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G Sandri

Publications and source records attributed to G Sandri.

At least 19 recordsLinked to original sources
PubMed2006

Prevalence of home artificial nutrition in Italy in 2005: a survey by the Italian Society for Parenteral and Enteral Nutrition (SINPE).

AIM: To determine the prevalence (cases per million inhabitants) of home artificial nutrition (HAN), enteral (HEN) and parenteral (HPN), in Italy, grouped according to administrative regions, patient age and primary disease, and to analyze the impact both of the presence of an HAN regional regulation and of demographic characteristics. METHODS: In April 2005, the Regional Coordinators of the Italian Society for Parenteral and Enteral Nutrition (SINPE) recorded all the ongoing cases of HAN using a structured questionnaire and were asked to estimate the representativeness of the collected sample with respect to the total expected HAN. RESULTS: A total of 6955 cases of HAN (93.5% adults, 6.5% pediatric patients < or = 18 years) were recorded in 16 of the 20 Italian regions (80% of the Italian population; sample representativeness 78%). HAN prevalence 152.6 (83.9% HEN, 16.1% HPN); the HAN range among the regions was: prevalence 28.1-519.8; oncological disease 13.8-75.7%, neurological disease 15.5-79.9%, intestinal failure 1.3-14.0%. An HAN regulation was present in 11 regions. A positive association (P=0.012) was found between the number of years since the regulation was issued and the HAN prevalence, and also between the % neurological patients and the population density (P=0.130) and the % inhabitants > or = 75 years (P=0.040). CONCLUSIONS: The need for HAN regards a great number of patients throughout the country; there are substantial differences between the regions with respect to both the prevalence and the use of HAN in various disease categories. A specific regulation may favor the development of HAN.

Adult↗
PubMed2006

Histological evaluation of buccal penetration enhancement properties of chitosan and trimethyl chitosan.

The aim of the present work was to compare the penetration enhancement properties of chitosan hydrochloride (HCS) both as a polymeric solution and as a nanoparticulate system with that of trimethyl chitosan hydrochloride (TMC) on buccal mucosa. The hydrophilic high molecular weight fluorescein isothiocyanate dextran (FD4; 4400 Da) was used as a macromolecule model. The mechanism involved in the HCS (solution and nanoparticles) and TMC solution penetration enhancement was investigated on pig buccal mucosa, characterized by having stratified epithelium and lacking in tight junctions. The permeation/penetration of FD4 and the change in morphology and histology of the mucosa after contact with the polymers were assessed: the experiments were performed ex-vivo by applying the formulations on excised porcine buccal tissue. For the morphology and the histology studies, the epithelial cell layers from freshly excised pig buccal mucosa were analysed with light microscopy by means of routine histopathology analysis (haematoxylin and eosin staining and Toluidine blue staining) and immunohistochemistry reactions. The organization of desmosomal junctions was assessed by means of an immunochemical reaction on desmosomes and transmission electron microscopy. Confocal laser scanning microscopy (CLSM) was used to find evidence of the location of FD4 in the tissue. Furthermore, the increase of the FD4 apparent permeability coefficient was quantified by means of Franz diffusion cells using isolated buccal epithelium to demonstrate the penetration enhancement properties of the polymer systems. Morphological analysis, performed by light microscopy, transmission electron microscopy and CLSM, suggests a similar mechanism of penetration enhancement for both HCS and TMC solutions and for HCS nanoparticles. Such a mechanism probably involves a repackaging of the epithelial cells up to the basal membrane and a partial disarrangement of desmosomes. The cell viability and the nuclear integrity indicated on the semi-thin section stained with Toluidine blue and by CLSM analysis, respectively, suggest that HCS as a polymer solution and a nanoparticulate system, and TMC polymer solution, do not cause cell damage. Trimethyl chitosan and chitosan nanoparticulate systems were able to increase FD4 permeation across buccal epithelium to a greater extent than the chitosan solution.

Administration, Oral↗
PubMed2004

Does computation provide a model for creativity? An epistemological perspective in neuroscience.

