Protein-bound Vitamin Research Articles

Immune-mediated membranous nephropathy: Long term fluconazole usage caused podocyte autophagy.

The primary consequences of membranous nephropathy (MN) are the development of nephrotic syndrome including hypogammaglobulinemia, the increased infectious risk, the loss of protein-bound vitamin D, and, above all, an elevated thromboembolic incidence of up to 50% in severe proteinuria patients. Membrane nephropathy may be either idiopathic or primary, not recognized (70%-80%) or secondary (20%-30%) to pathological sicknesses such as hepatitis B, systemic lupus erythematosus, malignancies, and side-effects of medicines. The immunological responses in MN involvemultiple components: immunoglobulin G (IgG), long-escaped antigens, and the membrane attachment complex, formed by the supplement to form C5b-9. In general, IgG4 is the most significant IgG subclass deposited in idiopathic membranous nephropathic disease but fluctuating IgG1 levels also are linked with immunological deposits. In contrast, IgG1, IgG2, and IgG3 deposition are greater than IgG4 deposition in secondary nephropathy. Fluconazole is a synthetic antifungal triazole that is often used. It is well tolerated in general and hasnever been identified as a cause of nephropathies. We report on the development of MN caused by fluconazole therapy that could potentiate podocyte autophagy.

Characterization of vitamin B12 compounds from marine foods

Vitamin B12 is synthesized by only certain bacteria and archaea but not by animals or plants. In marine environments, bacterial vitamin B12 is transferred and concentrated into fish and shellfish bodies by plankton in the marine food chain. Moreover, marine macrophytic red algae, Porphyra spp. specifically contain substantial amounts of vitamin B12, due to microbial interaction. Although some meats or viscera of edible fish and shellfish are excellent sources of biologically active vitamin B12, an inactive corrinoid, pseudovitamin B12, was found in some edible shellfish using liquid chromatography/electrospray ionization–tandem mass spectrometry. To prevent elderly people from developing vitamin B12 deficiency due to food protein-bound vitamin B12 malabsorption, we present a survey of marine foods containing free vitamin B12. The results of our study suggest that bonito and clam extracts (or soup stocks), which contain considerable amounts of free vitamin B12 are useful not only as seasonings and flavorings but also as excellent sources of free vitamin B12.

Analysis of human cerebrospinal fluid monoamines and their cofactors by HPLC.

The presence of monoamines and their cofactors (the pterins and vitamin B6 (pyridoxal phosphate (PLP))) in human cerebrospinal fluid (CSF) can be used as indicators of the biosynthesis and turnover of dopamine and serotonin in the brain. In addition, abnormalities in the CSF levels of these molecules are associated with various neurological diseases, including genetic diseases leading to dopamine and serotonin deficiency. Here, we provide a set of quantitative high-performance liquid-chromatography (HPLC) approaches to determine CSF levels of monoamines and their cofactors. This protocol describes step-by-step procedures for CSF sample preparation for the analysis of different molecules, HPLC calibration and analysis, and data quantification and interpretation. Unlike plasma/tissue/blood samples, CSF requires minimal sample preparation: in this protocol, only the analysis of PLP requires mixing with trichloroacetic acid to release the protein-bound vitamin, centrifugation, and mixing of the supernatant with phosphate buffer and sodium cyanide for derivatization in alkaline conditions. Monoamines are analyzed by HPLC with coulometric electrochemical detection (ED), pterins are analyzed by HPLC with coupled coulometric electrochemical and fluorescence detection, and PLP is analyzed by HPLC with fluorescence detection. The quantification of all compounds is achieved by external calibration procedures, and internal quality control and standards are analyzed in each run. We anticipate that investigation of dopamine and serotonin disturbances will be facilitated by measurements of these compounds in human CSF and other biological samples. The estimated time for the different procedures primarily depends on the electrochemical detector stabilization. Overnight stabilization of this detector is advised, and, after that step, preanalytical equilibration rarely exceeds 3 h.

