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PubMed2000

Circulation patterns of group A and B human respiratory syncytial virus genotypes in 5 communities in North America.

Human respiratory syncytial virus (HRSV) is a major cause of serious lower respiratory tract illness in infants, young children, and the elderly. To characterize the circulation patterns of HRSV strains, nucleotide sequencing of the C-terminal region of the G protein gene was performed on 34-53 isolates obtained from 5 communities during 1 epidemic year, representing distinct geographical locations in North America. Phylogenetic analysis revealed that 5-7 HRSV genotypes, including 1 or 2 predominant strains, circulated in each community. The patterns of genotypes were distinct between communities, and less diversity was seen between strains of the same genotype within than between communities. These findings are consistent with HRSV outbreaks' being community based in nature, although transmission of viruses between communities may occur. Several strains are probably introduced or circulate endemically in communities each year, and local factors-possibly immunity induced by previous years' strains-determine which strains predominate during an HRSV season.

Child↗

PubMed1999

Characteristics of pathogens causing urinary tract infections in hospitals in North America: results from the SENTRY Antimicrobial Surveillance Program, 1997.

Urinary tract infection (UTI) is common and involves pathogens with changing susceptibility patterns. The SENTRY Antimicrobial Surveillance Program evaluates international pathogen incidence patterns to detect and manage the emergence of resistant strains. We describe the antimicrobial resistance patterns among 1617 pathogens recovered from UTIs during the third-quarter of 1997 in North America (United States and Canada), as part of this worldwide program. The isolates were tested against more than 50 antimicrobial agents (20 reported) by reference broth microdilution methods, and selected isolates were characterized by pulsed-field gel electrophoresis (PFGE) and automated ribotyping. The five most frequently isolated species were Escherichia coli (48.6%), Enterococcus spp. (13.7%), Klebsiella spp. (12.0%), Pseudomonas aeruginosa (6.2%), and Enterobacter spp. or Proteus mirabilis (3.8% each). For each nation, imipenem and cefepime produced the widest spectrum of coverage among the beta-lactams and amikacin was best among the aminoglycosides. For Gram-negative species, high resistance among beta-lactam antimicrobial agents was noted especially for various penicillins against E. coli (37.9% to 42.8%) and for the cephalosporins tested against enterococci (99.4% and 100%). Approximately 7.0% of enterococci in the USA were vancomycin-resistant (88% with Van A). P. aeruginosa provided the most consistent levels of resistance, but the following agents were most active against these organisms: amikacin (96.6 to 97.4% susceptible), tobramycin (89.5 to 100.0%), piperacillin/tazobactam (89.5 to 100.0%), piperacillin (89.5 to 96.6%), imipenem (89.7 to 92.1%), cefepime (77.6 to 89.7%), and ceftazidime (82.9 to 86.2%). E. coli (2.2 to 2.7%), K. pneumoniae (6.2 to 6.4%), and a single Enterobacter cloacae strain produced extended-spectrum beta-lactamases; and five other Enterobacter spp. were likely to have expressed chromosomally mediated (Amp C) Stably derepressed cephalosporinases with associated resistance to ceftazidime (16.7 to 21.2% resistance). These data demonstrated that several UTI isolates in SENTRY hospitals have high levels of resistance to various classes of antimicrobial agents with little evidence of clonal dissemination.

Anti-Bacterial Agents↗

PubMed2006

Background concentrations of 18 air toxics for North America.

The U.S. Clean Air Act identifies 188 hazardous air pollutants (HAPs), or "air toxics," associated with adverse human health effects. Of these air toxics, 18 were targeted as the most important in a 10-City Pilot Study conducted in 2001 and 2002 as part of the National Air Toxics Trend Sites Program. In the present analysis, measurements available from monitoring networks in North America were used to estimate boundary layer background concentrations and trends of these 18 HAPs. The background concentrations reported in this study are as much as 85% lower than those reported in recent studies of HAP concentrations. Background concentrations of some volatile organic compounds were analyzed for trends at the 95% confidence level; only carbon tetrachloride (CCI4) and tetrachloroethylene decreased significantly in recent years. Remote background concentrations were compared with the one-in-a-million (i.e., 10(6)) cancer benchmarks to determine the possible causes of health risk in rural and remote areas; benzene, chloroform, formaldehyde, and chromium (Cr) fine particulate were higher than cancer benchmark values. In addition, remote background concentrations were found to contribute between 5% and 99% of median urban concentrations.

