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Search Results: 1 - 10 of 201851 matches for " Ambika P. Ashraf "
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Macronutrient Intake Influences the Effect of 25-Hydroxy-Vitamin D Status on Metabolic Syndrome Outcomes in African American Girls
Anna L. Newton,Lynae J. Hanks,Ambika P. Ashraf,Elizabeth Williams,Michelle Davis,Krista Casazza
Cholesterol , 2012, DOI: 10.1155/2012/581432
Abstract: The objectives were to determine the effect of macronutrient modification on vitamin D status and if change in 25-hydroxy-vitamin D concentration influences components of metabolic syndrome in obese African American girls. Methods. Five-week intervention using reduced CHO (43% carbohydrate; 27% fat: SPEC) versus standard CHO (55% carbohydrate; 40% fat: STAN) eucaloric diet. Subjects were 28 obese African American females, aged 9–14 years. Dual energy X-ray absorptiometry and meal test were performed at baseline and five weeks. Results. Approximately 30% of girls had metabolic syndrome. Serum 25OHD increased in both groups at five weeks [STAN: 20.3 ± 1.1 to 22.4 ± 1.1 (<0.05) versus SPEC: 16.1±1.0 to 16.8±1.0 (=0.05)]. The STAN group, increased 25OHD concentration over five weeks (<0.05), which was positively related to triglycerides (<0.001) and inversely associated with total cholesterol (<0.001) and LDL (<0.001). The SPEC group, had increase in 25OHD (=0.05), which was positively related to fasting insulin (<0.001) and insulin sensitivity while inversely associated with fasting glucose (<0.05). The contribution of vitamin D status to metabolic syndrome parameters differs according to macronutrient intake. Improvement in 25OHD may improve fasting glucose, insulin sensitivity, and LDL; however, macronutrient intake warrants consideration.
Dietary iron intake in the first 4 months of infancy and the development of type 1 diabetes: a pilot study
Ambika P Ashraf, Nancy B Eason, Edmond K Kabagambe, Josna Haritha, Sreelatha Meleth, Kenneth L McCormick
Diabetology & Metabolic Syndrome , 2010, DOI: 10.1186/1758-5996-2-58
Abstract: Case-control study with self-administered questionnaire among families of children with T1DM who were less than 10 years old at the time of the survey and developed diabetes between age 1 and 6 years. Data on the types of infant feeding in the first 4 months of life was collected from parents of children with T1DM (n = 128) and controls (n = 67) <10 years old. Because some cases had sibling controls, we used conditional logistic regression models to analyze the data in two ways. First we performed a case-control analysis of all 128 cases and 67 controls. Next, we performed a case-control analysis restricted to cases (n = 59) that had a sibling without diabetes (n = 59). Total iron intake was modeled as one standard deviation (SD) increase in iron intake. The SD for iron intake was 540 mg in the total sample and 539 mg in the restricted sample as defined above.The median (min, max) total iron intake in the first 4 months of life was 1159 (50, 2399) mg in T1DM cases and 466 (50, 1224) mg among controls (P < 0.001). For each one standard deviation increase in iron intake, the odds ratio (95% confidence interval) for type 1 diabetes was 2.01 (1.183, 3.41) among all participants (128 cases and 67 controls) while it was 2.26 (1.27, 4.03) in a restricted sample of T1 D cases with a control sibling (59 cases and 59 controls) in models adjusted for birth weight, age at the time of the survey, and birth order.In this pilot study, high iron intake in the first 4 months of infancy is associated with T1DM. Whether iron intake is causal or a marker of another risk factor warrants further investigation.The incidence of type 1 diabetes (T1DM) is increasing worldwide and the age of onset is shifting downwards with a significant number of cases occurring between birth and 4 years of age [1-4]. Although the causes for increased incidence and early onset of T1DM are uncertain [1], a number of risk factors associated with induction of autoimmunity in the genetically susceptible individu
Macronutrient Intake Influences the Effect of 25-Hydroxy-Vitamin D Status on Metabolic Syndrome Outcomes in African American Girls
Anna L. Newton,Lynae J. Hanks,Ambika P. Ashraf,Elizabeth Williams,Michelle Davis,Krista Casazza
