Evaluation of Winter Ticks (Dermacentor albipictus) Collected from North American Elk (Cervus canadensis) in an Area of Chronic Wasting Disease Endemicity for Evidence of PrPCWD Amplification Using Real-Time Quaking-Induced Conversion Assay.

Chronic wasting disease (CWD) is a progressive and fatal spongiform encephalopathy of deer and elk species, caused by a misfolded variant of the normal prion protein. Horizontal transmission of the misfolded CWD prion between animals is thought to occur through shedding in saliva and other forms of excreta. The role of blood in CWD transmission is less clear, though infectivity has been demonstrated in various blood fractions. Blood-feeding insects, including ticks, are known vectors for a range of bacterial and viral infections in animals and humans, though to date, there has been no evidence for their involvement in prion disease transmission. In the present study, we evaluated winter ticks (Dermacentor albipictus) collected from 136 North American elk (Cervus canadensis) in an area where CWD is endemic for evidence of CWD prion amplification using the real-time quaking-induced conversion assay (RT-QuIC). Although 30 elk were found to be CWD positive (22%) postmortem, amplifiable prions were found in just a single tick collected from an elk in advanced stages of CWD infection, with some evidence for prions in ticks collected from elk in mid-stage infection. These findings suggest that further investigation of ticks as reservoirs for prion disease may be warranted. IMPORTANCE This study reports the first finding of detectable levels of prions linked to chronic wasting disease in a tick collected from a clinically infected elk. Using the real-time quaking-induced conversion assay (RT-QuIC), "suspect" samples were also identified; these suspect ticks were more likely to have been collected from CWD-positive elk, though suspect amplification was also observed in ticks collected from CWD-negative elk. Observed levels were at the lower end of our detection limits, though our findings suggest that additional research evaluating ticks collected from animals in late-stage disease may be warranted to further evaluate the role of ticks as potential vectors of chronic wasting disease.

Management of chronic wasting disease in ranched elk: conclusions from a longitudinal three-year study.

Chronic wasting disease is a fatal, horizontally transmissible prion disease of cervid species that has been reported in free-ranging and farmed animals in North America, Scandinavia, and Korea. Like other prion diseases, CWD susceptibility is partly dependent on the sequence of the prion protein encoded by the host's PRNP gene; it is unknown if variations in PRNP have any meaningful effects on other aspects of health. Conventional diagnosis of CWD relies on ELISA or IHC testing of samples collected post-mortem, with recent efforts focused on antemortem testing approaches. We report on the conclusions of a study evaluating the role of antemortem testing of rectal biopsies collected from over 570 elk in a privately managed herd, and the results of both an amplification assay (RT-QuIC) and conventional IHC among animals with a several PRNP genotypes. Links between PRNP genotype and potential markers of evolutionary fitness, including pregnancy rates, body condition, and annual return rates were also examined. We found that the RT-QuIC assay identified significantly more CWD positive animals than conventional IHC across the course of the study, and was less affected by factors known to influence IHC sensitivity - including follicle count and PRNP genotype. We also found that several evolutionary markers of fitness were not adversely correlated with specific PRNP genotypes. While the financial burden of the disease in this herd was ultimately unsustainable for the herd owners, our scientific findings and the hurdles encountered will assist future CWD management strategies in both wild and farmed elk and deer.

Cross-validation of the RT-QuIC assay for the antemortem detection of chronic wasting disease in elk.

Chronic wasting disease is a progressively fatal, horizontally transmissible prion disease affecting several members of the cervid species. Conventional diagnosis relies on ELISA or IHC evaluation using tissues collected post-mortem; however, recent research has focused on newly developed amplification techniques using samples collected antemortem. The present study sought to cross-validate the real-time quaking-induced conversion assay (RT-QuIC) evaluation of rectal biopsies collected from an elk herd with endemic CWD, assessing both binary positive/negative test results as well as relative rates of amplification between laboratories. We found that results were correlative in both categories across all laboratories performing RT-QuIC, as well as to conventional IHC performed at a national reference laboratory. A significantly higher number of positive samples were identified using RT-QuIC, with results seemingly unhindered by low follicle counts. These findings support the continued development and implementation of amplification assays in the diagnosis of prion diseases of veterinary importance, targeting not just antemortem sampling strategies, but post-mortem testing approaches as well.

