Current concepts in cobalamin deficiency

Crystal structure of l-threonine-O-3-phosphate decarboxylase CobC from Sinorhizobium meliloti involved in vitamin B12 biosynthesis

Vitamin B12 is involved in many important biochemical reactions for humans, and its deficiency can lead to serious diseases. The industrial production of vitamin B12 is achieved through microbial fermentation. In this work, we determine the crystal structures of the l-threonine-O-3-phosphate (Thr-P) decarboxylase CobC from Sinorhizobium meliloti (SmCobC), an industrial vitamin B12-producing bacterium, in apo form and in complex with a reaction intermediate. Our structures supported the Thr-P decarboxylase activity of SmCobC and revealed that the positively charged substrate-binding pocket between the large and small domains determines its substrate selectivity for Thr-P. Moreover, our results provided evidence for the proposition that the AP-P linker is formed by direct incorporation of AP-P in the biosynthetic pathway of vitamin B12 in S.meliloti.

Crystal structure of methyltransferase CbiL from Akkermansia muciniphila

Akkermansia muciniphila is a mucin-degrading probiotic that colonizes the gastrointestinal tract. Genomic analysis identified a set of genes involved in the biosynthesis of corrin ring, including the cobalt factor II methyltransferase CbiL, in some phylogroups of A. muciniphila, implying a potential capacity for de novo synthesis of cobalamin. In this work, we determined the crystal structure of CbiL from A. muciniphila at 2.3 Å resolution. AmCbiL exists as a dimer both in solution and in crystal, and each protomer consists of two α/β domains, the N-terminal domain and the C-terminal domain, consistent with the folding of typical class III MTases. The two domains create an open trough, potentially available to bind the substrates SAM and cobalt factor II. Sequence and structural comparisons with other CbiLs, assisted by computer modeling, suggest that AmCbiL should have cobalt factor II C-20 methyltransferase activity. Our results support that certain strains of A. muciniphila may be capable of synthesizing cobalamin de novo.

Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta-analysis

BACKGROUND

This systematic review and network meta-analysis aimed to evaluate the three different administration routes of vitamin B12: oral, intramuscular (IM), and sublingual (SL) routes.

METHODS

We searched four electronic databases (PubMed, Scopus, Web of Science, and Cochrane CENTRAL Register of Controlled Trials). We included only comparative studies. We performed a frequentist network meta-analysis to measure network estimates for the relative outcomes. Moreover, we conducted a pairwise meta-analysis using a random effect model to obtain direct estimates for outcomes. All outcomes were continuous, and the relative treatment effects were pooled as mean difference (MD) with 95% confidence intervals.

RESULTS

Thirteen studies were included in the meta-analysis, with a total of 4275 patients. Regarding increasing vitamin B12 levels, the IM route ranked first, followed by the SL route (MD = 94.09 and 43.31 pg/mL, respectively) compared to the oral route. However, these differences did not reach statistical significance owing to the limited number of studies. Regarding the hemoglobin level, the pooled effect sizes showed no difference between all routes of administration that could reach statistical significance. However, the top two ranked administration routes were the oral route (78.3) and the IM route (49.6).

CONCLUSION

All IM, oral, and SL routes of administration of vitamin B12 can effectively increase the level of vitamin B12 without significant differences between them, as thought previously. However, the IM route was the top-ranked statistically but without clinical significance. We found no significant difference among studied administrated routes in all other CBC parameters and homocysteine levels.

Exploring the Impact of Cigarette Smoke Extracts on Vitamin B12: Insights into the Transformation of Methylcobalamin and Hydroxycobalamin to Cyanocobalamin through In Vitro Evaluation

Vitamin B12 (cobalamin) is a water-soluble molecule required for the proper functioning of metabolism, blood and DNA synthesis, and neurological development. Vitamin B12 exists in several forms: methylcobalamin (MeCbl), adenosylcobalamin (AdoCbl), hydroxycobalamin (OHCbl), and cyanocobalamin (CNCbl). This study aimed to evaluate the effect of cigarette smoke on the chemical structure of methylcobalamin and hydroxycobalamin forms of vitamin B12. MeCbl and OHCbl were markedly affected by exposure to cigarette smoke. The resemblance of the Rt between MeCbl and OHCbl and CNCbl indicates that exposure to cigarette smoke extracts chemically alters MeCbl and OHCbl to CNCbl, warranting in vivo research investigations.

The Epidemiology of Deficiency of Vitamin B12 in Preschool Children in Turkey

Background: Vitamin B12 is a water-soluble vitamin with important cellular functions; it is an essential vitamin. The aim of this study is to determine the B12 levels of children in the period from the 6th month when they start taking additional foods to the age of seven (preschool children) and the risk factors affecting them. Methods: One hundred pediatric patients aged 6-72 months who were diagnosed with vitamin B12 deficiency and their parents who agreed to attend Istanbul Atlas University, Medical Faculty, "Medicine Hospital" Pediatric Clinic between September 2022 and June 2023 were prospectively included in this study. Results: B12 deficiency was significantly higher in the 6-11 (25%)-month group than in the 12-23 (5.8%)- and 24-47 (2.8%)-month groups. Homocysteine levels were highest in those with insufficient B12 levels compared to the other groups. There was no statistically significant difference in weekly dairy and meat consumption levels between age groups. B12 levels were lower in the 6-11-month group than in the other groups. Homocysteine levels were highest in those with insufficient B12 levels (<200 pg/mL (148 pmol/L)). Folic acid levels were lower in the 24-47-month and 48-72-month groups than in the 6-11-month and 12-23-month groups. Conclusions: The results obtained in this study showed that low vitamin B12 and increased homocysteine levels seem to be important risk factors in preschool children, especially from the 6th month when they start consuming additional foods. The diagnosis of B12 deficiency can be confirmed by elevated serum total homocysteine levels, which are evidence of functional cobalamin deficiency.

Nutritional Neuropathies

OBJECTIVE

This article reviews the etiologies, presentations, and management of neuropathies related to nutritional deficiencies.

LATEST DEVELOPMENTS

Peripheral neuropathy can be the predominant or only manifestation of certain nutrient deficiencies. Cognitive difficulties or involvement of other parts of the central nervous system, such as the optic nerve and spinal cord, may accompany nutritional peripheral neuropathies. In most patients, the nutritional deficiency may have a single predominant cause, but in some cases, multiple causes may coexist. Obesity, for unclear reasons, can be associated with nutrient deficiencies. The rising rates of bariatric surgery and the incidence of nutrient deficiencies following bariatric surgery make this a particularly relevant topic for neurologists.

ESSENTIAL POINTS

Neuropathies caused by nutrient deficiencies are preventable with appropriate supplementation in high-risk situations. Early recognition and prompt treatment are essential to ensure an optimal outcome and minimize neurologic morbidity.

Effects of vitamin B12 deficiency on risk and outcome of ischemic stroke

Ischemic stroke is the most prevalent form of stroke and has a high incidence in older adults, characterized by high morbidity, mortality, disability, and recurrence rate. Vitamin B₁₂ deficiency is prevalent in the elderly and has been reported to be associated with ischemic stroke. The mechanisms maybe include the disorder of methylation metabolism, accumulation of toxic metabolites, immune dysfunction, affecting gut microbial composition and gut-brain immune homeostasis, and toxic stress responses to the brain. Vitamin B₁₂ deficiency may lead to cerebral artery atherosclerosis, change myelination, influence the metabolism and transmission between nerve tissue, and ultimately causes the occurrence and development of ischemic stroke. This paper reviews the correlation between vitamin B₁₂ deficiency and ischemic stroke, looking forward to improving clinicians' understanding and providing new therapeutic directions for ischemic stroke.

