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PubMed2003

Graphic-based musculoskeletal model for biomechanical analyses and animation.

The ability to combine physiology and engineering analyses with computer sciences has opened the door to the possibility of creating the 'Virtual Human' reality. This paper presents a broad foundation for a full-featured biomechanical simulator for the human musculoskeletal system physiology. This simulation technology unites the expertise in biomechanical analysis and graphic modeling to investigate joint and connective tissue mechanics at the structural level and to visualize the results in both static and animated forms together with the model. Adaptable anatomical models including prosthetic implants and fracture fixation devices and a robust computational infrastructure for static, kinematic, kinetic, and stress analyses under varying boundary and loading conditions are incorporated on a common platform, the VIMS (Virtual Interactive Musculoskeletal System). Within this software system, a manageable database containing long bone dimensions, connective tissue material properties and a library of skeletal joint system functional activities and loading conditions are also available and they can easily be modified, updated and expanded. Application software is also available to allow end-users to perform biomechanical analyses interactively. This paper details the design, capabilities, and features of the VIMS development at Johns Hopkins University, an effort possible only through academic and commercial collaborations. Examples using these models and the computational algorithms in a virtual laboratory environment are used to demonstrate the utility of this unique database and simulation technology. This integrated system will impact on medical education, basic research, device development and application, and clinical patient care related to musculoskeletal diseases, trauma, and rehabilitation.

Algorithms↗
PubMed2001

Distance learning in academic health education.

Distance learning is an apparent alternative to traditional methods in education of health care professionals. Non-interactive distance learning, interactive courses and virtual learning environments exist as three different generations in distance learning, each with unique methodologies, strengths and potential. Different methodologies have been recommended for distance learning, varying from a didactic approach to a problem-based learning procedure. Accreditation, teamwork and personal contact between the tutors and the students during a course provided by distance learning are recommended as motivating factors in order to enhance the effectiveness of the learning. Numerous assessment methods for distance learning courses have been proposed. However, few studies report adequate tests for the effectiveness of the distance-learning environment. Available information indicates that distance learning may significantly decrease the cost of academic health education at all levels. Furthermore, such courses can provide education to students and professionals not accessible by traditional methods. Distance learning applications still lack the support of a solid theoretical framework and are only evaluated to a limited extent. Cases reported so far tend to present enthusiastic results, while more carefully-controlled studies suggest a cautious attitude towards distance learning. There is a vital need for research evidence to identify the factors of importance and variables involved in distance learning. The effectiveness of distance learning courses, especially in relation to traditional teaching methods, must therefore be further investigated.

Accreditation↗
PubMed2004

The hippocampal role in spatial memory and the familiarity--recollection distinction: a case study.

Memory for object locations and for events (comprising the receipt of an object) was tested in a case of developmental amnesia with focal hippocampal damage. Tests used virtual reality environments and forced-choice recognition with foils chosen to equalize the performance of control participants across conditions. Memory for the objects received was unimpaired, but the context of their receipt was forgotten. Memory for short lists of object locations was unimpaired when tested from the same viewpoint as presentation but impaired when tested from a shifted viewpoint. Same-view performance was disrupted by changing the background scene. These results are consistent with Jon having preserved matching to fixed sensory-bound representations but impaired reconstructed or manipulable representations underlying shifted-viewpoint recognition and episodic recollection.

Adult↗
PubMed2004

Quantitative trait loci affecting growth-related traits in wild barley (Hordeum spontaneum) grown under different levels of nutrient supply.

The genetic basis of phenotypic plasticity of relative growth rate (RGR), its components and associated morphological traits was studied in relation to nutrient limitation. In all, 140 F(3) lines from a cross, made between two Hordeum spontaneum (wild barley) accessions sampled in Israel, were subjected to growth analysis under two nutrient levels. Quantitative trait loci (QTLs) were detected for RGR and three of its components, leaf area ratio (LAR), specific leaf area and leaf mass fraction (LMF). Indications for close linkage (potential pleiotropy) were found, for example, for LAR and LMF. An interesting case is on chromosome 6, at which QTLs for RGR and seed mass were detected in the same region. These QTLs had opposite additive effects, supporting earlier results that plants growing from lighter seeds had a higher RGR. Only two QTLs were significant under both nutrient conditions, suggesting large QTL x environment interactions for most traits. For 21 out of 26 QTLs, however, the additive genetic effect was of identical sign in both nutrient environments, but reached the significance threshold in only one of them. Nevertheless, some QTLs detected in one of the two environments had virtually no effect in the other, and QTLs for plasticity were detected for RGR, LAR and LMF, as well as for some morphological traits. QTLs with opposite effects under high and low nutrients were not found. Thus, at the genetic level, there was no evidence for a trade-off between faster growth at high versus low nutrient levels.

