Disorders of cobalamin (Vitamin B12) metabolism: Emerging concepts in pathophysiology, diagnosis and treatment

Salvage pathway of vitamin B12 absorption in chickens with mutant tumor virus a receptor

The tumor virus A receptor (TVA), a member of the low-density lipoprotein receptor (LDLR) family, serves as an entry receptor for Avian Leukosis Virus (ALV) subgroups A and K, as well as a receptor for vitamin B12 bound to transcobalamin. Naturally occurring genetic variants in the TVA gene determine susceptibility or resistance to ALV-A and -K, but the effects of these mutated TVA on vitamin B12 uptake have not been investigated systemically. We found four TVA variants comprising the wild type (TVAWT), a single nucleotide polymorphism variant (TVASNP), and two partial deletions in the splicing branch point region (TVAR). This study investigates the relationship between the various genotypes of TVA alleles and uptake of vitamin B12 in chickens. A protein interaction model suggested that mutant TVAs (i.e., TVASNP, TVAR) may have reduced ability to take up vitamin B12 due to a disrupted LDL-A domain, a pivotal region involved in vitamin B12 uptake; however, we found no significant difference in absorption of vitamin B12 in TVAWT and TVASNP chickens, or levels of its metabolite in serum. Notably, TVAR chickens had significantly higher levels of vitamin B12 than TVAWT chickens, a finding contrary to the predicted lower uptake. Expression of vitamin B12 carrier related genes (i.e., AMN, GIF, and TCN2) in chickens showed a stepwise increase: TVAWT > TVASNP > TVAR. These results suggest a mechanism by which mutant TVA chickens with a disrupted TVA protein acquire natural resistance to ALV-A -K, with no impairment of vitamin B12 metabolism.

Serum Transcobalamin Concentration in Cats-Method Validation and Evaluation in Chronic Enteropathies and Other Conditions

Hypocobalaminemia is common in cats with chronic enteropathy (FCE). However, the disruptions in cobalamin metabolism are not fully understood and may vary across species. Cobalamin is distributed to target tissues via binding to transcobalamin (TC) in blood, which has not been evaluated in cats. Thus, an in-house sandwich-ELISA was established to evaluate serum total TC concentrations in cats with FCE. Surplus sera served to analytically validate the assay, and serum TC concentrations were compared among cats with FCE and other diseases (gastrointestinal neoplasia, cholangiohepatopathy, and other neoplastic or non-neoplastic conditions) and healthy controls. Observed-to-expected ratios for serial dilutions ranged from 72.4 to 145.6% and were 75.1-126.7% for spiking-and-recovery. Intra- and inter-assay variability was <17.7% and <17.2% and the preliminary reference interval for feline serum TC was <160-2795 aU/L (lower detection limit: 160 aU/L). Serum TC levels were significantly decreased (p = 0.0067) but not correlated with paired cobalamin concentrations in FCE. Hypertranscobalaminemia predominated with hypercobalaminemia, reaching the highest levels in advanced-stage chronic kidney disease (CKD) cases. TC variations in cobalamin deficiency states with FCE may be linked to inflammation or autoantibodies. This and possible links between serum TC variation in FCE, intracellular cobalamin availability, response to supplementation, and concurrent CKD require further exploration.

Decreased cobalamin sensitivity and biological aging acceleration in the general population

BACKGROUND

The evidence on the association between cobalamin (Cbl) and aging or relevant outcomes is limited and controversial. We aimed to investigate the relationships between cobalamin intake- and function-related biomarkers and biological aging.

METHODS

The study encompassed 22,812 participants aged 20 years and older from the National Health and Nutrition Examination Survey. A panel of biomarkers or algorithms was used to assess biological aging, including Klemera-Doubal Age Acceleration (KDMAccel), Phenotypic age acceleration (PhenoAgeAccel), telomere length, α-Klotho, and PhenoAge advancement. Weighted generalized linear regression analysis was used to assess the associations between cobalamin-intake biomarkers (serum cobalamin, cobalamin intake from food, cobalamin supplement use, serum methylmalonic acid [MMA], and homocysteine [Hcy]) and function-related biomarkers (functional cobalamin deficiency and cobalamin insensitivity index).

RESULTS

Among the 22,812 individuals, the weighted mean (SE) age was 48.3 (0.2) years and 48.0% were males. Unexpectedly, serum and dietary cobalamin as well as serum MMA and Hcy levels were positively associated with most indicators of biological aging. Cobalamin sensitivity was assessed by the combination of binary Cbllow/high and MMAlow/high or Hcylow/high (cutoff values: 400 pg/mL for cobalamin, 250 nmol/L for MMA, and 12.1 μmol/l for Hcy) and a newly constructed cobalamin insensitivity index (based on the multiplicative term of serum cobalamin and serum MMA or Hcy). The multivariable-adjusted β (95%CIs) of KDMAccel in the MMAlowCbllow, MMAlowCblhigh, MMAhighCbllow, and MMAhighCblhigh groups were reference, 0.27 (0.03 to 0.51), 0.85 (0.41 to 1.29), and 7.97 years (5.77 to 10.17) respectively, which were consistent for the combination of serum Hcy and cobalamin. Both cobalamin insensitivity indices were robustly associated with biological aging acceleration in a dose-response pattern (each p < 0.001).

CONCLUSIONS

Decreased cobalamin sensitivity but not cobalamin insufficiency might be associated with biological aging acceleration. Further studies would improve understanding of the underlying mechanisms between decreased cobalamin sensitivity and biological aging acceleration.

Just a vitamin? Should cobalamin (Vitamin B12) levels be checked in children with neurological disadvantages?

OBJECTIVE

The assay of serum cobalamin (Cbl) level is commonly used to diagnose Cbl deficiency. Unexpectedly, the elevated Cbl levels may be determined in some of the patients and its interpretation is difficult. We investigated the association between elevated Cbl levels and a variety of clinical entities in patients presenting with various neurological symptoms.

METHODS

The data were obtained from the patients' electronic medical records in a tertiary hospital affiliated with a university. The pediatric patients with serum Cbl levels above 1000 pg/mL were included in the study. The patients with serum Cbl levels below 900 pg/mL and above 200 pg/mL constituted the control group.

RESULTS

The mean Cbl level of the patients with neurological problems was 1424.2±354.2 pg/mL, whereas the average Cbl level of neurologically healthy was 1316±317.8 pg/mL, and the difference was statistically significant. While the rate of having neurological deficits or symptoms in the study group was found to be 24%, this rate was only 18% in the control group. Unexpectedly, despite elevated Cbl level, the high mean corpuscular volume rate was higher in the study group compared to the control group.

