THE IMPACT OF THE RADIOLOGICAL SOCIETY OF NORTH AMERICA, INCORPORATED.
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Forest losses predict bird extinctions in eastern North America.
Claims that there will be a massive loss of species as tropical forests are cleared are based on the relationship between habitat area and the number of species. Few studies calibrate extinction with habitat reduction. Critics raise doubts about this calibration, noting that there has been extensive clearing of the eastern North American forest, yet only 4 of its approximately 200 bird species have gone extinct. We analyze the distribution of bird species and the timing and extent of forest loss. The forest losses were not concurrent across the region. Based on the maximum extent of forest losses, our calculations predict fewer extinctions than the number observed. At most, there are 28 species of birds restricted to the region. Only these species would be at risk even if all the forests were cleared. Far from providing comfort to those who argue that the current rapid rate of tropical deforestation might cause fewer extinctions than often claimed, our results suggest that the losses may be worse. In contrast to eastern North America, small regions of tropical forest often hold hundreds of endemic bird species.
Journal Article↗
Spatiotemporal dynamics of Floerkea proserpinacoides (Limnanthaceae), an annual plant of the deciduous forest of eastern North America.
Because environmental filters are temporally and spatially heterogeneous, there often is a lack of significant relationship between the spatial patterns of successive life stages in plant populations. In this study, we determined the spatiotemporal relationships between different life stages in two populations of an annual plant of the deciduous forests of eastern North America, Floerkea proserpinacoides. Demographic surveys were done over a 4-yr period, and experiments were performed in the field and under controlled conditions to test for the effects of various environmental factors on population dynamics. There was a general lack of relationship between the spatial patterns of seed bank and seedling density, and a lack of similarity between their spatial correlograms. This was related mostly to the effects of spatially variable environmental filters operating on germination and emergence. However, environmental filters acting on plant survival were stable through time and contributed to stabilize the density and spatial patterns of the populations. Despite density-dependent presenescence mortality, spatial patterns of seedlings and mature individuals were similar and their correlograms were alike, suggesting that mortality did not fully compensate for density. Estimated fecundity was negatively correlated with population density over the study period. Although flower production started only 2-3 wk after emergence, seed maturation mostly occurred at the end of the life cycle, just before the onset of plant senescence. Yet, individual fecundity was low for an annual plant, i.e., 3.0 ± 0.5 mature seeds/plant (mean ± 1 SE). Seed predation by vertebrates was not significant. Low soil moisture had little effect on the total number of seeds germinating, although it slowed down the germination process. In quadrats where leaf litter was experimentally doubled, seedling emergence was lower than in control quadrats; in quadrats where leaf litter was completely removed, emergence did not differ from that in control quadrats. Susceptibility to drought stress was higher for seedlings than for mature plants. Although the species does not maintain a long-term persistent soil seed bank, other factors, such as density-dependent fecundity and autogamy, may temper population fluctuations through time and reduce the probability of local extinction.
Journal Article↗
[Primary health care and responsibilities of public health in 6 countries of Europe and North America: a pilot study].
BACKGROUND: Rapidly occurring changes within the health care systems are creating an opportunity to re-orient the relationships between their different sectors. In order to know the locus of responsibility for various types of preventive activities, we undertook an inquiry on eight areas in six countries from Europe and North America. METHODS: An inquiry among experts based on a matrix which arrayed the type of preventive health services against the target population. Eight clinical conditions were identified (childhood immunizations; adult influenza vaccination; mammography screening, tuberculosis screening, hypertension screening. PKU screening, HIV screening, and osteoporosis testing) trying to know their target population and the locus of responsibility for setting of policy, level to contact individuals for testing, follow-up of people with abnormal tests and maintenance of their medical records. RESULTS: This pilot study showed very little results coincidence either within the eight surveyed areas or across them. There was no regular pattern for the preventive activities studied among the different countries, neither according to the type of health system, nor to the primary health care orientation of the different systems. CONCLUSIONS: There was a limited consensus in the activities studied concerning the best mode of doing public health interventions for personal health services.
Canada↗
Diabetes, the ice free corridor, and the Paleoindian settlement of North America.
