TAS2R bitter taste receptors regulate thyroid function.

Dysregulation of thyroid hormones triiodothyronine and thyroxine (T3/T4) can impact metabolism, body composition, and development. Thus, it is critical to identify novel mechanisms that impact T3/T4 production. We found that type 2 taste receptors (TAS2Rs), which are activated by bitter-tasting compounds such as those found in many foods and pharmaceuticals, negatively regulate thyroid-stimulating hormone (TSH)-dependent Ca(2+) increases and TSH-dependent iodide efflux in thyrocytes. Immunohistochemical Tas2r-dependent reporter expression and real-time PCR analyses reveal that human and mouse thyrocytes and the Nthy-Ori 3-1 human thyrocyte line express several TAS2Rs. Five different agonists for thyrocyte-expressed TAS2Rs reduced TSH-dependent Ca(2+) release in Nthy-Ori 3-1 cells, but not basal Ca(2+) levels, in a dose-dependent manner. Ca(2+) responses were unaffected by 6-n-propylthiouracil, consistent with the expression of an unresponsive variant of its cognate receptor, TAS2R38, in these cells. TAS2R agonists also inhibited basal and TSH-dependent iodide efflux. Furthermore, a common TAS2R42 polymorphism is associated with increased serum T4 levels in a human cohort. Our findings indicate that TAS2Rs couple the detection of bitter-tasting compounds to changes in thyrocyte function and T3/T4 production. Thus, TAS2Rs may mediate a protective response to overingestion of toxic materials and could serve as new druggable targets for therapeutic treatment of hypo- or hyperthyroidism.

The ABCG8 G574R variant, serum plant sterol levels, and cardiovascular disease risk in the Old Order Amish.

OBJECTIVE: To determine whether long-term exposure to moderate elevations in plasma plant sterol levels increases risk for atherosclerosis. METHODS AND RESULTS: In Old Order Amish participants aged 18 to 85 years, with (n=110) and without (n=181) 1 copy of the ABCG8 G574R variant, we compared mean plasma levels of plant sterols and cholesterol precursors and carotid intima-media wall thickness. Carriers of a single 574R allele had increased plant sterol levels (eg, 35%-37% higher plasma levels of sitosterol, campesterol, and stigmasterol) and increased plant sterol/cholesterol ratios (P<0.001 for all). 574R carriers had significantly decreased levels of lathosterol and lanosterol, precursors in a pathway for endogenous cholesterol synthesis, suggesting that plant sterols may alter regulation of genes involved in cholesterol synthesis. The G574R variant was not associated with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol levels. Compared with noncarriers, 574R carriers had decreased carotid intima-media wall thickness (0.62 versus 0.66 mm; age- and sex-adjusted P=0.03). Adjustment for body weight, blood pressure, and standard lipid measures (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides) did not alter this association. CONCLUSIONS: Although the G574R variant is associated with moderately elevated plant sterol levels, carriers of the 574R allele had modestly lower levels of carotid wall thickness compared with noncarriers.

The neuropsychiatry of vitamin B12 deficiency in elderly patients.

Vitamin B12 deficiency is a common cause of neuropsychiatric symptoms in elderly persons. Malabsorption accounts for the majority of cases. Vitamin B12 deficiency has been associated with neurologic, cognitive, psychotic, and mood symptoms, as well as treatment-resistance. Clinician awareness should be raised to accurately diagnose and treat early deficiencies to prevent irreversible structural brain damage, because current practice can be ineffective at identifying cases leading to neuropsychiatric sequelae. This clinical review focuses on important aspects of the recognition and treatment of vitamin B12 deficiency and neuropsychiatric manifestations of this preventable illness in elderly patients.

From the Cover: Whole-genome association study identifies STK39 as a hypertension susceptibility gene.

