Biomedical subjects

Patrizia D'Amelio

Publications and source records attributed to Patrizia D'Amelio.

5 recordsLinked to original sources

PubMed2006

Immune system and bone metabolism: Does thymectomy influence postmenopausal bone loss in humans?

Recent studies of animal models have suggested that an increase in the number of T cells due to both peripheral expansion and increased thymic T cell output plays a key role in the regulation of bone loss after ovariectomy. Osteoclastogenic cytokines which are either produced by T cells or activate T cells have also been implicated in ovx induced bone loss. Among them are TNF alpha and IL-7. The present study investigates the role of thymectomy (THX) and IL-7 in bone metabolism in humans. We studied T cells subsets, cytokine production and bone metabolism in 13 women thymectomized for Myasthenia gravis as compared to healthy controls. Our data demonstrate that the number of CD4+ and TNF-producing T cells is lower in THX women as compared to euthymic controls. However in THX women the residual T cells produce higher levels of IL-7 and RANKL. Furthermore, flow cytometry shows that IL-7 is produced by T and B cells. Serum levels of TNF alpha were unaffected by THX and both serum TNF alpha and the RANKL/OPG correlated inversely with BMD. There were no differences in bone turnover and bone mineral density between THX women and the controls. These data suggest that THX decreases the number of TNF-producing CD4+ T cells but does not alters serum TNF levels. The RANKL/OPG ratio and indices of bone metabolisms are also not affected by THX, although THX increases the levels of IL-7 and RANKL. Further studies are needed to clarify the role of thymus in bone metabolism and osteoclastogenesis in postmenopausal women.

Adolescent↗

PubMed2006

Cross-sectional geometrical properties of distal radius and ulna in large, medium and toy breed dogs.

Fractures of the distal radius and the ulna are the third most common fractures in dogs. Toy and miniature breeds have a propensity to develop antebrachial fractures after falling or jumping. Most affect the distal third of both bones involving between 15% and 37% of the radial length. Larger dogs, instead, typically sustain hyperextension injuries to the carpus. The causative mechanisms for this fracture prevalence in toy dogs are unknown. Breed-related changes in bone geometry and/or mineral density have been suggested as possible etiologic factors. In a multifactorial study, the main etiological factors potentially responsible for determining susceptibility to fractures in toy breeds are considered. The aim of this first study is to evaluate the geometric bone features in different dog sizes. The cortical bone cross-sectional properties along the length of the right radius and the ulna of 28 dogs from three different size categories have been quantified by computerized tomographic scanning. Geometrical cross-sectional parameters were measured and normalized to radial length to allow intergroup comparisons. Discriminant analysis was used to classify the observations into different groups. Through statistical analysis of the normalized values, significant differences in cross-sectional properties of different bone sizes were found. The results suggest that, when proportionally loaded, the antibrachii of toy breed dogs are more susceptible to fracture than those of large breed dogs due to morphological differences.

Anatomy, Cross-Sectional↗

PubMed2004

Spontaneous osteoclast formation from peripheral blood mononuclear cells in postmenopausal osteoporosis.

Osteoclasts are cells involved in bone reabsorbing and hence in postmenopausal bone loss. There is no evidence of increased in vitro spontaneous osteoclast formation in postmenopausal osteoporosis. The aim of our study was to evaluate spontaneous osteoclastogenesis in osteoporosis. Bone mineral density, markers of bone turnover, and cultures of peripheral blood mononuclear cells (PBMC) on dentine slices with or without the addition of 1,25-OH vitamin D3 ([10(-8) M]) were obtained from 18 osteoporotic women and 15 controls. To verify cytokine production by PBMC cultures, supernatants were collected on days 3 and 6 and tested for TNF-alpha and RANKL. The data obtained were compared between patients and controls by one-way ANOVA and correlated by Pearson's coefficient. We found a significant increase in osteoclast formation and bone reabsorbing activity in patients with respect to controls; in addition, the production of TNF-alpha and RANKL is significantly higher in patients. Furthermore, osteoclast number is inversely correlated with bone mineral density and directly with RANKL in culture supernatants. Our data demonstrated an increased spontaneous osteoclastogenesis in women affected by postmenopausal osteoporosis: this increase may be explained by the higher production of TNF-alpha and RANKL by PBMC cultures of osteoporotic patients.

Bone Density↗

PubMed2002

Densitometric study of human developing dry bones: a review.

In this article we describe the use of dual-energy X-ray absorptiometry (DXA) technique in the study of fetal and infant bone development. In particular, we review the results of densitometric studies on human developing dry bones such as spine, femur, and mandible; these data are compared with the results obtained with other methods used in the past. In particular DXA technique applied in dry is able to detect the first appearances of the ossification centers; show individual variability of bone mineral density yet during the prenatal life; and determine the correlation between bone mineral density and the variation of mechanical loading.

Absorptiometry, Photon↗

PubMed2002

Densitometric study of dry human mandible.

The purpose of this study was to evaluate the variability of bone density among three zones of adult human dry mandible and its relationship to age, gender, and dental status. Thirty-one dried mandibles (16 female ranging between 23 and 82 yr and 15 male ranging between 34 and 85 yr; 6 samples completely edentulous and 6 edentulous only in the molar-premolar zone) were analyzed by a Hologic QDR 1000 X-ray densitometer according to three zones: the ramus, the molar-premolar zone, and the incisor-canine zone. We found a significant inverse correlation between bone density of the ramus and age (r = 0.41, p = 0.02). The bone density of the incisor-canine zone was higher than the density of the other zones; males had a higher bone density than females in all zones analyzed. Our data suggest that mandibular bone density is influenced by age and gender in different ways according to the specific mandibular portion considered, whereas the dental status does not seem to influence mandibular bone density.

Adult↗