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PubMed2000

Genetic testing for ataxia in North America.

BACKGROUND: The Ataxia Molecular Diagnostics Testing Group was established to generate quantitative proficiency and outcomes data regarding molecular testing for the autosomal dominant cerebellar ataxias (spinocerebellar ataxia types 1 [SCA-1] through -3, -6, and -7, and dentatorubral-pallidoluysian atrophy) in North America. METHODS AND RESULTS: Twenty-four North American laboratories that offered diagnostic testing for one or more ataxia genes were initially identified through GeneTests (Children's Health Care System, Seattle, WA). Eighteen laboratories agreed to participate in the study, which consisted of completing a technical survey, clinical survey, and molecular proficiency test. One laboratory returned the completed surveys but did not perform the proficiency testing. Ten of 18 laboratories (56%) provided data on test volumes, and these laboratories collectively performed 2,240 tests; approximately 5% of the tests yielded a positive result (i.e., identification of a pathological trinucleotide (CAG) repeat expansion). In proficiency testing, 100% of the laboratories correctly genotyped all samples, and 93% of the laboratories were within 1 SD of the mean for sizing normal alleles (one repeat unit or less). Ninety percent of the laboratories were within 1 SD for sizing expanded alleles. CONCLUSIONS: Proficiency testing showed little difference between laboratories with respect to allele sizing. However, additional phenotype/genotype correlations are necessary to define CAG repeat-length descriptors for SCA-1, SCA-2, and SCA-7 alleles of intermediate size.

Alleles↗
PubMed1995

Paediatric perfusion practice in North America: an update.

In August 1994, an updated survey questionnaire was mailed to each paediatric open-heart surgery programme in North America as a follow-up to the 1989 paediatric survey. The survey requested demographic data, equipment selection criteria and specific perfusion techniques for paediatric patients. The earlier survey revealed a wide range of clinical practice. Data from the recent survey were compared with the 1989 survey to identify current programme demographics and trends in equipment use and techniques. Responses were received from 125 hospitals (110 active programmes and 15 programmes that do not perform paediatric open-heart surgery) for a response rate of 74%. Of the 110 active centres, 77 perform both adult and paediatric cardiac surgery, and 33 perform paediatric surgery exclusively. Forty-three centres reported that they perform paediatric cardiac transplantation, an increase from 35 centres in 1989. Total caseload increased by more than 8% per year from 1988 to 1994. In 1994, 18% of the patients were operated upon during the first month of life (versus 15% in 1989), and 46% were operated on during the first year of life (versus 45% in 1989). While the 1989 survey was characterized by a high degree of heterogeneity in equipment and techniques, the recent survey reveals a trend toward homogeneity among respondents. The use of membrane oxygenation and arterial line filtration has become universal, and there was an increase in the use of all types of safety devices in the cardiopulmonary bypass circuit.

Adolescent↗
PubMed2006

Orthodontic treatment need in an accredited graduate orthodontic center in north america: a pilot study.

AIM: To assess the objective orthodontic treatment needs of patients treated in an accredited Orthodontic Clinic in North America using a retrospective cross sectional study and the Dental Aesthetic Index (DAI). METHODS AND MATERIALS: One hundred pre- and post-treatment study models were randomly selected from the model storage facility of the clinic. Only the pre-treatment study models were assessed using the DAI. The pre-treatment and post-treatment ages for each case were noted as recorded on the corresponding study models. The range for the pre-treatment age was 10 to 52 years, and from 12 years, 4 months to 54 years for the post-treatment age range. The duration of treatment for each case was calculated by subtracting the pre-treatment age from the post-treatment age (range of treatment duration, 9 to 125 months). Descriptive statistics as well as chi-square statistics were employed to analyze the data. RESULTS: Fifteen cases had normal or minor malocclusions with no treatment or slight need for treatment. Definite malocclusions with treatment highly desirable accounted for 22 cases and severe malocclusion with treatment highly desirable was found in 16 cases. Forty-seven cases had handicapping malocclusion with treatment considered mandatory. While a statistically significant association (p<0.05) was found between duration of treatment and severity levels of malocclusion (DAI scores), the association between pre-treatment age and DAI scores was not significant (p > 0.05). CONCLUSIONS: Eighty-five percent of the study sample needed orthodontic treatment with different malocclusion severity levels, while 47% of the cases qualified for publicly subsidized treatment due to handicapping malocclusions. The association between duration of treatment and DAI score groups (malocclusion severity levels) was found statistically significant. It could be helpful for more clinic-based (demand populations) studies on treatment needs be undertaken across the globe using the DAI, at least for the purposes of comparison.

