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Biomedical subjects

G Giammona

Publications and source records attributed to G Giammona.

At least 37 records · Page 2Linked to original sources
PubMed1996

Preparation and characterization of polyethyl-2-cyanoacrylate nanocapsules containing antiepileptic drugs.

Biocompatible and biodegradable colloidal drug delivery systems can be obtained by means of in situ polymerization of alkylcyanoacrylate. In particular, nanocapsules of polyethylcyanoacrylate (PECA) were prepared by adding the monomer to an organic phase, consisting of Miglyol 812 and an organic solvent (ethanol, acetone or acetonitrile), and subsequently mixing the organic phase with an aqueous phase containing Pluronic F68 at different concentrations. The possible mechanism of formation and the influence of preparation conditions on the quality of nanocapsule formulations were investigated by freeze-fracture electron microscopy and laser light scattering using both the inverse Laplace transform and the standard cumulant analysis for data fitting. High-quality nanocapsule systems were obtained using an aprotic fully water-miscible organic solvent such as acetone. The presence of ethanol led to the formation of both nanospheres and nanocapsules. The concentrations of nonionic surfactant in the aqueous phase of monomer in the organic phase did not influence the kind of colloidal suspension obtained. The oil simply plays the role of monomer support. The diameter of PECA nanoparticles (nanospheres and nanocapsules) ranged from 100 to 400 nm. Three antiepileptic drugs (Ethosuximide, 5,5-diphenyl hydantoin and carbamazepine) were entrapped in PECA nanocapsules. The loading capacity of PECA nanocapsules, prepared using acetone as organic solvent, varied from 1% to 11% (drug/dried material) as a function of the solubility (affinity) of the different drugs with the oil core. This parameter also influenced the release from PECA nanocapsules, which was slower for drugs with a higher affinity for Miglyol 812. By encapsulating the three antiepileptic drugs in the PECA nanocapsules, it was possible to achieve controlled drug release. The mechanism of drug release from PECA nanocapsules was mainly diffusion from the oil core through the intact polymer barrier.

Acetone↗
PubMed1996

Cytarabine release from alpha, beta-poly (N-hydroxyethyl)-DL-aspartamide matrices cross-linked through gamma-radiation.

alpha, beta-Poly (N-hydroxyethyl)-DL-aspartamide solutions were cross-linked through gamma-radiation and the systems obtained were tested as matrices for drug sustained release, using cytarabine as model drug. We performed the characterization of the cross-linked polymer, both drug-loaded and unloaded. through water swelling measurements, scanning electron microscopy and X-ray analysis. Finally, we investigated the in vitro release behaviour of cytarabine.

Chemistry, Pharmaceutical↗
PubMed1995

Pefloxacine mesilate- and ofloxacin-loaded polyethylcyanoacrylate nanoparticles: characterization of the colloidal drug carrier formulation.

The entrapment of fluoroquinolones, perfloxacine mesilate (PFX) and ofloxacin (OFX), in polyalkylcyanoacrylate (PECA) nanoparticles could offer some advantages for their biological application; for examples, increasing their bioavailability, controlling the drug time-release in blood, and reducing the formation of bacterial resistance. To load these two drugs in PECA polymeric bulk, the incorporation or adsorption method was performed. These two methods were capable of influencing nanoparticle size, molecular weight, release profile, and drug-polymer association. The incorporation method, particularly for the OFX system, achieved PECA nanoparticle suspensions with a mean size value three times higher than that obtained in the absence of the drug. In contrast, negligible changes were observed for PFX systems. This preparation process also influenced the nanoparticle storage stability. The molecular weight values of the various nanoparticle preparations were also influenced; that is, the PFX-loaded systems showed an enhancement in the average molecular weight values, whereas a reduction was observed for OFX-loaded systems. The adsorption method showed no particular difference in particle size, molecular weight, and storage stability compared with nanoparticles prepared without the drugs. The nanoparticle loading capacity was higher for the colloidal systems obtained following the incorporation preparation procedure. The release of drug from the nanoparticles was biphasic for both preparation processes. The fluoro-quinolone-loaded nanoparticles showed an enhancement of the antimicrobial activity against standard bacteria strains from 2- to 50-fold compared with the free drugs.

