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BACKGROUND: Diabetes is associated with low plasma vitamin C concentrations. OBJECTIVES: We investigated the contribution of dysregulated vitamin C renal physiology, its prevalence, and associated clinical characteristics. METHODS: An essential prerequisite was determination of normal vitamin C renal threshold, the plasma concentration at which vitamin C first appears in urine. Using data from 17 healthy participants who underwent vitamin C depletion–repletion studies with a vitamin C dose range of 15–1250 mg daily, renal threshold was estimated using physiology-based pharmacokinetics modeling. Applying renal threshold 95% CIs, we estimated the minimal elimination threshold, the plasma concentration below which no vitamin C was expected in urine of healthy people. Renal leak was defined as abnormal presence of vitamin C in urine with plasma concentrations below the minimal elimination threshold. Criteria were tested in a cross-sectional cohort study of individuals with diabetes (82) and nondiabetic controls (80) using matched plasma and urine samples. RESULTS: Vitamin C renal thresholds in healthy men and women were [mean (SD)] 48.5 (5.2) µM and 58.3 (7.5) µM, respectively. Compared with nondiabetic controls, participants with diabetes had significantly higher prevalence of vitamin C renal leak (9% compared with 33%; OR: 5.07; 95% CI: 1.97, 14.83; P

In computed tomography (CT) images, pulmonary lobe segmentation is an arduous task due to its complex structures. To remedy the problem, we introduce a new framework based on lung anatomy knowledge for lung lobe segmentation. Firstly, the priori knowledge of lung anatomy is used to identify the fissure region of interest. Then, an oriented derivative of stick filter is applied to isolate plate-like structures from clutters for lobar fissure verification. Finally, a surface fitting model is employed to complete the incomplete fissure surface for lung lobe segmentation. Compared with manually segmented fissure references, the designed approach obtained a high median F1-score of 0.8865 in the left lung and obtained a high median F1-score of 0.9200 in the right lung. The average percentages of the segmented lung lobes in the lung lobe ground truth are 0.960, 0.989, 0.973, 0.920, and 0.985 for the left upper, left lower, right upper, right middle, and right lower lobes, respectively. The perfect performance of the proposed scheme is tested by visual inspection and quantitative evaluation.

This paper presents a novel differential evolution (DE) algorithm, with its improved version (IDE) for the benchmark functions and the optimal reactive power dispatch (ORPD) problem. Minimization of the total active power loss is usually considered as the objective function of the ORPD problem. The constraints involved are generators, transformers tapings, shunt reactors, and other reactive power sources. The aim of this study is to discover the best vector of control variables to minimize power loss, under the premise of considering the constraints system. In the proposed IDE, a new initialization strategy is developed to construct the initial population for guaranteeing its quality and simultaneously maintaining its diversity. In addition, to enhance the convergence characteristic of the original DE, two kinds of self-adaptive adjustment strategies are employed to update the scaling factor and the crossover factor, respectively, in which the detailed information about the two factors can be exchanged for each generation dynamically. Numerical applications of different cases are carried out on several benchmark functions and two standard IEEE systems, i.e., 14-bus and 30-bus test systems. The results achieved by using the proposed IDE, compared with other optimization algorithms, are discussed and analyzed in detail. The obtained results demonstrated that the proposed IDE can successfully be used to deal with the ORPD problem.

