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31.
32.
The purpose of this research was to encapsulate superoxide dismutase (SOD) and catalase (CAT) in biodegradable microspheres
(MS) to obtain suitable sustained protein delivery. A modified water/oil/water double emulsion method was used for poly(D,L-lactide-co-glycolide)
(PLGA) and poly(D,L-lactide) PLA MS preparation co-encapsulating mannitol, trehalose, and PEG400 for protein stabilization.
Size, morphology, porosity, mass loss, mass balance, in vitro release and in vitro activity were assessed by using BCA protein
assay, scanning electron microscopy, BET surface area, and particle-sizing techniques. In vitro activity retention within
MS was evaluated by nicotinammide adenine dinucleotide oxidation and H2O2 consumption assays. SOD encapsulation efficiency resulted in 30% to 34% for PLAMS and up to 51% for PLGA MS, whereas CAT
encapsulation was 34% and 45% for PLGA and PLAMS, respectively. All MS were spherical with a smooth surface and low porosity.
Particle mean diameters ranged from 10 to 17 μm. CAT release was prolonged, but the results were incomplete for both PLA and
PLGA MS, whereas SOD was completely released from PLGA MS in a sustained manner after 2 months. CAT results were less stable
and showed a stronger interaction than SOD with the polymers. Mass loss and mass balance correlated well with the release
profiles. SOD and CAT in vitro activity was preserved in all the preparations, and SOD was better stabilized in PLGA MS. PLGA
MS can be useful for SOD delivery in its native form and is promising as a new depot system. 相似文献
33.
Glutamate and GABA are the major excitatory and inhibitory neurotransmitters in the CNS. In the retina, it has been shown that glutamate and aspartate and their agonists kainate and NMDA promote the release of GABA. In the chick retina, at embryonic day 14 (E14), glutamate and kainate were able to induce the release of GABA from amacrine and horizontal cells as detected by GABA-immunoreactivity. NMDA also induced GABA release restricted to amacrine cell population and its projections to the inner plexiform layer (E14 and E18). Although aspartate reduced GABA immunoreactivity, specifically in amacrine cells of E18 retinas, it was not efficient to promote GABA release from retinas at E14. As observed in differentiated retinas, dopamine inhibited the GABA release promoted by NMDA and aspartate but not by kainate. Our data show that different retinal sites respond to distinct EAAs via different receptor systems. 相似文献
34.
Guerrini Franca; Lombini Alessandra; Bizarri Mariachiara; Pupillo Paolo 《Journal of experimental botany》1994,45(9):1227-1233
Cell suspension cultures of Beta vulgaris L., treated with calciumchelators or untreated, were used to characterize pyndine nucleotide-dependentdiaphorases of microsomes. The microsomal activity of NADH-dependentduroquinone reductase from cultures treated with 10 mM Na2EGTAfor 24 h increased by a factor of 1.8 with respect to controlmicrosomes, and was mainly associated with particles of d=1.17gml1. NADPH-duroquinone reductase and NADH-ferricyanidereductase activities showed smaller increases. Bacterial protein-lipopolysaccharidecomplexes (prLPS) also promoted the increase of microsomal diaphorases;CaEGTA was Ineffective. EGTA effects on enzymes of supernatantand mitochondria were negligible, although Na2EGTA treatmentinduced cell aggregation and strong acidification of the medium. When microsomes from control cultures were solubilized with1% LPC and fractionated in high-efficiency gel permeation columns(FPLC) the diaphorase activities were found associated to threemajor proteins: (i) NADH-specific quinone reductase (NADH-QR)of 340 kDa; (ii) pyndine nucleotide-nonspecific quinone reductase(NAD(P)H-QR) of 85 kDa also having ferricyanide reductase activity;(iii) NADH-specific ferricyanide reductase (NADH-FCR) of 38kDa. The microsomes from EGTA-treated cells also showed a highlyactive NADH-QR having a larger molecular mass (440 kDa) thanin control cells. NAD(P)H-QR also showed increased activity.We conclude that external Ca2+ chelation induces changes indehydrogenase components in microsomes. Furthermore, prLPS probablyexert part of their effect on plants through Ca2+ chelation. Key words: Beta vulgaris, cell cultures, calcium chelators, diaphorase, NAD(P)H-dehydrogenase, lipopolysaccharide, EGTA, quinone reductase 相似文献
35.
This paper describes the formulation of a biodegradable microparticulate drug delivery system containing clodronate, a bisphosphonate
intended for the treatment of bone diseases. Microspheres were prepared with several poly(D,L-lactide-co-glycolide) (PLGA)
copolymers of various molecular weights and molar compositions and 1 poly(D,L-lactide) (PDLLA) homopolymer by a water-in-oil-in-water
(w/o/w) double emulsion solvent evaporation procedure. Critical process parameters and formulation variables (ie, addition
of stabilizing agents) were evaluated for their effect on drug encapsulation efficiency and clodronate release rate from microparticles
Well-formed clodronate-loaded microspheres were obtained for all polymers by selecting suitable process parameters (inner
water/oil volume ratio 1∶16, temperature-raising rate in the solvent evaporation step 1°C/min, 2% wt/vol NaCl in the external
aqueous phase). Good yields were obtained in all batches of clodronate microspheres (above 60%); drug encapsulation efficiencies
ranged between 49% and 75% depending on the polymer used. Clodronate release from all copolymer microspheres was completed
in about 48 hours, while those from PDLLA microspheres required about 20 days. The change of microsphere composition by adding
a surfactant such as Span 20 or a viscosing agent such as carboxymethylcellulose extended the long-term release up to 3 months.
