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PubMed2006

Persistent organic pollutants (POPs) as environmental risk factors in remote high-altitude ecosystems.

Persistent organic pollutants (POPs), and their transformation products, are the most investigated organic environmental contaminants within the past five decades. Organochlorines have been found in virtually all environmental compartments on the globe. Severe environmental implications have been shown to be associated with the presence of the POP group of contaminants in the environment. However, in the late 1990s, Canadian scientists first pinpointed the implication of POPs for high-altitude environments in a comprehensive way (Blais et al., 1998, Nature 395, 585-588). Under certain meteorological and geographic conditions, high-altitude environments can serve as "cold condensers" for atmospheric POP loadings. Subsequent investigations in high-altitude environments in Asia, Europe, and North and South America have confirmed suspicions that high-altitude mountainous regions have the potential to serve as focus regions for POPs and even for nonpersistent, medium-lived contaminants, such as "currently used pesticides", due to cold condensation and deposition in high altitudes. Although the presence and the altitude-dependent increase of POP levels in mountainous regions are confirmed by many international studies, the ecotoxicological consequences still remain largely unknown. At present, only a few studies have been published describing the biological effects in high-altitude environments due to increased POP exposure. Therefore, in this early stage of the international research effort on the ecotoxicological risk evaluation of persistent contaminants in high-altitude, pristine ecosystems, the present review intends to summarize the current state of research on POPs in high-altitude environments and draw preliminary conclusions on possible consequences of the presence of POPs in mountainous ecosystems based on currently available information from alpine and related Arctic environments.

Altitude↗

PubMed2004

A security architecture for interconnecting health information systems.

Several hereditary and other chronic diseases necessitate continuous and complicated health care procedures, typically offered in different, often distant, health care units. Inevitably, the medical records of patients suffering from such diseases become complex, grow in size very fast and are scattered all over the units involved in the care process, hindering communication of information between health care professionals. Web-based electronic medical records have been recently proposed as the solution to the above problem, facilitating the interconnection of the health care units in the sense that health care professionals can now access the complete medical record of the patient, even if it is distributed in several remote units. However, by allowing users to access information from virtually anywhere, the universe of ineligible people who may attempt to harm the system is dramatically expanded, thus severely complicating the design and implementation of a secure environment. This paper presents a security architecture that has been mainly designed for providing authentication and authorization services in web-based distributed systems. The architecture has been based on a role-based access scheme and on the implementation of an intelligent security agent per site (i.e. health care unit). This intelligent security agent: (a). authenticates the users, local or remote, that can access the local resources; (b). assigns, through temporary certificates, access privileges to the authenticated users in accordance to their role; and (c). communicates to other sites (through the respective security agents) information about the local users that may need to access information stored in other sites, as well as about local resources that can be accessed remotely.

Access to Information↗

PubMed2004

Information management in the emergency department.

Information system planning for the ED is complex and new to emergency medicine, despite being used in other industries for many years. It has been estimated that less than 15% of EDs have comprehensive EDIS currently in place. The manner in which administration is approached in large part determines the success in obtaining appropriate institutional support for an EDIS. Active physician and nurse involvement is essential in the process if the new system is to be accepted at the user level. In the ED, large volumes of information are collected, collated,interpreted, and acted on immediately. Effective information management therefore is key to the successful operation of any ED. Although computerized information systems have tremendous potential for improving information management, such systems are often underused or implemented in such a way that they increase the workload on caregivers and staff. This is counter productive and should be avoided. In developing and implementing EDIS one should be careful not to automate poorly designed manual processes. Examples are ED tracking systems that require staff to manually relocate patients in the system. This task probably is completed only when the ED volume is low and "worked around" when the department is busy. Information from such a system is, therefore, flawed; at best useless and at worst counter productive. Alternatively, systems are available that can track patients automatically through the ED by way of infrared sensors similar to those used in baggage-tracking systems that have been in place in airports for years. In the automated (computerized) ED, we must have zero-fault-tolerant,enterprise-wide, hospital information networked systems that prevent unnecessary duplication of tasks, assist in tracking and entering data, and ultimately help analyze the information on a minute-to-minute basis. Such systems only reach their potential when they are fully integrated, including legacy systems, rather than stand alone proprietary EDIS. Further,a modular approach in which individual components are connected to a flexible computer backbone is ideal.Finally, good clinical content is key to virtually every aspect of the EDIS. Much of this content is yet to be developed and what is available still needs to be adapted to the EDIS environment. Daunting as it may be, an EDIS implementation properly accomplished results in better patient care, improved staff productivity, and a satisfying work environment (Box 3).