In 1939 Alan Turing, a major scholar in the field of mechanical computation, described a system whose computational power was beyond that of a discrete, finite state machine (Turing Machine). The composition of this system was likely the first example of what is now called an hybrid computational system. Since then, development of neural networks and brain automata has made aware that forms of computation might exist that are likely to go beyond Turing's limits. Natural systems, like the central nervous system in Mammals and man, are likely to use such a type of computation, especially to perform highly integrating activities, like feedback controls and mental creative processes. The latter are usually understood as processes that involve infinitary procedures, ending up in a complex information network, the computational maps, in which both digital, Turing-like computation and continuous, analog forms of calculus are expected to occur. Pictorial representation may be a fruitful example, mostly metaphorical, to analyze the use of this hybrid forms of computation by higher order computational maps, and the possible role of these types of computational processes in painting creativity is briefly analyzed in comparing 15th vs 16th century Renaissance Art. An open challenge for neuroscience in the 21st century is to clarify whether a hybrid neural learning network might represent a reasonable clue to scientifically interpret the theme of "creativity".

Art↗
PubMed2000

Lipoperoxidation damage of spermatozoa polyunsaturated fatty acids (PUFA): scavenger mechanisms and possible scavenger therapies.

The lipid metabolism in sperm cells is important both as one of the main sources for energy production and for cell structure. The double leaflets of the membrane should be considered not simply as a passive lipid film, but as a very specialized structure. The complete maturation of the sperm cell membrane is attained after testicular lipid biosynthetic processes and after passage through the epididymis. A special composition of membrane phospholipids, rich in polyunsaturated fatty acids (PUFA), and the different composition of sperm and immature germ cell membrane are described and discussed. Testis germ cells as well as epididymal maturing spermatozoa are endowed with enzymatic and non-enzymatic scavenger systems to prevent lipoperoxidative damage. Catalase, superoxide dismutase and GSH-dependent oxidoreductases are present in variable amounts in the different developmental stages. Phospholipid hydroperoxide GSH peroxidase (PHGPx) activity and alpha tochopherol of epididymal spermatozoa are considered in detail. Their distribution and roles in caput and cauda epididymal sperm cells are discussed. Seminal plasma also has a highly specialized scavenger system that defends the sperm membrane against lipoperoxidation and the degree of PUFA insaturation acts to achieve the same goal. Systemic predisposition and a number of pathologies can lead to an anti-oxidant/pro-oxidant disequilibrium. Scavengers, such as GSH, can be used to treat these cases as they can restore the physiological constitution of PUFA in the cell membrane. The results of GSH therapy are presented and discussed.

Animals↗
PubMed1998

Antioxidant systems in rat epididymal spermatozoa.

Mammalian caput and cauda epididymidal spermatozoa exhibit diverse stages of maturation, and their plasma membrane shows diverse composition and stability levels, thus enabling these spermatozoa to undergo the acrosomal reaction after transit through the epididymis. As a result, the study of antiperoxidative mechanisms is quite relevant, since epididymal spermatozoa must be properly protected against agents such as reactive oxygen species, which can impair the complex maturation process. We considered activities of certain enzymes (glutathione peroxidase [GPx], phospholipid hydroperoxide glutathione peroxidase [PHGPx], glutathione reductase [GR], superoxide dismutase [SOD], and catalase [CAT]) and the vitamin E content in isolated rat caput and cauda epididymidal spermatozoa. The results indicate that caput epididymidal sperm have significantly greater PHGPx (3.5x), GPx (2.4x), and SOD (1.7x) activities, as well as a greater amount of vitamin E (3.8x). There were no detectable differences in the GR and CAT activities of caput and cauda epididymidal spermatozoa. The substantial drop in PHGPx activity during epididymal transit is discussed in relation to an additional function of this enzyme: the use of caput sperm protamines as a sulfhydryl substrate. In vitro peroxidation of the two sperm populations by the free radical generator (azo-initiator) 2,2'-azobis(2-amidinopropane) dihydrochloride revealed that only about 13% of the vitamin E content of the caput epididymidal spermatozoa was consumed, which contrasts with the greater consumption (about 70%) of the vitamin in cauda epididymidal spermatozoa. Selective inhibition of PHGPx, SOD, or CAT did not change this picture. The higher susceptibility of cauda epididymidal spermatozoa to radicals is discussed in relation to the diverse enzymatic activities, vitamin E content, and peroxidative response. These factors are correlated with the different stages of sperm cell maturation, which are characterized-from caput to cauda epididymidis-by progressive destabilization of the plasma and acrosomal membranes.

