Biomedical subjects

Francesco Beltrame

Publications and source records attributed to Francesco Beltrame.

13 recordsLinked to original sources

PubMed2006

Endocytosis of GABAB receptors modulates membrane excitability in the single-celled organism Paramecium.

GABAB receptors modulate swimming behavior in Paramecium by inhibiting dihydropyridine-sensitive Ca2+ channels via G-proteins. Prolonged occupancy of GABAB receptors by baclofen results in a decrease in GABAB receptor functions. Since changes in the number of cell-surface GABAA receptors have been postulated to be of importance in modulating inhibitory synaptic transmission in neurons, we have studied the cell-surface expression and maintenance of GABAB receptors in P. primaurelia. In this study, we use immunostaining in electron and confocal microscopy to demonstrate that constitutive internalization of GABAB receptors in P. primaurelia is mediated by clathrin-dependent and -independent endocytosis. Indeed, GABAB receptors colocalize with the adaptin complex AP2, which is implicated in the selective recruitment of integral membrane proteins to clathrin-coated vesicles, and with caveolin 1, which is associated with uncoated membrane invaginations. Furthermore, when endocytosis is blocked with hypertonic medium, cytosol acidification, filipin or with a peptide that disrupts the association between amphiphysin and dynamin, the effect of baclofen on swimming is increased. These results suggest that GABAB receptor endocytosis into clathrin-coated and -uncoated vesicles represents an important mechanism in the modulation of swimming behavior in Paramecium.

Amino Acid Sequence↗

PubMed2006

Role of scaffold internal structure on in vivo bone formation in macroporous calcium phosphate bioceramics.

Purpose of this study was the analysis of the role of density and pore interconnection pathway in scaffolds to be used as bone substitutes. We have considered 2 hydroxyapatite bioceramics with identical microstructure and different macro-porosity, pore size distribution and pore interconnection pathway. The scaffolds were obtained with two different procedures: (a) sponge matrix embedding (scaffold A), and (b) foaming (scaffold B). Bone ingrowth within the two bioceramics was obtained using an established model of in vivo bone formation by exogenously added osteoprogenitor cells. The histological analysis of specimens at different time after in vivo implantation revealed in both materials a significant extent of bone matrix deposition. Interestingly enough, scaffold B allowed a faster occurrence of bone tissue, reaching a steady state as soon as 4 weeks. Scaffold A on the other hand reached a comparable level of bone formation only after 8 weeks of in vivo implantation. Both scaffolds were well vascularised, but larger blood vessels were observed in scaffold A. Here we show that porosity and pore interconnection of osteoconductive scaffolds can influence the overall amount of bone deposition, the pattern of blood vessels invasion and finally the kinetics of the bone neoformation process.

Animals↗

PubMed2005

GABAB receptor intracellular trafficking after internalization in Paramecium.

The number of neurotransmitter receptors on the plasma membrane is regulated by the traffic of intracellular vesicles. Golgi-derived vesicles provide newly synthesized receptors to the cell surface, whereas clathrin-coated vesicles are the initial vehicles for sequestration of surface receptors, which are ultimately degraded or recycled. We have previously shown that GABAB receptors display a punctuate vesicular pattern dispersed on the cell surface and throughout the cytoplasm and are internalized via clathrin-dependent and -independent endocytosis. Here we have studied constitutive GABAB receptor trafficking after internalization in Paramecium primaurelia by confocal laser scanning microscopy and multiple immunofluorescence analysis. After internalization, receptors are targeted to the early endosomes characterized by the molecular markers EEA1 and rab5. Some of these receptors, destined for recycling back to the plasma membrane, traffic from the early endosomes to the endosomal recycling compartment that is characterized by the presence of rab4-immunoreactivity (IR). Receptors that are destined for degradation exit the endosomal pathway at the early endosomes and traffic to the late endosome-lysosome pathway. In fact, some of the GABAB-positive compartments were identified as lysosomal structures by double staining with the lysosomal marker LAMP-1. GABAB vesicle structures also colocalize with TGN38-IR and rab11-IR. TGN38 and rab11 are proteins found in association with post-Golgi and recycling endosomes, respectively.

Animals↗

PubMed2005

A simple non invasive computerized method for the assessment of bone repair within osteoconductive porous bioceramic grafts.

Single energy X-ray imaging, due to its low cost and flexibility, is one of the most used and common technique to assess bone state and bone remodeling over time. Standardized X-ray images are needed to compare sets of radiographs for semi-quantitative analyses of tissue remodeling. However, useful mathematical modeling for the analysis of high level radiographic images are not easily available. In order to propose a useful evaluation tool to a wide clinical scenario, we present an innovative calibration algorithm for a semi-quantitative analysis of non-standardized digitized X-ray images. For calibration on a unique standardization scale, three time invariant regions (ROI) of radiographs were selected and analyzed. The accuracy of the normalization method for X-ray films was successfully validated by using an aluminum step wedge for routine X-ray exposures as tool to standardize serial radiographs (Pearson correlation test: R(2) = 0.96). This method was applied to investigate the progression of the new bone deposition within ceramic scaffolds used as osteoconductive substitute in large bone defects taking advantage of a large animal model. This innovative image-processing algorithm allowed the identification and semi-quantification of the bone matrix deposited within the implant. The osteo-integration at the bone-implant interface was also investigated. A progressively increasing bone tissue deposition within the porous bioceramic implant and a progressive osteo-integration was observed during the 12 months of the trial.