Vitamin B12 deficiency presenting with a pancytopenia in pregnancy

Vitamin B12 deficiency is a significant public health problem globally. Although it is a well-known cause of macrocytic anaemia and in advanced cases, pancytopenia, there remains a relative paucity of cases reported in pregnancy. It is associated with an increased risk of pregnancy complications and adverse birth outcomes such as neural tube defects, preterm birth, low birth weight, neurological sequelae and intrauterine death. It has a predilection for individuals aged >60 years. It has been implicated in a spectrum of neuropsychiatric disorders and it may also exert indirect cardiovascular effects. Severe vitamin B12 deficiency may present with haematological abnormalities that mimic thrombotic microangiopathy such as HELLP syndrome (haemolysis, elevated liver enzymes and low platelets) or it may present as pseudothrombotic microangiopathy (Moschcowitz syndrome) characterised by anaemia, thrombocytopenia and schistocytosis. It can also closely mimic thrombotic thrombocytopenia purpura, hence posing a diagnostic challenge to the unwary physician. Serological measurement of vitamin B12 levels confirms the diagnosis. Oral supplementation with vitamin B12 remains a safe and effective treatment. The authors describe the case of a multiparous woman in her late 20s presenting with a plethora of non-specific symptoms at 29+5 weeks' gestation. Her haemoglobin was 45 g/L, platelets 32×109/L, vitamin B12 <150 ng/L and serum folate <2 µg/L. She was not a vegetarian, but her diet lacked nutrition. Following parenteral B12 supplementation, her haematological parameters improved. The pregnancy was carried to term. Due to the plethora of non-specific symptoms, the diagnosis can be challenging to establish. Adverse maternal or fetal outcomes may occur. Folic acid supplementation may mask an occult vitamin B12 deficiency and further exacerbate or initiate neurological disease.

Comparison of Serum Holotranscobalamin with Serum Vitamin B12 in Population Prone to Megaloblastic Anemia and their Correlation with Nerve Conduction Study

Early detection of megaloblastic anemia and associated neurological complications is crucial for management. This study was conducted to compare serum holotranscobalamin level with serum vitamin B12 level as early biomarker in people prone to megaloblastic anemia and to evaluate co-relation between these biomarkers and nerve conduction study in study patients. 83 adult patients (Hb > 12 gm/dl) prone to megaloblastic anemia were studied for basic haematological investigations, random blood sugar, thyroid function test, liver function test, kidney function test, serum vitamin B12, serum holotranscobalamin and serum folic acid levels. 45 patients among them underwent nerve conduction studies. All study patients were classified in 6 groups on the basis of risk factors for megaloblastic anemia. 29 patients (34.9%) were on antiepileptic drugs, 26 (31.3%) were chronic alcoholic, 10 patients (12%) each, had malabsorption and ileal tuberculosis, 6 (7.22%) had chronic pancreatitis and 2 (2.4%) had ileal resection. 30 patients (36.14%) had low serum holotranscobalamin, including 7 patients (8.43%) with low serum vitamin B12 level also, unmasking vitamin B12 deficiency in 23 patients (27.7%). 7 patients (8.43%) had mean corpuscular volume (MCV) > 100fL and 8 patients (9.63%) had vitamin B12 deficiency related changes on peripheral smear. Serum vitamin B12 and holotranscobalamin levels were significantly low in patients with peripheral smear changes, with p value 0.039 and 0.041 respectively, while no such association seen with MCV. Subclinical peripheral neuropathy was detected in 18 (40%) out of 45 patients on nerve conduction study. Serum holotranscobalamin levels were significantly lower (p = 0.031) than serum vitamin B12 levels (p = 0.2) in patients with neuropathic changes. Rest investigations and serum folic acid levels were normal in all patients. Holotranscobalamin levels can be considered early and reliable marker for vitamin B12 deficiency and deficiency associated peripheral neuropathy, even in patients who are prone to megaloblastic anemia, and not yet anemic or symptomatic for neuropathy.

Serum cobalamin concentrations in dogs infected with canine parvoviral enteritis

OBJECTIVE

To compare the serum cobalamin concentrations in canine parvovirus (CPV)-infected dogs with those of healthy control dogs.

Animals

45 dogs with CPV enteritis and 17 healthy age-matched control dogs.

Procedures

Infection was confirmed by visualization of CPV-2 through fecal electron microscopy. All dogs received supportive care. Serum samples taken at admission were used to determine cobalamin, C-reactive protein, and albumin concentrations.

Results

Serum cobalamin concentrations were significantly lower in the CPV-infected group (median [interquartile range], 173 pmol/L [< 111 to 722 pmol/L]) than in healthy control dogs (379 pmol/L [193 to > 738 pmol/L). There was no association between cobalamin concentration and C-reactive protein or albumin concentration.

Clinical Relevance

While hypocobalaminemia was common in CPV-infected dogs, the clinical relevance of this finding remains to be determined. Studies assessing markers of cellular cobalamin deficiency in dogs with CPV infection appear warranted.

Dietary Intake and Status of Vitamin B12 in Slovenian Population

Vitamin B12 deficiency poses a health concern, especially in vulnerable populations. Dietary vitamin B12 intake was obtained by two 24 h dietary recalls and food propensity questionnaires in a representative Slovenian cross-sectional food consumption survey, SI.Menu (n = 1248 subjects; 10-74 years). For a subgroup of 280 participants, data on serum vitamin B12 were available through the Nutrihealth study. The estimated usual population-weighted mean daily vitamin B12 intakes were 6.2 µg (adults), 5.4 µg (adolescents), and 5.0 µg (elderly). Lower intakes were observed in females. Inadequate daily vitamin B12 intake (<4 µg) was detected in 37.3% of adolescents, 31.7% of adults, and 58.3% elderlies. The significant predictors for inadequate daily vitamin B12 intake were physical activity score in all age groups, sex in adolescents and adults, financial status and smoking in elderly, and employment in adults. Meat (products), followed by milk (products), made the highest vitamin B12 contribution in all age groups. In adolescents, another important vitamin B12 contributor was cereals. The mean population-weighted serum vitamin B12 levels were 322.1 pmol/L (adults) and 287.3 pmol/L (elderly). Low serum vitamin B12 concentration (<148 nmol/L) and high serum homocysteine (>15 µmol/L) were used as criteria for vitamin B12 deficiency. The highest deficiency prevalence was found in elderlies (7.0%), particularly in males (7.9%). Factors associated with high serum homocysteine were also investigated. In conclusion, although vitamin B12 status was generally not critical, additional attention should be focused particularly to the elderly.

Nitrous oxide-related neurological disorders: Clinical, laboratory, neuroimaging, and electrophysiological findings

BACKGROUND

Recreational N₂ O abuse is an important etiology of neurological impairment in young patients, which may easily be ignored clinically. Few current studies have investigated the characteristics or the effects experienced by its users. We aimed to explore any correlation between the clinical severity and biomarkers and spinal magnetic resonance imaging (MRI) abnormalities, identify independent factors associated with spinal MRI abnormalities, and ascertain factors affecting depression/anxiety in patients with N₂ O-related neurological disorders.

METHODS

Patients with N₂ O-related neurological disorders were enrolled retrospectively between February 2017 and July 2020. Their demographic, clinical, laboratory, neuroimaging, electrophysiological, and neuropsychological findings were analyzed. Correlation analyses were conducted using Spearman's or Pearson's correlation and linear regression analysis. Independent factors associated with spinal MRI abnormalities were identified using univariate and multivariate analyses.

RESULTS

The principal clinical manifestations of N₂ O-related neurological disorders (n = 63; 38 men, 25 women; mean age ± SD: 22.60 ± 4.46 years) were sensory disturbance, followed by gait disturbance and pyramidal tract damage. A significant negative correlation existed between serum vitamin B₁₂ levels and clinical severity (r = -0.309, p = .014), which disappeared after linear regression. An interval of less than 6 months between initial N₂ O abuse and hospitalization was independently associated with spinal MRI abnormalities (39.47% vs. 72.00%, respectively; χ²  = 6.40, p = .01). Thirty-eight (60.32%) and 40 (63.49%) patients experienced anxiety and depression, respectively. Moreover, the higher the clinical scores/serum homocysteine levels, the greater the severity of anxiety/depression (r = 0.442, p < .01; r = 0.346, p < .01; r = 0.477, p < .01; r = 0.324, p < .01).

