Plasma Retinol Research Articles

1986-P: Plasma Retinol Binding Protein 4 and Adipsin Levels Were Not Altered after Gastric Sleeve Surgery in Adult Male Population

Background: Bariatric or weight loss surgery provides the most substantial and sustainable weight loss in individuals with obesity. Caloric restriction and malabsorption are not the only mechanisms by which bariatric surgery reduces body weight and improves glycemic control. Alterations in the secretion and activity of hormones are also the contributory mechanisms in bariatric surgery. We evaluated the levels of retinol binding protein 4 (RBP4) and adipsin after gastric sleeve surgery and their relationship with insulin and lipid parameters. Method: Thirty-three obese (BMI > 38.3) healthy male subjects age ranged from 25 to 50 years were selected for this study. Plasma levels of RBP4 and adipsin were analyzed before and six months after gastric sleeve surgery by ELISA, along with plasma glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and lipid profile. Results: Circulating RBP4 was not significantly changed by bariatric surgery (4382.85±7.03 ng before, and 4393.28±5.769 ng after surgery, P= 0.842), neither did adipsin (2949.68±8.16 pg before, and 2917.90±7.295 pg after surgery, P=0.535). As expected, there was a reduction in BMI, insulin levels and HOMA-IR after six months of surgery. Lipid profile analysis revealed that cholesterol, high density lipoproteins (HDL), and low density lipoproteins (LDL) levels were increased after surgery (4.26±0.027 to 5.12±0.026 mmol/L and 0.90±0.007 to 1.55±0.011 mmol/L and 2.62±0.02 to 2.98±0.022 mmol/L, P<0.001) respectively. However, there was no correlation between RBP4, adipsin and insulin and lipid parameters. Conclusions: Our findings do not suggest a role for RBP4 and adipsin in the improvement of insulin sensitivity in obese male population after gastric sleeve surgery. Moreover, there was no correlation between their plasma levels and either BMI, glucose, insulin, or lipid profiles. Disclosure S. Alshubrami: None. M. Iqbal: None. A. Alfadda: None. K. Alregaiey: None. Funding King Abdulaziz City for Science and Technology (1-17-03-001-0026)

The Accuracy of Dried Blood Spots Compared to Plasma or Serum Retinol for the Diagnosis of Vitamin A Deficiency: A DTA Systematic Review and Meta-Analysis

Abstract Objectives Dried blood spots (DBS) do not require a cold chain, making them easier to store and transport compared to serum or plasma samples in resource-limited settings. Our objective was to determine the accuracy of DBS compared to serum or plasma retinol for assessing vitamin A status in individuals and populations. Methods A systematic review of diagnostic test accuracy (DTA) was performed using standard Cochrane Methods for Screening and Diagnostic Tests. All human studies were included if they determined retinol in DBS (index test) and compared results to retinol determined in either plasma or serum samples (reference standard). Index and reference methods could use either capillary or venous blood with retinol quantified by HPLC. We used the WHO threshold of 0.70 μmol/L to define low retinol concentrations. Meta-analysis determined summary estimates of sensitivity and specificity using the bivariate model, which models logit transformed sensitivities and specificities as a bivariate normal distribution including a parameter for the negative correlation between sensitivity and specificity. Rstudio (Version 1.1.456, RStudio, Inc. Boston, MA) was used for analysis. Results Our search (conducted April 10, 2019) identified 9021 records, and 285 studies were assessed in full-text for inclusion; 6 publications reported 8 studies comprising 397 participants, 50 of which had low serum retinol by the reference method. The use of DBS to determine a low retinol level had summary estimates (95% CIs) for sensitivity of 86.7% (71.4 to 94.5) and specificity of 99.5% (89.7 to 100.0). Conclusions Use of DBS to determine low retinol has been shown to have good sensitivity and high specificity compared to serum or plasma. Use of DBS can reduce the need for centrifugation and cold chain for storage and transport. The mixed use of capillary and venous blood in both index and reference methods merits further investigation for the determination of retinol in DBS. Funding Sources None declared.

