A prospective cohort analysis of gut microbial co-metabolism in Alaska Native and rural African people at high and low risk of colorectal cancer.

BACKGROUND: Alaska Native (AN) people have the world's highest recorded incidence of sporadic colorectal cancer (CRC) (∼91:100,000), whereas rural African (RA) people have the lowest risk (<5:100,000). Previous data supported the hypothesis that diet affected CRC risk through its effects on the colonic microbiota that produce tumor-suppressive or -promoting metabolites. OBJECTIVES: We investigated whether differences in these metabolites may contribute to the high risk of CRC in AN people. METHODS: A cross-sectional observational study assessed dietary intake from 32 AN and 21 RA healthy middle-aged volunteers before screening colonoscopy. Analysis of fecal microbiota composition by 16S ribosomal RNA gene sequencing and fecal/urinary metabolites by 1H-NMR spectroscopy was complemented with targeted quantification of fecal SCFAs, bile acids, and functional microbial genes. RESULTS: Adenomatous polyps were detected in 16 of 32 AN participants, but not found in RA participants. The AN diet contained higher proportions of fat and animal protein and less fiber. AN fecal microbiota showed a compositional predominance of Blautia and Lachnoclostridium, higher microbial capacity for bile acid conversion, and low abundance of some species involved in saccharolytic fermentation (e.g., Prevotellaceae, Ruminococcaceae), but no significant lack of butyrogenic bacteria. Significantly lower concentrations of tumor-suppressive butyrate (22.5 ± 3.1 compared with 47.2 ± 7.3 SEM µmol/g) coincided with significantly higher concentrations of tumor-promoting deoxycholic acid (26.7 ± 4.2 compared with 11 ± 1.9 µmol/g) in AN fecal samples. AN participants had lower quantities of fecal/urinary metabolites than RA participants and metabolite profiles correlated with the abundance of distinct microbial genera in feces. The main microbial and metabolic CRC-associated markers were not significantly altered in AN participants with adenomatous polyps. CONCLUSIONS: The low-fiber, high-fat diet of AN people and exposure to carcinogens derived from diet or environment are associated with a tumor-promoting colonic milieu as reflected by the high rates of adenomatous polyps in AN participants.

Cardiometabolic correlates of low type 2 diabetes incidence in western Alaska Native people - The WATCH study.

AIMS: Previously rare among Alaska Native (AN) people, type 2 diabetes (DM2) prevalence as indicated by registry data has increased by as much as 300% in some western Alaska regions. We sought to determine prevalence and incidence of DM2 and analyze associated cardiometabolic risk factors in western AN people. METHODS: DM2 and prediabetes prevalence and incidence were determined by the Western Alaska Tribal Collaborative for Health using consolidated data from cohort studies conducted during 2000-2010. Crude and age-adjusted incidence for DM2 and prediabetes were calculated using 2010 American Diabetes Association criteria. Effects of covariates on DM2 and prediabetes were determined using univariate and multivariate Cox proportional hazards analyses, adjusted for age and sex. RESULTS: Excluding baseline diabetes (n=124, 4.5%), 53 cases of new DM2 were identified among 2630 participants. Age- and sex-adjusted DM2 incidence was 4.3/1000 (95% CI 2.9, 5.0) person-years over an average 5.9-year follow up. After excluding baseline prediabetes, 387 new cases of prediabetes were identified among 1841 participants; adjusted prediabetes incidence was 44.5/1000 (95% CI 39.5, 49.5) person years. Independent predictors for DM2 included age, impaired fasting glucose, and metabolic syndrome; family history of diabetes and obesity were additional independent predictors for prediabetes. CONCLUSIONS: DM2 incidence in western AN people is substantially lower than that for U.S. whites; however, incidence of prediabetes is more than 10-fold higher than western AN DM2 incidence and more closely aligned with U.S. rates. Interventions aimed at achieving healthy lifestyles are needed to minimize risk factors and maximize protective factors for DM2 in this population.

