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At least 19 recordsLinked to original sources

PubMed2026

Isolation of rhizobia from Ontario soils that are effective at fixing nitrogen with common bean (Phaseolus vulgaris).

UNLABELLED: Common bean (Phaseolus vulgaris) is an important crop in Canada and globally. Like other legumes, common bean establishes symbiotic interactions with nitrogen-fixing bacteria called rhizobia. However, nitrogen fixation by rhizobia in association with common bean is often suboptimal, constraining its productivity and necessitating the application of nitrogen fertilizer. To support the development of high-performing, locally adapted rhizobial inoculants for Ontario common bean growers, we isolated 216 common bean-nodulating rhizobia from southern Ontario soils using a nodule trapping approach with four common bean cultivars. Whole genome sequencing followed by phylogenomic analyses of all rhizobial isolates revealed substantial diversity, assigning them to 11 Rhizobium species, including two novel species. Nearly all isolates belong to the symbiovar phaseoli, spanning the nodC γ-a, γ-b, and α alleles, with four isolates belonging to the symbiovar gallica. Soil origin had a significant impact on the species-level community composition recovered during the nodule trapping experiments. In contrast, host trapping cultivar had only a minor influence on the recovered Rhizobium population. Greenhouse assays demonstrated that one of the novel Rhizobium species exhibited the highest average symbiotic effectiveness, although high-quality isolates were found across multiple species. Together, these results revealed a diverse and genomically variable Rhizobium community capable of forming effective symbioses with common bean in southern Ontario soils. Importantly, our genome-sequenced Rhizobium collection will serve as a valuable resource for identifying competitive and high-quality strains for the development of inoculants tailored to Ontario common bean production. IMPORTANCE: Common bean is a globally important food crop, yet its productivity is often limited by suboptimal nitrogen fixation, forcing growers to rely on synthetic fertilizers. Consequently, identifying high‑performing, locally adapted inoculant strains is essential for reducing dependence on synthetic nitrogen fertilizers and improving the sustainability of temperate agroecosystems. Our study provides a genome‑sequenced collection of common bean-nodulating Rhizobium from southern Ontario, revealing substantial species and genomic diversity across sampling locations. Greenhouse studies allowed us to identify multiple isolates that consistently fix nitrogen with, and enhance the growth of, common bean plants. Our findings highlight strong biogeographical structuring of the effective and competitive subpopulations of rhizobial communities and demonstrate that Ontario soils already harbor strains with high symbiotic potential. In addition, our Rhizobium collection represents a foundational resource to support future inoculant development and enables future work on the ecology, evolution, and applied optimization of legume-rhizobium symbioses.

Nanopore↗

PubMed2025

Newborn screening for common genetic variants associated with permanent hearing loss: Implementation in Ontario and review of the first 3 years.

PURPOSE: Early hearing detection and intervention (EHDI) programs using audiometric screening techniques alone have a limited ability to detect noncongenital childhood permanent hearing loss (PHL). In 2019, Ontario launched universal newborn screening (NBS) for PHL risk factors, including congenital cytomegalovirus and 22 common variants in GJB2 and SLC26A4. Here, we describe our experience in screening for genetic risk factors. METHODS: Ontario newborns who participated in universal newborn hearing screening (UNHS) were offered risk factor screening using dried blood spots (DBS) collected for conventional newborn screening. The screening was conducted using a custom MassArray assay, and positive results were confirmed by Sanger sequencing or polymerase chain reaction. Diagnostic audiological assessments were performed for all screen-positive infants. RESULTS: Of the 412,424 infants screened, 93 had 2 variants in GJB2 or SLC26A4. Of these, 72 had confirmed PHL, 20 had normal hearing, and 1 declined follow-up. Thirteen infants with PHL (1 in 31,724; 11.8% of screen positives) were not identified through audiometric testing as they passed (3) or missed (10) the screening. Importantly, among infants who ultimately received cochlear implants, the detection of genetic etiology through NBS led to an accelerated time to diagnosis, assessment, and intervention. CONCLUSION: Genetic screening has strengthened UNHS and care for infants with or at risk of PHL in Ontario. This study is a step toward the broader inclusion of genomic testing in NBS.