Vitamin B12 deficiency and use of acid-suppressive drugs: The association revisited

Vitamin B12 is a water-soluble nutrient involved in several important physiologic processes. Deficiency may lead to a variety of manifestations, such as megaloblastic anemia and neurologic deficits.1 Gastric acid plays a role in vitamin B12 absorption by activating proteolytic enzymes in the stomach, such as pepsin, which free protein-bound vitamin B12 from food sources to make it available for absorption.2,3

Determination of Vitamin B 12 in meat products by RP-HPLC after enrichment and purification on an immunoaffinity column

A quantitative method for the determination of Vitamin B12 in meat products by RP-HPLC and UV detection was developed and compared to the reference method (microbiological assay, MBA). Vitamin B12 was extracted with 50 mM sodium acetate buffer in the presence of sodium cyanide. For the quantification of total Vitamin B12, it was necessary to release protein-bound Vitamin B12 by pepsin treatment. Cyanocobalamin was detected as total Vitamin B12 after purification and enrichment on an immunoaffinity column. The calibration with five concentrations of Vitamin B12 was linear with a regression coefficient r2 > 0.99. The method was validated at three different concentration levels (5–15 ng/g) with salami showing good recovery rates between 80 and 108% and low relative standard deviations between 1.50 and 7.26% (n = 6). The detection limit was found to be 2 ng/g. The Vitamin B12 levels of 50 meat products measured by the developed procedure were similar or significantly lower than those determined by the MBA.

Vitamin B12Deficiency and Depression in the Elderly

Vitamin B₁₂Deficiency and Depression in the Elderly

High dietary cholecalciferol increases plasma 25-hydroxycholecalciferol concentration, but does not attenuate the hypertension of Dahl salt-sensitive rats fed a high salt diet

The Dahl salt-sensitive rat, a model for salt-induced hypertension, develops hypovitaminosis D during high salt intake, which is caused by loss of protein-bound vitamin D metabolites into urine. We tested the hypothesis that high dietary cholecalciferol (5- and 10-fold standard) would increase plasma 25-hydroxycholecalciferol (25-OHD 3) concentration (indicator of vitamin D status) of salt-sensitive rats during high salt intake. Salt-sensitive rats were fed 0.3% salt (low salt, LS), 3% salt (HS), 3% salt and 7.5 μg cholecalciferol/d (HS-D5), or 3% salt and 15 μg cholecalciferol/d (HS-D10) and sacrificed at week 4. Plasma 25-OHD 3 concentrations of the two groups of HS-D rats were similar to that of LS rats and more than twice that of HS rats. Urinary cholecalciferol metabolite content of HS-D rats was more than seven times that of HS rats. Systolic blood pressures of the hypertensive HS and HS-D rats did not significantly differ, whereas LS rats were not hypertensive. We conclude that high dietary cholecalciferol increases plasma 25-OHD 3 concentration, but does not attenuate the hypertension of salt-sensitive rats during high salt intake. Low salt intake may be necessary to both maintain optimal vitamin D status and prevent hypertension in salt-sensitive individuals.

Black and White Female Adolescents Lose Vitamin D Metabolites into Urine

The black American population has a higher prevalence of salt sensitivity compared with the white American population. Dahl salt-sensitive rats, models of salt-induced hypertension, excrete protein-bound vitamin D metabolites into urine, a process that is accelerated during high salt intake. We tested the hypothesis that urinary vitamin D metabolite content and 25-hydroxyvitamin D (25-OHD) binding activity of black female adolescents would be greater than that of white female adolescents. Female adolescents (11-15 years old, 11 black and 10 white) were fed low (1.3 g, 56 mmol/24 hours sodium) and high salt (3.86 g, 168 mmol/24 hours sodium) diets for 3 weeks in a randomized order cross-over study design. White and black adolescents had similar mean urinary vitamin D metabolite content (low salt, black versus white: 50 +/- 10 versus 58 +/- 17 pmol/24 hours; high salt, black versus white: 47 +/- 7 versus 79 +/- 16 pmol/24 hours). Mean urinary 25-OHD binding activities of the black and white adolescents did not significantly differ. Urinary 25-OHD binding activity of 10/11 black adolescents and 7/10 white adolescents was greater at week 3 of high salt intake than at week 3 of low salt intake (r = 0.50, P = 0.002, n = 17). Plasma 24,25-dihydroxyvitamin D concentrations of the white female adolescents were significantly higher than that of the black female adolescents (P < 0.001). Urinary loss of vitamin D metabolites may be one cause of low vitamin D status, in addition to low dietary intake and reduced skin synthesis.

