Students Teaching Students: Student-Led Ultrasound Curriculum in Medical School Education.

Introduction With the expanding use of point-of-care ultrasound throughout medical specialties for the rapid bedside assessment integral to patient care, medical schools have sought to incorporate ultrasound education into their curriculum. Second-year medical students (MS2s) at our institution met this demand by forming the Ultrasound Student Instructor Cadre (USSIC), a longitudinal ultrasound curriculum where MS2s teach first-year medical students (MS1s). The objectives of this study were to assess the ultrasound knowledge of medical students and their perceptions of ultrasound incorporation into their medical education.

Spatiotemporal patterns of mercury accumulation in lake sediments of western North America.

For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in sediments have increased, on average, four times (4×) from 1850 to 2000 and continue to increase by approximately 0.

Canada's Veterans independence program: a pioneer of "aging at home".

The Veterans Independence Program (VIP) was developed in the late 1970s to promote the independence and aging at home of Second World War veterans. This paper describes VIP's origins, core services and its service-delivery approach. It also summarizes program expenditures and client trends, presents the results of research studies of program impact and effectiveness and discusses lessons learned and best practices.

Health care management competencies: identifying the GAPs.

This study examines issues around health care management competencies, as perceived by senior managers. A combination of questionnaire survey, focus group and in-depth interview methods was used to ascertain views on the importance of various competencies, current competency levels and thus the deficiencies or "GAPs." GAPs are greatest at the frontlines, where managers are generally appointed from clinical roles.

A measure of daily distress in practising medicine.

Objective: Existing measures of stress either focus on burnout or frustration and fatigue factors, often referred to as job strain. The objectives of this study were to: establish a reliable measure of distress that is sensitive enough to identify job strain at lower levels of distress and risk of burnout at higher levels of distress; and document levels of distress among the major medical specialties and across varying patterns of clinical practice.

Methods: A stratified cross-sectional survey of physicians in Canada was conducted in 2004.

Changes in dual-task voice reaction time among elders who use assistive devices.

Purpose: Assistive devices are prescribed for a variety of reasons and have the obvious benefit of enhancing gait performance for some individuals. However, the use of an assistive device may make walking a more complex and cognitively challenging task. The purpose of this study was to use a dual-task voice reaction time (VRT) paradigm to examine the attentional demands of walking with an assistive device in a group of elderly adults.

Systemic effects of arctic pollutants in beluga whales indicated by CYP1A1 expression.

Cytochrome P450 1A1 (CYP1A1) is induced by exposure to polycyclic aromatic hydrocarbons (PAHs) and planar halogenated aromatic hydrocarbons (PHAHs) such as non-ortho polychlorinated biphenyls (PCBs). In this study, we examined CYP1A1 protein expression immunohistochemically in multiple organs of beluga whales from two locations in the Arctic and from the St. Lawrence estuary.

Persistent organic pollutants and metals in the freshwater biota of the Canadian Subarctic and Arctic: an overview.

Over 1999-2002, an extensive series of contaminant studies was conducted on freshwater biota of Canada's Arctic and Subarctic regions. The majority of inorganic contaminant studies focused on mercury and fish. While mercury concentrations were low in benthic feeding fish such as whitefish, predatory fish such as lake trout, pike, and walleye frequently had mercury levels which exceeded 0.

Elevated mercury concentrations in fish in lakes in the Mackenzie River Basin: the role of physical, chemical, and biological factors.

During the mid-1990s and through the early 2000s, researchers determined that elevated mercury concentrations were a common occurrence in predatory fish in many lakes in the Mackenzie River Basin (MRB), located in northern Canada. Here we present the results of studies investigating factors contributing to higher mercury concentrations in fish in many of these lakes. Twenty-two percent of lake trout, 33% of northern pike, and 50% of walleye populations had mean mercury concentrations >0.

A history of total mercury in edible muscle of fish from lakes in northern Canada.

