Biomedical subjects

M T Valenti

Publications and source records attributed to M T Valenti.

6 recordsLinked to original sources

PubMed2005

Bone microarchitecture evaluated by histomorphometry.

The increasing use of densitometric devices for assessing bone fragility has progressively strengthened the assumption that mass is the most important property determining bone mechanical competence. Nevertheless, structure and microarchitecture are relevant aspects of bone strength. The study of microarchitecture is based on the measure of width, number, and separation of trabeculae as well as on their spatial organization. There are several methods to assess bone architecture, particularly at the trabecular level. In particular, histomorphometry, based on the use of optical microscopy and on the principles of quantitative histology and stereology, evaluates microarchitecture two-dimensionally, even if these measures appear well correlated to the three-dimensional structure and properties of bone. In addition, new computerized methods allow the acquisition of more sophisticated measurements by means of a digitizer have been introduced to integrate the use of the microscope. These methods supply information on trabecular width as well as on its distribution and on the organization of the trabeculae in the marrow space. Microarchitecture seems to be a determinant of bone fragility independent of bone density and it is important for understanding the mechanisms of bone fragility as well as the action of the drugs used to prevent osteoporotic fractures. Several in vivo studies (on animals and humans) can provide an additional interpretation for the anti-fracture effect of such drugs. For instance, bisphosphonates and parathyroid hormone seem to preserve or even improve microarchitecture. The challenge for the future will be to evaluate bone quality in vivo with the same or better resolution and accuracy than the invasive methods used today.

Animals↗

PubMed2005

Histomorphometric analysis of glucocorticoid-induced osteoporosis.

Bone histomorphometry or quantitative histology consists of counting or measuring tissue components: cells, extracellular constituents and microarchitecture. Bone histomorphometry is the only method that allows the measurement of mineralization rate and the study of bone formation at three levels: cell, remodeling unit and tissue levels. It is a useful tool to explain the pathogenesis and cellular mechanisms of different metabolic bone diseases such as glucocorticoid-induced osteoporosis (GIO). Glucocorticoids (GC) affect calcium and bone metabolism at every level, but the main effect is the osteoblastic dysfunction. Concerning the bone formation, some histomorphometric studies have shown a depressed osteoblastic activity at a cell, bone remodeling unit, and tissue levels. In addition, there is evidence of a shortening of the period in which the osteoblasts work actively forming the bone matrix. This latter effect seems to occur after high cumulative doses of GC. With regard to the resorption, the results are still debated, but histomorphometric parameters seem to be increased in the majority of studies, at least in the first period of the GC treatment. From a structural point of view, GC seem to induce a thinning of the trabeculae without their perforation, which occurs only after high cumulative doses. Anti-resorptive treatments, such as bisphosphonates, are able to counteract the negative effects of GC on bone. In particular, along with their active working period, they prolong the lifespan of osteoblasts and osteocytes. In addition, the anti-resorptive treatments seem to extend the time for secondary mineralization through a reduction of the Activation Frequency. The latter is an intriguing mechanism of bisphosphonates in GIO that needs further ad hoc investigations.

Animals↗

PubMed1998

Differentiation, proliferation and apoptosis levels in human leiomyoma and leiomyosarcoma.

A comparative analysis of the differentiation pattern, the proliferative behaviour, and the level of apoptosis between human benign and malignant neoplasms of smooth-muscle (SM) tissue is lacking. The clinical, histopathological, immunochemical, and immunocytochemical features of leiomyomas (LM) and leiomyosarcomas (LMS) were investigated by a panel of monoclonal antibodies specific for some differentiation markers of SM tissue (SM myosin and alpha-actin, desmin, and SM22) and for markers of non-muscle tissue (vimentin and non-muscle myosin). Proliferating normal and neoplastic cells were identified by proliferating-cell nuclear antigen (PCNA)/Ki67 immunostainings and the apoptotic cells were revealed by means of the terminal-deoxynucleotidyltransferase-mediated dUTP nick-end labelling technique. Gel electrophoresis and Western blotting, performed with anti-(SM1/SM2 myosin isoform) antibody, indicated quantitative differences between LMS and LM, which mirrored higher positive to negative nuclear ratios for PCNA, Ki67 and apoptosis in malignant as opposed to benign neoplasms. With LM, however, a similar SM1 to SM2 ratio could be associated with different proliferation levels. Uterine, gastric and intestinal LMS displayed specific patterns of SM1/SM2 and/or non-muscle myosin expression that were not paralleled by different levels of proliferation/apoptosis. While the level of PCNA/Ki67 correlated with the level of apoptosis in normal SM tissues and LM, that of LMS did not. In vivo at the cellular level, LM and uterine LMS displayed a near-uniform SM tissue differentiation, whereas the other LMS displayed a lesser or a heterogeneous immunoreactivity. In vitro, cultured LMS cells showed a limited and peculiar expression of SM myosin. In conclusion, there is no reciprocal relationship between degree of differentiation and the level of proliferation, as exemplified by the finding that the less differentiated intestinal LMS displays the lowest proliferative behaviour and that the relatively more differentiated gastric LMS/metastasis is more proliferative.