CONCLUSION

This study highlights the importance of the disorders of Cbl metabolism in patients presenting with various neurological symptoms. In children with neurological deficits, serum Cbl levels should be checked. In case of high Cbl level is determined, patients should be followed up closely, and further investigations should be performed in terms of Cbl metabolism disorders.

An Adenosylcobalamin Specific Whole-Cell Biosensor

Vitamin B12 (cobalamin) is essential for human health and its deficiency results in anemia and neurological damage. Vitamin B12 exists in different forms with various bioactivity but most sensors are unable to discriminate between them. Here, a whole-cell agglutination assay that is specific for adenosylcobalamin (AboB12), which is one of two bioactive forms, is reported. This biosensor consists of Escherichia coli that express the AdoB12 specific binding domain of CarH at their surface. In the presence of AdoB12, CarH forms tetramers, which leads to specific bacterial cell-cell adhesions and agglutination. These CarH tetramers disassemble upon green light illumination such that reversion of the bacterial aggregation can serve as internal quality control. The agglutination assay has a detection limit of 500 nм AdoB12, works in protein-poor biofluids such as urine, and has high specificity to AdoB12 over other forms of vitamin B12 as also demonstrated with commercially available supplements. This work is a proof of concept for a cheap and easy-to-readout AdoB12 sensor that can be implemented at the point-of-care to monitor high-dose vitamin B12 supplementation.

Vitamin B12 in Cats: Nutrition, Metabolism, and Disease

Cobalamin is a water-soluble molecule that has an important role in cellular metabolism, especially in DNA synthesis, methylation, and mitochondrial metabolism. Cobalamin is bound by intrinsic factor (IF) and absorbed in the ileal tract. The IF in cats is synthesized exclusively by pancreatic tissue. About 75% of the total plasma cobalamin in cats is associated with transcobalamin II, while in this species, transcobalamin I is not present. In cats, the half-life of cobalamin is 11-14 days. Diagnostic biomarkers for B12 status in cats include decreased levels of circulating total cobalamin and increased levels of methylmalonic acid. The reference interval for serum cobalamin concentrations in cats is 290-1500 ng/L, and for the serum methylmalonic acid concentration, it is 139-897 nmol/L. Therapy for hypocobalaminemia mainly depends on the underlying disease. In some cases, subcutaneous or intramuscular injection of 250 μg/cat is empirically administered. In recent years, it has been demonstrated that oral cobalamin supplementation can also be used successfully in dogs and cats as a less invasive alternative to parental administration. This review describes the current knowledge regarding B12 requirements and highlights improvements in diagnostic methods as well as the role of hypocobalaminemia in its associated diseases.

A Comprehensive Study: Traditional and Cutting-Edge Analytical Techniques for the Biomarker Based Detection of the Micronutrients & POC Sensing Directions for Next-Generation Diagnostic

Micronutrient deficiency is wide spread and highly affects morbidity, mortality, and well-being of human beings. Micronutrient deficiency gradually manifests into diseases, which effects pathophysiology directly or indirectly. There is an imprecision in the diagnosis of micronutrient deficiency because of two causes; the selection of the standard biomarker and the diagnostic technique used. In appropriate diagnosis could increase the severity of the disorder. Instead of a single a combination of biomarkers can give more stringent results for micronutrient testing. Several traditional analytical techniques are used for diagnosis but HPLC, ELISA & LCMS/MS are most sensitive and reliable methods used by CLSIA-certified labs. However, these techniques require well-equipped, centralized laboratory facilities. The diagnostic era moves toward the Point of Care Testing (POCT), a boon in emerging diagnostics, breaking all paradigms of traditional analytical techniques. POCT led us toward the development of biosensors, which encompasses many techniques like paper-based sensors, microfluidic chip, wearable devices, and smartphone-assisted diagnostics, which become more popular diagnostic tools. This outlook summarizes the micronutrients like vitamins A, B5, B6, B7, B9, B12 C, D, and E and Minerals like iron, calcium, zinc, magnesium, and sodium; along with its biomarkers, analytical techniques, and point of care innovation in micronutrients.

Data-driven clustering approach to identify novel phenotypes using multiple biomarkers in acute ischaemic stroke: A retrospective, multicentre cohort study

BACKGROUND

Acute ischaemic stroke (AIS) is a highly heterogeneous disorder and warrants further investigation to stratify patients with different outcomes and treatment responses. Using a large-scale stroke registry cohort, we applied data-driven approach to identify novel phenotypes based on multiple biomarkers.

METHODS

In a nationwide, prospective, 201-hospital registry study taking place in China between August 01, 2015 and March 31, 2018, the patients with AIS who were over 18 years of age and admitted to the hospital within 7 days from symptom onset were included. 92 biomarkers were included in the analysis. In the derivation cohort (n=9539), an unsupervised Gaussian mixture model was applied to categorize patients into distinct phenotypes. A classifier was developed using the most important biomarkers and was applied to categorize patients into their corresponding phenotypes in an validation cohort (n=2496). The differences in biological features, clinical outcomes, and treatment response were compared across the phenotypes.

FINDINGS

We identified four phenotypes with distinct characteristics in 9288 patients with non-cardioembolic ischaemic stroke. Phenotype 1 was associated with abnormal glucose and lipid metabolism. Phenotype 2 was characterized by inflammation and abnormal renal function. Phenotype 3 had the least laboratory abnormalities and small infarct lesions. Phenotype 4 was characterized by disturbance in homocysteine metabolism. Findings were replicated in the validation cohort. In comparison with phenotype 3, the risk of stroke recurrence (adjusted hazard ratio [aHR] 2.02, 95% confidence intervals [CI] 1.04-3.94), and mortality (aHR 18.14, 95%CI 6.62-49.71) at 3-month post-stroke were highest in phenotype 2, followed by phenotype 4 and phenotype 1, after adjustment for age, gender, smoking, drinking, history of stroke, hypertension, diabetes mellitus, dyslipidemia, and coronary heart disease. The Monte Carlo simulation showed that the patients with phenotype 2 could benefit from high-intensity statin therapy.

INTERPRETATION

A data-driven approach could aid in the identification of patients at a higher risk of adverse clinical outcomes following non-cardioembolic ischaemic stroke. These phenotypes, based on different pathophysiology, can suggest individualized treatment plans.

FUNDING

Beijing Natural Science Foundation (grant number Z200016), Beijing Municipal Committee of Science and Technology (grant number Z201100005620010), National Natural Science Foundation of China (grant number 82101360, 92046016, 82171270), Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (grant number 2019-I2M-5-029).

