Pharmacokinetic profiles of methylcobalamin in rats after multiple administration routes by a simple LC-MS/MS assay with a small volume of plasma.

Methylcobalamin (MBL) is a vitamin B12 coenzyme and is effective for treating peripheral neuropathies. Little is known about pharmacokinetics (PK) of MBL in animals, we have developed a simple assay for MBL by using only 0.01 mL of plasma for PK of MBL in rats. Under minimal light exposure (<5 lx), MBL was extracted by a simple protein precipitation using methanol and detected by liquid chromatography with tandem mass spectrometry. MBL in rat plasma at 20-10,000 ng/mL was quantified using only 0.01 mL of plasma. Relative error and relative standard deviation met the acceptance criteria in reproducibility assessments, indicating the robustness of the assay. PK of MBL was evaluated after intravenous, intramuscular, and subcutaneous administration. PK of MBL was dose proportional at 5-20 mg/kg in both intramuscular and subcutaneous administrations. Bioavailability after the two dosing routes was complete (ca. 100 %). The incurred sample reanalysis also supported that the assay is robust. The established assay was successfully applied to PK studies in rats to find that MBL showed high bioavailability after intramuscular and subcutaneous administrations.

A Noble Metal Substitution Leads to B12 Cofactor Mimicry by a Rhodibalamin.

In mammals, cobalamin is an essential cofactor that is delivered by a multitude of chaperones in an elaborate trafficking pathway to two client enzymes, methionine synthase and methylmalonyl-CoA mutase (MMUT). Rhodibalamins, the rhodium analogs of cobalamins, have been described as antimetabolites due to their ability to inhibit bacterial growth. In this study, we have examined the reactivity of adenosylrhodibalamin (AdoRhbl) with two key human chaperones, MMACHC (also known as CblC) and adenosyltransferase (MMAB, also known as ATR), and with the human and Mycobacterium tuberculosis MMUT. We demonstrate that while AdoRhbl binds tightly to all four proteins, the Rh-carbon bond is resistant to homolytic (on MMAB and MMUT) as well as heterolytic (on MMACHC) rupture. On the other hand, MMAB catalyzes Rh-carbon bond formation, converting rhodi(I)balamin in the presence of ATP to AdoRhbl. We report the first crystal structure of a rhodibalamin (AdoRhbl) bound to a B12 protein, i.e., MMAB, in the presence of triphosphate, which shows a weakened but intact Rh-carbon bond. The structure provides insights into how MMAB cleaves the corresponding Co-carbon bond in a sacrificial homolytic reaction that purportedly functions as a cofactor sequestration strategy. Collectively, the study demonstrates that while the noble metal substitution of cobalt by rhodium sets up structural mimicry, it compromises chemistry, which could be exploited for targeting human and bacterial B12 chaperones and enzymes.

The structure of the rat vitamin B12 transporter TC and its complex with glutathionylcobalamin.

Vitamin B12 (cobalamin or Cbl) functions as a cofactor in two important enzymatic processes in human cells, and life is not sustainable without it. B12 is obtained from food and travels from the stomach, through the intestine, and into the bloodstream by three B12-transporting proteins: salivary haptocorrin (HC), gastric intrinsic factor, and transcobalamin (TC), which all bind B12 with high affinity and require proteolytic degradation to liberate Cbl. After intracellular delivery of dietary B12, Cbl in the aquo/hydroxocobalamin form can coordinate various nucleophiles, for example, GSH, giving rise to glutathionylcobalamin (GSCbl), a naturally occurring form of vitamin B12. Currently, there is no data showing whether GSCbl is recognized and transported in the human body. Our crystallographic data shows for the first time the complex between a vitamin B12 transporter and GSCbl, which compared to aquo/hydroxocobalamin, binds TC equally well. Furthermore, sequence analysis and structural comparisons show that TC recognizes and transports GSCbl and that the residues involved are conserved among TCs from different organisms. Interestingly, haptocorrin and intrinsic factor are not structurally tailored to bind GSCbl. This study provides new insights into the interactions between TC and Cbl.