A cross-sectional study of IGF-I determinants in women.

Evidence is accumulating that elevated circulating insulin-like growth factor I (IGF-I) is related to increased cancer risk. The identification of hormonal, reproductive and lifestyle characteristics influencing its synthesis and bioavailability is of particular interest. Data from 400 women, who served as controls in two case-control studies nested within the same prospective cohort study, were combined. IGF-I, IGF-binding proteins 1, 2 and 3 (IGFBP-1, -2, -3) and insulin were measured in serum samples from all subjects and cotinine in 186 samples. Age appears to be the most important determinant of total IGF-I levels in women. Anthropometric measures, such as body mass index (BMI) or waist-to-hip ratio (WHR) do not seem to influence total IGF-I concentrations in peripheral blood, but may modulate IGF-I bioavailability through insulin-dependent changes in IGFBP-1 and -2 concentrations. Age at menarche, phase of the menstrual cycle at blood draw, parity, menopause, past oral contraceptive or hormone replacement therapy use, and tobacco smoking do not appear to exert an independent effect on IGF-I and its binding proteins. There was some suggestion that regular physical activity may increase total IGF-I and that women with positive family history of breast cancer might have higher IGF-I levels than those without such diagnosis in their relatives.

A prospective study of insulin-like growth factor-I, IGF-binding proteins-1, -2 and -3 and lung cancer risk in women.

Insulin-like growth factor-I (IGF-I) has mitogenic and anti-apoptotic properties and has been implicated in the development of breast, colorectum, prostate and lung cancer. IGF binding proteins (IGFBPs) are not only carrier proteins for IGFs but also hold a central position in IGF ligand-receptor interactions through influences on the bioavailability and distribution of IGFs in the extracellular environment. A case-control study nested within the New York University Women's Health Study Cohort included 93 women diagnosed with lung cancer at least 6 months after recruitment into the study. Two controls (n = 186) were matched to each case on age, date of blood sampling, menopausal status, day of menstrual cycle and questionnaire data of smoking status at the time of blood donation. Serum IGF-I, IGFBP-1, -2 and -3, insulin and cotinine were measured. Mean serum levels of IGF-I, IGFBP-1, -2 and -3 were not significantly different between the case and control groups. Univariate logistic regression analyses showed no association of lung cancer risk with serum levels of IGF-I or any of the IGFBPs. These results remained virtually the same in multivariate analyses, including adjustment for cotinine, time since last meal, BMI, IGF-I or IGFBP-3, respectively. Exclusion of cases diagnosed within 3 years of recruitment in the cohort, or restriction of the analyses to adenocarcinomas only, did not alter these results. Our study does not offer evidence in support of an association between prediagnostic serum levels of IGF-I or IGFBP-1, -2 and -3 and lung cancer risk in women.

Acute respiratory response to prolonged, moderate levels of sidestream tobacco smoke.

Environmental tobacco smoke (ETS) is a significant component of indoor air pollution yet the acute upper respiratory response has not been well studied. The goal of this study was to determine the response of healthy subjects to moderate levels of sidestream tobacco smoke (SS). Twenty-three subjects were challenged on 2 separate days to clean air or SS (2 h, 15 ppm carbon monoxide, at rest). Subjects completed symptom questionnaires, posterior rhinomanometry, and body plethysmography. Average total and differential cell counts and albumin concentration were determined on nasal lavage samples. The urinary cotinine: creatinine ratio was used as a biomarker of exposure. Following SS exposure, irritant and rhinitis symptoms increased, nasal resistance rose from 4.9+/-0.4 to 6.3+/-0.6 cm H2O/L/s and specific airway conductance decreased from 0.14+/-0.01 to 0.13+/-0.01 cm H2O(-1) s(-1). Total cell counts, neutrophils, and albumin were unchanged. An increased nasal congestive response did not correlate with an increased cotinine: creatinine ratio. A history of ETS rhinitis did not predict an increased group response to smoke, but individuals with the largest physiologic and inflammatory response were historically ETS sensitive. In summary, healthy normal subjects demonstrate nasal congestion with exposure to moderate levels of SS without evidence of increased nasal vascular permeability.

