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PubMed2003

The roles of birth inputs and outputs in predicting health, behaviour and test scores in early childhood.

The goal of this study is to address directly the predictive value of birth inputs and outputs, particularly birth weight, for measures of early childhood development in a simultaneous equations modelling framework. Strikingly, birth outputs have virtually no structural/causal effects on early childhood developmental outcomes, and only maternal smoking and drinking during pregnancy have some effects on child height. Not surprisingly, family child-rearing environment has sizeable negative and positive effects on a behavioural problems index and a mathematics/reading test score, respectively, and a mildly surprising negative effect on child height. Despite little evidence of a structural/causal effect of birth weight on early childhood developmental outcomes, our results demonstrate that birth weight nonetheless has strong predictive effects on early childhood outcomes. Furthermore, these effects are largely invariant to whether family child-rearing environment is taken into account. Family child-rearing environment has both structural and predictive effects on early childhood outcomes, but they are largely orthogonal and in addition to the effects of birth weight.

Birth Weight↗

PubMed2006

Asymptotic extrapolation scheme for large-scale calculations with hybrid coupled cluster and molecular dynamics simulations.

In this paper we discuss a simple extrapolation scheme based on the asymptotic behavior of the electronic energies considered as functions of cutoff factor for orbital energies corresponding to virtual orbitals. The performance of this approach is illustrated in the context of large-scale dynamic simulations for excitation energies of the cytosine molecule in its native DNA environment. We demonstrate that the extrapolation errors are significantly smaller than the excitation-energy fluctuations, due to the fluctuating environment.

Journal Article↗

PubMedDate not supplied

Strengthening care for injured persons in less developed countries: a case study of Ghana and Mexico.

In all countries, the priority for reducing road traffic injuries should be prevention. Nonetheless, there are low-cost ways to strengthen the care of injured persons, that will help to lower the toll from road traffic. The purpose of this review was to elucidate ways to accomplish this goal in the context of less developed countries. Studies selected for this review were obtained by Medline review, selecting on key words such as trauma, injury, trauma care, essential health services, and developing country. Articles pertaining to any country and all available years were considered. In addition, the authors utilized articles from the gray literature and journals from Mexico and Ghana that are not Medline referenced. Studies surveyed point to road safety and other forms of injury prevention, as well as prehospital care, as likely priorities for developing countries. Nonetheless, hospital-based improvements can contribute to decreases in mortality and, especially, decreases in disability. For both prehospital and hospital based care, studies revealed several critical weak points to address in: (1) human resources (staffing and training); (2) physical resources (equipment, supplies, and infrastructure); and (3) administration and organization. The 'essential services' approach, which has contributed to progress in a variety of fields of international health, needs to be developed for the care of the injured. This would define the trauma treatment services that could realistically be made available to virtually every injured person. It would then address the inputs of human resources, physical resources, and administration necessary to assure these services optimally in the different geographic and socioeconomic environments worldwide. Finally, it would identify and target deficiencies in these inputs that need to be strengthened.

Accidents, Traffic↗

PubMed1976

Relation of general activity in rats to environmental temperature.

The relation between ambient temperature and amount and pattern of wheel running was examined in four experiments, with a total of 88 adult male albino rats of the Sprague-Dawley strain, under conditions of 12-hr. light/12-hr. dark. While lowering of temperature from baseline of 21--25 degrees C to 4--7 degrees C most typically led to increased running, consistently reduced running characterized a substantial number of individuals, especially those with relatively high baseline scores. When comparison trials were run at 27 degrees C, reduced activity was recorded for virtually all subjects. As temperature was elevated above 27 degrees C, however, there was in most cases an upturn. At 34 degrees C, 24-hr. running scores tended to exceed baseline level for about half the animals, and running during the light 12 hr. of the day was above baseline for virtually all. Analysis of the temporal distribution suggests that the thermoregulatory reduction of activity, readily demonstrated at the moderately warm temperature, is complicated by efforts to escape as the environment becomes aversively hot. Failure of previous investigators to observe this is attributable in part to apparatus and recording differences. It is speculated that the pattern of response to extreme temperatures is closely related to the circadian fluctuation of internal temperature.

