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https://www.readbyqxmd.com/read/28321545/tissue-distribution-of-oral-vitamin-b12-is-influenced-by-b12-status-and-b12-form-an-experimental-study-in-rats
#1
Linda S Kornerup, Sergey N Fedosov, Christian B Juul, Eva Greibe, Christian W Heegaard, Ebba Nexo
PURPOSE: Hydroxocobalamin (HOCbl) is the dominating Cbl form in food, whereas cyanocobalamin (CNCbl) is common in vitamin pills and oral supplements. This study compares single-dose absorption and distribution of oral HO[(57)Co]Cbl and CN[(57)Co]Cbl in Cbl-deficient and normal rats. METHODS: Male Wistar rats (7 weeks) were fed a 14-day diet with (n = 15) or without (n = 15) Cbl. We compared the uptakes of HO[(57)Co]Cbl (free or bound to bovine transcobalamin) and free CN[(57)Co]Cbl administered by gastric gavage (n = 5 in each diet group)...
March 20, 2017: European Journal of Nutrition
https://www.readbyqxmd.com/read/28183371/regular-breakfast-consumption-is-associated-with-higher-blood-vitamin-status-in-adolescents-the-helena-healthy-lifestyle-in-europe-by-nutrition-in-adolescence-study
#2
Juan Mielgo-Ayuso, Jara Valtueña, Magdalena Cuenca-García, Fréderic Gottrand, Christina Breidenassel, Marika Ferrari, Yannis Manios, Stefaan De Henauw, Kurt Widhalm, Anthony Kafatos, Mathilde Kersting, Inge Huybrechts, Luis A Moreno, Marcela González-Gross
OBJECTIVE: The present study aimed to examine the association between different breakfast consumption patterns and vitamin intakes and blood vitamin concentrations in European adolescents. DESIGN: Breakfast consumption was assessed by a questionnaire. Vitamin intake was calculated from two 24 h recalls. Blood vitamin and total homocysteine (tHcy) concentrations were analysed from fasting blood samples. SETTING: The European Commission-funded HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study...
February 10, 2017: Public Health Nutrition
https://www.readbyqxmd.com/read/28121320/organometallic-cobalamin-anticancer-derivatives-for-targeted-prodrug-delivery-via-transcobalamin-mediated-uptake
#3
Jeremie Rossier, Daniel Hauser, Emmanuel Kottelat, Barbara Rothen-Rutishauser, Fabio Zobi
Herein we report the synthesis of new water-soluble vitamin B12 prodrugs bearing metal complexes at the β-upper side of the cobalt center. A total of three derivatives with the general design {Co-C[triple bond, length as m-dash]C-bpy-M}, where M represents a cytotoxic metal complex, were prepared and tested for their cytotoxicity against MCF-7 breast cancer cells. The choice of the metal was oriented on the eminent Pt and promising Ru and Re species to demonstrate the general applicability of the approach...
January 25, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28055029/gastrointestinal-transcriptomic-response-of-metabolic-vitamin-b12-pathways-in-roux-en-y-gastric-bypass
#4
Priscila Sala, Giliane Belarmino, Raquel S Torrinhas, Natasha M Machado, Danielle C Fonseca, Graziela R Ravacci, Robson K Ishida, Ismael F M S Guarda, Eduardo G de Moura, Paulo Sakai, Marco A Santo, Ismael D C G da Silva, Claudia C A Pereira, Angela F Logullo, Steven Heymsfield, Daniel Giannella-Neto, Dan L Waitzberg
OBJECTIVES: Vitamin B12 (B12) deficiency after Roux-en-Y gastric bypass (RYGB) is highly prevalent and may contribute to postoperative complications. Decreased production of intrinsic factor owing to gastric fundus removal is thought to have a major role, but other components of B12 metabolism may also be affected. We evaluated changes in the expression levels of multiple B12 pathway-encoding genes in gastrointestinal (GI) tissues to evaluate the potential roles in contributing to post-RYGB B12 deficiency...
January 5, 2017: Clinical and Translational Gastroenterology
https://www.readbyqxmd.com/read/27999949/anemia-in-nephrotic-syndrome-approach-to-evaluation-and-treatment
#5
Franca Iorember, Diego Aviles
Nephrotic syndrome is one of the most common glomerular diseases that affect in children. Complications may occur in nephrotic syndrome as a result of the disease itself as well as its treatment. Most of these complications result from excessive urinary protein losses, and control of proteinuria is the most effective treatment strategy. Anemia is one of the many complications seen in patients with persistent nephrotic syndrome and may occur as a result of excessive urinary losses of iron, transferrin, erythropoietin, transcobalamin and/or metals...