Effects of maternal folate and vitamin B12 on gestational diabetes mellitus: a dose-response meta-analysis of observational studies

To comprehensively estimate the association of gestational diabetes mellitus (GDM) risk with maternal red blood cell (RBC) folate, plasma/serum folate, dose and duration of folic acid supplement (FAS) intake and vitamin B12 separately. PubMed, Web of science, CNKI, and Wanfang Databases were searched through March 26, 2021. We synthesized data using random-effects model meta-analysis in Stata 12.0. Sensitivity, subgroup and dose-response analyses were also performed. The certainty of evidence was evaluated using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE). Twenty six datasets from thirteen eligible observational studies were included in the study. We found a significant increase of GDM risk with the highest versus lowest category of RBC folate (OR = 1.96, 95% CI: 1.48-2.61, I2 = 0.0%, moderate-certainty evidence) and plasma/serum folate (OR = 1.23, 1.02-1.48, I2 = 57.8%, low-certainty evidence). The dose-response analysis revealed that each 200 ng/ml increase in RBC folate was significantly associated with 8% higher GDM risk. No significant association between dose of FAS intake and GDM risk was found with very low cetainty. Meanwhile, longer duration (≥3 months) of FAS conferred 56% significant higher GDM risk (OR = 1.56, 1.02-2.39, very low certainty evidence). No significant association of GDM risk with highest plasma/serum B12 was observed compared to lowest B12 (OR = 0.77, 0.58-1.02, very low-certainty evidence). Moderate-certainty evidence suggests that higher RBC folate appears to significantly increase GDM risk. Higher plasma/serum folate may increase GDM risk but with low certainty. Further well-designed trials or prospective studies are needed.

Trends in Vitamin B12 Supply and Prevalence of Inadequate Intake in Africa: Regional and Country-Specific Estimates

BACKGROUND

In Africa, little is known about the epidemiological significance of vitamin B12 deficiency.

OBJECTIVE

To analyze regional and country-specific trends (1990-2017) in vitamin B12 supply in Africa and estimate the prevalence of inadequate intake.

METHODS

National food balance data compiled by Food and Agriculture Organization for 45 African countries were used. Per capita food supplies for 95 commodities were transformed into B12 contents (µg/capita/day) assuming no fortification and B12 density was determined per 1000 kcal. Estimated Average Requirement cut point method was used for estimating the prevalence of inadequate intake.

RESULTS

Over the period, the mean per capita B12 supply in Africa significantly increased by 12.7% from 2.02 to 2.27 µg/capita/day (z = 5.27, P < .001). However, the B12 density remained below the reference goal of 0.8 µg/1000 kcal. In 2017, the B12 supplies (µg/capita/day) in Northern (3.52), Central (3.15), and Southern Africa (2.99) were considerably higher than Western (2.10) and Eastern Africa (1.36) regions. The supply in upper-middle- or high-income countries (3.21) was also substantially higher than low- (1.58) and low-middle-income (2.58) countries. In 2017, the B12 supplies ranged from 5.95 in Mauritius to 0.66 in Ethiopia. Similarly, the nutrient density extended from 1.88 in Gambia to 0.28 in Ethiopia. In Africa, the estimated prevalence of inadequate intake declined from 48.1% in 1990 to 29.9% in 2007 and resurged to 40.6% in 2017. In 2017, the prevalence of inadequate intake was nearly universal (> 90%) in 4 countries and exceeded 50% in 8 more countries.

CONCLUSION

Many African countries have major deficits in vitamin B12 supply.

Elevated holo-transcobalamin in Gaucher disease type II: A case report

Gaucher disease (GD), one of the most common lysosomal disorders, is caused by deficiency of β-glucocerebrosidase. Based on the presence and severity of neurological complications, GD is classified into types I, II (the most severe form), and III. Abnormalities in systemic markers of vitamin B₁₂ (B₁₂ ) metabolism have been reported in GD type I patients, suggesting a higher prevalence of B₁₂ deficiency in these patients. A 2-month-old male with GD type II was admitted to the hospital presenting jaundice, hepatosplenomegaly, and ichthyosis. At admission, cholestasis and ascites, abnormal liver function enzymes, prolonged prothrombin time, and high levels of B₁₂ were confirmed. Analysis of biomarkers of B₁₂ status revealed elevated B₁₂ and holo-transcobalamin (holo-TC) levels. The B₁₂ profile found in our patient is the opposite to what is described for GD type I patients. Holo-TC may increase in inflammatory states or due to liver diseases. In GD, the accumulation of glucocerebroside may be a trigger that initiates a systemic inflammatory reaction, characterized by macrophage activation. We suggest higher levels of holo-TC could be associated with a more severe (neuronopathic) GD, and be a biomarker of GD type II.

Association of Maternal Folate and Vitamin B12 in Early Pregnancy With Gestational Diabetes Mellitus: A Prospective Cohort Study

OBJECTIVE

To investigate the association of folate and vitamin B₁₂ in early pregnancy with gestational diabetes mellitus (GDM) risk.

RESEARCH DESIGN AND METHODS

The data of this study were from a subcohort within the Shanghai Preconception Cohort Study. We included pregnancies with red blood cell (RBC) folate and vitamin B₁₂ measurements at recruitment (between 9 and 13 gestational weeks) and those with three samples available for glucose measurements under an oral glucose tolerance test. GDM was diagnosed between 24 and 28 weeks' gestation. Odds ratio (OR) and 95% CI of having GDM was used to quantify the association.

RESULTS

A total of 1,058 pregnant women were included, and GDM occurred in 180 (17.01%). RBC folate and vitamin B₁₂ were significantly higher in pregnancies with GDM than those without GDM (P values were 0.045 and 0.002, respectively) and positively correlated with 1-h and 2-h serum glucose. Daily folic acid supplementation in early pregnancy increases the risk of GDM; OR (95% CI) was 1.73 (1.19-2.53) (P = 0.004). Compared with RBC folate <400 ng/mL, pregnancies with RBC folate ≥600 ng/mL were associated with ∼1.60-fold higher odds of GDM; the adjusted OR (95% CI) was 1.58 (1.03-2.41) (P = 0.033). A significant trend of risk effect on GDM risk across categories of RBC folate was observed (P _trend = 0.021). Vitamin B₁₂ was significantly associated with GDM risk (OR 1.14 per 100 pg/mL; P = 0.002). No significant association of serum folate and percentile ratio of RBC folate/vitamin B₁₂ with GDM was observed.

