timrit Lengthens circadian period in a temperature-dependent manner through suppression of PERIOD protein cycling and nuclear localization.
A fundamental feature of circadian clocks is temperature compensation of period. The free-running period of ritsu (timrit) (a novel allele of timeless [tim]) mutants is drastically lengthened in a temperature-dependent manner. PER and TIM protein levels become lower in timrit mutants as temperature becomes higher. This mutation reduces per mRNA but not tim mRNA abundance. PER constitutively driven by the rhodopsin1 promoter is lowered in rit mutants, indicating that timrit mainly affects the per feedback loop at a posttranscriptional level. An excess of per+ gene dosage can ameliorate all rit phenotypes, including the weak nuclear localization of PER, suggesting that timrit affects circadian rhythms by reducing PER abundance and its subsequent transportation into nuclei as temperature increases. (+info)
A visual coding system in histopathology and its consensual acquisition.
Divergent descriptions of histopathologic images induce inter- and intra-observer variability in diagnosis. Even though a controlled terminology exists to describe medical imaging, pathologists do not always agree on the visual representation of the descriptive terms. The main purpose of our work is to define a methodology to build a standardized visual coding system unambiguously characterizing the terms of a microglossary. The methodology follows two steps: 1) the acquisition of experts' descriptions of images using the microglossary and 2) a consensus derivation. The procedure was applied on a set of 85 histopathological images of breast tumors described by two experts. Among the 339 objects selected in images, 176 were detected by both experts, 77% localized at the same place and 25% also identically labeled. The microglossary was enriched and illustrated via the resulting consensual descriptions. The contribution of this work supports relevant indexing of biomedical images and image-related information. (+info)
The clinical utility of the Revised European-American Lymphoma (R.E.A.L.) Classification: preliminary results of a prospective study in patients with non-Hodgkin's lymphoma from a single centre.
BACKGROUND: The clinical applicability of the Revised European-American Lymphoma (R.E.A.L.) Classification has been demonstrated in several retrospective studies. The present, ongoing study was initiated to evaluate the clinical and pathological utility of the R.E.A.L. Classification compared with the Working Formulation (WF) in a prospective fashion, in an unselected patient population treated at a single institution. PATIENTS AND METHODS: Prospective data were collected on 596 biopsies from 557 patients referred with an initial diagnosis of lymphoma. After initial histologic review, 465 biopsies from 441 patients were confirmed as non-Hodgkin's lyphoma (NHL), 412 of which could be classified in R.E.A.L. and WF. RESULTS: According to WF criteria, 25% were low grade, 58% intermediate grade and 2% high grade, 14% could not be allocated to a WF subtype. According to R.E.A.L., 46% were diffuse large B cell, 19% follicle centre lymphoma, 6% marginal zone, 6% small lymphocytic, 4% mantle cell, and 3% T-cell anaplastic large cell. For those with B-cell NHL, 7% were unclassifiable in WF compared with 1% in R.E.A.L. Corresponding figures for T-cell NHL were 68% and 3%, respectively. CONCLUSIONS: Preliminary results confirm the clinical utility of the R.E.A.L. Classification in a single institution setting, demonstrating that cases were more readily sub-typed in R.E.A.L. compared with WF. Frequencies are comparable with I.L.S.G. data. Further follow up with large patient numbers is on-going to analyse survival data with reference to clinical prognostic factors. (+info)
The interactive Web-based histology atlas system.
Molecular pathways and mechanisms underlying human cancer are frequently investigated in animal models. Studies to identify and dissect molecular pathways include the discovery of genes and their subsequent analysis in transgenic and 'knock-out' mice. A critical aspect in such investigations is the evaluation of organ integrity and histology upon the alteration or inactivation of specific genes. Results from such studies are usually published in scientific journals. However, due to print space and costs the display of large high quality images is limited. Furthermore, the printed media does not permit an easy comparison of histological images published in different journals and different years. The Internet provides a tool for the timely and inexpensive dissemination of scientific data to the research community. However, its potential for the analysis of histological images has not been explored. Here we present a web-based interactive histology atlas (http://histology.nih.gov) that permits the retrieval of annotated, high-resolution histology images via the Internet. This histology atlas also takes advantage of the interactive nature of the Internet to support the communication between different research groups. As an outline forum this atlas provides the framework to evaluate and understand cancer pathology, and to develop a consensus between veterinary and human pathologists. (+info)
A property concept frame representation for flexible image-content retrieval in histopathology databases.