Humans↗

PubMed1977

Tissue pathology and comparative microanatomy of Onchocerca from a resident of Ontario and other enzootic Onchocerca species from Canada and the U.S.A.

The microanatomy of one male and one female specimen of a zoonotic Onchocera sp in a fibrous nodule excised from the wrist of an Ontario resident, two bovine Onchocerca from Saskatchewan and Manitoba, Canada, and O. cervicalis from the ligamentum nuchae of a horse in Georgia, U.S.A., were compared. In dimensions and cuticular morphology, the three Canadian specimens of Onchocera shared certain features and closely resembled both O. cervicalis and O. gutturosa. The number of cuticular striae in some species of Onchocerca, particularly in male worms, is briefly discussed and its taxonomic value questioned. The Canadian patient visited Radlett, Hertfordshire, England, and then her summer cottage in the Muskoka region, Ontario, prior to the appearance of her symptoms, so that it is uncertain where she acquired the infection. Zoonotic onchocerciasis has yet to be described from Ontario. All nine cases of bovine onchocerciasis (the two described here and seven others) have occurred in Manitoba and Saskatchewan.

Adult↗

PubMed1979

Variations in surgery in Ontario.

In 1974 there was five-to eight-fold variation in the frequency with which tonsillectomy, colectomy, hysterectomy, cholecystectomy and appendectomy were performed in Ontario's 49 counties. All five procedures were resource sensitive; over 50 per cent of the variation in rates was explained by numbers of acute care treatment beds and physicians. Generally, counties with high or low rates for any one procedure had corresponding rates for the other four. The highest rates were found in less populous rural eastern Ontario counties, while university teaching centers ranked among the lowest for all five operations although they had the highest ratios of beds, general practitioners and surgeons. Linkages between university medical centers and community hospitals, widespread dissemination of surgical rate data, surgical audit and review of surgical indications and practices in university centers and community hospitals are proposed to aid in rationalizing surgical practices in Ontario.

Analysis of Variance↗

PubMed1977

Patterns of practice in internal medicine in Ontario.

To determine the feasibility of wholly referral practice in internal medicine within a prepaid health service, the practice profiles of 694 internists in metropolitan, nonmetropolitan urban, and rural areas of Ontario were delineated by analysis of data from questionnaires and health-insurance billing. The questionnaire showed that two thirds of internists, chiefly younger practitioners, confined themselves to a referral consultant practice; the other one third included primary care. Subspecialists practised predominantly in metropolitan areas; most general internists in such areas provided primary care, whereas most general internists elsewhere had an entirely referral practice. This pattern of practice is greatly different from that in the United States but probably similar to that in other provinces in Canada. Extension of wholly referral practice to all internists in Ontario appears feasible, provided the numbers entering residency training are controlled. The present Ontario curricula for internal medicine and its subspecialties appear suitable for such a pattern of practice.

Humans↗

PubMed1975

Studies of mortality and morbidity data. II. Mortality from all causes in Ontario Counties during 1964-1968.

Age-adjusted mortality rates, for all causes of death, are tabulated for all ages by sex for the 55 Ontario counties and districts. The rates are based on all deaths of Ontario residents during 1964-1968 and 1966 census populations. The consistent trends in rates, both for the two sexes and for various 10- and 20-year age groups, indicate that there is a region of about eight adjoining counties, across the center of the province, which has abnormally high mortality, and two regions to the east and west of York, each consisting of three adjoining counties which have abnormally low mortality. The relevance of these findings to aging studies is indicated, and possible further investigations of them are discussed.

Adult↗

PubMed1978

California encephalitis virus activity in mosquitoes and horses in southern Ontario, 1975.