Cholesterol , 2012, DOI: 10.1155/2012/581432
Abstract: The objectives were to determine the effect of macronutrient modification on vitamin D status and if change in 25-hydroxy-vitamin D concentration influences components of metabolic syndrome in obese African American girls. Methods. Five-week intervention using reduced CHO (43% carbohydrate; 27% fat: SPEC) versus standard CHO (55% carbohydrate; 40% fat: STAN) eucaloric diet. Subjects were 28 obese African American females, aged 9–14 years. Dual energy X-ray absorptiometry and meal test were performed at baseline and five weeks. Results. Approximately 30% of girls had metabolic syndrome. Serum 25OHD increased in both groups at five weeks [STAN: 20.3 ± 1.1 to 22.4 ± 1.1 ( ) versus SPEC: to ( )]. The STAN group, increased 25OHD concentration over five weeks ( ), which was positively related to triglycerides ( ) and inversely associated with total cholesterol ( ) and LDL ( ). The SPEC group, had increase in 25OHD ( ), which was positively related to fasting insulin ( ) and insulin sensitivity while inversely associated with fasting glucose ( ). The contribution of vitamin D status to metabolic syndrome parameters differs according to macronutrient intake. Improvement in 25OHD may improve fasting glucose, insulin sensitivity, and LDL; however, macronutrient intake warrants consideration. 1. Introduction The steady rise in prevalence of pediatric obesity over the past three decades has been accompanied by accumulation of risk factors for metabolic syndrome (MetSyn) in childhood and adolescence. The occurrence of hypovitaminosis D (expressed as levels <20?ng/mL of circulating 25-hydroxy vitamin D (25OHD)) has been increasingly documented in the same population [1, 2]. Moreover, children/adolescents with hypovitaminosis D have been reported to experience greater instances of hypertension, hypertriglyceridemia, hyperglycemia, and low high-density lipoprotein cholesterol (HDL) [1, 3, 4]. Further, it has been proposed that elevated parathyroid hormone (PTH), consequential to chronic low vitamin D level, is mechanistically involved in the adverse perturbations of risk factors underlying MetSyn [5]. Given the emerging identification of vitamin D as an integral player in numerous metabolic pathways, it stands to reason that vitamin D status in the pediatric populace may play a role in the prevalence of metabolic disease risk factors [6, 7]. The relationship between 25OHD status and metabolic health is not equally distributed across groups. In particular, the relationship is more apparent among African American (AA) females, particularly those who are overweight/obese
Associations of C-Reactive Protein to Indices of Vascular Health and the Influence of Serum 25(OH)D Status in Healthy Adults
Ambika P. Ashraf,Gordon Fisher,Jessica Alvarez,Tanja Dudenbostel,David A. Calhoun,Alexander J. Szalai,Barbara A. Gower
Journal of Nutrition and Metabolism , 2012, DOI: 10.1155/2012/475975
Abstract: Elevated serum high-sensitivity C-reactive protein (hs-CRP) and low serum 25-hydroxyvitamin D [25(OH)D] are associated with increased cardiovascular disease (CVD) risk. Ethnic differences in serum hs-CRP and 25(OH)D concentrations and CVD are known. Objectives: to investigate the ethnic differences in hs-CRP concentrations, to assess the influence of 25(OH)D on these ethnic differences and to examine the influence of 25(OH)D on association between hs-CRP and cardiovascular health indices. Subjects: 62 healthy adults [26 African Americans (AA), 26 European Americans (EA), and 10 Hispanic Americans (HA)], ages 18–55 years. Serum hs-CRP and 25(OH)D as well as pulse wave velocity (PWV), augmentation index (AIx), and flow-mediated dilatation (FMD) were measured. hs-CRP was inversely associated with 25(OH)D (, ), and hs-CRP was positively associated with PWV (, ). The association of hs-CRP with PWV attenuated after adjustment for 25(OH)D (). hs-CRP was higher in AA compared to EA (); this differences was reduced by 32% after adjusting for serum 25(OH)D. Conclusion: eventhough the inverse association between serum 25(OH)D and CRP does not infer causality, lower serum 25(OH)D may increase risk for inflammation and endothelial dysfunction. The lower 25(OH)D in AA may predispose to greater inflammation and associated vascular dysfunction.