The Utility of Oral Vitamin B1 and Mecobalamin to Improve Corneal Nerves in Dry Eye Disease: An In Vivo Confocal Microscopy Study.

Our purpose is to demonstrate the changes in cornea nerve parameters and symptoms and signs in dry eye disease (DED) patients after oral vitamin B1 and mecobalamin treatment. In this randomized double-blind controlled trial, DED patients were randomly assigned to either the treatment group (oral vitamin B1 and mecobalamin, artificial tears) or the control group (artificial tears). Corneal nerve parameters via in vivo confocal microscopy (IVCM), DED symptoms, and signs were assessed at baseline and 1 and 3 months post-treatment. In total, 398 eyes from 199 patients were included. In the treatment group, there were significant improvements in corneal nerve length, width, and neuromas, the sign of conjunctival congestion score (CCS), symptoms of dryness, pain, photophobia, blurred vision, total symptom score, and OSDI (OSDI) at 1/3 months post-treatment (all p < 0.05). Patients who received vitamin B1 and mecobalamin showed greater improvement in CCS, dryness scores at 1 month (p < 0.05), corneal fluorescein staining (CFS) (p = 0.012), photophobia (p = 0.032), total symptom scores (p = 0.041), and OSDI (p = 0.029) at 3 months. Greater continuous improvement in CFS (p = 0.045), dryness (p = 0.033), blurred vision (p = 0.031) and total symptom scores (p = 0.023) was demonstrated at 3 months than at 1 month post-treatment in the treatment group. We found that oral vitamin B1 and mecobalamin can improve corneal nerve length, width, reflectivity and the number of neuromas in IVCM, thereby repairing epithelial cells and alleviating some ocular symptoms. Thus, vitamin B1 and mecobalamin are potential treatment options for patients with DED.

Effects of Infrared Combined with Methylcobalamin on the Vibratory Sensory Threshold and Nerve Conduction Velocity of the Lower Extremity in Patients with Diabetic Foot Treatment.

Objective: To investigate the effect of infrared combined with methylcobalamin on the vibratory sensory threshold and lower limb nerve conduction velocity of patients with diabetic foot. Methods: One hundred and six patients with diabetic foot in our hospital from February 2018 to December 2020 were enrolled and divided into the study and control groups. The patients in the control group were given methylcobalamin, and the patients in the research group were treated with infrared light on the basis of the control group. The therapeutic effect, vibration sensory threshold, lower limb nerve conduction velocity, and related biochemical index levels before and after treatment in the two groups were counted. Result: The total effective rate of the study group (94.34%) was significantly higher than that of the control group (81.13%). The left/right lower limb vibration sensation threshold decreased in both groups after treatment, and the study group was lower than that of the control group (P < 0.05). The conduction velocity of the left/right common peroneal nerve and tibial nerve increased in both groups after treatment, and the study group was larger than that of the control group (P < 0.05). The bFGF, VEGF, and APN increased in both groups after treatment. VEGF and APN increased and IL-6 and TNF-α decreased in both groups after treatment, and the study group was better than the control group (P < 0.05). Conclusion: Infrared and methylcobalamin combined treatment of diabetic foot can effectively improve lower extremity nerve conduction velocity and vibration sensory threshold, regulate serum bFGF and VEGF levels, reduce the degree of inflammatory response, and help improve the overall treatment effect.

Stability indicating RP-HPLC method for methylcobalamin determination in different dosage forms: Application to photodegradation kinetics and pH rate profiling.