Adolescent↗
PubMed2006

West Nile virus epidemics in North America are driven by shifts in mosquito feeding behavior.

West Nile virus (WNV) has caused repeated large-scale human epidemics in North America since it was first detected in 1999 and is now the dominant vector-borne disease in this continent. Understanding the factors that determine the intensity of the spillover of this zoonotic pathogen from birds to humans (via mosquitoes) is a prerequisite for predicting and preventing human epidemics. We integrated mosquito feeding behavior with data on the population dynamics and WNV epidemiology of mosquitoes, birds, and humans. We show that Culex pipiens, the dominant enzootic (bird-to-bird) and bridge (bird-to-human) vector of WNV in urbanized areas in the northeast and north-central United States, shifted its feeding preferences from birds to humans by 7-fold during late summer and early fall, coinciding with the dispersal of its preferred host (American robins, Turdus migratorius) and the rise in human WNV infections. We also show that feeding shifts in Cx. tarsalis amplify human WNV epidemics in Colorado and California and occur during periods of robin dispersal and migration. Our results provide a direct explanation for the timing and intensity of human WNV epidemics. Shifts in feeding from competent avian hosts early in an epidemic to incompetent humans after mosquito infection prevalences are high result in synergistic effects that greatly amplify the number of human infections of this and other pathogens. Our results underscore the dramatic effects of vector behavior in driving the transmission of zoonotic pathogens to humans.

Animals↗
PubMedDate not supplied

Antiquity of arthritis: spondyloarthropathy identified in the Paleocene of North America. off.

OBJECTIVE: Determination of the antiquity of spondyloarthropathy by examining the fossil record. METHODS: Fossil collections from the Paleocene and Eocene of North America were systematically examined to determine the occurrence and population frequency of spondyloarthropathy. RESULTS: Spondyloarthropathy was present in three mammalian orders dated at 30 to 50 million years. The frequency was 13% to 50% in the affected genera. CONCLUSIONS: Erosive arthritis of the spondyloarthropathy variety is now documented to have originated at least 40 million years ago in the Paleocene.

Animals↗
PubMedDate not supplied

Portrayal of childhood cancer in English language magazines in North America: 1970-2001.

This article is a content and discourse analysis of the portrayal of childhood cancer in English language magazines in North America. In a unique specification of published research on the media portrayal of disease, magazines were divided into three market or audience groupings called (1) science, (2) news/special interest, and (3) other (women/teen/parenting/health). The predominate frames or discoursesin these three groups were compared and differences were found amongst them and discussed in the article. Considerable evidence suggests that people with cancer are stigmatized. In the analyzed media focused on children, those with cancer are highly idealized and stereotyped. On the one hand, this can be thought of as a very positive portrayal of children in this situation. Children are described as if they possess heroic and idealized character traits, appearances, social characteristics, and personalities. Possible links between this idealized, polarized, and biased portrayal of children with cancer and their documented experiences of stigma are discussed.

Adolescent↗
PubMed1981

Ceramic evidence for prehistoric Datura use in North America.