Factors modifying exposure to environmental tobacco smoke in children (Athens, Greece).

The aim of the study was to investigate individual, family, and environmental factors which may modify exposure of children to environmental tobacco smoke (ETS). A total of 2,108 children of both genders, aged up to 14 years old, were enrolled in the study. Parents of the children provided information concerning several factors that may affect exposure to ETS. Cotinine-to-creatinine ratios in spot urine samples were measured for each child. These values were logtransformed and regressed on a series of exposure variables. Among children, 73 percent were exposed to ETS generated by at least one smoker in the household. Exposure to ETS was affected by the following factors: cigarettes smoked by parents while the child was at home (increase by 37 percent per 10 cigarettes daily, 95 percent confidence interval [CI] = 32-43 percent); precautions taken by parents (no cf yes, increase by 38 percent, CI = 24-54 percent); child's age (decrease by nine percent per year, CI = -11-8 percent); gender (male lower than female by 13 percent, CI = -21-3 percent); day of the week (Monday cf Tuesday-through-Sunday, increase by 28 percent, CI = 14-44 percent); floor surface area (decrease by nine percent per 20 m2, CI = -14-5 percent); heating (central cf non-central decrease by 14 percent, CI = -25-2 percent); maternal education (decrease by nine percent per five years, CI = -18-0 percent); paternal education (decrease by seven percent per five years, CI = -15-2 percent). It is concluded that several household-related factors affect exposure to ETS and that this exposure can be reduced by about one-third by simple precautions taken by smoking parents.

Do the nonsmoking daughters of smokers tend to marry smokers? Implications for epidemiological research on environmental tobacco smoke: the IARC collaborative study.

The IARC collaborative study on exposure to environmental tobacco smoke (ETS) involved collecting interview data and biochemical indicators of exposure from 1369 nonsmoking women in 13 centers in 10 countries. Information on childhood and adulthood exposure to other people's smoke and duration of this exposure from both parents and spouse was gathered at the interview. Of the 900 women whose husbands smoked (current or exsmokers), 71.3% had one or both parents who smoked (predominantly the father), whereas among the 277 women married to never-smokers, only 60.3% had at least one parent who smoked. The odds ratio for the daughter of a smoker to marry a smoker was, therefore, 1.64 (95% confidence interval = 1.24-2.17; P > 0.001), and there was an exposure-response relation between the number of years of childhood exposure to ETS from the parents and the likelihood of being married to a smoker. These results show that nonsmoking women married to smokers are more likely to have been exposed to tobacco pollution during their whole life. Because the duration of exposure is known to be important in the genesis of lung cancer, some of the excess risk of lung cancer in nonsmoking women married to smokers may be due exposure to ETS from parents during childhood.

Effects of alcohol and prescription and over-the-counter drug use on liver enzyme profiles.

Liver function tests are commonly ordered during routine checkups or in an effort to identify the cause of underlying disease. Elevated liver enzymes usually indicate a disease or an insult to the liver, the main causes of which can be hepatitis (caused by virus infection or chemical exposures) or cirrhosis of the liver due to alcohol abuse. Results from the Metropolitan Life Insurance Testing Laboratory confirm national data showing a slow rise in the percentage of "free-living" persons with elevated liver enzymes. The percentage of "abnormal" results increased despite unchanged analytic methods or quality control measures during the data gathering period. In addition, the proportions of abnormal enzyme levels have increased while U.S. per capita alcohol consumption has decreased and sales of over-the-counter medications that elevate liver enzymes have increased. Thus, it is increasingly more difficult to determine the true cause of elevated liver enzymes. As more Americans self-medicate and as more prescription drugs become available over-the-counter, which can have subtle or overt effects on liver enzyme secretion, the causes for abnormal enzyme levels will remain difficult to interpret. Continued monitoring of liver enzyme levels and the prevalence of drug and alcohol use are necessary to determine if the noted rise in abnormal levels is associated with increased morbidity or adverse outcome.

Validity of urinary biomarkers of exposure to tobacco smoke following prolonged storage.