A stability-indicating RP-HPLC method for methylcobalamin determination was developed. Stress degradation under variable conditions was carried out. Methylcobalamin had pronounced susceptibility to hydrolysis under acidic, alkaline, and photolytic conditions; further study of photolytic degradation kinetics and pH rate profiling over pH range 2-11 was carried out. Photodegradation of methylcobalamin followed zero-order kinetics with half-life 0.99 h equivalent to 1971.53 lux. Methylcobalamin followed pseudo-first-order kinetics upon exposure to acidic and alkaline hydrolysis with highest stability at pH 5 and least stability at pH 2. Optimization of chromatographic conditions was performed using two level full factorial design, and chromatographic analysis was executed using Inertsil column (250 × 4.6 mm, 5 µm) maintained at 25◦ C. Elution was carried out using 25 mM potassium dihydrogen phosphate (pH adjusted with phosphoric acid to 3.8): methanol:acetonitrile (55:35:10, v/v) as mobile phase. The flow rate was 1.0 ml/min. Detection was carried out at 220 nm using diode array detector. The method was validated as per ICH guidelines; the linearity was over concentration range 2-160 µg/ml with coefficient of determination 0.9995. The method was effectively applied for determination of methylcobalamin in Cobalvex ampoule, Cobal tablet, Cobal-F tablet, and Methyltechon oral dissolvable film without interfering from excipients within run time 6 min.

Improvement of the Clinical and Psychological Profile of Patients with Autism after Methylcobalamin Syrup Administration.

(1) Background: Autism, also known as autism-spectrum disorder, is a pervasive developmental disorder affecting social skills and psychological status in particular. The complex etiopathogenesis of autism limits efficient therapy, which leads to problems with the normal social integration of the individual and causes severe family distress. Injectable methylcobalamin was shown to improve the clinical status of patients via enhanced cell oxidative status and/or methylation capacity. Here we tested the efficiency of a syrup form of methylcobalamin in treating autism. (2) Methods: Methylcobalamin was administered daily at 500 µg dose to autistic children and young adults (n = 25) during a 200-day period. Clinical and psychological status was evaluated by parents and psychologists and plasma levels of reduced and oxidized glutathione, vitamin B12, homocysteine, and cysteine were determined before the treatment, and at day 100 and day 200 of the treatment. (3) Results: Good patient compliance was reported. Methylcobalamin treatment gradually improved the overall clinical and psychological status, with the highest impact in the social domain, followed by the cognitive, behavioral and communication characteristics. Changes in the clinical and psychological status were strongly associated with the changes in the level of reduced glutathione and reduced/oxidized glutathione ratio. (4) Conclusion: A high dose of methylcobalamin administered in syrup form ameliorates the clinical and psychological status of autistic individuals, probably due to the improved oxidative status.

Based on proteomics to explore the mechanism of mecobalamin promoting the repair of injured peripheral nerves.

Mecobalamin is commonly used in the adjuvant intervention of various peripheral nerve injuries. Actin cytoskeleton plays a role in the regeneration of myelin and axon. Therefore, the purpose of this study was to explore the possibility of mecobalamin regulating actin cytoskeleton in repairing nerve injury. In this study, a crush injury on the right sciatic nerve of two groups of rats (12 in each group) was established. The control group was only given normal saline (i.g.), and the intervention group was given mecobalamin 1 mg/kg (i.g.). The rats were sacrificed on 28th day and the injured nerves were collected for proteomics. The result shows that regulation of actin cytoskeleton pathway changed significantly. The expression of protein Vav1 was verified by Western blot and immunofluorescence. In the intervention group, the nerve fiber structure was complete, the axons were dense and symmetrical, and the myelin sheath was compact and uniform in thickness. The positive rate of myelin basic protein and ßⅢ-tubulin was higher than that in the control group. The findings of the study show that mecobalamin regulates the actin cytoskeleton in the repair of nerve damage and upregulates Vav1 in the regulation of actin cytoskeleton pathway.

Aerobic photolysis of methylcobalamin: unraveling the photoreaction mechanism.