December 21, 2016: Pediatric Nephrology: Journal of the International Pediatric Nephrology Association
https://www.readbyqxmd.com/read/27893837/cell-type-specific-modulation-of-cobalamin-uptake-by-bovine-serum
#6
Hua Zhao, Kalani Ruberu, Hongyun Li, Brett Garner
Tracking cellular 57Co-labelled cobalamin (57Co-Cbl) uptake is a well-established method for studying Cbl homeostasis. Previous studies established that bovine serum is not generally permissive for cellular Cbl uptake when used as a supplement in cell culture medium, whereas supplementation with human serum promotes cellular Cbl uptake. The underlying reasons for these differences are not fully defined. In the current study we address this question. We extend earlier observations by showing that fetal calf serum inhibits cellular 57Co-Cbl uptake by HT1080 cells (a fibrosarcoma-derived fibroblast cell line)...
2016: PloS One
https://www.readbyqxmd.com/read/27852614/peripheral-neuropathy-risk-and-a-transcobalamin-polymorphism-connecting-the-dots-between-excessive-folate-intake-and-disease-susceptibility
#7
Ralph Green
No abstract text is available yet for this article.
December 2016: American Journal of Clinical Nutrition
https://www.readbyqxmd.com/read/27824740/seven-patients-with-transcobalamin-deficiency-diagnosed-between-2010-and-2014-a-single-center-experience
#8
Zuhal K Yildirim, Ebba Nexo, Tony Rupar, Mustafa Büyükavci
Transcobalamin deficiency (OMIM 275350) is a rare autosomal recessive disease presenting with nonspecific clinical features in early infancy. We report the clinical and laboratory manifestations of 7 children diagnosed with transcobalamin deficiency. All patients were admitted between 2 and 4 months of age with anemia, thrombocytopenia, and hyperhomocysteinemia. The most common complaints at admission were pallor, weakness, and poor feeding. Genetic analysis was performed in 5 patients and it revealed the same homozygous mutation...
January 2017: Journal of Pediatric Hematology/oncology
https://www.readbyqxmd.com/read/27733392/transcobalamin-776c%C3%A2-g-polymorphism-is-associated-with-peripheral-neuropathy-in-elderly-individuals-with-high-folate-intake
#9
Hathairat Sawaengsri, Peter R Bergethon, Wei Qiao Qiu, Tammy M Scott, Paul F Jacques, Jacob Selhub, Ligi Paul
BACKGROUND: The 776C→G polymorphism of the vitamin B-12 transport protein transcobalamin gene (TCN2) (rs1801198; Pro259Arg) is associated with a lower holotranscobalamin concentration in plasma. This effect may reduce the availability of vitamin B-12 to tissues even when vitamin B-12 intake is adequate. Clinical outcomes associated with vitamin B-12 insufficiency could potentially be worsened by high folate intake. OBJECTIVE: We determined the association of the TCN2 776C→G polymorphism and folate intake with peripheral neuropathy in elders with normal plasma concentrations of vitamin B-12...
December 2016: American Journal of Clinical Nutrition
https://www.readbyqxmd.com/read/27700208/first-trimester-serum-levels-of-the-soluble-transcobalamin-receptor-holo-transcobalamin-and-total-transcobalamin-in-relation-to-preeclampsia-risk
#10
Omar Abuyaman, Niels Torring, Rima Obeid, Ebba Nexo
BACKGROUND: Human placenta expresses CD320, a receptor that ensures the uptake of holo-transcobalamin (holoTC). Soluble CD320 (sCD320) is present in the circulation and its concentration increases during pregnancy. AIMS: To investigate a possible association of sCD320, holoTC and total transcobalamin (TC) with the risk of subsequent preeclampsia using serum samples from asymptomatic first trimester pregnant women. Moreover, we aimed to establish reference intervals of the aforementioned biomarkers for first trimester pregnant women who remained healthy throughout pregnancy...
