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PubMed1999

A search engine for virtual patient records.

Virtual patient records provide a means for integrated access to patient information that may be scattered around different healthcare settings. Within the boundaries of a health district providing all levels of care, this concept can be implemented in an Intranet environment to support longitudinal patient care activities across the participating healthcare providers. Since medical information is stored on multiple Intranet sites in various forms (e.g. codified data, transcribed documents, and images), a suite of appropriate tools is needed to enable access to such information in combined form. In most cases, however, access to medical information should be restricted to authorized users. To serve this purpose, a prototype search engine incorporating an authorization and access control functionality has been developed and presented in this paper. The system is based on the signature file access method and an experimental implementation written in JAVA is also described.

Database Management Systems↗
PubMed2005

Coloscopy simulation: towards endoscopes improvement.

Minimally invasive surgery progresses have allowed to greatly decrease patient suffering. A way to improve these techniques is to use active tools, which could adapt to the inspected environment. The development of these tools is very complex. So simulation methods can be significantly helpful in order to produce the most suitable tools while limiting the quantity of physical prototypes. We work on the design of a simulator for virtual coloscopy. Besides the virtual prototyping aspect for new active endoscopic devices, we can also use it as a training simulator once the device is designed. To do so, we have to address the simulation process of the colon. This article is mainly devoted to the description of the chosen models for the colon behaviour, which are used for the simulator. Some experimental results are presented which confirm the validity of the different choices. To finish, sigmoid untwisting operation is presented as a benchmark test to prove the efficiency of the simulator.

Animals↗
PubMed2005

Function of a fly motion-sensitive neuron matches eye movements during free flight.

Sensing is often implicitly assumed to be the passive acquisition of information. However, part of the sensory information is generated actively when animals move. For instance, humans shift their gaze actively in a sequence of saccades towards interesting locations in a scene. Likewise, many insects shift their gaze by saccadic turns of body and head, keeping their gaze fixed between saccades. Here we employ a novel panoramic virtual reality stimulator and show that motion computation in a blowfly visual interneuron is tuned to make efficient use of the characteristic dynamics of retinal image flow. The neuron is able to extract information about the spatial layout of the environment by utilizing intervals of stable vision resulting from the saccadic viewing strategy. The extraction is possible because the retinal image flow evoked by translation, containing information about object distances, is confined to low frequencies. This flow component can be derived from the total optic flow between saccades because the residual intersaccadic head rotations are small and encoded at higher frequencies. Information about the spatial layout of the environment can thus be extracted by the neuron in a computationally parsimonious way. These results on neuronal function based on naturalistic, behaviourally generated optic flow are in stark contrast to conclusions based on conventional visual stimuli that the neuron primarily represents a detector for yaw rotations of the animal.

Animals↗
PubMed1997

Computer assisted therapy for multiple sclerosis and spinal cord injury patients application of virtual reality.

For patients with multiple sclerosis and spinal cord injury, virtual reality systems provide new methods of assistance with dysmetria, tremor, spasticity, and weakness. Robust mechanisms exist within the central nervous system to produce neuroplastic adaptive responses operative in retraining motor activities. Haptic systems cued by the patient's visual environment can produce force corridors to guide a patient's wrist and hand in the performance of specific tasks. Such haptic application can substantially reduce motor instability and improve performance. Preliminary clinical approaches, using video tremor tracking and manual force application, indicate the extent of the expected improvements attainable with this approach. Refinement of these techniques is proceeding to development of VR systems that will allow more extensive application to the problems of dysmetria, more general instances of tremor, spasticity, and weakness.

Humans↗
PubMed1989

Toward the necessary universalizing of a disability policy.

Issues confronting people with disabilities do not result solely from physical or mental impairment, but from the fit between impairments and practically every feature of the social, economic, physical, and political environment. Changes in housing, transportation, and employment policies would augment the quality of daily living for those with disabilities today and in the future. With the entire population facing chronic illness and activity limitations, a universal approach to disability is virtually required, rather than policies focusing exclusively on a person's special needs. The absence of such a universal perspective will lead to the expansion and perpetuation of the segregated and unequal society visible at present.

