Derivatives of 1-(2-Deoxy-2-fluoro-β-D-arabinofuranosyl)-5-phenyluracil and 5-Benzyluracil. Synthesis and Biological Properties

Abstract

A number of 1-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)uracil and -cytosine nucleosides substituted at the 5 position with a nitrophenyl or nitrobenzyl group were synthesized from 5-phenyl- and 5-benzyluracil via condensation of the fluorinated sugar, followed by nitration. The corresponding amino analogues were also prepared by reduction of the nitro nucleosides. The uracil nucleosides were converted into the corresponding cytosine nucleosides by way of the triazole intermediates. None of these nucleosides exhibited significant activity against herpes simplex virus type 1 in Vero cells. However, cytosine nucleosides containing the o-nitrophenyl, p-nitrophenyl, p-nitrobenzyl or p-aminobenzyl substituent were found to be toxic (even at 1 μM) to uninfected Vero cells, although they were essentially nontoxic in HL-60 cells. The 5′-monophosphates of the uracil nucleosides were inhibitors of the reaction catalyzed by purified Ehrlich ascites carcinoma thymidylate synthase, the 5-phenyluracil nucleotides causing a strong inhibition, competitive vs dUMP, described by the K_i value of 0.01 μM.     

The Microflora of Frozen Passionfruit Nectar Base

A considerable and varied microflora is introduced into passionfruit nectar base under present methods of production. In spite of the great acidity of the nectar base (pH range: 2.8 to 3.2), the high sucrose concentration (approximately 50%), and storage at -20 C, remnants of the microflora persist for a year or longer. During storage, however, there is a steady and gradual decrease, until after about 18 months the microflora is near to extinction. Sample regression lines show straight-line slopes for this diminution in numbers.

A battery of nine media was used to grow a representative aerobic flora. Purified cultures of isolates were identified to genera. Yeasts were the most numerous organisms in all samples, followed by molds, bacteria, and streptomycetes. The bacteria were the first group to disappear during storage. No fecal streptococci or gram-negative bacilli were found in any samples.

     

Nuclear targeting of IGF-1 receptor in orbital fibroblasts from Graves' disease: apparent role of ADAM17

Insulin-like growth factor-1 receptor (IGF-1R) comprises two subunits, including a ligand binding domain on extra- cellular IGF-1Rα and a tyrosine phosphorylation site located on IGF-1Rβ. IGF-1R is over-expressed by orbital fibroblasts in the autoimmune syndrome, Graves' disease (GD). When activated by IGF-1 or GD-derived IgG (GD-IgG), these fibroblasts produce RANTES and IL-16, while those from healthy donors do not. We now report that IGF-1 and GD-IgG provoke IGF-1R accumulation in the cell nucleus of GD fibroblasts where it co-localizes with chromatin. Nuclear IGF-1R is detected with anti-IGF-1Rα-specific mAb and migrates to approximately 110 kDa, consistent with its identity as an IGF-1R fragment. Nuclear IGF-1R migrating as a 200 kDa protein and consistent with an intact receptor was undetectable when probed with either anti-IGF-1Rα or anti-IGF-1Rβ mAbs. Nuclear redistribution of IGF-1R is absent in control orbital fibroblasts. In GD fibroblasts, it can be abolished by an IGF-1R-blocking mAb, 1H7 and by physiological concentrations of glucocorticoids. When cell-surface IGF-1R is cross-linked with (125)I IGF-1, (125)I-IGF-1/IGF-1R complexes accumulate in the nuclei of GD fibroblasts. This requires active ADAM17, a membrane associated metalloproteinase, and the phosphorylation of IGF-1R. In contrast, virally encoded IGF-1Rα/GFP fusion protein localizes equivalently in nuclei in both control and GD fibroblasts. This result suggests that generation of IGF-1R fragments may limit the accumulation of nuclear IGF-1R. We thus identify a heretofore-unrecognized behavior of IGF-1R that appears limited to GD-derived fibroblasts. Nuclear IGF-1R may play a role in disease pathogenesis.     

