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Biomedical subjects

A Piattelli

Publications and source records attributed to A Piattelli.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

The human multidrug resistance gene (MDR-1): immunocytochemical detection of its expression in oral SCC.

A large number of oral cancer patients show poor or partial response to chemotherapy and the mechanisms are poorly understood. At present, an MDR-1 product, the P-170 glycoprotein, is the best known of the P-170 family and is involved in resistance to natural product-based chemotherapeutics, including taxanes, anthracyclines, vinca alkaloids, podophyllotoxins and camptothecins. Although several reports suggest that P-170 is clinically relevant in haematological malignancies, its role in solid tumours is not well understood. Its overexpression has been found to be correlated with the poor outcome observed in patients treated with chemotherapy and presenting drug resistance. The aim of this study was to detect the protein expression patterns of MDR-1 product by immunohistochemistry in formalin-fixed-paraffin-embedded tissues. For these reasons, 30 oral SCC and 6 healthy oral mucosa specimens were tested with anti-P-170 antibodies using standard streptavidin-biotin-peroxide technique. Immunohistochemistry demonstrated that 4 cases (66.6%) of normal oral mucosa and 24 cases (80%) of oral SCC showed positivity. Four cases (13.4%) showed strong positivity in tumour areas and complete negativity in normal epithelial cells adjacent to the tumour. No staining was observed in stromal structures, with the exception of the lymphocytic compartment that showed a strong staining as reported in literature for CD56+ and CD8+ cells. Four G1 tumours (33%) and 2 G3 tumour (33%) showed strong positivity in areas with a higher degree of differentiation. P-170 positivity in normal epithelial cells of smoker patients, in differentiated area of neoplasia and negativity or zonal positivity in undifferentiated area of tumour suggested that activation of the MDR-1 gene or selection of intrinsically multidrug resistance neoplastic cells may occur at early stages of tumorigenesis of oral cancers, before the real evidence of cellular transformation. Thus the contact with possible chemical carcinogens, such as those of tobacco smoke, may induce activation of MDR-1 gene. This study was conducted only on untreated carcinomas so for this reason it cannot indicate the real incidence of acquired multidrug resistance. The data of MDR-1 product expression by immunohistochemistry in oral SCC might suggest that an overexpression of this protein could constitute a hallmark of potential more aggressive phenotype for this type of neoplasia and a rapid method for pre-screening tumours for a constitutive multidrug resistance in order to orientate the cancer treatment.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Surface analysis of machined versus sandblasted and acid-etched titanium implants.

Initially, implant surface analyses were performed on 10 machined implants and on 10 sandblasted and acid-etched implants. Subsequently, sandblasted and acid-etched implant cytotoxicity (using L929 mouse fibroblasts), morphologic differences between cells (osteoblast-like cells MG63) adhering to the machined implant surfaces, and cell anchorage to sandblasted and acid-etched implant surfaces were evaluated. Results indicated that acid etching with 1% hydrofluoric acid/30% nitric acid after sandblasting eliminated residual alumina particles. The average roughness (Ra) of sandblasted and acid-etched surfaces was about 2.15 microns. Cytotoxicity tests showed that sandblasted and acid-etched implants had non-cytotoxic cellular effects and appeared to be biocompatible. Scanning electron microscopic examination showed that the surface roughness produced by sandblasting and acid etching could affect cell adhesion mechanisms. Osteoblast-like cells adhering to the machined implants presented a very flat configuration, while the same cells adhering to the sandblasted and acid-etched surfaces showed an irregular morphology and many pseudopodi. These morphologic irregularities could improve initial cell anchorage, providing better osseointegration for sandblasted and acid-etched implants.

Acid Etching, Dental↗
PubMedDate not supplied

Microvessel density (MVD) and vascular endothelial growth factor expression (VEGF) in human oral squamous cell carcinoma.

BACKGROUND: Carcinogenesis is thought to be dependent on neovascularization. Vascular endothelial growth factor (VEGF) is a glycoprotein that has the capability of increasing vascular proliferation and permeability. VEGF has been found to be expressed in several different types of tumours and it may contribute to the progression of malignant tumours. Increased microvessel density (MVD) has been described in oral squamous cell carcinoma (OSCC) and seems to be related to patient prognosis. MATERIALS AND METHODS: Fifty-two cases of OSCC were evaluated in the present study. Immunostaining for VEGF and Factor-VIII was performed. The MVD was evaluated in G1, G2 and G3 tumours. RESULTS: The differences between these 3 groups were statistically significant (p = 0.0331). MVD was also evaluated in lymph-node negative and lymph-node positive cases: the differences between these two groups were statistically significant (p < 0.0001). VEGF expression was evaluated in G1, G2 and G3 tumours. The differences between the 3 groups were not statistically significant (p = 0.289), even if an increasing trend in the VEGF positivity was evident from G1 to G3. The difference of VEGF expression between tumours with and without lymph node metastases was not significant (p = 0.196). No correlation was present between intensity of VEGF positivity and histological grading or lymph-node status and between VEGF and MVD. CONCLUSION: Our data showed that MVD was correlated with grading and lymph-node status, while no similar correlation was found for VEGF.