Since the 1940s, many Amerindian populations, including some with mixed Amerindian ancestry, have experienced an epidemic of obesity and adult-onset diabetes (NIDDM). Obesity and NIDDM were apparently rare among Amerindian populations prior to that time. Though the evidence is equivocal, obesity and NIDDM seem to be rare today among Athapaskan Amerindians of the North American Arctic, sub-Arctic, and Southwest. It is hypothesized that the Amerindian genotype(s) susceptible to obesity and NIDDM arose from selection favoring "thrifty" genes during the peopling of North America south of the continental glaciers. "Thrifty" genes (Neel: Am. J. Hum. Genet. 14:353-362, 1962) allowed a more efficient food metabolism as hunter-gatherers from an unusually harsh mid-latitude tundra environment (the "ice free" corridor) adapted to more typical mid-latitude environments to the south. The early Paleoindian settlement pattern from Wyoming to Arizona and Texas indicates a relatively brief period of reliance on unpredictable big game resources in lower elevations and smaller game and gathered resources in higher elevations. This unusual "specialist" settlement pattern may have resulted from the early Paleoindian's unfamiliarity with gathered foods and small game in lower elevations. Athapaskan populations evidently moved south from Beringia sometime after the Paleoindian migration when the "ice free" corridor had widened and contained environments and resources more typical of subarctic latitudes. Thus, Athapaskan hunter-gatherers could gradually adapt to the resources of lower latitudes such that "thrifty" genes would not have been as advantageous. The interaction of recently introduced "western" diets and "thrifty" genes have evidently led to today's epidemic of obesity and NIDDM among Amerindians of Paleoindian ancestry.
Canada↗
Multicenter trial in North America of UroLume urinary sphincter prosthesis.
We investigated the effectiveness and associated complications of treatment with an endoluminal urethral sphincter prosthesis in 153 spinal cord injury men (mean age 36 years, range 16 to 74 years) with urodynamically diagnosed detrusor-external sphincter dyssynergia. These patients were prospectively treated with a urethral sphincter stent at 15 centers in North America. Followup ranged from 2 to 33 months. Voiding pressures averaged 76 +/- 28, 42 +/- 21, 44 +/- 38, 35 +/- 18 and 32 +/- 20 cm. water, respectively, before prosthesis insertion in 153 patients and at 3 months in 123, 6 months in 114, 12 months in 98 and 24 months in 22. A significant decrease in voiding pressure was noted in the 22 patients at 24 months compared with matched preoperative data (80 +/- 25 cm. water, p = 0.03). The residual urine decreased from 181 +/- 154 ml. before insertion to 82 +/- 93 ml. at 24 months (p = 0.01). Maximum cystometric capacity remained constant, with a mean of 195 +/- 158 ml. before insertion to 248 +/- 122 ml. at 24 months (p = 0.17). No significant differences were apparent after 24 months of followup in any of the urodynamic parameters between 44 patients with and 109 without previous external sphincterotomy. Hemorrhage requiring blood transfusion, obstructive hyperplastic epithelial overgrowth and soft tissue erosion did not occur. No deleterious effects were observed on renal or erectile function. Of the patients 43 (28.1%) required 2 prostheses to bridge the external sphincter completely. Stent removal was required in 10 patients. Seven explantations were required for prosthesis migration, 1 for pain and urethral edema, 1 for inability to maintain a condom catheter, and 1 for nonepithelialization and secondary bladder neck obstruction. A total of 13 patients (8.5%) required a subsequent operation for bladder neck obstruction. Therefore, the sphincter prosthesis is an attractive modality for the treatment of external sphincter dyssynergia in patients with and without previous external sphincterotomy because of its ease of deployment and minimal associated morbidity.
Adolescent↗
Fire and insects in northern and boreal forest ecosystems of North America.
Fire and insects are natural disturbance agents in many forest ecosystems, often interacting to affect succession, nutrient cycling, and forest species composition. We review literature pertaining to effects of fire-insect interactions on ecological succession, use of prescribed fire for insect pest control, and effects of fire on insect diversity from northern and boreal forests in North America. Fire suppression policies implemented in the early 1900s have resulted in profound changes in forest species composition and structure. Associated with these changes was an increased vulnerability of forest stands to damage during outbreaks of defoliating insects. Information about the roles that both fire and insects play in many northern forests is needed to increase our understanding of the ecology of these systems and to develop sound management policies.
Journal Article↗
Phylogeographical lineages of Arctic grayling (Thymallus arcticus) in North America: divergence, origins and affinities with Eurasian Thymallus.
