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Ebba Nexo - One of the best experts on this subject based on the ideXlab platform.
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Cobalamin and Haptocorrin in human milk and cobalamin-related variables in mother and child: a 9-mo longitudinal study
The American journal of clinical nutrition, 2013Co-Authors: Eva Greibe, Dorte L. Lildballe, S. Streym, Peter Vestergaard, Lars Rejnmark, Leif Mosekilde, Ebba NexoAbstract:Background: Measurement of milk cobalamin is hampered by the high content of the cobalamin-binding protein Haptocorrin, and limited data are available relating trustworthy measures of milk cobalamin to cobalamin status in healthy mothers and their children. Objectives: The objectives were to explore the concentration of cobalamin and Haptocorrin in foremilk and hindmilk during the first 9 mo of lactation and to relate these results to biomarkers of an impaired cobalamin status of mother and child. Design: Milk samples from 25 mothers were collected at 2 wk, 4 mo, and 9 mo postpartum for the measurement of cobalamin and Haptocorrin. Plasma samples from a larger cohort of lactating mothers (n = 107) and their infants (n = 108) were collected at the same time points for the measurement of cobalamin, holotranscobalamin, total transcobalamin, total Haptocorrin, and methylmalonic acid. Results: Median (range) concentrations of cobalamin in hindmilk were 760 (210‐1880), 290 (140‐690), and 440 (160‐1940) pmol/L at 2 wk, 4 mo, and 9 mo, respectively; the respective Haptocorrin concentrations were 25 (9‐102), 22 (4‐100), and 180 (30‐460) nmol/L. We found slightly lower values in foremilk. A decrease in milk cobalamin at 4 mo was associated with decreases in plasma cobalamin (P , 0.0001) and holotranscobalamin (P , 0.0001) in the infants. Strong positive associations in paired maternal-infant cobalamin concentrations were found at all time points. Conclusions: Foremilk and hindmilk contained comparable amounts of cobalamin and Haptocorrin, but marked changes were observed during 9 mo of lactation. At 4 mo, low concentrations of milk cobalamin mirrored biochemical changes in infants, which suggests an impaired cobalamin status and indicates that nutrition from only mother’s milk may not be sufficient for the supply of cobalamin from this age. This trial was registered by the Danish Data Protection Agency at www.datatilsynet.dk/english as 200841-2185. Am J Clin Nutr doi: 10.3945/ajcn.113.058479.
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Cobalamin analogues in humans: a study on maternal and cord blood.
PloS one, 2013Co-Authors: Tore Forsingdal Hardlei, Rima Obeid, Wolfgang A. Herrmann, Ebba NexoAbstract:Background Haptocorrin (HC) carries cobalamin analogues (CorA), but whether CorA are produced in the body is unknown. All cobalamins (Cbl) to the foetus are delivered by the Cbl-specific protein transcobalamin (TC), and therefore analysis of cord serum for CorA may help to clarify the origin of CorA.
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Three family members with elevated plasma cobalamin, transcobalamin and soluble transcobalamin receptor (sCD320).
Clinical chemistry and laboratory medicine, 2013Co-Authors: Elke Hoffmann-lücke, Johan F. B. Arendt, Peter H. Nissen, Gustav Mikkelsen, Jan Aasly, Ebba NexoAbstract:BACKGROUND Plasma cobalamin is requested in order to diagnose cobalamin deficiency and low levels confirm a deficient state. Here, we present three family members with unexpected high levels of cobalamin. METHODS We included a patient referred for cobalamin measurement due to neurological symptoms, her son and her daughter. Mother and son both suffered from myotonic dystrophy type II, while the daughter tested negative for this disease. Blood samples were analyzed for cobalamin, Haptocorrin, transcobalamin, holoTC, and sCD320. We employed gel filtration and antibody precipitation for further characterization. The protein coding region of the TCN2 gene, encoding transcobalamin, was sequenced. RESULTS The patient, her {son} and [daughter] all had cobalamin levels above the measurement range of the routine method employed (>1476 pmol/L). Total transcobalamin and (holoTC) were 5980 (1500), {5260 (2410)} and [5630 (1340)] pmol/L, which is well above the upper reference limits of 1500 (160) pmol/L. The sCD320 concentration was also well above the upper reference limit of 97 arb.u.: 1340, {1510} and [1090] arb.u. Haptocorrin levels were within the reference range and no signs of cobalamin deficiency were found. DNA sequencing of the TCN2 gene revealed several known polymorphisms not associated with highly elevated transcobalamin levels. Upon gel filtration, sCD320 eluted as a larger molecule than previously reported. By incubation with anti-transcobalamin antibodies, we precipitated both transcobalamin and part of sCD320. CONCLUSIONS The high cobalamin levels were mainly explained by high levels of holoTC, possibly caused by complex formation with its soluble receptor, sCD320. The family occurrence points to a genetic explanation.
