Peripheral leukocytes from Epstein-Barr virus (EBV)-seropositive or seronegative normal adults, or human umbilical cord leukocytes infected or not infected with EBV, were directly transplanted into 50 newborn hamsters treated with anti-lymphocyte serum. Lymphoid tumors were produced after a latent period of 10-25 days in 39 animals: 8 of 14 recipients of seropositive donor leukocytes, 2 of 2 recipients of seronegative donor leukocytes, 13 of 15 recipients of EBV-infected cord leukocytes, and 16 of 19 recipients of non-infected cord leukocytes. EBV-determined nuclear antigen-positive human lymphoblastoid cell lines were established in vitro from tumors produced with seropositive donor leukocytes or EBV-infected cord leukocytes but not from tumors produced with seronegative donor leukocytes or non-infected cord leukocytes. The results indicate that EBV is not a prerequisite for in vivo production of tumors but necessary for in vitro establishment of lymphoblastoid cell lines from such tumors.
SummaryThe vitamin B12 levels of cerebrospinal fluid were assayed microbiologically (Lactobacillus leichmannii method) using samples from 44 patients with various neurological disorders, 4 patients with megalo blastic anemia and 34 controls. Twenty-seven controls that did not receive vitamin B12 showed a mean cerebrospinal fluid vitamin B12 level of 21.5pg/ml (range: 0-60). No decrease in cerebrospinal fluid vitamin B12 level was seen in patients with subacute myelo-optico-neuropathy (SMON). High levels of cerebrospinal fluid vitamin B12 were observed only in the patients receiving long term administration of the vitamin. Intrathecal administration of vitamin B12 caused only a slight increase in serum vitamin B12 level after four hours. The existence of a blood brain barrier for vitamin B12 was suggested.
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