The number and location of Arctic glacial refugia utilized by taxa during the Pleistocene are continuing uncertainties in Holarctic phylogeography. Arctic grayling (Thymallus arcticus) are widely distributed in freshwaters from the eastern side of Hudson Bay (Canada) west to central Asia. We studied mitochondrial DNA (mtDNA) and microsatellite DNA variation in North American T. arcticus to test for genetic signatures of survival in, and postglacial dispersal from, multiple glacial refugia, and to assess their evolutionary affinities with Eurasian Thymallus. In samples from 32 localities, we resolved 12 mtDNA haplotypes belonging to three assemblages that differed from each other in sequence by between 0.75 and 2.13%: a 'South Beringia' lineage found from western Alaska to northern British Columbia, Canada; a 'North Beringia' lineage found on the north slope of Alaska, the lower Mackenzie River, and to eastern Saskatchewan; and a 'Nahanni' lineage confined to the Nahanni River area of the upper Mackenzie River drainage. Sequence analysis of a portion of the control region indicated monophyly of all North American T. arcticus and their probable origin from eastern Siberian T. arcticus at least 3 Mya. Arctic grayling sampled from 25 localities displayed low allelic diversity and expected heterozygosity (H(E)) across five microsatellite loci (means of 2.1 alleles and 0.27 H(E), respectively) and there were declines in these measures of genetic diversity with distance eastward from the lower Yukon River Valley. Assemblages defined by mtDNA divergences were less apparent at microsatellite loci, but again the Nahanni lineage was the most distinctive. Analysis of molecular variance indicated that between 24% (microsatellite DNA) and 81% (mtDNA) of the variance was attributable to differences among South Beringia, North Beringia and Nahanni lineages. Our data suggest that extant North American Arctic grayling are more diverse phylogeographically than previously suspected and that they consist of at least three major lineages that originated in distinct Pleistocene glacial refugia. T. arcticus probably originated and dispersed from Eurasia to North America in the late to mid-Pliocene, but our data also suggest more recent (mid-late Pleistocene) interactions between lineages across Beringia.
Analysis of Variance↗
A large terrestrial carbon sink in north america implied by atmospheric and oceanic carbon dioxide data and models
Atmospheric carbon dioxide increased at a rate of 2.8 petagrams of carbon per year (Pg C year-1) during 1988 to 1992 (1 Pg = 10(15) grams). Given estimates of fossil carbon dioxide emissions, and net oceanic uptake, this implies a global terrestrial uptake of 1.0 to 2. 2 Pg C year-1. The spatial distribution of the terrestrial carbon dioxide uptake is estimated by means of the observed spatial patterns of the greatly increased atmospheric carbon dioxide data set available from 1988 onward, together with two atmospheric transport models, two estimates of the sea-air flux, and an estimate of the spatial distribution of fossil carbon dioxide emissions. North America is the best constrained continent, with a mean uptake of 1.7 +/- 0.5 Pg C year-1, mostly south of 51 degrees north. Eurasia-North Africa is relatively weakly constrained, with a mean uptake of 0.1 +/- 0.6 Pg C year-1. The rest of the world's land surface is poorly constrained, with a mean source of 0.2 +/- 0.9 Pg C year-1.
Journal Article↗
Gastrointestinal parasites of cougars (Felis concolor) in Washington and the first report of Ollulanus tricuspis in a sylvatic felid from North America.
Gastrointestinal helminths including two species of cestodes (Taenia omissa and T. ovis krabbei) and three species of nematodes (Toxocara cati, Cylicospirura subequalis and Ollulanus tricuspis) are reported from two free-ranging cougars (Felis concolor) in Washington (USA). Ollulanus tricuspis is reported for the first time from cougars and represents the first occurrence of this parasite in a sylvatic felid from North America.
Animals↗
[Specialized tertiary care facilities for adults with congenital heart disease in North America and the United Kingdom: future directions in Japan].
Specialized tertiary care facilities have been established to care for the increasing numbers of adults with congenital heart disease. Because this cardiovascular subspecialty is relatively new, the dedicated facilities have evolved without preexisting guidelines. Therefore, a mini-review was conducted of specialized tertiary care facilities for adults with congenital heart disease in North America and the United Kingdom, to illuminate the future directions of continuous management of these patients in Japan. Specialized tertiary care was provided by integrated collaborative teams that involve medical and pediatric cardiologists, cardiac surgeons, and non-cardiac consultants. Continuing growth of this relatively new patient population and further evolution of specialized care facilities can be anticipated.