BACKGROUND: The utility of using biomarkers of smoking in epidemiological studies depends not only on the validity and precision of the laboratory procedure but often on the long-term stability of the analytes of interest in stored biological samples. METHODS: We retrieved urine samples collected in 1976-1977 from women included in a cohort study in Utrecht and for whom information on smoking status was available. Creatinine and thiocyanate were measured in 1976-1977 on fresh samples. Cotinine and creatinine were analysed in 1988 on urine stored at -20 degrees C. RESULTS: Measurements of creatinine more than 10 years apart showed a correlation of 0.95 and equal means. Cotinine measurements made in 1988 allowed a clear separation of smokers and non-smokers (sensitivity 92%, specificity 100%), suggesting that concentrations retained their discriminant value even after 10 years of storage. CONCLUSION: These results emphasize the possibilities offered by long-term storage, under proper conditions, of biological samples for subsequent determination of analytes which may emerge as the study progresses.

Misclassification of smoking status among women in relation to exposure to environmental tobacco smoke.

In studies of the health effects of exposure to environmental tobacco smoke (ETS), misclassification of active smokers has the potential to bias the estimates of disease risk. Biochemical validation of exposure to ETS can provide objective evidence of current smoking status in epidemiological studies. Intrinsic to this effort is the establishment of appropriate cut-off points for the measurements of tobacco biomarkers. Within a collaborative study on ETS co-ordinated by the International Agency for Research on Cancer, questionnaire data and urine samples were collected from 1,369 women at 13 centres in 10 countries. Forty seven of these women had urine cotinine levels above 50 ng.mg-1 creatinine, a level used to discriminate smokers from nonsmokers in previous studies. The distributions of the subjects across cotinine values and self-reported exposure to ETS was consistent with the association, at one extreme, of moderate cotinine levels (50-150 ng.mg-1) with very high exposure to ETS, and, at the other extreme, of very high cotinine levels indicating actual use of nicotine-containing products in women with low ETS exposure. Using the cut-off point of 150 ng.mg-1, only 1.5% of the alleged nonsmokers were reclassified as current light smokers. Potential bias due to smoker misclassification is very unlikely to be responsible for the increased health risks observed in epidemiological studies on ETS.

Cholesterol screening in a community health promotion program: epidemiologic results from a biracial population.

The prevalence and interrelationship of high blood cholesterol levels with other cardiovascular disease risk factors were studied in a biracial suburb of New York City. Participants in community-based screenings to determine blood cholesterol levels have been predominantly white women in older age groups, highly educated and nonsmokers. To reach a more representative segment of a local population and promote healthy lifestyle behaviors, cholesterol screenings were conducted within an ongoing health promotion program in Mount Vernon, NY. Plasma cholesterol levels were determined for 5,011 participants, including 2,308 whites and 1,778 blacks. Of the men, 29 percent had high cholesterol levels; among women, it was 27 percent. Of the men with high levels, half had levels greater than 200 milligrams per deciliter, as did 55 percent of the women. After statistical adjustments were made for age and other risk factors for high blood cholesterol, mean cholesterol levels were higher for whites than blacks. The level for white men was 204 milligrams per deciliter; for women, 212. For black men, the level was 199 milligrams per deciliter; for women, 208, P < .10. Hispanic men had levels of 199, P < .10. The levels for Hispanic women (203 milligrams per deciliter) were significantly lower than that of white women. Among whites who smoked more than 1 pack of cigarettes per day, mean cholesterol levels were 11 milligrams per deciliter higher than for those who never smoked or were light smokers (0, 1-20 cigarettes per day, P < .10). There were too few who smoked more than 1 pack to test this association adequately among blacks. The mean cholesterol levels for hypertensive black men were 10 milligrams per deciliter greater than for black men with normal blood pressure (P<.10).

Environmental tobacco smoke exposure as determined by cotinine in black and white young adults: the CARDIA Study.