The photo-reactivity of cobalamins (Cbls) is influenced by the nature of axial ligands and the cofactor's environment. While the biologically active forms of Cbls with alkyl axial ligands, such as methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), are considered to be photolytically active, in contrast, the non-alkyl Cbls are photostable. In addition to these, the photolytic properties of Cbls can also be modulated in the presence of molecular oxygen, i.e., under aerobic conditions. Herein, the photoreaction of the MeCbl in the presence of oxygen has been explored using density functional theory (DFT) and time-dependent DFT (TD-DFT). The first stage of the aerobic photoreaction is the activation of the Co-C bond and the formation of the ligand field (LF) electronic state through the displacement of axial bonds. Once the photoreaction reaches the LF excited state, three processes can occur: namely the formation of OO-CH3 through the reaction of CH3 with molecular oxygen, de-activation of the {Im⋯[CoII(corrin)]⋯CH3}+ sub-system from the LF electronic state by changing the electronic configuration from (dyz)1(dz2)2 to (dyz)2(dz2)1 and the formation of the deactivation complex (DC) complex via the recombination of OO-CH3 species with the de-excited [CoII(corrin)] system. In the proposed mechanism, the deactivation of the [CoII(corrin)] subsystem may coexist with the formation of OO-CH3, followed by immediate relaxation of the subsystems in the ground state. Moreover, the formation of the OO-CH3 species followed by the formation of the {[CoIII(corrin)]-OO-CH3}+ complex stabilizes the system compared to the reactant complex.

Clinical Evaluation and Therapeutic Effects of Combination Treatment with Mecobalamin + Vitamin E in Recurrent Oral Ulcer.

PURPOSE: Recurrent oral ulcer is one of the most prevalent inflammatory ulcerative disorders of the oral mucosa. Due to the indeterminant cause and unpredictable course of the disease, clinical treatment of patients with recurrent oral ulcer is focused on relieving the pain, shortening the course of the disease, and prolonging the intermission period. Numerous chemical and biologic agents have been characterized as beneficial in the treatment of patients with recurrent oral ulcer, but there is currently no definitive therapy available. This study aimed to investigate the clinical effects and tolerability of combined mecobalamin tablets and vitamin E capsules in the treatment of recurrent oral ulcer. METHODS: A total of 58 patients with recurrent oral ulcer admitted to our hospital were allocated to receive mecobalamin tablets + vitamin E soft capsules (test group) or Fe complex enzyme gargle only (control group) (n = 29 per group). Changes in parameters such as pain level, as measured on a 10-point visual analog scale (VAS); ulcer status and number of ulcers; proinflammatory cytokine levels; and quality of life, as measured using SF-36, from before to after treatment were measured. Mean intermission time and mean ulcer healing time were calculated. Total effectiveness rate was also calculated. The occurrences of adverse reactions in the two groups were quantified. FINDINGS: The total intermission time interval was significantly longer, the mean ulcer healing time was considerably shorter, the total number of ulcers was appreciably less, and the total effectiveness rate was significantly greater in the test group compared to the control group (all, P < 0.05). The VAS scores were significantly greater after treatment than before treatment in both the test and control groups (mecobalamin + vitamin E, 2.16 [1.09] vs 7.87 [0.51]; control, 3.72 [1.15] vs 7.94 [0.56]; both, P < 0.05). Interleukin (IL)-8, tumor necrosis factor α, and C-reactive protein levels were appreciably down-regulated in both groups when compared to before treatment. In addition, IL-2 concentration and SF-36 scores were much greater after treatment in the test group with respect to the control group. Levels of IL-8, TNF-α, and CRP were significantly lesser in the test group than in the control group (all, P < 0.05). IMPLICATIONS: The combination of mecobalamin tablets and vitamin E soft capsules was effective in the treatment of recurrent oral ulcer. This combination can be used as an adjunctive therapy, offering effective pain control and improving quality of life in patients with oral ulcers.

