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PubMed1975

Epidemic Venezuelan equine encephalitis in North America in 1971: vertebrate field studies.

Epidemic Venezuelan equine encephalitis in North America in 1971: vertebrate field studies. Am J Epidemiol 101:36-50, 1975.-In June 1971, epidemic Venezuelan equine encephalitis (VEE) invaded the lower Rio Grande Valley in south Texas. The Boca Chica area of Cameron County was selected as a study site to investigate vertebrate involvement in the natural cycle of epidemic VEE on the basis of considerable evidence of VEE virus activity there in equines, humans, and mosquito vectors. Only one VEE virus isolation was made from 4739 wild and domestic non-equine vertebrates, although numerous equine and human VEE virus isolations were made in concurrent studies. Serologic studies indicated that VEE virus activity was far greater in large domestic animals than in wild birds, wild mammals, or reptiles. Apparently epidemic VEE virus failed to establish itself in a wild vertebrate cycle in south Texas, since VEE antibody was found only in rabbits in 1972. Eventual cessation of VEE transmission in south Texas has been attributed 1) to the elimination of equines as a source of VEE virus by death, naturally acquired antibodies, or vaccination, 2) to quarantines, 3) to mosquito control, and 4) to the failure of epidemic VEE virus to become established in the wild vertebrate population. Equines emerge as the most important vertebrate host in the amplification and spread of virus during an epidemic of VEE.

Animals↗
PubMed1997

White pine blister rust control in North America: a case history.

White pine blister rust was introduced into North America at the turn of the twentieth century, threatening valuable white pine resources. Measures to eliminate, contain, or control this disease constitute the most extensive forest disease control effort in time, money, men, and materiel in the history of US forestry. The major thrust was protection of pine stands by eliminating currant and gooseberry (ribes) alternate hosts from within and around these stands. Failures with ribes eradication resulted in application of antibiotic fungicides without adequate testing. These failures, coupled with lower dependence on white pines and reduced need for a large reserve of men for fire fighting, led to sudden termination of the program in 1967. The chronology of events and interactions between agencies and personnel responsible for the program provide an interesting case history and, it is hoped, valuable lessons for the future.

Journal Article↗
PubMed2006

Air emission inventories in North America: a critical assessment.

Although emission inventories are the foundation of air quality management and have supported substantial improvements in North American air quality, they have a number of shortcomings that can potentially lead to ineffective air quality management strategies. Major reductions in the largest emissions sources have made accurate inventories of previously minor sources much more important to the understanding and improvement of local air quality. Changes in manufacturing processes, industry types, vehicle technologies, and metropolitan infrastructure are occurring at an increasingly rapid pace, emphasizing the importance of inventories that reflect current conditions. New technologies for measuring source emissions and ambient pollutant concentrations, both at the point of emissions and from remote platforms, are providing novel approaches to collecting data for inventory developers. Advances in information technologies are allowing data to be shared more quickly, more easily, and processed and compared in novel ways that can speed the development of emission inventories. Approaches to improving quantitative measures of inventory uncertainty allow air quality management decisions to take into account the uncertainties associated with emissions estimates, providing more accurate projections of how well alternative strategies may work. This paper discusses applications of these technologies and techniques to improve the accuracy, timeliness, and completeness of emission inventories across North America and outlines a series of eight recommendations aimed at inventory developers and air quality management decision-makers to improve emission inventories and enable them to support effective air quality management decisions for the foreseeable future.

Air Pollutants, Occupational↗
PubMed2002

The structure of diversity within New World mitochondrial DNA haplogroups: implications for the prehistory of North America.

The mitochondrial DNA haplogroups and hypervariable segment I (HVSI) sequences of 1,612 and 395 Native North Americans, respectively, were analyzed to identify major prehistoric population events in North America. Gene maps and spatial autocorrelation analyses suggest that populations with high frequencies of haplogroups A, B, and X experienced prehistoric population expansions in the North, Southwest, and Great Lakes region, respectively. Haplotype networks showing high levels of reticulation and high frequencies of nodal haplotypes support these results. The haplotype networks suggest the existence of additional founding lineages within haplogroups B and C; however, because of the hypervariability exhibited by the HVSI data set, similar haplotypes exhibited in Asia and America could be due to convergence rather than common ancestry. The hypervariability and reticulation preclude the use of estimates of genetic diversity within haplogroups to argue for the number of migrations to the Americas.