Biologic markers have provided a direct method for assessing exposure to environmental tobacco smoke (ETS) and yet few studies have used these techniques to document exposure in general samples of nonsmokers. Exposure to ETS was assessed by serum cotinine and self-report in 3300 nonsmoking participants in the CARDIA study. Nonsmoking status was validated by a cotinine level of < 14 ng/ml. Twenty-eight percent of the 18- to 30-year-olds were exposed to ETS as determined by a detectable serum cotinine level (2-13 ng/ml); prevalence of exposure was higher among blacks than whites (32% vs 24%, P < 0.001). Similarly, ETS exposure as defined by self-report (hours/week) was higher in blacks, particularly for exposure in the home and in other small areas. Multivariate predictors of cotinine-determined exposure included reported exposure, male gender, lower education, past smoking history, and spending time with smokers. Only among current users of marijuana, 20% of the sample, was the black race found to be an independent predictor of exposure. The prevalence of ETS exposure is higher in blacks than whites, as documented by self-report and confirmed by serum cotinine levels. Other correlates of exposure include demographic factors and factors which may be surrogate measures of exposure.

Measuring exposure to environmental tobacco smoke in studies of acute health effects.

The relations among three methods of measuring exposure to environmental tobacco smoke, questionnaires, urinary cotinine, and a passive monitor for ambient nicotine, were investigated in a study of 48 children in Minnesota in 1989. Subjects were all under 2 years of age and did not attend day care. Passive nicotine monitors were placed in the activity room and the child's bedroom for 1 week, urine samples were collected at the beginning and end of the week for cotinine analysis, and a detailed questionnaire concerning cigarette smoking was administered at the end of the week. These same measures were obtained weekly for 8 weeks for 22 of the children. Among households with smokers, concentrations of ambient nicotine and urinary cotinine were lowest when the father smoked, intermediate when the mother smoked, and highest when both parents smoked. Activity room concentrations were highly correlated with both urinary cotinine (r = 0.81) and the total number of cigarettes smoked in the house (r = 0.86). Regression equations indicated that knowing who smoked in the house was a more important predictor of ambient nicotine than knowing the amount smoked. Both urinary cotinine and ambient nicotine demonstrated variability over time, although ambient nicotine was less variable. In addition, 100% of possible ambient nicotine samples were collected in contrast to 80% of urine samples. The results of the study suggest that both urinary cotinine and ambient nicotine provide better information about the exposure of young children to environmental tobacco smoke than questionnaire data alone, and that ambient nicotine may be the more useful in this population based on its greater stability and ease of collection.

The interaction of sociological and biological factors in adolescent cigarette smoking.

This article considers the interaction of social and biological factors in the context of adolescent cigarette smoking. Parent and peer smoking are the sociological variables and testosterone is the biological indicator. The subjects are 212 males and females 12-14 years of age. The findings support the interaction model, suggesting that both sociological and biological factors are necessary for understanding adolescent smoking.

Passive smoking and middle ear effusion among children in day care.

One hundred thirty-two children who attended a research day-care center were studied to determine whether passive tobacco smoke exposure was associated with an increased rate of otitis media with effusion or with an increased number of days with otitis media with effusion during the first 3 years of life. Based on preliminary studies, a serum cotinine concentration of greater than or equal to 2.5 ng/mL was considered indicative of exposure to tobacco smoke. Otitis media with effusion was diagnosed using pneumatic otoscopy by nurse practitioners and pediatricians who reviewed the children's health status each weekday. The 87 children with serum cotinine concentrations greater than or equal to 2.5 ng/mL had a 38% higher rate of new episodes of otitis media with effusion during the first 3 years of life than the 45 children with lower or undetectable serum cotinine concentrations (incidence density ratio = 1.38, 95% confidence interval 1.21 to 1.56). The average duration of an episode of otitis media with effusion was 28 days in the children with elevated cotinine concentrations and 19 days in the children with lower cotinine concentrations (P less than .01). It is estimated that 8% of the cases of otitis media with effusion in this population and 17.6% of the days with otitis media with effusion may be attributable to exposure to tobacco smoke.

A cholesterol reduction demonstration project: results from a challenge between two cities.

