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At least 487 records · Page 27Linked to original sources
PubMed1982

Study of HLA alloantigens of the Navajo Indians of North America. II. HLA-A, B, C, DR and other genetic markers.

This report presents the antigen frequencies for HLA-A, B, C, DR, immunoglobulin, and red blood cell systems for the Navajo Indians of North America. HLA-A-B,B-C, and B-DR haplotype frequencies and significant delta values are given. These data are compared with similar data for other American Indians and major non-Indian ethnic groups. Very restricted HLA polymorphism is unique for the Navajo as well as American Indians in general and this feature has important implications with regard to disease association and transplantation.

Chromosome Mapping↗
PubMed1999

Gas exchange and carbon isotope discrimination of Juniperus osteosperma and Juniperus occidentalis across environmental gradients in the Great Basin of western North America.

We determined how ecophysiological characteristics of two juniper species, Juniperus occidentalis Hook. (western juniper) and Juniperus osteosperma (Torr.) Little (Utah juniper), changed along altitudinal and regional environmental gradients in the Great Basin of western North America. We obtained diurnal measurements of leaf gas exchange and xylem water potential (Psi) from plants at a low and a high altitude site within each of six mountain ranges during fall 1994, spring, summer, and fall 1995, and summer 1996. We also determined carbon isotope composition (delta(13)C) of leaf cellulose produced during the 1995 growing season. Overall, leaf gas exchange, Psi and delta(13)C did not differ significantly between species. Differences in daily (A(d)) and season-long (A(s)) carbon assimilation among mountain ranges suggested two groupings-a group of northern ranges and a group of southern ranges. Each group contained one mountain range with J. occidentalis and two with J. osteosperma. Differences in carbon assimilation based on this grouping were associated with two findings: (1) conductance of CO(2) from substomatal cavities to the site of carboxylation (g(m)) for junipers in the northern ranges averaged almost twice that of junipers in the southern ranges; and (2) physiological shifts occurred such that A(d) of junipers in the northern ranges was influenced more by Psi(pd), whereas A(d) of junipers in the southern ranges was influenced more by leaf temperature. Mean delta(13)C over all trees at a site was significantly correlated with annual precipitation. Significant differences in A(d) occurred between altitudes, but these differences were associated with differences in the timing of optimum leaf temperature for photosynthesis rather than with physiological acclimation to temperature, irradiance, or Psi. Most gas exchange parameters (e.g., assimilation, transpiration, stomatal conductance, and water use efficiency) varied seasonally, and the seasonal differences were strongly influenced by water stress.

Journal Article↗
PubMedDate not supplied

Geographic distribution of calcium pyrophosphate (CPPD) deposition disease in pre-Columbian North America: independent validation of CPPD criteria.

Calcium pyrophosphate deposition disease (CPPD), a form of crystalline arthritis, has a unique distribution in the Early to Middle Archaic Periods (3000 to 8000 years before the present) of North America, contrasting with the generalized geographic distribution of osteoarthritis. Incursion of CPPD into specific regions suggests possible migration patterns. The disparate geographic distribution of CPPD and osteoarthritis provide independent verification of the validity of diagnostic criteria utilized for the identification of CPPD.

Arthritis↗
PubMed2004

Implementing large-scale ENU mutagenesis screens in North America.

A step towards annotating the mouse genome is to use forward genetics in phenotype-driven screens to saturate the genome with mutations. The purpose of this article is to highlight the new projects in North America that are focused on isolating mouse mutations after ENU mutagenesis and phenotype screening.

Animals↗
PubMed2003

Field efficacy of ivermectin plus praziquantel oral paste against naturally acquired gastrointestinal nematodes and cestodes of horses in North America and Europe.

The efficacy of an oral formulation of ivermectin plus praziquantel in the reduction of nematode and cestode egg counts in horses was assessed in 273 horses under field conditions at 15 sites in North America (n = 6) and Europe (n = 9). Horses were confirmed by fecal examination to have natural infections of strongyles (100%) and tapeworms (76%). Replicates of four horses were formed at each site, and in each replicate three animals received ivermectin (0.2 mg/kg body weight) plus praziquantel (1 mg/kg body weight) oral paste and one animal remained untreated or received vehicle paste. Fecal samples were collected for fecal nematode and cestode egg counting before and 7, 8, 9, 14, 15, and 16 days after treatment. Horses treated with ivermectin plus praziquantel oral paste had significantly (P <.01) lower posttreatment strongylid and cestode egg counts (reductions of 98% or more) than controls. Combined site analyses revealed that 95% or 96% of the horses positive for cestode eggs before treatment that were treated with ivermectin plus praziquantel were negative for cestode eggs at each posttreatment fecal examination. No adverse reactions attributable to ivermectin plus praziquantel oral paste treatments were observed. The results of the studies demonstrated that ivermectin plus praziquantel paste was highly effective in reducing egg shedding by gastrointestinal nematodes and cestodes, and no adverse reactions were observed in horses treated under field conditions.

Administration, Oral↗
PubMed1999

The return of Cyclospora in 1997: another outbreak of cyclosporiasis in North America associated with imported raspberries. Cyclospora Working Group.

