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Biomedical subjects

A Rubinacci

Publications and source records attributed to A Rubinacci.

At least 37 records · Page 2Linked to original sources
PubMed1996

Comparison between urinary pyridinium cross-links and hydroxylysine glycosides in monitoring the effects of ovariectomy and 17 beta-estradiol replacement in aged rats.

This study was undertaken to assess the sensitivity of hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), galactosylhydroxylysine (GHyl) and glucosylgalactosylhydroxylysine (GGHyl) to monitor bone response to estrogen deficiency and replacement by comparing their excretory patterns in ovariectomized aged (11-14 months old) rats. The ovariectomized (OVX) rats were randomized into two groups: (1) OVX plus vehicle; (2) OVX plus 17 beta-estradiol (17-beta E, 10 micrograms/kg, s.c., 4 days/week). Treatment with 17-beta E started immediately after OVX and continued for 60 days. The collagen catabolites were measured in urine for 1 month before OVX and thereafter for 60 days. In temporal coincidence with urine collection, bone area and bone mineral density (BMD) of lumbar vertebrae, femoral diaphysis and distal metaphysis were measured by dual-energy X-ray absorptiometry. In the untreated rats, BMD of the femoral metaphysis and lumbar vertebrae decreased significantly and the urinary excretion of LP, HP, GHyl and GGHyl increased with different patterns. In the treated rats, 17-beta E replacement prevented the increment in LP excretion, partially prevented the increase in HP excretion, but had no effect on the excretion of GHyl and GGHyl. In conclusion pyridinolines and glycosides have different sensitivities to the bone response to OVX. Glycoside excretion after OVX also reflects metabolic processes not strictly related to bone loss and, in contrast with LP, is not sensitive to estrogen replacement.

Absorptiometry, Photon↗
PubMed1996

Osteocalcin production in vivo and in vitro after 1,25-dihydroxycholecalciferol stimulation comparison of different assays.

The study was designed to assess the sensitivity of three commercial assays (which differ in methodology, standard and antibodies) for osteocalcin, used for detecting changes in osteocalcin secretion induced by calcitriol (1,25-dihydroxycholecalciferol) in vivo and in vitro. Osteocalcin levels were determined in serum samples of 10 osteoporotic women after short term calcitriol treatment, and in the culture medium of human osteoblast-like cells (n = 22) after 48 h calcitriol exposure. All assays displayed similar sensitivity in detecting osteocalcin production in vivo after a 1 microgram daily dose of calcitriol. A novel IRMA (CIS), claimed to detect intact osteocalcin, showed higher osteocalcin values than the other assays, and in vitro showed the best sensitivity; it provides an appropriate index of the osteocalcin synthetic activity of cultured human osteoblasts.

Aged↗
PubMed1995

Time-relationship between bone growth and increment of bone mineral content in growing rats.

The aim of the study was to describe the time-relationship between the growth rate of the rat tibia and the increase rate of its mineral content. Appositional and endochondral bone growth rates were derived from sequential X-rays measurements of tibial widening and lengthening, respectively; the increase rate of bone mineral content was derived from sequential photon absorptiometry measurements of the proximal tibio-fibular site. The time-relationship of appositional growth rate and endochondral growth rate versus bone mineral content increase rate was mathematically described. The results allow a better understanding of the time-course of two distinct features of bone growth: increase in size and increase in mineral content.

Absorptiometry, Photon↗
PubMed1994

Analgesic effect of intranasal and intramuscular salmon calcitonin in post-menopausal osteoporosis: a double-blind, double-placebo study.

Different types of calcitonin (porcine, human, salmon) are used in the management of bone diseases characterized by a high bone turnover, such as post-menopausal osteoporosis and Paget's disease; recently, salmon calcitonin has become clinically available as an intranasal (i.n.) spray. An analgesic effect has also been described for calcitonins, both in experimental animals and humans, but only a few studies in humans were placebo controlled. The aim of this study was to compare the analgesic efficacy of i.n. and intramuscular (i.m.) salmon calcitonin (sCT) and of placebo in women affected by painful post-menopausal osteoporosis, in a double-blind, double-placebo trial. Twenty-eight women were randomly allocated to one of the following treatments: 1) i.n. sCT 200 U/day plus i.m. placebo; 2) i.n. placebo plus i.m. sCT 100 U/day; and 3) i.n. and i.m. placebo. Each treatment lasted four weeks, and the pain score was evaluated weekly by means of a visual analogic scale (VAS). Twenty-four women completed the trial; with i.n. sCT, the pain score decreased significantly by the second week of treatment (p < 0.05); with i.m. sCT and with placebo, the pain score decreased significantly only by the fourth week (p < 0.05), so that the final pain scores obtained with the three treatments were not different. We conclude that i.n. sCT was probably more rapid, but not more effective than i.m. sCT or placebo in decreasing pain in post-menopausal osteoporosis.