The efficacy of acoustic therapy versus oral medication for chronic tinnitus: A meta-analysis.

PURPOSE: To compare the efficacy of acoustic therapy (AT) and drug therapy (DT) for chronic tinnitus. METHODS: We searched Pubmed, ScienceDirect, Chinese Journal Full-text Database (CNKI), Wanfang Database, Chinese Biomedical Literature Database (CBM), Embase, and Cochrane Library from the establishment of the database to December 2019. Meta-analysis was performed on the Tinnitus Handicap Inventory (THI) score and Visual Analogue Scale (VAS) with included literature using Revman 5.3 software. RESULTS: A total of 18 documents were included, including 16 Chinese documents and 2 English documents, with 1774 patients (including 962 patients treated with AT and 812 patients treated with DT). The effect of AT (by the number of cases or ears) is better than that of DT (P < 0.05). After treatment, the THI value of AT was more evident than that of DT (WMD = -4.25, (-13.24, -5.29)). And the VAS value of AT was significantly lower than that of DT (WMD = -0.73, (-1.31, -0.15)). CONCLUSION: Compared with DT, AT can significantly improve the efficacy of tinnitus and reduce the symptoms of tinnitus patients. Clinically, it can vigorously promote the application value of treating tinnitus by sound.

The Clinical Effect of a Combination of Mouse Nerve Growth Factor and Methylcobalamin to Treat Lumbar Disc Herniation with Foot Drop: A Retrospective Cohort Study.

OBJECTIVE: To investigate the clinical effect of mouse nerve growth factor (mNGF) and methylcobalamin (MeCbl) for the treatment of lumbar disk herniation (LDH) with foot drop. METHODS: A total of 46 patients suffering from LDH with foot drop who underwent transforaminal lumbar interbody fusion (TLIF) surgery in our department from January 2015 to December 2017 were retrospectively analyzed. We divided these patients into two groups according to the different postoperative treatment which independently selected by patients after signing informed consent form: one group of 25 patients was treated with MeCbl alone (Group MeCbl), the other group of 21 patients was treated with a combination of mNGF and MeCbl (Group MeCbl+mNGF). Patient demographics, the visual analogue scale (VAS) scores, sensory and muscular strength improvement statistics at 1 week, 4 weeks, 12 weeks, and 12 months postoperatively were recorded. Motor/sensory deficits, sciatica and overall neurological outcome after treatment of MeCbl alone and combination of mNGF and MeCbl were retrospectively analyzed. RESULTS: The follow-up ranged between 12 and 42 months (mean 20.8 months). There were no significant differences between these two groups of patients with respect to sex ratio, age, smoking, diabetes, disease course, section of protruding disc(s), muscular strength of foot dorsiflexion or preoperative visual analogue scale (VAS) score (P > 0.05). The VAS scores of Group MeCbl+mNGF were significantly lower than Group MeCbl at 1 week, 4 weeks, 12 weeks, and 12 months postoperatively (4.32 ± 0.75 vs 5.25 ± 0.79,2.65 ± 0.48 vs 3.42 ± 0.52, 1.72 ± 0.36 vs 2.45 ± 0.39, 1.12 ± 0.22 vs 1.52 ± 0.24, P < 0.05). The effective rates of sensory improvement were significantly higher in Group MeCbl+mNGF compared with Group MeCbl at 12-week/12-month follow-up time point (90.48% vs 52.00%,95.24% vs 68.00%, P < 0.05). The effective rate of muscular strength improvement of the two groups did not differ significantly at 1 week after surgery but exhibited statistically significant differences at subsequent time points (61.90% vs 32.00%, 76.19% vs 44.00%, 80.95% vs 48.00%, P < 0.05). CONCLUSIONS: Application of mNGF had clinical effects on promoting the recovery of neurological function in patients suffering from LDH with foot drop.

Overall Retention of Methyl Stereochemistry during B12-Dependent Radical SAM Methyl Transfer in Fosfomycin Biosynthesis.

