1,720,984 research outputs found
Further studies on the antioxidant role of pyrophosphate in model membranes
No full textOur previous studies (G. Cervato et al., Chem. Phys. Lipids 56 (1990), 91-99) demonstrated that 100 muM pyrophosphate (PPi) inhibits Fe2+/ascorbate-induced peroxidation of arachidonic acid (AA) inserted in unilamellar liposomes (SUVs) of dipalmitoylphosphatidylcholine (DPPC), by chelating ferrous ions in the aqueous phase. In this work we demonstrate that the kinetics of AA peroxidation in DPPC SUVs are strongly affected by PPi, also at very low concentration (1 muM). In fact at low PPi concentration there is a longer lag-phase, while the maximum of thiobarbituric acid reactive substances (TBARS) is similar in both the presence and absence of 1 muM PPi. The lag-phase of peroxidation of AA in lysophosphatidylcholine (palmitoyl) (LysoPC) micelles is also prolonged. The AA peroxidation in membrane models without choline as the polar headgroup (dipalmitoylphosphatidylethanolamine (DPPE) SUVs, or Triton X-100 micelles), or in which AA is not free but esterified with glycerol (stearoylarachidonylphosphatidylcholine (SAPC)), is unaffected by the presence of 1 muM PPi
Variability in alpha-tocopherol antioxidant activity in the core and surface layers of low- and high-density lipoproteins
No full textThe effect of alpha-tocopherol enrichment of low- and high-density lipoproteins on Cu(2+)-catalyzed lipid peroxidation in the hydrophobic core and in the hydrophilic envelope of lipoproteins was investigated by using two pyrene derivatives, namely, cholesteryl pyrenyl hexanoate (P6Chol) and pyrene dodecanoyl sulfatide (P12CS). The progressive decrease in fluorescence of P6Chol was used to monitor lipid peroxidation in the core of LDL and HDL, whereas that of P12CS was used to follow lipid peroxidation in the envelope of both lipoproteins. alpha-Tocopherol enrichment of LDL and HDL was obtained by incubating blood plasma at 37 degrees C with different concentrations of the vitamin (25-500 microM) before lipoprotein separation. The incorporation of alpha-tocopherol in LDL and HDL presents a progressive, time-dependent increase up to 200 microM alpha-tocopherol, then a plateau up to 500 microM. In the envelopes, the added tocopherol causes a great decrease in the rate of peroxidation and a dramatic increase in the latency phase in both lipoproteins. In the cores the lengthening of latency phase resulting from alpha-tocopherol enrichment was by far greater in LDL than in HDL, and the decrease in the rate of peroxidation in both lipoproteins was less than in the envelopes
Studies on the antioxidant activity of milk caseins
No full textThe antioxidant properties of milk casein subunits (alpha-casein, beta-casein and kappa-casein) were evaluated in liposomal models. All the subunits of casein are able to inhibit Fe-induced peroxidation of arachidonic acid inserted into multilamellar liposomes of dipalmitoylphosphatidylcholine (0.2 mM and 0.8 mM, respectively). The peroxidation was monitored as thiobarbituric acid reactive substances, and the strongest inhibitory effect occurred when 500 micrograms of alpha-casein were added to 0.5 ml of liposomal suspension. At this concentration, peroxidation was completely inhibited in our experimental conditions (incubation for 2 h at room temperature, with a mixture of ferrous sulfate and ascorbate, 50 and 500 microM final concentration, respectively). The mechanisms of antioxidant action are complex, but the strongest effect is achieved by modifying the Fe2+/Fe3+ equilibrium; in fact, caseins seem to favour the autoxidation of iron, and thus inhibit lipid peroxidation
THERMODYNAMIC STATISTICAL EVALUATION OF S AND F FROM ELECTRON-SPIN-RESONANCE EXPERIMENTAL ORDER PARAMETERS
No full textA statistical analytical procedure for calculating entropy (S) and Helmholtz free energy (F) from the order parameters {Mathematical expression} obtained from ESR spectra of spin-labelled membranes is described. The method is here applied to some literature data. A brief discussion on the results is also reported
N-PYRENE DODECANOYL SULFATIDE AS MEMBRANE PROBE - A STUDY OF GLYCOLIPID DYNAMIC BEHAVIOR IN MODEL MEMBRANES
No full textAn N-linked pyrene-dodecanoyl sulfatide was employed to measure the ratio of excimer fluorescence to monomer fluoresence intensities (E/M). The E/M values provided information about both the dynamic behavior and the structural distribution of the labelled glycolipid in note dispersion of micellar sulfatides and multilamellar vesicles of different phospholipids. Most of the labelled sulfatide seems to be located in domains sequestered from the surrounding phospholipids still above the phase transition temperature of the vesicles. The glycolipids sequestered in these domain environment are less sensitive to the structural changes that the addition of cholesterol or Ca2+ can induce in the phospholipid regions during the phase transition