Administration, Intranasal↗
PubMed1992

A new mathematical model to study bone turnover in growing rats.

A new mathematical model for the study of bone turnover in growing rats was developed. The model predicts a linear relationship between bone mineral content (BMC) and biochemical markers (BMK) of bone turnover assuming that rats are growing, bone turnover is profoundly affected by skeletal maturation, and resorption and formation are physiologically balanced. The model validation was performed by measuring galactosyl-hydroxylysine (GHYL) and hydroxyproline (HYP) in urines. This mathematical evidence supports our proposed use of the specific bone resorption marker GHYL to predict bone mineral content. Further studies on bone turnover will be possible by the application of the same approach.

Absorptiometry, Photon↗
PubMed1992

Thyroid hormones and active calcium transport of inside-out red cell membrane vesicles.

Thyroid hormones may influence the active transport of Ca2+ across the cell membrane. To test the physiologic relevance of this mechanism, we used inside-out human red cell membrane vesicles as a model of the cell membrane Ca2+ pump. We monitored by spectrophotometric methods the kinetics of the uptake of Ca2+ in the presence of 10(-5)-10(-10) M thyroid hormones or their analogues. Vesicles freed of calmodulin and protein inhibitor(s) of the Ca2+ pump were also obtained. The results are as follows: (1) Thyroxine inhibits the active Ca2+ uptake; (2) this effect antagonizes that of soluble calmodulin; and (3) triiodothyronine and other analogues of the thyroid hormones are less active than thyroxine. We conclude that the thyroid hormones may influence cell Ca2+ homeostasis by direct action on the Ca2+ pump.

Adult↗
PubMed1992

[Nutrients, anthropometric characteristics and osteoporosis in women in the recent and late postmenopausal period].

Bone mineral content (BMC) at two different radial sites (mid-diaphysis and ultra-distal epiphysis), anthropometric measurements (Body Mass Index, Lipidic Area, and Muscular Area) and nutrients intake were measured in two populations of women selected on the basis of early (< 9 years) or remote (> 15 years) menopause. The results show the presence of positive relationships between BMC, and protein and lipid intakes in the population of women in early menopause; in the other population no relationships were found. Glucid, fibre and calcium intakes were not related to the BMC of both populations. The positive relationships between BMC, and protein and lipid intakes in the population of women in early menopause is likely mediated by anthropometric characteristics as Body Mass Index and Muscular Area.

Adult↗
PubMed1992

[Influence of nutrition, age and vitamin D status on fasting urinary excretion of calcium in postmenopausal women].

The purpose of the present study was to evaluate the influence of nutrition, age, and Vitamin D status on fasting urinary calcium (Ca) as a function of creatinine excretion (Ca/Cr) and of glomerular filtration rate (Ca/GFR) in postmenopausal women. Fasting urinary calcium, urinary Cr and GFR were measured in 18 women aged 54 to 91 years before and after six days of a calcium (400 mg/die) and sodium (100 mEq/die) restricted diet with a controlled content of proteins, lipids and glucides. Aged (over 64 y.) women having an adequate vitamin D status showed fasting urinary Ca/Cr and Ca/GFR after the controlled diet significantly lower than those showed before. It is concluded that fasting Ca/Cr and Ca/GFR may be nutrition-dependent. A revision of the significance of the fasting urinary Ca excretion is consequently suggested.

Age Factors↗
PubMed1992

[Dual-energy X-ray absorptiometry of the vertebrae: determining which vertebrae should be scanned].