Hypertension places a major burden on individual and public health, but the genetic basis of this complex disorder is poorly understood. We conducted a genome-wide association study of systolic and diastolic blood pressure (SBP and DBP) in Amish subjects and found strong association signals with common variants in a serine/threonine kinase gene, STK39. We confirmed this association in an independent Amish and 4 non-Amish Caucasian samples including the Diabetes Genetics Initiative, Framingham Heart Study, GenNet, and Hutterites (meta-analysis combining all studies: n = 7,125, P < 10(-6)). The higher BP-associated alleles have frequencies > 0.09 and were associated with increases of 3.3/1.3 mm Hg in SBP/DBP, respectively, in the Amish subjects and with smaller but consistent effects across the non-Amish studies. Cell-based functional studies showed that STK39 interacts with WNK kinases and cation-chloride cotransporters, mutations in which cause monogenic forms of BP dysregulation. We demonstrate that in vivo, STK39 is expressed in the distal nephron, where it may interact with these proteins. Although none of the associated SNPs alter protein structure, we identified and experimentally confirmed a highly conserved intronic element with allele-specific in vitro transcription activity as a functional candidate for this association. Thus, variants in STK39 may influence BP by increasing STK39 expression and consequently altering renal Na(+) excretion, thus unifying rare and common BP-regulating alleles in the same physiological pathway.

Variation in the gene TAS2R38 is associated with the eating behavior disinhibition in Old Order Amish women.

Insensitivity to the bitter-tasting compound 6-n-propylthiouracil (PROP) has been proposed as a marker for individual differences in taste perception that influence food preference and intake. The principal genetic determinants of phenotypic variation in PROP taste sensitivity are alleles of the TAS2R38 gene, which encodes a chemosensory receptor sensitive to thiourea compounds including PROP and phenylthiocarbamide. Members of the TAS2R family are expressed in the gustatory system, where they function as bitter taste receptors, and throughout the gut, where their physiological roles in prandial, gut-derived hormone release are beginning to be elucidated. To better understand the relationship between TAS2R function and ingestive behaviors, we asked if TAS2R38 variants are associated with one or more of three eating behaviors: restraint, disinhibition, and hunger. We genotyped a single nucleotide polymorphism (SNP) located within the TAS2R38 gene, rs1726866 (T785C, Val262Ala) in 729 nondiabetic individuals (381 females, 348 males) within the Amish Family Diabetes Study. Eating behaviors were assessed using the Three-Factor Eating Questionnaire. An association analysis between rs1726866 and these three traits revealed a significant association of the PROP-insensitive "T" allele with increased disinhibition (p=0.03). Because eating behaviors differ substantially between males and females, we subsequently performed sex-stratified analyses, which revealed a strong association in females (p=0.0002) but not in males. Analyses with other SNPs in close proximity to rs1726866 suggest that this locus is principally responsible for the association. Therefore, our results indicate that a polymorphism in TAS2R38 is associated with differences in ingestive behavior.

Increased usual physical activity is associated with a blunting of the triglyceride response to a high-fat meal.

BACKGROUND: Postprandial lipemia (PPL), defined as a prolonged or elevated rise in triglycerides that accompanies fat feeding, is a significant risk factor for coronary heart disease and associated comorbidities. The impact of PPL on coronary heart disease risk is underscored by the preponderance of each day spent in the postprandial state. OBJECTIVE: In this study, we evaluated cross-sectionally the association between usual (ie, noninterventional) physical activity and the 6-hour triglyceride response to a standardized high-fat meal. METHODS: The high-fat meal intervention was carried out in 671 apparently healthy individuals as part of the Heredity and Phenotype Intervention Heart Study. Triglyceride levels were measured in the fasting state and during 6 hours after administration of a standardized fat challenge. We defined PPL response as the triglyceride area under the fat load curve (AUC) and measured physical activity using accelerometers that were worn continuously over a 7-day period. RESULTS: Physical activity levels decreased with increasing age and were higher in men than women (both P < .001). The triglyceride AUC increased with increasing age in both men and women (both P < .001) and was also higher in men than in women (age-adjusted P = 9.2 × 10-12). Higher physical activity levels were associated with a lower triglyceride AUC (P = .003), adjusting for age, sex, body mass index, and fasting low-density lipoprotein. CONCLUSION: These results suggest that the protective benefits of physical activity on cardiovascular health may operate, at least in part, through reduction of the PPL triglyceride response.

Results From a Trial of an Online Diabetes Prevention Program Intervention.