Plasma Untargeted Metabolomic Profile Associated with Vitamin A Status in Pregnant Women in Rural Bangladesh

Abstract Objectives Vitamin A status during pregnancy is important for visual health, immune function and fetal growth and development. However, little is known about how vitamin A may affect systemic metabolic function of undernourished pregnant women. The objective of this study is to characterize metabolic signatures and pathways associated with vitamin A status in pregnant women. Methods This study was nested into JiVitA-3, a community-based antenatal multiple micronutrient vs. iron-folic acid supplementation trial in rural Bangladesh. In plasma samples of 150 women at ∼32 weeks of gestation, retinol had been measured by HPLC and relative abundances of metabolites were measured by UPLC Q-Exactive HF-X mass spectrometer. Univariate linear regression was used to determine metabolites associated with plasma retinol. Multiple testing was corrected using a false discovery rate threshold of 5%. Results Among 2985 peak features included in data analysis, 97 known metabolites were positively or negatively associated with plasma retinol concentrations. Among the top 11 positive correlates, seven metabolites are tryptophan or its metabolic catabolites including 5-methoxy tryptophan, tryptamine, 5-methoxytryptamine, N-formylkynureine, indole, 2-indolecarboxylic acid, and 3-methylene-indolenine (r = 0.32∼0.42, p-value < 8 × 10−5). Pathway analysis demonstrated that metabolic pathways of tryptophan, nicotinamide (vitamin B3), lysine, arginine and proline were significantly enriched (gamma p-value < 0.05). Conclusions An untargeted plasma metabolomics platform revealed associations of microbial catabolites of tryptophan and other amino acids with vitamin A status of undernourished pregnant women. These metabolites have been implicated in activation of intestinal immune cells and anti-inflammatory and anti-oxidative functions. The results suggest novel mechanisms by which vitamin A may influence immune system and systemic homeostasis, prompting a need for confirmatory studies. Funding Sources The JiVitA-3 trial and micronutrient status assessments were funded by the Bill and Melinda Gates Foundation (West, PI). Metabolomics analysis was funded from the NIH Common Fund Metabolomics Program (Sumner, PI).

Reduced Plasma Lipid Mediators Are Directly Associated with Low Vitamin A Status in Women from Western Samar, Philippines

Abstract Objectives Vitamin A (VA) is an essential micronutrient that plays a key role in many biological processes, including growth, vision, immunity and reproduction. While evidence has been established to support these mechanisms, new studies suggest there may be more signaling compounds that are impacted by VA status. Lipid mediators, such as oxylipins and lysophospholipids, are signaling compounds that, in response to biological stimuli, exhibit regulatory effects on inflammation, immune function, vascular tone, and other systems. The objective was to investigate differences in lipid mediators associated with VA status. Methods In this cross-sectional study, blood samples from women in Western Samar, Philippines, were selected based on plasma retinol concentration indicating adequate (n = 5) or low (n = 5) VA status (retinol < 0.7 μmol/L). Retinol was measured using an Agilent 1200 HPLC-DAD. Oxylipin, endocannabinoid, bile acid, and lipidomics assays were analyzed on a Waters Acquity UPLC and detected using multiple reaction monitoring on a Sciex 4000 QTRAP. Data were adjusted for covariates related to the acute phase response, age, and BMI. Results Twenty-four lipid mediators were lower in the low VA status group (P < 0.05). These lipid mediators included the arachidonic acid-derived oxylipins’ lipoxin A4 and 6-trans-LTB4 formed via lipoxygenases (LOX), as well as the cyclooxygenase (COX) product PGD2. Several LOX and soluble epoxide hydrolase (sEH) oxylipins produced from eicosapentaenoic acid and the acylethanolamides LEA and PEA were lower (P < 0.05) in individuals with low plasma retinol levels. Numerous phospholipids and sphingolipids were also lower (P < 0.05) with decreased VA status, including two lysophosphatidylcholines, three lysophosphatidylethanolamines, two phosphatidylcholines, and two sphingomyelins. Conclusions In this exploratory study, VA status was directly associated with lipid mediator concentrations. Future studies testing the biological impact of lipid mediator changes with varying levels of VA status are necessary. Funding Sources NIH U24 DK097154, USDA Intramural Project 2032–51,530-022–00D, NIH T32-GM008799, Cal Poly CAFES SURP.

Validation of a Method for Estimating Vitamin A Absorption Efficiency Based on Compartmental Analysis of Post-Prandial Plasma Retinyl Ester Kinetics

