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G Traina

Publications and source records attributed to G Traina.

At least 19 recordsLinked to original sources
PubMed2006

Acetyl-L-carnitine affects nonassociative learning processes in the leech Hirudo medicinalis.

Acetyl-L-carnitine is a natural molecule widely distributed in vertebrate and invertebrate nervous system. It is known to have significant effects on neuronal activity playing a role as neuroprotective and anti-nociceptive agent, as well as neuromodulatory factor. About its capability of affecting learning processes the available data are controversial. In the present study, we utilized the simplified model system of the leech Hirudo medicinalis to analyze the effects of acetyl-L-carnitine, assessing whether and how it might affect elementary forms of nonassociative learning processes. In leeches with the head ganglion disconnected from the first segmental ganglion, repetitive application of weak electrical shocks onto the caudal portion of the body wall induces habituation of swim induction whereas brush strokes on the dorsal skin produces sensitization or dishabituation when the nociceptive stimulus is delivered on previously habituated animals. Herein, the effects of different concentrations of acetyl-L-carnitine (2 mM - 0.05 mM) have been tested at different times on both sensitization and dishabituation. The results show that a single treatment of acetyl-L-carnitine blocked the onset of sensitization in a dose- and time-dependent manner. In fact, the most effective concentration able to block this process was 2 mM, which induced its major effects 11 days after the treatment, whereas 0.05 mM was unable to affect the sensitization process at all considered time points. On the contrary, acetyl-L-carnitine did not completely abolish dishabituation at the tested concentrations and at every time point. Finally, acetyl-L-carnitine also impaired the habituation of swim induction, but only 11 days after treatment.

Acetylcarnitine↗
PubMed2001

Nonassociative learning in the leech Hirudo medicinalis.

In the present study we examined nonassociative learning of the induction of swimming which was evoked by weak electrical stimulation in the leech Hirudo medicinalis. The behavioural response to stimuli applied repeatedly to the body wall at an inter-trial interval (ITI) of 1 min decreased, eventually ceased, and then recovered spontaneously. More rapid reduction of the behavioural response occurred in repeated training sessions. This decrement of response conformed to the operational definition of habituation. Moreover, a noxious stimulus (i.e. brushing on the skin) facilitated the decremented response (dishabituation). In addition, we compared response decrement in naive animals with decrement in dishabituated and in sensitized animals. The analysis of the best fitting functions of the habituation, the habituation of dishabituation and the habituation of sensitization revealed interesting differences in these processes.

Animals↗
PubMed2001

Assembly and clustering of acetylcholine receptors containing GFP-tagged epsilon or gamma subunits: selective targeting to the neuromuscular junction in vivo.

Acetylcholine receptor (AChR) gamma and epsilon subunits were tagged by green fluorescent protein (GFP) to analyse assembly and targeting in live muscle fibers at the neuromuscular junction. N- or C-terminal fusion polypeptides showed no fluorescence upon transfection of HEK cells. When GFP was inserted into the cytoplasmic loop connecting putative transmembrane regions M3 and M4, the gamma/GFP and epsilon/GFP subunits were fluorescent and formed together with the alpha, beta, and delta subunits GFP-tagged AChR complexes that were integrated into the plasma membrane. As the AChR were also clustered by rapsyn, the results indicate that the cytoplasmatic domains of the gamma and epsilon subunits may not be required for assembly and rapsyn-dependent clustering. The gamma/GFP and epsilon/GFP subunit-containing receptors were expressed in X. laevis oocytes and have affinities for acetylcholine similar to that of the wild-type receptors. Direct gene transfer into single muscle fibers reveals that gamma/GFP or epsilon/GFP polypeptides are expressed at the site of injection and are transported within the endoplasmatic reticulum. When reaching subsynaptic regions, both gamma/GFP or epsilon/GFP subunits compete with endogenous epsilon subunits to assemble GFP-tagged receptors, which are selectively targeted to the postsynaptic membrane.

Animals↗
PubMed2000

Neurotoxic effects of caulerpenyne.

