be secondary to the contribution of age decrements in selective attention.

Adult↗
PubMed1981

Caprine arthritis-encephalitis: clinical features and presence of antibody in selected goat populations.

Features of caprine arthritis-encephalitis, a retrovirus disease of domestic goats, were studied in 60 goats over a 10-year period. The rate of progression and the severity of the disease process were highly variable within and among animals, but the most salient features were chronically swollen joints and bursae, lameness, weight loss, poor coat, mineralization of soft tissue, and death. Of 1,160 goat serum samples from 24 states tested by the immunodiffusion technique, 81% were positive for antibody to caprine arthritis-encephalitis virus antigens.

Animals↗
PubMed1992

Interclinician agreement on the recognition of selected gross morphologic features of pigmented lesions. Studies of melanocytic nevi V.

BACKGROUND: Since the late 1970s clinical criteria for dysplastic melanocytic nevi (DMN) have been proposed and discussed. However, to our knowledge, no rigorous quantitative evaluation of the ability of examiners to agree on the gross morphologic features ascribed to DMN or atypical melanocytic lesions in general has been conducted. OBJECTIVE: The purpose of the study was to determine rates of interclinician agreement for recognizing seven clinical features associated with melanocytic lesions. METHODS: The gross morphologic features of 156 pigmented lesions, judged to be the clinically most atypical, from 156 consecutively examined patients with cutaneous melanoma were analyzed. Independent of the other clinicians' examinations, four physicians (two medical oncologists, one internist-epidemiologist, and one dermatologist-dermatopathologist) recorded seven gross morphologic features of the most atypical pigmented lesion on each patient. For up to 122 patients, the rates of interobserver agreement on recognizing these clinical features were measured by intraclass correlation. RESULTS: Among the clinical features assessed, the examiners noted macular components in 85.7% to 96.3% of lesions, asymmetry in 47.2% to 79.5%, irregular borders in 55.1% to 80.2%, ill-defined borders in 40.1% to 83.9%, and haphazard color in 40.8% to 73.9% of lesions. Despite this range of variance among examiners, there were statistically significant rates of interclinician agreement for the recognition of the latter features. There was less agreement in assessing individual colors within lesions. CONCLUSION: These findings substantiate that certain gross morphologic features routinely used in the clinical evaluation of melanocytic lesions can be recognized with a significant degree of reliability.

Adult↗
PubMed1995

Structural features mediating fibrin selectivity of vampire bat plasminogen activators.

The distinguishing characteristic of vampire bat (Desmodus rotundus) salivary plasminogen activators (DSPAs) is their strict requirement for fibrin as a cofactor. DSPAs consist of structural modules known from urokinase (u-PA) and tissue-type plasminogen activator (t-PA) such as finger (F), epidermal growth factor (E), kringle (K), and protease (P), combining to four genetically and biochemically distinct isoenzymes, exhibiting the formulas FEKP (DSPA alpha 1 and alpha 2) and EKP and KP (DSPA beta and DSPA gamma). Only DSPA alpha 1 and alpha 2 bind to fibrin. All DSPAs are single-chain molecules, displaying substantial amidolytic activity. In a plasminogen activation assay, all four DSPAs are almost inactive in the absence of fibrin but strongly stimulated by fibrin addition. The catalytic efficiency (kcat/Km) of DSPA alpha 1 increases 10(5)-fold, whereas the corresponding value of t-PA is only 550. The ratio of the bimolecular rate constants of plasminogen activation in the presence of fibrin versus fibrinogen (fibrin selectivity) of DSPA alpha 1, alpha 2, beta, gamma, and t-PA was found to be 13,000, 6500, 250, 90, and 72, respectively. Whereas all DSPAs are therefore more fibrin dependent and fibrin selective than t-PA, the extent depends on the respective presence of the various domains. The introduction of a plasmin-sensitive cleavage site in a position akin to the one in t-PA partially obliterates fibrin cofactor requirement. Fibrin dependence and fibrin selectivity of DSPAs are accordingly mediated by fibrin binding, which involves the F domain, as yet undefined determinants within the K and P domains, and by the absence of a plasmin-sensitive activation site. These findings transcend the current understanding of fibrin-mediated stimulation of plasminogen activation: in addition to fibrin binding, specific protein-protein interactions come into play, which stabilize the enzyme in its active conformation.

Aminocaproic Acid↗
PubMed1994

TBP-DNA interactions in the minor groove discriminate between A:T and T:A base pairs.

In this report, we test the hypothesis that TBP binds DNA promiscuously due to its manner of recognition of the DNA minor groove. The experiment performed was to select TBP-binding sequences from a pool of random double stranded oligonucleotides. Sixty two clones from this pool were sequenced. Surprisingly, the results show that TBP has a marked preference for stably binding one sequence (TATATAA) over all others, yet only four classes of TATA box were selected. The features of the selected sequences allow definition of a binding consensus for TBP. The DNA binding properties of TBP to the four TATA variants was examined, the results being in accord with the observed selection frequencies. However, the nature of TBP-DNA binding is strongly affected by ionic strength. We infer that recognition of DNA via the minor groove can be highly selective even where A:T and T:A discrimination is required. Models for how this might be accomplished are discussed.