CONCLUSIONS

The significant inverse correlation between initial vitamin B₁₂ levels and clinical severity could aid prognosis prediction in patients with N₂ O-related neurological disorders. Spinal MRI abnormalities were not related to clinical severity but depended on the time interval between initial N₂ O abuse and hospitalization. Anxiety and depression were common comorbidity in these patients, and their severity increased with the intensity of clinical impairment and/or serum homocysteine levels.

Pseudothrombotic Microangiopathy as a Rare Presentation of Cobalamin Deficiency

The hematological manifestations of cobalamin (vitamin B12) deficiency may range from asymptomatic to life-threatening forms. Pseudothrombotic microangiopathy is a rare but severe presentation, characterized by the presence of hemolysis and schistocytosis, that is completely reversible after vitamin supplementation.

We present a challenging diagnostic approach of a 55-year-old man who presented with high hemolytic markers, pancytopenia, and schistocytes on the peripheral smear due to acquired cobalamin deficiency. Subsequent testing revealed positive anti-intrinsic factor and anti-parietal cell antibodies consistent with pernicious anemia. Cobalamin replacement led to the resolution of microangiopathic hemolysis and clinical improvement, thereby confirming the diagnosis.

This case highlights the importance of early recognition of this syndrome, which is often misdiagnosed as true microangiopathic hemolytic anemia, confounding appropriate management.

Long-term metformin therapy and vitamin B12 deficiency: An association to bear in mind

To date, metformin remains the first-line oral glucose-lowering drug used for the treatment of type 2 diabetes thanks to its well-established long-term safety and efficacy profile. Indeed, metformin is the most widely used oral insulin-sensitizing agent, being prescribed to more than 100 million people worldwide, including patients with prediabetes, insulin resistance, and polycystic ovary syndrome. However, over the last decades several observational studies and meta-analyses have reported a significant association between long-term metformin therapy and an increased prevalence of vitamin B12 deficiency. Of note, evidence suggests that long-term and high-dose metformin therapy impairs vitamin B12 status. Vitamin B12 (also referred to as cobalamin) is a water-soluble vitamin that is mainly obtained from animal-sourced foods. At the cellular level, vitamin B12 acts as a cofactor for enzymes that play a critical role in DNA synthesis and neuroprotection. Thus, vitamin B12 deficiency can lead to a number of clinical consequences that include hematologic abnormalities (e.g., megaloblastic anemia and formation of hypersegmented neutrophils), progressive axonal demyelination and peripheral neuropathy. Nevertheless, no definite guidelines are currently available for vitamin B12 deficiency screening in patients on metformin therapy, and vitamin B12 deficiency remains frequently unrecognized in such individuals. Therefore, in this "field of vision" article we propose a list of criteria for a cost-effective vitamin B12 deficiency screening in metformin-treated patients, which could serve as a practical guide for identifying individuals at high risk for this condition. Moreover, we discuss additional relevant topics related to this field, including: (1) The lack of consensus about the exact definition of vitamin B12 deficiency; (2) The definition of reliable biomarkers of vitamin B12 status; (3) Causes of vitamin B12 deficiency other than metformin therapy that should be identified promptly in metformin-treated patients for a proper differential diagnosis; and (4) Potential pathophysiological mechanisms underlying metformin-induced vitamin B12 deficiency. Finally, we briefly review basic concepts related to vitamin B12 supplementation for the treatment of vitamin B12 deficiency, particularly when this condition is induced by metformin.

Vitamin B12 status in health and disease: a critical review. Diagnosis of deficiency and insufficiency - clinical and laboratory pitfalls

Vitamin B₁₂ (cobalamin) is an essential cofactor for two metabolic pathways. It is obtained principally from food of animal origin. Cobalamin becomes bioavailable through a series of steps pertaining to its release from dietary protein, intrinsic factor-mediated absorption, haptocorrin or transcobalamin-mediated transport, cellular uptake, and two enzymatic conversions (via methionine synthase and methylmalonyl-CoA-mutase) into cofactor forms: methylcobalamin and adenosylcobalamin. Vitamin B₁₂ deficiency can masquerade as a multitude of illnesses, presenting different perspectives from the point of view of the hematologist, neurologist, gastroenterologist, general physician, or dietician. Increased physician vigilance and heightened patient awareness often account for its early presentation, and testing sometimes occurs during a phase of vitamin B₁₂ insufficiency before the main onset of the disease. The chosen test often depends on its availability rather than on the diagnostic performance and sensitivity to irrelevant factors interfering with vitamin B₁₂ markers. Although serum B₁₂ is still the most commonly used and widely available test, diagnostics by holotranscobalamin, serum methylmalonic acid, and plasma homocysteine measurements have grown in the last several years in routine practice. The lack of a robust absorption test, coupled with compromised sensitivity and specificity of other tests (intrinsic factor and gastric parietal cell antibodies), hinders determination of the cause for depleted B₁₂ status. This can lead to incorrect supplementation regimes and uncertainty regarding later treatment. This review discusses currently available knowledge on vitamin B₁₂, informs the reader about the pitfalls of tests for assessing its deficiency, reviews B₁₂ status in various populations at different disease stages, and provides recommendations for interpretation, treatment, and associated risks. Future directions for diagnostics of B₁₂ status and health interventions are also discussed.

Antivitamins B12 -Some Inaugural Milestones

The recently delineated structure- and reactivity-based concept of antivitamins B12 has begun to bear fruit by the generation, and study, of a range of such B12 -dummies, either vitamin B12 -derived, or transition metal analogues that also represent potential antivitamins B12 or specific B12 -antimetabolites. As reviewed here, this has opened up new research avenues in organometallic B12 -chemistry and bioinorganic coordination chemistry. Exploratory studies with antivitamins B12 have, furthermore, revealed some of their potential, as pharmacologically interesting compounds, for inducing B12 -deficiency in a range of organisms, from hospital resistant bacteria to laboratory mice. The derived capacity of antivitamins B12 to induce functional B12 -deficiency in mammalian cells and organs also suggest their valuable potential as growth inhibitors of cancerous human and animal cells.

Post-Liver Transplantation Anemia and Its Correlation with Mortality and Graft Failure

BACKGROUND

In adults, post-liver transplantation anemia (PLTA) is common, but its characteristics and long-term influence on major outcomes have yet to be elucidated.

AIM

We aimed to assess prevalence, characteristics, predictors, and outcomes of PLTA at 6 months (early PLTA) and at 2 years (late PLTA).

METHODS

A single-center retrospective cohort study using prospectively collected data from liver transplantations in adults during January 2007-December 2015. PLTA impact on various long-term outcomes was assessed, including mortality, composites of mortality or graft failure, cardiovascular outcomes, and malignancy occurrences.

RESULTS

Hundred and fifty liver transplanted individuals were included. There was a 79% prevalence of anemia pre-transplantation, whereas early and late PLTA were evident in 58% and 40% of patients, respectively. Pre-transplantation anemia was associated with development of early PLTA which was associated with late PLTA. In a multivariate analysis, early PLTA was significantly associated with mortality or graft failure at a follow-up of 3 years (odds ratio 3.838, 95% CI 1.114-13.226). Late PLTA was not significantly associated with worse long-term outcomes.

CONCLUSIONS

Early and late PLTA are prevalent among liver transplanted patients. Early PLTA is associated with long-term mortality or graft failure.

