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Biomedical subjects

G Aicardi

Publications and source records attributed to G Aicardi.

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

Up-regulation of L- and non-L, non-N-type Ca2+ channels by basal and stimulated protein kinase C activation in insulin-secreting RINm5F cells.

We studied the effect of protein kinase C (PKC) inhibition and activation on voltage-dependent Ca2+ channels in rat insulinoma RINm5F cells. PKC down-regulation by chronic (24 h) treatment with the PKC activator phorbol 12-myristate 13-acetate (PMA) reduced by about 60% the Ba2+ currents through L- and non-L, non-N-type high-voltage-activated Ca2+ channels, indicating that PKC tonically up-regulates the two main Ca2+ channel subtypes of RINm5F cells under basal conditions. Consistently, PKC activation by acute PMA application caused only a modest increase (average 23%) of Ba2+ currents in a minority of cells (24%). L- and non-L, non-N-type channels were differentially up-regulated by either basal or stimulated PKC activation. Acute up-regulation was predominant on L-type channels and caused an I/V shift of the Ba2+ currents in the hyperpolarizing direction. Non-L, non-N-type channels were less affected by acute PMA application, possibly reflecting a more effective tonic PKC up-regulatory action. Unexpectedly, the increase of Ba2+ currents during acute PMA application was followed by a progressive current decrease, which was also observed in isolation in another 24% of the cells and could be ascribed to PKC-induced ATP depletion, rather than to a direct effect of PKC on Ca2+ channels. We also provide evidence that PKC-mediated phosphorylation is not involved in the G-protein-mediated noradrenergic modulation of Ca2+ channels in RINm5F cells.

Adenosine Triphosphate↗
PubMed1996

Fetal growth velocity: kinetic, clinical, and biological aspects.

With the aim of determining fetal growth kinetics, prenatal data were analysed which had been longitudinally collected in the framework of a perinatal growth survey. The sample comprised 238 singleton normal pregnancies, selected in Genoa and Turin (between 1987 and 1990), and repeatedly assessed by ultrasound scans (five to nine per pregnancy). Five morphometric traits were considered: BPD (biparietal diameter), OFD (occipitofrontal diameter), HC (head circumference), FDL (femur diaphysis length) and AC (abdomen circumference). Growth rate seemed to increase in the early part of the second trimester, and decrease subsequently: velocity peaks were steeper and earlier for head diameters and circumference (about 18 weeks) than for femur length (20 weeks) and abdomen circumference (22 weeks). Velocity standards were traced using a longitudinal two-stage linear model: this ensures unbiased description of the shape of the growth curve, even when growth kinetics are asynchronous, and efficient estimation of the outer centiles--the most useful for diagnostic purposes.

Abdomen↗
PubMed1994

Turner's syndrome in Italy: familial characteristics, neonatal data, standards for birth weight and for height and weight from infancy to adulthood.

In 1990, the Italian Study Group for Turner's Syndrome (ISGTS) undertook a nationwide survey, involving the retrospective collection of cross-sectional data and longitudinal growth profiles of 772 girls with Turner's syndrome born between 1950 and 1990. The study was carried out in 29 pediatric endocrinological centers. In this first report, the familial characteristics and neonatal data of Turner girls are described, compared to those of the general population, and related to postnatal somatic development. Furthermore, charts for birth weight and growth standards for height and weight from infancy to adulthood are presented (these are the first charts based on a large sample from the Mediterranean area). The main findings were: (1) incidence of Turner births increases with parental age or parity; (2) most of the neonates are small for dates; (3) girls with normal birth weight tend to be both taller and heavier than girls with low birth weight during the whole growth period; and (4) a 10-cm difference in midparental height leads to a 6.5-cm difference in adult stature.

Adolescent↗
PubMed1993

Dose-dependent effects of deflazacort and prednisone on growth and skeletal maturation.