A competition was conducted between Jackson, MS and Lansing, MI to reduce blood cholesterol levels among self-selected individuals who were generally at high risk for elevated coronary heart disease. Baseline plasma cholesterol levels were measured and risk factor data were recorded for 13,710 participants in Jackson and 6,719 in Lansing (6.8% and 5.1% of the total populations, respectively). A six month educational campaign was conducted in both cities which included nutritional seminars, television shows, newspaper advertisements etc. From Jackson, 6,244 participants returned for the follow-up screening, and 2,404 from Lansing (46% and 36%). Subjects who reported changes in their diets had an average cholesterol reduction of 19 mg/dl (9%) in Jackson, and 2 mg/dl (1%) in Lansing (after adjustment for sex, baseline level, and age, P less than 0.01). In Lansing, participants were less likely to have college degrees, and were more likely to have participated because of concern with previously determined elevated cholesterol levels than Jackson participants.

Misclassification of smoking status in the CARDIA study: a comparison of self-report with serum cotinine levels.

BACKGROUND: Although widely used in epidemiological studies, self-report has been shown to underestimate the prevalence of cigarette smoking in some populations. METHODS: In the CARDIA study, self-report of cigarette smoking was validated against a biochemical marker of nicotine uptake, serum cotinine. RESULTS: The prevalence of smoking was slightly lower when defined by self-report (30.9%) than when defined by cotinine levels equal to or greater than 14 ng/mL (32.2%, P less than .05). The misclassification rate (proportion of reported nonsmokers with cotinine levels of at least 14 ng/mL) was 4.2% and was significantly higher among subjects who were Black, had a high school education or less, or were reported former smokers. Possible reasons for misclassification include reporting error, environmental tobacco smoke, and an inappropriate cutoff point for delineation of smoking status. Using self-report as the gold standard, the cotinine cutoff points that maximized sensitivity and specificity were 14, 9, and 15 ng/mL for all, White, and Black subjects, respectively. The misclassification rate remained significantly higher in Black than in White subjects using these race-specific criteria. CONCLUSIONS: Misclassification of cigarette smoking by self-report was low in these young adults; however, within certain race/education groups, self-report may underestimate smoking prevalence by up to 4%.

Passive smoking during the first year of life.

BACKGROUND AND PURPOSE: A description of passive smoking during the first year of life might assist planning preventive efforts. METHODS: Changes in the ecology of passive smoking were investigated in a sample of infants in central North Carolina followed from birth to one year of age. RESULTS: The prevalence of tobacco smoke absorption, indicated by excretion of cotinine, increased from 53 percent to 77 percent (95% CI of difference: 14, 35) during the first year of life. Most infants (92 percent) excreting cotinine at three weeks of age were also excreting it at one year. Moreover, 61 percent of infants not excreting cotinine at age three weeks were excreting it at one year. This increase reflected an increased exposure to household and, particularly, nonhousehold sources of smoke; the proportion of infants exposed to nonhousehold smokers increased from 14 percent to 36 percent. CONCLUSIONS: These findings suggest that prevention of the onset of passive smoking should begin very early.

Diet and serum lipids in vegan vegetarians: a model for risk reduction.

The lipid levels and dietary habits of 31 Seventh-Day Adventist vegan vegetarians (aged 5 to 46 years) who consume no animal products were assessed. Mean serum total cholesterol (3.4 mmol/L), low-density-lipoprotein cholesterol (1.8 mmol/L), and triglyceride (0.8 mmol/L) levels were lower than expected values derived from the Lipid Research Clinics Population Studies prevalence data. Mean high-density-lipoprotein cholesterol (1.3 mmol/L) was comparable to expected values. Analysis of quantitative food frequency data showed that vegans had a significantly lower daily intake of total energy, percentage of energy from fat (31% vs 38%), total fat, saturated fat, monounsaturated fatty acids, cholesterol, and protein and a significantly higher intake of fiber than a sample of matched omnivore controls. Vegans' food intake was also compared with expected values, matched for sex and age, derived from the second National Health and Nutrition Examination Survey and Continuing Survey of Food Intakes by Individuals 24-hour recall data. The vegan diet was characterized by increased consumption of almonds, cashews, and their nut butters; dried fruits; citrus fruits; soy milk; and greens. We conclude from the present study that a strict vegan diet, which is typically very low in saturated fat and dietary cholesterol and high in fiber, can help children and adults maintain or achieve desirable blood lipid levels.