INTRODUCTION: Online Diabetes Prevention Programs (DPPs) can be scaled up and delivered broadly. However, little is known about real-world effectiveness and how outcomes compare with in-person DPP. This study examined online DPP weight loss and participation outcomes and secondarily compared outcomes among participating individuals with parallel in-person interventions. STUDY DESIGN: A large non-randomized trial supplemented by a comparative analysis of participating individuals from a concurrent trial of two parallel in-person programs: in-person DPP and the Veterans Administration's standard of care weight loss program (MOVE!). SETTING/PARTICIPANTS: Obese/overweight Veterans with prediabetes enrolled in online DPP (n = 268) between 2013 and 2014. Similar eligibility criteria were used to enroll in-person participants between 2012 and 2014 (n = 273 in-person DPP, n = 114 MOVE!) within a separate trial. INTERVENTION: Online DPP included a virtual group format, live e-coach, weekly modules delivered asynchronously, and wireless home scales. In-person programs included eight to 22 group-based, face-to-face sessions. MAIN OUTCOMES MEASURES: Weight change at 6 and 12 months using wirelessly uploaded home scale data or electronic medical record weights from clinical in-person visits. Outcomes were analyzed between 2015 and 2017. RESULTS: From 1,182 invitations, 268 (23%) participants enrolled in online DPP. Among these, 158 (56%) completed eight or more modules; mean weight change was -4.7kg at 6 months and -4.0kg at 12 months. In a supplemental analysis of participants completing one or more sessions/modules, online DPP participants were most likely to complete eight or more sessions/modules (87% online DPP vs 59% in-person DPP vs 55% MOVE!, p < 0.001). Online and in-person DPP participants lost significantly more weight than MOVE! participants at 6 and 12 months; there was no significant difference in weight change between online and in-person DPP. CONCLUSIONS: An intensive, multifaceted online DPP intervention had higher participation but similar weight loss compared to in-person DPP. An intensive, multifaceted online DPP intervention may be as effective as in-person DPP and help expand reach to those at risk.

Implementation findings from a hybrid III implementation-effectiveness trial of the Diabetes Prevention Program (DPP) in the Veterans Health Administration (VHA).

BACKGROUND: The Diabetes Prevention Program (DPP) is an effective lifestyle intervention to reduce incidence of type 2 diabetes. However, there are gaps in knowledge about how to implement DPP. The aim of this study was to evaluate implementation of DPP via assessment of a clinical demonstration in the Veterans Health Administration (VHA). METHODS: A 12-month pragmatic clinical trial compared weight outcomes between the Veterans Affairs Diabetes Prevention Program (VA-DPP) and the usual care MOVE!® weight management program (MOVE!). Eligible participants had a body mass index (BMI) ≥30 kg/m2 (or BMI ≥ 25 kg/m2 with one obesity-related condition), prediabetes (glycosylated hemoglobin (HbA1c) 5.7-6.5% or fasting plasma glucose (FPG) 100-125 mg/dL), lived within 60 min of their VA site, and had not participated in a weight management program within the last year. Established evaluation and implementation frameworks were used to guide the implementation evaluation. Implementation barriers and facilitators, delivery fidelity, participant satisfaction, and implementation costs were assessed. Using micro-costing methods, costs for assessment of eligibility and scheduling and maintaining adherence per participant, as well as cost of delivery per session, were also assessed. RESULTS: Several barriers and facilitators to Reach, Adoption, Implementation, Effectiveness and Maintenance were identified; barriers related to Reach were the largest challenge encountered by site teams. Fidelity was higher for VA-DPP delivery compared to MOVE! for five of seven domains assessed. Participant satisfaction was high in both programs, but higher in VA-DPP for most items. Based on micro-costing methods, cost of assessment for eligibility was $68/individual assessed, cost of scheduling and maintaining adherence was $328/participant, and cost of delivery was $101/session. CONCLUSIONS: Multi-faceted strategies are needed to reach targeted participants and successfully implement DPP. Costs for assessing patients for eligibility need to be carefully considered while still maximizing reach to the targeted population.

Diabetes Prevention Program Translation in the Veterans Health Administration.