BACKGROUND: In the spring of 1996, an outbreak of cyclosporiasis associated with fresh Guatemalan raspberries occurred in the United States and Canada. Another multistate outbreak of cyclosporiasis occurred in North America in the spring of 1997. OBJECTIVE: To identify the vehicle of the outbreak that occurred in the spring of 1997. DESIGN: Retrospective cohort studies of clusters of cases associated with events (such as banquets) and traceback investigations of sources of implicated produce. SETTING: United States and Canada. PATIENTS: Persons who attended events associated with clusters of cases of cyclosporiasis. MEASUREMENTS: Identification of clinically defined or laboratory-confirmed cases of cyclosporiasis and risk factors for infection. RESULTS: 41 clusters of cases were reported in association with events held from 1 April through 26 May in 13 U.S. states, the District of Columbia, and 1 Canadian province. The clusters comprised 762 cases of cyclosporiasis, 192 (25.2%) of which were laboratory confirmed. In addition, 250 laboratory-confirmed sporadic cases were reported in persons who developed gastrointestinal symptoms from April through 15 June, for a total of 1012 cases. Fresh raspberries were the only food common to all 41 events and were the only type of berry served at 9 events (22.0%). Statistically significant associations between consumption of raspberry-containing items and cyclosporiasis were documented for 15 events (40.5% of 37). For 31 of the 33 events with well-documented traceback data, the raspberries either definitely came from Guatemala (8 events) or could have come from Guatemala (23 events). The mode of contamination of the raspberries remains unknown. The outbreak ended shortly after the exportation of fresh raspberries from Guatemala was voluntarily suspended at the end of May 1997. CONCLUSIONS: Similar multistate, multicluster outbreaks of cyclosporiasis associated with consumption of Guatemalan raspberries have occurred in consecutive years. These outbreaks highlight the need for better understanding of the biology and epidemiology of Cyclospora cayetanensis and for stronger prevention and control measures to ensure the safety of produce eaten raw.

Animals↗
PubMedDate not supplied

The artificial kidney in North America: George Murray and the Canadian connection.

Approximately 50 years after the Scottish chemist Thomas Graham described the process of selective diffusion in solutions (dialysis) in 1861, a Johns Hopkins University team led by John J. Abel purified animal blood using celloidin membranes. Termed "vividiffusion" by Abel, these limited but successful experiments were abandoned in 1914. The most successful artificial kidney machine was later devised by Willem J. Kolff in Holland during the early 1940s; this basic design later developed into a commercially successful venture in America. Other mechanical hemodialysis equipment was also invented, such as that of Canadian surgeon George Murray (1894-1976), who devised the first artificial kidney machine in North America in 1946. Blood to be filtered was gently pumped through a vertical helical coil of cellulose acetate tubing (the dialyzing membrane) placed in a salt-buffered tapwater solution. Four patients were treated in this manner, all of whose blood was purified; however, two of this group later died due to chronic kidney problems. Murray's artificial kidney was never developed commercially owing to Kolff's more efficacious design and, it is contended here, due to the failure of Canadians to capitalize on domestic technological innovations. It is also suggested that as it is an example of simultaneous invention, a further exploration of the artificial kidney might reveal insights into the historical development of modern medical technology.

Canada↗
PubMed1998

Epidemic mycoplasmal conjunctivitis in house finches from eastern North America.

In the winter of 1993-94, house finches (Carpodacus mexicanus) with severe conjunctivitis (later shown to be caused by Mycoplasma gallisepticum) were first observed in sub-urban Washington D.C. (USA) and adjacent states. Using a large network of volunteer observers in eastern North America, we were able to track the monthly prevalence of the disease between November 1994 and March 1997. Using the information on 24,864 monthly data forms, we describe the very rapid spread of the conjunctivitis epidemic through the eastern house finch population. The epidemic first expanded mainly north, probably carried along by house finches on their return migration, then mainly toward the southeast, and later west. By March 1997, conjunctivitis had been reported from most of the eastern range of the house finch. The prevalence of the disease seemed to fluctuate seasonally with increases in the fall, probably as a result of dispersing juveniles. House finch numbers decreased throughout winter in areas with cold winters and high conjunctivitis prevalence, suggesting significant mortality associated with the disease.

Animals↗
PubMed2006

Factors associated with buying and selling syringes among injection drug users in a setting of one of North America's largest syringe exchange programs.

We performed analyses of syringe buying and syringe selling among Vancouver injection drug users, recruited from May 1996 and followed up between November 2002 and August 2003, in the context of one of North America's largest syringe exchange programs (SEPs). An interviewer-administered questionnaire, approximately 45 minutes in duration, was used to collect information regarding risk factors for HIV infection and sources of sterile syringes. Seventy participants (15%) reported syringe selling and 122 (26%) reported syringe buying. Syringe sellers were more likely to be female, reside in unstable housing, need help injecting, and have visited the SEP at least once weekly. Syringe buyers were more likely to need help injecting, have difficulty finding new syringes, have binged on drugs, and have visited the SEP at least once weekly. Syringe buying most frequently occurred when the SEP was closed.

Acquired Immunodeficiency Syndrome↗