Aged↗
PubMed1994

Long-term delayed vascularization of human neural transplants to the rat brain.

Human neural transplants are being developed to treat Parkinson's disease. Previous characterization of human transplants focused on neuronal development, while little is known of the interaction between the transplant and its environment, among which blood is of prime importance. We evaluated here the formation of blood vessels in human neural xenografts placed into the brain of rats immunosuppressed with cyclosporin A. Using capillary wall markers, we found that human transplants remain virtually nonvascularized for more than 1 month. Angiogenesis takes place very slowly and the density of blood vessels is still quite poor after 3 months, the fine structure of these capillaries, when they form, is apparently normal. Functional studies indicate that the vascular network formed in the transplant allows blood circulation and exhibits a working barrier to macromolecules. Glucose uptake and consumption and cytochrome oxidase activity are almost undetectable up to 3 months after grafting. These results demonstrate that vascularization is much delayed in human xenografts into the rat brain. This delay is likely to be dependent on the maturation of the transplanted tissue. A dedifferentiation of human endothelial cells cotransplanted with neural cells occurs since histochemical and immunocytochemical markers revealing endothelial cells in the human fetus are not present up to 1 month in the transplant. The origin of this phenomenon is a matter of speculation. How neural cells survive and mature in such conditions are issues of prime interest for the future of human neural grafting.

Animals↗
PubMedDate not supplied

[Acute renal insufficiency in rats in compensatory renal hypertrophy].

Sodium bichromate and glycerol were administered to compare the course of acute renal failure in uninephrectomized rats and rats with two kidneys. The blood serum levels of creatinine, urea, sodium, potassium and osmotically active agents were found to be rather similar in the rats with one and two rats two days after the administration of nephrotic compounds. The concentration of electrolytes in the renal cortex and papilla of these animal groups. It is concluded that acute renal failure caused by glycerol and bichromate runs virtually similarly both in animals with one and two kidneys. Thus, in emergency, such as acute renal failure, the compensatorily hypertrophied kidney ensures the same elimination of nitrogen metabolic-waste products and maintains the electrolytic composition of the internal environment as in the animals with two working kidneys.

Acute Kidney Injury↗
PubMed2001

Beyond the electronic textbook model: software techniques to make on-line educational content dynamic.

OBJECTIVE: We describe a working software technology that enables educators to incorporate their expertise and teaching style into highly interactive and Socratic educational material for distribution on the world wide web. MATERIALS/METHODS: A graphically oriented interactive authoring system was developed to enable the computer novice to create and store within a database his or her domain expertise in the form of electronic knowledge. The authoring system supports and facilitates the input and integration of several types of content, including free-form, stylized text, miniature and full-sized images, audio, and interactive questions with immediate feedback. The system enables the choreography and sequencing of these entities for display within a web page as well as the sequencing of entire web pages within a case-based or thematic presentation. Images or segments of text can be hyperlinked with point-and-click to other entities such as adjunctive web pages, audio, or other images, cases, or electronic chapters. Miniature (thumbnail) images are automatically linked to their full-sized counterparts. The authoring system contains a graphically oriented word processor, an image editor, and capabilities to automatically invoke and use external image-editing software such as Photoshop. The system works in both local area network (LAN) and internet-centric environments. An internal metalanguage (invisible to the author but stored with the content) was invented to represent the choreographic directives that specify the interactive delivery of the content on the world wide web. A database schema was developed to objectify and store both this electronic knowledge and its associated choreographic metalanguage. A database engine was combined with page-rendering algorithms in order to retrieve content from the database and deliver it on the web in a Socratic style, assess the recipient's current fund of knowledge, and provide immediate feedback, thus stimulating in-person interaction with a human expert. RESULTS: This technology enables the educator to choreograph a stylized, interactive delivery of his or her message using multimedia components assembled in virtually any order, spanning any number of web pages for a given case or theme. An educator can thus exercise precise influence on specific learning objectives, embody his or her personal teaching style within the content, and ultimately enhance its educational impact. CONCLUSION: The described technology amplifies the efforts of the educator and provides a more dynamic and enriching learning environment for web-based education.