Biological Availability↗
PubMed1995

In vitro release of ketoprofren and ibuprofen from viscoelastic gels.

Gels of viscoelastic type formed by isopropylmyristate, Tween 60 and water are prepared in the presence or not of antiinflammatory agents such as Ketoprofen and Ibuprofen. In vitro release studies evaluated by using an absorption simulator were performed in order to determine the diffusion rate of these drugs from prepared gels. The obtained results showed a higher rate diffusion compared with the release from commercial products containing these drugs.

Elasticity↗
PubMed1993

Magnetic resonance imaging in cervical spinal cord compression.

In patients with cervical spondylotic myelopathy MRI sometimes shows increased signal intensity zones on the T2-weighted images. It has been suggested that these findings carry prognostic significance. We studied 56 subjects with cervical spinal cord compression. Twelve patients showed an increased signal intensity (21.4%) and a prevalence of narrowing of the AP-diameter (62% vs 24%). Furthermore, in this group, there was evidence of a longer mean duration of the symptoms and, in most of the patients, of more serious clinical conditions. The importance of these predisposing factors remains, however, to be clarified since they are also present in some patients without the increased signal intensity.

Adult↗
PubMed1993

[Bio-imaging for the study of organic changes in the C.N.S.: comparison between computerized tomography and magnetic resonance].

Several comparative studies have been carried out in order to evaluate the possible diagnostic superiority of Computed Tomography (C.T.) vs. Magnetic Resonance Imaging (M.R.I.) in different diseases of the Central Nervous System. The present investigation is aimed at critically revising this problem also including the study of patients clinical data as a criterion of choice. A sample of 69 subjects was examined. It was seen that in demyelinative as well as in chronic cerebrovascular diseases M.R.I. should be preferred because of its higher sensitivity and specificity. Concerning specifically chronic cerebrovascular diseases, clinical data can have a more significant role in justifying the choice of M.R.I. C.T., and M.R.I. should be considered as complementary rather than competitive in studying cerebral tumors and spinal cord pathology; the planning of surgical operations, needing a complete evaluation of data, which in these cases are very variable, requires the use of both methods.

Central Nervous System Diseases↗
PubMed1992

Pro-drugs of isoniazid: synthesis and diffusion characteristics of acyl derivatives.

The attachment of various acyl groups to the NH2 function of isoniazid afforded in good yields pro-drugs which were characterized by spectroscopic and analytical methods. The in vitro diffusion of pro-drugs was studied; the transfer rate constants from simulated gastro-intestinal juices to simulated plasma, through artificial wall lipid membranes were defined and compared with those of an equivalent dose of pure isoniazid. The diffusion rate constants were not greatly affected by the length of the substituent chain. All compounds were treated with artificial gastric or intestinal juices. No significant hydrolysis was observed.

Absorption↗
PubMed1992

Trophic action of acetyl-L-carnitine in neuronal cultures.

Daily addition of acetyl-L-carnitine (100 microM) to cultured cerebellar granule cells since the first day of maturation led to an increased rate of expression of D-[3H]aspartate uptake (an established marker of maturation of glutamatergic neurons) and of N-methyl-D-aspartate (NMDA) receptors linked to large conductance ion channels permeable to Ca2+. Acetyl-L-carnitine treatment also increased neuronal survival, as reflected by a greater percentage of cultures retaining functional NMDA receptors after 15 days of maturation. These results support the view that acetyl-L-carnitine exerts neuronotrophic activity and prevents age-dependent neuronal degeneration.

Acetylcarnitine↗
PubMed1989

Synthesis of polymeric derivatives of isoniazid: characterization and in vitro release from a water-soluble adduct with polysuccinimide.

Coupling of isoniazid with polysuccinimide afforded a water-insoluble polymeric pro-drug; by reaction with ethanolamine it was chemically transformed in a water-soluble adduct. The in vitro release of isoniazid from the drug-polymer adduct was studied by using an artificial stomach wall lipid membrane. The transfer rate constant from simulated gastric juice to simulated plasma was defined and compared with that of an equivalent dose of pure drug.