Adult↗
PubMedDate not supplied

Vascular endothelial growth factor and microvessel density around healthy and failing dental implants.

Inflammatory infiltrate may be important in the evolution of inflammatory processes involving peri-implant tissues. Angiogenesis is an important feature of inflammation and healing, but its role in the development and progression or in the healing of periodontal lesions has not been elucidated. Vascular endothelial growth factor (VEGF) is a potent inducer of endothelial cell proliferation. The aim of the present study was to conduct a comparative immunohistochemical evaluation of VEGF and microvessel density (MVD) in normal keratinized gingiva and in peri-implant soft tissues surrounding failing implants. Fifteen patients participated in this study. Ten biopsies were taken from healthy keratinized gingiva, and 10 were taken from peri-implant soft tissues surrounding failing non-submerged implants. In healthy sites, the endothelial lining cells of the vessels always tested positive for VEGF; also, VEGF intensity was high in most cases. Stromal cells were positive for VEGF in 70% to 90% of samples. The MVD was 60.250 +/- 5.123. In peri-implantitis samples, the cells of the inflammatory infiltrate were positive for VEGF in 80% to 100% of cases, and the VEGF intensity was low in all cases. The stromal cells were positive for VEGF in 90% to 100% of cases, and in most cases the intensity was low. The MVD was 101.800 +/- 11.256. The difference in MVD between healthy sites and peri-implantitis was statistically significant (P = .0158). Expression of VEGF was lower in peri-implantitis samples, and this difference was statistically significant (P = .0373). Because of its extensive presence, VEGF is probably a factor in both the maintenance of periodontal physiology and in the progression of peri-implant inflammatory disease.

Adult↗
PubMedDate not supplied

Interaction between bcl-2 and P53 in neoplastic progression of basal cell carcinoma of the head and neck.

BACKGROUND: Basal cell carcinoma (BCC) is the most frequent tumor of the human skin and generally shows a favourable clinical behaviour. However, a percentage of BCC grows aggressively, infiltrating contiguous structures, sometimes giving distant metastases. MATERIALS AND METHODS: Bcl-2 and p53 protein expression was studied immunohistochemically in 60 cases of BCC (30 non-aggressive, BCC1 and 30 aggressive cases, BCC2) of the head and neck region with a complete clinical follow-up. RESULTS: All the BCC1 showed distinct cytoplasmic staining for bcl-2. The intensity of staining ranged from intermediate to high, with only three cases showing low positivity. Among BCC2, none of the 30 cases showed positivity for bcl-2. Bcl-2 expression was directly correlated with the BCC1 sub-type and a favourable clinical follow-up (p<0.01). Among BCC1, 27 cases were found negative for p53 protein expression while 3 exhibited only a low immunoreactivity. Among BCC2, 11 out of 30 cases showed an intermediate immunoreactivity, and 18 out of 30 exhibited high positivity for p53 protein. The expression of p53 protein correlated inversely with cellular differentiation (p<0.01). CONCLUSION: From the analysis of these results it is reasonable to consider bcl-2 and p53 protein expression as useful discriminating prognostic factors in the evaluation of BCCs of the head and neck region. In fact, the finding of clones expressing bcl-2 in a case of BCC may be indicative of an "indolent" cellular neoplastic phenotype. In other words, bcl-2 could be used as a "clonal marker" of a still favourable clinical behaviour. Conversely, the partial or complete loss of bcl-2-bearing neoplastic clones during histological transformation, with the appearance of clones expressing p53 protein in a BCC could be considered a hallmark of transition from a low-to high-grade malignancy, characterized by the emergence of cellular clones with a more aggressive phenotype, responsible for worse clinical behaviour.

Adult↗
PubMedDate not supplied

[Apicoectomy].

Explore the source record for details and available documents.

Apicoectomy↗
PubMedDate not supplied

Calcifying odontogenic cyst associated with compound odontoma: a study on undemineralized material.

In a minority of cases of calcifying odontogenic cyst (COC) it is possible to observe the formation of dental hard tissues in the cyst wall. The use of undemineralized sections has allowed an evaluation of the mineralized tissues normally lost with the use of demineralizing agents. All the dental hard tissues presented a high degree of morpho- and histodifferentiation. The histochemical staining for calcium salts (von Kossa) showed the presence of areas of low mineralization in the portion of the lesion, where the tissue maturation was not complete. In conclusion the appearance of the dental hard tissues in this case of compound odontoma arising in the cyst wall of a COC is similar to that already described in compound odontoma not associated with COC.

Adult↗
PubMedDate not supplied

Ultrastructural analysis of periapical granulomas.

A large portion of periapical granulomas is composed by cells of the mononuclear-phagocyte and lymphoid system. The ultrastructural features of the monocytes/macrophages differ in relationship to the state of activity of the cells (phagocytosis or secretion). A close correlation between cells of these two systems can be surmised by their tight contacts. An important role in the bone resorption is probably played by cytokines like IL-1 and TNF.