DNA, Mitochondrial↗
PubMed2003

Antimicrobial susceptibility profile among beta-haemolytic Streptococcus spp. collected in the SENTRY Antimicrobial Surveillance Program--North America, 2001.

The surveillance of antimicrobial resistance among beta-hemolytic Streptococcus spp. is an important health care concern due to the serious nature of the diseases that are caused by these pathogens and the emerging antimicrobial resistances. National and international studies have documented diverse rates of resistance to macrolide and lincosamide agents. The SENTRY Antimicrobial Surveillance Program evaluated the resistance rates of beta-hemolytic Streptococcus spp. to several drug classes including erythromycin and clindamycin during the 2001 study year. Twenty-five medical centers in North America contributed 787 isolates from serogroups A (SGA; 397 strains), B (SGB; 318 strains), G (SGG; 45 strains), C (SGC; 19 strains), and F (SGF; eight strains). Isolates were tested at a reference center by broth microdilution using NCCLS methods. A subset of isolates were characterized by molecular methods to determine the presence of erm and mef resistance mechanisms. All isolates were susceptible to beta-lactams, linezolid, vancomycin, chloramphenicol, quinupristin/dalfopristin, and fluoroquinolones. Garenoxacin (MIC(90,) 0.06 microg/ml) was the most potent fluoroquinolone tested. Tetracycline was inactive against SGB (14.8% susceptible) compared to SGC, SGG, SGF and SGA (48.9-85.6% susceptible). Resistance to erythromycin and clindamycin was highest among SGB isolates with M-phenotypes (mef) representing the majority (59.1%) of strains. Among isolates randomly selected for genotypic characterization, eight strains had mef (A), 16 had erm (A) [subclass erm (TR)], seven had erm (B) and one strain had erm (A) [subclass erm (TR)] and mef (A) present. These data when compared to previous SENTRY Program analysis showed macrolide resistance has remained stable over the last five years and M-phenotypes are the most prevalent expression of MLS(B) resistance in North America.

Anti-Bacterial Agents↗
PubMed1994

Trends in prevalence of dental fluorosis in North America.

This review of the literature was undertaken to demonstrate the changing trends in the prevalence of dental fluorosis in North America. Using Dean's early work to establish a baseline for the prevalence of dental fluorosis, results of more recent prevalence surveys were used to establish a range for the occurrence of dental fluorosis today. These results suggest that the prevalence of dental fluorosis now ranges somewhere between 35% and 60% in fluoridated communities and between 20% and 45% in nonfluoridated areas, depending on the influence of different local conditions. While the increase has occurred primarily in the very mild and mild categories of dental fluorosis, there is also some evidence that the prevalence is increasing in the moderate and severe classifications as well.

Adolescent↗
PubMed2005

More women in Europe and Australia have dental agenesis than their counterparts in North America.

DATA SOURCES: Medline and Embase were searched, using the following keywords: "hypodontia", "oligodontia", "anodontia", "agenesis", and "prevalence or incidence". Reference lists from retrieved articles were also examined. STUDY SELECTION: For inclusion, an article had to satisfy the following criteria: presence of an English abstract; the sample was representative for the underlying general population; the diagnosis of dental agenesis was based on a radiographic examination; the report presented information on the ethnic background; and the report presented prevalence of agenesis except third molars. DATA EXTRACTION AND SYNTHESIS: Data from Caucasian populations in North America, Australia and Europe were included in a meta-analysis. For the prevalence in African-American, Chinese and Arab groups, only indications could be reported because of a limited number of studies. Multiple-regression analysis was applied to evaluate the influence of chronological age, sample size, continent and year of publication. Statistical significance was established at P<0.05. The prevalence of agenesis per tooth type, affected patients and number of missing teeth per patient was calculated as far as reported in the papers. For the comparison of the prevalence for males and females, the relative risk (RR) was calculated. RESULTS: The search identified 141 articles, of which 31 met the inclusion criteria. Agenesis differs by continent and gender: the prevalence for both sexes was higher in Europe (males 4.6%; females 6.3%) and Australia (males 5.5%; females 7.6%) than for North-American Caucasians (males 3.2%; females 4.6%). In addition, the prevalence of dental agenesis in females was significantly higher than in males for all three continents, with an RR of 1.37 (95% CI, 1.28-1.45). The mandibular second premolar was the most affected tooth, followed by the maxillary lateral incisor and the maxillary second premolar. Unilateral occurrence of dental agenesis is more common than bilateral occurrence. Bilateral agenesis of maxillary lateral incisors is more common, however, than unilateral agenesis. In most patients, dental agenesis involved only one (48%) or two teeth (35%). CONCLUSIONS: The prevalence of dental agenesis in Europe and Australia is higher than in North America. The overall prevalence of agenesis in the maxilla is comparable with that in the mandible, but a marked difference was found between both jaws regarding tooth type. Absence of one or two permanent teeth is found in the majority of the subjects with dental agenesis.

