vitamin-b-12 and Astrocytoma

Astrocytes derived from human brain tissue secreted a single cobalamin (vitamin B12, Cbl) binding protein over a 4 day period in culture. Cycloheximide reversibly inhibited the release, and the binding protein was identified as transcobalamin II (TCII) based on molecular size, reaction with anti-human TCII antiserum, precipitation with 2.0 M ammonium sulfate and its ability to bind radioactive cyanocobalamin. It also enhanced the cellular incorporation of the vitamin. Our data show that cultured cells from human brain synthesize and secrete TCII and suggests that at least some of the TCII known to be present in cerebrospinal fluid may originate from within the central nervous system.

Topics: Astrocytes; Astrocytoma; Brain; Brain Chemistry; Brain Neoplasms; Culture Media; Cycloheximide; Humans; Protein Binding; Transcobalamins; Tumor Cells, Cultured; Vitamin B 12

We reported here 19-year-old man suffering from circadian sleep-wake (S-W) rhythm disturbance after total tumor resection and whole brain irradiation. This 19-year-old man was diagnosed as having astrocytoma in the right temporal lobe by CT scan and angiography at the age of 6 months. After total tumor resection and whole brain irradiation (60Co 60 Gy), he showed profound psychomotor retardation, endocrinologic dysfunction including hypothyroidism and growth hormone deficiency, and sleep-wake rhythm disturbance. At the age of 19, brain MRI revealed asymmetrical low intensity in the hypothalamic region. On endocrinological examination panhypopituitarism due to primary hypothalamic lesion was evident. His S-W rhythm was disturbed showing a dispersed type sleep, i.e., sleep periods were dispersedly distributed throughout the 24 hours. So he showed a lethargic tendency in the daytime. All-day polysomnography revealed abnormal sleep structure such as the absence of sleep spindle and hump, peripheral apnea, snoring and low oxygen saturation. After L-thyroxine supplementation his daily activity improved gradually. The decrease in short time sleep and tendency of a free-running rhythm were observed and oxygen saturation improved remarkably. Peripheral apnea and snoring disappeared. The wakening effect of L-thyroxine administration may be due to improvement of hypothyroidism symptom such as myxoedematous pharynx. In addition, it seems related to the alteration of the central S-W rhythm regulation, because free-running rhythm appeared after L-thyroxine administration. Vitamin B12 (VB12), which has been reported to be effective for sleep-wake rhythm disorders, was not effective for our patient's free-running rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Astrocytoma; Brain Neoplasms; Circadian Rhythm; Cranial Irradiation; Humans; Hypothalamo-Hypophyseal System; Male; Radiation Injuries; Sleep; Thyroxine; Vitamin B 12; Wakefulness

The conversion of cyanocobalamin to adenosyl- and methylcobalamin is impaired in cobalamin-deficient cultured human glial cells. In contrast cultured human skin fibroblasts retained their ability to synthesize coenzyme forms when grown in cobalamin-deficient medium. Cells were pre-conditioned by growing in cobalamin-deficient media for six weeks and then subcultured in medium containing either free or transcobalamin II-bound 57Co-cyanocobalamin. Although both coenzyme levels were low in cobalamin-deficient glial cells, the decrease in methylcobalamin was more marked than that of adenosylcobalamin. Methionine synthase and Cb1 reductase activities were markedly decreased in cobalamin-deficient glial cells but were unchanged in fibroblasts cultured in cobalamin-deficient medium. Our data suggest that in glial cells, cobalamin coenzyme synthesis and function is exquisitely sensitive to short-term cobalamin deprivation. Glial cells apparently synthesize and secrete transcobalamin II since antibodies directed against the transport protein inhibit the uptake of free cobalamin.

Topics: 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; Astrocytes; Astrocytoma; Biological Transport; Cell Line; Cell Line, Transformed; Cobalt Radioisotopes; Humans; Kinetics; Methylmalonyl-CoA Mutase; Neuroglia; Transcobalamins; Vitamin B 12