Methylcobalamin-dependent radical S-adenosylmethionine (SAM) enzymes methylate non-nucleophilic atoms in a range of substrates. The mechanism of the methyl transfer from cobalt to the receiving atom is still mostly unresolved. Here we determine the stereochemical course of this process at the methyl group during the biosynthesis of the clinically used antibiotic fosfomycin. In vitro reaction of the methyltransferase Fom3 using SAM labeled with 1H, 2H, and 3H in a stereochemically defined manner, followed by chemoenzymatic conversion of the Fom3 product to acetate and subsequent stereochemical analysis, shows that the overall reaction occurs with retention of configuration. This outcome is consistent with a double-inversion process, first in the SN2 reaction of cob(I)alamin with SAM to form methylcobalamin and again in a radical transfer of the methyl group from methylcobalamin to the substrate. The methods developed during this study allow high-yield in situ generation of labeled SAM and recombinant expression and purification of the malate synthase needed for chiral methyl analysis. These methods facilitate the broader use of in vitro chiral methyl analysis techniques to investigate the mechanisms of other novel enzymes.

The effect of Crocin on TFAM and PGC-1α expression and Catalase and Superoxide dismutase activities following cholestasis-induced neuroinflammation in the striatum of male Wistar rats.

Bile secretion is a physiological function that is disrupted following Bile Duct Ligation (BDL) and induces cholestasis. Cholestasis is a bile flow reduction that induces apoptosis, oxidative stress, and inflammation, and alters the expression of genes. Evidence shows the relationship between cholestasis and neuroinflammation. Cholestasis via attenuating mitochondrial biogenesis and anti-oxidant activity can induce neuroinflammation and apoptosis. Mitochondrial transcriptional factor A (TFAM) and Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) are involved in mitochondrial biogenesis, and TFAM, PGC-1α, Catalase (CAT), and Superoxide dismutase (SOD) have a role in upregulating antioxidant pathways. On the other hand, many studies have shown the neuroprotective effects of Crocin, the water-soluble carotenoid of Saffron (Crocus sativus L.). In this study, we aimed to investigate the effect of Crocin on the level of TFAM, PGC-1α, CAT, and SOD following cholestasis-induced neuroinflammation in the rat's striatum. Cholestasis was induced by BDL surgery and administration of Crocin was intraperitoneal, at the dose of 30 mg/kg every day, 24 h after BDL surgery up to thirty days. The results showed that TFAM, PGC-1α, and SOD were decreased following cholestasis; while, CAT was increased. In addition, Crocin restored the effects of cholestasis on the level of TFAM, PGC-1α, and SOD. In conclusion, Crocin may have improvement effects on cholestasis-induced neuroinflammation in the rat's striatum.

A high frequency and geographical distribution of MMACHC R132* mutation in children with cobalamin C defect.

Cobalamin C defect is caused by pathogenic variants in the MMACHC gene leading to impaired conversion of dietary vitamin B12 into methylcobalamin and adenosylcobalamin. Variants in the MMACHC gene cause accumulation of methylmalonic acid and homocysteine along with decreased methionine synthesis. The spectrum of MMACHC gene variants differs in various populations. A total of 19 North Indian children (age 0-18 years) with elevated methylmalonic acid and homocysteine were included in the study, and their DNA samples were subjected to Sanger sequencing of coding exons with flanking intronic regions of MMACHC gene. The genetic analysis resulted in the identification of a common pathogenic nonsense mutation, c.394C > T (R132*) in 85.7% of the unrelated cases with suspected cobalamin C defect. Two other known mutations c.347T > C (7%) and c.316G > A were also detected. Plasma homocysteine was significantly elevated (> 100 µmol/L) in 75% of the cases and methionine was decreased in 81% of the cases. Propionyl (C3)-carnitine, the primary marker for cobalamin C defect, was found to be elevated in only 43.75% of cases. However, the secondary markers such as C3/C2 and C3/C16 ratios were elevated in 87.5% and 100% of the cases, respectively. Neurological manifestations were the most common in our cohort. Our findings of the high frequency of a single MMACHC R132* mutation in cases with combined homocystinuria and methylmalonic aciduria may be proven helpful in designing a cost-effective and time-saving diagnostic strategy for resource-constraint settings. Since the R132* mutation is located near the last exon-exon junction, this is a potential target for the read-through therapeutics.