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Cobalamin Related Parameters and Disease Patterns in Patients with Increased Serum Cobalamin Levels
PloS one, 2012Co-Authors: Johan F. B. Arendt, Ebba NexoAbstract:Background: Measurement of serum cobalamin levels is routinely used to diagnose cobalamin deficiency. Surprisingly, approximately 15% of patients have high cobalamin levels and no consensus exists regarding the clinical implications. Methods: Hospital-treated patients above 18 years of age referred for serum cobalamin measurement were included in groups of patients [percentage cobalamin supplemented] with low (,200 pmol/L, n=200 [6%]), normal (200–600, n=202 [6%]) high (601–1000, n=217 [27%]) and very high (.1000, n=199 [53%]) cobalamin levels. Total and cobalamin-saturated (holo) transcobalamin, total Haptocorrin, soluble TC receptor, sCD320, and methylmalonic acid were analyzed. Data on diagnoses and medical prescriptions was obtained through medical files and the Aarhus University Prescription Database. Results: Among patients not cobalamin supplemented median total Haptocorrin and holo transcobalamin levels were markedly higher in the groups with high/very high cobalamin levels compared to groups with low/normal cobalamin levels. Median total transcobalamin and sCD320 levels were similar across the groups. A number of diagnoses were significantly associated to very high Cbl levels (odds ratio (95% confidence interval)): alcoholism (5.74 (2.76–11.96)), liver disease (8.53 (3.59–20.23)), and cancer (5.48 (2.85–10.55)). Elevated Haptocorrin levels were seen in patients with alcoholism, cancer, liver-, renal-, autoimmune-, and bronchopulmonary disease. No clinical associations to sCD320 and total and holo transcobalamin levels were found. Conclusion: In non-supplemented patients, high cobalamin levels were associated to high Haptocorrin levels, and several diagnoses, including alcoholism, liver disease and cancer. Our study emphasizes that clinicians should take high serum cobalamin levels into consideration in the diagnostic process.
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A single rainbow trout cobalamin-binding protein stands in for three human binders.
The Journal of biological chemistry, 2012Co-Authors: Eva Greibe, Boe Sandahl Sorensen, Sergey N. Fedosov, Steen Seier Poulsen, Peter Højrup, Ebba NexoAbstract:Cobalamin uptake and transport in mammals are mediated by three cobalamin-binding proteins: Haptocorrin, intrinsic factor, and transcobalamin. The nature of cobalamin-binding proteins in lower vertebrates remains to be elucidated. The aim of this study was to characterize the cobalamin-binding proteins of the rainbow trout (Oncorhynchus mykiss) and to compare their properties with those of the three human cobalamin-binding proteins. High cobalamin-binding capacity was found in trout stomach (210 pmol/g), roe (400 pmol/g), roe fluid (390 nmol/liter), and plasma (2500 nmol/liter). In all cases, it appeared to be the same protein based on analysis of partial sequences and immunological responses. The trout cobalamin-binding protein was purified from roe fluid, sequenced, and further characterized. Like Haptocorrin, the trout cobalamin-binding protein was stable at low pH and had a high binding affinity for the cobalamin analog cobinamide. Like Haptocorrin and transcobalamin, the trout cobalamin-binding protein was present in plasma and recognized ligands with altered nucleotide moiety. Like intrinsic factors, the trout cobalamin-binding protein was present in the stomach and resisted degradation by trypsin and chymotrypsin. It also resembled intrinsic factor in the composition of conserved residues in the primary cobalamin-binding site in the C terminus. The trout cobalamin-binding protein was glycosylated and displayed spectral properties comparable with those of Haptocorrin and intrinsic factor. In conclusion, only one soluble cobalamin-binding protein was identified in the rainbow trout, a protein that structurally behaves like an intermediate between the three human cobalamin-binding proteins.
Bo Lönnerdal - One of the best experts on this subject based on the ideXlab platform.