Deflazacort (DFZ), a new glucocorticoid which has recently become available, is expected to have less negative effects on growth and skeletal maturation than conventional steroids, in children treated long term. To verify this hypothesis, a multicentre trial was organized to evaluate the effects of DFZ vs prednisone (PDN) on statural growth and skeletal maturation in a group of prepubertal children requiring glucocorticoid therapy for at least 6 months/year. The results of an analysis of 55 children (aged 3-12 years, 24 with connective tissue disease and 31 with kidney glomerular disorders) treated randomly with either DFZ (31 patients) or PDN (24 patients) and followed for a mean period of about 22 months (16 months under steroid therapy) are presented. The observation period was split up into the following phases according to dose and administration regimen: daily, high-dose therapy; alternate-day, high-dose therapy; low-dose therapy; suspension of treatment. The height, statural age, skeletal age and body weight velocities (i.e. the increase/year) were considered. In spite of large intra-individual and inter-individual variability, the results suggest that DFZ has a lower negative impact on indicators of growth. During high-dose daily administration, the height velocity tended to be lower in the PDN group and the impairment of skeletal maturity was significantly less for DFZ than for PDN. During an alternate-day regimen, height velocity was slightly higher in the PDN group and skeletal age velocity was higher in the DFZ group. It seems that steroid effects on statural growth and bone maturation occur in parallel.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Determination by Skeleton↗
PubMed1993

Excitatory amino acids as neurotransmitters of cortical and cerebellar projections to the red nucleus: an immunocytochemical study in the guinea pig.

We combined a retrograde labeling technique with peroxidase immunocytochemistry to verify whether cortical and cerebellar neurons projecting to the red nucleus (RN) contain high concentrations of glutamate and aspartate as possible neurotransmitters. Injections of a tracer, colloidal gold-labeled enzymatically inactive horseradish peroxidase conjugated to wheatgerm agglutinin, into the RN of adult guinea pigs produced retrograde labeling of layer V cortical neurons, with a large predominance in the ipsilateral hemisphere. Corticorubral neurons were located in the granular parietal cortex (Gr), agranular frontal cortex (Ag), agranular cingulate cortex (Cg), and retrobulbar cortex (Rb). Large numbers of retrogradely labeled neurons were concentrated in contralateral interpositus and dentate cerebellar nuclei. We found the majority of corticorubral neurons to be immunostained by antibodies raised in rabbits against glutamate or aspartate conjugated to invertebrate hemocyanin by glutaraldehyde, supporting the hypothesis that excitatory amino acids are neurotransmitters of corticorubral projections. With either antiserum, immunostaining was found in 58-72% of corticorubral neurons in Ag and Gr; higher percentages were observed in Rb (80-85%) and Cg (up to 96%). Cross-sectional area measurements indicated that the perikarya of corticorubral neurons were larger in Ag and Gr than in Rb and Cg; in each area, soma size values of immunopositive corticorubral neurons tended to be larger than those of immunonegative ones. In the cerebellar nuclei, virtually all retrogradely labeled neurons were immunostained by glutamate and aspartate antisera, suggesting that excitatory amino acids might also be considered as possible neurotransmitters for cerebellorubral projections.

Afferent Pathways↗
PubMed1991

Noradrenergic inhibition and voltage-dependent facilitation of omega-conotoxin-sensitive Ca channels in insulin-secreting RINm5F cells.

We found that, besides dihydropyridine-sensitive Ca channels, insulin-secreting RINm5F cells also contain a minority (15-25%) of omega-conotoxin (omega-CgTx)-sensitive channels that show a high-affinity binding to [125I] omega-CgTx (Kd 51 pM). Noradrenaline (NA, 10 microM) slows down Ca-channel activation in these cells and produces a sizeable reduction of Ca currents that is relieved by strong pre-conditioning depolarizations (facilitation). The action of NA is mimicked by intracellular application of GTP-gamma-S and is prevented by pertussis toxin (PTX) or by cell pre-incubation with omega-CgTx. This suggests specific noradrenergic inhibition of omega-CgTx-sensitive Ca channels that is modulated by membrane potentials and PTX-sensitive G-protein activation.

Animals↗
PubMed1991

Comparison of growth retarding effects induced by two different glucocorticoids in prepubertal sick children: an interim long-term analysis.