1. In this paper the authors tested the effect of caulerpenyne (CYN), a sesquiterpene synthesized by the green alga Caulerpa taxifolia onto the central nervous system of the leech Hirudo medicinalis. Investigations have been performed with three different approaches: neuroethological, electrophysiological and neurochemical techniques. 2. CYN application mimics the effect of a nociceptive stimulation (brushing), eliciting a clear-cut potentiation of the animal swim response to the test stimulus (non associative learning process such as sensitization). This effect is similar to that one induced by the endogenous neurotransmitter serotonin (5HT). 3. CYN strongly reduces the after-hyperpolarization (AHP) recorded from T sensory neurons. This effect overlaps that one produced by 5HT, but it is not affected by the serotonergic antagonist methysergide. 4. The decrease of AHP amplitude due to CYN application is observed also in presence of apamin, a blocking agent of Ca++-dependent K+ channels, suggesting that CYN is acting through the inhibition of the Na+/K+ electrogenic pump. 5. The depression of the AHP driven by CYN is not prevented by application of MDL 12330A, an adenylate cyclase inhibitor. On the other hand MDL 12330A counteracts the reduction of AHP due to 5HT application. 6. Incubation of the leech central nervous system with CYN induces the phosphorylation of proteins of 29, 50, 66 and 100 kDa. This pattern of phosphorylation is similar to that one elicited by 5HT treatment. 7. The data demonstrate that CYN exerts remarkable effects on leech neurons by acting onto specific molecular targets such as the Na+/K+ ATPase. This effect may influence important neural integrative functions and may explain the sensitizing action produced by the toxin on swim induction. Finally, caulerpenyne does not act through the pathways involved in the 5HT action, and its effect is not mediated by the second messenger cyclic AMP. The mechanism of action of CYN are still under investigations.

Animals↗
PubMed1999

Mechanisms mediating somatostatin-induced reduction of cytosolic free calcium in PC12 cells.

In PC12 cells, somatostatin (SRIF) decreases the Ca2+ influx in response to high K+ through the inhibition of voltage-dependent Ca2+ channels. In the present study, we measured the intracellular Ca2+ concentration ( [Ca2+]i) following the application of SRIF-14 or its analogues which bind to different SRIF subtype (sst) receptors. Their application differentially reduces [Ca2+]i (octreotide > SRIF-14 > CGP23996 > BIM23056) in a dose-dependent manner. Pretreatment with a SRIF antagonist prevents the SRIF-induced inhibition of [Ca2+]i. These results suggest the involvement of specific membrane receptors and are in line with recent findings indicating the presence of receptor mRNAs on PC12 cells. Our results also exclude the possibility that SRIF interacts with opioid receptors and suggest that the SRIF-induced inhibition of [Ca2+]i is mediated by mechanisms involving PTX-sensitive G-proteins and PK-dependent pathways.

Animals↗
PubMed1998

Somatostatin enhances neurite outgrowth in PC12 cells.

The rat pheochromocytoma cell line PC12 forms neurites in response to nerve growth factor (NGF), and it was also reported to extend processes in the presence of somatostatin (somatotropin release-inhibiting factor, SRIF), a neuroactive peptide that seems to act as a morphogenetic factor in the developing nervous system. In the present study, we re-evaluated the effects of SRIF on PC12 cell differentiation. Our results indicate that SRIF alone is ineffective in promoting neurite outgrowth. Instead, SRIF or its analogue, octreotide (a SRIF agonist on the receptor subtypes 2, 3 and 5), potentiates neurite extension induced by NGF. These results suggest that SRIF enhances neurite formation in PC12 cells without directly promoting neurite outgrowth. SRIF potentiation of NGF-induced neurite outgrowth persists at least in part in the presence of pertussis toxin (PTX), suggesting the involvement of PTX-insensitive G-proteins. In addition, protein kinase-dependent pathways are likely to mediate SRIF effects on NGF-induced differentiation.

Animals↗
PubMed1998

Expression and coupling of somatostatin receptors in rat adrenal (PC12) and pituitary (GC) cell lines.

Somatostatin (somatotropin release-inhibiting factor, SRIF) interacts with G-protein coupled receptors (sst) designated sst1 through sst5. In PC12 and GC cells, SRIF binding sites were identified and mRNA receptor expression was evaluated. SRIF binding sites were expressed at a much lower density in PC12 (Kd = 21.2 +/- 3.9 nM; Bmax = 31 +/- 8 fmol/mg protein) than in GC cells (Kd = 6.4 +/- 1.6 nM; Bmax = 643 +/- 29 fmol/mg protein). sst3 receptor mRNA (81% of the total) was mainly expressed in PC12 cells, while sst1/2 receptor mRNAs were mostly expressed in GC cells (64 and 29%, respectively). In PC12 cells, adenylyl cyclase (AC) activity was unaffected by SRIF-14 (binding all SRIF receptors), octreotide (specific for sst2/3/5 receptors), BIM 23056 (binding sst3/5 receptors) or CH275 (specific for sst1 receptors), 1 microM each. In GC cells, SRIF-14 or octreotide, but not the two other peptides, significantly inhibited AC activity.

Adenylyl Cyclases↗
PubMed1997

[Clinical heterogeneity of Kawasaki disease].