A study was undertaken in 1975 to determine California encephalitis virus activity in southern Ontario. Three thousand and sixty-one mosquitoes, primarily Aedes species, were divided into 104 pools and inoculated into suckling mice. Isolates of snowshoe hare virus were obtained from one pool each of Aedes fitchii and A. triseriatus mosquitoes collected in the Guelph area. Serological testing of horse sera revealed extensive virus activity in southern Ontario and indicated that horses may serve as excellent monitors for California encephalitis virus.

Aedes↗

PubMed1975

Paragonimus kellicotti infection in wild carnivores in southwestern Ontario: I. Prevalence and gross pathologic features.

Paragonimus kellicotti Ward, 1908 was recovered from 16 of 105 mink (Mustela vison), 14 of 244 striped skunks (Mephitis mephitis), 10 of 446 red foxes (Vulpes vulpes), 1 of 31 coyotes (Canis latrans), 0 of 326 raccoons (Procyon lotor) and 0 of 8 weasels (Mustela spp.) collected from southwestern Ontario. The majority of carnivores harboring P. kellicotti was collected from two counties (Huron and Bruce) bordering the east shore of Lake Huron where 6.0% of the animals (excluding raccoons) were infected . There were extensive adhesions between the lungs and parietal pleura and dorsal mediastinal pleura in 25 of 301 raccoons collected from these two counties. This lesion was thought to be associated with a reaction to migrating P. kellicotti. This is the first time P.kellicotti has been reported in the striped skunk and red fox from Ontario and apparently the first record of this parasite in the coyote.

Animals↗

PubMed1976

Insecticide residues on stream sediments in Ontario, Canada.

Insecticide residues on suspended and bottom sediments of streams of Ontario, Canada, have been studied in a tobacco-growing and a vegetable muck area. The proportion of TDE to DDT was less than 1 in water and greater than 1 in bottom sediments. The ratio of TDE to DDT in bottom material increased linearly from the contamination point at stream source to the mouth of Big Creek in Norfolk County, Ontario. Bed load samples contained three to six times greater concentrations of insecticides than bottom material. Adsorption of insecticides on suspended sediment decreased in order DDT greater than TDE greater than dieldrin greater than diazinon, which is consistent with the water solubility of these compounds.

Chromatography, Gas↗

PubMed1975

On paying the fiddler to change the tune: further evidence from Ontario regarding the impace of universal health insurance on the organization and patterns of medical practice.

This paper compares the findings from a 1973 community household interview survey conducted in Sault Ste. Marie, Ontario, with the findings from a similar study conducted in 1968 in the same city by a research team from the World Health Organization. Sault Ste. Marie is the site of the first Canadian consumer-sponsored prepaid group practice. Opposition by the private, solo practice sector of this community to this new modality of medical practice was considerable. Since 1969, with the introduction of universal health insurance in Ontario, the cost and benefit differences between solo and group practice medical care have been eliminated. By comparing the findings from the 1973 study with similar data from the 1968 WHO survey, observations can be made about the impact of universal health insurance on the organization and patterns of medical practice. Implications for the United States are important in view of the recent passage of the Health Maintenance Organization Act of 1973 and the expected enactment of some form of national health insurance.

Consumer Behavior↗

PubMed1977

Antimicrobial susceptibility of Salmonella isolates from the broiler chicken industry in Ontario.

Antibacterial drug resistance among 219 salmonella isolates recovered during 1974 from poultry and poultry environments at the various production stages of broiler chickens in three integrated Ontario companies are recorded. All isolates were susceptible to ampicillin, trimethroprim-sulfamethoxazole complex, furazolidone, cephaloridine and amoxicillin. A relative increase in resistance to tetracycline and streptomycin with an accompanying decrease in resistance to triple sulfa compound was recorded when compared to a previous investigation of avian salmonella isolates in Ontario. The percentage and patterns of antimicrobial resistance were comparable at the various stages of production. Resistance to tetracycline and streptomycin was the most common pattern found among both Salmonella typhimurium and other serotypes. A notably high prevalence of resistance was found among Salmonella enteritidis isolates including some isolates with R factors for chloramphenicol resistance. This latter finding is of particular concern because of the high prevalence of this serotype in poultry and in human salmonellosis.