CONCLUSIONS

Higher maternal RBC folate and vitamin B₁₂ levels in early pregnancy are significantly associated with GDM risk, while the balance of folate/vitamin B₁₂ is not significantly associated with GDM.

Review of cobalamin status and disorders of cobalamin metabolism in dogs

Disorders of cobalamin (vitamin B₁₂) metabolism are increasingly recognized in small animal medicine and have a variety of causes ranging from chronic gastrointestinal disease to hereditary defects in cobalamin metabolism. Measurement of serum cobalamin concentration, often in combination with serum folate concentration, is routinely performed as a diagnostic test in clinical practice. While the detection of hypocobalaminemia has therapeutic implications, interpretation of cobalamin status in dogs can be challenging. The aim of this review is to define hypocobalaminemia and cobalamin deficiency, normocobalaminemia, and hypercobalaminemia in dogs, describe known cobalamin deficiency states, breed predispositions in dogs, discuss the different biomarkers of importance for evaluating cobalamin status in dogs, and discuss the management of dogs with hypocobalaminemia.

Hereditary defect of cobalamin metabolism with adolescence onset resembling multiple sclerosis: 41-year follow up in two cases

The cblC defect is the most common inborn error of cobalamin (Cbl) metabolism. Clinical severity and presentation of the cblC defect ranges from death to mild disability. Only 71 cases of late-onset cblC defect have been described in the literature. We provide the 41-year follow up of two siblings with a late-onset cblC defect, first described after initial diagnosis in 1996. While one of the siblings showed initial symptoms resembling multiple sclerosis with a good response to corticosteroids, the other sister showed only subclinical signs of the disease. The course of the first case was characterized by a severe deterioration and intensive-care therapy after respiratory failure. After diagnoses and Cbl treatment, the patient survived and showed a pronounced improvement of the symptoms. Both sisters have an active life and gave birth to healthy children. The reason for the initial improvement after corticosteroids could not be explained by the classical metabolic pathways of Cbl. Recent studies have suggested that Cbl plays an important role as a regulator of the balance between neurotrophic and neurotoxic factors in the central and peripheral nervous system (CNS and PNS). This first long-term follow up revealed that ultra-high-dose intramuscular Hydroxocobalamin (OH-Cbl) treatment can effectively protect patients from disease progression. It underlines the importance of diagnostic vigilance and laboratory work up even in cases without typical hematologic signs of Cbl deficiency. Cbl-related diseases are often a chameleon and must always be considered in the differential of demyelinating diseases of the PNS and CNS. The case supports the theory that it is not only the classical biochemical pathways that play a key role in Cbl deficiency, especially with regard to neurological symptoms.

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.

A Rare Cause of Pancytopenia in an Exclusively Breastfed Infant

Vitamin B12 (B12) deficiency in infancy can present with nonspecific symptoms. We report a 5-month old exclusively breastfed full-term infant with emesis, lethargy, progressive pancytopenia, hemolysis, hypofibrinogenemia, elevated lactate dehydrogenase and a hypercellular bone marrow with dyserythropoiesis. The B12 level in the serum was undetectable. The infant's lethargy resolved within 48 hours of intramuscular B12 injection, followed by rapid improvement of pancytopenia. The asymptomatic mother had a normal hemoglobin and mean corpuscular volume, but undetectable B12 level and positive antibodies to intrinsic factor, consistent with pernicious anemia masked by folate supplementation in the mother but causing symptoms in her infant.

Neurological disorders in vitamin B12 deficiency

The review discusses thesteps of vitamin B12 metabolism and its role in maintaining of neurological functions. The term "vitamin B12 (cobalamin)" refers to several substances (cobalamins) of a very similar structure. Cobalamin enters the body with animal products. On the peripherу cobalamin circulates only in binding with proteins transcobalamin I and II (complex cobalamin-transcobalamin II is designated as "holotranscobalamin"). Holotranscobalamin is absorbed by different cells, whereas transcobalamin I-binded vitamin B12 - only by liver and kidneys. Two forms of cobalamin were identified as coenzymes of cellular reactions which are methylcobalamin (in cytoplasm) and hydroxyadenosylcobalamin (in mitochondria). The main causes of cobalamin deficiency are related to inadequate intake of animal products, autoimmune gastritis, pancreatic insufficiency, terminal ileum disease, syndrome of intestinal bacterial overgrowth. Relative deficiency may be seen in excessive binding of vitamin B12 to transcobalamin I. Cobalamin deficiency most significantly affects functions of blood, nervous system and inflammatory response. Anemia occurs in 13-15% of cases; macrocytosis is an early sign. The average size of neutrophils and monocytes is the most sensitive marker of megaloblastic hematopoiesis. The demands in vitamin B12 are particularly high in nervous tissue. Hypovitaminosis is accompanied by pathological lesions both in white and gray brain matter. Several types of neurological manifestations are described: subacute combined degeneration of spinal cord (funicular myelinosis), sensomotor polyneuropathy, optic nerve neuropathy, cognitive disorders. The whole range of neuropsychiatric disorders with vitamin B12 deficiency has not been studied well enough. Due to certain diagnostic difficulties they are often regarded as "cryptogenic", "reactive", "vascular» origin. Normal or decreased total plasma cobalamin level could not a reliable marker of vitamin deficiency. In difficult cases the content of holotranscobalamin, methylmalonic acid / homocysteine, and folate in the blood serum should be investigated besides carefully analysis of clinical manifestations.

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.

The Singer's and the Clinician's Perspective on Vitamin B12 Treatment for Vocal Benefits

INTRODUCTION

There is a belief among vocalists that there are voice benefits from vitamin B₁₂ treatment. Yet there are no previous reports regarding vitamin B₁₂ effects on voice.

OBJECTIVES

To assess the prevalence of vitamin B₁₂ use among singers and their beliefs regarding vitamin B₁₂ therapy.

METHODS

Anonymous online survey administered to singers, singing-teachers, speech-language pathologists, and laryngologists.

RESULTS

A total of 192 participants completed the surveys; 128 singers (68 singing-teachers, 30 speech-language pathologists) and 64 laryngologists. Among singers, 12% have perceived voice benefits from vitamin B₁₂ treatment taken for any reason. Four percent used vitamin B₁₂ for voice benefits; all perceived voice benefits as a result. The leading voice benefits were improved stamina, reduced effort, confidence, and control. Nineteen percent of the singers would recommend vitamin B₁₂ treatment to a friend; 15% of the singing-teachers would recommend it to a student. Among laryngologists, 33% been asked by a singer to prescribe vitamin B₁₂ for voice benefits; 9% have prescribed it in the past. Yet only 3% would you recommend it to a patient. When asked "Do you believe vitamin B₁₂ therapy improves vocal performance?" 31% of the singers responded "Yes," compared with none in the laryngologists. When asked "Do you think the singing community believes vitamin B₁₂ therapy improves vocal performance?" 26% of the singers responded "Yes," compared with 53% of the laryngologists (P = 0.0002).