INTRODUCTION: This clinical demonstration trial compared the effectiveness of the Veterans Affairs Diabetes Prevention Program (VA-DPP) with an evidence-based usual care weight management program (MOVE!®) in the Veterans Health Administration health system. DESIGN: Prospective, pragmatic, non-randomized comparative effectiveness study of two behavioral weight management interventions. SETTING/PARTICIPANTS: Obese/overweight Veterans with prediabetes were recruited from three geographically diverse VA sites between 2012 and 2014. INTERVENTION: VA-DPP included 22 group-based intensive lifestyle change sessions. MAIN OUTCOME MEASURES: Weight change at 6 and 12 months, hemoglobin A1c (HbA1c) at 12 months, and VA health expenditure changes at 15 months were assessed using VA electronic health record and claims data. Between- and within-group comparisons for weight and HbA1c were done using linear mixed-effects models controlling for age, gender, race/ethnicity, baseline outcome values, and site. Analyses were conducted in 2015-2016. RESULTS: A total of 387 participants enrolled (273 VA-DPP, 114 MOVE!). More VA-DPP participants completed at least one (73.3% VA-DPP vs 57.5% MOVE! p=0.002); four (57.5% VA-DPP vs 42.5% MOVE!, p=0.007); and eight or more sessions (42.5% VA-DPP vs 31% MOVE!, p=0.035). Weight loss from baseline was significant at both 6 (p<0.001) and 12 months (p<0.001) for VA-DPP participants, but only significant at 6 months for MOVE! participants (p=0.004). Between groups, there were significant differences in 6-month weight loss (-4.1 kg VA-DPP vs -1.9 kg MOVE!, p<0.001), but not 12-month weight loss (-3.4 kg VA-DPP vs -2.0 kg MOVE!, p=0.16). There were no significant differences in HbA1c change or outpatient, inpatient, and total VA expenditures. CONCLUSIONS: VA-DPP participants had higher participation rates and weight loss at 6 months, but similar weight, HbA1c, and health expenditures at 12 months compared to MOVE! PARTICIPANTS: Features of VA-DPP may help enhance the capability of MOVE! to reach a larger proportion of the served population and promote individual-level weight maintenance.

The CAPN2/CAPN8 Locus on Chromosome 1q Is Associated with Variation in Serum Alpha-Carotene Concentrations.

BACKGROUND/AIMS: Alpha-carotene is a provitamin A carotenoid present in fruits and vegetables. Higher serum concentrations of α-carotene have been associated with lower risk of cancer and all-cause mortality. Previous studies have suggested that genetic variants influence serum concentrations of provitamin A carotenoids, but to date no variants have been robustly associated with serum α-carotene concentrations. The aim of this study was to identify genetic associations with serum α-carotene concentrations using the genome-wide association study (GWAS) approach. METHODS: A GWAS of serum α-carotene concentrations was conducted in 433 Old Order Amish adults who had consumed a 6-day controlled diet. Linear regression models adjusting for age, gender, and family structure were utilized to evaluate associations between genetic variants and serum α-carotene concentrations. RESULTS: Genome-wide significant associations with α-carotene concentrations were observed for loci on chromosome 1q41 between the genes CAPN2 and CAPN8 (rs12137025, p = 3.55 × 10-8), chromosome 2p21 in PRKCE (rs2594495, p = 1.01 × 10-8), and chromosome 4q34 (rs17830069, p = 2.89 × 10-8). CONCLUSIONS: We identified 3 novel loci associated with serum α-carotene concentrations among a population that consumed a controlled diet. While replication is necessary, the CAPN2/CAPN8 locus provides compelling evidence for an association with serum α-carotene concentrations and may suggest a relationship with the development and progression of cancers.

A Common Variant in the SETD7 Gene Predicts Serum Lycopene Concentrations.

Dietary intake and higher serum concentrations of lycopene have been associated with lower incidence of prostate cancer and other chronic diseases. Identifying determinants of serum lycopene concentrations may thus have important public health implications. Prior studies have suggested that serum lycopene concentrations are under partial genetic control. The goal of this research was to identify genetic predictors of serum lycopene concentrations using the genome-wide association study (GWAS) approach among a sample of 441 Old Order Amish adults that consumed a controlled diet. Linear regression models were utilized to evaluate associations between genetic variants and serum concentrations of lycopene. Variant rs7680948 on chromosome 4, located in the intron region of the SETD7 gene, was significantly associated with serum lycopene concentrations (p = 3.41 × 10(-9)). Our findings also provided nominal support for the association previously noted between SCARB1 and serum lycopene concentrations, although with a different SNP (rs11057841) in the region. This study identified a novel locus associated with serum lycopene concentrations and our results raise a number of intriguing possibilities regarding the nature of the relationship between SETD7 and lycopene, both of which have been independently associated with prostate cancer. Further investigation into this relationship might help provide greater mechanistic understanding of these associations.

