Biomedical subjects

Giorgio Aicardi

Publications and source records attributed to Giorgio Aicardi.

7 recordsLinked to original sources

PubMed2006

Hippocampal neurons recycle BDNF for activity-dependent secretion and LTP maintenance.

Regulation of brain-derived neurotrophic factor (BDNF) secretion plays a critical role in long-term potentiation (LTP). It is generally thought that the supply for this secretion is newly synthesized BDNF targeted to the synapse. Here we provide evidence that hippocampal neurons additionally recycle BDNF for activity-dependent secretion. Exogenously applied BDNF is internalized by cultured neurons and rapidly becomes available for activity-dependent secretion, which is controlled by the same mechanisms that regulate the secretion of newly synthesized BDNF. Moreover, BDNF recycling replaced the new synthesis pathway in mediating the maintenance of LTP in hippocampal slices: the late phase LTP, which is abolished by protein synthesis inhibition, was rescued in slices preincubated with BDNF. Thus, endocytosed BDNF is fed back to the activity-dependent releasable pool required for LTP maintenance.

Animals↗

PubMed2005

Context is a trigger for relapse to alcohol.

The environment in which alcohol consumption occurs may trigger later relapse in alcohol abusers. In this study, we tested whether an alcohol-associated environment would induce alcohol-seeking behavior. Male rats were trained to lever press for oral alcohol reinforcement in a distinctive context. Responding was then extinguished in a context with different olfactory, visual and tactile properties. Placement of the rats back into the original context in which they self-administered alcohol induced, in the absence of alcohol availability, a significant increase in lever press responding on the alcohol lever as compared to extinction levels of responding. The ability of the alcohol context to support alcohol-seeking behavior was maintained over 3 weeks, with no significant diminution. A second group of rats was trained to lever press for sucrose reinforcement; this group also demonstrated context-dependent reinstatement, although the degree of reinstatement decreased over repeated tests, returning to extinction values after 3 weeks. These findings indicate that contextual conditioning has a long-term impact on ethanol-seeking behavior after ethanol withdrawal. This animal model may be useful to study the neural mechanisms underlying relapse induced by ethanol-associated contexts in humans.

Alcohol Drinking↗

PubMed2005

L- and T-type voltage-gated Ca2+ channels in human granulosa cells: functional characterization and cholinergic regulation.

Using the whole-cell configuration of the patch-clamp technique, we have characterized two types of ionic currents through voltage-dependent Ca2+ channels in human granulosa cells. One is long-lasting, activates at approximately -20 mV, reaches the peak at approximately +20 mV, has an inactivation time constant of 132.5 +/- 5.6 msec at 20 mV, and is sensitive to dihydropyridines. The other is transient, activates at approximately -40 mV, peaks at approximately -10 mV, has an inactivation time constant of 38.8 +/- 1.8 msec at -10 mV, displays a voltage-dependent inactivation, and is sensitive to 100 microm Ni2+, but not to dihydropyridines. Biophysical and pharmacological properties of these currents indicate that they are gated through L- and T-type calcium channels, respectively. The cholinergic receptor agonist carbachol (50 microm) reduces the amplitude of the currents through both L-type (-34.7 +/- 6.4%; n = 10) and T-type (-52.6 +/- 7.4%; n = 8) channels, suggesting a possible role of these channels in the cholinergic regulation of human ovarian functions.

Calcium↗

PubMed2005

Relationship between body mass index and asthma characteristics in a group of Italian children and adolescents.

The prevalence of asthma and obesity, two often associated conditions, is influenced not only by age and gender but also by lifestyle factors. This study aimed to determine whether, in a Mediterranean northern Italian region, Liguria, an increased prevalence of obesity could be detected in asthmatic children and adolescents and to evaluate the possible relationship between body mass index (BMI) and the characteristics and/or severity of asthma. BMI was determined in 554 asthmatic subjects (2.2-16.1 years) and 625 age-matched controls; BMI was expressed as a continuous variable in standard deviation score (SDS) units, determined as difference between the individual observed value and the reference mean for age and sex, divided by the corresponding standard deviation (BMI-SDS). Overweight/obesity was set at BMI-SDS of 2 or more. BMI-SDS was significantly higher in controls than in asthmatics (p = 0.04); however, the proportion of overweight/obesity subjects (BMI-SDS > or = 2) was similar in controls and in asthmatic patients (p = 0.08). Evaluation of the asthmatic group revealed that BMI-SDS was independent of gender (p = 0.57), atopic sensitization (p = 0.69), and comorbidity with other allergic symptoms (p = 0.60). By contrast, BMI-SDS was lower in preschool-age children than in school-age children and adolescents (p < 0.0001), in subjects with a high rate of acute respiratory tract infections (p = 0.04), and in those not treated with inhaled corticosteroids (IGCs) (p = 0.02). Although an increase in the prevalence of overweight/obesity was not detected in asthmatic children and adolescents, the results reported here suggest a preventive surveillance of calorie intake and a promotion of physical activity in children requiring long-term treatment with inhaled glucocorticosteroids.