Absorptiometry, Photon↗

PubMed2005

An integrated environment for plastic surgery support: building virtual patients, simulating interventions, and supporting intraoperative decisions.

In the last decade a number of environments for Computer Supported Plastic Surgery have been presented. Nevertheless, an overall approach for training and intraoperative support is still missing or has not been widely exploited yet. We developed a fully integrated system which allows surgical simulation, planning, and support for computer-guided plastic surgery procedures starting from image acquisition to final intraoperative assistance. The system also provides the user with a radiological workstation able to analyse patient medical images and case studies, with advanced bidimensional and three dimensional image processing functionalities. We intend to demonstrate that such a platform can be built at an affordable cost. The radiological workstation is capable of supporting radiologists and surgeons in real patient case studies and the simulation workstation may be adopted by plastic surgeons in teaching and training of complex surgical planning. Moreover, results of simulation can be used in the operating room with a relatively high benefit in terms of improved accuracy, reduction of surgical risks, and decrease in training costs.

Decision Support Techniques↗

PubMed2005

Simulation of the biomechanical behavior of the skin in virtual surgical applications by finite element method.

The objective of this study was to develop a software application that is able to support plastic surgeons interested in applying simulations and soft tissue modeling during presurgical planning activities. By using our user-friendly interface and force-displacement graphs, users can analyze scalp skin behaviors when subjected to stress. Users can 1) determine the dynamic of a general point of scalp skin after the application of a specific force, 2) predict the force needed for displacement of a point, and 3) study the deformation of all the points of the entire scalp based on the force applied. Results showed how users are able to manipulate and analyze mechanical behaviors on a mechanical model rather than on a pure geometric qualitative physiological model. The entire application was developed on a Silicon Graphics workstation.

Animals↗

PubMed2004

GABAA receptor subunits identified in Paramecium by immunofluorescence confocal microscopy.

The presence of opioid, beta-adrenergic and cholinergic receptors has been demonstrated in ciliated protozoa, but little is known about gamma-aminobutyric acid (GABA) receptors. In this study we have analyzed the distribution of GABA(A)-type receptor subunits in Paramecium. Confocal laser microscopy using antibodies specific for alpha(1)-, alpha(2)-, alpha(3)-, alpha(6)-, beta(2/3)-, gamma(2)-, epsilon-, lambda-, and theta-subunits showed that most receptors are aggregated in clusters and are distributed both on cell surface and in the cytoplasm. The intensity of labelling of the alpha(6)-, beta(2/3)- and gamma(2)-subunits was more intense than the alpha(1)-, epsilon-, and theta-subunits, suggesting that the former are present in higher concentrations than the latter.

Animals↗

PubMed2003

Swimming behavior regulation by GABAB receptors in Paramecium.

In Paramecium, internal Ca(2+) concentration increase coupled to membrane depolarization induces a reversal in the direction of ciliary beating and, consequently, a reversal in swimming direction. The ciliary reversal (CR) duration is correlated to Ca(2+) influx, and the addition of drugs that block the Ca(2+) current leads to a reduction in the backward swimming duration. In this study we have examined the possible function of GABA(B) receptors in P. primaurelia swimming control. The presence of GABA(B) immunoanalogue in Paramecium was evidenced using SDS-PAGE, Western blotting, and confocal laser scanning microscopy. By applying the specific GABA(B) receptor agonist baclofen, a dose-dependent inhibition of the membrane depolarization-induced CR duration was observed. This inhibition was antagonized by phaclofen, persisted when K(+) channel blockers were applied, and disappeared after treatment with nifedipine and verapamil. Moreover, the action of baclofen on depolarization-induced CR was suppressed by treatment with pertussis toxin. Therefore, these experiments suggest that baclofen modulates CR by a G protein (G(0) or G(1)) mediated inhibition of dihydropyridine-sensible calcium channels. Finally, synthesis and release of GABA in the environment by Paramecium have been demonstrated by HPLC. Possible correlations between GABA(B) receptor activation and the regulation of intracellular Ca(2+) levels are discussed.

Animals↗

PubMed2003

Neuroscience data and tool sharing: a legal and policy framework for neuroinformatics.

The requirements for neuroinformatics to make a significant impact on neuroscience are not simply technical--the hardware, software, and protocols for collaborative research--they also include the legal and policy frameworks within which projects operate. This is not least because the creation of large collaborative scientific databases amplifies the complicated interactions between proprietary, for-profit R&D and public "open science." In this paper, we draw on experiences from the field of genomics to examine some of the likely consequences of these interactions in neuroscience. Facilitating the widespread sharing of data and tools for neuroscientific research will accelerate the development of neuroinformatics. We propose approaches to overcome the cultural and legal barriers that have slowed these developments to date. We also draw on legal strategies employed by the Free Software community, in suggesting frameworks neuroinformatics might adopt to reinforce the role of public-science databases, and propose a mechanism for identifying and allowing "open science" uses for data whilst still permitting flexible licensing for secondary commercial research.