Computer-Assisted Instruction↗
PubMed2005

A mechanical contact model for the simulation of obstetric forceps delivery in a virtual/augmented environment.

During the process of human childbirth, obstetric forceps delivery can be a justified alternative to emergency Caesarean section when normal vaginal delivery proves difficult or impossible. Currently, training of forceps interventions is mainly done on real patients which poses a risk. This paper describes a pilot project on the simulation of training of obstetric forceps delivery, using Virtual Reality technology. We first give a brief historical review of the concept of 'birth simulation' and describe the current implementation of the interface. Then we report a number of experiments, conducted to test the feasibility of a real-time mechanical contact model to describe the interaction between the forceps and fetal head, eventually to be interfaced with a multi-purpose haptic feedback device. It is concluded that an explicit dynamic model to calculate the deformation of the main fetal skull bones only, or a quasi-static model to calculate the deformation of the fetal head in its entirety, can reach real-time performance.

Computer Simulation↗
PubMed1994

A computer-controlled system for post-stimulus time histogram and wind-up studies.

A LabVIEW 2 virtual instrument (VI)-based system is described for stimulation of sensory fibers in peripheral nerves and analysis and storage of electrophysiological data recorded from the spinal cord. The system utilizes a commercially available multifunction data acquisition (input/output; I/O) board, graphical programming environment and custom built VIs. Electrical stimuli are triggered by the I/O board and delivered at C-fiber strength to the receptive field of a multireceptive dorsal horn neuron. The stimulus frequency can be chosen between 0.1 and 1 Hz. Extracellular action potentials are recorded with a compound recording/iontophoresis carbon-fiber microelectrode and sampled by the I/O board. Post-stimulus time histograms (PSTH) are computed to visualize the preferred times of neuronal firing evoked by A- and C-fiber inputs. Responses of the neuron to repetitive stimulation are analyzed by their latency relative to the stimulus and plotted against the stimulus number. Wind-up, the progressive potentiation of C fiber-evoked response per stimulus, is increased by NMDA and decreased by MK-801 when each is applied by microiontophoresis. The system is well suited to perform combined PSTH and wind-up analysis on-line as well as to examine previously recorded data off-line. Principles of operation and diagrams of greater importance are explained in detail. To illustrate system operation, sample recordings, PSTH and wind-up analyses from a dorsal horn neuron are presented. The software is available from the author.

Action Potentials↗
PubMed2001

Two-phase partitioning bioreactors: a new technology platform for destroying xenobiotics.

Toxic organic compounds (xenobiotics) pose serious environmental and health risks worldwide. Biological treatment of these materials is severely constrained by their toxic and inhibitory nature and great care is required with respect to the rate at which they are provided to cells. The use of a second, distinct, organic phase in a bioreactor has been shown to provide a virtually foolproof means of feeding substrate to cells because this process concept relies only on thermodynamic equilibrium and the cells' own rate of metabolism. This technology can be applied to stockpiled xenobiotics as well as contamination of air, water and soil environments.

Biodegradation, Environmental↗
PubMed1994

Active site coordination chemistry of the cytochrome c peroxidase Asp235Ala variant: spectroscopic and functional characterization.