Decision Support Systems, Clinical↗

PubMed1992

1H NMR studies on the catalytic subunit of aspartate transcarbamoylase.

The 1H NMR spectrum of the catalytic subunit of Escherichia coli aspartate transcarbamoylase (EC 2.1.3.2) was simplified by using strains auxotrophic for the aromatic amino acids and a growth medium containing fully deuterated Trp, Phe, and His and partially deuterated Tyr. 1H resonances for Tyr in the catalytic trimer (M(r) = 10(5)) were partially resolved into five peaks at 27 degrees C, which above 50 degrees C were further resolved to give a distinct resonance for each of the eight Tyr residues in the polypeptide chain. Experiments on chemically modified catalytic subunits and on a mutant form in which Tyr-165 was converted to Ser-165 led to the assignment of resonances for Tyr-165, Tyr-240, and Tyr-185. Binding of the substrate, carbamoyl phosphate, caused shifts of two of the unassigned resonances, and the subsequent binding of the aspartate analog succinate perturbed the resonances corresponding to Tyr-165 and Tyr-240. The bisubstrate analog N-(phosphonacetyl)-L-aspartate produced a spectrum differing considerably from that caused by the combination of carbamoyl phosphate and succinate. The NMR spectrum for the Tyr-165-->Ser mutant trimer showed clearly that the single amino acid substitution caused conformational changes affecting the environment of residues remote from the position of the replacement. In contrast, the inactive mutant subunit in which Gly-128 was replaced by Asp exhibited a spectrum virtually identical to that of the wild-type protein. However, addition of the substrate carbamoyl phosphate caused a marked change in the spectrum of the mutant enzyme, whereas that of the wild-type trimer was altered only slightly, showing that the effect of the amino acid substitution was manifested in the NMR spectrum only with the liganded enzyme.

Aspartate Carbamoyltransferase↗

PubMed2006

Chimeric plastid proteome in the Florida "red tide" dinoflagellate Karenia brevis.

Current understanding of the plastid proteome comes almost exclusively from studies of plants and red algae. The proteome in these taxa has a relatively simple origin via integration of proteins from a single cyanobacterial primary endosymbiont and the host. However, the most successful algae in marine environments are the chlorophyll c-containing chromalveolates such as diatoms and dinoflagellates that contain a plastid of red algal origin derived via secondary or tertiary endosymbiosis. Virtually nothing is known about the plastid proteome in these taxa. We analyzed expressed sequence tag data from the toxic "Florida red tide" dinoflagellate Karenia brevis that has undergone a tertiary plastid endosymbiosis. Comparative analyses identified 30 nuclear-encoded plastid-targeted proteins in this chromalveolate that originated via endosymbiotic or horizontal gene transfer (HGT) from multiple different sources. We identify a fundamental divide between plant/red algal and chromalveolate plastid proteomes that reflects a history of mixotrophy in the latter group resulting in a highly chimeric proteome. Loss of phagocytosis in the "red" and "green" clades effectively froze their proteomes, whereas chromalveolate lineages retain the ability to engulf prey allowing them to continually recruit new, potentially adaptive genes through subsequent endosymbioses and HGT. One of these genes is an electron transfer protein (plastocyanin) of green algal origin in K. brevis that likely allows this species to thrive under conditions of iron depletion.

Algal Proteins↗

PubMedDate not supplied

Clinical utility of three-dimensional US.