Glutathione combined with mecobalamin in the treatment of chemotherapy-induced peripheral neuropathy in multiple myeloma: a retrospective clinical study.

BACKGROUND: This study sought to examine the use of glutathione combined with mecobalamin in the prevention and treatment peripheral neuropathy (PN) in multiple myeloma (MM) patients, observe its effectiveness and safety, and explore the risk factors and prognostic factors of chemotherapy-induced peripheral neuropathy (CIPN). METHODS: Patients in the study group were administered 2.4 g of glutathione intravenously once daily 2-3 days before chemotherapy, combined with 500 µg of mecobalamin administered intravenously once every other day until the end of the chemotherapy cycle. Patients who did not use this regimen were selected as a control group. Differences in adverse reactions, treatment efficiency, progression-free survival (PFS), and overall survival (OS) between the two groups were retrospectively analyzed. PFS and OS curves were plotted using the Kaplan-Meier method. The univariate analysis rates were compared using the χ2 test. The multivariate analysis was performed by a logistic regression analysis. The proportional hazard regression model was used for the univariate and multivariate proportional hazards model analyses. RESULTS: The incidence of PN, especially grade 2 and 3 PN, was more decreased in the study group than the control group. The history of diabetes (P=0.032) and the method of bortezomib injection (P=0.043) was found to affect the PN grade. The multivariate logistic regression analysis showed that diabetes was an independent risk factor of PN in MM patients [odds ratio (OR) =3.484, P=0.020]. The Proportional hazards model multivariate analysis showed that extramedullary disease (EMD) [hazard ratio (HR) =2.373, P=0.006] and elevated lactic dehydrogenase (LDH) (HR =1.934, P=0.009) were independent prognostic factors for MM patients. CONCLUSIONS: Glutathione combined with mecobalamin significantly reduced the incidence and severity of CIPN in MM patients, and did not increase the adverse reactions of patients with MM. Diabetes and bortezomib intravenously increased the incidence and severity of PN in patients with MM.

Nitric Oxide Inhibits NF-κB-mediated Survival Signaling: Possible Role in Overcoming TRAIL Resistance.

BACKGROUND/AIM: Chemoresistance is a major consequence of multicycle chemotherapy and can be attributed to constitutive activation of pro-survival signaling pathways. Nitric oxide is a ubiquitous signaling molecule which has been shown to inhibit several pathways involved with survival signaling in cancer cells. We have previously demonstrated the anti-tumor activity of a nitric oxide-donor, nitrosylcobalamin (NO-Cbl), mediated by increased expression of tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) and its receptors in human tumors. We also demonstrated that a functional Apo2L/TRAIL receptor is necessary for the induction of cell death by NO-Cbl and the Apo2L/TRAIL death receptor DR4 (TRAIL R1) is S-nitrosylated. The aim of the study was to examine the effects of nitric oxide (NO) on nuclear factor kappa B (NF-κB) and determine whether nitric oxide could sensitize drug-resistant melanomas to Apo2L/TRAIL via inhibition of NF-κB or inhibitor kappa B kinase (IKK). MATERIALS AND METHODS: Antiproliferative effects of NO-Cbl and Apo2L/TRAIL were assessed in malignant melanomas and non-tumorigenic melanocyte and fibroblast cell lines. Athymic nude mice bearing human melanoma A375 xenografts were treated with NO-Cbl and Apo2L/TRAIL. Apoptosis was measured by the TUNEL assay. The activation status of NF-κB was established by assaying luciferase reporter activity, the phosphorylation status of IκBα, and in vitro IKK activity. RESULTS: NO-Cbl sensitized Apo2L/TRAIL-resistant melanoma cell lines to growth inhibition by Apo2L/TRAIL, but had minimal effect on normal cell lines. NO-Cbl and Apo2L/TRAIL exerted synergistic anti-tumor activity against A375 xenografts. NO-Cbl suppressed Apo2L/TRAIL- and TNF-α-mediated activation of a transfected NF-κB-driven luciferase reporter. NO-Cbl inhibited IKK activation, characterized by decreased phosphorylation of IκBα. CONCLUSION: NO-Cbl treatment rendered Apo2L/TRAIL-resistant malignancies sensitive to the anti-tumor effects of Apo2L/TRAIL in vitro and in vivo. The use of nitric oxide to inhibit NF-κB and potentiate the effects of chemotherapeutic agents, such as Apo2L/TRAIL, represents a promising anti-cancer combination based on recent clinical investigations of anti-TRAIL antibodies for cancer treatment strategies.