Variants in the ghrelin gene are associated with metabolic syndrome in the Old Order Amish.

CONTEXT: Mature ghrelin has been shown to stimulate eating and to participate in the regulation of insulin signaling and glucose homeostasis. Its gene, GHRL, is located on chromosome 3 in a region where we have shown linkage to eating behavior, percentage body fat, and total and low-density lipoprotein cholesterol levels in subjects of the Amish Family Diabetes Study. OBJECTIVE: Our objective was to determine whether mutations in GHRL might influence eating behavior and risk for metabolic syndrome, obesity, diabetes, and related traits. DESIGN: We genotyped 856 Amish samples for three missense polymorphisms in GHRL, Arg51Gln, Leu72Met (rs696217), and Gln90Leu (rs4684677) and performed association analyses with eating behavior traits and metabolic syndrome as defined by the National Cholesterol Education Program Adult Treatment Panel III guidelines. SUBJECTS: Our subjects were adult participants in the Amish Family Diabetes Study. RESULTS: The allele frequencies of these variants were 0.03, 0.04, and 0.03, respectively. The prevalence of metabolic syndrome was lower among those carrying the 51Gln allele (3.8 vs. 15.8%; age- and sex-adjusted odds ratio = 0.22; P = 0.031). Hunger scores tended to be lower among 51Gln allele carriers but did not reach statistical significance (P = 0.07). The Leu72Met variant was also associated with increased prevalence of metabolic syndrome (23.2 vs. 13.4%; age- and sex-adjusted odds ratio = 2.57; P = 0.02) as well as higher fasting glucose, lower high-density lipoprotein, and higher triglyceride levels (P = 0.02, P = 0.007, and P = 0.04, respectively). The two variants were not in linkage disequilibrium with each other, suggesting independent effects. We conclude that mutations in GHRL may confer risk for the metabolic syndrome.

Variation in the lamin A/C gene: associations with metabolic syndrome.

OBJECTIVE: Metabolic syndrome is associated with increased risk for cardiovascular disease and type 2 diabetes mellitus (T2DM). The lamin A/C (LMNA) gene, mutations of which cause rare syndromes of severe insulin resistance and dyslipidemia, is located on chromosome 1q21-q24, a region linked to T2DM in several genome wide scans, including in the Old Order Amish. To determine whether polymorphisms in LMNA influence susceptibility to metabolic syndrome and its constituent components. METHODS AND RESULTS: We performed DNA sequence analysis of LMNA. Six single-nucleotide polymorphisms (SNPs) were identified: c.141889C>T (intron 3), c.141906G>T (intron 3), A287A (c.141253T>C; exon 5), c.140353G>A (intron 6), c.139418C>T (intron 8), and H566H (c. 138747C>T; exon 10). In 971 participants from the Amish Family Diabetes Study, the H566H polymorphism of LMNA was associated with metabolic syndrome diagnosed according to National Cholesterol Education Program ATP III criteria and also higher mean fasting triglyceride and lower mean high-density lipoprotein-cholesterol concentrations. However, no differences in allele frequencies were observed for any SNP among participants with T2DM or impaired glucose homeostasis (IGH) and normoglycemic controls. Haplotype analysis showed that >87% of individuals carried 1 of 2 common LMNA haplotypes. There were no significant differences in haplotype frequencies among subjects with metabolic syndrome T2DM, IGH, and controls. CONCLUSIONS: Sequence variation in LMNA may confer modest susceptibility for development of metabolic syndrome and dyslipidemia in the Amish. To determine whether polymorphisms in LMNA influence susceptibility to metabolic syndrome and its constituent components, we performed DNA analysis of polymorphisms in LMNA. The H566H polymorphism was associated with metabolic syndrome and also higher mean fasting triglyceride and lower mean HDL-cholesterol concentrations in the Old Order Amish.

Vitamin and supplement use among old order amish: sex-specific prevalence and associations with use.

