Biomedical subjects

Massimo Vassalli

Publications and source records attributed to Massimo Vassalli.

6 recordsLinked to original sources

PubMed2006

Neodymium:yttrium aluminum garnet laser irradiation with low pulse energy: a potential tool for the treatment of peri-implant disease.

Bacterial contamination may seriously compromise successful implant osteointegration in the clinical practice of dental implantology. Several methods for eliminating bacteria from the infected implants have been proposed, but none of them have been shown to be an effective tool in the treatment of peri-implantitis. In the present study, we investigated the efficacy of pulsed neodymium:yttrium aluminum garnet laser irradiation (Nd:YAG) in achieving bacterial ablation while preserving the surface properties of titanium implants. For this purpose, suspensions of Escherichia coli or Actinobacillus (Haemophilus) actinomycetemcomitans were irradiated with different laser parameters, both streaked on titanium implants, and in broth medium. It was found, by light and atomic force microscopy, that Nd:YAG laser, when used with proper working parameters, was able to bring about a consistent microbial ablation of both aerobic and anaerobic species, without damaging the titanium surface.

Aggregatibacter actinomycetemcomitans↗

PubMed2004

Laser spectral characterization in multiphoton microscopy.

Spectral and temporal characterization is a fundamental task when a tunable Ti:sapphire ultrafast laser system is operated for multiphoton microscopy applications. In the present paper simple procedures are reported that perform laser-peak-emission wavelength and bandwidth measurements without the need of any further instrumentation but a simple and inexpensive diffraction grating, by taking advantage of the confocal microscope imaging capabilities.

Equipment Design↗

PubMed2003

Simple portable lens meter.

A device measuring the optical power of simple lenses by means of moiré phenomena is described. The relevant equations are derived, and a working instrument is presented. A power measuring accuracy better than 0.25 m(-1) in the range of +/- 10 m(-1) is demonstrated.

Journal Article↗

PubMed2003

Effects of sphingosine 1-phosphate on excitation-contraction coupling in mammalian skeletal muscle.

Sphingosine 1-phosphate (S1P) activates a subset of plasma membrane receptors of the endothelial differentiation gene family (EdgRs) in many cell types. In C2C12 myoblasts, exogenous S1P elicits Ca2+ transients by activating voltage-independent plasma membrane Ca2+ channels and intracellular Ca2+-release channels. In this study, we investigated the effects of exogenous S1P on voltage-dependent L-type Ca2+ channels in skeletal muscle fibers from adult mice. To this end, intramembrane charge movements (ICM) and L-type Ca2+ current (I(Ca)) were measured in single cut fibers using the double Vaseline-gap technique. Our data showed that submicromolar concentrations of S1P (100 nM) caused a approximately 10-mV negative shift of the voltage threshold and transition voltages of q(gamma) and q(h) components of ICM, and of I(Ca) activation and inactivation. Biochemical studies showed that EdgRs are expressed in skeletal muscles. The involvement of EdgRs in the above S1P effects was tested with suramin, a specific inhibitor of Edg-3Rs. Suramin (200 microM) significantly reduced, by approximately 90%, the effects of S1P on ICM and I(Ca), suggesting that most of S1P action occurred via Edg-3Rs. Moreover, SIP at concentration above 10 microM elicited intracellular Ca2+ transients in muscle fibers loaded with the fluorescent Ca2+ dye Fluo-3, as detected by confocal laser scanning microscopy.

Animals↗

PubMed2002

Sphingosine 1-phosphate induces Ca2+ transients and cytoskeletal rearrangement in C2C12 myoblastic cells.

In many cell systems, sphingosine 1-phosphate (SPP) increases cytosolic Ca2+ concentration ([Ca2+]i) by acting as intracellular mediator and extracellular ligand. We recently demonstrated (Meacci E, Cencetti F, Formigli L, Squecco R, Donati C, Tiribilli B, Quercioli F, Zecchi-Orlandini S, Francini F, and Bruni P. Biochem J 362: 349-357, 2002) involvement of endothelial differentiation gene (Edg) receptors (Rs) specific for SPP in agonist-mediated Ca2+ response of a mouse skeletal myoblastic (C2C12) cell line. Here, we investigated the Ca2+ sources of SPP-mediated Ca2+ transients in C2C12 cells and the possible correlation of ion response to cytoskeletal rearrangement. Confocal fluorescence imaging of C2C12 cells preloaded with Ca2+ dye fluo 3 revealed that SPP elicited a transient Ca2+ increase propagating as a wave throughout the cell. This response required extracellular and intracellular Ca2+ pool mobilization. Indeed, it was significantly reduced by removal of external Ca2+, pretreatment with nifedipine (blocker of L-type plasma membrane Ca2+ channels), and inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]-mediated Ca2+ pathway inhibitors. Involvement of EdgRs was tested with suramin (specific inhibitor of Edg-3). Fluorescence associated with Ins(1,4,5)P3Rs and L-type Ca2+ channels was evident in C2C12 cells. SPP also induced C2C12 cell contraction. This event, however, was unrelated to [Ca2+]i increase, because the two phenomena were temporally shifted. We propose that SPP may promote C2C12 cell contraction through Ca2+-independent mechanisms.

Aniline Compounds↗

PubMedDate not supplied

Effect of Nd: YAG laser on titanium dental implants studied by AFM.

Bacterial contamination of dental implants is considered the main cause of implant failure. Recently, the laser treatment of the implant surface has been proposed as an useful method for decontamination. In such a view, the present study was conducted to investigate the effects of a Nd:YAG laser on the surface morphology of a titanium dental implant by means of an atomic force microscope. We demonstrated that, when the pulse energy of the laser was kept below 30 mJ, independently from the pulse rate, the laser-treated specimens exhibited a qualitatively similar surface morphology when compared to the untreated titanium implants, suggesting that the implant surface was unaffected by the treatment, in these particular conditions. We also found that, by cooling the implant surface with an air flow? during laser irradiation, the mean temperature of the implant was maintained under 37 degrees C. All these data taken together suggest the possibility to use Nd:YAG laser for the treatment of failing dental implants.

Decontamination↗