Abstract Objectives Because good methods are not available to estimate vitamin A (VA) absorption, we evaluated an approach based on modeling retinyl ester response to an oral VA dose. Methods We generated data for 12 theoretical subjects, assigning values for VA absorption, stores, and kinetic parameters; we used WinSAAM (Simulation, Analysis and Modeling software) to simulate data (without and with 5% average error) for plasma chylomicron retinyl esters (RE) and retinol versus time (30 min to 8 h or 56 d, respectively) after ingestion of labeled VA; next we fit data to a previously-published 9-component model for VA metabolism to obtain “known” values for VA absorption. Then RE data only were modeled for each subject using a robust (n = 16 times) vs truncated sampling schedule (n = 10) and model-predicted absorptions were compared to known values. Areas under the plasma RE response curves (AUCs) were also calculated and compared to known absorption values. Results Known values for VA absorption based on modeling all data with error ranged from 54 – 92% (mean, 72%), VA stores from 160 – 1775 μmol, and chylomicron t1/2 from 6 – 12 min. Using the full sampling scheme for RE, the ratio of model-predicted to known absorption ranged from 0.927 – 1.06 (mean, 0.997); using the truncated scheme, the ratio was 0.814 – 1.13 (mean, 0.973). AUCs were not significantly correlated with known values for VA absorption (R2 = 0.112; P > 0.05), presumably because absorption and chylomicron catabolism are occurring simultaneously. Conclusions By modeling chylomicron RE tracer data after ingestion of labeled VA, absorption efficiency was estimated accurately using error-free data; using data with 5% error, estimates were within 10% of known values (full sampling) or within 20% (truncated). If subjects, after an overnight fast, consume a breakfast containing some fat and a known amount of VA, then no tracer is required to estimate VA absorption using this modeling approach. By incorporating a population-based design, the method could be used in children. Funding Sources Supported by Bill & Melinda Gates Foundation (Project Number OPP1115464) and HarvestPlus (BH183438).

A Novel LC-MS/MS Method for Improving Long-Term Stability of Retinol in Dried Blood Spots and Quantification of Its Levels

Abstract Objectives To establish an accurate and reliable method for stabilizing vitamin A (retinol) in Dried blood spots (DBS), quantifying and comparing DBS retinol concentrations with their equivalent plasma retinol levels. Methods Antioxidants pretreated on paper combined with vacuum treatment were used to increase retinol stability on DBS. A surrogate matrix of whole blood prepared using mixture of human erythrocytes and 2% BSA in PBS was firstly used in DBS retinol determination based on the fact that retinol is excluded from erythrocytes. Results DBS retinol was stable during 120 min of air drying and 30 days of room-temperature storage. The method was linear in the concentration range of 0.04–300 μg/mL. Accuracy was calibrated using two National Institute of Standards and Technology (NIST) calibrants generated serum at concentrations of 0.1962 and 0.3948 g/mL, relative errors (RE% values) of 0.07% and 4.95% were found, respectively. Both the between-run (n = 5) and within-run (n = 6) precision (relative standard deviations, RSD%) were below 8.42%. The spiked recoveries at 3 concentrations ranged from 86.48% to 98.13%. A reliable calibration model was first developed to convert DBS retinol concentration to the equivalent plasma retinol concentration. Conclusions The validated method can be applied to the nutritional assessment of vitamin A, using the established calibration model, DBS retinol can compare with clinical reference ranges and with studies using serum or plasma samples. Funding Sources The National Key Research and Development Program of China (2018YFC1002503); The National Natural Science Foundation of China (Grant No. 81,400,848, 81,701,441); The CAMS Initiative for Innovative Medicine (2016-I2M-1–008); The Beijing municipal program of medical research (Grant No. 2016–04); The National Key Research and Development Program of China (No. 2016YFC1306204).

Dynamics of vitamin A uptake, storage, and utilization in vocal fold mucosa

ObjectiveExtrahepatic vitamin A is housed within organ-specific stellate cells that support local tissue function. These cells have been reported in the vocal fold mucosa (VFM) of the larynx; however, it is unknown how vitamin A reaches and is disseminated among VFM target cells, how VFM storage and utilization vary as a function of total body stores, and how these parameters change in the context of pathology. Therefore, in this study, we investigated fundamental VFM vitamin A uptake and metabolism. MethodsUsing cadaveric tissue and serum from human donors representing the full continuum of clinical vitamin A status, we established a concentration range and analyzed the impact of biologic and clinical covariates on VFM vitamin A. We additionally conducted immunodetection of vitamin A-associated markers and pharmacokinetic profiling of orally dosed α-retinyl ester (a chylomicron tracer) in rats. ResultsSerum vitamin A was a significant predictor of human VFM concentrations, suggesting that VFM stores may be rapidly metabolized in situ and replenished from the circulatory pool. On a vitamin A-sufficient background, dosed α-vitamin A was detected in rat VFM in both ester and alcohol forms, showing that, in addition to plasma retinol and local stellate cell stores, VFM can access and process postprandial retinyl esters from circulating chylomicra. Both α forms were rapidly depleted, confirming the high metabolic demand for vitamin A within VFM. ConclusionThis thorough physiological analysis validates VFM as an extrahepatic vitamin A repository and characterizes its unique uptake, storage, and utilization phenotype.