Background People with diabetes have lower plasma vitamin C concentrations compared to nondiabetic individuals. The prevalence of urinary vitamin C loss, and its relationship to plasma vitamin C concentrations are unknown. Methods In this cross-sectional cohort study of 162 individuals; 82 with diabetes and 80 nondiabetic controls, we investigated the prevalence and clinical characteristics of vitamin C renal leak, using fasting plasma and matched 1h urine samples. Based on vitamin C renal threshold, vitamin C renal leak was defined as presence of vitamin C in urine with plasma concentrations less than the minimal elimination threshold (MET) of 43.2µM in women or 38.1µM in men. We also assessed group differences in mean plasma vitamin C concentrations and investigated the association between diabetes-related clinical variables and renal leak. Vitamin C in plasma and urine was measured using coulometric electrochemical detection with high performance liquid chromatography. Results When compared with nondiabetic controls, subjects with diabetes had significantly increased prevalence of vitamin C renal leak (8.8% vs 32.9%: OR5, p Conclusion Increased prevalence of vitamin C renal leak in diabetes is associated with reduced plasma vitamin C concentrations. Glycemic control, microvascular complications, obesity, and proteinuria were associated with renal leak. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Priori knowledge of pulmonary anatomy plays a vital role in diagnosis of lung diseases. In CT images, pulmonary fissure segmentation is a formidable mission due to various of factors. To address the challenge, an useful approach based on ODoS filter and shape features is presented for pulmonary fissure segmentation. Here, we adopt an ODoS filter by merging the orientation information and magnitude information to highlight structure features for fissure enhancement, which can effectively distinguish between pulmonary fissures and clutters. Motivated by the fact that pulmonary fissures appear as linear structures in 2D space and planar structures in 3D space in orientation field, an orientation curvature criterion and an orientation partition scheme are fused to separate fissure patches and other structures in different orientation partition, which can suppress parts of clutters. Considering the shape difference between pulmonary fissures and tubular structures in magnitude field, a shape measure approach and a 3D skeletonization model are combined to segment pulmonary fissures for clutters removal. When applying our scheme to 55 chest CT scans which acquired from a publicly available LOLA11 datasets, the median F1-score, False Discovery Rate (FDR), and False Negative Rate (FNR) respectively are 0.896, 0.109, and 0.100, which indicates that the presented method has a satisfactory pulmonary fissure segmentation performance.

In order to maintain sustainable agriculture, the flow in irrigation systems needs to be managed remotely and finely to achieve efficient use of water resources. This research develops a flow measuring device that integrates measurement and control to achieve precise flow regulation under remote control. The device chooses the angular regulating valve as the actuation component to control the flow. By the experimental study of the valve body working characteristics, this paper (1) establishes the relationships among the pressure in front of the valve, the valve body opening and the pipeline flow; (2) establishes the relationship between the valve opening degree and the number of driving pulses of the stepper motor, and (3) designs the opening decision and flow measurement software. The experiment shows that the flow coefficient of the valve body is 84.61, and there is no leakage loss when closed. It also shows that the regulation curve matches the law of fast-opening features. The established relationship and the correlation coefficient between the performance parameters and the measured value are both greater than 0.99, indicating a decent performance of fitness. In a test where the pipeline pressures were 0.10, 0.20, and 0.30 MPa, the average duration of flow regulation was 62.48 s, with a maximum overshoot of 5%, and a maximum steady-state error of 6%. The experiment also showed that the higher the pressure is, the better the regulation effect is. The flow measurement error under varied pressure is below 3%. With its simple structure, fast flow regulation time, and high accuracy, this device meets the requirements of flow management in irrigation systems. It can be used in a variety of flow rate remote monitoring and control scenarios.

Background: Non-small cell lung cancer (NSCLC) remains the first leading cause of death in malignancies worldwide. Despite the early screening of NSCLC by low-dose spiral computed tomography (CT) in high-risk individuals caused a 20% reduction in the mortality, there still exists imperative needs for the identification of novel biomarkers for the diagnosis and treatment of lung cancer. Methods: mRNA microarray datasets GSE19188, GSE33532, and GSE44077 were searched, and the differentially expressed genes (DEGs) were obtained using GEO2R. Functional and pathway enrichment analyses were performed for the DEGs using DAVID database. Protein-protein interaction (PPI) network was plotted with STRING and visualized by Cytoscape. Module analysis of the PPI network was done through MCODE. The overall survival (OS) analysis of genes from MCODE was performed with the Kaplan Meier-plotter. Results: A total of 221 DEGs were obtained, which were mainly enriched in the terms related to cell division, cell proliferation, and signal transduction. A PPI network was constructed, consisting of 221 nodes and 739 edges. A significant module including 27 genes was identified in the PPI network. Elevated expression of these genes was associated with poor OS of NSCLC patients, including UBE2T, UNF2, CDKN3, ANLN, CCNB2, and CKAP2L. The enriched functions and pathways included protein binding, ATP binding, cell cycle, and p53 signaling pathway. Conclusions: The DEGs in NSCLC have the potential to become useful targets for the diagnosis and treatment of NSCLC.

