Use of molecular subtyping to document long-term persistence of Corynebacterium diphtheriae in South Dakota.
(1/124)
Enhanced surveillance of patients with upper respiratory symptoms in a Northern Plains community revealed that approximately 4% of them were infected by toxigenic Corynebacterium diphtheriae of both mitis and gravis biotypes, showing that the organism is still circulating in the United States. Toxigenic C. diphtheriae was isolated from five members of four households. Four molecular subtyping methods-ribotyping, multilocus enzyme electrophoresis (MEE), random amplified polymorphic DNA (RAPD), and single-strand conformation polymorphism-were used to molecularly characterize these strains and compare them to 17 archival South Dakota strains dating back to 1973 through 1983 and to 5 isolates collected from residents of diverse regions of the United States. Ribotyping and RAPD clearly demonstrated the household transmission of isolates and provided precise information on the circulation of several distinct strains within three households. By MEE, most recent and archival South Dakota strains were identified as closely related and clustered within the newly identified ET (electrophoretic type) 215 complex. Furthermore, three recent South Dakota isolates and eight archival South Dakota isolates were indistinguishable by both ribotyping and RAPD. All of these molecular methods showed that recent South Dakota isolates and archival South Dakota isolates were more closely related to each other than to the C. diphtheriae strains isolated in other parts of the United States or worldwide. The data also supported the improbability of importation of C. diphtheriae into this area and rather strongly suggest the long-term persistence of the organism in this region. (+info)
Rising tide of cardiovascular disease in American Indians. The Strong Heart Study.
(2/124)
BACKGROUND: Although cardiovascular disease (CVD) used to be rare among American Indians, Indian Health Service data suggest that CVD mortality rates vary greatly among American Indian communities and appear to be increasing. The Strong Heart Study was initiated to investigate CVD and its risk factors in American Indians in 13 communities in Arizona, Oklahoma, and South/North Dakota. METHODS AND RESULTS: A total of 4549 participants (1846 men and 2703 women 45 to 74 years old) who were seen at the baseline (1989 to 1991) examination were subjected to surveillance (average 4.2 years, 1991 to 1995), and 88% of those remaining alive underwent a second examination (1993 to 1995). The medical records of all participants were exhaustively reviewed to ascertain nonfatal cardiovascular events that occurred since the baseline examination or to definitively determine cause of death. CVD morbidity and mortality rates were higher in men than in women and were similar in the 3 geographic areas. Coronary heart disease (CHD) incidence rates among American Indian men and women were almost 2-fold higher than those in the Atherosclerosis Risk in Communities Study. Significant independent predictors of CVD in women were diabetes, age, obesity (inverse), LDL cholesterol, albuminuria, triglycerides, and hypertension. In men, diabetes, age, LDL cholesterol, albuminuria, and hypertension were independent predictors of CVD. CONCLUSIONS: At present, CHD rates in American Indians exceed rates in other US populations and may more often be fatal. Unlike other ethnic groups, American Indians appear to have an increasing incidence of CHD, possibly related to the high prevalence of diabetes. In the general US population, the rising prevalence of obesity and diabetes may reverse the decline in CVD death rates. Therefore, aggressive programs to control diabetes and its risk factors are needed. (+info)
Dual use of VA and non-VA primary care.
(3/124)
OBJECTIVE: To determine how frequently veterans use non-Department of Veterans Affairs (VA) sources of care in addition to primary care provided by the VA and to assess the association of this pattern of "dual use" to patient characteristics and satisfaction with VA care. DESIGN: Cross-sectional telephone survey of randomly selected patients from four VA medical centers. PARTICIPANTS: Of 1,240 eligible veterans, 830 (67%) participated in the survey. MEASUREMENTS AND MAIN RESULTS: Survey data were used to assess whether a veteran reported receiving primary care from both VA and non-VA sources of care, as well as the proportion of all primary care visits made to non-VA providers. Of 577 veterans who reported VA primary care visits, 159 (28%) also reported non-VA primary care visits. Among these dual users the mean proportion of non-VA primary care visits was 0.50. Multivariate analysis revealed that the odds of dual use were reduced for those without insurance (odds ratio [OR] 0.34; 95% confidence interval [CI] 0.18, 0.66) and with less education (OR 0.60; 95% CI 0.38, 0.92), while increased for those not satisfied with VA care (OR 2.40; 95% CI 1.40, 4.13). Among primary care dual users, the proportion of primary care visits made to non-VA providers was decreased for patients with heart disease ( p <.05) and patients with alcohol or drug dependence ( p <.05). CONCLUSIONS: Primary care dual use was common among these veterans. Those with more education, those with any type of insurance, and those not satisfied with VA care were more likely to be dual users. Non-VA care accounted for approximately half of dual users' total primary care visits. (+info)
Developmental selection within the angiosperm style: using gamete DNA to visualize interspecific pollen competition.
