Biomedical subjects

Richard M Watanabe

Publications and source records attributed to Richard M Watanabe.

16 recordsLinked to original sources

PubMed2026

Lipidomic Profiling Reveals Differential Behaviors of Individual Free Fatty Acids During Altered Metabolic States in Rats.

We used lipidomic analyses to investigate how individual free fatty acids (FFAs) behave differently in metabolic states altered by diet and by antibiotic treatment (ABX) that depletes gut bacteria. Wistar rats were fed either a low-fat or high-fat purified diet, or standard chow with or without antibiotics for two weeks (n = 8-10). Blood samples were then collected before and after meals. Individual FFAs were quantified and grouped based on distinct postprandial response patterns across dietary and treatment conditions. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), key ω-3 FFAs, exhibited postprandial shifts suggestive of suppressed adipocyte lipolysis following meals. Fatty acids in the high-fat diet (HFD) elevated postprandial FFA levels, masking the meal-induced suppression of lipolysis observed with chow or low-fat diet (LFD). Some FFAs, including medium-chain saturated species, remained unaffected by meals. We further evaluated the impact of diet and ABX on baseline (pre-meal) concentrations of FFAs. Certain FFAs were altered by purified diets compared to standard chow. Notably, EPA and DHA were selectively depleted under HFD conditions, likely due to enhanced catabolic activity. In conclusion, lipidomic profiling revealed divergent behaviors among individual FFAs, reflecting distinct metabolic processes and regulatory mechanisms under altered metabolic states.

Animals↗

PubMed2007

Screening of 134 single nucleotide polymorphisms (SNPs) previously associated with type 2 diabetes replicates association with 12 SNPs in nine genes.

More than 120 published reports have described associations between single nucleotide polymorphisms (SNPs) and type 2 diabetes. However, multiple studies of the same variant have often been discordant. From a literature search, we identified previously reported type 2 diabetes-associated SNPs. We initially genotyped 134 SNPs on 786 index case subjects from type 2 diabetes families and 617 control subjects with normal glucose tolerance from Finland and excluded from analysis 20 SNPs in strong linkage disequilibrium (r(2) > 0.8) with another typed SNP. Of the 114 SNPs examined, we followed up the 20 most significant SNPs (P < 0.10) on an additional 384 case subjects and 366 control subjects from a population-based study in Finland. In the combined data, we replicated association (P < 0.05) for 12 SNPs: PPARG Pro12Ala and His447, KCNJ11 Glu23Lys and rs5210, TNF -857, SLC2A2 Ile110Thr, HNF1A/TCF1 rs2701175 and GE117881_360, PCK1 -232, NEUROD1 Thr45Ala, IL6 -598, and ENPP1 Lys121Gln. The replication of 12 SNPs of 114 tested was significantly greater than expected by chance under the null hypothesis of no association (P = 0.012). We observed that SNPs from genes that had three or more previous reports of association were significantly more likely to be replicated in our sample (P = 0.03), although we also replicated 4 of 58 SNPs from genes that had only one previous report of association.

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PubMed2006

Subsets of Finns with high HDL to total cholesterol ratio show evidence for linkage to type 2 diabetes on chromosome 6q.

OBJECTIVES: The purpose of this study was to examine carefully heterogeneity underlying evidence for linkage to type 2 diabetes (T2DM) on chromosome 6q from two sets of FUSION families. METHODS: Ordered subsets analysis (OSA) was performed on two sets of FUSION families. For OSA results showing significant improvement in evidence for linkage, T2DM-related phenotypes were compared between individuals with T2DM within the subset versus the complement. RESULTS: OSA analysis revealed 105 families with the highest average HDL to total cholesterol ratio (HDL ratio) that had strongly increased evidence for linkage (MLS = 7.91 at 78.0 cM; uncorrected p = 0.00002). Subjects with T2DM within this subset were significantly leaner, had lower fasting glucose, insulin, and C-peptide, and more favorable cardiovascular risk profile compared to the complement set of subjects with T2DM. OSA also revealed 33 families with the lowest average fasting insulin that had increased evidence for linkage at a second locus (MLS = 3.45 at 128 cM; uncorrected p = 0.017) coincident with quantitative trait locus linkage analysis results for fasting and 2-hour insulin in subjects without T2DM. CONCLUSIONS: These results suggest two diabetes susceptibility loci on chromosome 6q that may affect subsets of individuals with a milder form of T2DM.