Clodronate was successfully entrapped in PLGA and PDLLA microspheres, and drug release could be modulated from 48 hours up
to 3 months by suitable selection of polymer, composition, additives, and manufacturing conditions.
Published: July 11, 2001. 相似文献
36.
Leaf hydraulic conductance varies with vein anatomy across Arabidopsis thaliana wild‐type and leaf vein mutants 下载免费PDF全文
Marissa A. Caringella Franca J. Bongers Lawren Sack 《Plant, cell & environment》2015,38(12):2735-2746
Leaf venation is diverse across plant species and has practical applications from paleobotany to modern agriculture. However, the impact of vein traits on plant performance has not yet been tested in a model system such as Arabidopsis thaliana. Previous studies analysed cotyledons of A. thaliana vein mutants and identified visible differences in their vein systems from the wild type (WT). We measured leaf hydraulic conductance (Kleaf), vein traits, and xylem and mesophyll anatomy for A. thaliana WT (Col‐0) and four vein mutants (dot3‐111 and dot3‐134, and cvp1‐3 and cvp2‐1). Mutant true leaves did not possess the qualitative venation anomalies previously shown in the cotyledons, but varied quantitatively in vein traits and leaf anatomy across genotypes. The WT had significantly higher mean Kleaf. Across all genotypes, there was a strong correlation of Kleaf with traits related to hydraulic conductance across the bundle sheath, as influenced by the number and radial diameter of bundle sheath cells and vein length per area. These findings support the hypothesis that vein traits influence Kleaf, indicating the usefulness of this mutant system for testing theory that was primarily established comparatively across species, and supports a strong role for the bundle sheath in influencing Kleaf. 相似文献
37.
Raffaele P. Bonomo Vincenzo Cucinotta Franca D'Alessandro Giuseppe Impellizzeri Giuseppe Maccarrone Enrico Rizzarelli Graziella Vecchio Lorenza Carima Roberto Corradini Giorgio Sartor Rosangela Marchelli 《Chirality》1997,9(4):341-349
A modified β-cyclodextrin bearing a 2-aminomethylpyridine binding site for copper(II) (6-deoxy-6-[N-(2-methylamino)pyridine)]-β-cyclodextrin, CDampy was synthesized by C6-monofunctionalization. The acid-base properties of the new ligand in aqueous solution were investigated by potentiometry and calorimetry, and its conformations as a function of pH were studied by NMR and circular dichroism (c.d.). The formation of binary copper(II) complexes was studied by potentiometry, EPR, and c.d. The copper(II) complex was used as chiral selector for the HPLC enantiomeric separation of underivatized aromatic amino acids. Enantioselectivity in the overall stability constants of the ternary complexes with D- or L-Trp was detected by potentiometry, whereas the complexes of the Ala enantiomers did not show any difference in stability. These results were consistent with a preferred cis coordination of the amino group of the ligand and of the amino acid in the ternary complexes (“cis effect”), which leads to the inclusion of the aromatic side chain of D-Trp, but not of that of L-Trp. In Trp-containing ternary complexes, the two enantiomers showed differences in the fluorescence lifetime distribution, consistent with only one conformer of D-Trp and two conformers of L-Trp, and the latter were found to be more accessible to fluorescence quenching by acrylamide and KI. Chirality 9:341–349, 1997. © 1997 Wiley-Liss, Inc. 相似文献
38.
Gerd Scherer Werner Schempp Carlo Baccichetti Elisabetta Lenzini Franca Dagna Bricarelli Laura Doria Lamba Carbone Ulrich Wolf 《Human genetics》1989,81(3):291-294
Summary Two 46,XY females with tandem duplications of an X short arm segment were studied by cytogenetic and Southern blot analysis. The results show that the duplicated segment in each case included the Xp21.2–Xp22.2 interval, resulting in a double dose of ZFX on the single active X chromosome. The results from our two cases, in conjunction with those reported by other workers, lead us to conclude that the duplication is the reason for the sex inversion. If ZFY and ZFX are indeed sex-determining gene loci, these findings favour a model of sex determination characterized by antagonistic interaction between these genes. 相似文献
39.
Annarosa Selli Franca Crociani Diego Matteuzzi Giorgio Crisetig 《Current microbiology》1986,13(1):33-38
Feedback inhibition of crude and purified extracts of homoserine dehydrogenase and threonine deaminase activities in the genusBifidobacterium was studied. Homoserine dehydrogenase was partially or completely inhibited byl-threonine, and a marked inhibitory effect byl-isoleucine on threonine deaminase was observed. In the speciesBifidobacterium cuniculi high levels ofl-valine reversed the inhibitory effect ofl-isoleucine. The -aminobutyric acid-resistant mutant Ru 326/106 of the speciesB. ruminale, overproducer ofl-isoleucine, had a derepressed homoserine dehydrogenase and a lesser feedback inhibition byl-threonine. Homoserine dehydrogenase appeared to be in bifids specifically NAD dependent. The regulatory mechanisms of aspartate family amino acid biosynthesis in bifidobacteria was discussed. 相似文献