Three-dimensional (3D) ultrasonography (US) is rapidly gaining popularity as it moves out of the research environment and into the clinical setting. This modality offers several distinct advantages over conventional US, including 3D image reconstruction with a single pass of the US beam, virtually unlimited viewing perspectives; accurate assessment of long-term effects of treatment; and more accurate, repeatable evaluation of anatomic structures and disease entities. In obstetric imaging, 3D US provides a novel perspective on the fetal anatomy, makes anomalies easier to recognize, facilitates maternal-fetal bonding, and helps families better understand fetal abnormalities. Three-dimensional pelvic US allows volume data sets to be acquired with both transvaginal and transabdominal probes. Viewing multiple 3D power Doppler US images in a fast cine loop has proved useful in angiographic applications. Three-dimensional prostate US can help make accurate volume assessments for dosimetry planning or for estimating prostate-specific antigen levels. In breast imaging, 3D US has the capacity to demonstrate lesion margins and topography, thereby helping differentiate benign from malignant masses. Three-dimensional US can also help determine the need for biopsy and help facilitate needle localization and guidance during biopsy. With recent advances in computer technology and display techniques, 3D US will likely play an increasingly important role in medicine.

Biopsy↗

PubMed1995

Self-rotation estimate about the vertical axis.

The aim of this paper was to examine the accuracy of passive whole-body self-rotation estimate around the earth-vertical (yaw) axis. Subjects were required to reach an imposed angle of +/- 90 degrees, 180 degrees or 360 degrees (outward way), and then to rotate back to the initial position (return way), through passive rotation controlled by the subject, in darkness. During these rotations, only the semi-circular canals were stimulated. On the outward way, subjects were required to elaborate the correct imposed angle, without any external reference. In average, subjects undershot the expected angles on outward way, which suggests an overestimate of self-rotation, and the error increased with increasing expected angle. On the return way, subjects had to rotate back to the starting point, through a path integration process. There was no effect of the imposed angle on the error, and the variability was lower than on the outward way. The data suggests that the subjects could construct the internal representation of a virtual starting point: the initial body position, which became a goal to reach clearer than the outward rotation angle, which the subjects also have defined, in an environment deprived of any external spatial reference.

Adult↗

PubMed2004

Intraoperative stereoscopic QuickTime Virtual Reality.

OBJECT: The aim of this study was to acquire intraoperative images during neurosurgical procedures for later reconstruction into a stereoscopic image system (QuickTime Virtual Reality [QTVR]) that would improve visualization of complex neurosurgical procedures. METHODS: A robotic microscope and digital cameras were used to acquire left and right image pairs during cranial surgery; a grid system facilitated image acquisition with the microscope. The surgeon determined a field of interest and a target or pivot point for image acquisition. Images were processed with commercially available software and hardware. Two-dimensional (2D) or interlaced left and right 2D images were reconstructed into a standard or stereoscopic QTVR format. Standard QTVR images were produced if stereoscopy was not needed. Intraoperative image sequences of regions of interest were captured in six patients. Relatively wide and deep dissections afford an opportunity for excellent QTVR production. Narrow or restricted surgical corridors can be reconstructed into the stereoscopic QTVR mode by using a keyhole mode of image acquisition. The stereoscopic effect is unimpressive with shallow or cortical surface dissections, which can be reconstructed into standard QTVR images. CONCLUSIONS: The QTVR system depicts multiple views of the same anatomy from different angles. By tilting, panning, or rotating the reconstructed images, the user can view a virtual three-dimensional tour of a neurosurgical dissection, with images acquired intraoperatively. The stereoscopic QTVR format provides depth to the montage. The system recreates the dissection environment almost completely and provides a superior anatomical frame of reference compared with the images captured by still or video photography in the operating room.

Brain↗

PubMed2005

The VREST learning environment.

The VREST learning environment is an integrated architecture to improve the education of health care professionals. It is a combination of a learning, content and assessment management system based on virtual reality. The generic architecture is now being build and tested around the Lichtenstein protocol for hernia inguinalis repair.

Computer Simulation↗

PubMed2005

MobiDis: Toward a Patient Centric Healthcare Information System.

The paper presents some results of the MobiDis project. MobiDis is an information system that includes healthcare consumers and providers in a unique, virtual organisation aimed at promoting a patient centric paradigm in healthcare. It allows logons from desktop or laptop computers, as well as wireless PDAs or tablet PCs connected to Internet. In MobiDis the clinical data of each consumer are stored in the consumer's virtual healthcare record (VHR), a highly structured entity that exists on the network and is simultaneously updated with information from multiple locations. The MobiDis architecture creates an environment for VHRs by providing them with a large variety of services. In order to prove that our proposed architectural solution meets the project goals a prototype was developed. The paper describes the MobiDis architecture and the VHR services, and briefly presents the prototype.