BACKGROUND: Complementary and alternative medicine (CAM) in the form of vitamin and supplement use is increasingly prevalent in the United States. The interplay between CAM use and use of conventional medications is not well studied. We examined this issue in Old Order Amish (OOA), a population lacking several factors known to influence supplement use, whose culture and barriers to conventional medications may result in high rates of supplement use. OBJECTIVE: We characterized the patterns of supplement use in OOA, including the extent to which CAM use aggregates in families, and assessed whether higher use of supplements is associated with lower medication use. DESIGN: We conducted a cross-sectional study of conventional medications and supplements in 2,372 adult Amish from the Lancaster County, PA, area. Data were collected through face-to-face interviews. Supplements were subcategorized as herbal vs vitamin/mineral supplements. RESULTS: Seventy-seven percent of all Amish adults reported current supplement use, whereas 22% reported medication use. Women used supplements more often and used more supplements than men, and familial aggregation of supplement use was stronger in family pairs involving women. Supplement use was associated with less medication use after controlling for age, sex, body mass index, and self-reported histories of hypertension, diabetes, and hyperlipidemia (adjusted odds ratio [OR] 0.96, 95% CI 0.92 to 1.00; P=0.047). This association was driven primarily by use of herbal supplements (adjusted OR 0.94, 95% CI 0.89 to 0.99; P=0.025) as vitamin/mineral supplements were not associated with different use of medication (adjusted OR 0.99, 95% CI 0.90 to 1.09; P=0.8). In analyses limited to cardiovascular medications and cardiovascular supplements in participants with hyperlipidemia, hypertension, or diabetes, supplement use was not associated with conventional medication use. CONCLUSIONS: OAA, particularly women, take dietary supplements much more frequently than they use conventional medications. Use of herbal supplements is associated with less use of conventional medications, whereas vitamin/mineral supplement use is not.

Eating behavior in the Old Order Amish: heritability analysis and a genome-wide linkage analysis.

BACKGROUND: Eating behavior and thus dietary intake affect the development of obesity-related diseases such as diabetes, hypertension, and hyperlipidemia. OBJECTIVE: We investigated the genetic underpinnings of eating behavior. DESIGN: We administered a standardized eating behavior inventory to 624 adults from 28 families participating in the Amish Family Diabetes Study. Three quantifiable components of eating behavior were measured: restraint, disinhibition, and hunger. Associations between eating behavior scores and physical characteristics were evaluated. Heritability analysis and a genome-wide multipoint linkage analysis were performed. RESULTS: Eating behavior scores were associated with obesity and obesity-related phenotypes. Heritability estimates were 0.28 +/- 0.09 for restraint, 0.40 +/- 0.10 for disinhibition, and 0.23 +/- 0.09 for hunger (P < 0.001). The linkage analysis showed 4 regions of suggestive linkage. We observed suggestive evidence for linkage of restraint scores to 2 chromosomal regions, near markers D3S1304 [LOD (log of odds) = 2.5, P = 0.0003] and D6S276 (LOD = 2.3, P = 0.0006). We previously reported that D3S1304 is linked to a locus influencing percentage body fat in this same population (LOD = 1.6), suggesting that this behavioral phenotype may be secondary to obesity. The maximum LOD scores for disinhibition were 1.6 (P = 0.003) near marker D7S657 and 1.4 (P = 0.005) near marker D16S752. The maximum LOD score for hunger was 1.4 (P = 0.005) near marker D3S1278. CONCLUSION: Significant familial effects on eating behavior and suggestive genetic linkage were found in Amish adults.

A genome-wide scan of serum lipid levels in the Old Order Amish.

Elevated serum low density lipoprotein cholesterol (LDL-C) and triglyceride (TG) and decreased high density lipoprotein cholesterol (HDL-C) levels are established risk factors for cardiovascular disease (CVD). To identify quantitative trait loci influencing lipid levels, we conducted genome-wide linkage analyses of total serum cholesterol (TSC), HDL-C, ln-transformed TG (LNTG) and LDL-C levels in 612 individuals from 28 families of the Amish Family Diabetes Study (AFDS). Subjects were genotyped for 373 microsatellite markers covering all 22 autosomes and the X chromosome at an average density of 9.7 centimorgans. All lipid traits exhibited moderate estimated heritability (h2 +/- S.E.): TSC, 0.63 +/- 0.11; HDL-C, 0.54 +/- 0.08; LNTG, 0.37 +/- 0.08; LDL-C, 0.62 +/- 0.10. The highest logarithm of the odds (LOD) score observed was 2.47 (P = 0.0003), at 3p25 for LDL-C. LOD scores exceeding 2.0 (P < 0.001) were also observed at 2p23 (LOD = 2.17) and 19p13 (LOD = 2.23) for LDL-C, and at 11q23 (LOD = 2.03) for LNTG. Three additional regions exhibited LOD scores greater than 1.5, corresponding to a P-value of <0.005. Many of the regions suggestively linked in this genome-wide scan contain genes encoding proteins with established roles in lipid metabolism, including apolipoproteins, peroxisome proliferater-activated receptor-gamma and the LDL receptor.