What is an Adequate Dose of Oral Vitamin B&lt;SUB&gt;12&lt;/SUB&gt; in Older People with Poor Vitamin B&lt;SUB&gt;12&lt;/SUB&gt; Status?

The prevalence of vitamin B12 deficiency increases in the elderly, mainly because atrophic gastritis decreases the production of the acid and digestive enzymes needed to cleave protein-bound vitamin B12 from the natural chemical form of vitamin B12 found in meat, poultry, fish, and dairy foods. Depending on the biochemical criterion that is used, 5% to more than 20% of older adults have marginal or frank vitamin B12 deficiency. Adults over 50 years of age should meet the Recommended Dietary Allowance by consuming vitamin B12 in the crystalline form, which does not require gastric acid or enzymes for initial digestion. A recent clinical trial suggests that an oral dose of 500 μg/d of crystalline vitamin B12 is needed to reverse biochemical signs of vitamin B12 deficiency in older adults.

What is an Adequate Dose of Oral Vitamin B12in Older People with Poor Vitamin B12Status?

The prevalence of vitamin B12 deficiency increases in the elderly, mainly because atrophic gastritis decreases the production of the acid and digestive enzymes needed to cleave protein-bound vitamin B12 from the natural chemical form of vitamin B12 found in meat, poultry, fish, and dairy foods. Depending on the biochemical criterion that is used, 5% to more than 20% of older adults have marginal or frank vitamin B12 deficiency. Adults over 50 years of age should meet the Recommended Dietary Allowance by consuming vitamin B12 in the crystalline form, which does not require gastric acid or enzymes for initial digestion. A recent clinical trial suggests that an oral dose of 500 microg/d of crystalline vitamin B12 is needed to reverse biochemical signs of vitamin B12 deficiency in older adults.

Vitamin B12 Deficiency Associated with Histamine2-Receptor Antagonists and a Proton-Pump Inhibitor

OBJECTIVE:To report a case of vitamin B12 deficiency associated with long-term use (∼4½ y) of histamine2 (H2)-receptor antagonists and a proton-pump inhibitor (PPI) in a patient with gastroesophageal reflux.CASE SUMMARY:A 78-year-old nonvegetarian white woman with symptomatic gastroesophageal reflux (GER) was started on cimetidine 300 mg 4 × daily in February 1990 and took various other antisecretory medications over the course of the next 4½ years. She had a normal serum vitamin B12 concentration of 413 pg/mL in August 1992. In June 1994, her serum vitamin B12 concentration was found to be in the low normal range at 256 pg/mL. Biochemical markers of vitamin B12–dependent enzyme activity were measured at that time, and methylmalonic acid (MMA) and homocysteine (HCYS) were elevated at 757 nmol/L and 27.3 μmol/L, respectively. Serum folate was within the normal range at 4.9 ng/mL, and serum creatinine was slightly elevated at 1.4 mg/dL. MMA and HCYS concentrations decreased dramatically with oral replacement of vitamin B12 1000 μg/d, which confirmed vitamin B12 deficiency. Oral replacement also demonstrated that the woman was able to adequately absorb nonprotein—bound vitamin B12 from the gastrointestinal tract, suggesting that her deficiency was a result of food—cobalamin malabsorption. The accumulation of MMA and HCYS was not a consequence of renal dysfunction, since both metabolites dramatically decreased with vitamin B12 replacement.DISCUSSION:Malabsorption of dietary protein-bound vitamin B12 has been demonstrated with the use of H2-receptor antagonists and PPIs. One previous case report of vitamin B12 deficiency resulting from long-term use of omeprazole has been published. The malabsorption of dietary vitamin B12 is thought to be a result of its impaired release from food protein, which requires gastric acid and pepsin as the initial step in the absorption process.CONCLUSIONS:The use of H2-receptor antagonists and/or PPIs may impair the absorption of protein-bound dietary vitamin B12 and could contribute to the development of vitamin B12 deficiency with prolonged use. Patients taking these medications for extended periods of time, particularly >4 years, should be monitored for vitamin B12 status.