Delivery of Health Care↗

PubMed1981

Characterization of conformational heterogeneity in the heme pocket of ferricytochrome c using high field proton nuclear magnetic resonance spectroscopy.

The proton nuclear magnetic resonance linewidth of a single hyperfine shifted heme methyl resonance in horse heart ferricytochrome c has been observed to show a strong increase upon decreasing the temperature (at neutral pH), increasing the pH (at 25 degrees C) or increasing the applied magnetic field, whereas the linewidth of an identical resonance in spectra of tuna heart ferricytochrome c is virtually independent of such changes. The mechanism producing this effect in the horse heart protein is consistent with exchange broadening due to rapid interconversion between heterogenous protein environments about this methyl. A detailed analysis of variable field and variable temperature studies indicates that the heterogeneity is highly localized about this methyl in horse heart cytochrome c and is absent in tuna heart cytochrome c. At -7 degrees C (with the addition of methanol), exchange between two environments is slow on the nmr time scale and a pH study under these conditions reveals that an amino acid with a pK of 7, previously undetected, controls the relative stability of the two environments. This methyl has been assigned to 3-CH3, indicating that the only amino acid side chain making contact with the methyl group, phenylalanine 82, must be able to exist in two nonequivalent positions. A comparison of cytochromes c from 11 species shows that those proteins having tyrosine in position 46 (such as tuna) do not exhibit field-dependent linewidths in any of the hyperfine shifted resonances, whereas those proteins with phenylalanine in position 46 all demonstrate this curious broadening.

Animals↗

PubMed1996

Grasping of virtual objects in changed gravity.

BACKGROUND: Little is known about the effects of changed gravity on the execution of grasping movements, even though such movements play an important role in normal motor behavior of humans. HYPOTHESIS: The formation of an adequate grip aperture is impaired in changed gravity. METHOD: During parabolic flight, five subjects grasped mirror-viewed virtual targets with their thumb and index finger. From their video-taped responses, we determined grip aperture as the distance between the two fingertips. RESULTS: In changed gravity, the final grip aperture was about 15% smaller than in normal gravity, and the peak grip aperture was about 30% less modulated by target size. Both findings were similar in hyper-G and in micro-G. CONCLUSIONS: We conclude that (virtual) grasping in changed gravity is affected by a deterioration of visual and/or proprioceptive signals, or by the increased computational burden of controlling movements in unusual force environments.

Adult↗

PubMed1997

Telecommunications and disease management in the home environment: new strategies to improve outcomes.

This article provides an overview of the issues and effects of principle-centered health care within organized systems of care; portrays a comprehensive disease management framework for home health care; and offers virtual health management, telecommunications, and mobile computing strategies to enable health management enterprises to achieve health and outcomes maximization accountability demands in managed care.

Disease Management↗

PubMed2003

The importance of the natural sciences to conservation: (an American Society of Naturalists symposium paper).

The last century has seen enormous environmental degradation: many populations are in drastic decline, and their ecosystems have been vastly altered. There is an urgent need to understand the causes of the decline, how the species interact with other components of the environment, and how ecosystem integrity is determined. A brief review of marine systems emphasizes the importance of natural sciences to understanding the systems and finding solutions. These environmental crises coincide with the virtual banishment of natural sciences in academe, which eliminate the opportunity for both young scientists and the general public to learn the fundamentals that help us predict population levels and the responses by complex systems to environmental variation. Science and management demands that complex systems be simplified, but the art of appropriate simplification depends on a basic understanding of the important natural history. It seems unlikely that meaningful conservation and restoration can be accomplished unless we recover the tradition of supporting research in and the teaching of natural history. We must reinstate natural science courses in all our academic institutions to insure that students experience nature first-hand and are instructed in the fundamentals of the natural sciences.

Conservation of Natural Resources↗

PubMed2002

Simulation of bleeding in endoscopic procedures using virtual reality.