Chemistry, Pharmaceutical↗
PubMed1989

Synthesis of macromolecular prodrugs of procaine, histamine and isoniazid.

The attachment of various drugs bearing -NH2 groups to poly-alpha,beta-aspartic acid as a biodegradable carrier afforded in good yields macromolecular prodrugs which were characterized with respect to composition and drug load by spectroscopic and analytical methods. N-Ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) in an aqueous medium proved to be useful in the attachment reaction. Isoniazid, procaine and histamine were covalently coupled as pendant groups onto poly-alpha,beta-aspartic acid via an amide bond. In principle, controlled release of the aforementioned drugs can be achieved by biodegradation of the polymer or by cleavage of covalently bound polymer-drug conjugates.

Chemical Phenomena↗
PubMed1989

[Carrier polymers. Synthesis of a new multiaspartic hydrazide].

Synthesis of a new polyasparthydrazide obtained from the reaction of polysuccinimide with hydrazine is described. The new polymer is water soluble. Moreover, the presence of - NH2 groups allowed the reaction with drugs bearing certain functional groups. Therefore polyasparthydrazide seems to be a very interesting candidate as a drug carrier.

Aspartic Acid↗
PubMed1985

Generalized and focal dystonic syndromes: possible therapy with salmon calcitonin.

We report that repeated administration of salmon calcitonin (20-40 micrograms daily for 30 days) improves dystonic symptoms in patients affected by idiopathic torsion dystonia, blepharospasm-oromandibular dystonia syndrome or writer's cramp syndrome. These results support the suggestion that calcitonin may act at central level influencing the extrapyramidal motor system.

Adolescent↗
PubMed1984

[Effects of systemic administration of kainic acid on GABAergic and glutaminergic transmission in various areas of the brain].

In the present study that Authors have investigated the effects of systemic injection of kainic acid on aminoacidergic transmission of different rat brain regions. Kainic acid has been used to produce an experimental model of limbic epilepsy characterized by two different phases (KA1 and KA2). Results obtained show a significant decrease of glutamic and aspartic acids (excitatory aminoacids) and glicine and taurine (inhibitory aminoacids) in both phases at hippocampal level. On the contrary GABA concentration seems to be increased.

Animals↗
PubMed1984

Calciotropic hormones as possible modulators of rat extrapyramidal motor system.

In the present study the Authors have investigated the effects of chronic treatment with calcitonin and parathyroid hormone on rat extrapyramidal motor system. Although it seems that calcitonin and parathyroid hormone may act as a neuromodulators at extrapyramidal level by influencing, directly or indirectly, nigro-striatal dopaminergic transmission, the role played by calcium metabolism at peripheral level, is not clear. In order to put light on this matter, different groups of animals were treated with calciotropic hormones plus EDTA, which is a drug that blocks Ca2+ ions, or EDTA alone. The results obtained don't show any change either in nigral GAD activity or apomorphine induced hyperactivity in EDTA injected animals. Furthermore, EDTA doesn't seem to modify the effects of both PTH and ct, as shown by results obtained in animals treated with ct or PTH plus EDTA.

Animals↗
PubMed1984

[Effects of zinc sulfate on limbic motor epilepsy induced by kainic acid].

In the present study the Authors have investigated the effects of chronic pretreatment with injections of Zn++ sulphate solution on kainic acid induced epilepsy, to verify wether or not Zn++ is able to change the epileptiform pattern induced by kainic acid infection. Results obtained show that Zn++ do not produce any significant change in the experimental parameters by us study.

Animals↗
PubMed1983

[Role of the amygdala in the sedation induced by low doses of apomorphine].

In the present study the role of amygdala in the antidepressant action of imipramine is discussed. An animal model of depression is induced, in rats, by systemic injection of low doses of apomorphine. Systemic administration of imipramine prevents, as already reported, apomorphine-induced sedation. The same effect is observed following intra-amygdaloid imipramine administration. On the contrary, local injection of imipramine in frontal cortex or caudate nucleus does not affect apomorphine-induced sedation.

Amygdala↗