Association between plasma retinol levels and the risk of all-cause mortality in general hypertensive patients: A nested case-control study.

To evaluate the association between plasma retinol levels with all-cause mortality and investigate the possible effect modifiers in general hypertensive patients with no previous cardiovascular disease (CVD). This case-control study was nested in the China Stroke Primary Prevention Trial (CSPPT), a randomized, double-blind, controlled trial conducted in 32 communities in Anhui and Jiangsu provinces in China. The current study included 617 cases of all-cause mortality and 617 controls matched on age (≤1year), sex, treatment group, and study site. All-cause mortality was the main outcome in this analysis, which included death due to any reason. The median follow-up duration was 4.5years. Overall, there was a U-shaped relation of plasma retinol with all-cause mortality. In the threshold effect analysis, the risk of all-cause mortality significantly decreased with the increase in plasma retinol (per 10μg/dL increments: OR, 0.73; 95% CI: 0.61-0.87) in participants with plasma retinol <58.3μg/dL and increased with the increase in plasma retinol (per 10μg/dL increments: OR, 1.08; 95% CI: 1.01-1.16) in those with plasma retinol ≥58.3μg/L. In participants with plasma retinol <58.3μg/dL, a stronger inverse association was observed in those with higher time-averaged SBP (≥140 vs <140mmHg; P-interaction=.034), or higher vitamin E levels (≥11.5 [quartile 4]; vs <11.5μg/mL; P-interaction=.013). The present study demonstrated that there was a U-shaped relationship of plasma retinol levels with the risk of all-cause mortality in general hypertensive patients, with a turning point around 58.3μg/dL.

Distribution of injected fat-soluble vitamins in plasma and tissues of nursery pigs.

ObjectiveThe objective of this experiment was to investigate the effects of fat-soluble vitamin injection on plasma and tissue vitamin status in nursery pigs.MethodsA total of 16 pigs (initial body weight: 7.15±1.1 kg) were allotted to 2 treatments at d 7 post-weaning. Pigs were fed a corn-soybean meal-based basal diet with no supplemental vitamin A and i.m. injected with 300,000 IU of retinyl palmitate, 900 IU of d-α-tocopherol and 30,000 IU of vitamin D3 with control pigs having no vitamin injection. Blood (d 0, 3, 7, and 14 post-injection) and tissue samples (liver, brain, heart, lung, and muscle; d 7 and 14 post-injection) were collected from pigs. Retinyl palmitate, retinol, and α-tocopherol concentrations were analyzed in plasma and tissues, while plasma was assayed for 25-hydroxycholecalciferol (25-OHD3).ResultsPlasma retinol and 25-OHD3 concentrations increased by the vitamin injection from d 3 to 14 post-injection (p<0.05) whereas plasma retinyl palmitate was detected only in the vitamin treatment at d 3 and 7 post-injection (115.51 and 4.97 μg/mL, respectively). Liver retinol, retinyl palmitate, and retinol+retinyl palmitate concentrations increased by retinyl palmitate injection at d 7 and 14 post-injection (p<0.05) whereas those were not detected in the other tissues. The d-α-tocopherol injection increased α-tocopherol concentrations in plasma at d 3 and 7 post-injection (p<0.05) and in liver, heart (p<0.10), and muscle (p<0.05) at d 7 post-injection.ConclusionFat-soluble vitamin injection increased plasma status of α-tocopherol, retinol, retinyl palmitate and 25-OHD3. As plasma levels decreased post-injection, vitamin A level in liver and vitamin E level in muscle, heart and liver increased. The α-tocopherol found in plasma after injection was distributed to various tissues but retinyl palmitate only to the liver.

Plasma carotenoids, tocopherols and retinol - Association with age in the Berlin Aging Study II

Regular consumption of fruits and vegetables, which is related to high plasma levels of lipid-soluble micronutrients such as carotenoids and tocopherols, is linked to lower incidences of various age-related diseases. Differences in lipid-soluble micronutrient blood concentrations seem to be associated with age. Our retrospective analysis included men and women aged 22–37 and 60–85 years from the Berlin Aging Study II. Participants with simultaneously available plasma samples and dietary data were included (n = 1973). Differences between young and old groups were found for plasma lycopene, α-carotene, α-tocopherol, β-cryptoxanthin (only in women), and γ-tocopherol (only in men). β-Carotene, retinol and lutein/zeaxanthin did not differ between young and old participants regardless of the sex. We found significant associations for lycopene, α-carotene (both inverse), α-tocopherol, γ-tocopherol, and β-carotene (all positive) with age. Adjusting for BMI, smoking status, season, cholesterol and dietary intake confirmed these associations, except for β-carotene. These micronutrients are important antioxidants and associated with lower incidence of age-related diseases, therefore it is important to understand the underlying mechanisms in order to implement dietary strategies for the prevention of age-related diseases. To explain the lower lycopene and α-carotene concentration in older subjects, bioavailability studies in older participants are necessary.

