We investigated the relative contribution of the major factors regulating calcium homeostasis in determining the circulating levels of PTH. We studied 137 males and 125 females who were healthy ...volunteers. Circulating PTH levels were determined by three different immunoradiometric assays (IRMA). The first one (PTH Sorin, PTH S) utilizes two affinity-purified polyclonal antibodies directed against the 1-34 and 39-84 sequence of the hormone. The two other IRMA share polyclonal anti-PTH (39-84) antibodies. The first assay (PTH Whole, PTH W) utilizes a second polyclonal antibody, directed against the 1-4 amino acid sequence. The second assay (PTH Total, PTH T) utilizes a second antibody specific for the 7-34 region. Concentrations of PTH fragments lacking the initial amino acid sequence (PTH N-truncated, PTH N-t) were determined by the difference of values between PTH T and PTH W. Vitamin D was the main explicative variable almost in every multiple linear regression model, both considering the group as a whole (PTH S: R2 = 0.238, P < 0.0001; PTH W: R2 = 0.08, P < 0.001; PTH T: R2 = 0.145, P < 0.0001; PTH N-t: R2 = 0.081, P < 0.009) and when considering men and women separately. In subjects with vitamin D insufficiency (n = 53) 25(OH)D < 30 nmol/l, mean serum levels of parathyroid hormone were significantly higher (P < 0.001) than those in subjects of similar age with normal vitamin status (n = 209) with all the assays employed. This study demonstrates the central role of 25(OH)D in regulating PTH secretion in physiological conditions.
This study was carried out to investigate early effects of parathyroidectomy (PTx) on bone matrix collagen metabolism. Eleven patients suffering from primary hyperparathyroidism were studied by ...measuring urinary excretion of hydroxyproline (OHPr) and cAMP in samples collected before PTx and, on the day of surgery, at intervals of 1-3 h for the first 10 h and then at longer intervals. In six patients nondialyzable urinary OHPr and free plasma aminoacid levels were also assayed. We found that the average period required for OHPr/Cr ratio and plasma OHPr to reach normal values was longer than the mean time required for cAMP/Cr ratio to reach normal limits. In all patients the total amount of nondialyzable OHPr decreased in the first 24 h after PTx but thereafter a daily increase in the urinary excretion of nondialyzable component was seen, so that the fractional amount of nondialyzable OHPr in the fourth postoperative day (26.8 +/- 5.2 SE) was significantly higher than that of preoperative one (6.1 +/- 1.0; p less than 0.02). Our results confirm that PTx induces a reduction in the rate of bone collagen resorption and indicate that changes of OHPr/Cr ratio and free plasma OHPr values may be considered useful indices of successful parathyroid surgery, even though they lag behind those of cAMP. The different behavior of total and nondialyzable OHPr after surgery indicates that acute deficiency of parathyroid hormone induces a positive uncoupling of the two processes of bone remodeling, thus supporting the view that the acute direct effect of the hormone on bone formation is an inhibition of this process.
The chapter deals with the QoS Management in a relief communication network able to manage the different wireless access technologies that the rescuers utilize. A QoS DiffServ-based architecture is ...proposed, which not only provides seamless QoS support over different access wireless technologies, but also exhibits a scalability property against the entry of any new access technology, since the new entry can be managed just adding a new specific QoS management module without requiring the upgrading of the ones already present in the system. A testbed for the performance evaluation of the proposed architecture has also been designed and the first results show the effectiveness of the proposal.
The Virtual Immersive Learning (VIL) test-bed intends to realize a virtual collaborative immersive environment, capable of integrating natural contexts and typical gestures, which may occur during ...traditional lectures, enhanced with advanced experimental sessions. The main aim of the paper is to describe the test-bed motivations, as well as the most significant strategies, both hardware and software, adopted for its implementation. The novelty of the authors’ approach essentially relies on its capability of remarking and emphasizing results that are the output of VICom project, and “putting the pieces together” in a well-integrated framework. These features, along with its high portability, good flexibility, and, above all, low cost, make the proposed test-bed appropriate for educational purposes, mainly concerning measurements on telecommunication systems and virtual restoration training courses at universities, as well as research centres.
Recently, the need to provide location-based services has lead to an increasing interest in accurate location sensing techniques. For indoor environments, most of proposed solutions do not generally ...provide accurate location estimates due to propagation problems. In this paper, we present NeBULa, a novel and open framework to locate a mobile user within an indoor Wireless LAN environment. It uses signal-strength information extracted from the wireless LAN interface and doesn’t require additional and costly hardware. The performances of the proposed system have been evaluated in different operative conditions to show its effectiveness.
This study was carried out in order to investigate the effects of age on the urinary excretion of total and non-dialyzable hydroxyproline (OHPr) in normal subjects. We found that total urinary OHPr ...was negatively correlated with age but, by means of partial regression analysis, no correlation was found after correction for changes in creatinine clearance; on the contrary, non-dialyzable OHPr showed a statistically significant negative correlation with age (r = -0.56) even when creatinine clearance was held constant (p less than 0.05). A highly significant direct correlation was found between total and non-dialyzable OHPr in the whole group (r = 0.54) and when only premenopausal women and men under 60 years of age were considered (r = 0.51). No correlation was found when postmenopausal women and men more than 60-year-old were taken into account. Our data appear to indicate that also the decrease in osteogenetic activity is responsible for the physiological late involutional bone loss; they also show the importance of hormonal changes in inducing an uncoupling between bone formation and resorption.
Urinary excretion of total OHPr, an index of bone resorption, was evaluated in 68 normal subjects (25 males and 43 females) aged 19-83 years. In 49 of them non-dialyzable OHPr(ndOHPr), which reflects ...bone matrix formation, was also determined. Total urinary OHPr, expressed as mg/24 h, significantly decreased with advancing age in both sexes: however by means of multiple regression analysis no correlation was found after correction of OHPr behaviour for changes in creatinine clearance. On the contrary ndOHPr was inversely correlated with age (r = -0,56, p less than 0,001) even when creatinine clearance was held constant (p less than 0,05). The findings obtained seem to show that a decrease in osteogenetic activity is also responsible for the physiological ageing bone loss.