Subsistence fishing has been an important source of food for Native People in northern Canada since prehistoric time. Measurements of the levels of mercury in edible muscle of northern fish have been undertaken for over three decades in efforts to evaluate the risks of consuming northern fish. This report summarizes the data obtained from 7974 fish of 25 species from sites distributed from the Yukon to Labrador.

Persistent organic pollutants and mercury in marine biota of the Canadian Arctic: an overview of spatial and temporal trends.

This review summarizes and synthesizes the significant amount of data which was generated on mercury (Hg) and persistent organic pollutants (POPs) in Canadian Arctic marine biota since the first Canadian Arctic Contaminants Assessment Report (CACAR) was published in 1997. This recent body of work has led to a better understanding of the current levels and spatial and temporal trends of contaminants in biota, including the marine food species that northern peoples traditionally consume. Compared to other circumpolar countries, concentrations of many organochlorines (OCs) in Canadian Arctic marine biota are generally lower than in the European Arctic and eastern Greenland but are higher than in Alaska, whereas Hg concentrations are substantially higher in Canada than elsewhere.

Concentrations of mercury in tissues of beluga whales (Delphinapterus leucas) from several communities in the Canadian Arctic from 1981 to 2002.

Beluga whales have been hunted for food by Native People in the Canadian Arctic since prehistoric time. Here we report the results of analyses of total mercury in samples of liver, kidney, muscle and muktuk from collections over the period 1981-2002. We compare these results with human consumption guidelines and examine temporal and geographic variation.

Modern and historical fluxes of halogenated organic contaminants to a lake in the Canadian arctic, as determined from annually laminated sediment cores.

Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210Pb and 137Cs, and analyzed for a variety of halogenated organic contaminants (HOCs), including polychlorinated biphenyls (PCBs), organochlorine pesticides, short-chain polychlorinated n-alkanes (sPCAs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). Dry weight HOC concentrations in Lake DV09 sediments were generally similar to other remote Arctic lakes. Maximum HOC fluxes often agreed well with production maxima, although many compound groups exhibited maxima at or near the sediment surface, much later than peak production.

Dietary accumulation and biochemical responses of juvenile rainbow trout (Oncorhynchus mykiss) to 3,3',4,4',5-pentachlorobiphenyl (PCB 126).

Juvenile rainbow trout (Oncorhynchus mykiss) (initial weights 2-5 g) were exposed to three dietary concentrations (0, 12.4 and 126 ng g(-1), wet weight) of a 14C-labelled 3,3',4,4',5-pentachlorobiphenyl (PCB 126) for 30 days followed by 160 days of clean food. We assessed bioaccumulation, histology (liver and thyroid) and biochemical responses (liver ethoxyresorufin-O-deethylase (EROD), liver vitamins (retinoids and tocopherol) and muscle thyroid hormone levels) along with growth and survival.

Historical contamination of Yukon Lake sediments by PCBs and organochlorine pesticides: influence of local sources and watershed characteristics.

PCBs and other persistent organochlorine (OC) pesticides were analyzed in sediment cores collected from six lakes in Yukon Territory and one in northern British Columbia, Canada, with the objective of establishing sources and historical trends of these contaminants. DDT was found to be the most prominent OC in the sediment profiles of most of the lakes. Maximum sigmaDDT levels (3.

Vitamin and thyroid status in arctic grayling (Thymallus arcticus) exposed to doses of 3,3',4,4'-tetrachlorobiphenyl that induce the phase I enzyme system.

Induction of phase I biotransformation enzymes is recognized as a hallmark response in fish exposed to coplanar PCBs. Depletions of vitamins A and E and disrupted thyroid hormone and glandular structure secondary to this induction have not yet been examined in an arctic fish species. Arctic grayling were exposed to a single oral dose of 0 (control), 10, 100 or 1000 ng 3,3',4,4'-tetrachlorobiphenyl (TCB) g(-1) bodyweight, a contaminant found in most arctic fish.

Mercury species in the liver of ringed seals.