Use of Model-Based Compartmental Analysis and a Super-Child Design to Study Whole-Body Retinol Kinetics and Vitamin A Total Body Stores in Children from 3 Lower-Income Countries

ABSTRACTBackgroundModel-based compartmental analysis has been used to describe and quantify whole-body vitamin A metabolism and estimate total body stores (TBS) in animals and humans.ObjectivesWe applied compartmental modeling and a super-child design to estimate retinol kinetic parameters and TBS for young children in Bangladesh, Guatemala, and the Philippines.MethodsChildren ingested [13C10]retinyl acetate and 1 or 2 blood samples were collected from each child from 6 h to 28 d after dosing. Temporal data for fraction of dose in plasma [13C10]retinol were modeled using WinSAAM software and a 6-component model with vitamin A intake included as weighted data.ResultsModel-predicted TBS was 198, 533, and 1062 μmol for the Bangladeshi (age, 9–17 mo), Filipino (12–18 mo), and Guatemalan children (35–65 mo). Retinol kinetics were similar for Filipino and Guatemalan groups and generally faster for Bangladeshi children, although fractional transfer of plasma retinol to a larger exchangeable storage pool was the same for the 3 groups. Recycling to plasma from that pool was ∼2.5 times faster in the Bangladeshi children compared with the other groups and the recycling number was 2–3 times greater. Differences in kinetics between groups are likely related to differences in vitamin A stores and intakes (geometric means: 352, 727, and 764 μg retinol activity equivalents/d for the Bangladeshi, Filipino, and Guatemalan children, respectively).ConclusionsBy collecting 1 or 2 blood samples from each child to generate a composite plasma tracer data set with a minimum of 5 children/time, group TBS and retinol kinetics can be estimated in children by compartmental analysis; inclusion of vitamin A intake data increases confidence in model predictions. The super-child modeling approach is an effective technique for comparing vitamin A status among children from different populations. These trials were registered at www.clinicaltrials.gov as NCT03000543 (Bangladesh), NCT03345147 (Guatemala), and NCT03030339 (Philippines).

СОДЕРЖАНИЕ РЕТИНОЛА И α-ТОКОФЕРОЛА ПРИ ЭКСПЕРИМЕНТАЛЬНОМ ФИБРОЗЕ ПЕЧЕНИ У КРЫС

Background. The content of retinol and α-tocopherol in the human body affects the development and progression of chronic liver diseases and is associated with the functioning of perisinusoidal lipocytes (HSC) and the state of biological membranes. Objective – to evaluate the content of retinol and α-tocopherol in blood plasma and liver tissue in the dynamics of experimental liver fbrosis in rats. Material and methods. Modeling of liver fbrosis / cirrhosis was carried out on sexually mature male rats by intraperitoneal administration of thioacetamide (TAA) solution at a dose of 200 mg / kg every other day for 4 and 12 weeks. The control group of animals received an equal volume of saline. The concentration of α-tocopherol and retinol was determined by S.L. Taylor’s method. Results. In rat liver preparations, 4 weeks after administration of TAA solution to animals, signs of FII-III stage of fbrosis were observed. According to electron microscopy, HSCs were in a transitional state and acquired a more elongated shape; the number of lipid inclusions in their cytoplasm decreased. The administration of TAA for 12 weeks led to the formation of liver cirrhosis in rats, with characteristic macro- and microscopic changes. On light microscopy, the number of HSCs decreased in rat liver preparations 3 months after administration of TAA; activated HSCs were encountered, which acquired an elongated shape and lost lipid inclusions. The content of retinol in the 2nd group of animals (with liver fbrosis stage II-III) was 2.2 times higher than in the control group, and 1.8 times higher than in the 3rd group with liver cirrhosis (p &lt; 0.05). The content of retinol in the liver tissue after 4 weeks of TAA administration decreased by 11.7%, after 12 weeks - by 1.5 times. The level of α-tocopherol in the liver at the stage of fbrosis FII-III decreased by 21% compared with the control group, at the stage of cirrhosis - by 2 times. Conclusion. The use of thioacetamide in rats for 1 and 3 months leads to the development of liver fbrosis and cirrhosis. A decrease in the content of retinol and α-tocopherol in the liver occurs with the progression of liver fbrosis /cirrhosis. The high content of retinol and α-tocopherol in plasma at the stage of liver fbrosis FII-III is due to degranulation (activation) of HSC.