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PubMed2006

Common variants in maturity-onset diabetes of the young genes contribute to risk of type 2 diabetes in Finns.

Prior reports have suggested that variants in the genes for maturity-onset diabetes of the young (MODY) may confer susceptibility to type 2 diabetes, but results have been conflicting and coverage of the MODY genes has been incomplete. To complement our previous studies of HNF4A, we examined the other five known MODY genes for association with type 2 diabetes in Finnish individuals. For each of the five genes, we selected 1) nonredundant single nucleotide polymorphisms (SNPs) (r(2)< 0.8 with other SNPs) from the HapMap database or another linkage disequilibrium map, 2) SNPs with previously reported type 2 diabetes association, and 3) nonsynonymous coding SNPs. We tested 128 SNPs for association with type 2 diabetes in 786 index cases from type 2 diabetic families and 619 normal glucose-tolerant control subjects. We followed up 35 of the most significant SNPs by genotyping them on another 384 case subjects and 366 control subjects from Finland. We also supplemented our previous HNF4A results by genotyping 12 SNPs on additional Finnish samples. After correcting for testing multiple correlated SNPs within a gene, we find evidence of type 2 diabetes association with SNPs in five of the six known MODY genes: GCK, HNF1A, HNF1B, NEUROD1, and HNF4A. Our data suggest that common variants in several MODY genes play a modest role in type 2 diabetes susceptibility.

Basic Helix-Loop-Helix Proteins↗

PubMed2005

Mitochondrial polymorphisms and susceptibility to type 2 diabetes-related traits in Finns.

Mitochondria play an integral role in ATP production in cells and are involved in glucose metabolism and insulin secretion, suggesting that variants in the mitochondrial genome may contribute to diabetes susceptibility. In a study of Finnish families ascertained for type 2 diabetes mellitus (T2DM), we genotyped single nucleotide polymorphisms (SNPs) based on phylogenetic networks. These SNPs defined eight major haplogroups and subdivided groups H and U, which are common in Finns. We evaluated association with both diabetes disease status and up to 14 diabetes-related traits for 762 cases, 402 non-diabetic controls, and 465 offspring of genotyped females. Haplogroup J showed a trend toward association with T2DM affected status (OR 1.69, P=0.056) that became slightly more significant after excluding cases with affected fathers (OR 1.77, P=0.045). We also genotyped non-haplogroup-tagging SNPs previously reported to show evidence for association with diabetes or related traits. Our data support previous evidence for association of T16189C with reduced ponderal index at birth and also show evidence for association with reduced birthweight but not with diabetes status. Given the multiple tests performed and the significance levels obtained, this study suggests that mitochondrial genome variants may play at most a modest role in glucose metabolism in the Finnish population. Furthermore, our data do not support a reported maternal inheritance pattern of T2DM but instead show a strong effect of recall bias.

Adenosine Triphosphate↗

PubMed2005

Impact of ABCB1 (MDR1) haplotypes on tacrolimus dosing in adult lung transplant patients who are CYP3A5 3/3 non-expressors.

