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At least 937 records · Page 52Linked to original sources
PubMed2006

The incidence and anatomic site specificity of chromosomal translocations in primary extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in North America.

Several balanced translocations have been identified in extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) but there are few data regarding their frequency in different anatomic sites or the frequency of translocations involving BCL6 or kappa or lambda immunoglobulin light chain genes (IGK or IGL), particularly in patients from geographic regions other than Europe and Japan. One hundred thirty-three paraffin-embedded North American primary MALT lymphoma specimens from diverse anatomic sites were studied by fluorescence in situ hybridization (FISH) using probes for API2-MALT1, IGH-MALT1, IGH-BCL10, IGH-FOXP1, IGH, +/- centromeres 3, 7, 12, and 18, and a subset (n=74) were analyzed using FISH probes for IGK, IGL, and BCL6. Translocations were mutually exclusive and were detected in 26% of cases (17% API2-MALT1, 5% IGH-MALT1, 3% IGH-unknown translocation partner, and 1% IGH-BCL10). Aneuploidy was associated with IGH-MALT1 and IGH-BCL10 but only rarely with API2-MALT1. There was striking site specificity, with API2-MALT1 showing a marked predilection for lung and intestine, and IGH-MALT1 and IGH-BCL10 occurring almost exclusively in lung. Twenty-three percent of translocation-negative primary MALT lymphomas from diverse sites showed complete/partial trisomy 18. No MALT lymphomas with translocations involving IGK, IGL, BCL6, or FOXP1 were identified. This FISH panel detected cytogenetic abnormalities in half of all MALT lymphomas, and translocations arose preferentially in MALT lymphomas of the lung and gastrointestinal tract. Differences in incidence and anatomic site specificity of translocations between North American and non-North American cases may reflect geographic variability of infectious or other etiologic factors.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Genetic and morphological characterization of the Aedes (Ochlerotatus) dorsalis (Diptera: Culicidae) group in North America.

An examination of the electrophoretically detectable variation among the North American members of the Aedes (Ochlerotatus) dorsalis group revealed large genetic differences among all 4 species. At least 9 of 18 loci examined (50%) were diagnostic for each species pair. However, morphological variation observed among species was low. Only Aedes canadensis (Theobald) was separated readily from the other members of this group [Aedes dorsalis (Meigen), Aedes melanimon Dyar and Aedes campestris Dyar & Knab] in all life stages. Characters traditionally used to separate the remaining 3 species were less reliable. In the adult female, Ae. melanimon may be distinguished from Ae. campestris by the scaling patterns of the wings and abdomen, but Ae. dorsalis could not be distinguished reliably by these characters. Adults of Ae. dorsalis may be separated reliably from those of Ae. campestris and Ae. melanimon only by the length of the subapical tooth relative to the length of the tarsal claw. Ae. melanimon was identified in the larval stage by the short mesothoracic hair 1. Eight larval characters differed between Ae. dorsalis and Ae. campestris. However, the ranges of these characters overlapped and no character was truly diagnostic. Genetic variation within species was low as measured by average heterozygosity and Nei's genetic distance coefficients. No allozymes were diagnostic for coastal and inland populations of Ae. dorsalis, and the pattern of genetic differentiation within this species did not correspond to the geographic location of the populations examined. Therefore, the genetic data did not support the hypothesis that Ae. dorsalis represents a complex of 2 or more cryptic species.

Abdomen↗
PubMed1987

Self-help clearing-houses in North America: a survey of their structural characteristics and community health implications.

Self-help groups hold the potential for helping many people adjust to health difficulties and life stresses. Self-help clearing-houses represent a community-centred approach to developing and realizing this potential. Several papers describing specific clearing-houses have been published, but a comprehensive survey of these organizations has not yet been completed. This article reports the results of such a survey, in which a majority of existing North American clearing-houses participated. Clearing-houses were found to have evolved rapidly in the last ten years, to the point that they now provide an array of informational, educational, and consultative services to catchment areas that contain over 70 million people. Although clearing-houses offer a unique perspective on the self-help movement and may make important contributions to physical and mental health, they also face technical, philosophical, and funding issues. Considering their tenacity and the robust rate at which they are being established, however, it seems likely that these and other problems will be solved, and that clearing-houses will become an established feature of the human services landscape.

