Synthesis of glycosylated beta-amino hydroxamates as new class of antimalarials

Glycosylated β-amino acids (3–18, 38, 39), obtained by hydrolysis of glycosylated β-amino esters on reaction with hydroxylamine hydrochloride in presence of DIC/DCC afforded glycosyl β-amino hydroxamates (19–34, 40, 41) in fair to good yields. Compounds (19–34, 40, 41) were screened against human malarial parasite Plasmodium falciparum in vitro for their schizontocidal activity. Compounds (19, 24, 26, 28, 40 and 41) exhibited good activity at 2 μg/mL concentrations.     

Structural effects of carbohydrate-containing polycations on gene delivery. 3. Cyclodextrin type and functionalization

Linear cationic beta-cyclodextrin (beta-CD)-based polymers can form polyplexes with plasmid DNA and transfect cultured cells. The effectiveness of the gene delivery and the cellular toxicity has been related to structural features in these polycations. Previous beta-CD polycations were prepared from the cocondensation of 6(A),6(D)-dideoxy-6(A),6(D)-diamino-beta-CD monomers with other difunctionalized monomers such as dimethyl suberimidate (DMS). Here, the type of CD and its functionalization are varied by synthesizing numerous 3(A),3(B)-dideoxy-3(A),3(B)-diamino-beta- and gamma-CD monomers. Both alkyl- and alkoxydiamines are prepared in order to vary the nature of the spacing between the CD and the primary amines in the monomers. These diamino-CD-monomers are polymerized with DMS to yield amidine-based polycations. The nature of the spacer between the CD-ring and the primary amines of each monomer is found to influence both molecular weight and polydispersity of the polycations. When these polycations are used to form polyplexes with plasmid DNA, longer alkyl regions between the CD and the charge centers in the polycation backbone increase transfection efficiency and toxicity in BHK-21 cells, while increasing hydrophilicity of the spacer (alkoxy versus alkyl) provides for lower toxicity. Further, gamma-CD-based polycations are shown to be less toxic than otherwise identical beta-CD-based polycations.     

Effect of Hypoxia on Caspase-3, -8, and -9 Activity and Expression in the Cerebral Cortex of Newborn Piglets

Caspases play an important role in programmed cell death. Caspase-3 is a key executioner of apoptosis, whose activation is mediated by the initiator caspases, caspase-8 and caspase-9. The present study tested the hypothesis that cerebral hypoxia results in increased activation and expression of caspases-3, -8, and -9 in the cytosolic fraction of the cerebral cortex of newborn piglets. To test this hypothesis the activity and expression of caspases-3, -8, and -9 were determined in newborn piglets divided into normoxic and hypoxic groups. Caspase activity was determined spectrofluorometrically using enzyme specific substrates. The expression of caspase protein was assessed by Western blot analysis using enzyme specific antibody. Caspases-3, -8, and -9 activity and expression was significantly higher in the hypoxic group than in the normoxic group. These results demonstrate that hypoxia induces activation and increased expression of both the initiator caspases and the executioner caspase in the cerebral cortex of newborn piglets. We conclude that hypoxia results in stimulation of both the pathways of caspase-3 activation.     

Degradation of phenol and phenolic compounds by a defined denitrifying bacterial culture

Phenol, a major pollutant in several industrial waste waters is often used as a model compound for studies on biodegradation. This study investigated the anoxic degradation of phenol and other phenolic compounds by a defined mixed culture of Alcaligenes faecalis and Enterobacter species. The culture was capable of degrading high concentrations of phenol (up to 600 mg/l) under anoxic conditions in a simple minimal mineral medium at an initial cell mass of 8 mg/l. However, the lag phase in growth and phenol removal increased with increase in phenol concentration. Dissolved CO₂ was an absolute requirement for phenol degradation. In addition to nitrate, nitrite and oxygen could be used as electron acceptors. The kinetic constants, maximum specific growth rate _max; inhibition constant, K _i and saturation constant, K _s were determined to be 0.206 h^–1, 113 and 15 mg phenol/l respectively. p-Hydroxybenzoic acid was identified as an intermediate during phenol degradation. Apart from phenol, the culture utilized few other monocyclic aromatic compounds as growth substrates. The defined culture has remained stable with consistent phenol-degrading ability for more than 3 years and thus shows promise for its application in anoxic treatment of industrial waste waters containing phenolic compounds.     