Analysis of Variance↗
PubMed1997

The study of early human embryos using interactive 3-dimensional computer reconstructions.

Tracings of serial histological sections from 4 human embryos at different Carnegie stages were used to create 3-dimensional (3D) computer models of the developing heart. The models were constructed using commercially available software developed for graphic design and the production of computer generated virtual reality environments. They are available as interactive objects which can be downloaded via the World Wide Web. This simple method of 3D reconstruction offers significant advantages for understanding important events in morphological sciences.

Computer Communication Networks↗
PubMed1998

Computer-aided interactive three-dimensional reconstruction of the embryonic human heart.

Despite the fact that development of the human embryo heart is of considerable clinical importance, there is still disagreement over the process and the timing of events. It is likely that some of the conflicting accounts may have arisen from difficulties in describing and visualising 3-dimensional structures from 2-dimensional sections. To help overcome this problem and to improve our understanding of the development of the heart, we have devised techniques for the production of interactive 3D models reconstructed from serial histological sections of human embryos. Our method uses commercial software designed for the creation of 3D models and virtual reality environments. The ability to construct interactive visual images which both illustrate and communicate complex 3D information contributes to our understanding of the complex developmental changes occurring in embryogenesis.

Computer Graphics↗
PubMed2002

[Image processing in radiology].

Medical imaging processing and analysis methods have significantly improved during recent years and are now being increasingly used in clinical applications. Preprocessing algorithms are used to influence image contrast and noise. Three-dimensional visualization techniques including volume rendering and virtual endoscopy are increasingly available to evaluate sectional imaging data sets. Registration techniques have been developed to merge different examination modalities. Structures of interest can be extracted from the image data sets by various segmentation methods. Segmented structures are used for automated quantification analysis as well as for three-dimensional therapy planning, simulation and intervention guidance, including medical modelling, virtual reality environments, surgical robots and navigation systems. These newly developed methods require specialized skills for the production and postprocessing of radiological imaging data as well as new definitions of the roles of the traditional specialties. The aim of this article is to give an overview of the state-of-the-art of medical imaging processing methods, practical implications for the radiologist's daily work and future aspects.

Computer Simulation↗
PubMed2006

Playing the game on the World Wide Web.

ISSUE ADDRESSED: 'Celebrate - do it Safely' is a project aimed at reducing youth alcohol-related harm on the Central Coast, New South Wales (NSW). The primary focus for 2003 was to use the world wide web and the website www.celebratesafely.com.au to raise awareness and reinforce the message of how to party safely to young people. METHODS: A creative, interactive website was set up to be a local and reliable source of information regarding the risks associated with alcohol misuse. It was supported by a steering committee with diverse representation from key organisations. Content pages and links were developed to ensure access to information and contact details were simple and comprehensive. Topics such as a safe party checklist, safe driving, safe sex and protection from violence were included. Games and competitions emphasised the safe party message with clever actions and graphics created within a virtual party environment. The website was promoted by distribution of postcards throughout the school network. Radio campaigning, plus display of posters and banners throughout the area, raised the profile in the wider community. Key rings were given to young people along with free 'mocktails' to reinforce the message of safe partying. RESULTS: There has been an increase in website hits from 758 in 2002 to more than 65,000 in 2003. Written feedback from young people suggests the content and format is well designed for the target group. CONCLUSIONS: Promoting the message of safe celebration on the world wide web is an effective way of raising awareness in a local community about safe partying.

Adolescent↗
PubMed2004

Destabilization of the transmembrane domain induces misfolding in a phenotypic mutant of cystic fibrosis transmembrane conductance regulator.