Elevated Plasma Vitamin B12 in Patients with Hepatic Glycogen Storage Diseases

Background: Hepatic glycogen storage diseases (GSDs) are inborn errors of metabolism affecting the synthesis or breakdown of glycogen in the liver. This study, for the first time, systematically assessed vitamin B₁₂ status in a large cohort of hepatic GSD patients. Methods: Plasma vitamin B₁₂, total plasma homocysteine (tHcy) and methylmalonic acid concentrations were measured in 44 patients with hepatic GSDs and compared to 42 healthy age- and gender-matched controls. Correlations of vitamin B₁₂ status with different disease markers of GSDs (including liver transaminase activities and triglycerides) as well as the vitamin B₁₂ intake were studied. Results: GSD patients had significantly higher plasma vitamin B₁₂ concentrations than healthy controls (p = 0.0002). Plasma vitamin B₁₂ concentration remained elevated in GSD patients irrespective of vitamin B₁₂ intake. Plasma vitamin B₁₂ concentrations correlated negatively with triglyceride levels, whereas no correlations were detected with liver transaminase activities (GOT and GPT) in GSD patients. Merging biomarker data of healthy controls and GSD patients showed a positive correlation between vitamin B₁₂ status and liver function, which suggests complex biomarker associations. A combined analysis of biomarkers permitted a reliable clustering of healthy controls versus GSD patients. Conclusions: Elevated plasma concentration of vitamin B₁₂ (irrespective of B₁₂ intake) is a common finding in patients with hepatic GSD. The negative correlation of plasma vitamin B₁₂ with triglyceride levels suggests an influence of metabolic control on the vitamin B₁₂ status of GSD patients. Elevated vitamin B₁₂ was not correlated with GOT and GPT in our cohort of GSD patients. Merging of data from healthy controls and GSD patients yielded positive correlations between these biomarkers. This apparent dichotomy highlights the intrinsic complexity of biomarker associations and argues against generalizations of liver disease and elevated vitamin B₁₂ in blood. Further studies are needed to determine whether the identified associations are causal or coincidental, and the possible impact of chronically elevated vitamin B₁₂ on GSD.

Assessing Diagnostic Accuracy of Serum Holotranscobalamin (Active-B12) in Comparison with Other Markers of Vitamin B12 Deficiency

About 15-40% India is Vitamin B12 deficient (commonly diagnosed by total Vitamin B12) but, as only holoTC (active form) is taken up by body cells, thus measuring holoTC is more reflective of Vitamin B12 status than the former. We aimed to assess diagnostic accuracy of serum holoTC in comparison with total Vitamin B12 and total Homocysteine (HCY) as indicator of serum Vitamin B12 status. 217 human subjects (99 males and 118 females) ranging from 17 to 83 years were divided into Vitamin B12 deficient (n = 70), borderline (n = 100) and sufficient groups (n = 47) who were further assessed for markers of Vitamin B12 deficiency-holoTC, HCY, Mean Corpuscular Volume (MCV), Folate, heamoglobin and creatinine. Samples were analysed using Siemens Advia Centaur Xpi. Total Vitamin B12 deficient group had - 84.3% holoTC deficient; 15.7% holoTC sufficient; 72.9% with elevated HCY; 27.1% with normal HCY; 11.4% with megaloblastic anaemia. Borderline group had - 34% holoTC deficient; 28% elevated HCY. A strong positive correlation was found between Total Vitamin B12 and holoTC (r = 0.754, p = <0.001) but strong negative correlation existed between holoTC and HCY (r = - 0.471, p = <0.001). Concordance between Total Vit B12 and HCY (Kappa index = 0.51, p < 0.001); between holoTC and HCY (Kappa index = 0.52, p = <0.001) were statically significant but the latter had a better sensitivity and specificity. Also, statically significant association exists between Total Vitamin B12 and holoTC with HCY (p = <0.001). Therefore, it is ascertained that Active Vitamin B12 assay is a better test and can be considered as an early marker of vitamin B12 deficiency.

Fallacies of clinical studies on folic acid hazards in subjects with a low vitamin B12 status

A 2016 plea for revision of the 1 mg/day upper level of folic acid intake prompted us to comprehensively review the 1945-2017 literature on folic acid hazards in subjects with low cyanocobalamin. The concept of folic acid treatment 'masking' the anemia in undiagnosed cyanocobalamin deficiency, thereby delaying the diagnosis of neuropathy, does not account for the dissociation between the deficiency's hematologic and neurologic manifestations. Possible risks of this concept were addressed by 1963-1971 FDA rulings, classifying all folic acid preparations as prescription-only drugs, delivering ≤1 mg daily. The neuropathy in folic acid trials for 'pernicious anemia' is due to the singular use of folic acid-neuropathy improved or disappeared with replacement of folic acid by liver extract or cyanocobalamin. The hypothesis that cognitive impairment in 'subclinical' cyanocobalamin deficiency is folate-mediated is untenable. Of 6 papers specifically investigating this, none could prove that increased cognitive impairment was related to high folate intake. This review fully supports the safety of the 1 mg/day upper level for folic acid intake.

Deficiência de vitamina B12 e fatores associados em idosos institucionalizados

Resumo Objetivo Avaliar a frequência de deficiência de vitamina B12 e fatores associados em idosos institucionalizados. Método Analisamos 65 idosos, com idade média de 80±9 anos (61-113), de uma instituição geriátrica filantrópica de longa permanência. A dosagem sérica de vitamina B12 foi analisada e classificada em: normal (≥299 pg/mL), limítrofe (200-298 pg/mL) e deficiência (<200 pg/mL). Foi analisada a associação com tempo de permanência na instituição, declínio cognitivo e funcional, uso regular de biguanidas e inibidores de bomba de prótons, considerados fatores de risco para hipovitaminose B12, utilizando os testes de análise bivariada (paramétrica e não paramétrica) e regressão de Poisson. Resultados A deficiência de vitamina B12 estava presente em 21,5% e valores limítrofes em 32,3% da amostra. Dentre os idosos, 52,9% apresentavam demência de causas diversas, 49,2% hipertensão arterial, 29,2% com anemia (21,5% normocítica, 4,6% microcítica e 3,1% macrocítica), 18,5% diabéticos; 27,7% faziam uso de polifarmácia, com 12,3% em uso de metformina e 16,9% com inibidores de bomba de prótons. No modelo multivariado não houve associação entre a deficiência de vitamina B12 com as variáveis estudadas. Conclusão Observamos uma frequência importante de valores limítrofes e baixos de vitamina B12 nos pacientes dessa instuição geriátrica de cuidados permanentes, porém sem associação com os fatores de risco para sua deficiência estudado, o que torna importante a inclusão da dosagem sérica dessa vitamina na rotina de exames laboratoriais desse grupo.

Nutritional neuropathies

Neuropathies associated with nutritional deficiencies are routinely encountered by the practicing neurologist. Although these neuropathies assume different patterns, most are length-dependent, sensory axonopathies. Cobalamin deficiency neuropathy is the exception, often presenting with a non-length-dependent sensory neuropathy. Patients with cobalamin and copper deficiency neuropathy characteristically have concomitant myelopathy, whereas vitamin E deficiency is uniquely associated with a spinocerebellar syndrome. In contrast to those nutrients for which deficiencies produce neuropathies, pyridoxine toxicity results in a non-length-dependent sensory neuronopathy. Deficiencies occur in the context of malnutrition, malabsorption, increased nutrient loss (such as with dialysis), autoimmune conditions such as pernicious anemia, and with certain drugs that inhibit nutrient absorption. When promptly identified, therapeutic nutrient supplementation may result in stabilization or improvement of these neuropathies.

High frequency of anti-parietal cell antibody (APCA) and intrinsic factor blocking antibody (IFBA) in individuals with severe vitamin B12 deficiency – an observational study in primary care patients

Background

Vitamin B12 deficiency is common worldwide and is also linked to several diseases including autoimmune atrophic gastritis (AAG). The presence of anti-parietal cell antibodies (APCA) and/or intrinsic factor blocking antibodies (IFBA) is indicative of AAG that may develop into pernicious anemia. Both conditions are known to be associated with an increased risk of gastric carcinoma. The aim of this study was to estimate the frequency of individuals positive for APCA and IFBA antibodies in primary care patients with severe vitamin B12 deficiency.