Impact of Gastric Sleeve Surgery on Plasma Retinol Binding Protein 4 and Adipsin Levels in Healthy Male Population.

Objectives:Bariatric surgery provides most substantial and sustainable weight loss measures in individuals with obesity. Caloric restriction is not only intervention, changes in hormonal secretions are also leading contributory mechanisms to reduce body weight and improve the glycaemic control. The aim of this study was to evaluate the impact of gastric sleeve surgery on plasma retinol binding protein 4 (RBP4) and adipsin levels among Saudi male obese population.Methods:This prospective study was conducted in the Departments of Physiology and Surgery, College of Medicine, King Saud University. Thirty-three obese (BMI>38.3) male patients age ranged from 25 to 50 years were recruited. RBP4 and adipsin levels were analyzed before and 6-12 months after gastric sleeve surgery by ELISA along with plasma glucose, insulin, HOMA-IR and lipid profile.Results:Circulating RBP4 levels were not significantly changed by bariatric surgery (4382.85±40.35 ng before, and 4393.28±33.13 ng after surgery, p=0.842), neither did adipsin (2949.68±46.86 pg before, and 2917.90±41.90 pg after surgery, p=0.535). Segregation of study participants into two age groups, 25-35 and 35-50 years of age, revealed that before surgery older age group (35-50) had higher RBP4 levels compared to younger group (25-35) (p=0.016). However, after surgery RBP4 levels were decreased in older group but not to a significant level (p=0.174). In younger age group after surgery, there was a near significant increase in RBP4 levels (p=0.052). There were no significant changes in RBP4 levels in both age groups after surgery (p=0.461). For adipsin, there were no significant differences before and after surgery in both age groups. Insulin, BMI and HOMA-IR index were decreased after surgery, however there was no correlation with RBP4 and adipsin levels.Conclusions:The present study findings do not suggest a role for RBP4 and adipsin in the improvement of insulin sensitivity in Saudi male obese population after gastric sleeve surgery. However, a decrease in RBP4 levels in older individuals after surgery needs further investigations to understand its effect on weight and glycemic control.

Why Do Children in Slums Suffer from Anemia, Iron, Zinc, and Vitamin A Deficiency? Results from a Birth Cohort Study in Dhaka.

Considering the high burden of micronutrient deficiencies in Bangladeshi children, this analysis aimed to identify the factors associated with micronutrient deficiencies and association of plasma micronutrient concentration trajectories from 7 to 24 months with the concentrations at 60 months of age. Plasma samples were collected at 7, 15, 24, and 60 months of age, and hemoglobin, ferritin, zinc, and retinol concentrations of 155, 153, 154, and 155 children were measured, respectively. A generalized estimating equation was used to identify the factors associated with micronutrient deficiencies, while latent class growth modeling identified the trajectories of plasma micronutrients from 7 to 24 months and its association with the concentrations of micronutrients at 60 months was examined using multiple linear regression modeling. Early (AOR = 2.21, p < 0.05) and late convalescence (AOR = 1.65, p < 0.05) stage of an infection, low ferritin (AOR = 3.04, p < 0.05), and low retinol (AOR = 2.07, p < 0.05) were associated with increased anemia prevalence. Wasting at enrollment was associated with zinc deficiency (AOR = 1.8, p < 0.05) and birth weight was associated with ferritin deficiency (AOR = 0.58, p < 0.05). Treatment of drinking water was found protective against vitamin A deficiency (AOR = 0.57, p < 0.05). Higher trajectories for ferritin and retinol during 7–24 months were positively associated with plasma ferritin (β = 13.72, p < 0.05) and plasma retinol (β = 3.99, p < 0.05) at 60 months.

Improving long-term stability of retinol in dried blood spots and quantification of its levels via a novel LC-MS/MS method.