December 2016: Scandinavian Journal of Clinical and Laboratory Investigation
https://www.readbyqxmd.com/read/27577703/vitamin-b12-and-placental-expression-of-transcobalamin-in-pregnant-adolescents
#11
Alexander J Layden, Kimberly O O'Brien, Eva K Pressman, Elizabeth M Cooper, Tera R Kent, Julia L Finkelstein
BACKGROUND: Transcobalamin is a key placental protein involved in transport of vitamin B12 to the fetus. However, few data currently exist on the ability of the placenta to modify vitamin B12 transporter expression, particularly in high-risk populations such as pregnant adolescents. OBJECTIVE: This study was conducted to determine the impact of maternal and neonatal serum vitamin B12 concentrations on placental transcobalamin (TC) expression in a cohort of healthy pregnant adolescents in the United States...
September 2016: Placenta
https://www.readbyqxmd.com/read/27545030/-association-of-crohn-s-disease-with-transcobalamin-%C3%A2-gene-polymorphisms-and-serum-homocysteine-folate-and-vitamin-b12-levels-in-chinese-patients
#12
S Z Zheng, X P Xia, H Wu, X X Shao, X Q Lin, X L Wu, L J Jiang, R Ding, Y Jiang
OBJECTIVE: To investigate the association of Crohn's disease (CD) with transcobalamin Ⅱ (TCN2) gene polymorphisms and serum homocysteine (Hcy), folate, and vitamin B12 levels in Chinese patients. METHODS: In a total of 307 CD patients (CD group) and 574 healthy controls (control group) of Han ethnicity selected at 4 hospitals in Wenzhou between January 2007 and August 2015, TCN2 gene polymorphisms (rs1801198, C/G; rs9606756, A/G) in peripheral blood were determined using improved multiple ligase detection reaction (iMLDR)...
August 9, 2016: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/27446930/biomarkers-and-algorithms-for-the-diagnosis-of-vitamin-b12-deficiency
#13
REVIEW
Luciana Hannibal, Vegard Lysne, Anne-Lise Bjørke-Monsen, Sidney Behringer, Sarah C Grünert, Ute Spiekerkoetter, Donald W Jacobsen, Henk J Blom
Vitamin B12 (cobalamin, Cbl, B12) is an indispensable water-soluble micronutrient that serves as a coenzyme for cytosolic methionine synthase (MS) and mitochondrial methylmalonyl-CoA mutase (MCM). Deficiency of Cbl, whether nutritional or due to inborn errors of Cbl metabolism, inactivate MS and MCM leading to the accumulation of homocysteine (Hcy) and methylmalonic acid (MMA), respectively. In conjunction with total B12 and its bioactive protein-bound form, holo-transcobalamin (holo-TC), Hcy, and MMA are the preferred serum biomarkers utilized to determine B12 status...
2016: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/27411955/structural-basis-of-transcobalamin-recognition-by-human-cd320-receptor
#14
Amer Alam, Jae-Sung Woo, Jennifer Schmitz, Bernadette Prinz, Katharina Root, Fan Chen, Joël S Bloch, Renato Zenobi, Kaspar P Locher
Cellular uptake of vitamin B12 (cobalamin) requires capture of transcobalamin (TC) from the plasma by CD320, a ubiquitous cell surface receptor of the LDLR family. Here we present the crystal structure of human holo-TC in complex with the extracellular domain of CD320, visualizing the structural basis of the TC-CD320 interaction. The observed interaction chemistry can rationalize the high affinity of CD320 for TC and lack of haptocorrin binding. The in vitro affinity and complex stability of TC-CD320 were quantitated using a solid-phase binding assay and thermostability analysis...
July 14, 2016: Nature Communications
https://www.readbyqxmd.com/read/27350907/holotranscobalamin-holotc-active-b12-and-herbert-s-model-for-the-development-of-vitamin-b12-deficiency-a-review-and-alternative-hypothesis
#15
REVIEW
Paul Henry Golding
The concentration of total vitamin B12 in serum is not a sufficiently sensitive or specific indicator for the reliable diagnosis of vitamin B12 deficiency. Victor Herbert proposed a model for the staged development of vitamin B12 deficiency, in which holotranscobalamin (HoloTC) is the first indicator of deficiency. Based on this model, a commercial immunoassay has been controversially promoted as a replacement for the total vitamin B12 test. HoloTC is cobalamin (vitamin B12) attached to the transport protein transcobalamin, in the serum, for delivery to cells for metabolism...