BACKGROUND: The influence of ABCB1 (MDR1) polymorphisms on tacrolimus dosing has been questioned in previous studies with contradictory findings, possibly due to the association between CYP3A5 polymorphisms and tacrolimus dosing. The objective of this study was to assess the effect of ABCB1 haplotypes from 3 distinct polymorphic sites on the tacrolimus level/dose [L/D] in lung transplant patients limited to CYP3A5 *3/*3 non-expressors. METHOD: A total of 91 lung transplant patients treated primarily with tacrolimus and prednisone were enrolled, and clinical information on drug dosing and blood levels was collected. The [L/D] was calculated for patients receiving tacrolimus at 1, 3, 6, 9 and 12 months post transplant. ABCB1 polymorphisms at C1236T, G2677T, and C3435T were assessed by PCR amplification and DNA sequencing. Haplotypes were estimated by Arlequin ver.2.00. Haplotype effects on tacrolimus [L/D] were assessed by two-way ANOVA. RESULTS: Of the 10 haplotypes, CGC, TTT and CGT accounted for 44.1%, 40.7% and 7.6% of the total haplotypes, respectively. The tacrolimus [L/D] value in the CGC-CGC patients was significantly lower than in patients with CGC-TTT and TTT-TTT genotypes at the first month (mean [L/D]=1.45 versus 3.10 and 3.97 ngxmL(-)(1) /mg/day), and throughout the first post transplant year. CONCLUSION: This study demonstrates that ABCB1 haplotypes derived from three common polymorphisms are associated with tacrolimus dosing in lung transplant patients when eliminating the confounder CYP3A5 genotype.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2005

Sequence variation in PPARG may underlie differential response to troglitazone.

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor-gamma (PPARG) agonists used to treat type 2 diabetes. TZDs can also be used to reduce rates of type 2 diabetes in at-risk individuals. However, a large fraction of TZD-treated patients (30-40%) do not respond to TZD treatment with an improvement in insulin sensitivity (Si). We hypothesized that variation within the gene encoding PPARG may underlie this differential response to TZD therapy. We screened approximately 40 kb of PPARG in 93 nondiabetic Hispanic women (63 responders and 30 nonresponders) with previous gestational diabetes who had participated in the Troglitazone In the Prevention Of Diabetes study. TZD nonresponse was defined as the lower tertile in change in Si after 3 months of treatment. Baseline demographic and clinical measures were not different between responders and nonresponders. We identified and genotyped 131 variants including 126 single nucleotide polymorphisms and 5 insertion-deletion polymorphisms. Linkage disequilibrium analysis identified five haplotype blocks. Eight variants were associated with TZD response (P < 0.05). Three variants were also associated with changes in Si as a continuous variable. Our results suggest that PPARG variation may underlie response to TZD therapy in women at risk for type 2 diabetes.

Adult↗

PubMed2004

Ordered subset analysis in genetic linkage mapping of complex traits.

Etiologic heterogeneity is a fundamental feature of complex disease etiology; genetic linkage analysis methods to map genes for complex traits that acknowledge the presence of genetic heterogeneity are likely to have greater power to identify subtle changes in complex biologic systems. We investigate the use of trait-related covariates to examine evidence for linkage in the presence of heterogeneity. Ordered-subset analysis (OSA) identifies subsets of families defined by the level of a trait-related covariate that provide maximal evidence for linkage, without requiring a priori specification of the subset. We propose that examining evidence for linkage in the subset directly may result in a more etiologically homogeneous sample. In turn, the reduced impact of heterogeneity will result in increased overall evidence for linkage to a specific region and a more distinct lod score peak. In addition, identification of a subset defined by a specific trait-related covariate showing increased evidence for linkage may help refine the list of candidate genes in a given region and suggest a useful sample in which to begin searching for trait-associated polymorphisms. This method provides a means to begin to bridge the gap between initial identification of linkage and identification of the disease predisposing variant(s) within a region when mapping genes for complex diseases. We illustrate this method by analyzing data on breast cancer age of onset and chromosome 17q [Hall et al., 1990, Science 250:1684-1689]. We evaluate OSA using simulation studies under a variety of genetic models.

Breast Neoplasms↗

PubMed2004

A large set of Finnish affected sibling pair families with type 2 diabetes suggests susceptibility loci on chromosomes 6, 11, and 14.