Animals↗

PubMed1995

Development of a local Physician Executive Leadership Program.

Dramatic changes are occurring at a rapid pace throughout the United States in virtually all aspects of health care delivery. Physicians, hospitals, consumer groups, and others are thus facing new and greater uncertainties and are forced to adapt to a continually shifting environment. Fundamental change of this magnitude has and will continue to result in the formation of new alliances and organizations within which physicians and others will be forced to function. To participate effectively in these processes of change and to maintain influence within these new organizations, physicians will need leadership and management skills. To address the challenges facing current physician leaders and the need to develop more effective leaders, Sharp HealthCare developed its Physician Executive Leadership Program. This article describes the program and summarizes some of the lessons learned regarding the training of physician executives and leaders in today's changing health care environment.

California↗

PubMedDate not supplied

[Health problems of the urbanized North (review)].

Industrial development of northern areas has caused changes in sociosanitary working and living conditions of the population. The indices of public health have become an integral criterion for the environmental situation. A complex approach must be used for ecological and sanitary assessments of the environment. Technogenic stress has lead to the appearance of adverse environmental factors against which the human body has produced no adaptive mechanisms; they may contribute to the development of virtually all diseases. The specific features of the North do not allow the experience accumulated in other regions of the country to be mechanically extended there. To lower the environmental concentration of pollutants will be beneficial to human health.

Adult↗

PubMed1993

[Extensive hearing loss and deafness in adults].

Hearing and understanding are two related, yet different processes. Hearing is the perception of sound. It can be of enormous value to patients with severely impaired hearing, as it facilitates acoustic orientation. An understanding of speech, however, remains virtually impossible for most of these patients. Nevertheless, early habituation to their acoustic situation makes lip-reading much easier, thus enabling conversations to be possible in good listening environments. Severely impaired patients, however, are still not in a position to follow conversation in larger groups. Even with hearing aids and the deployment of the latest technology, sufficient help is not always given. Before making a decision on the use of these technical aids, the ENT specialist should discuss the needs of the particular individual with the hearing-aid specialist. Provided that residual hearing can be used to understand speech with the help of a hearing aid, intracochlear implantation of an electronic prosthesis is not indicated. A cochlear implant is indicated when there is a complete hearing loss on both sides. Such a profound loss means that sufficient understanding of speech is no longer possible, even with the assistance of the latest hearing aids. For most adults, deafness is a postlingual phenomenon. Adults who were born deaf or who lost their hearing in childhood tend to be unsuitable for cochlear implantation. Up to the age of six years, however, children born deaf can benefit considerably from a cochlear implant. Children who are provided with a cochlear implant shortly after becoming deaf also have a good chance of being capable of learning and understanding speech.

Adult↗

PubMed1994

Reversal of chimera donor-to-host tolerance in a tolerogen-free environment. Evidence of a nondeletional mechanism.

Clonal deletion of self-antigen-reactive T cells is known to be a dominant mechanism for tolerance induction in animals with a normal immune system. This phenomenon is mediated intrathymically by macrophages and dendritic cells. Some recent data have shown that tolerance to antigens expressed on radio-resistant thymic stromal cells results in clonal anergy. This report considers tolerance to host antigens in murine H-2-incompatible chimeras (H-2d-->H-2k) where thymic stromal cells remained of the host origin while virtually all lymphoid cells were replaced by donor H-2d cells. To assess the mechanism responsible for donor-to-host tolerance induction and the possible role of tolerogens in this process, we transferred (H-2d-->H-2k) chimeric lymphoid cells into lethally irradiated H-2d mice (a murine environment free of host H-2k antigens). Engrafted chimeric cells restored immunocompetence of secondary recipients without inducing a graft-versus-host reaction. H-2k skin test-grafts performed four weeks later were acutely rejected (median survival time = 9 days versus 11 days in controls). These results indicate that (A) donor-type lymphocytes reactive to host antigens in (H-2d-->H-2k) chimeras are not deleted during tolerance induction; (B) the continuous presence of the H-2k tolerogens appears to be necessary for the maintenance of nonreactivity to these tolerogens; (C) the anamnestic-like response to the H-2k skin grafts suggests that, during tolerance induction, anti-host (anti-H-2k) memory cells developed, an interpretation consistent with the concept that tolerance can result from a powerful immune response.

