210 research outputs found
Avversità e Difesa delle colture - Manuale dell'Agronomo (VI edizione)
No full textPrefazione al capitolo: "Le piante coltivate sono soggette a molteplici fattori che interferiscono con il loro sviluppo vegetativo e produttivo e quindi necessitano di opportune strategie di difesa. ....................................
La Società bibliografica italiana 1896-1916: note storiche e inventario delle carte conservate presso la Biblioteca nazionale Braidense.
No full textRokitamycin loaded microparticles based on chitosan for the therapy of amoebic infections.
No full textOBJECTIVES
The aims of this study were: i) to assess the
feasibility of using biodegradable chitosan
microspheres as carriers for controlled release of
rokitamycin (RK), able to improve the antiamoebic
activity of the drug;i ii) to investigate the preparative
parameters for obtaining microspheres based on
chitosan (CH) suitable for ocular or nasal
administration of rokitamycin;ii iii) to verify if it was
possible to maintain microsphere characteristics
suitable for ocular or nasal administration using water
soluble polymers such as new chitosan derivatives,
diethylaminomethyl-(diethyldimethylene ammonium)n
methylchitosans (C7 and C8) or CH salt, chitosan
glutamate (CG);ii iv) to evaluate the influence of
chitosan properties (CH vs CG) on the in vivo
rokitamycin absorption, after nasal administration of
spray dried microspheres.iii
METHODS
Preparation of spray dried microspheres.
Microsphere formulations based on CH or C7 or C8 or
CG were prepared by spray drying (Mini Büchi B-191,
Büchi Laboratoriums-Technik AG, Flawil,
Switzerland) using different drug–polymer ratios (1–3
and 1–4) and starting from feed solutions with diverse
concentrations (1.5%, 1%, 0.5% and 0.25% (w/v)).
Characterisation of Microspheres. Microparticles
prepared were characterised in terms of yield of
production, drug loading and encapsulation efficiency,
particle size, morphology, in vitro drug release, water
uptake, in vitro mucoadhesion, ex vivo drug
permeation, Energy Dispersive X-ray Diffraction
(EDXD) measurements.
Determination of effects of drug and microspheres
on Acanthamoeba growth. Loaded and unloaded CH
microspheres were dispersed in PYG medium and
applied on trophozoite grown in sterile 24-well plates
(Corning). At selected time intervals (3, 4, 7, 9 and 15
days of incubation), amoebas growing in each well
were counted in a Nageotte chamber, using the inverted
microscope.
In vivo RK administration. Nasal administration of
CG and CH microparticles containing RK to each
nostril of the anaesthetized Male Wistar rats was
performed by use of single dose Monopowder P®
insufflators (Valois Dispray). At predetermined times,
blood and liquor samples were collected and analyzed.
Results were compared with those obtained after
intravenous infusion of RK and nasal administration of
RK aqueous suspension.
CONCLUSIONS
The loading of RK into CH microspheres improves
and prolongs the in vitro antiamoebic activity of the
drug.i CH based microspheres with good morphology
and narrow size distribution, able to increase the
dissolution rate of RK, can be obtained by spray drying
using a low concentration of feed solution and 1-4
drug–polymer ratio.ii RK encapsulation into CH
microspheres increases its poor ex vivo permeability
through nasal sheep mucosa. The encapsulation of RK
in C7 and C8 by using the chosen parameters results in
microparticles showing similar or often better
properties than formulations made by CH with respect
to size, in vitro release behaviour and
mucoadhesiveness.ii
Compared with CH particles, CG microspheres
load the drug in amorphous form, leading to the best
improvement of its water solubility. This property, as
well as the rapid water uptake of CG particles,
increases more the release rate of the drug from
microspheres and only after their in vivo nasal
administration, RK goes to the cerebrospinal fluid and
the bloodstream.iii
ACKNOWLEDGEMENTS
This work was supported by MiUR through grant
PRIN05 and Fondazione Banco di Sardegna. The
authors thank “Farmaceutici Formenti S.p.A” and
Valois Pharma for the donation of RK and the powder
insufflators, respectively.