La riqualificazione di complessi architettonici ad alta valenza storico artistica di proprietà delle aziende USL: individuazione di strategie metodologiche per nuove ipotesi di impiego all'interno del quadro normativo nazionale
No full textLa presente memoria affronta il problema dell’applicazione ad una Azienda Sanitaria del Decreto Ministeriale del 6 febbraio 2004, emanato dalla Direzione Generale per i Beni Architettonici ed il Paesaggio di concerto con l’Agenzia del Demanio, che obbliga le pubbliche Amministrazioni a sottoporre alla verifica dell'interesse culturale i propri beni immobili. Il riconoscimento di interesse storico-artistico, secondo l’Art.12 del D. Lgs 42/2004 del “Codice dei Beni Culturali” costituisce per quelle amministrazioni che possiedono all’interno dei propri patrimoni immobiliari edifici di interesse storico, la base per la riconfigurazione del ruolo di tali beni all’interno della mission aziendale e la conseguente formulazione di proposte di riqualificazione anche per usi pubblici o privati. Tale valutazione, nel caso specifico del patrimonio di un Azienda Sanitaria, dovrà essere più attenta, in quanto una scelta strategica errata si ripercuoterebbe inevitabilmente sulle esigenze del territorio.
L’Azienda Sanitaria svolge una funzione sociale all’interno della collettività, ed è chiaro che, per perseguire il fine della tutela della salute del cittadino è incentivata ad impiegare le proprie risorse finanziarie su immobili che hanno caratteristiche di funzionalità e flessibilità adatte alle tecniche mediche moderne, mentre far sopravvivere dei beni ereditati da ex-conventi, edifici religiosi che non hanno alcuna valenza sanitaria, ma di certo complementari a questa avendo anch’essi funzione sociale, costituisce un compito di non poca difficoltà. Nell’ambito dell’amministrazione di patrimonio di un Azienda Sanitaria è necessario avere un monitoraggio dinamico di tutto il patrimonio con una programmazione che deve consentire di rendicontare costi medi e totali per ogni immobile, stabilire con buona approssimazione tutti gli interventi tecnologici finalizzati al recupero di spese gestionali, evidenziare tutte le diseconomie gestionali suggerendo quindi il rilascio e l’alienazione di tutti gli immobili improduttivi. Per questi motivi il mantenimento di un bene immobile di valenza storico-artistica diventa una criticità del processo da affrontare con le dovute attenzioni.Nel presente articolo attraverso l’analisi del patrimonio immobiliare dell’AUSL di Ferrara sono stati individuati quei beni che rientrano nella procedura di valutazione di interesse culturale tra cui la chiesa di San Carlo Borromeo di notevole pregio artistico; gli autori descrivono una possibile ipotesi di riuso dell’ex-Ospedale “Boeri” di Tresigallo (FE), edificio costruito nel 1939 su progetto del Ing. C. Frighi
Biochemical assessments of oxidative stress, erythrocyte membrane fluidity and antioxidant status in professional soccer players and sedentary controls
No full textBackground. Physical exercise is characterized by an increase in oxygen consumption by the whole body. This leads to a decrease in antioxidant levels that could promote both an increase in the markers of lipoprotein peroxidation and damage to the erythrocyte membrane with consequent modification of membrane fluidity.
Materials and methods. Different markers of oxidative stress, erythrocyte membrane fluidity and antioxidant status were determined in 20 professional soccer players and 20 sedentary controls. Plasma lipoperoxides and kinetics of Cu-stimulated plasma peroxidation were measured together with hydrosoluble ( albumin, uric acid and vitamin C), liposoluble ( vitamin E and bilirubin) and enzymatic ( superoxide dismutase and glutathione peroxidase) serum antioxidants. Erythrocyte membrane rigidity was determined by measuring fluorescence anisotropy (rs) of the fluorescent probe 1, 3, 5 diphenylexatriene.
Results. The sportsmen showed higher levels of the following plasmatic antioxidants: ascorbic acid (P < 0.0001), uric acid ( P < 0.0001), alpha-tocopherol ( P = 0.03) and superoxide dismutase activity ( P = 0.0001). According to this evidence, the lipoperoxide levels (P = 0.0158), the duration of the latency phase of plasma peroxidation ( P = 0.0123) and erythrocytes membrane fluidity ( P = 0.0152) were found to be significantly higher in the soccer players.