Animals↗

PubMed2005

Cytotoxicity assessment of some carbon nanotubes and related carbon nanoparticle aggregates and the implications for anthropogenic carbon nanotube aggregates in the environment.

Nanotechnology and nanomaterials have become the new frontier world-wide over the past few years and prospects for the production and novel uses of large quantities of carbon nanotubes in particular are becoming an increasing reality. Correspondingly, the potential health risks for these and other nanoparticulate materials have been of considerable concern. Toxicological studies, while sparse, have been concerned with virtually uncharacterized, single wall carbon nanotubes, and the conclusions have been conflicting and uncertain. In this research we performed viability assays on a murine lung macrophage cell line to assess the comparative cytotoxicity of commercial, single wall carbon nanotubes (ropes) and two different multiwall carbon nanotube samples; utilizing chrysotile asbestos nanotubes and black carbon nanoaggregates as toxicity standards. These nanotube materials were completely characterized by transmission electron microscopy and observed to be aggregates ranging from 1 to 2 microm in mean diameter, with closed ends. The cytotoxicity data indicated a strong concentration relationship and toxicity for all the carbon nanotube materials relative to the asbestos nanotubes and black carbon. A commercial multiwall carbon nanotube aggregate exhibiting this significant cell response was observed to be identical in structure to multiwall carbon nanotube aggregates demonstrated to be ubiquitous in the environment, and especially in indoor environments, where natural gas or propane cooking stoves exist. Correspondingly, preliminary epidemiological data, although sparse, indicate a correlation between asthma incidence or classification, and exposure to gas stoves. These results suggest a number of novel epidemiological and etiological avenues for asthma triggers and related respiratory or other environmental health effects, especially since indoor number concentrations for multiwall carbon nanotube aggregates is at least 10 times the outdoor concentration, and virtually all gas combustion processes are variously effective sources. These results also raise concerns for manufactured carbon nanotube aggregates, and related fullerene nanoparticles.

Adolescent↗

PubMed2002

Virtual reality surgical simulation for lower urinary tract endoscopy and procedures.

BACKGROUND AND PURPOSE: To provide a realistic experience of lower urinary tract endoscopic procedures, we have developed and continue to expand a computer-based surgical simulator that incorporates a surgical tool interface with anatomic detail and haptic feedback. METHODS: Surface-based geometric data for the lower urinary tract were generated from the National Library of Medicine Visible Human dataset. The three-dimensional texture map of the surface geometry was developed from recorded endoscopic video procedures. Geometry and associated texture maps were rendered in real time using the Silicon Graphics Extreme Impacts program. The surgical interface device incorporated all normal ranges of motion and resistance that occur within an actual operative environment. The hands-on endoscopic device attached to the interface device was provided by Circon-ACMI, Inc. Urologic residents evaluated the program for correlation with actual endoscopic procedures. RESULTS: Texture-mapped digitized images provided a close anatomic similarity to actual videoendoscopic images. Virtual endoscopy of the lower urinary tract was reproducible and closely simulated actual visual and tactile endoscopic experience. CONCLUSIONS: Virtual reality surgical simulation is feasible for a variety of lower urinary tract procedures. This system coordinates visual perception with appropriate haptic feedback in both longitudinal and rotational axes. These types of procedures may be incorporated into future educational experiences for urologists to introduce new techniques and to provide documentation of surgical experience.

Adult↗

PubMedDate not supplied

The reality of virtual learning for nurses in the largest integrated health care system in the nation.

The health care network and hospital system within the Department of Veterans Affairs (VA), the Veterans Health Administration (VHA), provides employment to more than 56,000 nursing personnel and serves as clinical education site to countless other nursing and health professional students. Nurse administrators and educators are posed with the challenge of providing an environment in which each nurse is able to gain needed knowledge, learn new skills, and share and communicate this knowledge with other colleagues. The education of nurses improves the health status of veterans while also realizing individual professional enhancement. Regional and cultural diversity of the system present challenges to education, in both delivery and content. VHA's learning organizations, the Employee Education System and the Office of Special Projects, have maximized new technologies and information systems to provide innovative, virtual education opportunities, capitalizing on the benefits of informal and formal learning, thus moving VHA to the forefront in knowledge sharing and dissemination. The Virtual Learning Center, VA Knowledge Network, Learning Catalog, and VA Learning Online provide VHA's nurses with interactive, desktop virtual learning opportunities.