Air Pollutants↗

PubMed2005

Chiropractic in North America: a descriptive analysis.

OBJECTIVE: This paper provides descriptive data on chiropractors, their practice, and their patients in North America in the past decade. METHOD: Five sites in the United States and 1 in Canada were chosen, and a random sample of chiropractors was interviewed. In each practice, 10 patients were systematically selected on a single day. A total of 131 chiropractors and 1275 patients were interviewed. SUMMARY: The results suggest that doctors of chiropractic have firmly established themselves within the health care system in the United States and Canada and are able to attract patients who come to them directly for treatment, for largely back-related conditions, and who are willing to pay for their care.

Adult↗

PubMed2000

Ossification of the ligamentum flavum as a cause of myelopathy in North America: report of three cases.

Myelopathy caused by ossification of the ligamentum flavum is a rare condition in North America. The authors describe three patients whose myelopathy was attributed to posterior cord compression warranting laminectomy to decompress the cervical spine (in one patient) and the thoracic spine (in two patients). The spinal computed tomographic scan (especially after myelography) can be instrumental in guiding the management of this condition.

Aged↗

PubMed1997

Twenty-five years of obstetric patient satisfaction in North America: a review of the literature.

The North American literature on obstetric patient satisfaction of the past 25 years was reviewed using two major computerized databases. The articles identified by these searches were supplemented with other research articles identified in reference lists. The review highlights the difficulties inherent in the use of many different methodologies to study obstetric patient satisfaction. The main methodologies have been mailed questionnaires, telephone interviews, and semistructured interviews, with data collection periods ranging from 24 hours to 2 years postpartum. The various approaches to data collection make comparison of results among studies exceedingly difficult. The reluctance of patients to criticize their caregivers has been problematic and is evidenced by satisfaction ratings that are positively skewed. Factors that have been reported to be most influential in obstetric patient satisfaction include communication, control, participation in decision making, presence of a support person, information/prenatal classes, nursing care services, length of stay, and physical environment. The relative importance of these factors, however, has not been ascertained.

Communication↗

PubMed1995

Borrelia burgdorferi DNA is undetectable by polymerase chain reaction in skin lesions of morphea, scleroderma, or lichen sclerosus et atrophicus of patients from North America.

BACKGROUND: Borrelia burgdorferi has been linked to the pathogenesis of morphea and lichen sclerosus et atrophicus (LSA). However, considerable controversy still exists as to the actual role, if any, that this spirochete plays in the development of these diseases. Antibody titer determinations have been inconclusive and polymerase chain reaction (PCR) studies have yielded conflicting results. OBJECTIVE: We sought to show whether PCR analysis detected B. burgdorferi in archival tissue specimens from the involved skin of 20 North American patients with morphea, 10 patients with LSA, and four patients with scleroderma. METHODS: We used two different sets of PCR primers for the B. burgdorferi flagellin gene, one specific for European strains of B. burgdorferi, and another common to both European and American strains. A subset of these samples were further amplified with nested PCR primers. RESULTS: None of the samples showed PCR products with either primer sets, whereas purified B. burgdorferi DNA and lesional erythema chronicum migrans tissues, which were used as positive controls, yielded easily detectable products with all primer sets. CONCLUSION: These data suggest that B. burgdorferi infection plays no role in the development of morphea, LSA, or scleroderma in North American patients; these findings further support the recent observations that B. burgdorferi strain variability is associated with differential spectra of disease in North America compared with that found in various parts of Europe.

Borrelia burgdorferi Group↗

PubMed2004

Topographic, bioclimatic, and vegetation characteristics of three ecoregion classification systems in North America: comparisons along continent-wide transects.

Ecoregion classification systems are increasingly used for policy and management decisions, particularly among conservation and natural resource managers. A number of ecoregion classification systems are currently available, with each system defining ecoregions using different classification methods and different types of data. As a result, each classification system describes a unique set of ecoregions. To help potential users choose the most appropriate ecoregion system for their particular application, we used three latitudinal transects across North America to compare the boundaries and environmental characteristics of three ecoregion classification systems [Küchler, World Wildlife Fund (WWF), and Bailey]. A variety of variables were used to evaluate the three systems, including woody plant species richness, normalized difference in vegetation index (NDVI), and bioclimatic variables (e.g., mean temperature of the coldest month) along each transect. Our results are dominated by geographic patterns in temperature, which are generally aligned north-south, and in moisture, which are generally aligned east-west. In the west, the dramatic changes in physiography, climate, and vegetation impose stronger controls on ecoregion boundaries than in the east. The Küchler system has the greatest number of ecoregions on all three transects, but does not necessarily have the highest degree of internal consistency within its ecoregions with regard to the bioclimatic and species richness data. In general, the WWF system appears to track climatic and floristic variables the best of the three systems, but not in all regions on all transects.