BACKGROUND AND PURPOSE: An image-based approach has been developed to represent bleeding in a simulator for transurethral resection of the prostate (TURP). Whereas previous groups attempted to simulate bleeding mathematically over tissue surfaces or in blood vessels, our approach focused on macroscopic visualization of bleeding in a fluid environment. The TURP is an ideal procedure for simulator-based training because of its importance as a skill to acquire as well as its long learning curve. The most challenging step in creating a realistic TURP simulator is simulated bleeding. MATERIALS AND METHODS: We took an image-based approach in which we generated blood flow movies of bleeding vessels having different severity and position under variable fluid flow conditions and processed them to separate the blood flow from the background anatomy. We then organized the movies into a parametric database. During the running of the simulation, resection systematically triggers the playback of a blood flow movie (bleeding event). The movie is texture mapped onto a virtual surface that is positioned, oriented, morphed, composited, and looped into the virtual scene. RESULTS AND CONCLUSION: The technique produced an accurate depiction of bleeding vessels one would encounter during a TURP. The image changes readily according to the fluid flow state.

Blood Loss, Surgical↗

PubMed2000

Technical note: Stafne static mandibular bone defect-further expression on the buccal aspect of the ramus.

The anatomic distribution of the Stafne static mandibular bone defect (SSBD) is extended with a description of a cavitation defect on the buccal ramus of the mandible. The anatomical placement of SSBD thus correlates precisely with the submandibular and parotid salivary glands, and gives further evidence that an increase in major salivary gland size is associated with the defect. The global latitudinal variation in the population prevalence of SSBD ranges from 10% in the tropics to virtually 0% in most of the arctic. Globally the defect directly correlates with parasite load and diversity, and may be a marker for of a history of an environment with high levels of enteric macroparasite infestation.

Anthropology, Physical↗

PubMed1992

Differential transport and processing of variant mouse mammary tumor virus glycoproteins.

The transport and proteolytic processing of two individual gene isolates of the mouse mammary tumor virus (MMTV) glycoprotein were compared in transfected rat HTC hepatoma cells. Plasmids were constructed such that the MMTV glycoprotein genes were constitutively expressed from the promoter within the Rous Sarcoma Virus 5' Long Terminal Repeat in the absence of other MMTV proteins. An isolate of the GR strain MMTV glycoprotein was efficiently transported and processed resulting in the localization of MMTV glycoproteins at the cell surface and in the extracellular environment. Moreover, the kinetics of acquisition of endoglycosidase H resistant oligosaccharide side chains and the rate of endoproteolytic cleavage of the glycosylated polyprotein expressed in transfected cells were virtually identical to that observed in viral-infected rat hepatoma cells. In contrast, a natural variant of the C3H strain MMTV glycoprotein expressed in transfected cells was retained in an intracellular compartment by a heavy chain binding protein (BiP)-independent pathway in an endoglycosidase H sensitive and uncleaved form. This MMTV glycoprotein isolate was retained early in the exocytic pathway and displayed a half-life of approximately 45 min in transfected cells. Only a minor fraction of the expressed C3H variant glycoprotein was detected at the cell surface but was not externalized. Our results suggest that the variant C3H MMTV glycoprotein contains one or more mutations that preclude its efficient transport through the exocytic pathway.

Animals↗

PubMed1983

The effect of pH on the binding of sodium aurothiosulphate to human serum albumin. A possible binding mechanism.

The effect of pH on the binding of aurothiosulphate to human serum albumin was studied in unbuffered solutions at 37 degrees and ionic strength 0.15-0.16 M. In the investigated pH range, 6.3-8.4, the effect of pH on the high affinity association constant K1 was very different from that on the lower affinity constants K2-K4. K1 was virtually constant except for a two-fold decrease in the narrow pH range 7.5-7.9, which was explained as a H+ induced local conformation change in the environment of site 1. Contrary to this, K2-K4 decreased monotonically with increasing pH, which could be entirely accounted for by a change in electrostatic interaction. A conceivable binding mechanism consistent with the results might be: that gold binds as Au+ to the high affinity binding site by exchanging a H+ and that this site might be the free sulphydryl group in cysteine or the terminal alpha-amino group; and that gold binds as Au(S2O3)3-(2) to the lower affinity binding sites which might be the protonated basic side chain group, i.e. epsilon-amino groups.

Binding Sites↗