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Human Milk Proteins
Advances in Experimental Medicine and Biology, 2004Co-Authors: Bo LönnerdalAbstract:Human milk contains a wide array of proteins that provide biologic activities ranging from antimicrobial effects to immunostimulatory functions. Proteins like lactoferrin, secretory IgA, κ-casein, lactoperoxidase, Haptocorrin, lactadherin and peptides formed from human milk proteins during digestion can inhibit the growth of pathogenic bacteria and viruses and therefore protect against infection. At the same time, proteins like lactoferrin, bile-salt stimulated lipase, Haptocorrin, κ-casein, and folate-binding protein can facilitate the absorption of nutrients in the neonatal gut. However, the proteins in human milk themselves also provide adequate amounts of essential amino acids to the growing infant. This suggests a highly adapted digestive system, which allows the survival of some proteins and peptides in the upper gastrointestinal tract, while still allowing amino acid utilization from these proteins further down in the gut. It is now possible to produce recombinant human milk proteins in transgenic plants and animals, which makes it possible to further study the bioactivity of these proteins. Provided these proteins can be produced in large scale at low cost, that they show biologic activity and pose no safety concerns, it may be possible to add some human milk proteins to infant diets, such as formula and complementary foods. Human milk proteins produced in rice or potatoes, for example, could be added without much purification, because these staples commonly are used in weaning foods. Thus, some qualities provided by human milk may be included into other diets, although it is highly unlikely that all unique components of human milk can be copied this way.
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Human milk proteins: key components for the biological activity of human milk.
Advances in experimental medicine and biology, 2004Co-Authors: Bo LönnerdalAbstract:Human milk contains a wide array of proteins that provide biologic activities ranging from antimicrobial effects to immunostimulatory functions. Proteins like lactoferrin, secretory IgA, kappa-casein, lactoperoxidase, Haptocorrin, lactadherin and peptides formed from human milk proteins during digestion can inhibit the growth of pathogenic bacteria and viruses and therefore protect against infection. At the same time, proteins like lactoferrin, bile-salt stimulated lipase, Haptocorrin, kappa-casein, and folate-binding protein can facilitate the absorption of nutrients in the neonatal gut. However, the proteins in human milk themselves also provide adequate amounts of essential amino acids to the growing infant. This suggests a highly adapted digestive system, which allows the survival of some proteins and peptides in the upper gastrointestinal tract, while still allowing amino acid utilization from these proteins further down in the gut. It is now possible to produce recombinant human milk proteins in transgenic plants and animals, which makes it possible to further study the bioactivity of these proteins. Provided these proteins can be produced in large scale at low cost, that they show biologic activity and pose no safety concerns, it may be possible to add some human milk proteins to infant diets, such as formula and complementary foods. Human milk proteins produced in rice or potatoes, for example, could be added without much purification, because these staples commonly are used in weaning foods. Thus, some qualities provided by human milk may be included into other diets, although it is highly unlikely that all unique components of human milk can be copied this way.
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Potential host-defense role of a human milk vitamin B-12–binding protein, Haptocorrin, in the gastrointestinal tract of breastfed infants, as assessed with porcine Haptocorrin in vitro
The American journal of clinical nutrition, 2003Co-Authors: Yuriko Adkins, Bo LönnerdalAbstract:Background: Limited information exists on the biological role of a vitamin B-12-binding protein, Haptocorrin, in human milk. The expression of Haptocorrin by human mammary epithelial cells and its presence in human milk suggest a potential physiologic function in breastfed infants. Objective: We investigated the extent to which Haptocorrin could withstand proteolytic degradation and exert antimicrobial activity under in vitro conditions designed to simulate the gastrointestinal tract of breastfed infants. Design: An in vitro model that simulates infant gastric and intestinal digestion was developed. The structural stability of porcine Haptocorrin after exposure to digestive enzymes (pepsin and pancreatin) was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot analysis, column chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The antimicrobial activity of Haptocorrin was determined by incubating Haptocorrin with enteropathogenic Escherichia coli 0127 strain 2348/69 and monitoring bacterial growth. Results: The structural analysis of Haptocorrin exposed to enzymes did not show a decrease in molecular weight, which indicated that Haptocorrin can survive proteolytic degradation. Both Haptocorrin exposed to digestive enzymes and undigested Haptocorrin inhibited the growth of enteropathogenic E. coli and did so to a similar extent. Thus, Haptocorrin in vitro not only retains its structure after exposure to proteases but also exhibits antimicrobial activity. Conclusion: These results suggest that Haptocorrin may exert a host-defense function against pathogens in the gastrointestinal tracts of breastfed infants.
