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Background and purpose: Myelin-producing oligodendrocytes play a key role in supporting normal neuronal function of the mammalian central nervous system (CNS). Formation of myelinating oligodendrocytes from their precursors requires activation and coordination of a set of stage-specific transcriptional regulators that are important for the biosynthesis of myelin components. Olig2 plays an important role in oligodendrocyte differentiation, myelination and remyelination. Some studies indicated the importance of Vitamin B12 in the immunotherapies for MS patients. This study investigated the effects of Vitamin B12 on total protein concentration (TPC) and Olig2 expression in the cerebral cortex. Materials and methods: Thirty mice were divided into three groups (n=10 in each group). The first group received Vitamin B12 injections (50 µg dissolved in normal saline) once a week for three weeks. Normal saline injection was done for the second group and the third group was left without injection as the control group. In this study we investigated the role of vitamin B12 on TPC and Olig2 expression in the cerebral cortex using Bio-Rad protein assay based on the Bradford dye procedure and Western Blot, respectively. Results: The results showed that TPC and Olig2 expression in the cerebral cortex increased in the group injected with vitamin B12 compared with those of the control group. Conclusion: It is believed that vitamin B12 may play a key role in myelination in the CNS by increasing Olig2 expression and thus oligodendrocytes differentiation.

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Background and purpose: Nitrous oxide (N2O) is an anesthetic widely used in operating rooms. Chronic exposure to N2O causes decrease in mental performance, peripheral neuropathy, and polyneuropathy. The aim of this study was to compare neurological complications caused by N2O exposure between operating room staff and other hospital staff.
Materials and methods: In this multicenter cohort study, operating room staff (n=110) and non-operating room staff (n= 224) in Arak Valiasr Hospital and Isfahan Al-zahra Hospital were randomly selected and individually matched. Both groups were examined for neuropathic symptoms and their medical history was recorded. Clinical neurological exams such as Romberg test were used in both groups. Patients with neuropathic sign and symptoms were referred to a neurology clinic to confirm any diagnosis.
Results: The two groups were significantly different in ataxia, numbness, weakness and paresthesia of upper and lower limb, Romberg test score, and levels of Vitamin B12 (P<0.05). No significant differences were observed between the two groups in mean Hemoglobin level, temperature sense, touch and two-point discrimination, stereo gnosis, tandem walking, and plantar and dorsal flexion (P≥ 0.05).
Conclusion: Chronic exposure to nitrous oxide was found to decrease serum vitamin B12 levels and caused neurological symptoms and complications. Therefore, clinical and laboratory evaluations and monitoring of exposure to nitrous oxide is necessary.
 

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Background and purpose: Given the inevitable use of metformin in treatment, the management and possible elevation of cobalamin levels by metformin use should be addressed. However, the reduction in vitamin B12 levels caused by metformin has been mentioned in many studies and books, but there is no suggestion for the concomitant use of vitamin B12 with metformin. This study was conducted with the aim of assessing the association between metformin use and vitamin B12 depletion in type 2 patients
Materials and methods: In this descriptive cross-sectional study, 96 people were randomly selected. Two clinic patients referred to Tankab Hospitals and Imam Sajjad (AS) Ramsar Hospital internal clinic with normal CBC from the beginningwere included in this study. Information was recorded in patient records through paraclinics and interviews. 5 ml of venous blood samples was drawn these patients who had been taking metformin for at least 6 months to determine hemoglobin levels, red blood cell indices including MCV, and vitamin B12 levels. CBC and B12 plasma level were taken.t-tests and analysis of variance, Mann-Whitney and Kruskal-Wallis tests, chi-square tests and logistic regression were used. The software used in this study is IBM-SPSS V.20, and the significance level of the tests is considered to be less than 5%.
Results: In this study, 96 patients were examined. The differences in vitamin B12 levels in diabetic patients taking metformin were borderline significant depending on age (P=0.063). The vitamin B12 level was significantly higher in men than in female patients (P=0.023). There were no statistically significant differences in vitamin B12 levels depending on BMI, Hb level, underlying disease and use of other hypoglycaemic medication (P>0.05). The frequency of vitamin B12 level was significantly lower in diabetic patients taking metformin with normal MCV than in patients with MCV (P=0.012). The frequency of vitamin B12 level was highestin diabetic patients taking 2000 mg metformin per day (13.3%) and lowest in patients taking 500 mg per day, and this difference was statistically significant (P=0.013).
Conclusion: The results show that metformin causes a decrease in vitamin B12 levels in diabetics who take it. Due to the high prevalence of vitamin B12 deficiency caused by metformin and its relationship with dose and duration of use, patients ' serum levels of vitamin B12 should be monitored regularly and, in case of deficiency or symptoms of deficiency, patients should take vitamin B12 supplements to improve the quality of treatment and prevent complications caused by diabetes and metformin.