Comparison of sublingual and intramuscular administration of vitamin b12 for the treatment of vitamin b12 deficiency in children

Abstract Background: In most countries, contrary to some disadvantages, such as pain, relatively higher cost, and poor adherence to treatment, intramuscular (IM) route is still the primary treatment method for Vitamin B12 (VB12) deficiency. In recent years, because of these difficulties, new treatment methods are being sought for VB12 deficiency. Objectives: We aimed to compare sublingual (SL) and IM routes of VB12 administration in children with VB12 deficiency and to compare the efficacy of methylcobalamin and cyanocobalamin therapy in these children. Methods: This retrospective study comprised 129 patients with VB12 deficiency (serum Vitamin 12 level ≤ 200 pg/mL) aged 5-18 years. Based on the formulations of Vitamin 12, we divided the patients into three treatment groups as IM cyanocobalamin, SL cyanocobalamin, and SL methylcobalamin. Results: After Vitamin 12 therapy, serum Vitamin 12 levels increased significantly in all patients, and there was a statistically significant difference between the treatment groups (p < 0.05). Conclusions: SL cyanocobalamin and methylcobalamin were found as effective as IM cyanocobalamin for children with Vitamin 12 deficiency in correcting serum Vitamin 12 level and hematologic abnormalities.

Light Mediated Properties of a Thiolato-Derivative of Vitamin B12.

Vitamin B12 derivatives (Cbls = cobalamins) exhibit photolytic properties upon excitation with light. These properties can be modulated by several factors including the nature of the axial ligands. Upon excitation, homolytic cleavage of the organometallic bond to the upper axial ligand takes place in photolabile Cbls. The photosensitive nature of Cbls has made them potential candidates for light-activated drug delivery. The addition of a fluorophore to the nucleotide loop of thiolato Cbls has been shown to shift the region of photohomolysis to within the optical window of tissue (600-900 nm). With this possibility, there is a need to analyze photolytic properties of unique Cbls which contain a Co-S bond. Herein, the photodissociation of one such Cbl, namely, N-acetylcysteinylcobalamin (NACCbl), is analyzed based on density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The S0 and S1 potential energy surfaces (PESs), as a function of axial bond lengths, were computed to determine the mechanism of photodissociation. Like other Cbls, the S1 PES contains metal-to-ligand charge transfer (MLCT) and ligand field (LF) regions, but there are some unique differences. Interestingly, the S1 PES of NACCbl contains three distinct minima regions opening several possibilities for the mechanism of radical pair (RP) formation. The mild photoresponsiveness, observed experimentally, can be attributed to the small gap in energy between the S1 and S0 PESs. Compared to other Cbls, the gap shown for NACCbl is neither exactly in line with the alkyl Cbls nor the nonalkyl Cbls.