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potential host defense role of a human milk vitamin b 12 binding protein Haptocorrin in the gastrointestinal tract of breastfed infants as assessed with porcine Haptocorrin in vitro
The American Journal of Clinical Nutrition, 2003Co-Authors: Yuriko Adkins, Bo LönnerdalAbstract:Background: Limited information exists on the biological role of a vitamin B-12-binding protein, Haptocorrin, in human milk. The expression of Haptocorrin by human mammary epithelial cells and its presence in human milk suggest a potential physiologic function in breastfed infants. Objective: We investigated the extent to which Haptocorrin could withstand proteolytic degradation and exert antimicrobial activity under in vitro conditions designed to simulate the gastrointestinal tract of breastfed infants. Design: An in vitro model that simulates infant gastric and intestinal digestion was developed. The structural stability of porcine Haptocorrin after exposure to digestive enzymes (pepsin and pancreatin) was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot analysis, column chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The antimicrobial activity of Haptocorrin was determined by incubating Haptocorrin with enteropathogenic Escherichia coli 0127 strain 2348/69 and monitoring bacterial growth. Results: The structural analysis of Haptocorrin exposed to enzymes did not show a decrease in molecular weight, which indicated that Haptocorrin can survive proteolytic degradation. Both Haptocorrin exposed to digestive enzymes and undigested Haptocorrin inhibited the growth of enteropathogenic E. coli and did so to a similar extent. Thus, Haptocorrin in vitro not only retains its structure after exposure to proteases but also exhibits antimicrobial activity. Conclusion: These results suggest that Haptocorrin may exert a host-defense function against pathogens in the gastrointestinal tracts of breastfed infants.
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Nutritional and physiologic significance of human milk proteins.
The American journal of clinical nutrition, 2003Co-Authors: Bo LönnerdalAbstract:Human milk contains a wide variety of proteins that contribute to its unique qualities. Many of these proteins are digested and provide a well-balanced source of amino acids to rapidly growing infants. Some proteins, such as bile salt-stimulated lipase, amylase, beta-casein, lactoferrin, Haptocorrin, and alpha(1)-antitrypsin, assist in the digestion and utilization of micronutrients and macronutrients from the milk. Several proteins with antimicrobial activity, such as immunoglobulins, kappa-casein, lysozyme, lactoferrin, Haptocorrin, alpha-lactalbumin, and lactoperoxidase, are relatively resistant against proteolysis in the gastrointestinal tract and may, in intact or partially digested form, contribute to the defense of breastfed infants against pathogenic bacteria and viruses. Prebiotic activity, such as the promotion of the growth of beneficial bacteria such as Lactobacilli and Bifidobacteria, may also be provided by human milk proteins. This type of activity can limit the growth of several pathogens by decreasing intestinal pH. Some proteins and peptides have immunomodulatory activities (eg, cytokines and lactoferrin), whereas others (eg, insulin-like growth factor, epidermal growth factor, and lactoferrin) are likely to be involved in the development of the intestinal mucosa and other organs of newborns. In combination, breast-milk proteins assist in providing adequate nutrition to breastfed infants while simultaneously aiding in the defense against infection and facilitating optimal development of important physiologic functions in newborns.
Anne L Morkbak - One of the best experts on this subject based on the ideXlab platform.
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Uptake of cobalamin and markers of cobalamin status: a longitudinal study of healthy pregnant women.