Kawasaki's disease is a systemic vasculitis typical of infancy that affects children under five years old. Given that it is important to make an early diagnosis and to start prompt treatment of this disease owing to possible cardiac complications, even in the long term, the authors felt it important to report a number of cases referred to their attention in order to underline the polymorphism of onset. The symptoms that are considered to be typical of the disease, namely fever, laterocervical adenopathy, alterations of the extremities, polymorphous rash, orolabial modifications, conjunctival hyperemia, can often be masked by the symptoms provoked by the possible involvement of all the organs and apparatuses.

Child↗
PubMed1996

Effects of somatostatin on intracellular calcium concentration in PC12 cells.

Somatostatin (SS) is a neuropeptide that is distributed in various regions of the CNS, where it may act as a neurotransmitter or neuromodulator. SS produces multiple effects in the CNS through interactions with membrane receptors. In particular, SS inhibits various secretory responses in different cell types. In the present study, we have investigated the effects of exogenous application of SS on the intracellular free Ca2+ concentration ([Ca2+]i) in PC12 cells, a rat pheochromocytoma cell line. SS did reduce the magnitude of the secondary, maintained Ca2+ influx brought about by K+ depolarization. Similar effects were obtained with the application of SS analogues, such as D-Trp8-SS, D-Trp8-D-Cys14-SS, CGP-23996, and SMS-201995. In addition, treatment with cyclo-SS, a SS antagonist, did not alter [Ca2+]i. Experiments with selective blockers of different voltage-dependent Ca2+ channels, such as methoxyverapamil (D600) and omega-conotoxin GVIA, demonstrated that the effects of SS on [Ca2+]i were mediated by voltage-dependent Ca2+ channels of the L type. Control experiments with a membrane potential indicator, i.e., the fluorescent dye bisoxonol, excluded that SS influenced the level of the membrane potential. SS effects on PC12 cells suggest the possibility that this neuropeptide plays a role in the modulation of cell functional activity by altering Ca2+ influx.

Animals↗
PubMed1996

Intracellular free calcium and its modulation.

Over the past six years, Ca2+ channels have continued to receive much attention, partly as a result of their biological importance as excitation-response transducers, and partly as a result of exciting developments in enlightening their molecular properties and cellular functions. Neurotransmitter release, neurosecretion, neuronal excitation, survival of neurons, and many other neuronal functions are controlled by the cellular [Ca2+]. In turn the rise in [Ca2+]i modulates specific cellular functions. The enhancement of [Ca2+]i is modulated by various factors, peptidergic and not.

Animals↗
PubMed1992

Inactivation of the slow calcium current in twitch skeletal muscle fibres of the frog.

1. We investigated inactivation of the slow calcium current (ICa) at very positive potentials (over 30-40 mV) and recovery from inactivation in cut twitch skeletal muscle fibres of the frog, using the double-vaseline-gap technique. External solutions were buffered against changes in [Ca2+] (Ca(2+)-buffered) with malate. Internal solutions were Ca(2+)-buffered with high concentrations of either EGTA (60 mM) or BAPTA (30 mM). 2. ICa decayed to a steady-state level somewhat less than zero. Inactivation was most rapid at a potential 10 mV more negative than that which elicited the maximal ICa. 3. Involvement of current-dependent processes (i.e. tubular Ca2+ depletion and Ca2+ entry-dependent inactivation) in determining the decay of ICa was excluded, since inactivation was not affected by replacing Ca2+ with Ba2+ or when the size of ICa was reduced by decreasing the [Ca2+]o. Partial block of Ca2+ channels with nifedipine slowed inactivation. This was, however, independent of the size of ICa. Furthermore, neither the peak of ICa nor its time constant of decay nor the time course of ICa recovery from inactivation were affected by changing the [Ca2+]i from pCa 10 to 6. 4. ICa was potentiated during a post-pulse preceded by a pre-pulse at potentials ranging from -60 to -30 mV, whereas a U-shaped inactivation curve was observed at pre-pulse potentials more positive than -30 mV. This curve was asymmetric, since the ascending branch stabilized at a level less than unity. The U-shaped form of the curve depended on post-pulse voltage: it became more pronounced when the post-pulse depolarization increased. Moreover, the activation and inactivation kinetics of ICa during the post-pulse differed from control values. Similar results were found when Ca2+ was replaced with Ba2+. 5. The ICa recovery from inactivation was voltage dependent from -50 to -80 mV; it was voltage independent at more negative potentials, proving that recovery includes a voltage-independent step. 6. The asymmetric U-shaped inactivation curve can be reproduced by a four-state cyclic model without assuming a Ca(2+)-dependent step. Taking into account that recovery from inactivation includes a voltage-independent step which becomes rate limiting at extreme negative potentials, and that during the post-pulse the activation kinetics is faster, we propose a model which has six states, two closed, one open and three inactivated.

Animals↗
PubMed1990

Seasonal variation of serotonin content and nonassociative learning of swim induction in the leech Hirudo medicinalis.