Computer-Assisted Instruction↗

PubMed1998

Comparison of conventional and virtual simulation for radiation treatment planning of malignant lymphoma.

PURPOSE: The exact coverage of the lymph nodes and optimal shielding of the organs at risk are necessary for patients with Hodgkin's disease or malignant lymphoma to guarantee a high cure rate and a low rate of late effects for normal tissue. The purpose of this study was to compare conventional simulation and blocking with virtual simulation in terms of coverage of the target volume and shielding of the organs at risk in this highly curative patient group. PATIENTS AND METHODS: In 10 patients diagnosed with Hodgkin's disease and 5 patients with a Non-Hodgkin lymphoma radiation treatment planning for a mantle field or para-aortic field with inclusion of the spleen was performed in a conventional manner and with virtual simulation. With conventional technique, irradiation portals were defined during fluoroscopy and shielding of the organs at risk was drawn onto the simulation films, based on the information from previous X-ray films, CT or MRI scans. For virtual simulation, contouring of the target volumes and organs at risk (e.g. the kidneys) and the definition of the irradiation portals were performed with the AcQSim software package on a VoxelQ workstation (Picker Inc.) This was done in a beam's eye view environment on a currently driven CT scan in the treatment position. Both irradiation portals were compared in terms of coverage of the target volume and shielding of the organs at risk. RESULTS: Planning of a mantle field in the conventional way resulted in an incomplete coverage of the right hilus in 4/15 cases and of the left in 1/15 cases, respectively. The spleen and the spleen hilus were not covered completely in 5/15 and 6/15 cases, respectively. The left kidney was adequately shielded in only two thirds (10/15) of the conventionally planned fields. The planning time required for virtual simulation was reduced for the patient, but was increased for the physician because of the more time consuming contouring procedure compared to conventional simulation. CONCLUSIONS: Virtual simulation based on CT scans for radiation treatment planning of malignant lymphoma gives more information about soft tissue structures than conventional treatment planning. Therefore, it allows a more precise coverage of the target volumes and better shielding of the organs at risk. However, the time required for the whole procedure is increased. This is justified because of the often highly curative intention when treating this group of patients.

Feasibility Studies↗

PubMed2001

Hairpin ribozymes with four-way helical junctions mediate intracellular RNA ligation.

Virtually all RNA-mediated reactions require transitions among alternative RNA conformations. The complexity of biological reactions can obscure specific conformational changes in vivo and important features of the intracellular environment are difficult to reproduce in vitro. However, simple RNA self-cleavage and ligation reactions offer a unique opportunity to measure the kinetics and equilibria of specific RNA conformational transitions directly in living cells. Hairpin ribozymes that incorporate the natural four-way helical junction self-cleave rapidly in vivo, but only when cleavage products dissociate rapidly. Cleavage rates fall when cleavage products remain bound in stable base-paired helices, providing evidence that bound products undergo re-ligation. These results provide the first detailed kinetic description of an intracellular ribozyme reaction that includes cleavage, ligation and product dissociation rates. Kinetic and equilibrium parameters measured in vivo correspond well, but not perfectly, with values measured for the same reactions in vitro under conditions that approximate an intracellular ionic environment.

Base Sequence↗

PubMed1993

Micromachining technology and biomedical engineering.

Medical science and clinical medicine include many microscopic environments. Recent micromachining techniques fit the microscopic environments and are applied to microsurgery, fiberscopic operation, micromanipulation, artificial organs, and drug delivery systems. Microactuators, microsensors, and micro mechanical parts will be prepared for such medical devices and techniques. Virtual reality, stereovision, and fiber imaging support handling of cells and small targets of living body. The paper reports some perspectives of microtechnologies in biomedical engineering.

Angioplasty, Laser↗

PubMed2006

Setting the space for sex: architecture, desire and health issues in gay bathhouses.