Associations of C-Reactive Protein to Indices of Vascular Health and the Influence of Serum 25(OH)D Status in Healthy Adults
Ambika P. Ashraf,Gordon Fisher,Jessica Alvarez,Tanja Dudenbostel,David A. Calhoun,Alexander J. Szalai,Barbara A. Gower
Journal of Nutrition and Metabolism , 2012, DOI: 10.1155/2012/475975
Abstract: Elevated serum high-sensitivity C-reactive protein (hs-CRP) and low serum 25-hydroxyvitamin D [25(OH)D] are associated with increased cardiovascular disease (CVD) risk. Ethnic differences in serum hs-CRP and 25(OH)D concentrations and CVD are known. Objectives: to investigate the ethnic differences in hs-CRP concentrations, to assess the influence of 25(OH)D on these ethnic differences and to examine the influence of 25(OH)D on association between hs-CRP and cardiovascular health indices. Subjects: 62 healthy adults [26 African Americans (AA), 26 European Americans (EA), and 10 Hispanic Americans (HA)], ages 18–55 years. Serum hs-CRP and 25(OH)D as well as pulse wave velocity (PWV), augmentation index (AIx), and flow-mediated dilatation (FMD) were measured. hs-CRP was inversely associated with 25(OH)D ( , ), and hs-CRP was positively associated with PWV ( , ). The association of hs-CRP with PWV attenuated after adjustment for 25(OH)D ( ). hs-CRP was higher in AA compared to EA ( ); this differences was reduced by 32% after adjusting for serum 25(OH)D. Conclusion: eventhough the inverse association between serum 25(OH)D and CRP does not infer causality, lower serum 25(OH)D may increase risk for inflammation and endothelial dysfunction. The lower 25(OH)D in AA may predispose to greater inflammation and associated vascular dysfunction. 1. Introduction Chronic inflammatory stress, endothelial dysfunction, and arterial stiffness are key underlying factors in the pathogenesis of atherosclerosis [1, 2]. C-reactive protein (CRP), an acute phase protein synthesized primarily in the liver, is an established biomarker of inflammation, is known to alter endothelial function via increased nitric oxide production [3] and its serum levels are positively associated with the development of cardiovascular disease (CVD) [4–6]. High-sensitivity C-reactive protein (hs-CRP) concentration is also associated with pulse wave velocity (PWV), the gold standard for assessing arterial stiffness, suggesting that inflammation is linked to arterial stiffness [7–9]. There is evidence that African Americans (AA) and Hispanic Americans (HA) have a greater risk of complications from CVD compared with European Americans (EA) [10, 11]. However to date, results vary as to whether or not inflammation differs between AA and EA. Khera et al. found higher hs-CRP concentrations among AA men and women between ages 30–65 years as compared to EA [12], whereas we have previously shown no differences in hs-CRP concentrations between AA and EA premenopausal women [13]. Additionally, AA have been shown
Role of Vitamin D in Insulin Secretion and Insulin Sensitivity for Glucose Homeostasis
Jessica A. Alvarez,Ambika Ashraf
International Journal of Endocrinology , 2010, DOI: 10.1155/2010/351385
Abstract: Vitamin D functions are not limited to skeletal health benefits and may extend to preservation of insulin secretion and insulin sensitivity. This review summarizes the literature related to potential vitamin D influences on glucose homeostasis and insulin sensitivity. Cross-sectional data provide some evidence that circulating 25-hydroxyvitamin D (25(OH)D) is inversely associated with insulin resistance, although direct measurements of insulin sensitivity are required for confirmation. Reported associations with insulin secretion, however, are contradictory. Available prospective studies support a protective influence of high 25(OH)D concentrations on type 2 diabetes mellitus risk. There is a general lack of consistency in vitamin D intervention outcomes on insulin secretion and sensitivity, likely due to differences in subject populations, length of interventions, and forms of vitamin D supplementation. Vitamin D receptor gene polymorphisms and vitamin D interactions with the insulin like growth factor system may further influence glucose homeostasis. The ambiguity of optimal vitamin D dosing regimens and optimal therapeutic concentrations of serum 25(OH)D limit available intervention studies. Future studies, including cross-sectional and prospective, should be performed in populations at high risk for both vitamin D deficiency and type 2 diabetes mellitus. Well-designed, placebo-controlled, randomized intervention studies are required to establish a true protective influence of vitamin D on glucose homeostasis. 1. Introduction Over the last decade, numerous nonskeletal disease associations have been reported with vitamin D deficiency, including type 2 diabetes mellitus (T2DM). Circulating 25-hydroxyvitamin D (25(OH)D) concentrations are considered an indicator of vitamin D status [1, 2]. Compared to healthy controls, subjects with T2DM have been observed to have significantly lower circulating 25(OH)D concentrations [3–5]. Perhaps not coincidently, both vitamin D deficiency and T2DM share the same risk factors, including African-American, Asian, or Hispanic ethnicity, increased adiposity, age, and physical inactivity (which may translate to decreased time spent outdoors or reduced sun exposure) [6, 7]. Seasonal variations in glucose and insulin concentrations have been reported [8], which may correlate with seasonal variations in 25(OH)D concentrations [9]. Although not within the scope of this review, vitamin D has likewise been implicated in the development of type 1 diabetes mellitus due to its modulation of the immune system [10]. T2DM is