REFERENCES
i Rassu, G., Gavini, E., Mattana, A., Giunchedi, P. Open
Drug Del J, 2, 38-43, 2008.
ii Rassu, G., Gavini, E., Jonassen, H., Zambito, Y., Fogli, S.,
Breschi, MC, Giunchedi, P. J. Pharm. Sci., 98, 4852-4865,
2009.
iii Gavini, E., Rassu, G., Ferraro, L., Generosi, A., Rau, JV.,
Brunetti, A., Giunchedi, P., Dalpiaz, A. J. Pharm. Sci., In
Press
Nose-to-brain delivery
No full textNose-to-brain delivery represents a big challenge. In fact there is a large number of neurological diseases that require therapies in which the drug must reach the brain, avoiding the difficulties due to the blood–brain barrier (BBB) and the problems connected with systemic administration, such as drug bioavailability and side-effects. For these reasons the development of nasal formulations able to deliver the drug directly into the brain is of increasing importance. This Editorial regards the contributions present in the Special Issue “Nose-to-Brain Delivery”
Tabletted polylactide microspheres prepared by a w/o emulsion-spray drying method
No full textNon disponibil
Polyvinylalcohol substituted with triethyleneglycolmonoethylether as a new material for preparation of solid dispersions of hydrophobic drugs
No full textAmong the different methods used to increase the aqueous drug solubility, the preparation of a solid dispersion with a soluble carrier represents an interesting formulative approach. We substituted polyvinylalcohol with triethyleneglycolmonoethylether and obtained a suitable material for the formulation of a solid dispersion of progesterone, by spray-drying. In particular, we evaluated the influence of the polyvinylalcohol substitution degree and the polymer-drug weight ratios in the preparative mixture on the progesterone dissolution rate in the aqueous environment. Copyright © 2002 Elsevier Science B.V
Valutazione della sensibilità di alcuni portinnesti del susino al fitoplasma del "giallume europeo"
No full textLa ricerca ha individuato sei differenti portinnesti di susino con lo scopo di valutare la loro sensibilità d il loro comportamento rispetto all'infezione con il fitoplasma del giallume europeo delle drupacee (ESFYP). A tale proposito i sei portinnesti sono stati innestati con la cv. Friar ed inoculati mediante inserzioni di tessuto (chip-budding) con materiale proveniente da piante di susino infette da ESFYP.
I risultati ottenuti dopo 5 anni confermano la sensibilità di portinnesti derivati da P. persicae (Cadaman-Avimag), mentre interessante sembra la tolleranza all'infezione del Mirocal e del Mirabolano 29C; in particolare quest'ultimo portinnesto ha manifestato negli anni in prova (5) buona capacità vegetativa, e produttiva nonostante la presenza di sintomi della malattia, confermando così le caratteristiche di tolleranza già conosciute dei genotipi di P. cerasifera nei confronti di questa malattia
Elementi di Virologia Vegetale
No full textIl testo si compone di 10 capitoli, i cui contenuti, esposti in maniera chiara ed esaustiva, sono arricchiti da un elevato numero di tabelle ed illustrazioni esplicative. I primi 2 capitoli riguardano gli aspetti generali della natura e della struttura dei fitovirus, nonchè l'inquadramento sistematico e la nomenclatura.
I 3 capitoli che seguono descrivono le carateristiche molecolari e le strategie di espressione dei genomi virali, le proprietà genetiche ed il ciclo replicativo, mentre il sesto è dedicato ai meccanismi di diffusione nell'ospite dei complessi replicativi virali, sia da cellula a cellula che a lunga distanza.
Il settimo descrive le diverse modalità di trasmissione dei virus da una pianta all'altra: per contatto, propagazione vegetativa, seme, polline, e, in particolare, per vettori ed è seguito da una trattazione degli agenti subvirali (viroidi ed RNA satelliti) che infettano le piante. I capitoli nono e decimo affrontano con dovizia di particolari i metodi di rilevamento ed identificazione di fitovirus e viroidi e gli interventi di lotta contro le virosi delle piante
Erodible perforated coated matrix for extended release of drugs
No full textA new oral modified release system exibiting an in vitro constant release rate has been designed and prepared. The system consists of an erodible matrix core with a central hole and is partially covered with an impermeable polymeric film. The perforated core is made of a low viscosity hydroxypropylmethylcellulose (HPMC); metoprolol tartrate and benfluorex were used as model drugs. The inner hole surface is the only releasing surface of the system. This system can be prepared by using both conventional tabletting and film coating processes
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