Adult↗
[The modeling of science: the example of North America].
Science is a complex human activity that is modeled by a myriad of factors beyond the researcher's control, especially in the medical sciences, where human and economic resources, as well as bioethical and regulatory factors play an important role. Bioethical and regulatory factors are similar between the US, Canada and Mexico, however these countries differ markedly in their economic and human resources: In Canada and the US there are government institutions (CIHR and NIH, respectively) to specifically provide funding to health research, while in Mexico the principal source of funding for all sciences is the National Council for Science and Technology (CONACYT). The NIH budget for clinical research alone during 2002 was over 7 US billion dollars; the CIHR funding for health research projects was approximately 300 US million dollars, while the support from CONACYT for research and infrastructure in health was aproximately 70 US million dollars. In the year 2000, the US had 8.17 researchers in all areas per 1,000 habitants--of the economically active population (EAP)--, Canada had 5.78 and Mexico 0.55 researchers. These factors impact greatly the scientific productivity: While Canada and the US contributed in 1991-1998 with 31.4% of the world's scientific productivity--measured as the number of articles published--, Latin America contributed with only 2.4% of the world's productivity. This paper also discusses other factors that model science, scientific inquiry, and scientific activity such as, the role of the industry, the media and scientific journals. How these factors influence the Medical Sciences in North America is exemplified herein.
Biomedical Research↗
The management of ductal carcinoma in situ in North America and Europe. Results of a survey.
BACKGROUND: The goal of the current study was to understand and document contemporary treatment approaches in the management of ductal carcinoma in situ (DCIS). METHODS: An original questionnaire was designed to assess radiation oncologists' management of breast carcinoma, including 26 questions specifically addressing DCIS. A postal survey was conducted of members of the American and European Societies of Therapeutic Radiology and Oncology. The results of 702 responses from North America were compared with 435 responses from Europe, to determine treatment recommendations and variability by type of institution and geographic region. RESULTS: There were strong correlations between the grade of DCIS and/or the margin status and the use of radiotherapy (RT; P < 0.0001). For Grade 3 DCIS, RT was recommended regardless of the margin status. Opinions were split in the treatment of low-grade DCIS with 10-mm margins. North American respondents were more likely to recommend RT for low-grade DCIS than their European counterparts (P < 0.0001). Within the United States, there were significant regional variations in physician recommendations for tamoxifen (P < 0.001), but not in the tendency to recommend RT. North American academic physicians were less likely to recommend RT for favorable DCIS than nonacademic physicians (P < 0.01). CONCLUSIONS: There were marked differences in physician opinions regarding the management of DCIS, with significant international differences in patterns of care. The survey quantified and highlighted areas of agreement and controversy regarding the use of RT and tamoxifen in the management of DCIS. It provided support for large international trials to evaluate the optimal management of DCIS in the areas identified as most controversial.
Breast Neoplasms↗
Malignant mesothelioma in North America.
Ascertainment, through 7,400 pathologists, of all fatal malignant mesothelial tumors in Canada (1960-75) and the U.S.A. (1972) gave a total of 668 cases (272 in 1972). In Canada, the annual number of male cases rose from about 17 in 1966 to 25 in 1972 but the number of female cases remained fairly steady at a much lower level. The annual incidence in North America in 1972 was estimated at 2.8 per million males and 0.7 per million females aged 15 years and over. Occupational histories were obtained "blind" for 480 of the 557 cases through 1972, and their matched controls; relative risks were as follows: insulation work, 46.0 asbestos production and manufacture, 6.1, heating trades (other than insulation) 4.4. For nearly half the male cases and for about 5% of female cases, the tumor could be attributed to occupational exposure to asbestos, of which a fifth were in shipyards. No indication was found of other possible causes (including man-made mineral fibers, tobacco smoking, or residence near zeolite deposits). Four subjects were men who had been employed in Quebec chrysotile mines and 3 were children of employees, but no other subject had lived in the mining area. The findings remain consistent with a much greater mesothelioma-producing potential for crocidolite and amosite than for chrysotile; however, further studies of factory workers exposed to chrysotile only are needed to confirm this. Mineral fiber analysis of lung tissue from patients and controls is in progress.