In histopathology databases, images descriptions are collections of properties provided by experts. Image content retrieval implies comparison of such properties. The objective of this work is to enrich the traditional attribute-value representation of properties in order to take into account the polymorphism and subjectivity of properties and to manage the comparison process. In this paper we define a property concept frame (PCF) representation based on fuzzy logic to handle both representation and comparison. Seven quantifiable morphological characteristics were selected from histopathological reports to illustrate the variety of fuzzy predicates and linguistic terms in properties. The PCF representation has been tested in the context of breast pathology. It is concluded that the PCF representation provides a unification scheme to retrieve in images morphological characteristics that are described in different ways. It may enhance the relevancy of applications in various contexts such as image content-based retrieval or case-based reasoning from images. (+info)
Comparison of a virtual microscope laboratory to a regular microscope laboratory for teaching histology.
Emerging technology now exists to digitize a gigabyte of information from a glass slide, save it in a highly compressed file format, and deliver it over the web. By accessing these images with a standard web browser and viewer plug-in, a computer can emulate a real microscope and glass slide. Using this new technology, the immediate aims of our project were to digitize the glass slides from urinary tract, male genital, and endocrine units and implement them in the Spring 2000 Histology course at the University of Iowa, and to carry out a formative evaluation of the virtual slides of these three units in a side-by-side comparison with the regular microscope laboratory. The methods and results of this paper will describe the technology employed to create the virtual slides, and the formative evaluation carried out in the course. Anat Rec (New Anat) 265:10-14, 2001. (+info)
Introducing a reward system in assessment in histology: a comment on the learning strategies it might engender.
BACKGROUND: Assessment, as an inextricable component of the curriculum, is an important factor influencing student approaches to learning. If assessment is to drive learning, then it must assess the desired outcomes. In an effort to alleviate some of the anxiety associated with a traditional discipline-based second year of medical studies, a bonus system was introduced into the Histology assessment. Students obtaining a year mark of 70% were rewarded with full marks for some tests, resulting in many requiring only a few percentage points in the final examination to pass Histology. METHODS: In order to ascertain whether this bonus system might be impacting positively on student learning, thirty-two second year medical students (non-randomly selected, representing four academic groups based on their mid-year results) were interviewed in 1997 and, in 1999, the entire second year class completed a questionnaire (n = 189). Both groups were asked their opinions of the bonus system. RESULTS: Both groups overwhelming voted in favour of the bonus system, despite less than 45% of students failing to achieve it. Students commented that it relieved some of the stress of the year-end examinations, and was generally motivating with regard to their work commitment. CONCLUSIONS: Being satisfied with how and what we assess in Histology, we are of the opinion that this reward system may contribute to engendering appropriate learning approaches (i.e. for understanding) in students. As a result of its apparent positive influence on learning and attitudes towards learning, this bonus system will continue to operate until the traditional programme is phased out. It is hoped that other educators, believing that their assessment is a reflection of the intended outcomes, might recognise merit in rewarding students for consistent achievement. (+info)
Laboratory instruction in histology at the University at Buffalo: recent replacement of microscope exercises with computer applications.
Histology is a morphologic science in which the structure of the cells, tissues, and organs of the body are examined with a microscope. In the laboratory courses in histology at the School of Medicine of the University at Buffalo, histologic specimens had been used since the late 19th century to teach the principles of cell, tissue, and organ structure. Students also had to learn how to analyze or "read" slides with a microscope. Learning histology in this way, i.e., by direct examination of actual specimens, is time consuming and viewed by some as unnecessary. As a result of recent curricular reform at the School of Medicine that reduced contact time in histology, half of all laboratory exercises that would have been performed with a microscope were performed instead with interactive computer applications. By replacing some microscope exercises with more efficient computer applications, the histology course accommodated curricular change by both reducing contact time and continuing to offer valuable microscope laboratories for most of the organ systems of the body. To provide a basis for comparing traditional microscope exercises with computer-assisted instruction in histology, the nature of the laboratory experience between 1846 and 1998 is briefly reviewed. The instructional strategy behind the use of computers is presented, along with the nature of the computer applications and the means by which the computer applications were incorporated into the school's laboratory course in histology. (+info)