The low interference with growth expected in child for a cortisol analogue, deflazacort (DFZ), prompted us to verify if DFZ could affect growth less than prednisone (PDN). An interim analysis relative to 27 girls and 38 boys (out of 100 expected) aged 3-12 yrs, after a median period of 14 mo.s is reported. Children with connective tissues (CTD) and glomerular disorders (KD) were randomly allocated to DFZ or PDN. Anthropometric measurements and maturity ratings were performed. Mean daily doses of PDN (or DFZ equivalent), from 0.57 to 0.64 mg/kg (DFZ 0.92 to 0.94 mg/kg) to induce control and from 0.19 to 0.39 mg/kg (DFZ 0.34 to 0.36 mg/kg) to maintain disease under control were given in CTD and KD, respectively. The increase in bone age delay over time was significantly greater than for PDN (-4.0 mo/yr) than DFZ (-1.8 mo/yr) in the overall group. The increases in statural age delay and loss over time were significantly greater than for PDN (-5.9 and -5.9 mo/yr) than DFZ (-2.4 and -2.4 mo/yr), only in children with "taller" midparents. Although doses of DFZ 1.1-1.8 times those of PDN were given, growth retardation in PDN-treated children was nevertheless 2.3-2.5 times that in DFZ-ones.

Age Determination by Skeleton↗
PubMed1990

Suppression of epileptiform burst discharges in CA3 neurons of rat hippocampal slices by the organic calcium channel blocker, verapamil.

We studied the effects of the organic calcium channel blocker, verapamil, on spontaneous and bicuculine-induced epileptiform burst discharges in CA3 pyramidal cells of hippocampal slices. A transient increase of burst discharge rate was observed in most cells within 30 min after the addition of verapamil (100 microM) to the perfusing medium. Prolonged verapamil perfusions gradually reduced the rate and duration of burst discharges, then abolished them in all tested slices (over periods of 50-150 min) without blocking synaptic transmission. Responses to intracellular injections of current pulses were also gradually affected by verapamil: Action potential amplitude was decreased, action potential duration increased, frequency adaptation increased, amplitude of the fast hyperpolarization following a single action potential decreased, and amplitude and duration of the slow afterhyperpolarization markedly reduced. The amplitude of calcium spikes elicited in slices perfused with tetrodotoxin-containing medium was not affected by verapamil, but the mean velocity of depolarization near the peak of the calcium spike was decreased. Membrane resting potential and input resistance were not affected by verapamil. These results confirm that verapamil is able to suppress epileptiform activity, but suggest that this effect is rather non-specific, due to inhibition of both postsynaptic sodium and calcium conductances.

Action Potentials↗
PubMed1990

Modified Greulich-Pyle, Tanner-Whitehouse, and Roche-Wainer-Thissen (knee) methods for skeletal age assessment in a group of Italian children and adolescents.

Modified Greulich-Pyle (GP), Tanner et al. 2, radius, ulna and short bones (TW2-RUS), TW2-20-bone and Roche-Wainer-Thissen RWT (knee) skeletal age assessments were made in an Italian population sample of 128 males and 93 females aged 4.1-16.9 years. All the scales appear to be well-suited to the Italian population despite minor differences. A very high correlation was found between the assessment of knee skeletal ages by the RWT method and that of the hand-wrist by the GP and TW2 systems in the same subject without sex and age-associated variations.

Adolescent↗
PubMed1990

Multiple representations of the body and input-output relationships in the agranular and granular cortex of the chronic awake guinea pig.