Evidence that glycoprotein 96 (B2), a stress protein,functions as a Th2-specific costimulatory molecule

After the engagement of Ag receptor, most of the Th cells for their optimal activation require a second (costimulatory) signal provided by the APCs. We demonstrate the isolation and characterization of a 99- to 105-kDa protein (B2), from LPS-activated B cell surface, and its function as a Th2-specific costimulatory molecule. Appearance of B2 as a single entity on two-dimensional gel electrophoresis and as a distinct peak in reverse-phase HPLC ascertains the fact that B2 is homogeneous in preparation. Electron microscopy as well as competitive binding studies reveal that (125)I-labeled B2 specifically binds anti-CD3-activated T cell surface and also competes with its unlabeled form. Internal amino acid sequences of B2 are found to be identical with stress protein gp96. The identity of B2 as gp96 is also revealed by immunological characterization and by confocal microscopic colocalization studies of B2 and gp96 on LPS-activated B cells. Confocal imaging studies also demonstrate that gp96 can be induced on B cell surface without association of MHC molecules. Furthermore, the novel role of gp96 in Th cell proliferation skewing its differentiation toward Th2 phenotype has also been established. Ab-mediated blocking of gp96-induced signaling not only abrogates in vitro proliferation of CD4(+) T cells, but also diminishes the secretion of Th2-specific cytokines. Notably, the expression of CD91 (receptor of gp96/B2) is up-regulated on anti-CD3-activated Th cells and also found to be present on Th1 and Th2 subsets.     

Radiation-induced changes in permeability in unilamellar phospholipid liposomes

Gamma-radiation-induced oxidative damage in unilamellar dipalmitoylphosphatidylcholine liposomes was investigated using a fluorescence technique. Liposomal changes in permeability induced by gamma radiation were monitored by measuring the leakage of pre-encapsulated 6-carboxyfluorescein, and alterations in lipid bilayer fluidity were determined by 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization. The changes in permeability and fluidity in the bilayer were found to be dependent on the radiation dose in a biphasic fashion. The results are interpreted in terms of lipid bilayer fluidization after exposure to doses up to 1 kGy, but rigidization of the bilayer at higher doses. These results indicate a relationship between alterations in permeability and fluidity in the lipid bilayer after irradiation. The vesicles were protected significantly against radiation-induced oxidative damage in the presence of alpha-tocopherol and ascorbic acid. Radiation-induced changes in the permeability of the liposomes after exposure to gamma radiation and their modification by antioxidants indicate the involvement of a free radical mechanism in the production of damage, which may offer new insights in to the modification of cellular radiosensitivity by modulation of membrane damage.     

Effect of berberine and (±)-bicuculline isolated from<Emphasis Type="Italic">Corydalis chaerophylla</Emphasis> on spore germination of some fungi

Berberine and (±)-bicuculline were isolated from roots and leaves, respectively, ofCorydalis chaerophylla. Both were effectivein vitro against spore germination of some plant pathogenic fungi (Alternaria brassicicola, A. brassicae, A. cheiranthi, A. melongenae, A. solani, Colletotrichum musae, C. falcatum, Curvularia penniseti, C. lunata, C. maculans, C. pallescens, Curvularia sp.,Erysiphe pisi, E. cichoracearum, Erysiphe sp.,Fusarium udum, Helminthosporium spiciferum, H. penniseti, H. frumentacei, Heterosporium sp.,Oidium erysiphoides andUstilago cynodontis). Berberine and (±)-bicuculline significantly inhibited spore germination of all the fungi at concentrations of 100–1000 ppm. Berberine was effective against all the fungi at all concentrations; most of the fungi did not germinate at 1000 ppm.H. penniseti conidia did not germinate at any cencentration of (±)-bicuculline.U. cynodontis was the least sensitive fungus at lower concentrations but 800 ppm dose was highly effective.     

Spatial regulation of DELTA expression mediates NOTCH signalling for segmentation of Drosophila legs.

The Notch (N) signalling pathway is recruited for segregation of cell fates in a number of Drosophila tissue types. We show here that N dependent segmentation of Drosophila legs is regulated by a dynamic pattern of expression of its ligand, DELTA (DL). During third larval instar and early stages of pupation, high levels of DL expression is seen in stripes of cells in the leg imaginal discs which later form the proximal borders of leg joints. These domains also displayed heightened Dl enhancer activity. During subsequent stages of pupation, following segmentation of the leg primordium, DL expression becomes uniform throughout these segments barring the joints. We further show that regulatory Dl mutations or mis-expression of DL abolish leg segmentation. Domains of N signalling for segmentation of legs of flies are thus set up by a stringent spatial regulation of expression of its ligand at the segment border. Further, a comparable role of DL in antennal development reveals a common paradigm of DL-N signalling for segmentation of appendages in flies.     

Surface Ultrastructural Studies on Penetration and Infection Process of Colletotrichum gloeosporioides on Mulberry Leaf Causing Black Spot Disease

Unicelled conidia of Colletotrichum gloeosporioides germinated 3 h after inoculation producing single germ tubes. The orientation of the germ tubes and their lateral branches as they grew was towards the open stomata and away from closed stomata. By 24 h post-inoculation, the lateral branches had developed specialized infection vesicles either over the stomata or within the stomatal cavities. The infection vesicles produced primary infection hyphae which entered the leaves through stomatal openings. The disease symptoms became apparent by 6 days post-inoculation when clusters of abundant conidiophores emerged by rupturing the leaf epidermal layer, forming acervuli mostly near the base of idioblasts. The pressure exerted by the emerging conidiophores caused stretching of epidermal layer leading to the widening of the acervuli. The conidia are borne on the tips of the erect conidiophores.