Carbodiimide inactivation of MMPs and effect on dentin bonding.

The use of protein cross-linking agents during bonding procedures has been recently proposed to improve bond durability. This study aimed to use zymography and in situ zymography techniques to evaluate the ability of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linker to inhibit matrix metalloproteinase (MMP) activity. The hypotheses tested were that: (1) bonding procedures increase dentin gelatinolytic activity and (2) EDC pre-treatment prevents this enzymatic activity. The zymographic assay was performed on protein extracts obtained from dentin powder treated with Optibond FL or Scotchbond 1XT with or without 0.3M EDC pre-treatment. For in situ zymography, adhesive/dentin interfaces were created with the same adhesives applied to acid-etched dentin slabs pre-treated or not with EDC conditioner. Zymograms revealed increased expression of dentin endogenous MMP-2 and -9 after adhesive application, while the use of EDC as a primer inactivated dentin gelatinases. Results of in situ zymograpy showed that hybrid layers of tested adhesives exhibited intense collagenolytic activity, while almost no fluorescence signal was detected when specimens were pre-treated with EDC. The correlative analysis used in this study demonstrated that EDC could contribute to inactivate endogenous dentin MMPs within the hybrid layer created by etch-and-rinse adhesives.

Surface and inner cell behaviour along skeletal muscle cell in vitro differentiation.

During muscle tissue differentiation, in particular in the formation of myotubes from the myoblasts, plasma membrane changes its morpho-functional characteristics. In this study, muscle cell membrane behaviour has been studied along the differentiation of C2C12, a mouse myoblastic adherent cell line. Flat undifferentiated cells, cultured for 3-4 days in the differentiation medium, progressively become thick, long and multinucleated myotubes covered with microvilli. They lose stress fibers and adhesion to the underlying substrate evidentiating an actin redistribution, followed by the spatial organization of thick and thin myofilaments. Sarcomeres and myofibrils occasionally appear, even if a certain percentage of "myosacs" containing randomly oriented filaments can be identified all along the differentiation. M-cadherin, a molecule involved in cell-cell adhesion, also appears in the early differentiation stage, during myoblast fusion. Occasional focal contractions can also be observed in myotubes, which prompt an electrophysiological membrane analysis. When studied by means of patch clamp technique, resting membrane potential appears to undergo a transient depolarization, while input resistance increases until day 5 after differentiation induction, then successively decreases. Capacitance declines until day 5, later appearing enhanced. Moreover, with the induction of differentiation, the pattern of functional voltage-dependent ion channels changes. Therefore, during myogenesis, cell maturation is coupled with changes in cell membrane morphological features and functional characteristics.

C2C12 murine myoblasts as a model of skeletal muscle development: morpho-functional characterization.

In this study, the differentiation of C2C12 cells, a primary line of murine myoblasts, was investigated by a multiple technical approach. Undifferentiated cells, and those at intermediate and final differentiation times, were studied at the reverted microscope, by conventional and confocal immunofluorescence, and by transmission and scanning electron microscopy. The general monolayer architecture changed during differentiation from fusiform or star-shaped cells to elongated confluent cells, finally originating long, multinucleated myotubes. Sarcomeric actin and myosin are present also in undifferentiated myoblasts, but progressively acquire a structured pattern up to the appearance of sarcomeres and myofibrils at about 5 days after differentiation induction. Myotubes show a particular positivity for actin and myosin, and M-cadherin, an adhesion molecule characteristic, as known, of satellite cells, also seems to be involved in their assembling. Rare apoptotic patterns, as evidenced by the TUNEL technique, appear during myoblast maturation.

[Survey of physical activity and doping in a sample of 6,915 students aged 14-18 years]. / Rilevazione dell'attività motoria e dell'uso di integratori e sostanze dopanti in un campione di 6915 studenti di età compresa fra i 14 e i 18 anni.

AIM: Promoting physical activity is one of the main goals of health-promotion policies. The period of adolescence is characterised by a high rate of abandonment of any physical activity. In this age range, moreover, the risk of assuming substances in order to improve muscular-mass or athletic results is concrete. This study quantifies the involvement in physical activities and substance assumption in a sample of 6915 students aged 14 to 18 years and living in 7 different areas, mostly in northern Italy. METHODS: The survey's tool is an adapted and modified vision of the Youth Risk Behaviour Surveillance questionnaire, created by US Centers for Disease Control and Prevention (CDC). RESULTS: The study showed a high percentage of the sample not involved in any form of physical activity out of school (33.8%), more among girls (44.1%) than boys (21.2%). Between 14 and 18 years, a continuous reduction of involvement in physical activity is evident, while the percentage of totally physically inactive subjects rises from 30.1% to 43%. Finally, 5.6% in our sample admitted to have been using substances to improve muscular-mass or athletic results at least once in the past. CONCLUSION: According to this study, only a minority of the interviewed adolescents is involved in a regular physical activity. In males, using substances to improve physical strength showed to be rather diffused. Specific health promotion projects are suggested.

[Assessment of eating disorders-related risk in a cohort of adolescents living in Northern Italy. Results from a multicenter study]. / Valutazione del rischio di disturbi del comportamento alimentare negli adolescenti del Nord Italia. Risultati di uno studio multicentrico.

BACKGROUND: Clinical evidence and epidemiological research show an increasing number of subjects trying to become lean and reaching consequently harmful weight conditions. Aim of this paper is to assess the risk for eating disorders during adolescence. METHODS: In a multicentric study high school students of 5 different districts of Northern Italy have been asked to fill up anonymously the Italian version of the American YRBSS (Youth Risk Behaviour Surveillance System) questionnaire. For each school a section has been selected and between January and March 1999, students of every level have been involved. The data enrollected have been analysed using EpiInfo6. RESULTS: The study involved 4135 adolescents (57% girls and 43% boys) coming from 260 classes and 47 different schools. The proportion of boys perceiving themselves as overweight and underweight was the same (22%), while the proportion of girls considering themselves overweight raised up to 42%. The majority of the girls (53%) is trying to slim making use of physical activity (48%), diets (32%), vomiting (8%) and drugs (5%). CONCLUSIONS: Our data suggest that specific projects focusing on primary and secondary prevention of eating disorders should be considered for high schools. In addition, further studies are suggested to understand characteristics and behaviours related to eating disorders.

Neuropsychological changes after carotid endarterectomy.

Carotid endarterectomy (CEA), performed to prevent stroke, could lead to changes in cognitive functions. Sixty-four patients with severe carotid stenosis undergoing CEA treatment were evaluated by means of a detailed neuropsychological assessment before (baseline), from one to two weeks (1st follow up) after and 3 months (2nd follow up) after surgical operation. A significant post-CEA improvement was found in verbal memory and attention (p<0.05), while other cognitive functions showed no significant changes.