Agreement Between Self-Report and Medical Record Prevalence of 16 Chronic Conditions in the Alaska EARTH Study.

The gold standard for health information is the health record. Hospitalization and outpatient diagnoses provide health systems with data on which to project health costs and plan programmatic changes. Although health record information may be reliable and perceived as accurate, it may not include population-specific information and may exclude care provided outside a specific health care facility. Sole reliance on medical record information may lead to underutilization of health care services and inadequate assessment of population health status. In this study, we analyzed agreement, without assuming a gold standard, between self-reported and recorded chronic conditions in an American Indian/Alaska Native cohort. Self-reported health history was collected from 3821 adult participants of the Alaska EARTH study during 2004-2006. Participant medical records were electronically accessed and reviewed. Self-reported chronic conditions were underreported in relation to the medical record and both information sources reported the absence more reliably than the presence of conditions (across conditions, median positive predictive value = 64%, median negative predictive value = 94%). Agreement was affected by age, gender, and education. Differences between participant- and provider-based prevalence of chronic conditions demonstrate why health care administrators and policy makers should not rely exclusively on medical record-based administrative data for a comprehensive evaluation of population health.

Citizen Science Reveals an Extensive Shift in the Winter Distribution of Migratory Western Grebes.

Marine waterbirds have shown variable trends in abundance over the past four decades with some species displaying steep declines along the Pacific coast from British Columbia through California. One of the most dramatic changes has been that of western grebes (Aechmophorus occidentalis) in the Salish Sea. This region was a former core of the species wintering distribution but they have become increasingly rare prompting calls for conservation action. A more thorough understanding of this situation requires the analysis of trends at broader geographic scales as well as a consideration of mechanisms that might have led to a change in abundance. We used hierarchical modeling with a Bayesian framework applied to 36 years of Audubon Christmas Bird Count data to assess continent-wide and regional population trends in western and Clark's grebes (A. clarkii) from 1975 to 2010. Our results show that the North American wintering population of Aechmophorus grebes decreased by ∼52% after 1975, but also that western grebes displayed strongly opposing regional patterns. Abundance decreased by about 95% over 36 years in the Salish Sea but increased by over 300% along coastal California. As a result, the mean centre of the species distribution shifted south by an estimated 895 km between 1980 and 2010. Mechanisms underlying this shift require further study but we hypothesize that it may be related to a change in the abundance and availability of their forage fish prey base. Since the mid-1980s, the Pacific sardine stock off the California coast increased from a few thousand metric tonnes to over two million. At the same time both the abundance and availability of Pacific herring declined in the Salish Sea. Studies are needed to examine this hypothesis further and additional consideration should be directed at other changes in the marine environment that may have contributed to a range shift.

Temporal patterns of genetic diversity in Kirtland's warblers (Dendroica kirtlandii), the rarest songbird in North America.

BACKGROUND: Kirtland's warblers are the rarest songbird species in North America, rarity due in part to a reliance on early successional Jack Pine forests. Habitat loss due to fire suppression led to population declines to fewer than 200 males during the 1970s. Subsequent conservation management has allowed the species to recover to over 1700 males by 2010. In this study, we directly examine the impact that low population sizes have had on genetic variation in Kirtland's warblers. We compare the molecular variation of samples collected in Oscoda County, Michigan across three time periods: 1903-1912, 1929-1955 and 2008-2009. RESULTS: In a hierarchical rarified sample of 20 genes and one time period, allelic richness was highest in 1903-1912 sample (A(R) = 5.96), followed by the 1929-1955 sample (A(R) = 5.74), and was lowest in the 2008-2009 sample (A(R) = 5.54). Heterozygosity measures were not different between the 1929-1955 and 2008-2009 samples, but were lower in the 1903-1912 sample. Under some models, a genetic bottleneck signature was present in the 1929-1955 and 2008-2009 samples but not in the 1903-1912 sample. CONCLUSIONS: We suggest that these temporal genetic patterns are the result of the declining Kirtland's warbler population compressing into available habitat and a consequence of existing at low numbers for several decades.