Striking similarities in the details of the medicinal and ceremonial use of the genus Datura are known over a wide area in aboriginal North America, especially in the region extending from the Southwestern United States to Southern Mexico and Guatemala. Over this same geographical area there have been found a number of ceramic forms bearing a marked resemblance to the distinctive spiny fruit characteristic of the North American species of this genus. These so-called "spiked" or "hobnailed" ceramic forms are thought to represent objects that were associated with Datura use in pre-historic times, and the occurrence of these forms in archaeology sites may be of cultural/historical importance.

Archaeology↗
PubMed1999

Armadillos exhibit less genetic polymorphism in North America than in South America: nuclear and mitochondrial data confirm a founder effect in Dasypus novemcinctus (Xenarthra).

Heterozygosity at eight nuclear enzymatic loci and mitochondrial DNA control region (D-loop) sequence polymorphism was compared between North and South American nine-banded armadillos (Dasypus novemcinctus: Xenarthra, Dasypodidae). All markers revealed a striking genetic homogeneity amongst Texas, Louisiana, and Mississippi individuals, vs. the usual level of polymorphism for the French Guiana population. This may reflect a founder effect during colonization of North America. Occurrence of polymorphism in the D-loop microsatellite motif of North American armadillos suggests a recent recovery of mitochondrial variability. Phylogeographic analyses using Dasypus kappleri as outgroup provides evidence for a clear separation between North and South American control region haplotypes.

Animals↗
PubMed1999

Antimicrobial resistance among clinical isolates of Streptococcus pneumoniae in North America.

From a historical perspective, the development of antibiotic resistance among Streptococcus pneumoniae isolates can be traced over the past 3 decades. In North America, penicillin-resistant pneumococci are now found in nearly all medical centers, but the prevalence of such strains varies by region and time period. In the United States, only approximately 75% of all pneumococci are fully susceptible to penicillin, 15% are intermediately susceptible, and approximately 10% are highly resistant. The latter are often multiply resistant to other unrelated drugs, which leaves few effective chemotherapeutic agents with which to treat serious infections caused by such strains. New approaches to therapy are needed to avoid further selection of antibiotic-resistant mutants; these include discontinuing inappropriate or unnecessary use of antibiotics.

Anti-Bacterial Agents↗
PubMed2001

The Radiological Society of North America's Medical Image Resource Center: an update.

The Radiological Society of North America (RSNA) has initiated a long-term project called the Medical Image Resource Center (MIRC). The overall goal of the effort is to create an on-line library of medical images and related information and to maintain and index a number of other medical image resources. The rationale for the project, a summary of the overall requirements and objectives, and a finally a brief description of the future plans for MIRC are presented.

Computer Systems↗
PubMed1986

Complications in arthroscopy: the knee and other joints. Committee on Complications of the Arthroscopy Association of North America.

A questionnaire was sent to members of the Arthroscopy Association of North America surveying complications in arthroscopic surgery of the knee and other joints. There were 395,566 arthroscopies reported including 375,069 knee arthroscopies, 14,329 shoulder arthroscopies, 4,478 ankle arthroscopies, 1,569 elbow arthroscopies, and 121 wrist arthroscopies. There were 2,215 complications reported. The overall complication rate was 0.56%. Specific procedures were surveyed for the first time. The complication rate reported for meniscal repair was 2.4%. The complication rate in anterior cruciate ligament (ACL) procedures (repairs and reconstructions) was 1.8%. The procedure with the highest complication rate was the anterior staple capsulorrhaphy of the shoulder (5.3%). Surgery in the subacromial space resulted in a complication rate of 0.76%. None of these complication rates included failures. As newer procedures are instituted into clinical practice that involve various joints, and are more technically demanding, the complication rate is increasing.

Anesthesia↗
PubMed2003

Evidence for bimodal hybrid zones between two species of char (Pisces: Salvelinus) in northwestern North America.