Clinical chemistry and laboratory medicine, 2011Co-Authors: Eva Greibe, Anne L Morkbak, Dorte L. Lildballe, Birgitte Horst Andreasen, Anne-mette Hvas, Ebba NexoAbstract:BACKGROUND Currently, it is unknown whether the decline in plasma cobalamin observed during pregnancy is caused by malabsorption of the vitamin. This study examined cobalamin absorption and markers of cobalamin status during normal pregnancy. METHODS Twenty-seven pregnant Danish women were examined at gestation weeks 13, 24 and 36. The absorption test CobaSorb was performed in all women implying measurement of holotranscobalamin or cyanocobalamin bound to transcobalamin before and after 2 days intake of 3 × 9 μg cobalamin. Serum cobalamin and the two cobalamin binding proteins transcobalamin and Haptocorrin, including Haptocorrin saturated with cobalamin or analogues, were measured, and so was plasma methylmalonic acid and homocysteine. RESULTS No change in the uptake of cobalamin was observed throughout pregnancy. Serum cobalamin displayed a gradual decline during pregnancy (p
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Haptocorrin in humans
Clinical Chemistry and Laboratory Medicine, 2007Co-Authors: Anne L Morkbak, Steen Seier Poulsen, Ebba NexoAbstract:Background: Evolutionary Haptocorrin is the youngest of the cobalamin-binding proteins. It evolved by duplication of the intrinsic factor gene and has been identified in most mammals examined. Its ability to bind both cobalamin and analogues is well established, but apart from that, our knowledge concerning its function and its distribution in adult and foetal life is limited. In this study, we present data on the tissue expression of Haptocorrin and on the relation between analogues on Haptocorrin and vitamin B 12 status in humans. Methods: Polyclonal antibodies towards Haptocorrin were used to study the localisation in foetal and adult tissues by immunohistochemistry. Positive immuno-reactions were primarily observed in exocrine glands, the gastrointestinal tract and the respiratory system. ELISA was used for measurement of holo- and total Haptocorrin in blood samples from individuals diagnosed with vitamin B 12 deficiency, based on measurement of methylmalonic acid μmol/L) as evident (>0.75, n=61), suspected (0.29-0.75, n=155) or not present (<0.29, n=170). Cobalamins and holotranscobalamin were measured in the same individuals. Results: HoloHaptocorrin was considerably higher than holoHaptocorrin-cobalamins (cobalamins minus holotranscobalamin). The median (25th-75th percentile, pmol/L) for holoHaptocorrin analogues (holoHaptocorrin minus holoHaptocorrin-cobalamins) was higher in deficient [200 (130-240)] compared to the non-deficient [140 (80-200)] individuals (analysis of variance and Tukey's multiple comparison test, p<0.01). Conclusions: Our results indicate that Haptocorrin is widely distributed also in foetal tissues and suggest analogues to accumulate on Haptocorrin in vitamin B 12 -deficient individuals, a result that warrants further studies employing methods directly measuring cobalamins and analogues attached to Haptocorrin.
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Haptocorrin in humans.
Clinical chemistry and laboratory medicine, 2007Co-Authors: Anne L Morkbak, Steen Seier Poulsen, Ebba NexoAbstract:Background: Evolutionary Haptocorrin is the youngest of the cobalamin-binding proteins. It evolved by duplication of the intrinsic factor gene and has been identified in most mammals examined. Its ability to bind both cobalamin and analogues is well established, but apart from that, our knowledge concerning its function and its distribution in adult and foetal life is limited. In this study, we present data on the tissue expression of Haptocorrin and on the relation between analogues on Haptocorrin and vitamin B 12 status in humans. Methods: Polyclonal antibodies towards Haptocorrin were used to study the localisation in foetal and adult tissues by immunohistochemistry. Positive immuno-reactions were primarily observed in exocrine glands, the gastrointestinal tract and the respiratory system. ELISA was used for measurement of holo- and total Haptocorrin in blood samples from individuals diagnosed with vitamin B 12 deficiency, based on measurement of methylmalonic acid μmol/L) as evident (>0.75, n=61), suspected (0.29-0.75, n=155) or not present (
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Effect of Vitamin B12 Treatment on Haptocorrin