Two phenotypic missense mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) channel pore (L346P and R347P in transmembrane (TM) segment 6) involve gain of a proline residue, but only L346P represents a significant loss of segment hydropathy. We show here that, for synthetic peptides corresponding to sequences of CFTR TM6 segments, circular dichroism spectra of wild type and R347P TM6 in membrane mimetic environments are virtually identical, but L346P loses approximately 50% helicity, implying a membrane insertion defect in the latter mutant. A similar defect was observed in the corresponding double-spanning ("hairpin") TM5/6-L346P synthetic peptide. Examination of the biogenesis of CFTR revealed that the full-length protein harboring the L346P mutation is rapidly degraded at the endoplasmic reticulum (ER), whereas the wild type and the R347P protein process normally. Furthermore, a second site mutation (R347I) that restores in vitro membrane insertion and folding of the TM5/6-L346P peptide also rescues the folding and cell surface chloride channel function of full-length L346P CFTR. The correlated in vitro/in vivo results demonstrate that destabilizing local hydrophobic character represents a sufficient signal for marking CFTR as a non-native protein by the ER quality control, with accompanying deleterious consequences to global protein folding events.

Amino Acid Sequence↗
PubMed2005

Influence of visually induced self-motion on postural stability.

CONCLUSION: Our results indicate that the illusion of self-motion is a significant factor leading to spatial disorientation. OBJECTIVE: Under normal circumstances, self-motion is perceived in response to motion of the head and body. However, under certain conditions, such as virtual reality environments, visually induced self-motion can be perceived even though the subject is not actually moving, a phenomenon known as "vection". The aim of this study was to examine the possible influence of illusory self-rotation (circular vection) on postural adjustments. MATERIAL AND METHODS: The subjects were 10 young females with no history of ocular or vestibular disease. Video-motion analysis was applied to measure postural movements during vertical optokinetic stimulation. RESULTS: For most subjects, movement of the visual surroundings induced head and body displacements in the same direction as that of the visual stimulus, regardless of the onset of self-motion perception. However, there was a significant increase in postural instability after the subjects began to perceive false self-motion in the opposite direction to that of the visual stimulus.

Adult↗
PubMed2006

Assessment of the quality of interaction in distance learning programmes utilizing the Internet or interactive television: perceptions of students and lecturers.

WebCT, a web-based virtual learning environment (VLE) and Interactive TV (ITV) are relatively new technologies that are used to deliver distance education at the Faculty of Health Sciences, Stellenbosch University. This study explores how effective current approaches to instructional design and interaction have been in utilizing these two technologies to support interaction and what lessons can be learnt. Five focus-group interviews were held with students and lecturers to assess the perceived quality of student-lecturer/student-student interactions. All students were invited to complete a questionnaire at the end of every module to assess their perceptions of interaction. Interaction was highly valued by students and lecturers participating in distance-learning programmes utilizing either VLE or ITV. Students rated courses using both technologies as moderately interactive. Significant differences between VLE and ITV were detected in student-lecturer and student-student interactions, use of additional modes of communication, instructional design, technological interactivity and social rapport activities. The groups did not differ across a number of likely barriers to interaction and both also reported the need for more flexible and better paced instructional designs.

Adult↗
PubMed2006

MolDIA: XML based system of molecular diversity analysis towards virtual screening and QSPR.

In this paper a new chemoinformatics tool for Molecular Diversity Analysis (MolDIA) is introduced. The objective of this system is the analysis of molecular similarity and diversity through the treatment of structural and physicochemical information. Current needs for chemical databases include the analysis, the management and the retrieval of chemical information. The implementation of eXtended Markup Languages (XML) is proposed as a basis for representing and structuring the chemical information contained in data structures and databases. The adequate descriptor vector and related physicochemical properties have been defined and constructed. The benefits of XML in chemoinformatics are discussed, as well as, the applications of this system in a virtual screening environment.

Computational Biology↗
PubMed2006

Rapid quantitative profiling of complex microbial populations.

Diverse and complex microbial ecosystems are found in virtually every environment on earth, yet we know very little about their composition and ecology. Comprehensive identification and quantification of the constituents of these microbial communities--a 'census'--is an essential foundation for understanding their biology. To address this problem, we developed, tested and optimized a DNA oligonucleotide microarray composed of 10,462 small subunit (SSU) ribosomal DNA (rDNA) probes (7167 unique sequences) selected to provide quantitative information on the taxonomic composition of diverse microbial populations. Using our optimized experimental approach, this microarray enabled detection and quantification of individual bacterial species present at fractional abundances of <0.1% in complex synthetic mixtures. The estimates of bacterial species abundance obtained using this microarray are similar to those obtained by phylogenetic analysis of SSU rDNA sequences from the same samples--the current 'gold standard' method for profiling microbial communities. Furthermore, probes designed to represent higher order taxonomic groups of bacterial species reliably detected microbes for which there were no species-specific probes. This simple, rapid microarray procedure can be used to explore and systematically characterize complex microbial communities, such as those found within the human body.

