44 research outputs found
The effect of selective low-density lipoprotein apheresis on plasma lipoperoxides and antioxidant vitamins in familial hypercholesterolemic patients
No full textFamilial hypercholesterolemia (FH) is an autosomal dominant genetic disorder characterized by a lifelong elevation in the concentration of low-density lipoprotein (LDL) bound cholesterol in blood by cholesterol deposits and by early coronary artery disease. The LDL apheresis technique has been introduced with the goal of reducing LDL cholesterol levels, thereby preventing the development of atherosclerosis. The literature on LDL apheresis reports 2 different facets, the therapeutic aspect associated with the lessening of LDL concentration and the initiation of a peroxidation process associated with the biocompatibility of the artificial membrane. Lipid and protein peroxidation gives rise to toxic and atherogenic hydroperoxide, mostly lipid hydroperoxides, and derivative compounds, which may offset the benefit of the procedure. In this paper, plasma hydroperoxide levels are determined along with the elevation of the serum and LDL antioxidant status in hypercholesterolemic patients before and following repeated LDL apheresis sessions. Hydroperoxide concentration has been expressed both in terms of plasma volume and LDL concentration. A highly significant increase in LDL lipid hydroperoxides is demonstrated when expressed in terms of LDL concentration and is associated with the LDL apheresis procedure. The usefulness of antioxidant supplementation in LDL apheresis is discussed
Photoinduction of micronuclei by 4,4',6 trimethylangelicin and 8-methoxypsoralen in different experimental models
No full textThe frequencies of micronuclei induced by treatment with 4,4',6-trimethylangelicin (TMA) and 8-methoxypsoralen (8-MOP) have been compared in the following experimental models: (1) peripheral normochromatic erythrocytes (NCE) during 10 days after single p.o. administration of TMA or 8-MOP in male and female mice; (2) peripheral NCE during photocarcinogenesis by TMA or 8-MOP topically administered to female mice; (3) primary cultures of human skin fibroblasts treated with TMA or 8-MOP. The frequency of micronuclei in peripheral NCE of mice (both sexes) was significantly enhanced after p.o. administration of TMA or 8-MOP. This latter was more active than TMA in inducing chromosomal damage. No increased frequencies of micronuclei in peripheral NCE were detected in mice subjected to TMA or 8-MOP photocarcinogenic treatment, even when malignancies developed. In human fibroblast cultures, at equimolar concentrations, the induction of lethal effects by TMA in the presence of 365-nm radiation was higher than that exerted by 8-MOP. At equal survival, however, TMA showed practically the same activity as 8-MOP in the induction of micronuclei. Our findings provide evidence of genotoxicity by TMA administered p.o. without irradiation and give further information about photogenotoxicity of these substances
AKT come bersaglio molecolare dell'attività di fenretinide nel glioblastoma umano
No full textIl glioblastoma multiforme rappresenta la forma più maligna dei tumori cerebrali. La prognosi è fatale con un tempo medio di sopravvivenza non superiore ai 12 mesi. Studi recenti hanno identificato nell'attivazione della chinasi Akt/PKB un ruolo importante nella tumorigenesi, crescita ed aumento del grado di malignità in questo tumore. La chinasi Akt/PKB inibisce il processo apoptotico attraverso l'inattivazione di BAD e dei fattori di trascrizione forkhead; inoltre, essa è coinvolta nella progressione del ciclo cellulare tramite regolazione diretta della Ciclina D1. Akt/PKB può quindi rappresentare un nuovo importante bersaglio nella strategia terapeutica del glioblastoma umano. La Fenretinide o N-(4-idrossifenil) retinamide è un derivato sintetico dell' acido retinoico, possiede bassa epatotossicità ed ha una buona tollerabilità in vivo. Interessante la sua composizione altamente lipofila che le permette di attraversare la barriera emato-encefalica. Numerosi studi hanno dimostrato la capacità di questo farmaco di indurre apoptosi in vitro e di poter esercitare effetti chemiopreventivi e terapeutici. Il meccanismo molecolare d'azione non è stato ancora del tutto chiarito. Fenretinide ha dimostrato di poter agire con meccanismi dipendenti e indipendenti dai recettori per i retinoidi e di indurre apoptosi tramite attivazione della cascata delle caspasi via ceramide e specie reattive dell'ossigeno. In leucemie, linfoblastomi, neuroblastomi e carcinomi mammari in vitro l'attività antiproliferativa del farmaco è associata ad una riduzione dell'espressione di Ciclina D1 e Cdk4. Entrambe queste molecole sono coinvolte nella tumorigenesi del glioblastoma e rappresentano bersagli molecolari del sistema Akt/PKB.
Dati di letteratura indicano che Fenretinide inibisce la proliferazione in glioblastomi umani in vitro, con induzione di apoptosi mediata dalla caspasi 3.