This aim of this study was to describe and compare the physical design, as well as the atmosphere of urban gay bathhouses, and reflect on how desire operates within these premises when it intersects with the bathhouse environment and health imperatives. Three bathhouses were studied for a total of 147 h of observation. Men's desire for other men has created a landscape of spaces (real and virtual) where sex takes place in parks, alleys, restrooms, rest stops, adult theatres, video arcades, bookstores, bars, gay bathhouses and finally, the Internet. Although the Internet is perceived as an easy way for encountering sexual partners, gay bathhouses remain the most popular and convenient way, for men having sex with men to meet for regular or casual sex. This paper presents the descriptive results of an ethnographic nursing study that took place in three gay bathhouses located in two Canadian metropolitan areas. Gay bathhouses offer patrons a space within which a wide range of interactions, sensations and pleasure can be experienced. This paper highlights the specific features of three gay bathhouses, compares settings according to their specific architectural features and related sexual activities, and finally, proposes some changes in light of certain health issues.

Anthropology, Cultural↗

PubMed2003

Review and re-analysis of domain-specific 16S primers.

The Polymerase Chain Reaction (PCR) has facilitated the detection of unculturable microorganisms in virtually any environmental source and has thus been used extensively in the assessment of environmental microbial diversity. This technique relies on the assumption that the gene sequences present in the environment are complementary to the "universal" primers used in their amplification. The recent discovery of new taxa with 16S rDNA sequences not complementary to standard universal primers suggests that current 16S rDNA libraries are not representative of true prokaryotic biodiversity. Here we re-assess the specificity of commonly used 16S rRNA gene primers and present these data in tabular form designed as a tool to aid simple analysis, selection and implementation. In addition, we present two new primer pairs specifically designed for effective "universal" Archaeal 16S rDNA sequence amplification. These primers are found to amplify sequences from Crenarchaeote and Euryarchaeote type strains and environmental DNA.

Archaea↗

PubMed2002

Vibration characteristics of ultrasonic scalers assessed with scanning laser vibrometry.

OBJECTIVES: Scanning laser vibrometry is a non-invasive method of accurately measuring the vibratory characteristics of oscillating objects. The aim of this study was to observe, using a scanning laser vibrometer (SLV), the vibration patterns of dental ultrasonic scaler tips and to assess the effects of water flow rate and power setting on these patterns whilst operating the tips in an unloaded environment. METHODS: A 30kHz ultrasonic scaler (TFI-10, Dentsply) was fixed in position and a laser beam from the SLV was focused onto the tip. The laser, guided by a virtual measurement grid, was scanned over the oscillating tip surface. Scans were taken with the laser beam perpendicular to the long axis of the front face of the tip. RESULTS: Oscillation frequencies and the displacement amplitude at the unconstrained end of the tip were measured for various power/water settings. Vibration nodal positions were recorded for the various settings and were found to occur approximately 4mm from the free end of the tip. At low and medium power settings, tip displacement amplitude was reduced by increased water flow. At high power settings, combined with a high flow rate, the water leaves the body of the instrument as a jet. This left the tip relatively unconstrained, allowing it to oscillate at increased displacement amplitudes. CONCLUSIONS: This study shows that the SLV is able to accurately characterise the movement of oscillating ultrasonic scaler tips. The tips are affected by power setting and water flow rates.

Analysis of Variance↗

PubMed2003

The well-worn route and the path less traveled: distinct neural bases of route following and wayfinding in humans.

Finding one's way in a large-scale environment may engage different cognitive processes than following a familiar route. The neural bases of these processes were investigated using functional MRI (fMRI). Subjects found their way in one virtual-reality town and followed a well-learned route in another. In a control condition, subjects followed a visible trail. Within subjects, accurate wayfinding activated the right posterior hippocampus. Between-subjects correlations with performance showed that good navigators (i.e., accurate wayfinders) activated the anterior hippocampus during wayfinding and head of caudate during route following. These results coincide with neurophysiological evidence for distinct response (caudate) and place (hippocampal) representations supporting navigation. We argue that the type of representation used influences both performance and concomitant fMRI activation patterns.

Adult↗