Animals↗
PubMed1998

Cerebral hypoperfusion detected by SPET in early neuro-Behçet syndrome.

We used brain single-photon emission tomography (SPET) to detect hypoperfused areas in 15 consecutive Behçet syndrome patients. Five were suspected of having neuro-Behçet syndrome, having at least one neurological symptom. For these patients, SPET was performed within 1 month of the onset of nervous system involvement. The 15 patients fulfilled the criteria of the International Study Group for Behçet syndrome. Neurological assessment and SPET were complemented by EEG in all five patients with suspected neuro-Behçet syndrome and by magnetic resonance imaging in three. Brain SPET detected hypoperfused regions in all five neurological patients; EEG showed abnormalities in three. Magnetic resonance imaging was normal in the three patients in whom it was performed. SPET was negative in all patients without neurological involvement and 20 healthy controls. SPET detected a reduction in brain blood flow in early neuro-Behçet syndrome, but there was no definitive correlation between the hypoperfused brain regions and the clinical features. Further studies are required to evaluate the significance of brain hypoperfusion and the value of SPET in the early diagnosis of neuro-Behçet syndrome.

Adult↗
PubMed1997

Distribution and possible novel role of phospholipid hydroperoxide glutathione peroxidase in rat epididymal spermatozoa.

The selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPx, EC 1.11.1.12) is present, in both free and membrane-bound form, in several mammalian tissues. It utilizes thiols such as glutathione to specifically scavenge phospholipid hydroperoxides. The testis exhibits the highest PHGPx-specific activity so far measured, and interest in the presence and function of the enzyme in this tissue has recently grown. Here we report the localization of PHGPx in rat epididymal spermatozoa and its distribution in subfractions obtained by sucrose density gradient centrifugation. Immunochemical evidence and enzymatic activity revealed for the first time that PHGPx is present in sperm heads and tail midpiece mitochondria. The binding of the enzyme to spermatozoa, head, and mitochondria was barely affected by ionic strength or thiols or detergents, as compared to the detachment of PHGPx obtained from testis nuclei. Moreover, we demonstrated that pure PHGPx exhibits a higher thiol-oxidase activity toward isolated epididymal caput protamines than toward protamines from epididymal cauda. These results suggest a role for the enzyme in the maturation of spermatozoa through the metabolism of hydroperoxides and sperm thiol oxidation, in addition to its serving as an antioxidant protector.

Animals↗
PubMed1996

Rat testis mitochondrial phospholipid hydroperoxide glutathione peroxidase does not protect endogenous vitamin E against Fe2+-induced (lipo)peroxidation.

Rat testis mitochondria contain large amounts of both seleno-enzyme phospholipid hydroperoxide glutathione peroxidase (EC 1.11.1.12, PHGPx) and alpha-tocopherol. The scavenger role of vitamin E consists of transforming the lipoperoxyl radicals into lipid hydroperoxides, thus interrupting the peroxidative cascade. These hydroperoxides are in turn substrates of the PHGPx, which is considered one of the most important specific enzymes capable of protecting, in situ, the membranes from lipid peroxidation. A connection or synergism could, therefore, be envisaged between vitamin and enzyme opposing lipid damage in the mitochondria. Here we present data concerning the HPLC evaluation of vitamin E consumption in rat testis mitochondria and mitochondrial membranes, under different conditions of PHGPx activity, after Fe2+-induced lipid peroxidation. We have found that the enzyme activity, under the conditions tested, does not spare vitamin E from its peroxidation, therefore indicating that the postulated synergism between PHGPx and alpha-tocopherol can be excluded in rat testis mitochondria.

Age Factors↗
PubMed1996

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) in rat testis nuclei is bound to chromatin.