Qui sono riportati i risultati di uno studio teso alla individuazione dell’eventuale ruolo di AKT nel meccanismo molecolare dell’azione esercitata da Fenretinide nel glioblastoma umano. L'analisi è stata condotta in vitro in due linee cellulari di glioblastoma umano (CRS-A2 e A-172), esprimenti ciascuna alti livelli di Akt/PKB. E' stata valutata l'attività antiproliferativa di Fenretinide, non nota prima in queste linee tumorali, e confermata l'induzione di apoptosi, tramite attivazione della caspasi 3. In parallelo, mediante Western blotting, è stata condotta una analisi di espressione delle principali proteine coinvolte nel pathway di Akt/PKB. I risultati dimostrano inibizione della crescita indotta da Fenretinide, in entrambe le linee cellulari; il processo apoptotico viene attivato dal farmaco nella linea CRS-A2, con un meccanismo caspasi-3 dipendente. In parallelo all'inibizione della proliferazione cellulare si osservano una down-regolazione del complesso Ciclina D1/Cdk4, della p21CIP1 e di Akt/PKB: in questo caso, con una riduzione sia dei livelli basali di Akt, che della sua forma fosforilata.
La chinasi Akt/PKB, di cui è noto il ruolo nel sostenere il fenotipo tumorale, quando costitutivamente attivata, si dimostra quindi bersaglio molecolare innovativo dell’azione di Fenretinide nel glioblastoma umano, aprendo la strada a nuove prospettive terapeutiche
DANNO AL DNA IN CELLULE DELL’IPPOCAMPO DI GERBILLO DOPO TRATTAMENTO DI ISCHEMIA/RIPERFUSIONE
No full textLa riperfusione post-ischemica rappresenta una significativa causa di morbilità e di morte in diversi campi della medicina che comprendono, tra gli altri, l'infarto del miocardio, l'ischemia cerebrale, lo shock settico o emorragico e il trapianto d'organo. A livello del microcircolo il danno da ischemia/riperfusione (I/R) è provocato, oltre che dall'accumulo chemiotattico e dall'adesione all'endotelio di leucociti circolanti, dalla generazione di specie reattive dell'ossigeno e dell'azoto quali l'anione superossido e il perossinitrito. Il danno al DNA da parte di queste specie reattive è stato dimostrato sia in modelli sperimentali in vitro che in cellule in cultura. Una procedura sperimentale efficace per mettere in evidenza il danno al DNA sotto forma di rotture a singola elica (SSB) in cellule in cultura è la micro-gel-elettroforesi su singola cellula (Comet test). Una modifica di questa tecnica (Halo-Diffusion Assay - HDA) consente di evidenziare anche la frammentazione cromatinica, strettamente correlata all’apoptosi. Recentemente, l’esecuzione di questi saggi si è resa possibile usando come campione anche frammenti tissutali provenienti da animali da esperimento
Effects of beta-carotene and alpha-tocopherol on photogenotoxicity induced by 8-methoxypsoralen: the role of oxygen
No full textThe protective effect of beta-carotene (beta-C) and alpha-tocopherol (alpha-T), singularly and in equimolar mixtures, toward the photomutagenicity induced by 8-methoxypsoralen (8-MOP), at different oxygen partial pressure (pO2), was evaluated in two different experimental models: Salmonella typhimurium TA102 and Saccharomyces cerevisiae D7. After phototreatment with 8-MOP, the results show a lethal effect under hypoxic conditions in both experimental model systems, an increase in revertants associated to the pO2 increase in S. typhimurium TA102, and a decrease in revertants and convertants associated to the pO2 increase in S. cerevisiae D7. In S. typhimurium TA102, in atmospheric condition, beta-C and alpha-T (1.86 or 18.6 microM) show a protective effect only at the higher dosage. Alpha-T was more protective than beta-C. The equimolar mixtures show an antimutagenic effect at both dosage used with a synergistic effect at lower dosage and an additive antimutagenic activity at higher dosage. An inhibition of the spontaneous mutagenicity by mixtures at higher dosage was also observed. The results obtained in S. typhimurium TA102 show an antimutagenic effects of beta-C, alpha-T and their mixture at 190 mmHg pO2, confirming the data obtained in air condition. At 380 mmHg pO2, alpha-T and the mixture show a significant antimutagenic activity; at 570 mmHg pO2, only alpha-T is protective. At 760 mmHg pO2, no protective effect was observed by the two antioxidants, and beta-C increases the photomutagenicity induced by 8-MOP. In S. cerevisiae D7 a protective effect was only observed at 380 mmHg pO2 with the mixture. No antigenotoxic effect was found in the other experimental conditions, even if the uptake of the two antioxidants was confirmed by HPLC. Our results underline the role of oxygen in the photomutagenicity induced by 8-MOP and in the antimutagenic activity of beta-C and alpha-T. This is the first report confirming in a cellular experimental model the data obtained in some chemical systems: the protective effect of beta-C only at low pO2 and the synergistic effect of mixture of beta-C and alpha-T