Base Composition↗
PubMed1992

[Prognostic value of selected hemodynamic parameters featuring left ventricular systolic and diastolic function in patients with dilated cardiomyopathy].

UNLABELLED: The goal of the study was the choice of hemodynamic parameters most useful in prognosing the survival of the patients with dilated cardiomyopathy (DCM). The investigated group comprised 40 patients, who underwent left and right cardiac catheterization with left ventricular (LV) quantitative angiography. The day of catheterization was the starting point of the observation, which was performed by means of follow-up regular examinations and information from questionnaires sent to and returned by the patients or their families. The follow-up spanned from 1 to 120 months (means = 43). The hemodynamic parameters of LV systole, ejection, isovolumic relaxation and filling were assessed. The patients were divided into two subgroups featuring survival of less and more than 3 years, respectively. In these two subgroups the following parameters were compared: LVEADP, T constant of relaxation, LVEDP, LVEDVI,+dp/dt max, EF, LV mass/volume ratio, MCSD (midwall circumferential LV stress in early diastole), -dp/dt min. They were also correlated with survival and analyzed in Cutler-Ederer survival tables. CONCLUSIONS: 1. 32% of patients survived more than 5 years. 2. The prognostically most valuable parameters seem to be: -dp/dt min, LVEADP, LVEDVI, EF, LVEDP, MCSD, +dp/dt max. 3. The prognosing of survival in patients with DCM should be based on a multifactorial analysis because of lack of domination of any single factor.

Adolescent↗
PubMed1994

Selection of morphometric features that identify responders and nonresponders in stage IV Wilms' tumors.

Wilms' tumor is the most common renal malignancy of childhood. The use of histologic grade and stage has divided those patients into two main groups, responders and nonresponders, based on the absence or presence of extreme cytologic atypia (anaplasia). Patients with Wilms' tumor who have favorable histology experience excellent cure rates with relatively conservative treatment regimens. However, some patients with a favorable histologic diagnosis die of the disease. Destained hematoxylin and eosin-stained tissue sections were restained stoichiometrically with Feulgen stain, and 100 tumor cells per case were measured on a CAS 200 running CMP software. Using multivariant stepwise discriminant analysis on 13 cases of stage IV, favorable-histology Wilms' tumor, we successfully classified 92% of individuals into their correct prognostic groupings using 10 features of the quantitative morphology of tumor cells, including six Markovian textures. This morphometric technique may identify patients who can benefit from reduced therapy and those who must be treated with the more aggressive, classic therapy regimens.

Cell Nucleus↗
PubMed1993

Inattention and the perception of visual features.

Subjects selectively attended to one of two interleaved, novel figures while ignoring the other figure. In subsequent tests administered to determine the extent to which the ignored figure was perceived, recognition of shape and the location of contour gaps was at the chance level. Moreover, recognition of the presence of contour gaps was significantly below the chance level. These results indicate that preattentive visual processing of unattended objects is too crude to encode global shape and local features such as contour gaps. It is suggested that preattentive processing creates visual representations of unattended objects that contain very limited information about features.

Adult↗
PubMedDate not supplied

Segmental autotransplantation of the distal pancreas to the thigh: CT and ultrasound features.

In select patients with pancreatitis, pancreatectomy may be the only alternative for treatment of abdominal pain. Segmental autotransplantation of the distal pancreas to the thigh has been shown to be successful in preventing or reducing the severity of diabetes following pancreatectomy. We present the postoperative anatomy and potential complications identified on cross-sectional imaging.

Chronic Disease↗
PubMed1990

Selection criteria for surgery--clinical features and EEG including invasive techniques.

Preconditions, selection criteria for surgical treatment of epilepsy and some aspects of the presurgical evaluation are discussed. Identification of those patients who will profit from epilepsy surgery, exact localization of the seizure generating structures, and evaluation of the potential risks of the proposed operation are the main goals of the preoperative diagnostic procedures. The localizational value of certain seizure patterns and ictal clinical signs and symptoms is reviewed and illustrated with symptoms provoked by electrical stimulation of the brain.

Brain Mapping↗
PubMedDate not supplied

Responses of directionally selective neurons of the frog tectum mesencephali, their adaptation and extrapolation features.

Tectal directionally selective neurons were investigated in frogs. The highest measure of agreement in the character of response and dynamics of latent periods of neuron pairs was found with interelectrode distances of up to 300 mu, a fact which is evidently connected with the dimensions of the zones of ramification of the afferent fibers. Adaptation and extrapolation properties were discovered for most neurons and they were more marked in the nuclear layers of the tectum than in the fibrous layers. The more stable responses of neurons in the fibrous layers indicate the possible representation there of branches of fibers of the retinal ganglion cells, whereas neurons with high adaptivity (novelty neurons) are located in the nuclear layers.

Adaptation, Physiological↗