BACKGROUND Determining the human vitamin E [α-tocopherol (α-T)] requirement is difficult, and novel approaches to assess α-T absorption and trafficking are needed. OBJECTIVE We hypothesized that the dual-isotope technique, using 2 deuterium-labeled [intravenous (IV) d6- and oral d3-] α-T, would be effective in determining α-T fractional absorption. Further, defined liquid meal (DLM) fat or fasting would modulate α-T fractional absorption and lipoprotein transport. METHODS A 3-phase cr ossover design was used. At 0 h, participants received IV d6-α-T and consumed d3-α-T with a 600-kcal DLM (40% or 0% fat) followed by controlled meals or by the 0% fat DLM, a 12-h fast, and then controlled meals. Blood samples and fecal samples were collected at intervals and analyzed by LC-MS. Pharmacokinetic parameters were calculated from plasma tracer concentrations and enrichments. Fractional absorption was calculated from d3- to d6-α-T areas under the curve, from a novel mathematical model, and from the balance method (oral d3-α-T minus fecal d3-α-T excreted). RESULTS Estimated α-T fractional absorption during the 40% fat intervention was 55% ± 3% (mean ± SEM; n = 10), which was 9% less than during the 0% fat intervention (64% ± 3%, n = 10; P

OBJECTIVES: We hypothesized that meal fat co-administered with fat-soluble α-tocopherol (vitamin E) facilitates vitamin E absorption and increases relative bioavailability in the immediate post-prandial phase, when compared with non-fat meals. We tested this hypothesis using deuterated oral α-tocopherol co-administered with breakfast containing meal fat (40% group) and without meal fat (0% group) in hospitalized healthy women. We also evaluated the role of subsequent meals in modulating the vitamin E relative bioavailability by fasting patients for 12 h following a breakfast meal with 0% fat (0% fat-fasting group). We compared area under the curve (AUC) for oral d3-α-tocopherols %enrichment at 0–4 h, 0–12 h and 0–24 h. METHODS: Custom-synthesized deuterated d3-α-tocopherol was co-administered with breakfast meal with and without fat, with subsequent serial sampling. Enrolled subjects were healthy women hospitalized for 5–6 days at the NIH Clinical Research Center. RESULTS: The AUC0–4 h for 40% fat group was more than twice 0% fat group (6.4 ± 1.8 vs 2.3 ± 0.7). This difference was erased following ingestion of meals containing 30% fat at 4 h and 8 h post-dosing, with AUC0–12 h for 40% and 0% fat groups (96.8 ± 10.2 vs 107.4 ± 8.) and AUC0–24 h (254 ± 16.3 vs 301.8 ± 19.7). To evaluate the effect of fasting, we compared 0% fat group with 0% fat-fast groups. At 4 h and 8 h post-dosing, the 0% fat group received meals with 30% fat, while 0% fat-fast group remained in fasting state. We therefore predicted and found significantly higher AUC0–12 h in the 0% fat group compared with the 0% fat-fast (107.4 ± 8.1 vs 41.1 ± 5.2 P