The aim of the Finland-United States Investigation of NIDDM Genetics (FUSION) study is to identify genes that predispose to type 2 diabetes or are responsible for variability in diabetes-related traits via a positional cloning and positional candidate gene approach. In a previously published genome-wide scan of 478 Finnish affected sibling pair (ASP) families (FUSION 1), the strongest linkage results were on chromosomes 20 and 11. We now report a second genome-wide scan using an independent set of 242 Finnish ASP families (FUSION 2), a detailed analysis of the combined set of 737 FUSION 1 + 2 families (495 updated FUSION 1 families), and fine mapping of the regions of chromosomes 11 and 20. The strongest FUSION 2 linkage results were on chromosomes 6 (maximum logarithm of odds score [MLS] = 2.30 at 95 cM) and 14 (MLS = 1.80 at 57 cM). For the combined FUSION 1 + 2 families, three results were particularly notable: chromosome 11 (MLS = 2.98 at 82 cM), chromosome 14 (MLS = 2.74 at 58 cM), and chromosome 6 (MLS = 2.66 at 96 cM). We obtained smaller FUSION 1 + 2 MLSs on chromosomes X (MLS = 1.27 at 152 cM) and 20p (MLS = 1.21 at 20 cM). Among the 10 regions that showed nominally significant evidence for linkage in FUSION 1, four (on chromosomes 6, 11, 14, and X) also showed evidence for linkage in FUSION 2 and stronger evidence for linkage in the combined FUSION 1 + 2 sample.

Age of Onset↗

PubMed2004

Genetic variation near the hepatocyte nuclear factor-4 alpha gene predicts susceptibility to type 2 diabetes.

The Finland-United States Investigation Of NIDDM Genetics (FUSION) study aims to identify genetic variants that predispose to type 2 diabetes by studying affected sibling pair families from Finland. Chromosome 20 showed our strongest initial evidence for linkage. It currently has a maximum logarithm of odds (LOD) score of 2.48 at 70 cM in a set of 495 families. In this study, we searched for diabetes susceptibility variant(s) at 20q13 by genotyping single nucleotide polymorphism (SNP) markers in case and control DNA pools. Of 291 SNPs successfully typed in a 7.5-Mb interval, the strongest association confirmed by individual genotyping was with SNP rs2144908, located 1.3 kb downstream of the primary beta-cell promoter P2 of hepatocyte nuclear factor-4 alpha (HNF4A). This SNP showed association with diabetes disease status (odds ratio [OR] 1.33, 95% CI 1.06-1.65, P = 0.011) and with several diabetes-related traits. Most of the evidence for linkage at 20q13 could be attributed to the families carrying the risk allele. We subsequently found nine additional associated SNPs spanning a 64-kb region, including the P2 and P1 promoters and exons 1-3. Our results and the independent observation of association of SNPs near the P2 promoter with diabetes in a separate study population of Ashkenazi Jewish origin suggests that variant(s) located near or within HNF4A increases susceptibility to type 2 diabetes.

Basic Helix-Loop-Helix Leucine Zipper Transcriptio↗

PubMed2004

Changes in insulin sensitivity in response to troglitazone do not differ between subjects with and without the common, functional Pro12Ala peroxisome proliferator-activated receptor-gamma2 gene variant: results from the Troglitazone in Prevention of Diabetes (TRIPOD) study.

OBJECTIVE: We have tested whether the Pro12Ala variant of the peroxisome proliferator-activated receptor (PPAR)-gamma nuclear receptor involved in thiazolidinedione (TZD) action accounted for the failure of troglitazone to increase insulin sensitivity in nondiabetic Hispanic women with previous gestational diabetes treated in the Troglitazone in Prevention of Diabetes (TRIPOD) study. RESEARCH DESIGN AND METHODS: Ninety-three women assigned to troglitazone had intravenous glucose tolerance tests at randomization and after 3 months of treatment with troglitazone, 400 mg/day, and were genotyped for the Pro12Ala variant of the PPAR-gamma gene. Subjects were divided into tertiles based on their change in minimal model insulin sensitivity (S(i)) during the first 3 months of troglitazone treatment. RESULTS: The mean changes in S(i) in the bottom, middle, and top tertiles of S(i) response were -0.21 +/- 0.57, 0.91 +/- 0.26, and 2.58 +/- 1.32 min(-1) per microU/ml. 10(-4), respectively. Frequencies of the Ala/- genotype were 30, 22, and 26% in the same three tertiles (P = 0.77). Analysis of phenotypes by genotype revealed only small differences between the Pro/Pro and Ala/- groups, respectively, in baseline S(i) (2.76 +/- 0.19 vs. 2.33 +/- 0.33 x 10(-4) min(-1) per microU/ml; P = 0.27), the change in S(i) after 3 months of troglitazone treatment (1.19 +/- 0.17 vs. 0.93 +/- 0.30; P = 0.46), and the cumulative incidence of diabetes during a median follow-up of 30 months (13 vs. 17%; P = 0.66). CONCLUSIONS: Among young Hispanic women at high risk for type 2 diabetes, the Pro12Ala variant of the PPAR-gamma receptor gene did not explain the failure of approximately 1/3 of subjects to increase their insulin sensitivity when placed on troglitazone at a dose of 400 mg/day.