Discussion. Athletes undergoing regular and adequate training show improved antioxidant status together with a more fluid membrane status, which could contribute to improving both peripheral resistance to insulin and all the functional metabolic interchanges in the cellular membrane
Pyrene lipids as markers of peroxidative processes in different regions of low and high density lipoproteins
No full textThree different pyrene derivatives, pyrene decanoyl phosphatidylcholine (P10PC), pyrene dodecanoyl sulfatide (P12CS) and cholesteryl pyrenyl hexanoate (P6Chol), were used to follow lipid peroxidation in low and high density lipoproteins. Probe-labelled lipoproteins were subjected to Cu2+ catalyzed peroxidation. In all cases the fluorescence of the probes progressively decreased due to the involvement of pyrene in the peroxidative reaction. Thus, we used the fluorescence decrease of P6Chol to monitor the lipid peroxidation in the hydrophobic core of LDL and HDL, and that of the amphipatic probes, P10PC and P12CS, to follow lipid peroxidation in the envelope of both lipoproteins. The possibility of following lipid peroxidation in individual lipoprotein regions could lead to more detailed information on the oxidative modifications that play an important role in the altered cholesterol homeostasis involved in the formation of atherosclerotic lesions. No differences were observed in the peroxidation kinetics of the hydrophobic core of HDL and LDL monitored with P6Chol. On the contrary kinetics obtained with P10PC and P12 CS demonstrated the HDL envelope to be more susceptible to Cu2+ -dependent lipid peroxidation than that of the LDL. This could be due to a greater radical generating capacity of the HDL envelope and can be explained on the basis of low vitamin E levels and large amounts of polyunsaturated fatty acids esterified on phospholipids determined in HDL, and on literature evidence that indicates HDL as the principal vehicle of circulating plasma lipids peroxides.Three different pyrene derivatives, pyrene decanoyl phosphatidylcholine (P10PC), pyrene dodecanoyl sulfatide (P,,CS) and cholesteryl pyrenyl hexanoate (P6Chol), were used to follow lipid peroxidation in low and high density lipoproteins. Probe-labelled lipoproteins were subjected to Cu2+ catalyzed peroxidation. In all cases the fluorescence of the probes progressively decreased due to the involvement of pyrene in the peroxidative reaction. Thus, we used the fluorescence decrease of P6Chol to monitor the lipid peroxidation in the hydrophobic core of LDL and HDL, and that of the amphipatic probes, P10PC and P12CS, to follow lipid peroxidation in the envelope of both lipoproteins. The possibility of following lipid peroxidation in individual lipoprotein regions could lead to more detailed information on the oxidative modifications that play an important role in the altered cholesterol homeostasis involved in the formation of atherosclerotic lesions. No differences were observed in the peroxidation kinetics of the hydrophobic core of HDL and LDL monitored with P6Chol. On the contrary kinetics obtained with P10PC and P12CS demonstrated the HDL envelope to be more susceptible to Cu2+-dependent lipid peroxidation than that of the LDL. This could be due to a greater radical generating capacity of the HDL envelope and can be explained on the basis of low vitamin E levels and large amounts of polyunsaturated fatty acids esterified on phospholipids determined in HDL, and on literature evidence that indicates HDL as the principal vehicle of circulating plasma lipid peroxides
PLASMA DEPENDENT PH SENSITIVITY OF LIPOSOMES CONTAINING SULFATIDE
No full textIn this study we investigated the possibility to define relatively plasma-stable liposomal preparations in which the sensitivity to moderate drops of pH (i.e., from 7.4 to 6.8) would be induced by the presence of plasma itself. The liposome stability was monitored by determining the release of entrapped 5,6-carboxyfluorescein (CF). Using small unilamellar vesicles composed of egg phosphatidylcholine (EPC) and bovine brain sulfatide (CS) (4:1, molar ratio), the amount of CF released at pH 6.8 in the presence of 50% plasma was 3-fold that at pH 7.4, whereas no significant differences in the amount of CF released were observed when the same liposomes were incubated in buffer at pH 7.4 and 6.8, respectively. The increase in plasma induced leakage as a consequence of a drop in the pH medium, seems to specifically depend on the presence of sulfatide molecule in the bilayer since neither the acidic cholesterol 3-sulfate nor galactocerebroside, are able to induce pH sensitivity in EPC liposomes. Of all the plasma components considered (VLDL, LDL, HDL, protein fraction), VLDL seemed preferentially involved in the pH sensitivity induced by CS since they promoted an almost complete release of CF from EPC/CS small unilamellar vesicles. Thus, these liposomes are potentially a useful tool for a specific drug delivery to those pathological tissues such as tumors, inflammation sites and ischemic areas in which it is known that a lowering of the pH can occur
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