Serum biotinidase activity in children with chronic liver disease and its clinical significance.

Biotinidase is the enzyme responsible for liberating the vitamin biotin from biocytin and dietary protein-bound vitamin. Individuals lacking biotinidase activity become biotin deficient. Because the liver is the major source of plasma biotinidase, chronic liver diseases can lead to decreased serum biotinidase activity and biotin deficiency. The aim of this study is to determine serum biotinidase activity values in children with chronic liver disease and to investigate the relation among enzyme activity, certain liver function tests, and degree of liver damage. In this study, using a spectrophotometric method, biotinidase activity was determined in sera from 62 children with chronic liver diseases (median age, 9.73 years; range, 8 months to 18 years) and from 27 healthy controls. Diagnoses of the patient group were as follows: noncirrhotic chronic hepatitis B virus infection (n = 12), metabolic liver diseases (n = 16), autoimmune hepatitis (n = 6), intrahepatic and extrahepatic cholestasis (n = 14), fulminant hepatitis (n = 5), cryptogenic cirrhosis n = 5), prehepatic portal hypertension (n = 4). Meanwhile, serum albumin, total bilirubin, alkaline phosphatase, alanine aminotransferase, and gamma-glutamyltransferase concentrations and prothrombine time were determined for each patient and the results were correlated with serum biotinidase activity. There was significant difference between mean enzyme activity of the controls (7.6 +/- 1.2 nmol x min(-1) x mL(-1)) and of all patients with chronic liver disease (6.3 +/- 2.5 nmol x min(-1) x mL(-1)) ( P < 0.05). Serum biotinidase activity in patients with noncirrhotic chronic liver diseases (chronic viral hepatitis, prehepatic portal hypertension, glycogen storage disease, Gaucher disease) was within the normal ranges. However, serum biotinidase activity in patients with cirrhosis and Wilson disease was significantly less than that of the control group ( P < 0.05). The lowest enzyme activities were detected in patients with fulminant hepatitis. In this study, serum biotinidase activity was significantly lower in patients with cirrhosis, particularly in the patients with decompensated cirrhosis and fulminant hepatitis who exhibited no clinical symptoms related to biotin deficiency. The decreased serum biotinidase activity in chronic liver diseases was associated with severe impairment of hepatocellular function.

Changes in gastric mucosa and luminal environment during acid-suppressive therapy: a review in depth.

Acid-suppressive therapy and subsequent changes in gastric mucosa and luminal environment rank highly amongst the investigated issues in gastroenterology over the past two to three decades. Herewith, we present an overview of these intragastric changes, particularly during long-term administration of acid-suppresive medication and concurrent infection with Helicobacter pylori. Current evidence indicates that: i) Long-term acid suppression facilitates the development of fundic ECL cell hyperplasia, especially in the presence of Helicobacter pylori. No neoplastic changes directly attributable to acid suppression have so far been demonstrated in humans. ii) Acid-suppressive therapy increases the risk of enteric infections. iii) Acid-suppressive therapy does not alter fat and mineral bioavailability, but may decrease the absorption of protein-bound vitamin B12. iv) Acid suppression invariably results in intragastric overgrowth of non-Helicobacter pylori bacterial species. The concurrent infection with Helicobacter pylori may promote this bacterial overgrowth and the intragastric formation of N-nitrosamines. v) Acid-suppressive therapy alters the natural course of Helicobacter pylori gastritis, transforming the antral-predominant pattern into a body-predominant pattern, which in turn may progress to body gland atrophy. The pathophysiology of this phenomenon is currently under investigation. vi) In view of the potential adverse effects of acid suppression in the presence of Helicobacter pylori, the screen-and-treat strategy is advocated for Helicobacter pylori in subjects considered for long-term treatment.

Vitamin B12 deficiency in the elderly.