In rat testis nuclei the activity of the selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPx, EC 1.11.1.12) is much higher than in other tissues and subcellular compartments, with the sole exception of mitochondria. In nuclei, the bound enzyme is solubilized by DNase I treatment, thus suggesting a binding to chromatin. Treatment with ionic strength releases about 70% of bound PHGPx, suggesting that electrostatic bonds are involved. Immunogold electron microscopy indicates the association of PHGPx with chromatin structures in isolated nuclei. A possible interpretation of these data is a PHGPx protective role against DNA peroxidative damage. Furthermore, in agreement with kinetic and structural information, PHGPx-chromatin binding could suggest an hypothetical thiol oxidase activity toward specific thiol bearing proteins which could substitute for GSH as alternative donor substrates. Such activity could give to the enzyme a new important function which is not only protective but also has a specific regulatory function in chromatin condensation.

Animals↗
PubMed1994

Distribution of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in rat testis mitochondria.

The distribution of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in isolated rat testis mitochondria was investigated, using a reverse sucrose density gradient centrifugation procedure for the separation of the inner and outer membranes and the contact sites between the two membranes. The results indicate that PHGPx is largely localized in the contact sites fraction. This finding might therefore suggest that the enzyme has more than just an antioxidant function.

Animals↗
PubMed1994

Characterization of a voltage-dependent anionic channel in fused synaptosomes isolated from rat hippocampi.

The inside out configuration of the patch-clamp technique was used to study single-channel anionic currents from purified hippocampal synaptosomes fused into liposomes to form giant proteoliposomes. At least six different anionic channels with unitary conductances of 22-150 pS were found. The most frequently observed was the 32-pS conductance channel. This was voltage-dependent; the open probability increased from 0.20 at -40 mV to 0.46 at 40 mV. This channel may be involved in the repolarization of nerve terminal membranes after an action potential, thus, limiting the duration of the spike and the transmitter release.

Animals↗
PubMed1992

Ionic permeability of the mitochondrial outer membrane.

The ionic permeability of the outer mitochondrial membrane (OMM) was studied with the patch clamp technique. Electrical recording of intact mitochondria (hence of the outer membrane (OM], derived from mouse liver, showed the presence of currents corresponding to low conductances (less than 50 pS), as well as of four distinct conductances of 99 pS, 152 pS, 220 pS and 307 pS (in 150 mM KCl). The latter were voltage gated, being open preferentially at positive (pipette) potentials. Very similar currents were found by patch clamping liposomes containing the isolated OM derived from rat brain mitochondria. Here a conductance of approximately 530 pS, resembling in its electrical characteristics a conductance already attributed to mitochondrial contact sites (Moran et al. 1990), was also detected. Immunoblot assays of mitochondria and of the isolated OM with antibodies against the outer membrane voltage-dependent anion channel (VDAC) (Colombini 1979), showed the presence of the anion channel in each case. However, the typical electrical behaviour displayed by such a channel in planar bilayers could not be detected under our experimental conditions. From this study, the permeability of the OMM appears different from what has been reported hitherto, yet is more in line with that multifarious and dynamic structure which apparently should belong to it, at least within the framework of mitochondrial biogenesis (Pfanner and Neupert 1990).

Animals↗
PubMed1991

Distribution of glutathione peroxidases and glutathione reductase in rat brain mitochondria.

The distribution of glutathione reductase (GR), glutathione peroxidase (GPx) and phospholipid hydroperoxide glutathione peroxidase (PHGPx) in isolated rat brain mitochondria was investigated, using a fractionation procedure for the separation of inner and outer membranes, contact sites between the two membranes and a soluble fraction mainly originating from the mitochondrial matrix. The data indicate that GR and GPx are concentrated in the soluble fraction, with a minor portion of the two enzymes being associated with the contact sites. PHGPx is localized largely in the inner membrane. The possible functional significance of these findings is discussed.

Animals↗
PubMed1990

Hydrogen peroxide production by monoamine oxidase in isolated rat-brain mitochondria: its effect on glutathione levels and Ca2+ efflux.