Humans↗
PubMedDate not supplied

Histochemical and laser scanning microscopy characterization of the hydroxyapatite-bone interface: an experimental study in rabbits.

An experimental study was done in rabbits to characterize the bone-hydroxyapatite (HA) interface by the use of histochemical staining for mineralized tissue and laser scanning microscopy (LSM) on undemineralized sections. Twenty HA-coated Sustain implants were placed in rabbit femurs and retrieved after 6 months. The specimens were then processed to obtain thin ground sections. In all specimens, there was intimate contact between bone and HA. In some portions, mineralized bone was in tight, direct contact with the HA, while in other portions, a basophilic unmineralized material was present between bone and HA. This material was thicker in areas with active bone formation upon the HA surface and had staining characteristics similar to the material present around the osteocyte lacunae. LSM showed a fluorescence present in many areas of the interface, in osteocyte lacunae, and inside the coating. An organic bonding between bone and HA can probably be hypothesized.

Animals↗
PubMedDate not supplied

Light and laser scanning microscopy analysis of hydroxyapatite used in periodontal osseous defects in man: evidence of a different resorption pattern in bone and soft tissues.

Hydroxyapatite (HA) is a highly biocompatible material that recently has been shown to undergo biodegradation. The mechanisms of this phenomenon are unclear, and humoral and cellular events have been thought to be implicated. In the present study HA particles were put into infraosseous defects on teeth that were to be extracted for prosthetic reasons and then retrieved after a 1-year period. The specimens were processed with the cutting grinding system. Results show a very sharp difference of the biodegradation processes, related to the tissues that surround the HA particles. HA in tight contact with mineralized bone showed no evidence of degradation or resorption, while on the contrary, in the areas where bone loose connective tissue was present, it was possible to observe HA crystals detached and scattered in cells cytoplasm or extracellular fluids. This dissolution and resorption phenomenon were observed also by Laser Scanning Microscope (LSM) in fluorescent mode. These differences in degrees of degradation between bone and loose connective tissue could be due to the small amount of interstitial fluid present in mineralized bone and the greater flow of fluid through connective tissue.

Biodegradation, Environmental↗
PubMedDate not supplied

Guided bone regeneration using resorbable and nonresorbable membranes: a comparative histologic study in humans.

Resorbable membranes of poly(lactic acid) and poly(glycolic acid) (PLA/PGA) were compared to nonresorbable expanded polytetrafluoroethylene (e-PTFE) membranes in the treatment of defects around titanium dental implants placed in postextraction sockets. Two partially edentulous and three completely edentulous patients requiring implant-supported restorations participated. Sixteen Brånemark implants were placed into extraction sockets and covered with modified titanium cover screws, called harvest cover screws, which allow tissue biopsy at second-stage implant surgery. Seven defects were treated with PLA/PGA membranes, five were treated with e-PTFE membranes, and four were left untreated (control sites). After 6 months of healing, the harvest cover screws were retrieved and processed for light microscopy examination together with the regenerated tissues. Very little or no bone formation was detected in control specimens. The e-PTFE membranes were found to be the most effective barrier material, in that denser and a greater amount of regenerated bone was found. The PLA/PGA membranes produced some bone regeneration when compared to control sites, but to a lesser extent compared to e-PTFE sites.

Adult↗
PubMedDate not supplied

Histologic analysis of the interface of a titanium implant retrieved from a nonvascularized mandibular block graft after a 10-month loading period.

The combined use of bone grafts and osseointegrated implants appears to improve the long-term prognosis of transplanted bone. One question pertaining to the use of grafted bone is whether the biologic reaction to implants placed in grafted bone is the same as that seen under nongrafted conditions. A mandibular discontinuity defect in a 63-year-old female patient was repaired with a nonvascularized block graft into which 3 titanium implants were placed. After a 10-month loading period, one of the implants was retrieved and treated to obtain thin ground sections. The histologic examination showed mature bone in close contact with the implant surface; no gaps, fibrous tissue, or inflammatory cells were seen at the interface. No resorption phenomena were present. The bone at the interface was highly mineralized. The features of the regenerated bone and the bone-implant interface in grafted bone were similar to those seen in nongrafted situations; no differences were found with results presented in the literature concerned with retrieved implants placed into vascularized grafts.

Bone Regeneration↗
PubMedDate not supplied

Clinical and histologic features of a nonaxial load on the osseointegration of a posterior mandibular implant: report of a case.

The authors report on the clinical and histologic features of a single implant replacing a mandibular molar, which fractured after a 1-year loading period. Because of anatomic factors, the implant had been placed in an angulated position. The histologic examination showed a very high percentage of bone-implant contact. The bone located at the interface with the implant was mature, compact, and had few marrow spaces. No resorption areas were present, and no connective tissue was seen at the interface. Most likely, the lateral nonaxial forces exerted on the implant created very high bending moments. These forces produced a fracture of the implant, although no loss of osseointegration was observed at the interface.

Adult↗