Attitude to Health↗
PubMed1995

Coexistence of several novel hantaviruses in rodents indigenous to North America.

Three genetically distinct members of the Hantavirus genus have been detected in Nevada rodents by RT-PCR and nucleotide sequence analysis. These include Sin Nombre (SN), El Moro Canyon (ELMC), and Prospect Hill (PH)-like viruses which are primarily associated with Peromyscus maniculatus (deer mouse), Reithrodontomys megalotis (western harvest mouse), and Microtus spp. (voles), respectively. Although this region of the United States is ecologically diverse, rodents infected with different hantaviruses appear to coexist in several different geographical and ecological zones. In two widely separated states, Nevada and North Dakota, PH-like viruses are present in three different species of vole. In addition, ELMC-like virus has been detected in both R. megalotis and M. montanus (mountain vole). SN virus is a cause of hantavirus pulmonary syndrome throughout much of the United States. SN virus RNA is found in 12.5% of P. maniculatus in Nevada and eastern California. Two lineages of SN virus coexist in this region and differ from SN viruses originally found in infected rodents in New Mexico, Arizona, and Colorado. These data show the complexity of hantavirus maintenance in rodents. Distinct hantaviruses or virus lineages can coexist either in different or the same rodent species and in either different or the same geographic or ecological zones.

Animals↗
PubMed2003

Genetic footprints of demographic expansion in North America, but not Amazonia, during the Late Quaternary.

The biotic consequences of climate change have attracted considerable attention. In particular, the "refugial debate" centers on the possible retraction of habitats to limited areas that may have served as refuges for many associated species, especially during glaciations of the Quaternary. One prediction of such scenarios is that populations must have experienced substantial growth accompanying climatic amelioration and the occupation of newly expanded habitats. We used coalescence theory to examine the genetic evidence, or lack thereof, for late Pleistocene refugia of boreal North American and tropical Amazonian mammals. We found substantial and concordant evidence of demographic expansion in North American mammals, particularly at higher latitudes. In contrast, small mammals from western Amazonia appear to have experienced limited or no demographic expansion after the Late Pleistocene. Thus, demographic responses to climate change can be tracked genetically and appear to vary substantially across the latitudinal gradient of biotic diversity.

Animals↗
PubMed2004

Sequence typing reveals extensive strain diversity of the Lyme borreliosis agents Borrelia burgdorferi in North America and Borrelia afzelii in Europe.

The genetic polymorphism of Borrelia burgdorferi and Borrelia afzelii, two species that cause Lyme borreliosis, was estimated by sequence typing of four loci: the rrs-rrlA intergenic spacer (IGS) and the outer-membrane-protein gene p66 on the chromosome, and the outer-membrane-protein genes ospA and ospC on plasmids. The major sources of DNA for PCR amplification and sequencing were samples of the B. burgdorferi tick vector Ixodes scapularis, collected at a field site in an endemic region of the north-eastern United States, and the B. afzelii vector Ixodes ricinus, collected at a similar site in southern Sweden. The sequences were compared with those of reference strains and skin biopsy isolates, as well as database sequences. For B. burgdorferi, 10-13 alleles for each of the 4 loci, and a total of 9 distinct clonal lineages with linkage of all 4 loci, were found. For B. afzelii, 2 loci, ospC and IGS, were examined, and 11 IGS genotypes, 12 ospC alleles, and a total of 9 linkage groups were identified. The genetic variants of B. burgdorferi and B. afzelii among samples from the field sites accounted for the greater part of the genetic diversity previously reported from larger areas of the north-eastern United States and central and northern Europe. Although ospC alleles of both species had higher nucleotide diversity than other loci, the ospC locus showed evidence of intragenic recombination and was unsuitable for phylogenetic inference. In contrast, there was no detectable recombination at the IGS locus of B. burgdorferi. Moreover, beyond the signature nucleotides that specified 10 IGS genotypes, there were additional nucleotide polymorphisms that defined a total of 24 subtypes. Maximum-likelihood and parsimony cladograms of B. burgdorferi aligned IGS sequences revealed the subtype sequences to be terminal branches of clades, and the existence of at least three monophyletic lineages within B. burgdorferi. It is concluded that B. burgdorferi and B. afzelii have greater genetic diversity than had previously been estimated, and that the IGS locus alone is sufficient for strain typing and phylogenetic studies.

Animals↗