BACKGROUND: The global obesity epidemic has sobering consequences to human health. Especially concerning is obesity-associated hepato-steatosis (HS), a common cause of chronic liver disease in the Americas and Western Europe that precedes non-alcoholic steatohepatitis (NASH). Maintenance of normal body weight is the only current means to prevent HS and NASH. We hypothesized that excess liver fat in obesity-associated HS could act as a pathophysiologic chemical depot for fat-soluble vitamins and alter normal physiology. Because clinical trials with Vitamin E (α-T) have shown that NASH partially responds to this supplement, we selected α-T as a model vitamin to test the sequestration hypothesis. INTERVENTIONS: Under an IND and IRB-approved protocol, two deuterium-labeled α-tocopherols (d3-α-T and d6-α-T) were administered orally and intravenously, respectively, to 10 healthy women and 6 women with HS. Serial blood samples obtained over 72 h were analyzed by LC-MS/MS. In parallel, we performed studies in hepatocytes in cell culture and mouse model. RESULTS: In healthy women who received oral d3- and intravenous d6-α-T, 85% of the initial plasma peak d6-α-T disappeared within 20 minute and reappeared in the plasma peaking between 6-8 h. Compared to healthy subjects, subjects with HS had similar d6-α-T entry rates into liver, but reduced release rates into plasma (p CONCLUSION: These findings suggest the unique role of the liver in vitamin E physiology which is dysregulated by excess liver fat (measured by magnetic resonance spectroscopy). Considered together, the findings imply that obesity-associated HS may produce unrecognized hepatic α-T sequestration, which might subsequently drive liver disease. The data here raise the intriguing possibility that timely α-T supplementation might attenuate progression of HS to NASH, perhaps by correcting an unrecognized fat-induced, localized, hepatic vitamin E deficiency prior to onset of inflammation, hepatitis, and fibrosis. Additionally, our findings raise the possibility that HS may similarly alter hepatic physiology of other fat-soluble vitamins.

BACKGROUND: We hypothesized that obesity-associated hepatosteatosis is a pathophysiological chemical depot for fat-soluble vitamins and altered normal physiology. Using α-tocopherol (vitamin E) as a model vitamin, pharmacokinetics and kinetics principles were used to determine whether excess liver fat sequestered α-tocopherol in women with obesity-associated hepatosteatosis versus healthy controls. METHODS: Custom-synthesized deuterated α-tocopherols (d(3)- and d(6)-α-tocopherols) were administered to hospitalized healthy women and women with hepatosteatosis under investigational new drug guidelines. Fluorescently labeled α-tocopherol was custom-synthesized for cell studies. RESULTS: In healthy subjects, 85% of intravenous d(6)-α-tocopherol disappeared from the circulation within 20 minutes but reappeared within minutes and peaked at 3–4 hours; d(3)- and d(6)-α-tocopherols localized to lipoproteins. Lipoprotein redistribution occurred only in vivo within 1 hour, indicating a key role of the liver in uptake and re-release. Compared with healthy subjects who received 2 mg, subjects with hepatosteatosis had similar d(6)-α-tocopherol entry rates into liver but reduced initial release rates (P < 0.001). Similarly, pharmacokinetics parameters were reduced in hepatosteatosis subjects, indicating reduced hepatic d(6)-α-tocopherol output. Reductions in kinetics and pharmacokinetics parameters in hepatosteatosis subjects who received 2 mg were echoed by similar reductions in healthy subjects when comparing 5- and 2-mg doses. In vitro, fluorescent-labeled α-tocopherol localized to lipid in fat-loaded hepatocytes, indicating sequestration. CONCLUSIONS: The unique role of the liver in vitamin E physiology is dysregulated by excess liver fat. Obesity-associated hepatosteatosis may produce unrecognized hepatic vitamin E sequestration, which might subsequently drive liver disease. Our findings raise the possibility that hepatosteatosis may similarly alter hepatic physiology of other fat-soluble vitamins. TRIAL REGISTRATION: ClinicalTrials.gov, NCT00862433. FUNDING: National Institute of Diabetes and Digestive and Kidney Diseases and NIH grants DK053213-13, DK067494, and DK081761.