(4/124)
Among flowering plants, females often have little control over the genetic relatedness of pollen deposited on stigmas. Thus, postpollination processes are of primary importance for mate discrimination. The ability to screen and select among male gametes during pollen tube growth within the female tissues of the stigma, style, and ovary is critical to the process of mate choice and reproductive isolation. However, direct evidence of the mechanistic/developmental processes associated with mate choice in flowering plants is sparse. We studied the contribution of postpollination, prefertilization processes to reproductive isolation in two wind-pollinated species of birch (Betula) that commonly hybridize in nature. We exploited the 3-fold difference in ploidy level between these two species to determine the paternity of individual pollen tubes growing within female reproductive tissues. We then tracked their developmental fate in conspecific, heterospecific, and mixed-species crosses. This design allowed a direct comparison of developmental processes responsible for reproductive isolation in both single-species and mixed-species pollinations. Our results have important implications for the population genetic outcome of hybridization dynamics in natural populations. Paternity analysis of progeny from mixed-species pollinations revealed that conspecific pollen tubes sired more than 98% of seedlings. Biased siring success was not the result of differential embryo abortion. We detected strong, early postpollination barriers such as pollen tube incompatibility, slower pollen tube growth, and delayed generative cell mitosis. Conspecific fertilization precedence was mediated by favorable or unfavorable male-female interactions, but there was no evidence for antagonistic male-male interactions. (+info)
Use of the Semmes-Weinstein monofilament in the strong heart study. Risk factors for clinical neuropathy.
(5/124)
OBJECTIVE: We used the Semmes-Weinstein 5.07 monofilament to assess the prevalence of foot insensitivity and its relationship to potential risk factors. RESEARCH DESIGN AND METHODS: There were 3,638 American Indian participants from Arizona, North and South Dakota, and Oklahoma who attended a study clinic on two occasions: baseline and follow-up, 4 years later. Oral glucose tolerance tests were performed at the visits for those who had not previously been diagnosed as having diabetes. A total of 2,051 participants were diagnosed with diabetes before the study or at the subsequent study visits. At the follow-up visit, participants were tested for their ability to sense the 5.07 (10 g) monofilament at 10 sites of the foot. The prevalence of foot insensitivity was ascertained, and its relation to characteristics of participants was assessed in both univariate and logistic regression analyses. RESULTS: Diabetic participants had a much higher prevalence of foot insensitivity (defined as greater than or equal to five incorrect responses) than nondiabetic participants (14 vs. 5%, respectively). However, marked foot insensitivity was uncommon within the first few years of diagnosis of diabetes. Among the diabetic participants, those diagnosed before study entry had the highest prevalence of foot insensitivity. The prevalence of foot insensitivity was highest in the Arizona Indians (22 vs. 9% in the Dakotas and 8% in Oklahoma). In a logistic regression analysis, foot insensitivity was significantly and independently related to center (Arizona versus others), age, duration of diabetes, and height. CONCLUSIONS: Marked foot insensitivity is prevalent in the diabetic American Indian population, especially in Indians in Arizona; however, this insensitivity is apparently uncommon for several years after the diagnosis of diabetes. The data show that Indians with diabetes are particularly vulnerable to the risk of foot ulceration and that the diagnostic screening of diabetes may lead to better prevention of sensory neuropathy and subsequent foot ulceration. (+info)
Glycemic control in diabetic American Indians. Longitudinal data from the Strong Heart Study.