H2O2 production and accumulation during incubation of isolated rat-brain mitochondria with substrates of monoamine oxidase A and B were investigated. All substrates gave rise to an accumulation of H2O2 which was inhibited by malate + pyruvate or isocitrate, consistent with a need for mitochondrial NADPH to maintain glutathione in the reduced state. However, in the absence of these additions the level of reduced glutathione decreased only by about 30%, indicating that only a fraction of the mitochondrial glutathione pool was accessible to the glutathione peroxidase and glutathione reductase activities responsible for the continuous removal of H2O2 generated by monoamine oxidase. The H2O2 accumulation was also inhibited by externally added reduced glutathione or NADPH but not NADH. External NADPH was oxidized by added oxidized glutathione but not alpha-ketoglutarate + NH4+. These results suggest that the removal of H2O2 generated by monoamine oxidase proceeds by way of special fractions of glutathione peroxidase and glutathione reductase that are located in the intermembrane space of mitochondria in such a way that they can react with both intra- and extra-mitochondrial glutathione and NADPH, possibly at the contact sites between the inner and outer mitochondrial membranes. Evidence is also presented that H2O2 generated by monoamine oxidase enhances Ca2+ release from mitochondria and may thus function as a regulator of mitochondrial Ca2+ efflux.

Animals↗
PubMed1990

Electrophysiological characterization of contact sites in brain mitochondria.

From morphological and biochemical studies it has been recognized that the regions where the outer and inner membranes of mitochondria come in close contact (contact sites) can be the route mechanism through which mitochondria interact directly with the cytoplasm. We have studied these regions electrophysiologically with the patch clamp technique, with the aim of understanding if this direct interaction is mediated by high conductance ion channels similar to the channel already detected in the inner membrane of mitochondria (Sorgato M. C., Keller, B. U., and Stühmer, W. (1987) Nature 330, 498-500). Contact sites isolated from rat brain mitochondria were thus incorporated into liposomes subsequently enlarged sufficiently to be patch clamped. This study shows that these particular fractions contain ion channels with conductances ranging from approximately 5 picosiemens to 1 nanosiemens (in symmetrical 150 mM KCl). Most of these channels are not voltage-dependent and can be open at physiological potentials sustained by respiring mitochondria. The lack of voltage sensitivity seems not to be the outcome of methodological artifacts, as voltage-gated channels are detected in giant liposomes containing either the outer mitochondrial membrane or a partially purified fraction of the inner mitochondrial membrane. These data therefore indicate that channels present in mitochondrial contact sites have properties which render them amenable to perform several of the functions hypothesized for these regions, particularly that of translocating macromolecules from the cytoplasm to the matrix of mitochondria.

Animals↗
PubMed1988

Mitochondrial boundary membrane contact sites in brain: points of hexokinase and creatine kinase location, and control of Ca2+ transport.

The location of hexokinase at the surface of brain mitochondria was investigated by electron microscopy using immuno-gold labelling techniques. The enzyme was located where the two mitochondrial limiting membranes were opposed and contact sites were possible. Disruption of the outer membrane by digitonin did not remove bound hexokinase and creatine kinase from brain mitochondria, although the activity of outer membrane markers and adenylate kinase decreased, suggesting a preferential location of both enzymes in the contact sites. In agreement with that, a membrane fraction was isolated from osmotically lysed rat brain mitochondria in which hexokinase and creatine kinase were concentrated. The density of this kinase-rich fraction was specifically increased by immuno-gold labelling of hexokinase, allowing a further purification by density gradient centrifugation. The fraction was composed of inner and outer limiting membrane components as shown by the specific marker enzymes, succinate dehydrogenase and NADH-cytochrome-c-oxidase (rotenone insensitive). As reported earlier for the enriched contact site fraction of liver mitochondria the fraction from brain mitochondria contained a high activity of glutathione transferase and a low cholesterol concentration. Moreover, the contacts showed a higher Ca2+ binding capacity in comparison to outer and inner membrane fractions. This finding may have regulatory implications because glucose phosphorylation via hexokinase activated the active Ca2+ uptake system and inhibited the passive efflux, resulting in an increase of intramitochondrial Ca2+.

Animals↗