Clinical chemistry, 2006Co-Authors: Anne L Morkbak, Helga Refsum, Anne-mette Hvas, Thomas A. B. Sanders, Zouë Lloyd-wright, Øyvind Bleie, Ottar Nygaard, Ebba NexoAbstract:Background: Haptocorrin (HC) carries the major part of circulating cobalamin, but whether HC is altered on treatment with vitamin B12 remains unknown. Methods: Our study included 3 populations: a population of vegan men (n = 174; vegan population), of whom 63 were treated daily with 5 mg of oral vitamin B12 for 3 months; a group of patients with a previous methylmalonic acid (MMA) concentration >0.4 μmol/L (n = 140; population with suspected deficiency), of which 69 were treated with weekly vitamin B12 injections (1 mg) for 4 weeks; and a subgroup of participants in a vitamin B intervention study (n = 88; nondeficient population), of whom 45 were treated daily with 0.4 mg of oral vitamin B12 for 3 months. Total HC and holoHC were measured by ELISA. Cobalamin was measured by an intrinsic factor (IF)-based assay. Samples were collected at baseline and 3 months after start of treatment. Results: Compared with baseline results for the 3 study populations, total HC and holoHC increased 30 pmol/L for every 100 pmol/L increase in cobalamin. After treatment with vitamin B12, holoHC ( P
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effect of vitamin b12 treatment on Haptocorrin
Clinical Chemistry, 2006Co-Authors: Anne L Morkbak, Helga Refsum, Anne-mette Hvas, Thomas A. B. Sanders, Øyvind Bleie, Ottar Nygaard, Zoue LloydwrightAbstract:Background: Haptocorrin (HC) carries the major part of circulating cobalamin, but whether HC is altered on treatment with vitamin B12 remains unknown. Methods: Our study included 3 populations: a population of vegan men (n = 174; vegan population), of whom 63 were treated daily with 5 mg of oral vitamin B12 for 3 months; a group of patients with a previous methylmalonic acid (MMA) concentration >0.4 μmol/L (n = 140; population with suspected deficiency), of which 69 were treated with weekly vitamin B12 injections (1 mg) for 4 weeks; and a subgroup of participants in a vitamin B intervention study (n = 88; nondeficient population), of whom 45 were treated daily with 0.4 mg of oral vitamin B12 for 3 months. Total HC and holoHC were measured by ELISA. Cobalamin was measured by an intrinsic factor (IF)-based assay. Samples were collected at baseline and 3 months after start of treatment. Results: Compared with baseline results for the 3 study populations, total HC and holoHC increased 30 pmol/L for every 100 pmol/L increase in cobalamin. After treatment with vitamin B12, holoHC ( P <0.0001) and total HC ( P <0.0001) increased significantly in the vegan population. Only holoHC increased in the population with suspected deficiency ( P <0.0001), whereas no alteration was observed in the nondeficient population. Conclusions: The HC concentration is decreased in severely cobalamin-deficient individuals and increases on treatment. The concentration of cobalamin also relates significantly to the HC concentration in nondeficient individuals.
Victor Herbert - One of the best experts on this subject based on the ideXlab platform.
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Staging vitamin B-12 (cobalamin) status in vegetarians.
The American Journal of Clinical Nutrition, 1994Co-Authors: Victor HerbertAbstract:When one stops eating vitamin B-12 (cobalamins), one passes through four stages of negative cobalamin balance: serum depletion [low holotranscobalamin II, ie, low vitamin B-12 on transcobalamin II (TCII)], cell depletion (decreasing holoHaptocorrin and low red cell vitamin B-12 concentrations), biochemical deficiency (slowed DNA synthesis, elevated serum homocysteine and methylmalonate concentrations), and, finally, clinical deficiency (anemia). Serum vitamin B-12 is on two proteins: the circulating vitamin B-12 delivery protein, TCII, and the circulating vitamin B-12 storage protein, Haptocorrin. Because TCII is depleted of vitamin B-12 within days after absorption stops, the best screening test for early negative vitamin B-12 balance is a measurement of vitamin B-12 on TCII (holoTCII). HoloTCII falls below the bottom of its normal range long before total serum vitamin B-12 (which is mainly vitamin B-12 on Haptocorrin) falls below the bottom of its normal range.
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determination of vitamin b12 cobalamin in serum and erythrocytes by radioassay and of holo transcobalamin ii holo tc ii and holo Haptocorrin holo tc i and iii in serum by adsorbing holo tc ii on microfine silica
Journal of Nutritional Biochemistry, 1991Co-Authors: Cathy Manusselis, Victor HerbertAbstract:Abstract We describe here a competitive inhibition radioassay of vitamin B12 in serum and erythrocytes, including differential radioassays to measure total corrinoids, “true” vitamin B12 (cobalamin), and vitamin B12 analogues in the assay of Lau et al.13 as modified by Kolhouse et al.15, in which the ligands are pure IF and R-binders. We also describe a method to determine holo-TC II (i.e., vitamin B12 on TC II) and holo-Haptocorrin (i.e., vitamin B12 on TC I and TC III) by adsorbing TC II from Haptocorrin (TC I and III) with microfine precipitate of silica (Quso). This procedure adds only one step to the vitamin B12 assay, and delineates negative vitamin B12 balance of patients at a very early stage of developing deficiency, well before the total serum vitamin B12 level falls below the laboratory range of normal.