Vitamin B12 deficiency is estimated to affect 10%-15% of people over the age of 60, and the laboratory diagnosis is usually based on low serum vitamin B12 levels or elevated serum methylmalonic acid and homocysteine levels. Although elderly people with low vitamin B12 status frequently lack the classical signs and symptoms of vitamin B12 deficiency, e.g. megaloblastic anemia, precise evaluation and treatment in this population is important. Absorption of crystalline vitamin B12 does not decline with advancing age. However, compared with the younger population, absorption of protein-bound vitamin B12 is decreased in the elderly, owing to a high prevalence of atrophic gastritis in this age group. Atrophic gastritis results in a low acid-pepsin secretion by the gastric mucosa, which in turn results in a reduced release of free vitamin B12 from food proteins. Furthermore, hypochlorhydria in atrophic gastritis results in bacterial overgrowth of the stomach and small intestine, and these bacteria may bind vitamin B12 for their own use. The ability to absorb crystalline vitamin B12 remains intact in older people with atrophic gastritis. The 1998 recommended daily allowance for vitamin B12 is 2.4 micrograms, but elderly people should try to obtain their vitamin B12 from either supplements or fortified foods (e.g. fortified ready-to-eat breakfast cereals) to ensure adequate absorption from the gastrointestinal tract. Because the American food supply is now being fortified with folic acid, concern is increasing about neurologic exacerbation in individuals with marginal vitamin B12 status and high-dose folate intake.

Practitioners’ Guide to Meeting the Vitamin B-12 Recommended Dietary Allowance for People Aged 51 Years and Older

In response to research findings that 10% to 30% of people aged 51 years and older may have protein-bound vitamin B-12 malabsorption, the National Academy of Sciences’ Institute of Medicine recommends that these people consume a majority of the new Recommended Dietary Allowance (RDA) of 2.4 μg/day in its synthetic form rather than in its food form. Protein-bound vitamin B-12 malabsorption in older adults has been attributed to reduced pepsin activity and gastric acid secretion, which interfere with cleavage of vitamin B-12 from dietary protein before absorption. Unlike patients with pernicious anemia, most people with protein-bound vitamin B-12 malabsorption produce intrinsic factor and have the ability to absorb synthetic vitamin B-12 normally. Early diagnosis is necessary to prevent the untoward effects of vitamin B-12 deficiency. A thorough assessment of vitamin B-12 status entails measurement of multiple biochemical assessment indexes, including serum vitamin B-12, methylmalonic acid, and homocysteine concentrations. Dietitians and other health care professionals should be aware of the prevalence of vitamin B-12 deficiency in older adults and be familiar with sources of synthetic vitamin B-12 to facilitate implementation of the new RDA. J Am Diet Assoc. 1999;99:725-727.

Gastric Hypochlorhydria and Achlorhydria in Older Adults-Reply

The studies by Dr Russell and colleagues have added to our appreciation that achlorhydria, resulting from either omeprazole administration or atrophic gastritis, can cause malabsorption of protein-bound vitamin B 12 . 1 Though we did not determine absorption or levels of vitamin B 12 , we do not share his view that our data show one third of elderly Americans to be at risk of malabsorption of food-bound vitamin B 12 . Six (2%) of our 248 subjects were receiving vitamin B 12 injections, 4 of whom had low basal acidity by the resin test (urine quinine