Aged↗

PubMedDate not supplied

Conditioned medium from MCF-7 cell line induces myofibroblast differentiation, decreased cell proliferation, and increased apoptosis in cultured normal fibroblasts but not in fibroblasts from malignant breast tissue.

We studied the effect of conditioned medium (CM) obtained from cultures of oestrogen-receptor positive breast cancer MCF7 cell line on the differentiation, proliferation and apoptosis patterns of cultured breast fibroblasts from normal interstitial and malignant stromal tissue. Fibroblasts were grown in the presence or absence of CM and examined for the differentiation pattern by immunofluorescence and Western blotting procedures, for proliferation profile by Ki67 expression, and for apoptosis by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling technique. Monoclonal antibodies specific for non-muscle (NM), smooth muscle (SM) lineage and differentiation markers were applied to these cultures. CM is able to induce a SM-like differentiation in interstitial fibroblasts, i.e., essentially myofibroblast formation. Fibroblasts from tumour stroma showed the presence of a small number of smooth muscle cells (SMC) along with a large number of myofibroblasts. Treatment of these cultures with CM was unable to change this pattern. Only normal fibroblasts were responsive to the proliferation/apoptotic-inhibitory effect of the CM. These data suggest that structural and functional differences exist between stromal fibroblasts from normal breast and breast cancer with respect to the responsiveness to soluble factors present in the CM. We hypothesize that the lack of in vitro sensitivity to CM shown by 'tumour' fibroblasts is the result of an in vivo inherent and stable phenotypic change on the fibroblasts surrounding breast tumour cells occurring via a paracrine mechanism.

Apoptosis↗

PubMedDate not supplied

A new nested primer pair improves the specificity of CK-19 mRNA detection by RT-PCR in occult breast cancer cells.

Reverse transcription polymerase chain reaction (RT-PCR) of cytokeratin-19 (CK-19) has been widely used to detect small numbers of circulating malignant epithelial cells in the bone marrow or the peripheral blood of patients with breast cancer. However, a high percentage of false positive results has been recorded and conflicting reports question the clinical relevance of this technical approach. We demonstrate that the use of a new nested primer pair for CK-19 RT-PCR avoids false positive results without affecting the sensitivity of the assay. Our experiments were carried out using MCF-7 cells alone or mixed with peripheral blood mononuclear cells (PBMNC) of healthy donors. The results were also validated in a large series of healthy donors and in a preliminary study on a limited number of patients with breast cancer, thus suggesting that our assay is feasible for application in the clinical evaluation of occult malignant epithelial cells.

Adult↗

PubMedDate not supplied

HLA expression in type II mixed cryoglobulinemia and chronic hepatitis C virus.

OBJECTIVE: Hepatitis C virus infection is closely associated not only with hepatic damage, but also with mixed cryoglobulinemia (MC) and other autoimmune and lymphoproliferative disorders. Because HCV is both hepatotropic and lymphotropic, the aim of this study was to investigate whether the genetic background may influence the clinical pattern seen in different patients. METHOD: Two groups of patients with HCV infection were studied: 16 with type II MC and 18 with chronic active hepatitis (CAH). 120 bone marrow donors were considered as the control group. In all patients HLA-A-B-C antigens were evaluated using the microlymphocytoxicity technique, and HLA-DR by the PCR-SSP method. RESULTS: The frequency of the HLA antigens expressed was not precisely defined in the two groups. However, the HLA-B51 and B35 antigens, which are often correlated with autoimmune disorders, were highly expressed in the MC patients (31.2%) compared to the controls (6.9%) and to the CAH group (11%). Moreover, HLA-A9 with its split A24 were present in 50% of the MC patients. More interesting was the expression of the HLA-DR7 antigen, which was found only in the CAH group, suggesting that it may influence the specific liver involvement in HCV infections. CONCLUSION: These findings indicate that the HLA system may play an important role in the clinical manifestations of HCV infection.

Adult↗