Dorte L. Lildballe - One of the best experts on this subject based on the ideXlab platform.
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Cobalamin and Haptocorrin in human milk and cobalamin-related variables in mother and child: a 9-mo longitudinal study
The American journal of clinical nutrition, 2013Co-Authors: Eva Greibe, Dorte L. Lildballe, S. Streym, Peter Vestergaard, Lars Rejnmark, Leif Mosekilde, Ebba NexoAbstract:Background: Measurement of milk cobalamin is hampered by the high content of the cobalamin-binding protein Haptocorrin, and limited data are available relating trustworthy measures of milk cobalamin to cobalamin status in healthy mothers and their children. Objectives: The objectives were to explore the concentration of cobalamin and Haptocorrin in foremilk and hindmilk during the first 9 mo of lactation and to relate these results to biomarkers of an impaired cobalamin status of mother and child. Design: Milk samples from 25 mothers were collected at 2 wk, 4 mo, and 9 mo postpartum for the measurement of cobalamin and Haptocorrin. Plasma samples from a larger cohort of lactating mothers (n = 107) and their infants (n = 108) were collected at the same time points for the measurement of cobalamin, holotranscobalamin, total transcobalamin, total Haptocorrin, and methylmalonic acid. Results: Median (range) concentrations of cobalamin in hindmilk were 760 (210‐1880), 290 (140‐690), and 440 (160‐1940) pmol/L at 2 wk, 4 mo, and 9 mo, respectively; the respective Haptocorrin concentrations were 25 (9‐102), 22 (4‐100), and 180 (30‐460) nmol/L. We found slightly lower values in foremilk. A decrease in milk cobalamin at 4 mo was associated with decreases in plasma cobalamin (P , 0.0001) and holotranscobalamin (P , 0.0001) in the infants. Strong positive associations in paired maternal-infant cobalamin concentrations were found at all time points. Conclusions: Foremilk and hindmilk contained comparable amounts of cobalamin and Haptocorrin, but marked changes were observed during 9 mo of lactation. At 4 mo, low concentrations of milk cobalamin mirrored biochemical changes in infants, which suggests an impaired cobalamin status and indicates that nutrition from only mother’s milk may not be sufficient for the supply of cobalamin from this age. This trial was registered by the Danish Data Protection Agency at www.datatilsynet.dk/english as 200841-2185. Am J Clin Nutr doi: 10.3945/ajcn.113.058479.
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Comparison of recombinant human Haptocorrin expressed in human embryonic kidney cells and native Haptocorrin.
PloS one, 2012Co-Authors: Evelyne Furger, Ebba Nexo, Dorte L. Lildballe, Sergey N. Fedosov, Robert Waibel, Roger Schibli, Eliane FischerAbstract:Haptocorrin (HC) is a circulating corrinoid binding protein with unclear function. In contrast to transcobalamin, the other transport protein in blood, HC is heavily glycosylated and binds a variety of cobalamin (Cbl) analogues. HC is present not only in blood but also in various secretions like milk, tears and saliva. No recombinant form of HC has been described so far. We report the expression of recombinant human HC (rhHC) in human embryonic kidney cells. We purified the protein with a yield of 6 mg (90 nmol) per litre of cell culture supernatant. The isolated rhHC behaved as native HC concerning its spectral properties and ability to recognize both Cbl and its baseless analogue cobinamide. Similar to native HC isolated from blood, rhHC bound to the asialoglycoprotein receptor only after removal of terminal sialic acid residues by treatment with neuraminidase. Interestingly, rhHC, that compared to native HC contains four excessive amino acids (…LVPR) at the C-terminus, showed subtle changes in the binding kinetics of Cbl, cobinamide and the fluorescent Cbl conjugate CBC. The recombinant protein has properties very similar to native HC and although showing slightly different ligand binding kinetics, rhHC is valuable for further biochemical and structural studies.
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Association of cognitive impairment with combinations of vitamin B₁₂-related parameters.