It is possible to obtain habituation of swim induction by stimulating the leech with repetitive light electrical trains. After obtaining this simple form of non-associative learning, it is also possible to potentiate its response by a series of nociceptive skin brushings (dishabituation). Serotonin applied to the animal is the only neurotransmitter found to mimick dishabituation. We have observed that in the period April-June most animals did not exhibit potentiation of the swimming response after nociceptive stimulation while injection of serotonin mimicked dishabituation as in the animals treated in the period October-March. We have seen correlation between the changes in nonassociative learning and the seasonal variation of serotonin levels in segmental ganglia. This finding strengthens the hypothesis of serotonin as the neurotransmitter mediating dishabituation in swim induction of the leech.

Animals↗
PubMed1988

[Pseudotumorous "skip area" in subtotal hepatic steatosis. Echographic and computed tomographic aspects].

In 75 patients ultrasound (US) demonstrated fatty infiltration of the liver with diffuse increased echogenicity except for a solitary hypoechogenic area located in the quadrate lobe. The liver was also followed-up with US, computed tomography (CT), radionuclide scintigraphy, and fine needle biopsy: a skip area unaffected by steatosis was thus demonstrated. This study and further information found in literature allowed the authors to identify the particular US features which lead to a correct interpretation of these findings, which might otherwise be incorrectly diagnosed as suggestive of substitutive lesions (primary or secondary). These features are: 1) the location of skip areas, usually in the IV segment, in close relationship to a portal vessel; 2) their morphology, triangular, or inverted-V shaped; 3) the absence of mass effects upon the hepatic border and/or upon the adjacent vessels; 4) the presence of fatty liver infiltration; 5) the coexistence of a biohumoral pattern significant for diffuse hepatopathy; 6) the lack of change in US patterns during the follow-up.

Biopsy↗
PubMed1988

[Ultrasonics in the diagnosis of hyperplastic cholecystoses of focal and segmental extension type].

The authors describe the sonographic (US) patterns of hyperplastic cholecystoses observed from January 1983 to April 1987 - 39 cases of focal extension and 12 of segmental extension--and confirm the higher sensibility of US versus oral cholecystography. Sonography (SG) allows a straight visualization of the gallbladder wall and its lesions, both in case of limited thickening of the wall (focal cholecystosis) and in case of more extensive thickening (segmental cholecystosis). To cholecystographic findings of focal lesions, SG gives additional information, adding a fundamental diagnostic element: the lack of acoustic shadowing distal to the nodular masses. Nonetheless, SG does not allow a discrimination between focal cholesterolosis and adenomyomatosis, except for particular cases, such as multiple nodular masses, and coexistence with the "comet tail" pattern--the latter due to parietal deposits of cholesterol. Furthermore, the differential diagnosis of focal cholecystoses includes some neoplasms of the gallbladder, and gallstones stuck to the wall, with no acoustic shadowing. In segmental cholecystoses, the direct evaluation of the entity and extension of the wall thickening remains a fundamental diagnostic element, even though such a morphologic detail is often integrated by the functional relieve of hypercontractility of the gallbladder wall after a fatty meal (both oral cholecystography and SG demonstrate it).

Diagnosis, Differential↗
PubMed1986

[Echotomography in Crohn disease].

The authors report their experience in 40 patients with intestinal Crohn's disease, who underwent both abdominal ultrasound scanning and double-contrast small bowel enema. The various echographic patterns are described, found in the different phases during the evolution of Crohn's disease, underlying the importance of ultrasound in evaluating the real degree of bowel wall thickening and the exo-enteral space, only indirectly appreciated with X-ray examination.

Crohn Disease↗
PubMed1981

[Preparation of patients in diagnostic contrast radiography of the urinary and bile tracts and the large intestine].

A preparation schedule including, for clysterisation, a substance based on palmitate, stearate and oleate of sodium of vegetable origin has been experimented in 130 patients of both sexes (70 awaiting contrastography of the urinary and bile ways, and 60 double contrastography of the colon). Excellent results were obtained in urography and colangiocholecystography when the schedule was limited to just one clyster with double dose of Radioced carried out on the same morning as the investigation. For an examination like double contrast clyster, which is more demanding from the viewpoint of correct intestinal cleansing, the number of clysters has to be increased to four. Three, at appropriate intervals, are carried out on the day preceding examination, and the last no more than two hours prior to the clyster. In all four, a double dose of Radioced dissolved in warm water (two litres for each of the first three and a litre and a half for the fourth) is used. Still on double contrast clyster, the preparation schedule requires a three-day diet (the first two involving low-waste foods and the third a liquid diet only) plus 30 g of Epsom salts (and no less than a litre of water) the day before double contrastography.

Cholangiography↗