Adolescent↗

PubMed2004

Differences in size at birth are determined by differences in growth velocity during early prenatal life.

Physiologic interindividual differences in neonatal size are traditionally thought of as determined by differences in fetal growth occurring only in the second half of pregnancy. Whether possible differences in early intrauterine growth velocity are the effect of random growth fluctuations or may affect size at birth is still debated. This article aims at evaluating to what extent differences in neonatal size are accounted for by differences in fetal growth velocity. We analyzed the fetal growth of 130 healthy singletons for whom head (HC) and abdomen (AC) circumferences and femur diaphysis length (FDL) longitudinal profiles were available, together with the measures of weight (BW), length (BL), and head circumference (BHC) at birth. Individual profiles were fitted with ad-hoc models. Neonatal traits were transformed into standard deviation scores (SDS). Neonates in the upper third of BW-SDS distribution (3618+/-43 g, mean+/-SEM) had, at 22 wk of gestational age, AC growth velocity higher by 0.55+/-0.10 mm/wk than those in the lower third (2902+/-36 g). Neonates in the upper third of BL-SDS distribution (51.7+/-0.21 cm) had, at 20 wk, FDL growth velocity higher by 0.11+/-0.05 mm/wk than those in the lower third (48.2+/-0.18 cm). Neonates in the upper third of BHC-SDS distribution (35.7+/-0.13 cm) had, at 18 wk, HC growth velocity higher by 0.57+/-0.20 mm/wk than those in the lower third (33.3+/-0.11 cm). The differences in growth velocity remain constant throughout the second and third trimester for AC, and tend to vanish in the third trimester for HC and FDL. The differences in fetal growth velocity, which in our study were observed as early as mo 4, suggest that the genetic component plays an important role in fetal growth and is precociously expressed.

Birth Weight↗

PubMed2004

Induction of long-term potentiation and depression is reflected by corresponding changes in secretion of endogenous brain-derived neurotrophic factor.

Neurotrophins play an important role in modulating activity-dependent neuronal plasticity. In particular, threshold levels of brain-derived neurotrophic factor (BDNF) are required to induce long-term potentiation (LTP) in acute hippocampal slices. Conversely, the administration of exogenous BDNF prevents the induction of long-term depression (LTD) in the visual cortex. A long-standing missing link in the analysis of this modulatory role of BDNF was the determination of the time-course of endogenous BDNF secretion in the same organotypic preparation in which LTP and LTD are elicited. Here, we fulfilled this requirement in slices of perirhinal cortex. Classical theta-burst stimulation patterns evoking LTP lasting >180 min elicited a large increase in BDNF secretion that persisted 5-12 min beyond the stimulation period. Weaker theta-burst stimulation patterns leading only to the initial phase of LTP ( approximately 35 min) were accompanied by a smaller increase in BDNF secretion lasting <1 min. Sequestration of BDNF by TrkB-IgG receptor bodies prevented LTP. Low-frequency stimulations leading to LTD were accompanied by reductions in BDNF secretion that never lasted beyond the duration of the stimulation.

Animals↗

PubMed2000

Assessment of skeletal maturity of the hand-wrist and knee: A comparison among methods.

This study evaluated the influence of height growth and nutritional status on skeletal maturation of the knee and hand-wrist. Radiographs of 589 subjects (250 girls and 339 boys) from 2 to 15 years were rated according to Greulich-Pyle, TW-20 bone and TW-RUS, RWT knee, and FELS hand-wrist methods and a method combining FELS and RWT indicators. The subjects were referred to the Genoa University Paediatric Department from 1980 to 1987 for short stature, simple obesity, or acute diseases. Bone age was closer to chronological age using the RWT knee method rather than the hand-wrist methods, while bone age assessed at the hand-wrist was closely related to height and BMI. When skeletal maturation was delayed, Greulich-Pyle, TW-20-bone, TW-RUS, and FELS bone ages tended to be lower than RWT knee estimates. Conversely, if maturation was advanced the hand-wrist estimates tended to be higher than RWT knee bone ages. The combined estimates are close to FELS bone age values. These findings show true intraindividual variability of skeletal maturity at the hand-wrist and knee. A certain "laziness" in knee maturation seems to be confirmed. Am. J. Hum. Biol. 12:610-615, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