CONCLUSIONS

There is a discrepancy between the singers' and the laryngologists' beliefs regarding vocal benefits perceived by vitamin B₁₂. Blinded randomized trials are required to verify or refute this belief.

Metformin Use and Vitamin B12 Deficiency: Untangling the Association

BACKGROUND

Current evidence linking vitamin B12 deficiency with metformin use is inconsistent. Hence, there is uncertainty regarding the diagnostic approach in this scenario. Furthermore, this possible association has not been studied in the complete spectrum of patients with diabetes.

MATERIALS AND METHODS

We conducted a cross-sectional, controlled study with the objective of assessing differences in serum vitamin B12 levels among patients with and without diabetes with different metformin-treatment regimens. A total of 150 participants were recruited: patients with diabetes (group 1: metformin alone ≥850mg/day, group 2: patients with type 2 diabetes naive to treatment and group 3: metformin ≥850mg/day, in addition to any other oral glucose lowering agent or insulin, or both) and without diabetes (group 4: polycystic ovary syndrome or group 5: healthy individuals). Serum vitamin B12, folate levels and complete blood counts were obtained for the entire population. Methylmalonic acid and homocysteine were obtained for patients when vitamin B12 levels were found to be borderline or low.

RESULTS

When patients with or without diabetes were compared, no significant difference was found in relation to their vitamin B12 levels (517.62 versus 433.83; P = 0.072). No difference in vitamin B12 levels was found among participants with metformin use and metformin naive participants (503.4 versus 462.3; P = 0.380).

CONCLUSIONS

Irrespective of metformin use, no significant difference in the serum levels of vitamin B12 was observed, both in patients with and without diabetes. In the light of the body of evidence and the results of this study, a universal recommendation for vitamin B12 deficiency screening cannot be made.

Antivitamin B12 Inhibition of the Human B12 -Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate

B₁₂ antivitamins are important and robust tools for investigating the biological roles of vitamin B₁₂ . Here, the potential antivitamin B₁₂ 2,4-difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co-C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B₁₂ -processing enzyme CblC with high affinity (K_D =130 nm) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B₁₂ and CblC, as well as into the organization of GSH and a base-off cobalamin in the active site of this enzyme.

Overexpression of Transcobalamin 1 is an Independent Negative Prognosticator in Rectal Cancers Receiving Concurrent Chemoradiotherapy

Objective: Neoadjuvant concurrent chemoradiotherapy (CCRT) is an increasingly common therapeutic strategy for locally advanced rectal cancer, but stratification of risk and final outcomes remain a major challenge. Transcobalamin 1 (TCN1), a vitamin B12 (cobalamin)-binding protein, regulates cobalamin homeostasis. High expression of TCN1 have been reported in neoplasms such as breast cancer and hepatocellular carcinoma. However, little is known about the relevance of TCN1 to rectal cancer receiving CCRT. This study examined the predictive and prognostic impact of TCN1 expression in patients with rectal cancer following neoadjuvant CCRT. Methods: Through data mining from a published transcriptome of rectal cancers (GSE35452), we identified upregulation of TCN1 gene as the most significantly predicted poor response to CCRT among ion transport-related genes (GO:0006811). We evaluated TCN1 immunohistochemistry and performed an H-score analysis on endoscopic biopsy specimens from 172 rectal cancer patients receiving neoadjuvant CCRT followed by curative surgery. Expression levels of TCN1 were further correlated with clinicopathologic features, therapeutic response, tumor regression grade (TRG) and survivals including metastasis-free survival (MeFS), disease-specific survival (DSS) and recurrent-free survival (LRFS). Results: TCN1 overexpression was significantly related to advanced post-treatment tumor (T3, T4; p<0.001) and nodal status (N1, N2; p<0.001), vascular invasion (p=0.003) and inferior tumor regression grade (p < 0.001). In survival analyses, TCN1 overexpression was significantly associated with shorter DSS (p<0.0001), MeFS (p=0.0002) and LRFS (p=0.0001). Furthermore, it remained an independent prognosticator of worse DSS (p=0.002, hazard ratio=3.344), MeFS (p=0.021, hazard ratio=3.015) and LRFS (p=0.037, hazard ratio=3.037) in the multivariate comparison. Conclusion: Overexpression of TCN1 is associated with poor therapeutic response and adverse outcomes in rectal cancer patients receiving CCRT, justifying the potential prognostic value of TCN1 in rectal cancer receiving CCRT.

Reversal of isolated 20q deletion with vitamin B12 replacement in a patient with pernicious anaemia

Severe vitamin B₁₂ deficiency is well known to cause morphological alterations in bone marrow. In rare instances, these myelodysplastic and megaloblastic changes can coexist with cytogenetic abnormalities. Here, we report a case of a 38-year-old African-American woman with pernicious anaemia, who was found to have an isolated 20q deletion and which resolved after vitamin B₁₂ replacement. We also discuss various mechanisms in which vitamin B₁₂ deficiency can lead to chromosomal abnormalities. A literature review is also performed to evaluate various other chromosomal aberrations associated with B₁₂ deficiency.

Renal thrombotic microangiopathy in patients with cblC defect: review of an under-recognized entity

Methylmalonic aciduria and homocystinuria, cobalamin C (cblC) type, is the most common genetic type of functional cobalamin (vitamin B₁₂) deficiency. This metabolic disease is characterized by marked heterogeneity of neurocognitive disease (microcephaly, seizures, developmental delay, ataxia, hypotonia) and variable extracentral nervous system involvement (failure to thrive, cardiovascular, renal, ocular) manifesting predominantly early in life, sometimes during gestation. To enhance awareness and understanding of renal disease associated with cblC defect, we studied biochemical, genetic, clinical, and histopathological data from 36 patients. Consistent clinical chemistry features of renal disease were intravascular hemolysis, hematuria, and proteinuria in all patients, with nephrotic-range proteinuria observed in three. Renal function ranged from normal to renal failure, with eight patients requiring (intermittent) dialysis. Two thirds were diagnosed with atypical (diarrhea-negative) hemolytic uremic syndrome (HUS). Renal histopathology analyses of biopsy samples from 16 patients revealed glomerular lesions typical of thrombotic microangiopathy (TMA). Treatment with hydroxycobalamin improved renal function in the majority, including three in whom dialysis could be withdrawn. Neurological sequelae were observed in 44 % and cardiopulmonary involvement in 39 % of patients, with half of the latter group demonstrating pulmonary hypertension. Mortality reached 100 % in untreated patients and 79 and 56 % in those with cardiopulmonary or neurological involvement, respectively. In all patients presenting with unclear intravascular hemolysis, hematuria, and proteinuria, cblC defect should be ruled out by determination of blood/plasma homocysteine levels and/or genetic testing, irrespective of actual renal function and neurological status, to ensure timely diagnosis and treatment.