Background: Variations in intestinal antioxidant membrane transporters are implicated in the initiation and progression of inflammatory bowel disease (IBD). Facilitated glucose transporter member 14 (GLUT14), encoded by the solute carrier family 2 member 14 (SLC2A14) gene, is a putative transporter for dehydroascorbic acid and glucose. Although information on the gene is limited, shorter and longer GLUT14 isoforms have been identified. We hypothesized that GLUT14 mediates glucose and dehydroascorbic acid uptake. If this function could be validated, then genetic variations may associate with IBD.Objective: This study aimed to determine the substrate(s) for the GLUT14 protein and interrogated genetic associations of SLC2A14 with IBD.Design: The uptake of radiolabeled substrates into Xenopus laevis oocytes expressing the 2 GLUT14 isoforms was assessed. Examination of gene-targeted genetic association in the Manitoba Inflammatory Bowel Disease Cohort Study was conducted through the genotyping of single nucleotide polymorphisms (SNPs) representing linkage blocks of the SLC2A14 gene.Results: Both GLUT14 isoforms mediated the uptake of dehydroascorbic acid and glucose into X. laevis oocytes. Three alleles in the SLC2A14 gene associated independently with IBD. The odds of having ulcerative colitis (UC) or Crohn disease (CD) were elevated in carriers of the SLC2A14 SNP rs2889504-T allele (OR: 3.60; 95% CI: 1.95, 6.64 and OR: 4.68; 95% CI: 2.78, 8.50, respectively). Similarly, the SNP rs10846086-G allele was associated with an increased risk of both UC and CD (OR: 2.91; 95% CI: 1.49, 5.68 and OR: 3.00; 95% CI: 1.55, 5.78, respectively). Moreover, the SNP rs12815313-T allele associated with increased susceptibility to CD and UC (OR: 2.12; 95% CI: 1.33, 3.36 and OR: 1.61; 95% CI: 1.01, 2.57, respectively).Conclusion: These findings strengthen the hypothesis that genetically determined local dysregulation of dietary vitamin C or antioxidants transport contributes to IBD development. These transporter proteins are targetable by dietary interventions, opening the avenue to a precision intervention for patients of specific genotypes with IBD. This trial was registered at clinicaltrials.gov as NCT03262649.

Decreased red cell deformability is characteristic of several disorders. In some cases, the extent of defective deformability can predict severity of disease or occurrence of serious complications. Ektacytometry uses laser diffraction viscometry to measure the deformability of red blood cells subject to either increasing shear stress or an osmotic gradient at a constant value of applied shear stress. However, direct deformability measurements are difficult to interpret when measuring heterogenous blood that is characterized by the presence of both rigid and deformable red cells. This is due to the inability of rigid cells to properly align in response to shear stress and results in a distorted diffraction pattern marked by an exaggerated decrease in apparent deformability. Measurement of the degree of distortion provides an indicator of the heterogeneity of the erythrocytes in blood. In sickle cell anemia, this is correlated with the percentage of rigid cells, which reflects the hemoglobin concentration and hemoglobin composition of the erythrocytes. In addition to measuring deformability, osmotic gradient ektacytometry provides information about the osmotic fragility and hydration status of erythrocytes. These parameters also reflect the hemoglobin composition of red blood cells from sickle cell patients. Ektacytometry measures deformability in populations of red cells and does not, therefore, provide information on the deformability or mechanical properties of individual erythrocytes. Regardless, the goal of the techniques described herein is to provide a convenient and reliable method for measuring the deformability and cellular heterogeneity of blood. These techniques may be useful for monitoring temporal changes, as well as disease progression and response to therapeutic intervention in several disorders. Sickle cell anemia is one well-characterized example. Other potential disorders where measurements of red cell deformability and/or heterogeneity are of interest include blood storage, diabetes, Plasmodium infection, iron deficiency, and the hemolytic anemias due to membrane defects.