Dolly Varden (Salvelinus malma, Pisces: Salmonidae) and bull trout (Salvelinus confluentus) have widely overlapping, but largely parapatric ranges in watersheds in northwestern North America from Washington State to northern British Columbia. Genetic analysis of natural populations using diagnostic molecular markers revealed widespread local sympatry and hybridization with hybrids comprising 0-25% of the local samples. In a detailed analysis of hybridization using four nuclear DNA markers and mitochondrial DNA within the Thutade Lake watershed, northcentral British Columbia, hybrid genotypes constituted up to 9% of the population of juvenile char. There were significant deviations from Hardy-Weinberg, gametic, and cytonuclear equilibria, and local samples showed bimodal frequency distributions of genotypes. Pure parental and inferred backcross genotypes were most common, and F1 and F(n) hybrids were comparatively rare. Interspecific hybridization was asymmetrical, with most F1 hybrids (five of six) bearing S. confluentus mtDNA. The introgression of nuclear and mitochondrial alleles was asymmetrical, with S. confluentus mtDNA and Growth Hormone 2 introgressing into S. malma significantly more than either introgression of the three other nuclear loci, or introgression of S. malma alleles into S. confluentus. Substantial prezygotic isolation between the species likely depends on the large body size difference between them in sympatry: S. malma have small bodies and a stream resident life history (12-21 cm adult fork length at maturity), while S. confluentus are larger and adfluvial, i.e., they migrate to Thutade Lake where they grow to maturity before returning to tributary streams to spawn (40-90 cm at maturity). These traits may limit interspecific pairings because of size assortative pairing and size-dependent reproductive habitat use.

Animals↗
PubMed2005

Long-term trends in home advantage in professional team sports in North America and England (1876-2003).

Home advantage is quantitatively defined and calculated for each season since the start of the main professional sports in North America and England. Over 400,000 games are analysed. The leagues represented are the National League (1876-2002) and American League (1901-2002) for baseball, the National Hockey League (1917-2003) for ice hockey, the National Football League (1933-2002) for American football, the National Basketball Association (1946-2003) for basketball, and the four levels of professional football, formerly called the Football League, in England (1888-2003). Problems caused by unbalanced playing schedules are considered. The results are presented graphically to show long-term trends and sudden changes. The highest levels of home advantage for all sports were in their early years of existence. Home advantage in ice hockey, basketball and football in England has declined over the last two decades. In baseball there has been very little change over the last 100 years, with home advantage consistently lower than in other sports. There was a large drop in home advantage in football in England following the 7-year suspension of the league during the Second World War. The trends and changes provide some evidence that travel and familiarity contribute to home advantage, but little in support of crowd effects.

Baseball↗
PubMed2000

A year of remarkable growth for donor milk banking in North America.

In 1999, approximately 322,700 ounces of milk were processed and distributed by the 7 member banks of the Human Milk Banking Association of North America. One new bank opened, and 2 medical centers in the United States are considering opening donor banks. The majority of the recipients were preterm and sick infants, but milk was also ordered for older babies and for children with a variety of medical needs, including metabolic disorders, severe food allergies or feeding intolerance, short gut syndrome secondary to necrotizing enterocolitis, growth failure on formula, and intractable rotavirus, and during chemotherapy for cancer. Donor milk was also ordered for adopted infants who did not have medical problems and for some adult cancer patients. Member banks serum screened 770 potential donors. One donor was excluded for a positive Hepatitis C test, and 3 were excluded for positive HTLV results. Further confirmatory tests were negative for these 4 potential donors.

Female↗
PubMedDate not supplied

Neisseria meningitidis with decreased susceptibility to penicillin: report from the SENTRY antimicrobial surveillance program, North America, 1998-99.