Adolescent↗
Brief communication: earliest cranial surgery in North America.
The archaeological evidence of ancient cranial surgery is limited to cases of trepanation and cauterization. I report here on the only known case of cranial surgery in direct association with the osseous image of a non-trauma-induced soft tissue lesion (sinus pericranii). This case, from Alameda County, California (Late Middle Period, ca. 300-500 AD), is the earliest and only definitive evidence of invasive surgery from prehistoric North America. Because this individual presents the only bony evidence of cranial surgery other than trepanation or cauterization, it contributes substantially to our extremely limited understanding of medical practices in preliterate societies.
Adult↗
Understanding levels and trends of BDE-47 in the UK and North America: an assessment of principal reservoirs and source inputs.
Despite increasing interest in the occurrence of Polybrominated diphenyl ethers (PBDEs) in the environment, there has been only limited effort expended to identify principal source input reservoirs and pathways into the environment. Taking a single congener BDE-47, an important component of the penta commercial product, we have estimated principal contemporary reservoirs and emissions in two regions with very different historical use patterns. In North America, production and use of the penta-product has been rising steadily for the last 20 years, whilst in the UK, use has been restricted over the last 10 years, and most recently, there has been an EU ban on use. Mass balance models have been applied using our contemporary emission estimates to predict environmental levels. Results highlight that contemporary emissions to air can account for contemporary air concentrations but cannot account for measured concentrations in principal reservoirs such as soils and sediments. Future efforts are needed to improve our knowledge of the stocks of PBDEs in use, and emission factors from those stocks, to better understand/predict past and likely future trends.
Environmental Exposure↗
Neuro-oncology research opportunities in North America: results of a survey by the AANS/CNS section on tumors.
OBJECTIVE: A primary goal of the AANS/CNS Section on Tumors is to foster neuro-oncology research. The Research Committee was charged with the responsibility of assessing the neuro-oncology research opportunities currently available within neurosurgery residency programs and proposing strategies to enhance these activities. METHODS: Two separate surveys were mailed to all neurosurgery program directors (112) and neurosurgery residents (872) in North America. The initial mailing was in December 1997 and a follow-up mailing was sent in June 1998 to those who did not respond. RESULTS: Seventy-seven (69%) program directors and 279 (32%) neurosurgery residents responded to the survey. Neuro-oncology research rotations of varying duration (usually <12 months) were available at most residency programs (87%). Research mentors included equal numbers of neurosurgeons and outside faculty. Funding sources were well distributed among departmental (27%), federal (24%), institutional (22%), and private (19%) sources. Common basic science research areas included molecular biology, gene therapy, and pathology, whereas image-guided surgery was the most frequent area of clinical research. Approximately one-third of the responding residents had completed a neuro-oncology research rotation, mainly in an area of basic science, which resulted in an average of two publications and three presentations at national meetings. The most significant challenges for residents pursuing neuro-oncology research were concurrent clinical responsibilities, lack of faculty mentors, and insufficient research funding. CONCLUSIONS: Neuro-oncology research opportunities are available within most neurosurgery residency programs and appear to attract a reasonable number of productive trainees. The results of this survey have identified several important ways in which the AANS/CNS Section on Tumors can enhance neuro-oncology research opportunities and a comprehensive strategy for accomplishing these goals is presented.
Data Collection↗
Dietary reference intakes: implications for fiber labeling and consumption: a summary of the International Life Sciences Institute North America Fiber Workshop, June 1-2, 2004, Washington, DC.
Multiple definitions of dietary fiber have been developed and are in use around the world. The definitions vary as to which substances are considered to be fibers, the analytical methods utilized to identify and measure these fibers, and whether physiological criteria are part of the definition. A workshop entitled "Dietary Reference Intakes: Implications for Fiber Labeling and Consumption" was held by the International Life Sciences Institute North America Technical Committee on Carbohydrates to review the fiber definitions recently published by the Institute of Medicine (IOM) of the National Academies. Presentations and facilitated discussions reviewed the rationale for the IOM definitions of dietary fiber, functional fiber, and total fiber in light of evolving nutritional science. Also discussed were potential analytical, regulatory, and consumer issues involved if the US Food and Drug Administration and/or Health Canada were to implement the IOM's recommendations. Issues, concerns, and questions to be addressed are summarized here.
Dietary Fiber↗