Strategies to prevent diabetic microvascular angiopathy focus on the vascular endothelium. Because red blood cells (RBCs) are less deformable in diabetes, we explored an original concept linking decreased RBC deformability to RBC ascorbate and hyperglycemia. We characterized ascorbate concentrations from human and mouse RBCs and plasma, and showed an inverse relationship between RBC ascorbate concentrations and deformability, measured by osmotic fragility. RBCs from ascorbate deficient mice were osmotically sensitive, appeared as spherocytes, and had decreased β-spectrin. These aberrancies reversed with ascorbate repletion in vivo. Under physiologic conditions, only ascorbate's oxidation product dehydroascorbic acid (DHA), a substrate for facilitated glucose transporters, was transported into mouse and human RBCs, with immediate intracellular reduction to ascorbate. In vitro, glucose inhibited entry of physiologic concentrations of dehydroascorbic acid into mouse and human RBCs. In vivo, plasma glucose concentrations in normal and diabetic mice and humans were inversely related to respective RBC ascorbate concentrations, as was osmotic fragility. Human RBC β-spectrin declined as diabetes worsened. Taken together, hyperglycemia in diabetes produced lower RBC ascorbate with increased RBC rigidity, a candidate to drive microvascular angiopathy. Because glucose transporter expression, DHA transport, and its inhibition by glucose differed for mouse versus human RBCs, human experimentation is indicated.

Ascorbic acid has been shown to kill various cancer cell lines at pharmacologic concentrations. We found that Epstein-Barr virus (EBV)-positive Burkitt lymphoma (BL) cells were more susceptible to ascorbic acid-induced cell killing than EBV-negative BL cells or EBV-transformed lymphoblastoid cells (LCLs). Ascorbic acid did not induce apoptosis in any of the tested cells but did induce the production of reactive oxygen species and cell death. Previously, we showed that bortezomib, a proteasome inhibitor, induces cell death in LCLs and EBV-positive BL cells. We found that ascorbic acid is strongly antagonistic for ascorbic acid-induced cell death in LCLs and EBV-positive BL cells. Finally, ascorbic acid did not prolong survival of severe combined immunodefiency mice inoculated with LCLs either intraperitoneally or subcutaneously. Thus, while ascorbic acid was highly effective at killing EBV-positive BL cells and LCLs in vitro, it antagonized cell killing by bortezomib and was ineffective in an animal model.

Amphotericin B (Ampho B) is a fungicidal drug that causes cell wall injury. Pharmacological ascorbate induces the extracellular prooxidants, which might enter the Ampho B-induced cell wall porosity and act synergistically. We tested low-dose Ampho B with a short course of pharmacological ascorbate using a mouse model of sepsis preconditioned with an injection of Candida albicans 6 h prior to cecal ligation and puncture (CLP). In this model, candidemia reappeared as early as 6 h after CLP with a predictably high mortality rate. This characteristic mimics sepsis in the phase of immunosuppression in patients. Using the model, at 12- and 18-h post-CLP, we administered isotonic (pH neutralized) pharmacological ascorbate intravenously with low-dose Ampho B or sodium deoxycholate, vehicle-controlled, administered IP. The survival rate of low-dose Ampho B plus ascorbate was 53%, compared with

Vitamin C, an essential micronutrient and a critical cofactor for several intracellular enzymatic reactions, is actively transported across epithelial barriers through the sodium-dependent ascorbic acid transporter 1 (SLC23A1). The SLC23A1 gene encodes SLC23A1 transporter and is located on human chromosome 5q31.2 (138702885-138719039 compl.; NC_000005.9). Previously, the SLC23A1 transcript has been described as containing 15 exons, stretching over 16 kilobases; however, no alternative splice variant has been described yet. Variations in SLC23A1 gene would impact vitamin C dietary requirements and/or susceptibility to common complex diseases. We have, therefore, evaluated the existence of additional SLC23A1 transcripts in silico and examined the function of new transcript through Xenopus laevis oocytes injection. Here, we characterized a novel alternative first exon encoding a SLC23A1 isoform which is exclusive to human and is expressed in the small intestine. The novel SLC23A1 protein isoform adds 36 N-te...

