Epstein-Barr virus transforms precursor B cells even before immunoglobulin gene rearrangements

The very early stages of the human B-cell differentiation pathway are poorly understood, primarily because of the lack of appropriate permanent cell lines. Epstein-Barr virus (EBV) is a putative human oncogenic virus which transforms human B cells in vitro into continuously proliferating cells. It has been believed that EBV transforms mature B cells, but recently, transformation of immature pre-B-cell lines has been reported, suggesting that EBV might also transform cells much earlier in the B-cell lineage. We report here the establishment of cell lines transformed by EBV at various stages of the B-cell differentiation pathway. Interestingly, two lines showed the complete absence of immunoglobulin synthesis and the lack of immunoglobulin gene rearrangement despite containing EBV genome and surface markers of B cells. Our results indicate that EBV can infect and transform cells of the B lymphocyte lineage even before immunoglobulin gene rearrangement.     

Phase response curve to anisomycin intau mutant hamsters

Administration of the protein synthesis inhibitor, anisomycin, to wild type hamsters produces phase shifts in their circadian rhythms that have similarities to shifts produced by non-photic behavioral stimulation. A mutation that shortens the period of rhythms in hamsters results in altered responsiveness to non-photic input. However, responses of the mutants to anisomycin are unaffected: their phase response curve (PRC) for anisomycin is similar to that of wild types. This suggests that 1) anisomycin is not acting on mechanisms specifically involved in non-photic behavioral phase shifting, and 2) the mutation affects the non-photic input pathway or the pacemaker itself at a point that is upstream from anisomycin's site of action.     

Identical point mutations of PMP-22 in Trembler-J mouse and Charcot-Marie-Tooth disease type 1A.

We have investigated the peripheral myelin protein gene, PMP-22, in a family with Charcot-Marie-Tooth disease type 1A (CMT1A). The DNA duplication commonly found in CMT1A was absent in this family, but strong linkage existed between the disease and the CMT1A marker VAW409R3 on chromosome 17p11.2. We found a point mutation in PMP-22 which was completely linked with the disease. The mutation, a proline for leucine substitution in the first putative transmembrane domain, is identical to that recently found in the Trembler-J mouse. The presence of this PMP-22 defect in this CMT1A family and the location of PMP-22 within the DNA duplication associated with CMT1A suggest that both structural alteration and overexpression of PMP-22 may lead to the disease.     

Lactate dehydrogenase and glutamate dehydrogenase activities in the circumventricular organs of rat brain following neonatal monosodium glutamate

Glutamate (glu) an excitatory neurotransmitter amino acid, is present in high concentrations in the mammalian central nervous system and is the most abundant amino acid in our daily diet. In the present study the activities of lactate dehydrogenase (LDH) and glutamate dehydrogenase (GDH) were evaluated in the circumventricular organs (CVO) of the brain in 25-day-old rats following MSG administration at a dose of 4 mg/g b.wt during the first ten days of life. The results show the LDH activity increased to 265% of that in the control (p<0.001), whereas GDH activity was significantly decreased (p<0.05), The great elevation in LDH, a cytoplasmic marker enzyme, is apparently due to cytoskeletal changes brought about as a consequence of glu toxicity, whereas lowered GDH activity indicates altered glu homostasis in the blood-brain-barrier deficient areas following neonatal exposure to glu.     

3-Amino-3-deoxy-D-glucose: an antibiotic produced by a deep-sea bacterium

Gram-positive bacteria isolated from deep-sea sediments of the Pacific basin showed considerable antibacterial activity. A Bacillus strain, isolated from a sediment sample collected at a depth of 4310 m, was shown to produce 3-amino-3-deoxy-D-glucose, a known antibiotic.     

Hypothalamic tyrosine hydroxylase activity,plasma gonadotropin and prolactin levels after aminooxyacetic acid in ovariectomized rats

Summary Plasma concentrations of gonadotropin, prolactin and hypothalamic tyrosine hydroxylase (TH) activity were measured in ovariectomized rats treated with aminooxyacetic acid (AOAA), a drug which elevates brain GABA levels. Hypothalamic TH activity was significantly increased with a significant decrease in prolactin (Prl) release. Plasma levels of gonadotropins were not modified by AOAA. These results support an inhibitory action of GABA on Prl release possibly mediated through hypothalamic dopamine.Supported by grants from Indian Council of Medical Research (ICMR), New Delhi. RIA kits for the estimation of LH, FSH and Prl were kindly supplied by Dr A.F. Parlow, NIAMDD-NIH, Bethesda, Maryland, USA. GNB is a UGC research fellow.