Comment↗
PubMed2005

Coltiviruses and seadornaviruses in North America, Europe, and Asia.

Coltiviruses are tickborne viruses of the genus Coltivirus. The type species, Colorado tick fever virus (from North America), has been isolated from patients with flulike syndromes, meningitis, encephalitis, and other severe complications. Another coltivirus, Eyach virus, has been isolated from ticks in France and Germany and incriminated in febrile illnesses and neurologic syndromes. Seadornaviruses are endemic in Southeast Asia, particularly Indonesia and China. The prototype virus of the genus, Banna virus (BAV), has been isolated from many mosquito species, humans with encephalitis, pigs, and cattle. Two other seadornaviruses, Kadipiro and Liao Ning, were isolated only from mosquitoes. The epidemiology of seadornaviruses remains poorly documented. Evidence suggests that BAV is responsible for encephalitis in humans. Infection with BAV may be underreported because it circulates in regions with a high incidence of Japanese encephalitis and could be misdiagnosed as this disease.

Animals↗
PubMed1999

Species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae), parasites of coregonid and salmonid fishes from North America: taxonomic reappraisal.

A taxonomic study of species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae), from coregonid and salmonid fishes in North America, based largely on their type specimens, was carried out. None of the taxa studied possesses obvious autapomorphies that would justify its validity. On the contrary, all species share the following diagnostic features typical of Proteocephalus longicollis (Zeder, 1800) (syn. Proteocephalus exiguus La Rue, 1911), a polymorphic and widely distributed parasite in the Holarctic: (1) a spherical or club-shaped scolex, with sublaterally situated suckers and a vestigial but distinct and relatively large apical sucker; (2) the vagina possessing a well-developed vaginal sphincter and crossing mostly ventrally the proximal part of the cirrus sac; and (3) a long, thick-walled cirrus sac, overlapping vitelline follicles medially by more than its proximal half. Accordingly, Proteocephalus pusillus Ward, 1910; P. laruei Faust, 1920; "P. obtundus" La Rue, 1920 (nomen nudum); P. arcticus Cooper, 1921; P. wickliffi Hunter and Bangham, 1933; P. parallacticus MacLulich, 1943; P. californicus Haderlie, 1950; P. salmonidicola Alexander, 1951; and P. primaverus Neiland, 1952 are considered junior synonyms of P. longicollis.

Animals↗
PubMed2004

Biology and control of ticks infesting dogs and cats in North America.

At least 15 different infectious agents and diseases are transmitted or produced by ticks parasitizing dogs and cats in North America. Those infectious agents and diseases are distributed among eight different tick species that commonly infest dogs and cats. All but one of these species are hard ticks with a three-host development cycle in which each motile stage (larva, nymph, and adult) feeds on a different host after molting. Tick species, disease occurrence, and peak activity of each tick life stage can vary dramatically depending on geographic and climatic conditions. Gaining an understanding of tick distribution, tick ecology, and seasonal occurrence of different tick life stages can help with the management of tick infestations and reduce the incidence of tick-transmitted diseases in dogs and cats. Control should be based on an understanding and management of ecologic factors responsible for tick infestations and selection of appropriate acaricides. Occasionally, topical acaricides will appear not to have prevented tick infestations. This lack of control may be real or perceived based on reinfestation rates and/or pet owner expectations of product performance.

Animals↗
PubMed2004

Regionalized perinatal care in North America.