EXPERIENCES IN CAI-BASED TEACHING OF BIOMEDICAL SCIENCES - THE NEED FOR AN ALL-PURPOSE SHELL
No full textAnthocyanidins decrease endothelin-1 production and increase endothelial nitric oxide synthase in human endothelial cells
No full textEpidemiological and intervention studies correlate anthocyanin-rich beverages and a low incidence of coronary heart diseases, Since endothelin-1 (ET-1) and nitric oxide (NO) produced by endothelial NO synthase (eNOS) are vascular tension regulators secreted by endothelial cells, we studied the influence of two anthocyanidins, namely cyanidin (CY) and delphinidin (DP), on the regulation of ET-I and eNOS in cultured human umbilical vein endothelial cells (HUVECs). Aglycon anthocyanidin forms, such as CY and DP, may be present in vivo after the first deglycosylation step occurring in the jejunum and in the liver. DP showed a major action compared to CY inducing a significant dose-dependent inhibitory effect on both protein and mRNA levels of ET-1. CY and DP both increased the protein level of eNOS, but DP showed the major effect raising eNOS protein in a dose-dependent manner. To correlate the vasoprotective effect of CY and DP with their antioxidant activity, we analysed also the antioxidant effect of anthocyanidins both in vitro and in HUVECs. In particular, we examined the effect of anthocyanidins on endothelial heme oxygenase-1 (HO-1), an inducible stress protein. In all tests, DP showed a higher antioxidant activity than CY. Finally, the antiproliferative effect induced by DP was detected in HUVECs. DP and CY differ in the number and position of hydroxyl groups in their structure;, therefore, the greater biological activity by DP, compared with CY, seems to be due to the presence of the three hydroxyl groups on the B ring in the molecular structure of DP
Resveratrol, but not its derivatives, interfere with cell cycle progression by inhibiting DNA replication in normal and tumor cell lines.
No full textThe resveratrol-analogue 4,4’-dihydroxy-trans-stilbene suppresses transformation in normal mouse fibroblast and inhibits proliferation and invasion of human breast cancer cells
No full text4,4′-dihydroxy-trans-stilbene (DHS) is a synthetic analog of resveratrol, a phytoalexin known for its biological activities. We previously demonstrated that DHS exerts an antiproliferative effect on normal human fibroblasts that is higher than that of the natural parent molecule. No evidence regarding its role in human cancer cell lines has been found thus far. In this study, we investigated the effects of DHS both on chemical-induced transformation of BALB/c 3T3 mouse fibroblasts and on the proliferation and invasion of human breast cancer MCF-7 cells. The results showed that DHS markedly suppresses the two-stage (3-methylcholanthrene plus 12-O-tetradecanoylphorbol-13-acetate) cell transformation. Compared with resveratrol, DHS inhibited both anchorage-dependent and -independent MCF-7 growth more efficiently. In addition, a reduction in the number of cells in S-phase, characterized by a concomitant increase in the levels of p21 and p53 proteins, together with a strong inhibition of pRb protein phosphorylation, was observed in DHS-treated cells. Furthermore, DHS effected a strong reduction in matrix metalloproteinase-2 and -9 activities, concomitantly with a marked inhibition of cell adhesion to the extracellular matrix components as well as inhibition of cell migration and invasion. Importantly, modulation of the adhesion molecule E-cadherin was also found in DHS-treated cells. Taken together, these results demonstrate that the two 4,4′-hydroxyl groups on the stilbenic backbone make DHS a more active molecule than resveratrol in inhibiting neoplastic transformation, cancer cell proliferation and invasion. In conclusion, this study suggests that DHS could be a promising anticancer agent
Enlarged Field of View in Spatially Modulated Selective Volume Illumination Microscopy
No full textThree-dimensional fluorescence microscopy is a key technology for inspecting biological samples, ranging from single cells to entire organisms. We recently proposed a novel approach called spatially modulated Selective Volume Illumination Microscopy (smSVIM) to suppress illumination artifacts and to reduce the required number of measurements using an LED source. Here, we discuss a new strategy based on smSVIM for imaging large transparent specimens or voluminous chemically cleared tissues. The strategy permits steady mounting of the sample, achieving uniform resolution over a large field of view thanks to the synchronized motion of the illumination lens and the camera rolling shutter. Aided by a tailored deconvolution method for image reconstruction, we demonstrate significant improvement of the resolution at different magnification using samples of varying sizes and spatial features