(6/124)
OBJECTIVE: To describe glycemic control and identify correlates of elevated HbA1c levels in diabetic American Indians participating in the Strong Heart Study, which is a longitudinal study of cardiovascular disease in American Indians in Arizona, Oklahoma, South Dakota, and North Dakota. RESEARCH DESIGN AND METHODS: This analysis is based on data from the baseline (1989-1992) and first follow-up (1994-1995) examinations of the Strong Heart Study. The 1,581 diabetic participants included in this analysis were aged 45-74 years at baseline, were diagnosed with diabetes before and at baseline, and had their HbA1c levels measured at follow-up. HbA1c was used as the index of glycemic control. Characteristics that may affect glycemic control were evaluated for cross-sectional and longitudinal relationships by analysis of covariance and multiple regression. RESULTS: There was no significant difference between median HbA1c at baseline (8.4%) and at follow-up (8.5%). Sex, age (inversely), and insulin and oral hypoglycemic agent therapy were significantly related to HbA1c levels in both the cross-sectional and longitudinal analyses. Current smoking, prior use of alcohol, and duration of diabetes were significant only for the cross-sectional data. Baseline HbA1c significantly and positively predicted HbA1c levels at follow-up. Comparison of HbA1c by therapy type shows that insulin therapy produced a significant decrease in HbA1c between the baseline and follow-up examinations. CONCLUSIONS: Glycemic control was poor among diabetic American Indians participating in the Strong Heart Study. Women, patients taking insulin or oral hypoglycemic agents, and younger individuals had the worst control of all the participants. Baseline HbA1c, and weight loss predicted worsening of control, whereas insulin therapy predicted improvement in control. Additional therapies and/or approaches are needed to improve glycemic control in this population. (+info)
Prevalence of Escherichia coli O157:H7 in range beef calves at weaning.
(7/124)
This study was designed to determine the prevalence of Escherichia coli O157:H7 infection of beef calves at weaning, prior to arrival at the feedlot or mixing with cattle from other sources. Fifteen range cow-calf herds, which weaned calves in October and November, were sampled in Kansas, Missouri, Montana, Nebraska and South Dakota. Faecal culture for E. coli O157:H7 was performed and anti-O157 serum antibody titres were determined by blocking ELISA. Thirteen of the 15 herds (87%) were found to have at least one positive isolation of E. coli O157:H7 in faecal samples. Within positive herds, prevalence ranged from 1.7-20.0%, with an average of 7.4+/-6.2% S.D. of individual animals shedding E. coli O157:H7 in faeces. All herds had high prevalence of anti-O157 antibodies, ranging 63-100% of individuals within herds seropositive. This study indicates that E. coli O157:H7 infection before weaning, prior to entry into feedlots, is widespread. Furthermore, serologic evidence suggests that most calves (83%) and all herds (100%) have been exposed to E. coli O157. (+info)
Estimation of variance components of quantitative traits in inbred populations.
(8/124)
Use of variance-component estimation for mapping of quantitative-trait loci in humans is a subject of great current interest. When only trait values, not genotypic information, are considered, variance-component estimation can also be used to estimate heritability of a quantitative trait. Inbred pedigrees present special challenges for variance-component estimation. First, there are more variance components to be estimated in the inbred case, even for a relatively simple model including additive, dominance, and environmental effects. Second, more identity coefficients need to be calculated from an inbred pedigree in order to perform the estimation, and these are computationally more difficult to obtain in the inbred than in the outbred case. As a result, inbreeding effects have generally been ignored in practice. We describe here the calculation of identity coefficients and estimation of variance components of quantitative traits in large inbred pedigrees, using the example of HDL in the Hutterites. We use a multivariate normal model for the genetic effects, extending the central-limit theorem of Lange to allow for both inbreeding and dominance under the assumptions of our variance-component model. We use simulated examples to give an indication of under what conditions one has the power to detect the additional variance components and to examine their impact on variance-component estimation. We discuss the implications for mapping and heritability estimation by use of variance components in inbred populations. (+info)