Clinical chemistry, 2011Co-Authors: Dorte L. Lildballe, Sergey N. Fedosov, Paul Sherliker, Harold Hin, Robert Clarke, Ebba NexoAbstract:BACKGROUND: Low vitamin B12 concentrations have been associated with higher risks of cognitive impairment, but whether these associations are causal is uncertain. The associations of cognitive impairment with combinations of vitamin B12, holotranscobalamin, methylmalonic acid, and total homocysteine, and with the vitamin B12 transport proteins transcobalamin and Haptocorrin, have not been previously studied. METHODS: We performed a population-based cross-sectional study of 839 people 75 years old or older. We examined the association of cognitive function as measured by mini–mental state examination scores, with markers of vitamin B12 status. Spearman correlations as well as multivariate-adjusted odds ratios and 95% CIs for cognitive impairment were calculated for extreme thirds of serum concentrations of vitamin B12, holotranscobalamin, methylmalonic acid, total homocysteine, combination of these markers in a wellness score, heaptocorrin, and transcobalamin for all data and with B12 analogs in a nested case-control study. RESULTS: Cognitive impairment was significantly associated with low vitamin B12 [odds ratio 2.3 (95% CI 1.2–4.5)]; low holotranscobalamin [4.1 (2.0–8.7)], high methylmalonic acid [3.5 (1.8–7.1)], high homocysteine [4.8 (2.3–10.0)] and low wellness score [5.1 (2.61–10.46)]. After correction for relevant covariates, cognitive impairment remained significantly associated with high homocysteine [4.85 (2.24–10.53)] and with a low wellness score [5.60 (2.61–12.01)] but not with transcobalamin, Haptocorrin, or analogs on Haptocorrin. CONCLUSIONS: Cognitive impairment was associated with the combined effects of the 4 biomarkers of vitamin B12 deficiency when included in a wellness score but was not associated with binding proteins or analogs on Haptocorrin.
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Uptake of cobalamin and markers of cobalamin status: a longitudinal study of healthy pregnant women.
Clinical chemistry and laboratory medicine, 2011Co-Authors: Eva Greibe, Anne L Morkbak, Dorte L. Lildballe, Birgitte Horst Andreasen, Anne-mette Hvas, Ebba NexoAbstract:BACKGROUND Currently, it is unknown whether the decline in plasma cobalamin observed during pregnancy is caused by malabsorption of the vitamin. This study examined cobalamin absorption and markers of cobalamin status during normal pregnancy. METHODS Twenty-seven pregnant Danish women were examined at gestation weeks 13, 24 and 36. The absorption test CobaSorb was performed in all women implying measurement of holotranscobalamin or cyanocobalamin bound to transcobalamin before and after 2 days intake of 3 × 9 μg cobalamin. Serum cobalamin and the two cobalamin binding proteins transcobalamin and Haptocorrin, including Haptocorrin saturated with cobalamin or analogues, were measured, and so was plasma methylmalonic acid and homocysteine. RESULTS No change in the uptake of cobalamin was observed throughout pregnancy. Serum cobalamin displayed a gradual decline during pregnancy (p
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Effect of the vitamin B12-binding protein Haptocorrin present in human milk on a panel of commensal and pathogenic bacteria
BMC research notes, 2011Co-Authors: Henrik R Jensen, Ebba Nexo, Dorte L. Lildballe, Martin Frederik Laursen, Jens Bo Andersen, Tine Rask LichtAbstract:Background: Haptocorrin is a vitamin B12-binding protein present in high amounts in different body fluids including human milk. Haptocorrin has previously been shown to inhibit the growth of specific E. coli strains, and the aim of the present study was to elucidate whether the antibacterial properties of this protein may exert a general defense against pathogens and/or affect the composition of the developing microbiota in the gastrointestinal tracts of breastfed infants. Findings: The present work was the first systematic study of the effect of Haptocorrin on bacterial growth, and included 34 commensal and pathogenic bacteria to which infants are likely to be exposed. Well-diffusion assays addressing antibacterial effects were performed with human milk, Haptocorrin-free human milk, porcine holoHaptocorrin (saturated with B-12) and human apo-Haptocorrin (unsaturated). Human milk inhibited the growth of S. thermophilus and the pathogenic strains L. monocytogenes LO28, L. monocytogenes 4446 and L. monocytogenes 7291, but the inhibition could not be ascribed to Haptocorrin. Human apo-Haptocorrin inhibited the growth of only a single bacterial strain (Bifidobacterium breve), while porcine holo-Haptocorrin did not show any inhibitory effect. Conclusions: Our results suggest that Haptocorrin does not have a general antibacterial activity, and thereby contradict the existing hypothesis implicating such an effect. The study contributes to the knowledge on the potential impact of breastfeeding on the establishment of a healthy microbiota in infants.