The aim of this article is to familiarize the reader with the status of regionalized perinatal health care in North America, and specifically in the United States of America, using the Iowa regionalization model. The evolution of the regionalization movement in the late 1960s and early 1970s is reviewed. It is noted that the movement was largely without federal government intervention. The role of the March of Dimes in developing the first set of so-called national guidelines is chronicled. The Iowa model, utilizing some non-tertiary referral centres, is discussed in depth. This model included extensive outreach education for the entire state, and worked well largely because of the lack of competition to the major university teaching hospital located at the University of Iowa in Iowa City. This was not true for many other states and regions because competition did exist between tertiary centres. The impact of managed care systems on the overall role of regionalization is discussed. Suggestions are offered for controlling the impact of third-party payers (managed care) on the quality of perinatal health care. An idealized system of monitoring the impact of regionalization and monitoring the effect of managed care is detailed. Finally, the future of regionalization is discussed in the face of deregionalization in populous areas. The need for the best possible care as close to patients' homes as possible (regionalization) still seems apparent.

Female↗
PubMed2000

'Candidatus Xenohaliotis californiensis', a newly described pathogen of abalone, Haliotis spp., along the west coast of North America.

Withering syndrome is a fatal disease of wild and cultured abalone, Haliotis spp., that inhabit the west coast of North America. The aetiological agent of withering syndrome has recently been identified as a member of the family Rickettsiaceae in the order Rickettsiales. Using a combination of morphological, serological, life history and genomic (16S rDNA) characterization, we have identified this bacterium as a unique taxon and propose the provisional status of 'Candidatus Xenohaliotis californiensis'. The Gram-negative, obligate intracellular pleomorphic bacterium is found within membrane-bound vacuoles in the cytoplasm of abalone gastrointestinal epithelial cells. The bacterium is not cultivable on synthetic media or in fish cell lines (e.g. CHSE-214) and may be controlled by tetracyclines (oxytetracycline) but not by chloramphenicol, clarithromycin or sarafloxicin. Phylogenetic analysis based on the 16S rDNA of 'Candidatus Xenohaliotis californiensis' places it in the alpha-subclass of the class Proteobacteria but not to the four recognized subtaxa of the alpha-Proteobacteria (alpha-1, alpha-2, alpha-3 and alpha-4). The bacterium can be detected in tissue squashes stained with propidium iodide, microscopic examination of stained tissue sections, PCR or in situ hybridization. 'Candidatus Xenohaliotis californiensis' can be differentiated from other closely related alpha-Proteobacteria by its unique 16S rDNA sequence.

Alphaproteobacteria↗
PubMed1988

Hepatic granuloma in a man from North America caused by a nymph of Linguatula serrata.

A calcified nodule on the liver of a 62-year-old man from North Carolina, USA, contained a degenerated nymph of Linguatula serrata. The nodule was incidentally discovered at laparotomy for malignant lymphoma and cholelithiasis. The cuticle was all that remained of the parasite, but sclerotized openings and large spines on the cuticle proved the parasite was L. serrata, a pentastomid arthropod. Anatomic location and size of the parasite indicated that it was consistent with the nymphal stage of L. serrata. This is the fifth confirmed infection of humans from North America by a pentastomid parasite.

Animals↗
PubMed1995

Alcohol consumption by orientals in North America is predicted largely by a single gene.

Orientals consume significantly less alcohol, and show a lower prevalence of alcohol abuse and dependence, than Caucasians. Sociological theories propose that this difference is due mainly to cultural factors. Physiological theories have suggested that the flushing reaction experienced by some Orientals serves as a deterrent to ethanol consumption. The flushing reaction is observed mainly in individuals who possess a mutation in the high-affinity aldehyde dehydrogenase (ALDH2) which renders the enzyme inactive. However, the tendency to flush correlates poorly with alcohol consumption, thus casting doubt on the physiological interpretations. The present study investigates the influence of the ALDH2 allele and of acculturation in North America on alcohol consumption by Orientals born in Canada or the United States. Oriental males carrying the inactive ALDH2(-) allele drink two-thirds less alcohol (6.1 +/- 1.5 vs. 18.2 +/- 2.8 drinks/4 weeks; p < 0.001), show one-third the prevalence of binge drinking (15.2 vs. 42.2%; p < 0.01), and are three times more likely to be abstainers (39.4 vs. 13.3%; p < 0.01) than Oriental ALDH2(+) males carrying the gene for the active enzyme. There were no significant differences in binge drinking or abstinence rates between ALDH2(+) Orientals and Caucasian males. Acculturation in North American society accounted for only 7-11% of the variance in overall consumption (p < 0.02). It is concluded that a single mutation in the high-affinity aldehyde dehydrogenase (ALDH2) gene predicts two-thirds of the alcohol consumption and excessive alcohol use by Oriental males born in North America.