Methods

An observational study was designed and 5468 consecutive patients from primary care with a request for vitamin B12 status were included and add-on testing for APCA and IFBA that were automatically registered if severe vitamin B12 deficiency was identified (<73.8 pmol/L). For patients included in the intervention, study demographic data, mean corpuscular volume (MCV) and hemoglobin values were collected.

Results

Seventy-seven patients with severe vitamin B12 deficiency were identified and out of these 44 (57%) presented with antibodies to APCA and 11 (14%) to IFBA, 25 (32.5%) had anemia, and 25 (32.5%) had macrocytosis. The majority of APCA and/or IFBA positive patients were found in the age group >70 years. Both anemia and macrocytosis were more common among APCA positive patients but the association was not statistically significant, neither was the correlation between IFBA status and anemia and/or macrocytosis. Among the patients with anemia, 10 (39%) had macrocytosis, although the rate of macrocytosis among patients with or without anemia did not differ significantly.

Conclusions

The automated analysis strategy of measuring antibodies to APCA and IFBA in patients with severe vitamin B12 deficiency, efficiently detected positivity in more than 60% the patients. The result point to the presence of a high rate of otherwise undetected AAG and the potential clinical utility of APCA and IFBA as markers in primary care.

Optogenetics sheds new light on tissue engineering and regenerative medicine

Optogenetics has demonstrated great potential in the fields of tissue engineering and regenerative medicine, from basic research to clinical applications. Spatiotemporal encoding during individual development has been widely identified and is considered a novel strategy for regeneration. A as a noninvasive method with high spatiotemporal resolution, optogenetics are suitable for this strategy. In this review, we discuss roles of dynamic signal coding in cell physiology and embryonic development. Several optogenetic systems are introduced as ideal optogenetic tools, and their features are compared. In addition, potential applications of optogenetics for tissue engineering are discussed, including light-controlled genetic engineering and regulation of signaling pathways. Furthermore, we present how emerging biomaterials and photoelectric technologies have greatly promoted the clinical application of optogenetics and inspired new concepts for optically controlled therapies. Our summation of currently available data conclusively demonstrates that optogenetic tools are a promising method for elucidating and simulating developmental processes, thus providing vast prospects for tissue engineering and regenerative medicine applications.

Methods to assess vitamin B12 bioavailability and technologies to enhance its absorption

Vitamin B12 (B-12) deficiency is still relatively common in low-, medium-, and high-income countries, mainly because of dietary inadequacy and, to a lesser extent, malabsorption. This narrative review is based on a systematic search of evidence on methods to assess B-12 bioavailability and technologies to enhance its absorption. A total of 2523 scientific articles identified in PubMed and 1572 patents identified in Orbit Intelligence were prescreened. Among the reviewed methods, Schilling's test and/or its food-based version (using cobalamin-labeled egg yolk) were used for decades but have been discontinued, largely because they required radioactive cobalt. The qualitative CobaSorb test, based on changes in circulating holo-transcobalamin before and after B-12 administration, and the 14C-labeled B-12 test for quantitative measurement of absorption of a low-dose radioactive tracer are currently the best available methods. Various forms of B-12 co-formulated with chemical enhancers (ie, salcaprozate sodium, 8-amino caprylate) or supplied via biotechnological methods (ie, microbiological techniques, plant cells expressing cobalamin binding proteins), encapsulation techniques (ie, emulsions, use of chitosan particles), and alternative routes of administration (ie, intranasal, transdermal administration) were identified as potential technologies to enhance B-12 absorption in humans. However, in most cases the evidence of absorption enhancement is limited.

Hypervitaminosis B12 - a new marker and predictor of prognostically unfavorable diseases

A high serum vitamin B12 level (hypercobalaminemia) is a underestimated anomaly. Clinically, it can be paradoxically accompanied by signs of deficiency, which are related to defects in tissue uptake of vitamin B12. The increase in the level of serum cobalamin occurs mainly in serious diseases that require early diagnosis: hemoblastosis, liver and kidney diseases, etc. This review presents data on the metabolism of vitamin B12 and the potential significance of increasing its level as a marker for the early diagnosis of these diseases.

[The investigation of the positive rate of intrinsic factor antibody and deficiency rate of vitamin B(12) in normal physical examination population]

Objective: To explore the positive rate of intrinsic factor antibody (IFAb) and level of vitamin B(12) (VitB(12)) in normal physical examination population and the possible relation between IFAb, VitB12 and sex, age, number of RBC, HGB and MCV. Methods: A total of 1 427 people who came to Peking Union Medical Colleague Hospital (PUMCH) for physical examination were enrolled. There were 758 males with average age of (52.5±14.5) years-old and 669 females with average age of (50.3±14.3) year-old. Beckman DxI800 automatic biochemical-immune analyzer and corollary reagents were used to analyze the level of serum IFAb and VitB(12). The results in different sex, age were documented and their correlation with the value of whole blood cell count was tested later on. Results: Among the 1 427 normal subjects, 66 (4.63%) were positive for IFAb. The positive rate for IFAb in the population≥40 years-old was higher than those<40 years-old (5.66% vs 1.48%, χ(2)=7.46, P=0.006). The deficiency rate of VitB(12) in the population<40 years-old, 40-59 years-old and ≥60 years-old was 2.22%, 2.51% and 5.50%, respectively (χ(2)=8.55, P=0.014). There were no difference between people with different sex in the positive rate of IFAb (5.15% for males and 4.04% for females, χ(2)=0.99, P=0.320) or in the deficiency rate of VitB(1)2 (3.83% for males and 2.69% for females, χ(2)=1.44, P=0.230). The results of multiple linear regression showed that HGB level of IFAb positive subjects was 3.05 g/L lower on average than those of IFAb negative, but IFAb had no effect on both RBC and MCV. There was no correlation between VitB(1)2 deficiency and HGB, RBC and MCV. Conclusion: The positive rate of IFAb and deficiency rate of VitB(1)2 increase as age increases. But the presence of VitB(12) deficiency is later than the positive findings of IFAb. IFAb showed some effects on the level of HGB, which may compensate the limitations of VitB(12) detection to some extent. It is necessary to check the IFAb and level of VitB(12) in people with middle or old ages.

Post renal transplant anemia: severity, causes and their association with graft and patient survival

Background

Post transplantation anemia (PTA) is common among kidney transplant patients. PTA is associated with increased graft loss and in most studies with increased mortality. However, the effect of the severity of anemia on this associations was not thoroughly evaluated.

Methods

Patients who underwent kidney transplantation in Rabin Medical Center (RMC) were included in the study. Data were collected during the years 2002–2016. Anemia was defined as hemoglobin (Hb) level less than 12 g/dL in women and less than 13 g/dL in men, in accordance with World Health Organization (WHO) criteria. Severe anemia was defined as hemoglobin lower than 11 g/dL. Primary outcome was a composite of patient and graft survival. We used univariate and multivariate models to evaluate association between severity and specific causes of anemia with the outcomes. As the risk associated with anemia changed over time we analyzed the risk separately for the early and the late period (before and after 1251 days).

Results

Our cohort included 1139 patients, 412 (36.2%) of which had PTA and 134 (11.7%) had severe anemia. On multivariable analysis, severe anemia was highly associated with the primary outcome at the early period (HR 6.26, 95% CI 3.74–10.5, p < 0.001). Anemia due to either AKI & acute rejection (11.9% of patients) or infection (16.7%), were associated with primary outcome at the early period (HR 9.32, 95% CI 5.3–26.41, p < 0.001 and HR 3.99, 95% CI 2.01–7.95, p < 0.001, respectively). There was non-significant trend for association between anemia due to Nutritional deficiencies (29.1%) and this outcome (HR 3.07, 95% CI 0.93–10.17, p = 0.067).

