181 research outputs found
Modificazioni delle proprietà della membrana plasmatica e differenziazione cellulare nelle cellule HT 29, linea cellulare di adenocarcinoma umano del colon
No full textIl colesterolo ed i fosfolipidi sono sostanze implicate nella modulazione della fluidità della membrana plasmatica della cellula. La fluidità è determinata anche dal grado di insaturazione delle catene aciliche dei fosfolipidi. La membrana plasmatica di molte cellule tumorali possiede una fluidità maggiore di quella delle rispettive cellule normali. Recenti studi epidemiologici hanno messo inoltre in evidenza una relazione inversa tra concentrazione sierica del colesterolo e l'incidenza di mortalità per cancro. Probabilmente l'ipocolesterolemia influenza la fluidità della membrana plasmatica della cellula. Alcune cellule metastatizzanti hanno una membrana più fluida di quella delle cellule normali. Pertanto lo scopo di questa ricerca, oltre a caratterizzare le proprietà della membrana delle cellule HT 29 è quello di verificare il ruolo giocato dal colesterolo sulla crescita cellulare, sulla produzione ed il rilascio di CEA e di poliamine, sulle proprietà elettrofisiologiche della cellula, sulla morfologia cellulare e sul tentativo che tale sostanza potrebbe esercitare sulla differenziazione delle HT 29. Inoltre è stato studiato il trasporto attivo, Na+ -dipendente, di uno zucchero, il 3-O-metil-D-glucosio (3MG), che utilizza lo stesso "carrier" del D-glucosio ma che non viene metabolizzato
The use of FPGA in drift chambers for data transfer rate reduction
No full textThe widespread use in drift chambers of light helium-based gas mixtures is aimed to minimize the multiple scattering contribution to the momentum measurement for low momentum particles. However, because of the limited number of ionization clusters produced, these gas mixtures introduce a substantial bias in the impact parameter estimate, particularly for short impact parameters and small drift cells. Recently, an alternative impact parameter reconstruction technique (Cluster Timing) has been proposed, which consists in using, with statistical considerations, the distribution of the drift times of all individual ionization clusters, to reduce the bias and, consequently, to improve the spatial resolution. A hardware test of such application is illustrated with the details of the applied algorithm
Modification of membrane parameters (antigen expression and electrophysiological characteristics) and cell differentiation
No full textCholesterol and phospholipids play an important role in the modulation of plasma membrane fluidity which in turn affects cell behaviour. Several transformed cells display an increased membrane fluidity; in fact, some reports have indicated that metastatizing cells possess a more fluid plasma membrane than the original tumor cells. By growing tumor cells in the presence of cholesterol, differentiation process might, in some respect, be influenced. HT 29 cells, an established cell line of human colon adenocarcinoma, were grown in RPMI 1640 medium containing cholesterol at 25, 50 and 100 μg/ml concentrations. Only in the case of the highest cholesterol concentration the number of cells at confluence was reduced; in addition, cholesterol stimulated carcinoembrionic antigen expression. Electrical membrane potential measured with microelectrodes was -19.6 ± 0.9 mV (n = 28) in controls and -23.6 ± 1.6 mV (n = 25) in the presence of cholesterol. The lowering of the external K+ concentration below that present in the medium resulted in a hyperpolarization that was higher in the presence than in absence of cholesterol. On the contrary, the increase of the external K+ concentration led to a depolarization greater in controls than in the presence of cholesterol. It would, therefore, seem that cholesterol increases the electrical resistance of the plasma membrane of HT 29 cells. Finally, cholesterol-treated cells showed at the electron microscope the disappearance of intracytoplasmic lumina and the tendency of microvilli to settle at one pole of the cell; both phenomena seem to indicate an attempt of the cell to differentiate
Modification of membrane parameters and cell differentiation
No full textHT-29 cells are an established cell line of human colon adenocarcinoma. Considering that several transformed cells possess an increased membrane fluidity and cholesterol (Ch) and phospholipids play an important role in the modulations of plasma membrane fluidity we determined some parameters in normal and Ch containing media. The presence of 100 mg/ml Ch causes an initial cell loss and reduces growth rate until confluence. CEA production is much higher in Ch treated cells than in controls during the first four days of colture. The cellular [Na+], and [K+] are in the range of normal enterocytes. In low Na+ experiments there is a great reduction of Vmax, Km is not modified. The unidirectional flux of sugar is linear within 2 seconds. Time-course experiments show a decrease of equilibrium uptake in low Na+ and in ouabain versus controls. Electron microscopy shows that cells grown in Ch tend to collect the microvilli at one pole. Shifting back to a normal medium, the microvilli lose their polar distribution. The membrane potential is higher in Ch grown cells (-23.6 ± 1.6 mV vs. -19.6 ± 0.9 mV). The lowering of [K+]o results in a hyperpolarization, higher in the presence than in the absence of Ch. The increase of [K+]o leads to a depolarization greater in controls than in the presence of Ch. Ch seems to increase the electrical resistance of the membrane. Amiloride hyperpolarizes the cell only after a long exposure. 10-3 M ouabain depolarizes the cell at lower concentrations, ouabain depolarizes more rapidly the cells grown in normal conditions than those grown in Ch. In conclusion the Ch affect plasma membrane properties and the results seem to indicate an attempt by the cell to differentiate
The use of FPGA in drift chambers for data transfer rate reduction
No full textThe widespread use in drift chambers of light helium-based gas mixtures is aimed to minimize the multiple scattering contribution to the momentum measurement for low momentum particles. However, because of the limited number of ionization clusters produced, these gas mixtures introduce a substantial bias in the impact parameter estimate, particularly for short impact parameters and small drift cells. Recently, an alternative impact parameter reconstruction technique (Cluster Timing) has been proposed, which consists in using, with statistical considerations, the distribution of the drift times of all individual ionization clusters, to reduce the bias and, consequently, to improve the spatial resolution. A hardware test of such application is illustrated with the details of the applied algorithm
Safety and efficacy of spray intranasal live attenuated influenza vaccine : systematic review and meta‐analysis
Get PDFAlthough influenza is a major public health concern, little is known about the use of spray live attenuated influenza vaccine (LAIV) among adults. For this reason, we conducted a systematic review and meta‐analysis to investigate the efficacy and safety of LAIV, especially in adults with/without clinical conditions and children <2 years, with the final aim of possibly extending the clinical indications. PubMed/MEDLINE and Scopus were the two databases consulted through February 2021. The Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines were followed. A critical appraisal was conducted. Analyses were performed by using ProMeta3 software. Twenty‐two studies were included, showing that LAIV was associated with a higher probability of seroconversion when compared with a placebo and considering the A/H1N1 serotype (pooled OR = 2.26 (95% CI = 1.12–4.54), p‐value = 0.022; based on 488 participants, without heterogeneity (I2 = 0.0%)). The meta‐analysis also confirmed no significant association with systemic adverse events. Only rhinorrhea, nasal congestion, and sore throat were significantly associated with LAIV compared to the placebo. Despite limited available evidence, LAIV has proved to be a safe and effective flu vaccination, also due to its very low invasiveness, and our review’s results can be considered a starting point for guiding future research and shaping forthcoming vaccination campaigns
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