Acculturation↗
PubMed2001

Phylogeography of the dusky shrew, Sorex monticolus (Insectivora, Soricidae): insight into deep and shallow history in northwestern North America.

Phylogenetic relationships among the dusky shrew (Sorexmonticolus) and eight related species (S. bairdi, S. bendirii, S. neomexicanus, S.ornatus, S. pacificus, S. palustris, S. sonomae and S.vagrans) were assessed using sequences from the mitochondrial cytochrome b gene (801 bp). Analyses using parsimony and maximum likelihood revealed significant molecular variation not reflected in previous morphological studies of these species. Conversely, three morphologically defined species (S.bairdi, S.neomexicanus and S.pacificus) were poorly differentiated. Sorexornatus and S.vagrans represented basal taxa for a more inclusive group that included: (i) a widespread Continental clade containing S.monticolus (Arizona to Alaska, including S. neomexicanus); (ii) a Coastal clade containing S.monticolus (Oregon to south-east Alaska, including S. bairdi and S. pacificus); (iii) the semiaquatic species (S. bendirii and S. palustris); and (iv) S.sonomae. Additional subdivision was observed within the Continental clade corresponding to populations from the northern and southern Rocky Mountains. Average uncorrected sequence divergence between the Coastal and Continental clades was 5.3% (range 4.5-6.2%), which exceeds many interspecific comparisons within this species complex and within the genus Sorex. Lack of resolution of internal nodes within topologies suggests a deep history of rapid diversification within this group. Late Pleistocene/Holocene glacial perturbations are reflected in the shallow phylogeographic structure within these clades in western North America. Our results suggest also that S. monticolus is not monophyletic under current taxonomic nomenclature. This perspective on phylogeographic history was developed within a growing comparative framework for other organisms in western North America.

Animals↗
PubMedDate not supplied

Assessing the potential impact of total disc arthroplasty on surgeon practice patterns in North America.

BACKGROUND CONTEXT: Intervertebral disc replacement has enjoyed a recent surge in popularity largely because of its anticipated release into the North American market. These devices offer an alternative to the 450,000 lumbar and cervical fusion procedures performed by US spine surgeons each year. The unanswered question at the present time is the potential impact, technologically and economically, of cervical and lumbar disc arthroplasty on the practice patterns of North American spine surgeons. PURPOSE: To assess the economic and societal impact of motion-sparing technology in the North American Market. SETTING: A review of the literature and an economic market analysis of the impact of intervertebral disc replacements on surgeon practice in North America. CONCLUSION: The potential economic effect of spine arthroplasty in the United States is staggering with conservative figures approximating $2.18 billion and 47.9% of the market share being captured by motion-sparing technology. Modeling spinal arthroplasty usage and influence after other spinal products, such as cylindrical cages and pedicle screws, may provide insight into the effects of motion-sparing technology. Regardless of the clinical outcome of disc arthroplasty, its potential economic impact will be significant.

Arthroplasty, Replacement↗
PubMed2005

Chloroplast DNA variation of Quercus rubra L. in North America and comparison with other Fagaceae.

Quercus rubra is one of the most important timber and ornamental tree species from eastern North America. It is a widespread species growing under variable ecological conditions. Chloroplast DNA variation was studied by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) in 290 individuals from 66 populations sampled throughout the natural range. A total of 12 haplotypes were detected, with one found in 75% of the trees. Population differentiation is relatively low (G(ST) = 0.46), even when similarities between haplotypes are taken into account (N(ST) = 0.50), pointing to a weak phylogeographical structure. Furthermore, no spatial structure of genetic diversity could be detected. The genetic differentiation increased northwards, reflecting the postglacial history of Q. rubra. The unusual aspect of this study was the low level of chloroplast DNA genetic differentiation in Q. rubra compared to that typically observed in other oak species. Palynological evidence indicates that during the last glacial maximum, Q. rubra had one major distribution range with populations located relatively far to the north, resulting in only modest movement northwards when climate improved, whereas European white oaks were largely restricted to the southern European peninsulas and experienced extensive movements during the postglacial period. The contrasted geographical features and levels of tree species richness of both continents might further explain why congeneric species sharing similar life history traits have genetic structures that are so different.

DNA, Chloroplast↗