Animals↗

PubMed1977

St. Louis encephalitis in southern Ontario: laboratory studies for arboviruses.

The first reported outbreak of St. Louis encephalitis in Canada occurred in the summer of 1975 in southern Ontario -- in the Windsor-Sarnia-Chatham area, the Niagara region and the city of Toronto. Hemmagglutination inhibition and complement fixation testing of serum samples collected during the outbreak confirmed that St. Louis encephalitis virus was the etiologic agent. Furthermore, this virus was isolated from brain tissue of a patient who died. This outbreak was probably an extension of the outbreak that occurred in the United States that summer. It was the first outbreak of arbovirus encephalitis in the province of Ontario.

Antibodies, Viral↗

PubMed1977

Surgery and anesthesia in Ontario.

Operative and case-fatality rates in Ontario for eight elective (discretionary) and seven nonelective (nondiscretionary) operations and the proportions of these operations and their anesthetic procedures performed by general practitioners were calculated. Cholecystectomy increased in frequency 32% from 1968 through 1973, tonsillectomy and adenoidectomy decreased 37%, and hysterectomy increased 41%. Except for colectomy the rates for nonelective operations changed only slightly over the 6 years. Case-fatality rates (hospital deaths per 10000 operations) for the discretionary operations in 1973 were as follows: extraction of lens, 23.1; tonsillectomy and adenoidectomy, 0.4 (2 deaths among 52938 operations); varicose vein stripping, 6.1; nonrecurrent inguinal herniorrhaphy, 21.9; cholecystectomy, 61.0; hemorrhoidectomy, 9.8; prostatectomy, 115.9; and hysterectomy, 9.6. In 1973 general practitioners did 32% of tonsillectomies and adenoidectomies (61% in 1971), 10 to 20% of inguinal herniorrhaphies, hemorrhoidectomies and appendectomies and 6% or less of the other operations. However, they performed 35% or more of the anesthetic procedures for these four operations as well as for varicose vein stripping, cholecystectomy and hysterectomy. Rates of general-practice surgery and anesthesia in an urban centre in Ontario were substantially less than those for the province as a whole.

Adolescent↗

PubMed1979

Fire deaths and drinking: data from the Ontario fire reporting system.

Data on recorded alcohol impairment of 264 victims of fatal fires in Ontario in 1976 are analyzed. Male victims were twice as likely to be impaired as females, and impairment was more common among those under 50 years of age. Alcohol impairment was most often noted in victims of fires at night and on weekends. Overall, 31% of adult victims were reported as alcohol impaired. The Ontario data suggests alcohol involvement in victims was not associated with smoking as a cause of the fire.

Alcohol Drinking↗

PubMed1975

Residue of organochlorine compounds and mercury in birds' eggs from the Niagara Peninsula, Ontario.

Eggs (307) were collected in 1971 from twenty species of birds with a variety of feeding habits from the Niagara Peninsula. This area of ontario is intensively developed for agriculture and heavy industry and has a large urban population. Representative species were obtained from both the terrestrial and aquatic food chains. Eggs were analyzed for organochlorine insecticides, polychlorinated biphenyls, and total mercury. Eggs from carnivorous species at the top of the aquatic food chain had the highest mean residues of signa DDT(7.6to 22.4 pm), PCB (3.5 to 74.0 ppm) and total mercury (0.64 to 0.83 ppm). Eggs from some terrestrial carnivores (red-tailed hawk and great horned owl) also had relatively high residues (2.5 to 3.9 ppm of sigmaDDT, 0.2 to 1.0 ppm of PCB, 0.06 to 0.09 ppm of mercury, however levels were much lower than those found in eggs from aquatic-feeding carnivores. Eggs from one red-shouldered hawk had residues comparable to the aquatic feeding carnivores. Eggs from herbivorous and insectivorous birds of both aquatic and terrestrial environments contained much lower residues. PCB residues were slightly lower in eggs among the terrestrial feeding species (0.05 to 2.0 ppm) than among the aquatic feeders (0.14 to4.0 ppm) and tended to be lower in eggs from terrestrial species collected in rural than incity environs. Levels of sigmaDDT were similar in both groups with eggs from terrestrial feeders containing mean resisues between 0.15 and 2.64 ppm and those from aquatic feeders between 0.33 and 2.79 ppm.