Asp235 in yeast cytochrome c peroxidase forms a hydrogen bond with His175, the proximal histidyl residue, that has been suggested to be important in determining the electronic properties of the heme iron and that may be involved in stabilizing the higher oxidation states of the peroxidase that form transiently during catalysis. The current study employs 1H and 15N-NMR spectroscopy to study the electronic properties of and the effects of pH on the active site of the Asp235Ala variant. This variant exhibits three spectroscopic species between pH 5 and 9: a high-spin species that forms at low pH and two low-spin species that form successively at higher pH. Nevertheless, the activity of the variant exhibits a pH dependence virtually identical to that of the wild-type protein, though the activity of the variant is 3 orders of magnitude lower at all values of pH between pH 5 and 8.5. These findings suggest that the spin state and coordination environment of the heme iron in cytochrome c peroxidase do not dictate the rate of substrate (cytochrome c) oxidation. Binding of cyanide to the variant enzyme results in formation of a single species as detected by NMR spectroscopy. Analysis of high-resolution 1D and 2D 1H-NMR and 15N-NMR spectra of the cyanide adduct has permitted characterization of the properties of this derivative and the strength of the proximal ligand bond to the heme iron. Disruption of the hydrogen bond between the proximal histidine and Asp235 that exists in the wild-type enzyme dramatically reduces the strength of the interaction between the proximal ligand and the iron; this effect combined with concurrent changes in the distal heme-binding pocket accounts for the increase in reduction potential reported for the Fe3+/Fe2+ couple. The catalytic consequences of the structural and electronic properties of the variant elucidated in this study are discussed.

Alanine↗
PubMed1996

Saturation diving as a submarine rescue tool.

The U.S. Navy Submarine Rescue Diving and Recompression System (SRDRS) uses saturation diving to provide human intervention at the hatch of a disabled submarine. The system incorporates the basic elements of traditional saturation diving platforms to provide life support to divers at the worksite as well as in a decompression chamber in between work assignments. The demands of the submarine rescue mission require that the system provide quick response to an emergency virtually anywhere in the world. To answer these demands, SRDRS uses a mixture of state-of-the-art diving technologies and traditional approaches to life support in a quickly mobilized, easily transportable diving system capable of operating in extremely harsh environments.

Air Conditioning↗
PubMed2004

U.S. Department of Veterans Affairs Enterprise Reference Terminology strategic overview.

The Veterans Health Affairs (VHA) branch of the Department of Veterans Affairs has undertaken an Enterprise Reference Terminology (ERT). VHA, arguably the largest integrated healthcare provider in the United States, has completely computerized virtually all clinical transactions, including physician orders and documentation. The VA is now integrating its clinical records across hundreds of sites of care by means of a Health Data Repository (HDR) project. ERT has been designed to provide a terminology development environment, terminology services, and maintenance services for the clinical and business content in HDR and other VHA applications. Drug, laboratory observations, and clinical document title files have been developed, and the ERT will encompass all HDR domains by 2008. Commercial tools are used to host the VHA's ERT terminology development and server environments. We will select and adopt both open-source and licensable terminology systems to provide ERT content, as well as reuse existing VA-specific terminology content.

Hospital Information Systems↗
PubMed1989

The human skin mast cell.

The abundance of mast cells in human dermis, together with their ability to release a variety of vasoactive and pro-inflammatory mediators following cross-linkage of their cell-surface receptors for IgE, enables these cells to provide an effective defence mechanism within this organ. A similar defensive function is attributed to mast cells of other human organs such as intestine and lung which are in contact with the external environment and therefore susceptible to infiltration by foreign allergens and micro-organisms. However, mast cells of the skin apparently differ from those present in lung and intestine in being activated for histamine release by a variety of endogenous neuropeptides which stimulate the rapid release of histamine in the virtual absence of eicosanoids. This would provide a mechanism of neurogenic control of a variety of homeostatic functions such as blood flow, angiogenesis and fibroblast proliferation. Such processes would aid in the remodelling of tissue during wound healing, and increased numbers of mast cells have been noted around healing wounds of rat skin and areas of developing fibrosis. Neuropeptides modulate the activity of a variety of immuno-competent leucocytes including macrophages, monocytes and lymphocytes. The findings that skin mast cells are activated by neuropeptides suggest that these cells may also be included amongst those involved in neuro-immune interactions. Activation of skin mast cells by non-immunological stimuli may contribute to the aetiology of some forms of skin disease. Patients with chronic idiopathic urticaria appear to have enhanced vascular responsiveness to intradermal injections of the histamine liberator codeine suggesting that this disease may involve hyper-responsiveness of their mast cells to endogenous non-immunological stimuli. The findings of large increases in histamine accompanied by small increases in PGD2 in venous effluent of thermally challenged limbs of patients with cold- or heat-induced urticaria may suggest that their mast cells had been activated by a non-immunological stimulus. However, the interpretation of results gained using such relatively complex in-vivo systems are difficult, as the cellular origin of the detected mediators is by no means clear. However, it is hoped that in the future the alliance of newly developed in-vitro techniques to investigate mast cell function together with in-vivo methods to investigate their interaction with elements in their tissue environment will greatly increase our understanding of the role of the human skin mast cell in health and disease.