This study was aimed at verifying whether bone mineral density (BMD) and its loss with aging are different in the lumbar vertebrae and whether the region of interest--which is usually limited to the L2-L4 segment--may be extended to L1-L4. BMD was measured by means of dual-energy X-ray absorptiometry (Hologic QDR 1000) in 74 women, aged 37 to 78 years, not affected with any disease or subjected to any treatment known to interfere with bone metabolism. The relationship between age and BMD was expressed by the following equations for L1, L2, L3: BMD-L1 = 1181.68-7.85 x age, BDM-L2 = 1251.57-7.70 x age, BMD-L3 = 1231.66-6.57 x age, as shown by linear regression analysis. The behavior of the bone density of L4 with age appeared to be different and could not be described by linear regression curves and was therefore not comparable with that of the other vertebrae. BMD was different in the four lumbar vertebrae as shown by: a) the diversity of the intercept of the regression lines describing age-bone density relationships (F = 7.7, p < 0.001); b) the bone density of L1 being lower than the mean bone density of the L2-L4 region (p < 0.005); c) the bone density of L4 being higher than the mean bone density of the L1-L3 region (p < 0.001). In order to evaluate the effect of senile degenerative changes of the vertebrae on the relevant bone density, two groups of women were considered, according to age--i.e., pre- or iuxtamenopausal and late postmenopausal. It appeared that the BMD of L1 was always more correlated to the bone density of L2 and L3 than the BMD of L4. Our results suggest that L1 is homogeneous to the L2-L3 region, relative to both bone density and its loss with aging. Therefore, L1 should be included in the region of interest during the examination. Even though the bone mineral content of L4 and its loss with aging seem to be different, our results do not allow the exclusion of L4 from the scanned area.

Absorptiometry, Photon↗
PubMed1990

Human red cell age, oxygen affinity and oxygen transport.

The [2,3-DPG]/[Hb] ratio and the P50 were found to be lower in the 10% denser (old) than in the 10% lighter (young) red blood cell (RBC) fractions (0.57 +/- 0.13 vs 0.96 +/- 0.13 and 23.02 +/- 0.85 vs 27.47 +/- 1.05 Torr, respectively, mean +/- SD, P less than 0.0005 for both, n = 6). The RBC aging processes appear thus to affect the RBC oxygen affinity. However, the [2,3-DPG] changes do not fully explain the drop of not fully explain the drop of P50 as measured at constant [H+], [CO2] and [HbCO]. It is therefore postulated that an additional factor is involved in the regulation of the oxygen affinity in the ageing RBC. The RBC density in 59 normal individuals matched for age (infants, adult, and aged) and for sex was found to be younger in adult females than in all other groups (P less than 0.0005), including an age-matched group of pregnant women. Correspondingly, the [2,3-DPG]/[Hb] ratio and the P50 are higher in adult females than in adult males (0.92 +/- 0.10 vs 0.82 +/- 0.09, P less than 0.009, and 29.03 +/- 1.07 vs 27.72 +/- 0.82 Torr, P less than 0.002, respectively). These data are evaluated in terms of the efficiency of the oxygen transport calculating the circulatory load required to transport a given amount of oxygen to the tissues. The results indicate that the lower oxygen affinity (due to the younger RBC population) in adult females partially compensates for their lower [Hb].

Adult↗
PubMed1990

Red cell aging and active calcium transport.

The authors have investigated the relationships between the active calcium transport across the human red blood cell (RBC) membrane and the RBC aging processes in vivo and in vitro. For the study of this biological system, the authors have determined the active calcium uptake by inside-out membrane vesicles obtained from selected RBC populations. This model provided an optimal way to assess the biochemical and functional responses of the human cell to the oxidative stimulus triggered by the cellular aging processes. The activity of the calcium pump is indeed strictly correlated to the oxidative damage suffered by the RBC, being higher in the aged RBC. It appears that the main controller of the active calcium transport is the age-dependent protein inhibitor of the calcium pump.

Adult↗
PubMed1989

The effect of in vitro and in vivo cellular aging on the active calcium transport in human inside-out red cell membrane vesicles.

Modelling of the in vivo and in vitro aging processes in the human red cell has stressed the following features of the active calcium uptake by inside-out vesicles: 1) it is higher in the outdated, in vitro aged, than in the fresh red cell (p less than 0.0005), and in the densest, in vivo aged fraction than in the lightest, young fraction (p = 0.08); 2) it increases following stimulation by excess calmodulin to values that are not significantly different; 3) it decreases to the same value in the absence of endogenous calmodulin and inhibitor, with and without exogenous calmodulin; 4) it is the target of a non-competitive inhibition, that is stronger in the fresh than in the outdated red cell. We conclude that the aging process does not involve neither membrane Ca-ATPase nor calmodulin, but rather the interaction of the calcium pump with the inhibitor of Ca-ATPase.

Biological Transport, Active↗
PubMed1989

The bioenergetics of mitochondria after cryopreservation.

The functional characteristics of rat liver mitochondria after cryopreservation with and without the addition of the cryoprotectant dimethyl sulfoxide (Me2SO) were evaluated. As criteria of functional integrity, polarographic measurements of substrate-linked oxygen consumption and luminescent assay of adenosine triphosphate (ATP) synthesis were considered before and after cryopreservation. The results demonstrated that mitochondrial damage after freezing was indicated by the polarographic studies but was not evident when ATP synthesis was considered. Me2SO present during cryopreservation was partially protective for mitochondrial substrate-linked oxygen consumption; however, simple exposure to and dilution from Me2SO effected some changes in mitochondrial function.