Adult↗
PubMed1998

Functional endoscopic sinus surgery training simulator.

OBJECTIVE/HYPOTHESIS: To determine the efficacy of a haptic (force feedback) device and to compare isosurface and volumetric models of a functional endoscopic sinus surgery (FESS) training simulator. STUDY DESIGN: A pilot study involving faculty and residents from the Department of Otolaryngology at The Ohio State University. METHODS: Objective trials evaluated the haptic device's ability to perceive three-dimensional shapes (stereognosis) without the aid of image visualization. Ethmoidectomy tasks were performed with both isosurface and volumetric FESS simulators, and surveys compared the two models. RESULTS: The haptic device was 77% effective for stereognosis tasks. There was a preference toward the isosurface model over the volumetric model in terms of visual representation, comfort, haptic-visual fidelity, and overall performance. CONCLUSIONS: The FESS simulator uses both visual and haptic feedback to create a virtual reality environment to teach paranasal sinus anatomy and basic endoscopic sinus surgery techniques to ear, nose, and throat residents. The results of the current study showed that the haptic device was accurate in and of itself, within its current physical limitations, and that the isosurface-based simulator was preferred.

Computer Simulation↗
PubMed2005

Mobile tele-echography: user interface design.

Ultrasound imaging allows the evaluation of the degree of emergency of a patient. However, in some instances, a well-trained sonographer is unavailable to perform such echography. To cope with this issue, the Mobile Tele-Echography Using an Ultralight Robot (OTELO) project aims to develop a fully integrated end-to-end mobile tele-echography system using an ultralight remote-controlled robot for population groups that are not served locally by medical experts. This paper focuses on the user interface of the OTELO system, consisting of the following parts: an ultrasound video transmission system providing real-time images of the scanned area, an audio/video conference to communicate with the paramedical assistant and with the patient, and a virtual-reality environment, providing visual and haptic feedback to the expert, while capturing the expert's hand movements. These movements are reproduced by the robot at the patient site while holding the ultrasound probe against the patient skin. In addition, the user interface includes an image processing facility for enhancing the received images and the possibility to include them into a database.

Algorithms↗
PubMed2005

Access to learning resources for students on placement in the UK: what are the issues and how can we resolve them?

AIM: To compile a list of the issues regarding access to learning resources which affect students on placement in the UK and suggest some ways in which these can be resolved. RESULTS: Issues relating to PC access, network access, software, firewalls, disciplinary procedures, electronic information resources, virtual learning environments, service level agreements, physical access to libraries, book loans, reading lists and course committees are identified and discussed in relation to NHS libraries. CONCLUSIONS: Successful resolution of the IT and library issues, which are increasingly inter-linked, can help to ensure that students have a positive placement experience. Resolution will depend on close, regular liaison and can be assisted by negotiation of a clear Service Level Agreement.

Access to Information↗
PubMed2000

Life at the oxic-anoxic interface: microbial activities and adaptations.

Molecular oxygen is one of the most important reactants in biogeochemical cycles. Due to its low solubility in water, the consumption of oxygen leads to the development of oxic-anoxic interfaces, which separate aerobic from anaerobic processes in virtually all environments, ranging in scale from oceanic sediments to the fecal pellets of a small soil invertebrate. Three case studies were selected to illustrate the basic situation and the specific characteristics of oxic-anoxic interfaces: sediments, the rhizosphere of aquatic plants, and the intestinal tract of insects. Each system is governed by the same general principles, but striking differences arise from, e.g., the nature of the major microbial activities and the mechanisms controlling metabolite fluxes. Also scale and dimensional differences as well as the consequences of temporal fluctuations are of fundamental importance. Recent developments in microbial ecology, which often combine traditional and modern approaches, have significantly furthered our understanding of the specific microniches and the metabolic and behavioral adaptations of microorganisms to life at the oxic-anoxic interface. New concepts help to define the targets of future studies: the spatial organization of microbial populations, their microenvironments and in situ activities, and the functional interactions within structured microbial communities.

Adaptation, Physiological↗