Metformin Treatment and Homocysteine: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The aim of this systematic review is to assess whether metformin could change the concentration of serum homocysteine (Hcy) with and without simultaneous supplementation of B-group vitamins or folic acid. A literature search was conducted in PubMed, EmBase, and Cochrane Central Register of Controlled Trials (CENTRAL) to identify randomized controlled trials (RCTs) reporting the concentration of serum Hcy in metformin-treated adults. Meta-analysis was applied to assess the association between metformin and the changes of Hcy concentration. Twelve publications were included in this study. In the overall analysis, metformin administration was not statistically associated with the change of Hcy when compared with the control treatment (mean difference (MD), 0.40 μmol/L; 95% confidence interval (CI), -0.07~0.87 μmol/L, p = 0.10). In the subgroup analysis, metformin was significantly associated with an increased concentration of Hcy in the absence of exogenous supplementation of folic acid or B-group vitamins (MD, 2.02 μmol/L; 95% CI, 1.37~2.67 μmol/L, p < 0.00001), but with a decreased concentration of serum Hcy in the presence of these exogenous supplementations (MD, -0.74 μmol/L; 95% CI, -1.19~-0.30 μmol/L, p = 0.001). Therefore, although the overall effect of metformin on the concentration of serum Hcy was neutral, our results suggested that metformin could increase the concentration of Hcy when exogenous B-group vitamins or folic acid supplementation was not given.

Application of a new version of GA-RBF neural network for simultaneous spectrophotometric determination of Zn(II), Fe(II), Co(II) and Cu(II) in real samples: An exploratory study of their complexation abilities toward MTB

The current study for the first time is devoted to the application of whole space genetic algorithm-radial basis function network (wsGA-RBFN) method to determine the content micro minerals of Zn(2+), Fe(2+), Co(2+) and Cu(2+) based on their complexes formation with methylthymol blue (MTB) spectrophotometrically in various pharmaceutical products and vegetable samples. Advantage of wsGA-RBFN compared to GA-RBFN is that centers can be located in any point of the samples spaces. Initially, the parameters controlling behavior of the system were investigated and optimum conditions were selected. Then, an exploratory analysis of complex systems was carried out by chemometrics approaches such as SVD, EFA, MCR-ALS and RAFA. The optimal parameters and conditions for constructing the proposed model of wsGA-RBFN were obtained from processing the data set of synthetic samples. Finally, wsGA-RBFN was successfully applied to the simultaneous determination of Zn(2+), Fe(2+), Co(2+) and Cu(2+) in tomato, white cabbage, red cabbage and lettuce and pharmaceutical products included iron, zinc, multi complete and B12 ampoule.

Deciphering the Transcriptional Response Mediated by the Redox-Sensing System HbpS-SenS-SenR from Streptomycetes

The secreted protein HbpS, the membrane-embedded sensor kinase SenS and the cytoplasmic response regulator SenR from streptomycetes have been shown to form a novel type of signaling pathway. Based on structural biology as well as different biochemical and biophysical approaches, redox stress-based post-translational modifications in the three proteins were shown to modulate the activity of this signaling pathway. In this study, we show that the homologous system, named here HbpSc-SenSc-SenRc, from the model species Streptomyces coelicolor A3(2) provides this bacterium with an efficient defense mechanism under conditions of oxidative stress. Comparative analyses of the transcriptomes of the Streptomyces coelicolor A3(2) wild-type and the generated hbpSc-senSc-senRc mutant under native and oxidative-stressing conditions allowed to identify differentially expressed genes, whose products may enhance the anti-oxidative defense of the bacterium. Amongst others, the results show an up-regulated transcription of genes for biosynthesis of cysteine and vitamin B₁₂, transport of methionine and vitamin B₁₂, and DNA synthesis and repair. Simultaneously, transcription of genes for degradation of an anti-oxidant compound is down-regulated in a HbpSc-SenSc-SenRc-dependent manner. It appears that HbpSc-SenSc-SenRc controls the non-enzymatic response of Streptomyces coelicolor A3(2) to counteract the hazardous effects of oxidative stress. Binding of the response regulator SenRc to regulatory regions of some of the studied genes indicates that the regulation is direct. The results additionally suggest that HbpSc-SenSc-SenRc may act in concert with other regulatory modules such as a transcriptional regulator, a two-component system and the Streptomyces B₁₂ riboswitch. The transcriptomics data, together with our previous in vitro results, enable a profound characterization of the HbpS-SenS-SenR system from streptomycetes. Since homologues to HbpS-SenS-SenR are widespread in different actinobacteria with ecological and medical relevance, the data presented here will serve as a basis to elucidate the biological role of these homologues.

Multivitamin Use and Serum Vitamin B12 Concentrations in Older-Adult Metformin Users in REGARDS, 2003-2007

Metformin, an insulin-sensitizing drug, is a first line treatment for type 2 diabetes. Long-term use of metformin has been associated with subsequent reductions in vitamin B12 concentrations. The objective of our study was to determine whether metformin use is associated with lower serum vitamin B12 concentrations in older adults, and whether concurrent use of multivitamins modifies this association. We examined 2,510 participants aged 50 years and over, participating in the national population-based Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study. Multivariable linear and logistic regression models were used to assess associations between multivitamin use and serum vitamin B12 concentrations. We estimated adjusted odds ratios (aOR)s and confidence intervals (CI)s. Results were stratified by three metformin/diabetes sub-groups: 1) participants with diabetes who were metformin users; 2) participants with diabetes who were not metformin users; and 3) participants without diabetes. We found that diabetic metformin users had significantly lower geometric mean serum B12 concentrations (409 pmol/L) than the group with diabetes not taking metformin (485 pmol/L; P<0.01), and the group without diabetes (445 pmol/L; P = 0.02). The geometric mean serum B12 concentrations were greater for multivitamin users (509 pmol/L) compared to those who did not use multivitamins (376 pmol/L; p<0.01). Among the participants with diabetes who were on metformin therapy, multivitamin use was associated with geometric mean serum vitamin B12 concentrations that were 50% (or 161 pmol/L) higher, compared to those not using multivitamins. Among metformin users, multivitamin use was associated with lower prevalence of combined low and borderline vitamin B12 concentrations (aOR = 0.14; 95% CI = 0.04, 0.54) compared to those not using multivitamins. In conclusion, metformin use was associated with lower geometric mean serum vitamin B12 concentrations among diabetic older adults compared to their counterparts. Concurrent multivitamin use may potentially protect against low or borderline vitamin B12 concentrations in long-term metformin users. Additional research is needed to further examine this association as low or borderline vitamin B12 concentrations can be preventable, or treatable if detected at an early stage, in long-term metformin users.