Vitamin B-12 deficiency after gastric surgery for obesity

Low serum vitamin B-12 concentrations after gastric bypass (GB) surgery for obesity were observed in 11 of 28 patients without detectable impairment of crystalline vitamin B-12 absorption. This was observed in 2 of 19 patients with vertical banded gastroplasty (VBG). In contrast, protein-bound vitamin B-12 absorption was markedly impaired, as demonstrated in eight of these patients after GB (n = 7) and VBG (n = 1). Correction of this impaired absorption occurred when protein-bound vitamin B-12 was incubated with an enzyme mixture before consumption. Simultaneous ingestion of the enzyme mixture with protein-bound vitamin B-12 did not improve absorption of the vitamin. In a separate experiment, 10 patients with a normal result from the Schilling test failed to correct low serum vitamin B-12 concentrations with a quantity of oral crystalline vitamin B-12 equal to the recommended dietary allowance of 2 micrograms, taken twice daily for 3 mo. Serum total homocysteine values declined during this interval. An oral daily dose of 350 micrograms crystalline vitamin B-12 raised the average serum vitamin B-12 concentration to an amount greater than the lower reference limit. A dose > 350 micrograms/d was required to raise all patients' vitamin B-12 concentrations above this concentration rather than just above the population mean. We conclude that because concentrations of oral crystalline vitamin B-12 were required to normalize serum vitamin B-12 concentrations, that a mechanism other than formation of a vitamin B-12 intrinsic factor complex is responsible for crystalline vitamin B-12 absorption after GB for obesity.

12 Cobalamin and folate deficiency in the elderly

Elderly persons are more likely to have low values for serum and erythrocyte folate, and for serum cobalamin. Many of those with low vitamin levels have biochemical abnormalities consistent with true deficiency, including increased formiminoglutamic acid excretion, abnormal marrow deoxyuridine suppression, and raised serum levels of methylmalonic acid and homocysteine. Therapy with the appropriate vitamin reverses the biochemical defect. Despite this, the clinical consequences for most elderly persons are remarkably few. True megaloblastic anaemia is rare, and the small number of therapeutic trials to date have not improved the levels of haemoglobin in the treated subjects, although the mean corpuscular volume has decreased significantly. There has been recent concern that these low blood vitamin levels might be important causes of nervous system damage, but studies specifically of the elderly have not demonstrated overall improvements in neurological function following therapy. Vascular damage from high blood homocysteine levels secondary to cobalamin or folate deficiency remains a potential hazard. Dietary insufficiency, malabsorption of protein-bound vitamin B12 secondary to atrophic gastritis, and defective absorption of folyl polyglutamates seem the likeliest possible causes. Pernicious anaemia, although a common cause of severe megaloblastic anaemia in the elderly, is an infrequent cause for the low cobalamin levels in population studies. Although the benefits are uncertain, the balance of the evidence suggests that one should treat elderly persons with low values of cobalamin or folate. Crystalline vitamin B12 and folic acid are absorbed normally and are therefore suitable for replacement therapy, provided that pernicious anaemia is excluded.

Detection of Protein Bound Vitamin B12 Malabsorption

The Schilling test is used to identify the cause of vitamin B12 malabsorption in patients with low serum vitamin B12 levels. The initial step required for vitamin B12 absorption is a process of separation from the protein complexes of food. The crystalline Co-57 vitamin B12 used in the Schilling test does not reproduce this physiologic process. Thus, a crystalline stage I Schilling test may be normal even in the face of cobalamin malabsorption. An adjunctive stage I Schilling test using Co-57 vitamin B12 bound to protein has been developed. The authors describe a patient with protein-bound vitamin B12 malabsorption whose crystalline Co-57 vitamin B12 stage I Schilling test was normal. A subsequent stage I Schilling test using Co-57 vitamin B12 bound to chicken serum revealed significant cobalamin malabsorption. A review of the history and literature of this diagnostic test using protein bound vitamin B12 is also presented.

Letters: Omeprazole and Vitamin B_12

Letters1 July 1994Letters: Omeprazole and Vitamin B12Stefan P. Marcuard, MDStefan P. Marcuard, MDEast Carolina University School of Medicine; Greenville, NC 27858-4354Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-121-1-199407010-00022 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail IN RESPONSE:Our study design to evaluate protein-bound B12 absorption before and during treatment with omeprazole is appropriate and is known as “self-pairing” [1, 2]. This method eliminates the variability between study patients and “controls.” Although we agree that a placebo group would have strengthened our results, our straightforward study design is adequate to show changes in vitamin B12 absorption during omeprazole therapy.Dr. Lavy's comments indicate a misunderstanding of vitamin B12 digestion and absorption. To correct protein-bound vitamin B12 malabsorption, hydrochloric acid (not vitamin B12) is added to the modified Schilling tests. In fact, this has been done by ...