Vitamin A deficiency (VAD) is a major micronutrient deficiency in children. Although plasma and serum retinol levels are proposed as the key indicators of VAD, collecting and transporting plasma and serum are difficult and inconvenient in field studies. Dried blood spot (DBS) retinol has been used as an alternative to plasma retinol in several epidemiological and clinical studies. A limitation of methods that use DBS retinol is the instability and apparent loss of retinol in DBSs. Therefore, an accurate, reliable method for stabilizing retinol in DBSs and quantifying and comparing DBS retinol concentrations with equivalent plasma retinol levels is required. In this study, antioxidants on paper combined with vacuum treatment were found to greatly increase the stability of DBS retinol during 120min of air drying and 30days of room-temperature storage. A surrogate matrix of whole blood prepared using a mixture of human erythrocytes and 2% BSA in PBS was firstly used in DBS retinol determination based on the fact that retinol is excluded from erythrocytes. The method was linear in the concentration range of 0.04-300μg/mL. Both the between-run (n = 5) and within-run (n = 6) precision (relative standard deviations, RSD%) were below 8.42%. The spiked recoveries at 3 concentrations ranged from 86.48 to 98.13%. The internal standard (IS)-normalized matrix factor (MF) was 99.72% with a RSD% of 10.50% (n = 3). The accuracy was calibrated using two National Institute of Standards and Technology (NIST) serum-generated calibrants at concentrations of 0.1962 and 0.3948g/mL, and relative errors (RE% values) of 0.07% and 4.95% were found, respectively. A simple calibration model was first developed to convert DBS retinol concentration to the equivalent plasma retinol concentration, thereby enabling comparisons with clinical reference ranges and with studies using serum or plasma samples. Graphical abstract.

Addition of Vitamin A Intake Data during Compartmental Modeling of Retinol Kinetics in Theoretical Humans Leads to Accurate Prediction of Vitamin A Total Body Stores and Kinetic Parameters in Studies of Reasonable Duration

BackgroundMathematical modeling of theoretical data has been used to validate experimental protocols and methods in several fields. ObjectiveWe hypothesized that adding dietary vitamin A intake data as an input during compartmental modeling of retinol kinetics would lead to accurate prediction of vitamin A total body stores (TBS) at 2 specified study lengths and would reduce study duration required to accurately define the system. MethodsWe generated reference values for state variables (including TBS and intake) and kinetic parameters for 12 theoretical individuals (4 each of children, younger adults, and older adults) based on modeling plasma retinol tracer data for 365 d. We compared TBS predictions using data to 28 d (children) or 56 d (adults) without and with intake included in the model to reference values for each subject. Then, by truncating data sets from 365 d, we determined the shortest study duration required to accurately define the system without and with inclusion of vitamin A intake. ResultsReference values for TBS ranged from 30 to 3023 µmol. Study durations of 28 and 56 d were sufficient to accurately predict TBS for 6 of the 12 subjects without intake; adding intake resulted in accurate predictions of TBS for all individuals. When intake was not included as a modeling input, durations of 35–310 d were required to define the system; inclusion of intake data substantially reduced the time required to 10–42 d. ConclusionsInclusion of vitamin A intake as additional data input when modeling vitamin A kinetics allows investigators to accurately predict TBS and define the vitamin A system in studies of reasonable length (4 wk in children and 8 wk in adults). Because it is generally possible to obtain estimates/measures of intake, including such data increases confidence in model predictions while also making studies more feasible.

Plasma Levels of Retinol Binding Protein 4 Relate to Large VLDL and Small LDL Particles in Subjects with and without Type 2 Diabetes.

Background: Retinol binding protein 4 (RBP4) carries retinol in plasma, but is also considered an adipokine, as it is implicated in insulin resistance in mice. Plasma RBP4 correlates with total cholesterol, low density lipoprotein (LDL)-cholesterol and triglycerides, and may confer increased cardiovascular risk. However, controversy exists about circulating RPB4 levels in type 2 diabetes mellitus (T2DM) and obesity. Here, we analyzed the relationships of RBP4 and retinol with lipoprotein subfractions in subjects with and without T2DM. Methods: Fasting plasma RBP4 (enzyme-linked immunosorbent assay) and retinol (high performance liquid chromatography) were assayed in 41 T2DM subjects and 37 non-diabetic subjects. Lipoprotein subfractions (NMR spectroscopy) were measured in 36 T2DM subjects and 27 non-diabetic subjects. Physical interaction of RBP4 with lipoproteins was assessed by fast protein liquid chromatography (FPLC). Results: Plasma RBP4 and retinol were strongly correlated (r = 0.881, p < 0.001). RBP4, retinol and the RBP4/retinol ratio were not different between T2DM and non-diabetic subjects (all p > 0.12), and were unrelated to body mass index. Notably, RBP4 and retinol were elevated in subjects with metabolic syndrome (p < 0.05), which was attributable to an association with elevated triglycerides (p = 0.013). Large VLDL, total LDL and small LDL were increased in T2DM subjects (p = 0.035 to 0.003). Taking all subjects together, RBP4 correlated with total cholesterol, non-HDL cholesterol, LDL cholesterol, triglycerides and apolipoprotein B in univariate analysis (p < 0.001 for each). Age-, sex- and diabetes status-adjusted multivariable linear regression analysis revealed that RBP4 was independently associated with large VLDL (β = 0.444, p = 0.005) and small LDL particles (β = 0.539, p < 0.001). Its relationship with large VLDL remained after further adjustment for retinol. RBP4 did not co-elute with VLDL nor LDL particles in FPLC analyses. Conclusions: Plasma RBP4 levels are related to but do not physically interact with large VLDL and small LDL particles. Elevated RBP4 may contribute to a proatherogenic plasma lipoprotein profile.