Crosslinking and charring in the condensed phase of polymers during heating, processing, and/or burning are of central importance in their flame retardance and smoke suppression and in formulating polymeric compos ites. Combining with thermal analysis techniques (TGA, DSC), ethylene-vinyl acetate (EVA) copolymers and polyethylenes (HDPE, LDPE) with/without inor ganic phosphorus-containing additives, were selected as model systems for XPS studies of the charring process. A new parameter, Tgr, the transition tempera ture from mesophase to graphitic structure (graphite-like structure, GLS) of the char has been well-defined and determined by combination of core levels and valence bands in XPS. The reason for Tgr to be selected as a likely supplemen tary parameter for characterizing polymer charring in condensed phase is two fold : 1) a clear-cut phase transition; 2) at which temperature a highly cross linked network results. A special emphasis in the paper has been given to the roles of the oxygen atoms either introduced from an adventitious atmosphere or inherent Ac group itself. Along this line some features in both thermal degradation and flame retardance of polymers have been rationalized in terms of transition temperature Tgr.

Although vitamin C (ascorbate) is present in whole blood, measurements in red blood cells (RBCs) are problematic because of interference, instability, limited sensitivity, and sample volume requirements. We describe a new technique using HPLC with coulometric electrochemical detection for ascorbate measurement in RBCs of humans, wild-type mice, and mice unable to synthesize ascorbate. Exogenously added ascorbate was fully recovered even when endogenous RBC ascorbate was below the detection threshold (25 nM). Twenty microliters of whole blood or 10 μl of packed RBCs was sufficient for assay. RBC ascorbate was stable for 24 h from whole-blood samples at 4 °C. Processed, stored samples were stable for >1 month at −80 °C. Unlike other tissues, ascorbate concentrations in human and mouse RBCs were linear in relation to plasma concentrations (R = 0.8 and 0.9, respectively). In healthy humans, RBC ascorbate concentrations were 9–57 μM, corresponding to ascorbate plasma concentrations of 15–90 μM. Mouse data were similar. In human blood stored as if for transfusion, initial RBC ascorbate concentrations varied approximately sevenfold and decreased 50% after 6 weeks of storage under clinical conditions. With this assay, it becomes possible for the first time to characterize ascorbate function in relation to endogenous concentrations in RBCs.

Levels of the necessary nutrient vitamin C (ascorbate) are tightly regulated by intestinal absorption, tissue accumulation, and renal reabsorption and excretion. Ascorbate levels are controlled in part by regulation of transport through at least 2 sodium-dependent transporters: Slc23a1 and Slc23a2 (also known as Svct1 and Svct2, respectively). Previous work indicates that Slc23a2 is essential for viability in mice, but the roles of Slc23a1 for viability and in adult physiology have not been determined. To investigate the contributions of Slc23a1 to plasma and tissue ascorbate concentrations in vivo, we generated Slc23a1-/- mice. Compared with wild-type mice, Slc23a1-/- mice increased ascorbate fractional excretion up to 18-fold. Hepatic portal ascorbate accumulation was nearly abolished, whereas intestinal absorption was marginally affected. Both heterozygous and knockout pups born to Slc23a1-/- dams exhibited approximately 45% perinatal mortality, and this was associated with lower plasma ascorbate concentrations in dams and pups. Perinatal mortality of Slc23a1-/- pups born to Slc23a1-/- dams was prevented by ascorbate supplementation during pregnancy. Taken together, these data indicate that ascorbate provided by the dam influenced perinatal survival. Although Slc23a1-/- mice lost as much as 70% of their ascorbate body stores in urine daily, we observed an unanticipated compensatory increase in ascorbate synthesis. These findings indicate a key role for Slc23a1 in renal ascorbate absorption and perinatal survival and reveal regulation of vitamin C biosynthesis in mice.

3-Substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine were obtained regiospecifically in yields of 35-92% in one pot by reaction of 2-aminopyridines or 2-(or 4-)aminopyrimidines, respectively, with 1,2-bis(benzotriazolyl)-1,2-(dialkylamino)ethanes.