Alanine↗

PubMed2004

Acute alcohol consumption improves insulin action without affecting insulin secretion in type 2 diabetic subjects.

OBJECTIVE: Long-term exposure to alcohol is associated with an improvement in insulin sensitivity. At this time, however, there is no definitive proof that alcohol per se has an effect on the insulin sensitivity index (S(i)) in type 2 diabetes patients. The aim of the present study was to assess the role of acute moderate alcohol intake on insulin sensitivity and insulin secretion in comparable subjects with and without type 2 diabetes. RESEARCH DESIGN AND METHODS: Frequently sampled intravenous glucose tolerance tests (FSIGTs) were performed twice on eight healthy and eight type 2 diabetic volunteers. Forty grams of alcohol (vodka 40% wt/vol) or tap water were sipped from time -60 min to the end of the FSIGT. RESULTS: Lactate area under the curve (AUC) was higher in both groups during the alcohol study than in the control study. Free fatty acid (FFA) AUC was higher in type 2 diabetic subjects than in control subjects; alcohol slightly reduced FFA by 17% in control subjects (34 +/- 4 mmol. min(-1). l(-1); P = 0.1) but significantly decreased FFA by 23% in type 2 diabetic subjects (54 +/- 10; P = 0.007). Beta-cell response was markedly reduced in type 2 diabetic subjects regardless of the type of study. Alcohol significantly increased S(i) in both groups. CONCLUSIONS: Acute alcohol consumption improves insulin action without affecting beta-cell secretion. This effect may be partly due to the inhibitory effect of alcohol on lipolysis. Alcohol intake increases insulin sensitivity and may partly explain both the J-shaped relationship between the prevalence of diabetes and the amount of alcohol consumption and the decreased mortality for myocardial infarction.

Aged↗

PubMed2003

MINMOD Millennium: a computer program to calculate glucose effectiveness and insulin sensitivity from the frequently sampled intravenous glucose tolerance test.

The Bergman Minimal Model enables estimation of two key indices of glucose/insulin dynamics: glucose effectiveness and insulin sensitivity. In this paper we describe MINMOD Millennium, the latest Windows-based version of minimal model software. Extensive beta testing of MINMOD Millennium has shown that it is user-friendly, fully automatic, fast, accurate, reproducible, repeatable, and highly concordant with past versions of MINMOD. It has a simple interface, a comprehensive help system, an input file editor, a file converter, an intelligent processing kernel, and a file exporter. It provides publication-quality charts of glucose and insulin and a table of all minimal model parameters and their error estimates. In contrast to earlier versions of MINMOD and some other minimal model programs, Millennium provides identified estimates of insulin sensitivity and glucose effectiveness for almost every subject.

Blood Glucose↗

PubMed2003

Minimal model-based insulin sensitivity has greater heritability and a different genetic basis than homeostasis model assessment or fasting insulin.

Insulin resistance is an important risk factor for development of type 2 diabetes as well as other chronic conditions, including hypertension, cardiovascular disease, and colon cancer. To find genes for insulin resistance it is necessary to assess insulin action in large populations. We have previously measured insulin action in a large cohort of subjects (Insulin Resistance and Atherosclerosis Study [IRAS] Family Study) using the minimal model approach. In this study, we compare sensitivity from the minimal model (insulin sensitivity index [S(I)]) with the measure of insulin resistance emanating from the homeostasis model assessment (HOMA) approach. The former measure emerges from the glycemic response to endogenous and exogenous insulin; the latter is based solely on fasting measures of glucose and insulin. A total of 112 pedigrees were represented, including 1,362 individuals with full phenotypic assessment. Heritability of S(I) was significantly greater than that for HOMA (0.310 vs. 0.163) and for fasting insulin (0.171), adjusted for age, sex, ethnicity, and BMI. In addition, correlation between S(I) and either HOMA or fasting insulin was only approximately 50% accounted for by genetic factors, with the remainder accounted for by environment. Thus S(I), a direct measure of insulin sensitivity, is determined more by genetic factors rather than measures such as HOMA, which reflect fasting insulin.