Classification↗

PubMed2001

Current state of distance continuing medical education in North America.

BACKGROUND: Every continuing medical education (CME) provider is confronted one day or another with deciding whether to develop distance education programs that may enhance access to CME for health professionals. To make a judicious decision, one needs to understand the features of distance education and the experiences of other providers. METHODS: Since there was a lack of information in the literature regarding the actual state of distance CME in North America, a Web-based survey aimed at CME providers was conducted including a description of the providers, the users, the activities offered, the technologies employed, and the administration of the systems. RESULTS: The results from this study indicate that the majority (68%) of CME providers had not developed distance education programs at the time of the survey; 30% of the providers, mainly from private companies, were offering nondegree distance education programs, and 2% of the university providers were offering degree programs. The technologies mainly used to develop distance education programs were printed material (69%), videoconferencing (58%), and, to a lesser degree, videotape. The revenue sources to develop degree programs were government funding, tuition, and fees. Other sources such as commercial support and sales were used for nondegree programs. IMPLICATIONS: This study revealed that there was considerable interest in distance education, especially from the organizations not offering this type of program. Since distance CME features are now better known, this is a step toward the advancement and development of more and better distance education programs.

Education, Distance↗

PubMed2004

Patterns of mtDNA diversity in northwestern North America.

The mitochondrial DNA (mtDNA) haplogroups of 54 full-blooded modern and 64 ancient Native Americans from northwestern North America were determined. The control regions of 10 modern and 30 ancient individuals were sequenced and compared. Within the Northwest, the frequency distribution for haplogroup A is geographically structured, with haplogroup A decreasing with distance from the Pacific Coast. The haplogroup A distribution suggests that a prehistoric population intrusion from the subarctic and coastal region occurred on the Columbia Plateau in prehistoric times. Overall, the mtDNA pattern in the Northwest suggests significant amounts of gene flow among Northwest Coast, Columbia Plateau, and Great Basin populations.

Alaska↗

PubMed1980

Human nasopharyngeal carcinomas positive for Epstein-Barr virus DNA in North America.

Nasopharyngeal carcinomas (NPC) from 2 black patients and 1 Caucasian patient were positive for Epstein-Barr virus (EBV) DNA. Of the tumors, 2 were lymphoepitheliomas (undifferentiated NPC) and 1 was a moderately differentiated NPC. All 3 patients had high IgG titers against EBV early antigen and high IgG and IgA titers against virus capsid antigen (VCA). In one patient, the levels of anti-VCA IgA were different than those of anti-VCA IgG over the course of the disease. Our data support the association of EBV and NPC in North America.

Adolescent↗

PubMed2000

Phylogenetic, antigenic and clinical characterization of type 2 BVDV from North America.

Bovine viral diarrhea virus (BVDV) infection continues to have a significant impact upon US cattle producers despite the availability of more than 140 federally licensed vaccines. Detection and control is hampered by viral heterogeneity that results in differences in neutralizing epitopes, cytopathology and virulence. Recently it was found that there are two different genotypes, BVDV1 and BVDV2, among BVDV. BVDV2 isolates make up a significant proportion of the BVDV isolated in North America. Serologically BVDV2 viruses can be distinguished from BVDV1 and border disease viruses. Mab binding also distinguishes between BVDV1, BVDV2 and BDV. Like the BVDV1 viruses, BVDV2 viruses may exist as one of two biotypes, cytopathic or noncytopathic, based on their activity in cultured cells. Cytopathogenic effects on cultured cells does not correlate with virulence in vivo, as BVDV2 associated with hemorrhagic syndrome (HS) are noncytopathic. Variation among BVDV1 and BVDV2 in the 5' UTR is similar. Phylogenetic analysis and differences in virulence suggest that BVDV2 are heterogeneous. Symptoms resulting from BVDV2 infections may range from clinically inapparent to clinically severe. Recently, disease outbreaks associated with acute uncomplicated BVDV infection have been reported in the US and Canada. These outbreaks of clinically severe disease, termed HS, were all associated with viruses from the BVDV2 genotype. Not all BVDV2 isolates cause clinically severe disease. Avirulent BVDV2 isolates do exist and may predominate over virulent BVDV2 in nature. When virulent BVDV2 viruses are inoculated into calves they induce a disease characterized by fever, diarrhea, leukopenia, lymphopenia, neutropenia, thrombocytopenia, and death. Infection with avirulent BVDV2 results in a reduction of luekocytes that may be accompanied by a low-grade fever. These viruses do not cause clinical disease or a clinical leukopenia.