Conclusion

PTA is associated with graft loss and mortality especially during the first three years. Anemia severity affects this association. An anemia workup is recommended for PTA.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1244-y) contains supplementary material, which is available to authorized users.

Vitamin B12 Levels in Methamphetamine Addicts

Objective: It has been established that reduced vitamin B12 serum levels are associated with cognitive decline and mental illness. The chronic use of methamphetamine (MA), which is a highly addictive drug, can induce cognitive impairment and psychopathological symptoms. There are few studies addressing the association of MA with vitamin B12 serum levels. This study examined whether the serum levels of B12 are associated with MA addiction.

Methods: Serum vitamin B12, homocysteine (Hcy), glucose and triglyceride concentrations were measured in 123 MA addicts and 108 controls. In addition, data were collected on their age, marital status, level of education and Body Mass Index (BMI) for all participants. In the patient group, the data for each subject were collected using the Fagerstrom Test for Nicotine Dependence (FTND), the Alcohol Use Disorders Identification Test (AUDIT), and a drug use history, which included the age of onset, total duration of MA use, the number of relapses and addiction severity.

Results: Our results showed that MA addicts had lower vitamin B12 levels (p < 0.05) than those of healthy controls, but Hcy levels were not significantly different between the two groups (p > 0.05). Serum B12 levels were negatively correlated with the number of relapses in the MA group. Furthermore, binary logistics regression analysis indicated that the B12 was an influencing factor contributing to addiction severity.

Conclusion: The findings of this study suggest that some MA addicts might have vitamin B12 deficiency, and serum B12 levels may be involved in the prognosis of MA addiction.

Daily oral cyanocobalamin supplementation in Beagles with hereditary cobalamin malabsorption (Imerslund-Gräsbeck syndrome) maintains normal clinical and cellular cobalamin status

Background

Efficacy of PO cobalamin (Cbl) supplementation in dogs with hereditary Cbl malabsorption (Imerslund‐Gräsbeck syndrome, IGS) is unknown.

Objectives

To evaluate PO Cbl supplementation in Beagles with IGS previously treated parenterally. We hypothesized that 1 mg cyano‐Cbl daily PO would maintain clinical and metabolic remission.

Animals

Three client‐owned Beagles with IGS and 48 healthy control dogs.

Methods

Prospective study. Daily PO cyanocobalamin (cyano‐Cbl; 1 mg) supplementation was monitored for 13 (2 dogs) and 8 months (1 dog). Health status was assessed by owner observations. Methylmalonic acid (MMA)‐to‐creatinine concentrations were measured using an ultra‐performance liquid chromatography‐tandem mass spectrometry (UPLC‐TMS) method on urine samples collected monthly. Concurrent measurements of serum MMA concentration (n = 7; UPLC‐TMS) were available for 1 dog.

Results

All dogs remained in excellent health during PO supplementation. Urine MMA remained consistently low in 2 dogs (median, 2.5 mmol/mol creatinine; range, 1.2‐9; healthy dogs [n = 30], median, 2.9 mmol/mol creatinine; range, 1.3‐76.5). Urine MMA ranged from 38.9‐84.9 mmol/mol creatinine during the first 6 months in 1 dog already known to excrete comparable amounts when supplemented parenterally. Brief antibiotic treatment for an unrelated condition after 6 months resulted in low urine MMA (median, 2.8 mmol/mol creatinine; range, 1.9‐4.8) for the next 7 months. All concurrent serum MMA concentrations (median, 651 nmol/L; range, 399‐919) before and after month 6 were within the established reference interval (393‐1476 nmol/L; n = 48).

Conclusions and Clinical Importance

One milligram of cyano‐Cbl daily PO appears efficacious for maintaining normal clinical status and normal cellular markers of Cbl metabolism in Beagles with IGS.

Vitamin B12 deficiency and clinical laboratory: Lessons revisited and clarified in seven questions

The objective of this review article is to address the most frequently asked questions that pathologists and primary care physicians might face when dealing with a patient with suspicion of vitamin B12 deficiency. More specifically, the article mainly discusses the importance and prevalence of the deficit, how to recognize it, and the important role of a prompt diagnosis confirmation based on laboratory biomarkers for efficient replacement therapy.

Association of metformin use with vitamin B12 deficiency in the institutionalized elderly

Elderly people living in long term care institutions are particularly at risk of vitamin B₁₂ deficiency. The prevalence of vitamin B₁₂ deficiency was 34.9% among the 1996 institutionalized elderly residents in our previous study. The present retrospective study evaluated the association of metformin use with vitamin B₁₂ deficiency in the same group of patients. Of 1996 patients, 507 (25.4%) had diabetes, of which 188 received metformin treatment. The prevalence of vitamin B₁₂ deficiency in diabetic patients taking metformin was 53.2% compared with 31% (P < 0.001) of diabetic patients not taking metformin and 33.3% (P < 0.001) of those without diabetes. Among the vitamin B₁₂ deficient patients, diabetic patients taking metformin had lower serum vitamin B₁₂ concentration (97 pmol/L) than the diabetic patients not taking metformin (113 pmol/L, P < 0.001) and those without diabetes (111 pmol/L, P < 0.001). Subanalysis of 174 metformin users found that dose and duration of metformin use were significantly associated with vitamin B₁₂ deficiency. Adjusted odds ratio for those taking metformin ≥1500 mg /day was 2.72 (95% CI 1.11-6.7, P = 0.029) compared with those using metformin <1000mg/day. Adjusted odds ratio for those taking metformin>4 years was 3.00 (95% CI 1.35-6.68, P = 0.007) compared with those taking metformin <2 years. Prevalence of vitamin B₁₂ deficiency among those taking metformin ≥1500 mg/day for >2 years was 75.9% and was more than 2 times that of patients taking metformin <1500 mg/day for ≤2 years (35.3%). In conclusion, metformin use is associated with increased risk and severity of vitamin B₁₂ deficiency in the institutionalized elderly residents. Patients taking metformin ≥1500 mg/day for >2 years are particularly at risk. Testing for vitamin B₁₂ status before and regularly after the start of metformin may be considered.

Transcellular transport of cobalamin in aortic endothelial cells

Cobalamin [Cbl (or B₁₂)] deficiency causes megaloblastic anemia and a variety of neuropathies. However, homeostatic mechanisms of cyanocobalamin (CNCbl) and other Cbls by vascular endothelial cells are poorly understood. Herein, we describe our investigation into whether cultured bovine aortic endothelial cells (BAECs) perform transcytosis of B₁₂, namely, the complex formed between serum transcobalamin and B₁₂, designated as holo-transcobalamin (holo-TC). We show that cultured BAECs endocytose [⁵⁷Co]-CNCbl-TC (source material) via the CD320 receptor. The bound Cbl is transported across the cell both via exocytosis in its free form, [⁵⁷Co]-CNCbl, and via transcytosis as [⁵⁷Co]-CNCbl-TC. Transcellular mobilization of Cbl occurred in a bidirectional manner. A portion of the endocytosed [⁵⁷Co]-CNCbl was enzymatically processed by methylmalonic aciduria combined with homocystinuria type C (cblC) with subsequent formation of hydroxocobalamin, methylcobalamin, and adenosylcobalamin, which were also transported across the cell in a bidirectional manner. This demonstrates that transport mechanisms for Cbl in vascular endothelial cells do not discriminate between various β-axial ligands of the vitamin. Competition studies with apoprotein- and holo-TC and holo-intrinsic factor showed that only holo-TC was effective at inhibiting transcellular transport of Cbl. Incubation of BAECs with a blocking antibody against the extracellular domain of the CD320 receptor inhibited uptake and transcytosis by ∼40%. This study reveals that endothelial cells recycle uncommitted intracellular Cbl for downstream usage by other cell types and suggests that the endothelium is self-sufficient for the specific acquisition and subsequent distribution of circulating B₁₂ via the CD320 receptor. We posit that the endothelial lining of the vasculature is an essential component for the maintenance of serum-tissue homeostasis of B₁₂.-Hannibal, L., Bolisetty, K., Axhemi, A., DiBello, P. M., Quadros, E. V., Fedosov, S., Jacobsen, D. W. Transcellular transport of cobalamin in aortic endothelial cells.