The purpose of this study was to estimate the prevalence of Neisseria meningitidis with decreased susceptibility to penicillin (MIC, >0.06 microg/mL) in North America (NA). Antimicrobial susceptibility testing by Etest (AB BIODISK, Solna, Sweden) was performed on 53 invasive clinical isolates obtained from 11 SENTRY Antimicrobial Surveillance Program participants in NA (9 states, 2 provinces) during 1998-99. All strains were markedly susceptible to ciprofloxacin (MIC(90), 0.008 microg/mL) and cefotaxime (MIC(90), < or = 0.002 microg/mL). Only 54.7% were susceptible to trimethoprim-sulfamethoxazole (TMP/SMX) at < or = 0.5/9.5 microg/mL. One strain was resistant to rifampin (MIC, > 32 microg/mL) and 16 isolates (30.2%) were relatively resistant to penicillin with MICs ranging from 0.094 to 0.25 microg/mL. No beta-lactamase production was detected. The serogroup distribution was 40% Y, 28% B, 24% C, 2% W-135, and 6% of strains were nongroupable. The prevalence of N. meningitidis with decreased susceptibility to penicillin in NA appears higher than previous reports.

Anti-Bacterial Agents↗
PubMed2003

Lake sediments record large-scale shifts in moisture regimes across the northern prairies of North America during the past two millennia.

Six high-resolution climatic reconstructions, based on diatom analyses from lake sediment cores from the northern prairies of North America, show that shifts in drought conditions on decadal through multicentennial scales have prevailed in this region for at least the last two millennia. The predominant broad-scale pattern seen at all sites is a major shift in moisture regimes from wet to dry, or vice versa (depending on location), that occurred after a period of relative stability. These large-scale shifts at the different sites exhibit spatial coherence at regional scales. The three Canadian sites record this abrupt shift between anno Domini 500 and 800, and subsequently conditions become increasingly variable. All three U.S. sites underwent a pronounced change, but the timing of this change is between anno Domini 1000 and 1300, thus later than in all of the Canadian sites. The mechanisms behind these patterns are poorly understood, but they are likely related to changes in the shape and location of the jet stream and associated storm tracks. If the patterns seen at these sites are representative of the region, this observed pattern can have huge implications for future water availability in this region.

Canada↗
PubMed2004

Regional differences in rates of plant speciation and molecular evolution: a comparison between eastern Asia and eastern North America.

The eastern Asian (EAS)-eastern North American (ENA) floristic disjunction is one of the best-known biogeographic patterns in the Northern Hemisphere. Recent paleontological and molecular analyses have illuminated the origins of the biogeographic pattern, but subsequent diversification and evolution of the disjunct floras in each of the two continents after isolation remains poorly understood. Although similar in climate and floristic composition, EAS has twice as many species as ENA in genera occurring in both regions. Explaining such differences in species diversity between regions with similar environmental conditions (diversity anomalies) is an important goal of the study of the global patterns of biodiversity. We used a phylogenetic approach to compare rates of net speciation and molecular evolution between the two regions. We first identified EAS-ENA disjunct sister clades from ten genera (Asarum, Buckleya, Carpinus, Carya, Cornus, Hamamelis, Illicium, Panax, Stewartia, and Styrax) that represent diverse angiosperm lineages using phylogenetic analyses of ITS (internal transcribed spacer of nuclear ribosomal DNA) sequence data. Species richness and substitution rate of ITS between sister clades were compared. The results revealed a pattern of greater species diversity in the EAS counterparts. A positive relationship between species diversity and ITS substitution rate was also documented. These results suggest greater net speciation and accelerated molecular evolution in EAS. The data support the idea that a regional difference in net speciation rate related to topographic heterogeneity contributes to the diversity anomaly between EAS and ENA. The close relationship between rates of ITS evolution and species richness further suggests that species production may be directly linked to rate of nucleotide substitution.

Biodiversity↗
PubMed2001

A taxonomic review of the Ceratophyllus Curtis, 1832 of North America (Siphonaptera: Ceratophyllidae: Ceratophyllinae).

The 22 North American taxa assigned to the flea genus Ceratophyllus Curtis, 1832, are reviewed. All are parasites of birds and include 17 species in the nominate subgenus, 3 in Emmareus and 2 in Celeophilus. Keys to the subgenera are provided, distinguishing characters of the individual species are discussed and illustrated and the various aspects of distribution and host preferences are cited.

Animals↗