Adult↗

PubMed2002

Glucose tolerance during moderate alcohol intake: insights on insulin action from glucose/lactate dynamics.

Moderate alcohol (ETOH) intake has been associated with a significant reduction in risk for infarction among general populations. In this study, we assessed the effects of low-dose ETOH (40 g over 3-h period as vodka) on the interaction between glucose (G), insulin, and lactate (L) during the insulin-modified frequently sampled i.v. glucose tolerance test (FSIGT) (0.3 U/kg body weight between 20-25 min) in eight normal volunteers. In the control (C) study, water was administered. An insulin-independent two-compartment model was used to describe G and L kinetics. Insulin sensitivity (S(I)) was significantly higher in the ETOH study than in the C study (2.49 +/- 0.52 vs. 0.92 +/- 0.20 10(-4) min(-1)microU(-1)ml, C vs. ETOH; P = 0.0391). No significant differences were observed in G effectiveness (0.029 +/- 0.004 vs. 0.033 +/- 0.004 min(-1)). Blood L levels were higher during FSIGT when ETOH was administered [area under the curve (AUC), 201 plus minus 16 vs. 123 +/- 23 mmol/liter in 240 min; P = 0.0001]. The dynamic analysis of blood L concentrations showed that ETOH also significantly decreased L clearance (0.0016 +/- 0.0011 vs. 0.0029 +/- 0.0002 min(-1); P = 0.0156), whereas no difference was observed for the fractional conversion of the rate of G disappearance to L (0.0033 +/- 0.0012 vs. 0.0031 +/- 0.0005 min(-1)). ETOH decreased baseline plasma FFA concentration; AUC of FFA was markedly reduced with ETOH (65 +/- 14 vs. 109 plus minus 17 mmol/liter in 240 min; P = 0.0063) and inversely correlated with S(I) (r = 0.693; P = 0.0029). The amount of C-peptide in 240 min as well as the amounts before and after insulin administration were not different between the two tests. We concluded that G and L kinetics derived from FSIGT shows that moderate ETOH intake: 1) improves insulin action; 2) decreases L clearance; and 3) does not affect beta cell function. Because ETOH at moderate doses has a marked antilipolytic action, it might improve insulin action by improving substrate competition. The present findings suggest that moderate alcohol consumption in the diet should not be discouraged.

Adult↗

PubMed2002

Variation in three single nucleotide polymorphisms in the calpain-10 gene not associated with type 2 diabetes in a large Finnish cohort.

Variations in the calpain-10 gene have recently been reported to be associated with type 2 diabetes in a Mexican-American population. We typed three single nucleotide polymorphisms (SNPs) in the calpain-10 gene (SNPs 43, 56, and 63) to test for association between variation at these loci and type 2 diabetes and diabetes-related traits in 1,603 Finnish subjects: two samples of 526 (Finland-U.S. Investigation of NIDDM Genetics [FUSION] 1) and 255 (FUSION 2) index case subjects with type 2 diabetes, 185 and 414 unaffected spouses and offspring of FUSION 1 index case subjects or their affected siblings, and 223 elderly normal glucose-tolerant control subjects. We found no significant differences in allele, genotype, haplotype, or haplogenotype frequencies between index case subjects with diabetes and the elderly and spouse control populations (all P > 0.087). Although variation in these three SNPs was associated with variation in some type 2 diabetes-related traits within each of the case and control groups, no consistent pattern of the implicated variant or combination of variants was discerned. We conclude that variation in these three SNPs in the calpain-10 gene is unlikely to confer susceptibility to type 2 diabetes in this Finnish cohort.

Aged↗