A308 Changes in Adipocyte (Ad) Retinol Metabolism May be Associated with Reduced Adipose Tissue Regulatory T Cells (AT-Tregs) after Bariatric Surgery

Adipocytes are a storage site for retinol and function as antigen presenting cells (APCs) to stimulate AT-Tregs, which are key determinants of insulin sensitivity. While AT-Tregs are reduced in obesity, we unexpectedly found AT-Tregs decreased after bariatric surgery (BS). Given retinol’s role in Treg differentiation, we hypothesize that post-operative vitamin A deficiency contributes to this reduction. We determined changes in Ad retinol-associated (RA) gene expression after BS and their association with plasma retinol and APC genes.

Evaluation of hematological and plasma biochemical parameters in green sea turtle (Chelonia mydas Linnaeus, 1758) from nesting colonies of the northern coast the Sea of Oman

The green turtle (Chelonia mydas) has been a species of global concern for decades. As an attempt to study health status of nesting green turtles, Blood biochemistry and hematological values were obtained from 18 clinically normal, nesting female green sea turtles on the northern coast of the sea of Oman. Mean curved carapace length (CCL) was 111 ± 4 cm with a range of 103—122 cm. Barnacles were recorded on three turtles. No fibropapillomas were observed on any of the 18 turtle.The mean PCV was 0.41 (proportion of 1) with a range of 0.30–0.58. No basophils or hemoparasites were detected in any of the 18 turtles tested. All biochemistry and hematological values of green sea turtles were within published reference ranges of healthy sea turtle population. No statistically significant differences were noted between the two anticoagulants for Plasma biochemistry values. Plasma alpha–tocopherol concentrations in the 18 turtles tested was 7.8 ± 2.8 g/ml with a range of 0.5—11.8 g/ml. Plasma retinol was evaluated in 18 turtles and the concentration was 0.4 ±0.1 g/ml with a range of 0.2—0.6 g/ml. The present study provides baseline data of the green sea turtle characterized by biological and nonbiological factors, which may provide the basis for future studies.

Combined consumption of a single high-dose vitamin A supplement with provision of vitamin A fortified oil to households maintains adequate milk retinol concentrations for 6 months in lactating Moroccan women.

In Morocco, postpartum women systematically receive a single, high dose of vitamin A (VA; 200 000 IU) within the first month of giving birth and vegetable oil is fortified to increase the VA intake. The efficacy of this combined approach of supplementation and fortification for increasing maternal VA status during lactation is not known. The purpose of the study is to evaluate the effect of postpartum high dose VA supplementation and provision of VA fortified oil for household consumption on plasma and milk retinol concentrations of lactating Moroccan women during the first 6 months after giving birth. Postpartum women aged 19-40 years received a VA supplement and thereafter were randomly assigned to one of two groups to receive weekly vitamin A fortified oil (FO) or non-fortified oil (NFO) for 6 months. Serum retinol concentration was higher in the FO group than in the NFO group at 6 months after giving birth (p < 0.0001). Milk retinol per gram fat at baseline did not differ by group; by 3 months after giving birth, milk retinol per gram fat was higher in the FO group than in the NFO group (p = 0.02) and remained higher throughout the 6 months (p < 0.0001). The combination of supplementation and fortification has a more sustained impact on milk retinol concentrations than supplementation alone, which did not have a sustained impact on milk VA concentrations. The fortification approach seems to be more effective for maintaining adequate milk VA concentrations among lactating Moroccan women. Fortification seems to be a long-term solution for the problem of VA deficiency, especially among women in low-income communities.