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AbstractHIV-1 infection is a global epidemic whose treatment is limited majorly by viral resistance and adverse effects. Natural products from algae have been studied for many years, including antiviral, being an alternative to anti-HIV drug design. Since the isolation of natural products can be a hurdle, molecular modeling is an important tool to study these compounds. Herein, structure-activity relationship, molecular docking, and molecular dynamic studies were performed to direct the studies of ten marine natural products with anti-HIV activity. In the structure-activity relationship, descriptors were identified associating the anti-HIV activity of five diterpenes with possible action on the reverse transcriptase allosteric site. These diterpenes were evaluated by molecular docking, and it was identified that only dolabelladienetriol interacted in the allosteric site. Molecular dynamics suggested that the dolabelladienetriol might interfere with the viral RNA binding to HIV-1 RT by inducing a conformational change of the enzyme. Also, in silicoADMET simulations predicts that the dolabelladienetriol present a high potential to be successfully developed as a drug. Thus, applying in silicoapproaches was possible to suggest potential anti-HIV compounds derived from marine natural products.Communicated by Ramaswamy H. Sarma

Coherent x rays can be produced by scattering of laser light by a beam of relativistic electrons, provided that the electron beam is density modulated or the scattering is done at, or near, 90°. Since the coherent scattering is proportional to N2, where N is the number of electrons, and the incoherent scattering is proportional to N, also a modest degree of coherence can substantially increase the x-ray yield. The theory of laser-electron-beam scattering is reviewed and compared with the emission of radiation by an electron beam in an undulator. Examples of the practical implementation of an intense source of coherent x rays are discussed.

Decreased hemoglobin concentration occurs at six weeks of age. Its mechanism is unclear. We studied six infants at six weeks of age and their parents, with the in vitro plasma clot assay for erythroid progenitor cells CFU-E and BFU-E. Serum samples and peripheral blood (PB) mononuclear cells (MNC) were obtained by venipuncture. Bone marrow (BM) aspirate MNC were obtained from a normal adult volunteer. MNC were fractionated into T-cells and non-T-cells by sheep erythrocyte rosetting. Some PB-MNC from each baby were pre-incubated with: a) fresh plasma (FP), b) rabbit complement (RC), c) FP and baby's serum (BS) and d) RC and BS, for one hour at 37°C. All cultures contained 5 × 104cells per micro-well. 1 × 104T-cells were added to some experiments. The baby's PB-MNC produced a mean of 7±2 BFU-E colonies per clot, and 9.5±5 BFU-E when cultured in the presence of BS. Pre-incubation with FP, RC, FP+BS and RC+BS produced 5±1, 4±1, 5.5±2 and 4±2 BFU-E respectively. Adding baby's T-cells to his/her parents' PB-MNC increased the number of BFU-E from 11 to 19. BM-MNC produced a control of 250±10 CFU-E and 30±6 BFU-E per clot. In the presence of BS there were 219±30 CFU-E and 26±8 BFU-E. The addition of BS to cultures of baby's PB-MNC or the pre-incubation of these cells with BS and complement showed no significant inhibition of PB-BFU-E. The baby's T-cells increased the number of PB-BFU-E. Similarly, BM-CFU-E and BM-BFU-E were not inhibited by BS. T-cell suppression of erythropoiesis or serum inhibitors of erythropoiesis, either complement mediated or not, do not explain the physiologic anemia of the newborn.

Down's syndrome is associated with multiple hematologic abnormalities. Newborns with Down's syndrome may develop a myelodys-plastic syndrome akin to leukemia. The incidence of acute leukemia is increased in Down's syndrome. These serious hematologic complications of Down's syndrome may be the reflection of a steady state of compensated dysmyelopoiesis.We studied 28 otherwise healthy individuals 10-25 years of age with Down's syndrome with three easily accessible hematologic parameters: MCV, MPV and NAP. The NAP was performed by the azodye method of Ackerman on peripheral blood smears and a numerical score given. MCV and MPV were measured by the Coulter counter S plus IV. The Down's syndrome population had a MCV of 94.1±3.9 fl ([xmacr ;[plusmn;SD) a MPV of 9.3±0.7 fl and an NAP score of 161±54. The normal controls for the Coulter counter model S plus IV in our labaratory are a MCV 87±7 and a MPV of 8.9±1.5. The NAP score in normals has a mean score of 100±50. Down's syndrome mean values for MCV, MPV and NAP differed from the mean of normal population in our laboratory (p = <0.01, <0.05 and <0.01 respectively). MCV, MPV and NAP are all increased in Down's syndrome.Macrocytosis, both of platelets and red cells with disordered metabolism of white cells suggest a state of disordered hematopoiesis in individuals with Down's syndrome.