Animals↗

PubMed2002

Screening of ferritin light polypeptide 460-461InsA mutation in Parkinson's disease patients in North America.

An insertional (460-461InsA) mutation in the ferritin light polypeptide (FTL) gene was recently reported in some patients with a familial form of basal ganglia degeneration with varying extrapyramidal manifestations. Some of the affected family members presented with a phenotype indistinguishable from typical Parkinson's disease (PD). In this study, 253 patients with a clinical diagnosis of idiopathic PD were screened for the insertion in the FTL gene by polymerase chain reaction-restriction fragment length polymorphism method. The results showed that none of them had the mutation, indicating that genetic defects in the FTL gene are unlikely to be a common cause of typical PD, at least in a North America population.

DNA Mutational Analysis↗

PubMed2004

Chloroplast haplotype variation among monoecious and dioecious populations of Sagittaria latifolia (Alismataceae) in eastern North America.

Aquatic plants commonly have extensive geographical distributions, implying few restrictions to dispersal. Here we investigate the postglacial history of an aquatic plant with contrasting sexual systems (monoecy and dioecy), which are predicted to affect dispersal ability. We examined the distribution of cpDNA haplotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) among 76 populations (32 monoecious, 38 dioecious, two mixed and four undetermined populations) of Sagittaria latifolia sampled throughout eastern North America. We also use these data to investigate the polarity of the evolutionary transition between monoecy and dioecy. Using PCR-RFLP, we identified eight cpDNA haplotypes. All haplotypes were found in unglaciated areas of the species' range, clustered primarily in the southeastern United States, providing evidence that glacial refugia probably occurred in this area. Genetic diversity (hT) was more than six times greater among monoecious compared to dioecious populations. All seven of the haplotypes for which the sexual system could be determined were represented among monoecious populations. In contrast, only four haplotypes were detected in dioecious populations and 94% of individuals from dioecious populations possessed a single haplotype. Monoecious populations possessing this widespread haplotype were restricted to the southern portion of the range, indicating that dioecy probably originated in this region and then spread northwards. The distribution of cpDNA haplotypes in dioecious populations represents a subset of the variation found in monoecious populations, a pattern expected if dioecy has evolved from monoecy in S. latifolia.

Analysis of Variance↗

PubMed2004

Optimizing pharmacodynamic target attainment using the MYSTIC antibiogram: data collected in North America in 2002.

The OPTAMA Program is intended to examine typical antimicrobial regimens used in the treatment of common nosocomial pathogens and the likelihood of these regimens attaining appropriate pharmacodynamic exposure in different parts of the world. A 5,000-subject Monte Carlo simulation was used to estimate pharmacodynamic target attainment for meropenem, imipenem, ceftazidime, cefepime, piperacillin-tazobactam, and ciprofloxacin against Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. Standard dosing regimens from North America were used. Pharmacokinetic parameter variability was derived from existing healthy volunteer data, and MIC data came from the 2002 MYSTIC Program. Ciprofloxacin displayed the lowest target attainment against all bacterial species (41 to 46% for A. baumannii, 53 to 59% for P. aeruginosa, and 80 to 85% for the Enterobacteriaceae). Increasing the dose to 400 mg every 8 h did not significantly increase target attainment against nonfermenters. Piperacillin-tazobactam target attainments were similar to that of ceftazidime against all pathogens. Higher doses of both compounds were needed to achieve better target attainments against P. aeruginosa. Overall, meropenem, imipenem, and cefepime attained the highest probabilities of attainment against the Enterobacteriaceae (99 to 100%). The carbapenems appear to be the most useful agents against A. baumannii (88 to 92%), and these agents, along with higher doses of any of the beta-lactams, would be the most appropriate choices for empirical therapy for P. aeruginosa infection. Given the lack of agreement between percent susceptibility and probability of target attainment for certain antimicrobial regimens, a methodology employing stochastic pharmacodynamic analyses may be a more useful tool for differentiating the most-optimal compounds and dosing regimens in the clinical setting of initial empirical therapy.