Four types of mercury species, namely, methylmercury, organic mercury other than methylmercury, inorganic mercury, and insoluble mercury, deemed to be mercuric selenide (HgSe), were found in the liver of 45 ringed seals from the Canadian Arctic. On average, methylmercury, at 2%, made up the smallest fraction of the total mercury in the liver of these animals. Of the total mercury concentration in seal liver, 53% was insoluble mercury, estimated to be largely mercuric selenide.

Tests of the fidelity of lake sediment core records of mercury deposition to known histories of mercury contamination.

There has been recent controversy over the discrimination between natural and anthropogenic loadings of mercury to lakes. Sediment core profiles have been interpreted as evidence that inputs to lakes have increased. Some investigators have argued, however, that mercury may be sufficiently mobile in sediments to generate profiles that are misinterpreted as historical records.

Contaminants in the Canadian Arctic: 5 years of progress in understanding sources, occurrence and pathways.

Recent studies of contaminants under the Canadian Northern Contaminants Program (NCP) have substantially enhanced our understanding of the pathways by which contaminants enter Canada's Arctic and move through terrestrial and marine ecosystems there. Building on a previous review (Barrie et al., Arctic contaminants: sources, occurrence and pathways.

Methylmercury and total mercury in tissues of arctic marine mammals.

Concentrations of methylmercury, total mercury and selenium in marine mammal tissues were determined in liver, muscle, skin (muktuk) and blubber of belugas, ringed seals and narwhal, using atomic absorption and capillary gas chromatography with ECD detection. Mean MeHg levels in the types of tissues analysed, except blubber, generally exceeded the Canadian Federal Consumption Guideline for mercury in fish (0.5 micrograms/g wet wt.

High concentrations of toxaphene in fishes from a subarctic lake.

Concentrations of toxaphene and other organochlorine compounds are high in fishes from subarctic Lake Laberge, Yukon Territory, Canada. Nitrogen isotope analyses of food chains and contaminant analyses of biota, water, and dated lake sediments show that the high concentrations of toxaphene in fishes from Laberge resulted entirely from the biomagnification of atmospheric inputs. A combination of low inputs of toxaphene from the atmosphere and transfer through an exceptionally long food chain has resulted in concentrations of toxaphene in fishes that are considered hazardous to human health.

Implications of chemical contaminants for aquatic animals in the Canadian arctic: some review comments.

Chemical residue analyses have established beyond doubt that arctic ecosystems are contaminated with low concentrations of several contaminants. The sources of these vary, but for many, the principal source is atmospheric deposition as a result of widespread dispersal by air masses carrying materials from lower latitudes. The principal problem discussed here is how to determine whether there are biological implications associated with the contaminants.

Catalytic and immunochemical characterization of hepatic microsomal cytochromes P450 in beluga whale (Delphinapterus leucas).

Understanding the effects of environmental contaminants on cetaceans and other marine mammals will require information on the biochemistry of xenobiotic metabolism in these species. We characterized the hepatic microsomal cytochrome P450 system in beluga whales (Delphinapterus leucas) from the Canadian Arctic. The content of native P450 averaged 0.

Dietary 2,3,7,8-tetrachlorodibenzofuran in rainbow trout: accumulation, disposition, and hepatic mixed-function oxidase enzyme induction.

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to dietary 2,3,7,8-[3H]tetrachlorodibenzofuran (TCDF) (0.36 to 42.8 ng g-1) and accumulation, tissue distribution, biotransformation, and hepatic monooxygenase enzyme (MO) induction were studied.

Presence and implications of chemical contaminants in the freshwaters of the Canadian Arctic.

Hydrocarbons, stable organochlorines, metals and radionuclides are widespread in the freshwaters of the Canadian Arctic. Petroleum-associated hydrocarbon sources include natural seepage, wastes and effluents from exploration, production and refining at Norman Wells and spills. Hydrocarbons also originate from combustion of carbon-based fuels, generally at lower latitudes and then reach the Arctic with air movements.