Systemic mastocytosis: A cohort study on clinical characteristics of 136 patients in a large tertiary centre

BACKGROUND

Systemic mastocytosis (SM) is a rare heterogeneous disease which is characterized by the aberrant proliferation of mast cells. It can be divided into various subtypes with different phenotypes and prognoses. Here, we report on the clinical characteristics of 136 SM patients.

METHODS

A retrospective cohort study was conducted from January 2009 to September 2014 in a large tertiary centre in The Netherlands. We included all patients who fulfilled WHO criteria for SM. Data were collected from electronic patient files.

RESULTS

A total of 124 patients had indolent SM (ISM) (91.2%), 7 had aggressive SM (ASM) (5.1%) and 5 had SM with associated hematological non-mast cell lineage disease (SM-AHNMD) (3.7%). There was no progression from ISM to advanced SM subtypes, but 1 patient with ASM developed chronic myelocytic leukemia 2years after diagnosis. The average time to diagnosis for the whole population was 8.1years (range, 0-49years). The most frequent triggers for work-up-skin involvement, anaphylaxis and osteoporosis-were characterized by an interval to diagnosis of 10.9, 2.9 and 7.5years, respectively. A total of 32 patients (23.5%) had a serum tryptase levels below the cutoff value of 20ng/mL at the time of diagnosis, but these patients did not have significant differences in clinical phenotype.

CONCLUSIONS

SM comprises a wide spectrum of signs and symptoms and its often atypical presentation can delay the establishment of the diagnosis substantially. Skin involvement, anaphylaxis and unexplained osteoporosis should trigger analysis for mastocytosis. A normal serum tryptase does not exclude the diagnosis of SM.

Effect of vitamin B12 deficiency on olfactory function

BACKGROUND

Vitamin B12 plays a major role in the maintenance of central and peripheral nervous systems. Vitamin B12 deficiency may affect the spinal cord, brain, optic nerve, and peripheral nerve functions; however, the effect of vitamin B12 deficiency on olfactory function has not been studied, so our study aimed to investigate that.

METHODS

Thirty-nine patients with low vitamin B12 levels and 34 controls were included in the study. All participants had detailed otorhinolaryngological examinations and laboratory tests. The Sniffin' Stick test was used for analysis of olfactory function. The 2 groups were compared for smell test results. Correlations of smell test results with demographic and laboratory data were investigated in the vitamin B12-deficient group.

RESULTS

The threshold discrimination identification scores were (mean ± standard deviation) 28.04 ± 5.58 and 35.10 ± 2.84 in the vitamin B12-deficient and control groups, respectively (p < 0.001). In the vitamin B12-deficient group, hyposmia and anosmia were evident in 56.4% and 5.1% of the patients, respectively, but no subjects in the control group had olfactory dysfunction (p < 0.001). Correlation analysis showed that age and odor identification score showed a negative correlation (p < 0.001); however, there was a positive correlation between threshold, discrimination and identification (TDI) score and vitamin B12 levels.

CONCLUSION

In this study, we showed for the first time that olfactory dysfunction may be present in patients with vitamin B12 deficiency. Apart from a negative correlation of age with odor identification score, none of the other parameters studied showed correlations with olfactory dysfunction.

Severe but Not Moderate Vitamin B12 Deficiency Impairs Lipid Profile, Induces Adiposity, and Leads to Adverse Gestational Outcome in Female C57BL/6 Mice

Vitamin B12 deficiency is widely prevalent in women of childbearing age, especially in developing countries. In the present study, through dietary restriction, we have established mouse models of severe and moderate vitamin B12 deficiencies to elucidate the impact on body composition, biochemical parameters, and reproductive performance. Female weanling C57BL/6 mice were fed for 4 weeks: (a) control AIN-76A diet, (b) vitamin B12-restricted AIN-76A diet with pectin as dietary fiber (severe deficiency group, as pectin inhibits vitamin B12 absorption), or (c) vitamin B12-restricted AIN-76A diet with cellulose as dietary fiber (moderate deficiency group as cellulose does not interfere with vitamin B12 absorption). After confirming deficiency, the mice were mated with male colony mice and maintained on their respective diets throughout pregnancy, lactation, and thereafter till 12 weeks. Severe vitamin B12 deficiency increased body fat% significantly, induced adiposity and altered lipid profile. Pregnant dams of both the deficient groups developed anemia. Severe vitamin B12 deficiency decreased the percentage of conception and litter size, pups were small-for-gestational-age and had significantly lower body weight at birth as well as weaning. Most of the offspring born to severely deficient dams died within 24 h of birth. Stress markers and adipocytokines were elevated in severe deficiency with concomitant decrease in antioxidant defense. The results show that severe but not moderate vitamin B12 restriction had profound impact on the physiology of C57BL/6 mice. Oxidative and corticosteroid stress, inflammation and poor antioxidant defense seem to be the probable underlying mechanisms mediating the deleterious effects.