Effects of supercritical CO2 exposure and depressurization on immobilized lipase activity

Lipozyme IM20 from Novo Nordisk (Denmark) was examined after various treatments. Conditions were chosen to reflect those that would be considered in the design of an industrial process. A two-level factorial design was employed to assess the effects of pressurization/depressurization cycles, rate of depressurization and exposure length. A significant three-factor interaction was observed. Lowest residual activity was observed for runs in which the depressurization rate was 86–89 bar min^–1. Incubation for 12 h also yielded low residual activity but only when exposing the immobilized enzyme to one cycle. The highest residual activity was obtained for immobilized enzymes repeatedly exposed for periods of 12 h (5 times) with a depressurization rate of 4.3 to 4.45 bar min^–1. This effect may be due to the extraction of an inhibiting compound. Tuning process parameters can lead to a seven-fold change in residual activity.     

Aedes aegypti (L.) mosquitoes in Trinidad,West Indies: longevity case studies

Few laboratory and field studies have reported long survival periods for Ae. aegypti females and even fewer have designed experiments to characterize this important life history trait. This study was conducted under laboratory conditions to determine the number of blood meals taken by individual females, the number of eggs laid per individual female, the length of the gonotrophic cycle, and the duration of female survival. The results showed individual females oviposited between 670 and 1,500 eggs throughout their lifetimes, females undergoing large numbers of gonotrophic cycles and surviving up to 224 days. These results are discussed in the context of vector competence, unique alternating high and low oviposition patterns observed after week 14, and resource partitioning/allocation by older Ae. aegypti females after blood feeding.     

Storage solutions: treating lysosomal disorders of the brain

Many neurodegenerative diseases are characterized by the accumulation of undegradable molecules in cells or at extracellular sites in the brain. One such family of diseases is the lysosomal storage disorders, which result from defects in various aspects of lysosomal function. Until recently, there was little prospect of treating storage diseases involving the CNS. However, recent progress has been made in understanding these conditions and in translating the findings into experimental therapies. We review the developments in this field and discuss the similarities in pathological features between these diseases and some more common neurodegenerative disorders.     

Single amino acid substitutions in procollagen VII affect early stages of assembly of anchoring fibrils

Procollagen VII is a homotrimer of 350-kDa pro-alpha1(VII) chains, each consisting of a central collagenous domain flanked by the noncollagenous N-terminal NC1 domain and the C-terminal NC2 domain. After secretion from cells, procollagen VII molecules form anti-parallel dimers with a C-terminal 60-nm overlap. Characteristic alignment of procollagen VII monomers forming a dimer depends on site-specific binding between the NC2 domain and the triple-helical region adjacent to Cys-2634 of the interacting procollagen VII molecules. Formation of the intermolecular disulfide bonds between Cys-2634 and either Cys-2802 or Cys-2804 is promoted by the cleavage of the NC2 domain by procollagen C-proteinase. By employing recombinant procollagen VII variants harboring G2575R, R2622Q, or G2623C substitutions previously disclosed in patients with dystrophic epidermolysis bullosa, we studied how these amino acid substitutions affect intermolecular interactions. Binding assays utilizing an optical biosensor demonstrated that the G2575R substitution increased affinity between mutant molecules. In contrast, homotypic binding between the R2622Q or G2623C molecules was not detected. In addition, kinetics of heterotypic binding of all analyzed mutants to wild type collagen VII were different from those for binding between wild type molecules. Moreover, solid-state binding assays demonstrated that R2622Q and G2623C substitutions prevent formation of stable assemblies of procollagen C-proteinase-processed mutants. These results indicate that single amino acid substitutions in procollagen VII alter its self-assembly and provide a basis for understanding the pathomechanisms leading from mutations in the COL7A1 gene to fragility of the dermal-epidermal junction seen in patients with dystrophic forms of epidermolysis bullosa.     

Cdc5 influences phosphorylation of Net1 and disassembly of the RENT complex

Background  

In S. cerevisiae, the mitotic exit network (MEN) proteins, including the Polo-like protein kinase Cdc5 and the protein phosphatase Cdc14, are required for exit from mitosis. In pre-anaphase cells, Cdc14 is sequestered to the nucleolus by Net1 as a part of the RENT complex. When cells are primed to exit mitosis, the RENT complex is disassembled and Cdc14 is released from the nucleolus.