Animals↗

PubMed1976

Insecticide and nutrient transport in water, related to agricultural land use of a stream basin in Ontario, Canada.

Transport by stream water of insecticides and nutrients in Big Creek, Norfolk County, Ontario, Canada, was examined by combining concentrations of substrates with flow data. Big Creek has its headwaters in dairy cattle country, its central basin area is mainly devoted to tobacco growing, and its lower reaches contain mixed farming, corn and vegetables, etc., before it flows into Lake Erie. Three sampling sites were chosen to represent these 3 different land uses. Generally concentrations of substrates in the water were quite uniform at the 3 sites resulting in transport of quantities in proportion to stream flow. Certain anomalies occurred and are discussed. The 2 chief insecticides found were DDT and dieldrin. Analyses for potassium, calcium and magnesium indicated that these nutrient losses into the stream were area-rather than usage-dependent. Midseason variations in loss of nitrogen and phosphorus may be the result of agricultural practices in the three areas represented in this study. The largest quantities of all nutrients lost occurred early in the season before crops were established.

Agriculture↗

PubMed2026

A retrospective population-based cohort study to assess outcomes, time to complications and cost of follow-up care following pediatric pyeloplasty in Ontario, Canada (2002-2016).

PURPOSE: Pediatric dismembered pyeloplasty (PP) is the gold standard surgery for uretero-pelvic junction obstruction (UPJO) in children. However, there is no consensus regarding the duration and methods of providing follow-up care after PP. This study aims to assess the rate of redo-interventions following PP and to define the ideal follow-up care following PP. MATERIALS AND METHODS: This is a retrospective population-based cohort study including all PP patients in Ontario between April 2002 and March 2016 using routinely collected data, with a minimum 5-year follow-up. Baseline variables included demographics, surgical approach, laterality and surgeon experience. The primary outcome was time to secondary surgical intervention, including redo PP. Secondary outcomes included costs of follow-up care and rates of early ER visits. Regression analyses were preformed to predict need for secondary intervention 2-years post PP, including independent variables: age, sex, surgical approach and early complication. RESULTS: The study included 1049 patients with a median age of 2 (IQR 0-7) years. Of the 13.6% of patients who had at least one secondary intervention following PP (including 3.8% who underwent a redo PP), 90.2% occurred within 3-years of PP. The median cost/patient of follow up care was $1472 CAD (IQR $292-$31,133). Regression analysis did not reveal any predictors of delayed secondary intervention. CONCLUSIONS: This study demonstrates that over 86% of PP are completed successfully, with a 3.8% rate of redo-PP. The majority of secondary interventions for post-PP complications occur within 3 years post-PP. Variability in duration and cost of follow-up care post- PP should be addressed to minimize costs, and a minimum 3-years follow-up after PP is recommended.

Humans↗

PubMed1977

The prevalence and epidemiology of toxoplasmosis in Ontario.

The results of testing 7060 human serum specimens obtained in the Province of Ontario, Canada, were analysed for the presence of antibodies to Toxoplasma gondii. Of these samples 38% were serologically positive at a titre of 1/16 or greater. The age-specific rates climbed from 2.7% in infants between 6 months and 1 year of age, to about 50% in individuals aged 25 years or over. Variations in prevalence were noted between different areas within the province and evidence is put forward to show that an inverse relation exists between urban size and toxoplasma prevalence. Seasonal and annual variations were not shown to be significant. On the basis of a very small sample of specimens, cat ownership not appear to cause a significant increase in the risk of acquiring this infection.

Adolescent↗