Genetics of eating behavior: established and emerging concepts.

Understanding why we eat and the motivational factors driving food choices is important for addressing the epidemics of obesity, diabetes, and cardiovascular disease. Eating behavior is a complex interplay of physiological, psychological, social, and genetic factors that influence meal timing, quantity of food intake, and food preference. Reviewed here is the current and emerging knowledge of the genetic influences on eating behavior and how these relate to obesity; particular emphasis is placed on the genetics of taste, meal size, and selection, and the emerging use of functional magnetic resonance imaging to study neural reactions in response to food stimuli in normal, overweight, and obese individuals.

Determinants of blood pressure response to low-salt intake in a healthy adult population.

Although the beneficial effects of lowering salt intake in hypertensive patients are widely appreciated, the impact of promoting dietary salt restriction for blood pressure (BP) reduction at the population level remains controversial. The authors used 24-hour ambulatory BP monitoring to characterize the determinants of systolic BP (SBP) response to low-salt intake in a large, relatively healthy Amish population. Patients received a high- and low-sodium diet for 6 days each, separated by a 6- to 14-day washout period. Variance component analysis was used to assess the association of several variables with SBP response to low-salt diet. Mean SBP was 0.7 ± 5.8 mm Hg and 1.3 ± 6.1 mm Hg lower on the low-salt compared with the high-salt diet during daytime (P=.008) and nighttime (P<.0001), respectively. SBP response to a low-salt diet was significantly associated with increasing age and pre-intervention SBP, in both daytime and nighttime, while the association with female sex and SBP response to cold pressor test (CPT) was significant only during nighttime. Our results suggest that salt reduction may have greater BP-lowering effects on women, older individuals, individuals with higher SBP, and individuals with higher SBP response to CPT.

T1R and T2R receptors: the modulation of incretin hormones and potential targets for the treatment of type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM), which is characterized by insulin and glucose dysregulation, is a major contributor to the development of cardiovascular disease, renal failure and premature death. Incretin hormones are released from the intestines upon nutrient ingestion and contribute to glucose homeostasis in part by promoting insulin secretion from the pancreas. Drugs that enhance the incretin response have emerged as effective treatments for T2DM. Several recent studies have revealed that incretin secretion from enteroendocrine cells in the intestines can be modulated by T1R and T2R receptors, proteins that have been demonstrated to function as taste receptors. This review focuses on the intriguing finding that taste receptors may be involved in modulating the incretin response, and considers T1Rs and T2Rs as potential targets for new hypoglycemic drugs.

Bitter taste receptors influence glucose homeostasis.

TAS1R- and TAS2R-type taste receptors are expressed in the gustatory system, where they detect sweet- and bitter-tasting stimuli, respectively. These receptors are also expressed in subsets of cells within the mammalian gastrointestinal tract, where they mediate nutrient assimilation and endocrine responses. For example, sweeteners stimulate taste receptors on the surface of gut enteroendocrine L cells to elicit an increase in intracellular Ca(2+) and secretion of the incretin hormone glucagon-like peptide-1 (GLP-1), an important modulator of insulin biosynthesis and secretion. Because of the importance of taste receptors in the regulation of food intake and the alimentary responses to chemostimuli, we hypothesized that differences in taste receptor efficacy may impact glucose homeostasis. To address this issue, we initiated a candidate gene study within the Amish Family Diabetes Study and assessed the association of taste receptor variants with indicators of glucose dysregulation, including a diagnosis of type 2 diabetes mellitus and high levels of blood glucose and insulin during an oral glucose tolerance test. We report that a TAS2R haplotype is associated with altered glucose and insulin homeostasis. We also found that one SNP within this haplotype disrupts normal responses of a single receptor, TAS2R9, to its cognate ligands ofloxacin, procainamide and pirenzapine. Together, these findings suggest that a functionally compromised TAS2R receptor negatively impacts glucose homeostasis, providing an important link between alimentary chemosensation and metabolic disease.