Computational Biology↗

PubMed2003

A virtual reality system for the training of volunteers involved in health emergency situations.

In order to guarantee an effective and punctual medical intervention to injured people involved in health emergency situations, where usually both professional and non-professional health operators are involved, a fast and accurate treatment has to be carried out. In case of catastrophic or very critical situations, non-professional operators who did not receive proper training (volunteers are among them) could be affected by psychological inhibitions. Their performances could slow down in such way that would affect the quality of the treatment and increase both direct and indirect costs. Our virtual reality system that is currently in use at the health care emergency center of San Martino Hospital in Genoa, Italy, has been designed and developed to check health emergency operators' capabilities to adopt correct decision-making procedures, to make optimal use of new technological equipment and to overcome psychological barriers. Our system is composed of (1) a high-end simulation PC, whose main functions are execution of the main software module, rendering of 3D scenes in stereo mode, rendering of sound, and control of data transmission from/to VR devices; (2) a low-end control PC, which controls the VR simulation running on the simulation PC, manages medical emergency simulation scenarios, introduces unexpected events to the simulation and controls the simulation difficulty level; (3) a magnetic-based motion tracking device used for head and hand tracking; (4) a wireless pair of shutter glasses together with a cathode ray tube wall projector; and (5) a high-end surround sound system. The expected benefits have been verified through the design and implementation of controlled clinical trials.

Clinical Trials as Topic↗

PubMed2002

Fluorescence microscopy imaging of bone for automated histomorphometry.

We have developed a computer-based method for the automated quantification of bone tissue in histological sections of decalcified specimens. Bone tissue was generated by ectopic implantation of ceramic-based carriers loaded with human bone marrow stromal cells (BMSCs). The method is based on the acquisition of multimodal images, in order to identify and measure the area covered by bone tissue (using fluorescent light) and the total area of tissue (using transmitted light), thereby excluding the regions corresponding to nonresorbed scaffold. The amount of bone as a percentage of the total area of interest (bone/area) and of the newly formed tissue (bone/tissue) is automatically derived. The computer-based results correlated closely with those obtained by manual identification of bone and tissue areas in the same histological fields (R(2) = 0.997; p < 0.0005), with errors dependent on the magnification used but always lower than 9.4%. The method was used to compare the bone/tissue and bone/area percentages in samples of engineered bone based on human BMSCs expanded in the presence of different biochemical factors and loaded onto different scaffolds. The technique thus represents a valuable tool to quantify reproducibly, accurately, and easily bone formation in a variety of tissue-engineering studies.

Bone Marrow Cells↗

PubMed2002

Neuroinformatics: the integration of shared databases and tools towards integrative neuroscience.

There is significant interest amongst neuroscientists in sharing neuroscience data and analytical tools. The exchange of neuroscience data and tools between groups affords the opportunity to differently re-analyze previously collected data, encourage new neuroscience interpretations and foster otherwise uninitiated collaborations, and provide a framework for the further development of theoretically based models of brain function. Data sharing will ultimately reduce experimental and analytical error. Many small Internet accessible database initiatives have been developed and specialized analytical software and modeling tools are distributed within different fields of neuroscience. However, in addition large-scale international collaborations are required which involve new mechanisms of coordination and funding. Provided sufficient government support is given to such international initiatives, sharing of neuroscience data and tools can play a pivotal role in human brain research and lead to innovations in neuroscience, informatics and treatment of brain disorders. These innovations will enable application of theoretical modeling techniques to enhance our understanding of the integrative aspects of neuroscience. This article, authored by a multinational working group on neuroinformatics established by the Organization for Economic Co-operation and Development (OECD), articulates some of the challenges and lessons learned to date in efforts to achieve international collaborative neuroscience.

Computational Biology↗

PubMed2002

WEB-WAP based telecare.

We have developed two telecare applications based on mobile telephony (WAP) and WEB. The first can be used to request Basic Life Support (BLS) guidelines any time by using a WAP device and to teach people and non-professionals involved in health care emergency situations. The second is a WEB-WAP based tool for medical data retrieval and at-home health care monitoring of chronically ill patients with congestive heart failure (CHF) or diabetes. Medical education content related to these diseases is available on the WEB and on the WAP device. The WAP application uses the features found in the last generation of mobile phones such as better multimedia information presentations, better interactivity capabilities, and enhanced ease of use. Based on these two applications, a promising platform is offered for developing applications in health care, home care, medical monitoring and health education ensuring continuity of care. In the paper we present the preliminary results of a pilot test at Thessaloniki University (Greece) where the WEB-WAP based tool is used to monitor patients with diabetes or CHF.

Chronic Disease↗