Mechanistic studies of the reactions of the reduced vitamin B12 derivatives with the HNO donor Piloty's acid: further evidence for oxidation of cob(I)alamin by (H)NO

There is accumulating evidence for the existence of HNO in biological systems. Compared with NO (˙NO), much less is known about the chemical and biochemical reactivity of HNO. Kinetic and mechanistic studies have been carried out on the reaction between the vitamin B12-derived radical complex cob(II)alamin (Cbl(II)˙, Cbl(II)) with the widely used HNO donor Piloty's acid (PA). A stoichiometry of 1 : 2 Cbl(II) : PA was obtained and PA decomposition to HNO and benzenesulfinate (C6H5SO2(-)) is the rate-determining step. No evidence was found for nitrite (Griess assay), ammonia (Nessler's test) or NH2OH (indooxine test) in the product solution, and it is likely that HNO is instead reduced to N2. A mechanism is proposed in which reduction of Cbl(II) by (H)NO results in formation of cob(I)alamin (Cbl(I)(-)) and ˙NO. The Cbl(I)(-) intermediate is subsequently oxidized back to Cbl(II) by a second (H)NO molecule, and Cbl(II) reacts rapidly with ˙NO to form nitroxylcobalamin (NOCbl). Separate studies on the reaction between Cbl(I)(-) and PA shows that this system involves an additional step in which Cbl(I)(-) is first oxidized by (H)NO to Cbl(II), which reacts further with (H)NO to form NOCbl, with an overall stoichiometry of 1 : 3 Cbl(I)(-) : PA. Experiments in the presence of nitrite for both systems support the involvement of a Cbl(I)(-) intermediate in the Cbl(II)/PA reaction. These systems provide the second example of oxidation of cob(I)alamin by (H)NO.

Low Cobalamin Levels as Predictors of Cobalamin Deficiency: Importance of Comorbidities Associated with Increased Oxidative Stress

BACKGROUND

Cobalamin (B12) deficiency can lead to irreversible neurocognitive changes if unrecognized. Screening involves measurement of serum cobalamin levels, but the sensitive metabolic indicators of cobalamin deficiency, methylmalonic acid (MMA) and homocysteine (HCys), may be normal when cobalamin values are low and elevated when cobalamin values are normal. Because cobalamin is inactivated by oxidation, the relationship between these metabolites and comorbidities associated with increased oxidative stress (oxidant risks) in subjects with low and low-normal cobalamin levels was studied.

METHODS

A retrospective record-review was conducted of community-dwelling adults evaluated for cobalamin deficiency during a 12-year period with serum cobalamin values in the low (≤ 200 pg/mL; n = 49) or low-normal (201-300 pg/mL; n = 187) range and concurrent measurement of MMA.

RESULTS

When "No" oxidant risk was present, elevated MMA (>250 nmol/L) and HCys (>12.1 μmol/L) values occurred in 50% and 30% of subjects, respectively (P <.01). In contrast, when "Three or More" oxidant risks were present, mean MMA and HCys values were significantly higher, and elevated MMA and HCys values occurred in 84% and 78% of these subjects, respectively (P ≤.012). Pharmacologic doses of cyanocobalamin significantly decreased metabolite values in ≥ 94% of treated subjects.

CONCLUSION

In subjects with low or low-normal cobalamin values, metabolic evidence of cobalamin deficiency is more frequent when 3 or more oxidant risks are present. Thus, defining a low serum cobalamin level to screen for cobalamin deficiency may be a "moving target" due to the variable presence and severity of often subtle, confounding clinical conditions in individual subjects.

New insights into the metabolic and nutritional determinants of severe combined immunodeficiency

Human mutations in MTHFD1 have recently been identified in patients with severe combined immunodeficiency (SCID). SCID results from inborn errors of metabolism that cause impaired T- and B-cell proliferation and function. One of the most common causes of SCID is adenosine deaminase (ADA) deficiency, which ultimately inhibits DNA synthesis and cell division. MTHFD1 has been shown to translocate to the nucleus during S-phase of the cell cycle; this localization is critical for synthesis of thymidyate (dTMP or the “T” base in DNA) and subsequent progression through the cell cycle and cell proliferation. Identification of MTHFD1 mutations that are associated with SCID highlights the potential importance of adequate dTMP synthesis in the etiology of SCID.

[The use of neurobion in neurological practice]

Vitamins are actively involved in many metabolic processes of the nervous system. Their deficit may cause severe and, sometimes, irreversible consequences. Mechanisms of the therapeutic effects of the vitamin B complex neurobion are considered. Results of the studies on the efficacy and safety of neurobion in patients with polyneuropathies, including those caused by diabetes mellitus, pain syndromes of origin (skeletal/muscle pain, trauma etc) are presented. The necessity of using neurobion in treatment of a wide spectrum of nervous system diseases is emphasized.

Local Administration of Methylcobalamin and Lidocaine for Acute Ophthalmic Herpetic Neuralgia: A Single-Center Randomized Controlled Trial

OBJECTIVES

To determine the therapeutic efficacy of combined methylcobalamin and lidocaine for acute ophthalmic herpetic neuralgia (AOHN).

METHODS

Based on the onset, patients with AOHN (n = 98) were randomly allocated into groups A (≤ 3 days) and B (4 to 7 days) and then subdivided into control (A0, B0; received intramuscular methylcobalamin in addition to local lidocaine injection) and treatment (A1, B1; received local injection of the methylcobalamin and lidocaine combination for 14 days) groups. Treatment efficacy was assessed based on rash healing time, alteration of pain intensity, and interference with quality of life. Multilevel modeling and survival analysis were performed.

RESULTS

The time (hours) to start and full opening of the affected eye and the time (hours) to start and full crusting were significantly reduced in both treatment groups (P < 0.05 vs. controls). The mean pain scores in A1 (2.6 ± 0.7) and B1 (1.2 ± 0.8) decreased significantly compared with those in A0 (7.0 ± 1.7) and B0 (5.6 ± 1.9), and the difference between the two therapeutic strategies significantly increased over time. The median minimum intervention time was 6 days in B1 and 11 days in A1. The incidence of postherpetic neuralgia (PHN) was 2.04% at 3 months.

CONCLUSIONS

Methylcobalamin combined with lidocaine mediated detumescence and improved cutaneous healing of the affected area, as well as a significant and sustained analgesic effect on AOHN. The incidence of PHN was also significantly decreased. Local methylcobalamin intervention within 4 to 7 days of onset may be an effective therapeutic option for AOHN.

Antivitamins B12--A Structure- and Reactivity-Based Concept

B12 -antimetabolites are compounds that counteract the physiological effects of vitamin B12 and related natural cobalamins. Presented here is a structure- and reactivity-based concept of the specific 'antivitamins B12 ': it refers to analogues of vitamin B12 that display high structural similarity to the vitamin and are 'locked chemically' to prevent their metabolic conversion into the crucial organometallic B12 -cofactors. Application of antivitamins B12 to healthy laboratory animals is, thus, expected to induce symptoms of B12 -deficiency. Antivitamins B12 may, hence, be helpful in elucidating still largely puzzling pathophysiological phenomena associated with B12 -deficiency, and also in recognizing physiological roles of B12 that probably still remain to be discovered.