Histamine↗
PubMedDate not supplied

Nontraditional work factors in farmworker adolescent populations: implications for health research and interventions.

Agriculture has been documented to be one of the most hazardous work environments for both adults and children. Adolescents may be especially vulnerable to adverse health effects from agricultural exposures due to the rapid growth and development experienced during those years. Separating the occupational, economic, and social issues in this population is difficult. Weak regulatory protection, lack of compliance with existing regulations, and gaps in service provision characterize the working conditions of adolescent farmworkers. Although there is increasing research on the impact of work organization on mental and physical health in adult working populations, there is a scarcity of research focused on this concept in young workers--and it remains virtually unaddressed in young farmworkers. Work characteristics of the informal work sector, better delineated in international literature, should be considered when planning research or interventions in this at-risk population. Further, the population of adolescent farmworkers is diverse, and research strategies and interventions need to be targeted and tailored to the heterogeneous groups. This article addresses some of the nontraditional work factors associated with the less-than-formal work organization and environments in the farmworker adolescent population and how these factors may inform the planning of research and interventions. Specifically, mobility, cultural patterns and social networks, alternative sampling strategies, alternative delivery of health care and education, and involvement of a wide range of players in the work environment of adolescent farmworkers should all be considered when conducting research or planning programs for this population.

Adolescent↗
PubMed2001

A full 3D-navigation system in a suitcase.

OBJECTIVE: To reduce the impact of contemporary 3D-navigation systems on the environment of typical otorhinolaryngologic operating rooms, we demonstrate that a transfer of navigation software to modern high-power notebook computers is feasible and results in a practicable way to provide positional information to a surgeon intraoperatively. MATERIALS AND METHODS: The ARTMA Virtual Patient System has been implemented on a Macintosh PowerBook G3 and, in connection with the Polhemus FASTRAK digitizer, provides intraoperative positional information during endoscopic endonasal surgery. RESULTS: Satisfactory intraoperative navigation has been realized in two- and three-dimensional medical image data sets (i.e., X-ray, ultrasound images, CT, and MR) and live video. CONCLUSIONS: This proof-of-concept study demonstrates that acceptable ergonomics and excellent performance of the system can be achieved with contemporary high-end notebook computers.

Humans↗
PubMed1999

Integrin-mediated signaling in human neutrophil functioning.

Integrins are important signal transducers for virtually all neutrophil functions. Although a variety of signals ultimately result in integrin activation, the intracellular targets of integrin-initiated signals are poorly delineated to date. Polymorphonuclear (PMN) leukocyte responses to inflammation are dependent on both the stimulants and the extracellular environment encountered. Integrin ligation, by cell-cell or cell-matrix interactions, activates a variety of signaling cascades. These events dictate the nature of PMN responses to the encountered stimulus. The complex system of effector molecule recruitment and permissive signaling by integrins serves to strictly regulate PMN functions such as cell adhesion, motility, oxidant production, and protein synthesis. Moreover, there is evidence that cross-talk between integrins exists to prime integrin populations for subsequent functioning. This review summarizes the current understanding of signaling mechanisms for integrin priming and activation. In this connection, the role of specific signaling molecules in key PMN functions are examined.

Humans↗