A Tale of Treatable Infantile Neuroregression and Diagnostic Dilemma with Glutaric Aciduria Type I

Nutritional deficiencies related neurological manifestations are not uncommon in infants and children. Here, we describe an infant with Vitamin B12 deficiency due to depleted maternal Vitamin B12 status presenting with progressive encephalopathy and extrapyramidal signs. Diagnosis of infantile tremor syndrome was established in our patient based on the clinical and biochemical parameters. Magnetic resonance imaging had shown frontotemporal atrophy with widened Sylvian fissures and prominent cerebrospinal fluid spaces. Clinical and imaging findings might create a diagnostic dilemma with glutaric aciduria type I. Knowledge and identification of infantile tremor syndrome are essential, as it is a potentially treatable disorder. Our patient had significant developmental gains with Vitamin B12 treatment and infant stimulation program. Vitamin B12 deficiency must be looked for as a cause of neuroregression in children hailing from low socioeconomic status, infants of vegetarian mother, and infants with delayed or improper weaning. Screening for Vitamin B12 deficiency is essential in all infants and children with unexplained neuroregression, as this disorder is potentially treatable. More population-based studies in India are needed to explore the prevalence of Vitamin B12 deficiency in pregnant and lactating women and also to assess the need for Vitamin B12 supplementation during pregnancy and lactation.

Vitamin B12 Deficiency and the Role of Gender: A Cross-Sectional Study of a Large Cohort

Background: Vitamin B12 deficiency is associated with hematological, neurological, and cardiovascular consequences. Epidemiologic data on these related illnesses indicate gender differences. Methods: A cross-sectional study was designed to examine gender differences in vitamin B12 deficiency among a healthy population. Data from healthy individuals aged 18–65, who were provided with a routine medical evaluation during 2000–2014, were retrieved from the medical charts. Individuals with background illnesses and those who had used medications or nutritional supplements were excluded. Vitamin B12 deficiency was defined by 2 cutoff values (206 and 140 pmol/L). The multivariate analysis was adjusted for age, body mass index, estimated glomerular filtration rate, hyperhomocysteinemia, folate deficiency, albumin, and transferrin saturation. Sensitivity analyses were implemented by excluding individuals with anemia, hyperhomocysteinemia, or folate deficiency and by age stratification. Results: In all, 7,963 individuals met the inclusion criteria. Serum vitamin B12 mean levels were 312.36 and 284.31 pmol/L for women and men respectively (p < 0.001). Deficiency prevalence was greater for men (25.5%) in comparison with women (18.9%; p < 0.001). Men were strongly associated with severe deficiency (adjusted OR 2.26; 95% CI 1.43–3.56). Conclusions: Among the healthy population, men are susceptible to vitamin B12 deficiency. This can be explained by neither diet habits nor estrogen effects. Genetic variations are therefore hypothesized to play a role.

Prospective long-term evaluation of parenteral hydroxocobalamin supplementation in juvenile beagles with selective intestinal cobalamin malabsorption (Imerslund-Gräsbeck syndrome)

BACKGROUND

Prospective studies on maintenance treatment for Beagles with hereditary selective cobalamin (Cbl) malabsorption (Imerslund-Gräsbeck syndrome, IGS) are lacking. In our experience, measurement of methylmalonic acid (MMA), a Cbl-dependent metabolite, seems more helpful to monitor Cbl status as compared with serum Cbl concentrations.

OBJECTIVES

To evaluate a standardized Cbl supplementation scheme in Beagles with IGS. We hypothesized that a single parenteral dose of 1 mg hydroxocobalamin (OH-Cbl) would maintain clinical and metabolic remission for up to 2 months.

ANIMALS

Six client-owned juvenile Beagles with genetically confirmed IGS and 28 healthy control dogs.

METHODS

Prospective study. Monthly IM OH-Cbl (1 mg) supplementation was done over a median of 9 months (range, 6-13) in 6 dogs, followed by bimonthly (every 2 months) injections in 5 dogs over a median of 6 months (range, 3-10). Health status was assessed by routine clinical examinations at injection time points and owner observations. Voided urine samples were collected immediately before OH-Cbl injections for measurement of MMA-to-creatinine concentrations using a gas-liquid chromatography-tandem mass spectrometry (GC-MS) method.

RESULTS

All dogs were clinically healthy while receiving monthly and bimonthly OH-Cbl supplementation. Urinary MMA results in healthy dogs ranged from 1.3 to 76.5 mmol/mol creatinine (median, 2.9). Median urinary MMA concentrations did not differ between dogs with IGS receiving monthly (n = 49; 5.3 mmol/mol creatinine; range, 2.3-50.4) and bimonthly (n = 31; 5.3 mmol/mol creatinine; range, 1.6-50) injections.

CONCLUSIONS AND CLINICAL IMPORTANCE

A maintenance parenteral dose of 1 mg OH-Cbl monthly or bimonthly appears adequate in Beagles with IGS monitored by metabolic testing.

Vitamin B12

The biosynthesis of B₁₂, involving up to 30 different enzyme-mediated steps, only occurs in bacteria. Thus, most eukaryotes require an external source of B₁₂, and yet the vitamin appears to have only two functions in eukaryotes: as a cofactor for the enzymes methionine synthase and methylmalonylCoA mutase. These two functions are crucial for normal health in humans, and in particular, the formation of methionine is essential for providing methyl groups for over 100 methylation processes. Interference with the methionine synthase reaction not only depletes the body of methyl groups but also leads to the accumulation of homocysteine, a risk factor for many diseases. The syndrome pernicious anemia, characterized by lack of intrinsic factor, leads to a severe, sometimes fatal form of B₁₂ deficiency. However, there is no sharp cutoff for B₁₂ deficiency; rather, there is a continuous inverse relationship between serum B₁₂ and a variety of undesirable outcomes, including neural tube defects, stroke, and dementia. The brain is particularly vulnerable; in children, inadequate B₁₂ stunts brain and intellectual development. Suboptimal B₁₂ status (serum B₁₂<300pmol/L) is very common, occurring in 30%-60% of the population, in particular in pregnant women and in less-developed countries. Thus, many tens of millions of people in the world may suffer harm from having a poor B₁₂ status. Public health steps are urgently needed to correct this inadequacy.

Vitamin B12 deficiency after esophagectomy with gastric tube reconstruction for esophageal cancer

The aim of this study is to determine the prevalence and incidence of vitamin B12 deficiency after esophagectomy for cancer. It is unknown if patients after esophagectomy with gastric tube reconstruction are at an increased risk for vitamin B12 deficiency. A cross-sectional cohort (group A) and a prospective cohort (group B) of patients who underwent esophagectomy for cancer in two tertiary referral centers in the Netherlands were included. Serum levels of holo-transcobalamin (Holo-TC) and methyl malonic acid (MMA) were determined. Vitamin B12 deficiency was defined as Holo-TC < 21 pmol/L and/or MMA > 0.45 μmol/L. Vitamin B12 status was assessed in group A at a single time point between one and three years postoperatively and before and every three months after resection in group B. Ninety-nine patients were analyzed in group A. The median time between surgery and analysis of vitamin B12 deficiency was 19.3 months. In 11 of 99 (11%) patients, vitamin B12 deficiency was detected. In group B, 5 of 88 (5.6%) patients had vitamin B12 deficiency preoperatively, and another 9 (10.2%) patients developed vitamin B12 deficiency after the operation at a median time of 6 months postoperatively. The estimated one-year incidence of vitamin B12 deficiency was 18.2%. None of the patients with vitamin B12 deficiency had a megaloblastic anemia. Vitamin B12 deficiency can be anticipated in 18% of patients after esophagectomy with gastric tube reconstruction for cancer. During follow-up, Holo-TC and MMA levels should be measured to detect vitamin B12 deficiency and commence treatment timely.