Adenosine Triphosphate↗
PubMed1989

Immunocytochemical distribution of extracellular matrix receptors in human osteoclasts: a beta 3 integrin is colocalized with vinculin and talin in the podosomes of osteoclastoma giant cells.

Human osteoclasts (OCLs) obtained from cell suspensions of surgically excised giant cell bone tumors (osteoclastomas) were attached to glass coverslips and analyzed by immunofluorescence with antibodies to integrins and cytoskeletal proteins. It was found that in OCLs (i) podosomes, identified by their F-actin core and by interference reflection microscopy, were predominantly found in a peripheral belt as described in avian OCLs; (ii) each F-actin core was surrounded by a ring of vinculin and talin; (iii) beta 1 integrin was diffuse in the ventral membrane; (iv) beta 3 integrin was distributed in intensely fluorescent rings surrounding F-actin cores; (v) beta 2 integrin was absent; (vi) beta 4 integrin was absent. The macrophages detected in the same coverslips displayed podosomes containing beta 2 but not beta 3, fibroblasts showed adhesion plaques positive for beta 1 and beta 3 but not for beta 2, and platelets were intensely positive for beta 3. These results indicate that OCLs produce an integrin complex that is absent in the monocyte-macrophage lineage.

Actins↗
PubMed1989

[Mineral bone content in full-term infants. Effect of anthropometric characteristics].

The clinical importance of the measurement of bone mineral content (BMC) in fullterm infants by photon absorptiometry relies on a comparatively narrow normative range that is necessary requisite to interpret the data from a single child. In the attempt to reduce the artifactual scattering of data, it was undertaken a normative study to control all variables that might affect BMC at birth. Thus, growth parameters and birth season (as an index of maternal vit. D status) were related to BMC, Bone Width (BW) and the considered growth parameters did not show any significant difference related to sex and birth season. Thus, all data were analyzed together. It appears that BMC at birth in fullterm infants averaged 92.2 +/- 14.6 mg/cm. BMC did not correlate with skeletal length, crown length and gestational age in the considered range. Conversely, significant correlation were found between BMC and BW and between BMC and body weight. We conclude that: a) birth season and sex do not affect bone mineralization in fullterm infants, b) any comparison among BMC should be established within populations homogeneous for weight and BW.

Anthropometry↗
PubMed1989

[The measurement of ultradistal radial bone minerals in women in the menopause].

An anthropometric, radiomorphometric and absorptiometric study was carried out to check whether or not reliable information about the mineral content of trabecular bone could be acquired from the ultradistal epiphysis of the human radius. The results indicate that a radius scan 1.2 to 1.6 cm proximal to the ulnar styloid tip gives reproducible information as to the mineral content of a bone which is mainly trabecular in nature. In the ultradistal radial region the bone mineral analyzer (Norland 2780) was always able to automatically find bone edges. The measurement error was 4%, and BMC values were not significantly different in the various subjects; BMC values were positively correlated with body mass and muscular area in postmenopausal women. Conversely, in no subject a direct correlation was found between BMC and BW values at sequential scan sites; BMC/BW ratios were more than 10% variable, and the differences were statistically significant (p less than 0.01). Finally, the comparison of age-related changes in the BMC of ultradistal and mediodiaphyseal radii demonstrated that the former expresses the specific metabolic reactivity of the trabecular bone.

Absorptiometry, Photon↗
PubMed1988

Changes in bioelectric potentials on bone associated with direct current stimulation of osteogenesis.

This study was designed to determine whether changes occur in the bioelectric potentials on bone during and after bone stimulation with a 20-microA direct current (DC) and whether the variations in bioelectric potentials are related to the variations in bone formation. The bioelectric potentials were recorded at different times on the rabbit distal tibial surface, during (current-on state) and after (current-off state) DC stimulation with a cathode implanted within the medullary canal. The new bone formed at the end of the experiment was quantitated and related to the bioelectric potentials recorded at current-on and current-off states, respectively. Direct current stimulation resulted in electronegative potential spike centered on the cathode tip while current was applied. After electrical stimulation was turned off, the residual potentials at the end of the experiment did not significantly differ from the initial values. Conversely, the time sequence of the changes was significantly different from the control to the experimental group. The variations in the induced potentials at current-on state were significantly related to the variations in bone formation. This study suggests the existence of a relationship among bioelectric potentials, DC stimulation, and osteogenesis.

Animals↗