The organization of somatosensory input and the input-output relationships in regions of the agranular frontal cortex (AGr) and granular parietal cortex (Gr) were examined in the chronic awake guinea pig, using the combined technique of single-unit recording and intracortical microstimulation (ICMS). AGr, which was cytoarchitectonically subdivided into medial (AGrm) and lateral (AGrl) parts, also can be characterized on a functional basis. AGrl contains the head, forelimb, and most hindlimb representations; only a small number of hindlimb neurons are confined in AGrm. Different distributions of submodalities exist in AGr and Gr: AGr receives predominantly deep input (with the exception of the vibrissa region, which receives cutaneous input), whereas neurons of Gr respond almost exclusively to cutaneous input. The cutaneous or deep receptive field (RF) of each neuron was determined by natural peripheral stimulation. All studied neurons were activated by small RFs, with the exception of lip, nose, pinna, and limb units of lateral Gr (Grl), for which the RFs were larger. Microelectrode mapping experiments revealed the existence of three spatially separate, incomplete body maps in which somatosensory and motor representations overlap. One body map, with limbs medially and head rostrolaterally, is contained in AGr. A second map, comparable to the first somatosensory cortex (SI) of other mammals, is found in Gr, with hindlimb, trunk, forelimb, and head representations in an orderly mediolateral sequence. An unresponsive zone separates the head area from the forelimb region. A third map, with the forelimb rostrally and the hindlimb caudally, lies adjacent and lateral to the SI head area. This limb representation, which is characterized by an upright and small size compared to that found in SI, can be considered to be part of the second somatosensory cortex (SII). A distinct head representation was not recognized as properly belonging to SII, but the evidence that neurons of the SI head region respond to stimulation of large RFs located in lips, nose, and pinna leads us to hypothesize that the SII face area overlaps that of SI to some extent, or, alternatively, that the two areas strictly contiguous and the limits are ambiguous, making them difficult to distinguish. The input-output relationships were based on the results of RF mapping and ICMS in the same electrode penetration. The intrinsic specific interconnections of cortical neurons whose afferent input and motor output is related to identical body regions show a considerable degree of refinement.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

'Real-motion' cells in visual area V2 of behaving macaque monkeys.

Extracellular recordings were made in area V2 of behaving macaque monkeys. Neurons were classified into three groups: non-oriented cells, oriented cells with antagonistic areas and oriented cells without antagonistic areas in their receptive field. All neurons were tested with standard visual stimulations in order to assess whether they gave different responses to the movement of a stimulus and to the movement of its retinal image alone, when the stimulus was motionless and the animal voluntarily moved its eyes. To do this, neuronal responses obtained when a moving stimulus swept a stationary receptive field (during steady fixation) and when a moving receptive field swept a stationary stimulus (during tracking eye movements), were compared. The receptive field stimulation at retinal level was physically the same in both cases, but only in the first was there actual movement of the visual stimulus. Control trials, where the monkeys performed tracking eye movements without any intentional receptive field stimulation, were also carried out. Out of a total of 263 neurons isolated in the central 10 deg representation of area V2, 101 were fully studied with the visual stimulation described above. Most of these (83/101; 82%) gave about the same response to the two situations. About 14% (14/101) gave a good response to stimulus movements during steady fixation and a very weak one to retinal image displacements of stationary stimuli during visual tracking. We have called neurons of this type "real-motion cells" (cf. Galletti et al. 1984). None of the non-oriented cells was a real-motion one, while about an equal percentage of real-motion cells was found among the oriented cells with and without antagonistic areas. Finally, we found only 4 neurons which showed behaviour opposite to that of real-motion cells, i.e. they showed a better response to displacement of the retinal image of stationary stimuli than to actual movement of stimuli. We suggest that real-motion cells might contribute to correctly evaluating movement in the visual field in spite of eye movements and that they might allow recognition of the movement of an object even if it moves across a non-patterned visual background. Present data on area V2, together with similar results observed in area V1 (Galletti et al. 1984; Battaglini et al. 1986), support the view that these two cortical areas analyse the movement in a parallel fashion along with many other characteristics of the visual stimulus.

Animals↗
PubMed1988

Growth and development in simple obesity.

It is well known that fat children tend to be taller than their peers and to present a slight acceleration of skeletal and pubertal maturation. To verify this tendency and to examine some of the points that are still controversial, auxological data were studied concerning 303 subjects (141 males and 162 females, aged 6-16 years) affected by simple obesity. Subjects were seen to be taller than average by about 1 SD from 6 to 9 years of age, becoming close to or shorter than average at later ages. Height below the 10th percentile was common in 17% of males and 8% of females, due to hereditary shortness, growth delay or late puberty. Girls had early puberty and menarche; the rate of sexual maturation was variable in boys.

Adolescent↗