Green-Light-Induced Inactivation of Receptor Signaling Using Cobalamin-Binding Domains

Optogenetics and photopharmacology provide spatiotemporally precise control over protein interactions and protein function in cells and animals. Optogenetic methods that are sensitive to green light and can be used to break protein complexes are not broadly available but would enable multichromatic experiments with previously inaccessible biological targets. Herein, we repurposed cobalamin (vitamin B12) binding domains of bacterial CarH transcription factors for green-light-induced receptor dissociation. In cultured cells, we observed oligomerization-induced cell signaling for the fibroblast growth factor receptor 1 fused to cobalamin-binding domains in the dark that was rapidly eliminated upon illumination. In zebrafish embryos expressing fusion receptors, green light endowed control over aberrant fibroblast growth factor signaling during development. Green-light-induced domain dissociation and light-inactivated receptors will critically expand the optogenetic toolbox for control of biological processes.

Impact of baseline vitamin B12 status on the effect of vitamin B12 supplementation on neurologic function in older people: secondary analysis of data from the OPEN randomised controlled trial

BACKGROUND/OBJECTIVES

The available evidence from randomised controlled trials suggests that vitamin B12 supplementation does not improve neurologic function in older people with marginal but not deficient Vitamin B12 status. This secondary analysis used data from the Older People and Enhanced Neurological function (OPEN) randomised controlled trial to assess whether baseline vitamin B12 status or change in vitamin B12 status over 12 months altered the effectiveness of dietary vitamin B12 supplementation on neurologic function in asymptomatic older people with depleted vitamin B12 status at study entry.

SUBJECTS/METHODS

Vitamin B12 status was measured as serum concentrations of vitamin B12, holotranscobalamin, homocysteine and via a composite indicator (cB12). Neurological function outcomes included eleven electrophysiological measures of sensory and motor components of peripheral and central nerve function. Linear regression analyses were restricted to participants randomised into the intervention arm of the OPEN trial (n=91).

RESULTS

Analyses revealed an inconsistent pattern of moderate associations between some measures of baseline vitamin B12 status and some neurological responses to supplementation. The directions of effect varied and heterogeneity in effect across outcomes could not be explained according to type of neurological outcome. There was no evidence of differences in the neurological response to vitamin B12 supplementation according to change from baseline over 12 months in any indicator of B12 status.

CONCLUSIONS

This secondary analysis of high-quality data from the OPEN trial provides no evidence that baseline (or change from baseline) vitamin B12 status modifies the effect of vitamin B12 supplementation on peripheral or central nerve conduction among older people with marginal vitamin B12 status. There is currently insufficient evidence of efficacy for neurological function to support population-wide recommendations for vitamin B12 supplementation in healthy asymptomatic older people with marginal vitamin B12 status.

A double-blind, randomized, comparative study of the use of a combination of uridine triphosphate trisodium, cytidine monophosphate disodium, and hydroxocobalamin, versus isolated treatment with hydroxocobalamin, in patients presenting with compressive neuralgias

CONTEXT

This paper reports on the results of treatment of compressive neuralgia using a combination of nucleotides (uridine triphosphate trisodium [UTP] and cytidine monophosphate disodium [CMP]) and vitamin B12.

OBJECTIVES

To assess the safety and efficacy of the combination of nucleotides (UTP and CMP) and vitamin B12 in patients presenting with neuralgia arising from neural compression associated with degenerative orthopedic alterations and trauma, and to compare these effects with isolated administration of vitamin B12.

METHODS

A randomized, double-blind, controlled trial, consisting of a 30-day oral treatment period: Group A (n=200) receiving nucleotides + vitamin B12, and Group B (n=200) receiving vitamin B12 alone. The primary study endpoint was the percentage of subjects presenting pain visual analog scale (VAS) scores ≤20 at end of study treatment period. Secondary study endpoints included the percentage of subjects presenting improvement ≥5 points on the patient functionality questionnaire (PFQ); percentage of subjects presenting pain reduction (reduction in VAS scores at study end in relation to pretreatment); and number of subjects presenting adverse events.

RESULTS

The results of this study showed a more expressive improvement in efficacy evaluations among subjects treated with the combination of nucleotides + vitamin B12, with a statistically significant superiority of the combination in pain reduction (evidenced by VAS scores). There were adverse events in both treatment groups, but these were transitory and no severe adverse event was recorded during the study period. Safety parameters were maintained throughout the study in both treatment groups.

CONCLUSION

The combination of uridine, cytidine, and vitamin B12 was safe and effective in the treatment of neuralgias arising from neural compression associated with degenerative orthopedic alterations and trauma.

Pernicious Anemia Associated Cobalamin Deficiency and Thrombotic Microangiopathy: Case Report and Review of the Literature

A 43-year-old Hispanic male without significant previous medical history was brought to emergency department for syncope following a blood draw to investigate a 40 lbs weight loss during the past 6 months associated with decreased appetite and progressive fatigue. The patient also reported a 1-month history of jaundice. On examination, he was hemodynamically stable and afebrile with pallor and diffuse jaundice but without skin rash or palpable purpura. Normal sensations and power in all extremities were evident on neurological exam. Presence of hemolytic anemia, schistocytosis, thrombocytopenia, and elevated lactate dehydrogenase (LDH) was suggestive of thrombotic thrombocytopenic purpura (TTP). However, presence of leukopenia, macrocytes, and an inadequate reticulocyte response to the degree of anemia served as initial clues to an alternative diagnosis. Two and one units of packed red blood cells were transfused on day 1 and day 3, respectively. In addition, one unit of platelets was transfused on day 2. Daily therapeutic plasma exchange (TPE) was initiated and continued until ADAMTS-13 result ruled out TTP. A low cobalamin (vitamin B12) level was evident at initial laboratory work-up and subsequent testing revealed positive intrinsic factor-blocking antibodies supporting a diagnosis of pernicious anemia with severe cobalamin deficiency. Hematological improvement was observed following vitamin B12 supplementation. The patient was discharged and markedly improved on day 9 with outpatient follow-up for cobalamin supplementation.

Potential Links between Impaired One-Carbon Metabolism Due to Polymorphisms, Inadequate B-Vitamin Status, and the Development of Alzheimer's Disease

Alzheimer's disease (AD) is the major cause of dementia and no preventive or effective treatment has been established to date. The etiology of AD is poorly understood, but genetic and environmental factors seem to play a role in its onset and progression. In particular, factors affecting the one-carbon metabolism (OCM) are thought to be important and elevated homocysteine (Hcy) levels, indicating impaired OCM, have been associated with AD. We aimed at evaluating the role of polymorphisms of key OCM enzymes in the etiology of AD, particularly when intakes of relevant B-vitamins are inadequate. Our review indicates that a range of compensatory mechanisms exist to maintain a metabolic balance. However, these become overwhelmed if the activity of more than one enzyme is reduced due to genetic factors or insufficient folate, riboflavin, vitamin B6 and/or vitamin B12 levels. Consequences include increased Hcy levels and reduced capacity to synthetize, methylate and repair DNA, and/or modulated neurotransmission. This seems to favor the development of hallmarks of AD particularly when combined with increased oxidative stress e.g., in apolipoprotein E (ApoE) ε4 carriers. However, as these effects can be compensated at least partially by adequate intakes of B-vitamins, achieving optimal B-vitamin status for the general population should be a public health priority.