Riboswitches are ligand-binding elements located in 5' untranslated regions of messenger RNAs, which regulate expression of downstream genes. In Listeria monocytogenes, a vitamin B12-binding (B12) riboswitch was identified, not upstream of a gene but downstream, and antisense to the adjacent gene, pocR, suggesting it might regulate pocR in a nonclassical manner. In Salmonella enterica, PocR is ...

INTRODUCTION Vitamin B12 deficiency can result in macrocytic anemia. Neurologic abnormalities of B12 deficiency include sensory deficits, loss of deep tendon reflexes, movement disorders, neuropsychiatric changes and seizures. Segmental involvement of the distal ileum, such as in tuberculosis, can cause vitamin B12 deficiency. To our knowledge, macrocytic anemia with unusual manifestations such...

1. Measurement of the vitamin B12 content of baboon tissues showed that the liver contained the highest concentration, followed by the pituitary, kidney, heart, spleen and pancreas. 2. The dietary vitamin B12 requirement of the baboon for the maintenance of satisfactory body stores was between 1 and 2 mug/d. 3. Satisfactory liver vitamin B12 stores were invariably associated with serum levels a...

True tinnitus is a phantom auditory perception arising from a source or trigger in the cochlea, brainstem, or at higher centers and has no detectable acoustic generator. The most accepted is the famous neurophysiologic model of Jastreboff, which stresses that tinnitus, is a subcortical perception and results from the processing of weak neural activity in the periphery. The aim of this study is ...

There are increasing studies indicating neuroprotective effects for vitamin B12. In the present study, the effect of intracortical microinjection of vitamin B12 was investigated on penicillin-induced epileptiform activity. We also examined the effects of intracortical microinjection of diazepam (a GABA-benzodiazepine receptor agonist) and flumazenil (a GABAbenzodiazepine receptor antagonist) to...

Vitamin B12 (hydroxycobalamin) is endocytosed by mammalian cells as a complex with transcobalamin II and then processed to free B12 in lysosomes. The mechanism by which free B12 becomes available for subsequent cellular metabolism has been uncertain. Lysosomal transport of cyanocobalamin (B12) was examined using membrane vesicles prepared from Percoll gradient purified lysosomes. B12 uptake by ...

AIM Metformin is the most widely used oral hypoglycaemic drug, but it may lower B12 status, which could have important clinical implications. We undertook a systematic review and meta-analysis of the relationship between metformin use and vitamin B12 deficiency in persons with type 2 diabetes. METHODS Electronic database searches were undertaken (1st January 1957-1st July 2013) using the Coch...

OBJECTIVE To estimate the prevalence of vitamin B12 deficiency in adult South Asian patients. DESIGN Retrospective chart review. SETTING Family practice clinic in Toronto, Ont. PARTICIPANTS Records of 988 South Asian patients. INTERVENTION Of 1000 randomly selected records, we found 988 charts. From charts with at least one documented B12 level, we extracted data on age, mean corpuscula...

Vitamin B12 deficiency with macrocytic anemia is a well-known clinical entity. However the clinical importance of the vitamin B12 insufficiency without any hematological abnormality is underestimated in the adult patient population. The aim of this study is to assess frequency of vitamin B12 deficiency with normal complete blood counts (CBC) in adult subjects. Within the 1-year long period, the...

BACKGROUND AND AIMS Studies in South Asian population show that low maternal vitamin B12 associates with insulin resistance and small for gestational age in the offspring. Low vitamin B12 status is attributed to vegetarianism in these populations. It is not known whether low B12 status is associated with metabolic risk of the offspring in whites, where the childhood metabolic disorders are incr...