Racial Disparities on Glycemic Control and Lipid Profiles in Children with Type 1 Diabetes
Ambika Ashraf, Yufeng Li, Frank Franklin, Kenneth McCormick and Elaine Moreland
Clinical Medicine Insights: Endocrinology and Diabetes , 2012,
Abstract: Objective: We assessed the racial (Black–White) differences in glycemic control, prevalence of abnormal lipid profiles and factors influencing temporal trends in children with type 1 diabetes (T1DM). Methods: This retrospective study was done in children with T1DM. The outcome measure was based on glycemic control and all lipid determinations which were stratified according to the published guidelines. Results: The study included 181 children; 76.2% Whites and 23.8% Blacks. The mean glycated hemoglobin (A1C) was higher in Blacks than in Whites (p < 0.0001). Blacks had elevated total cholesterol (TC) (p = 0.0013), lower TC/HDL ratio (p < 0.0001) and higher concentration of HDL ( <0.0001) when compared to Whites. The longitudinal analyses over a 5 year period showed changes in A1C significantly associated with changes in the lipid profiles. The lipid profiles in Blacks were more altered by the trend in A1C with changes in the TC (p = 0.0079), non-HDL (p < 0.0001) and HDL (p < 0.0001). Conclusions: Black children with T1DM have poorer glycemic control. However they retained excellent levels of HDL when compared to Whites.
Racial Disparities on Glycemic Control and Lipid Profiles in Children with Type 1 Diabetes
Ambika Ashraf,Yufeng Li,Frank Franklin,Kenneth McCormick
Clinical Medicine : Endocrinology and Diabetes , 2009,
Abstract: Objective: We assessed the racial (Black–White) differences in glycemic control, prevalence of abnormal lipid profiles and factors influencing temporal trends in children with type 1 diabetes (T1DM).Methods: This retrospective study was done in children with T1DM. The outcome measure was based on glycemic control and all lipid determinations which were stratified according to the published guidelines.Results: The study included 181 children; 76.2% Whites and 23.8% Blacks. The mean glycated hemoglobin (A1C) was higher in Blacks than in Whites (p < 0.0001). Blacks had elevated total cholesterol (TC) (p = 0.0013), lower TC/HDL ratio (p < 0.0001) and higher concentration of HDL ( <0.0001) when compared to Whites. The longitudinal analyses over a 5 year period showed changes in A1C significantly associated with changes in the lipid profiles. The lipid profiles in Blacks were more altered by the trend in A1C with changes in the TC (p = 0.0079), non-HDL (p < 0.0001) and HDL (p < 0.0001).Conclusions: Black children with T1DM have poorer glycemic control. However they retained excellent levels of HDL when compared to Whites.
Resonance phenomena in discrete systems with bichromatic input signal
K. P. Harikrishnan,G. Ambika
Physics , 2007, DOI: 10.1140/epjb/e2008-00083-3
Abstract: We undertake a detailed numerical study of the twin phenomena of stochastic and vibrational resonance in a discrete model system in the presence of bichromatic input signal. A two parameter cubic map is used as the model that combines the features of both bistable and threshold settings. Our analysis brings out several interesting results, such as, the existence of a cross over behaviour from vibrational to stochastic resonance and the possibility of using stochastic resonance as a filter for the selective detection/transmission of the component frequencies in a composite signal. The study also reveals a fundamental difference between the bistable and threshold mechanisms with respect to amplification of a multi signal input.
Stochastic resonance as a filter for signal detection from multisignal inputs
K P Harikrishnan,G Ambika
Physics , 2006,
Abstract: We undertake a detailed numerical study of the phenomenon of stochastic resonance with multisignal inputs. A bistable cubic map is used as the model and we show that it combines the features of a bistable system and a threshold system. A study of stochastic resonance in these two setups reveal some fundamental differences between the two mechanisms with respect to amplification of a composite input signal. As a practically relevant result, we show that the phenomenon of stochastic resonance can be used as a filter for the detection/transmission of the component frequencies in a composite signal.
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