2016: SpringerPlus
https://www.readbyqxmd.com/read/27349184/inborn-error-of-cobalamin-metabolism-associated-with-the-intracellular-accumulation-of-transcobalamin-bound-cobalamin-and-mutations-in-znf143-which-codes-for-a-transcriptional-activator
#16
Mihaela Pupavac, David Watkins, Francis Petrella, Somayyeh Fahiminiya, Alexandre Janer, Warren Cheung, Anne-Claude Gingras, Tomi Pastinen, Joseph Muenzer, Jacek Majewski, Eric A Shoubridge, David S Rosenblatt
Vitamin B12 (cobalamin, Cbl) cofactors adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl) are required for the activity of the enzymes methylmalonyl-CoA mutase (MCM) and methionine synthase (MS). Inborn errors of Cbl metabolism are rare Mendelian disorders associated with hematological and neurological manifestations, and elevations of methylmalonic acid and/or homocysteine in the blood and urine. We describe a patient whose fibroblasts had decreased functional activity of MCM and MS and decreased synthesis of AdoCbl and MeCbl (3...
September 2016: Human Mutation
https://www.readbyqxmd.com/read/27216769/quantification-of-2-methylcitric-acid-in-dried-blood-spots-improves-newborn-screening-for-propionic-and-methylmalonic-acidemias
#17
Osama Y Al-Dirbashi, Nathan McIntosh, Pranesh Chakraborty
BACKGROUND: Newborn screening for propionic acidemia and methylmalonic acidurias using the marker propionylcarnitine (C3) is neither sensitive nor specific. Using C3 to acetylcarnitine (C3/C2) ratio, together with conservative C3 cut-offs, can improve screening sensitivity, but the false positive rate remains high. Incorporating the marker 2-methylcitric acid has been suggested, to improve the positive predictive value for these disorders without compromising the sensitivity. METHODS: Between July 2011 and December 2012 at the Newborn Screening Ontario laboratory, all neonatal dried blood spot samples that were reported as screen positive for propionic acidemia or methylmalonic acidurias based on elevated C3 and C3/C2 ratio were analyzed for 2-methylcitric acid, using liquid chromatography tandem mass spectrometry...
May 22, 2016: Journal of Medical Screening
https://www.readbyqxmd.com/read/27169753/laboratory-assessment-of-vitamin-b12-status
#18
Dominic J Harrington
The detection and correction of vitamin B12 (B12) deficiency prevents megaloblastic anaemia and potentially irreversible neuropathy and neuropsychiatric changes. B12 status is commonly estimated using the abundance of the vitamin in serum, with ∼148 pmol/L (200 ng/L) typically set as the threshold for diagnosing deficiency. Serum B12 assays measure the sum of haptocorrin-bound and transcobalamin-bound (known as holotranscobalamin) B12 It is only holotranscobalamin that is taken up by cells to meet metabolic demand...
February 2017: Journal of Clinical Pathology
https://www.readbyqxmd.com/read/27155006/false-low-holotranscobalamin-levels-in-a-patient-with-a-novel-tcn2-mutation
#19
Peter Keller, Janine Rufener, Christof Schild, Sergey N Fedosov, Peter H Nissen, Ebba Nexo
BACKGROUND: Measurement of holotranscobalamin (holoTC) is increasingly used as a screening test for cobalamin (Cbl) deficiency. A level well below the reference interval strongly supports a deficient state. We examined a 21-year-old woman diagnosed as Cbl deficient because of an extremely low holoTC level as measured by the Abbott Architect Assay. METHODS: The patient was evaluated for Cbl deficiency employing an in-house holoTC method as well as other routine markers of Cbl status...
November 1, 2016: Clinical Chemistry and Laboratory Medicine: CCLM
https://www.readbyqxmd.com/read/26999557/low-holo-transcobalamin-levels-are-prevalent-in-vegetarians-and-is-associated-with-coronary-artery-disease-in-indian-population
#20
Trayambak Basak, Gaurav Garg, Nitin Bhardwaj, Vinay Singh Tanwar, Sandeep Seth, Ganesan Karthikeyan, Shantanu Sengupta
Coronary artery disease (CAD) has been increasing alarmingly in India. We had earlier shown that vitamin B12 deficiency is associated with CAD in Indian population. However, only about a quarter of the total vitamin B12 is internalised in the cells by the proteins transcobalamin II. Vitamin B12-bound transcobalamin II (holotranscobalamin, holoTC) is thus referred to as biologically active B12. In this study, we ascertained the levels of holoTC in 501 CAD cases and 1253 healthy controls and for the first time show that holoTC levels are significantly lower (p = 2...
July 2016: Biomarkers: Biochemical Indicators of Exposure, Response, and Susceptibility to Chemicals
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