Algorithms↗

PubMed2005

Twelve short tandem repeat loci Y chromosome haplotypes: genetic analysis on populations residing in North America.

A total of 2443 male individuals, previously typed for the 13 CODIS STR loci, distributed across the five North American population groups African American, Asian, Caucasian, Hispanic, and Native American were typed for the Y-STR loci DYS19, DYS385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438 and DYS439 using the PowerPlex Y System. All population samples were highly polymorphic for the 12 Y-STR loci with the marker DYS385a/b being the most polymorphic across all sample populations. The Native American population groups demonstrated the lowest genetic diversity, most notably at the DYS393 and DYS437 loci. Almost all of the 12-locus haplotypes observed in the sample populations were represented only once in the database. Haplotype diversities were greater than 99.6% for the African Americans, Caucasians, Hispanics, and Asians. The Native Americans had the lowest haplotype diversities (Apaches, 97.0%; Navajo, 98.1%). Population substructure effects were greater for Y-haplotypes, compared with that for the autosomal loci. For the apportionment of variance for the 12 Y-STRs, the within sample population variation was the largest component (>98% for each major population group and approximately 97% in Native Americans), and the variance component contributed by the major population groups was less than the individual component, but much greater than among sample populations within a major group (11.79% versus 1.02% for African Americans/Caucasians/Hispanics and 15.35% versus 1.25% for all five major populations). When each major population is analyzed individually, the R(ST) values were low but showed significant among group heterogeneity. In 692 confirmed father-son pairs, 14 mutation events were observed with the average rate of 1.57x10(-3)/locus/generation (a 95% confidence bound of 0.83x10(-3) to 2.69x10(-3)). Since the Y-STR loci reside on the non-recombining region of the Y chromosome, the counting method is one approach suggested for conveying an estimate of the rarity of the Y-haplotype. Because the Y-STR loci are not all in disequilibrium to the same extent, the counting method is a very conservative approach. The data also support that autosomal STR frequencies can be multiplied by the upper bound frequency estimate of a Y-haplotype in the individual population group or those pooled into major population groups (i.e., Caucasian, African American, Hispanic, and Asian). These analyses support use of the haplotype population data for estimating Y-STR profile frequencies for populations residing in North America.

Canada↗

PubMed2003

An Arctic mammal fauna from the Early Pliocene of North America.

A peat deposit on Ellesmere Island, Nunavut, Canada, allows a unique glimpse of the Early Pliocene terrestrial biota north of the Arctic Circle. The peat accumulated in a beaver pond surrounded by boreal larch forest near regional tree line in coastal hills close to the Arctic Ocean. The ecological affinities of the plant and beetle remains contained in the peat indicate that winter temperatures on Ellesmere Island were nearly 15 degrees C higher and summer temperatures 10 degrees C higher than they are today. Here we show that the mammalian remains buried in the peat represent mainly taxa of Eurasiatic zoogeographic and phyletic affinities, including the first North American occurrence of a meline badger (Arctomeles). This deposit contains direct evidence of the composition of an Early Pliocene (4-5 million years ago) arctic mammalian fauna during an active period of interchange between Asia and North America.

Animals↗

PubMedDate not supplied

Organ donation: what can we learn from North America?

The aim of this qualitative case study was to investigate how organ donation is promoted and managed in North America aimed specifically at patients and relatives. A 4-week study to Boston and Baltimore in America was undertaken to observe and learn how organ donation is promoted and managed within a critical care environment. The study tour was undertaken specifically to examine the policy and procedures that enhance the procurement of organ donation in specific centres in the USA. The study tour wanted to examine and gain a better understanding of the issues, policies and procedures used by these centres when seeking permission for organ donation. Data were collected by a variety of methods involving observation, unstructured informal interviews, examinations of policies and procedures and a daily diary was maintained. A thematic analysis method was used to analyse the qualitative data collected. Four areas were identified as potential areas for learning. Approaching relatives of potential donors for consent, at a time of intense emotional crisis, is a challenge that involves all nurses working in critical areas. Nurses are identified as a key component in the process of organ donation; research highlights that approaching relatives can be problematic and stressful for nursing staff. The British government should consider required request legislation that ensures all hospitals refer potential donors to the Regional Transplant Center. In-house coordinators could be appointed and protocols developed for referrals of potential donors. It is also suggested that the approach for consent is decoupled and designated requesters approach relatives.

Baltimore↗