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C Castellano

Publications and source records attributed to C Castellano.

At least 19 recordsLinked to original sources
PubMed2001

Spatiotemporal distribution of nucleation events during crystal growth.

We consider irreversible second-layer nucleation that occurs when two adatoms on a terrace meet. We solve the problem analytically in one dimension for zero and infinite step-edge barriers, and numerically for any value of the barriers in one and two dimensions. For large barriers, the spatial distribution of nucleation events strongly differs from rho(2), where rho is the stationary adatom density in the presence of a constant flux. Theories of the nucleation rate omega based on the assumption that it is proportional to rho(2) are shown to overestimate omega by a factor proportional to the number of times an adatom diffusing on the terrace visits an already visited lattice site.

Journal Article↗
PubMed2001

Effects of MK-801 and nicotine combinations on memory consolidation in CD1 mice.

RATIONALE: Recent experiments have shown that pre-trial administrations of nicotine to rats tested in a 16-arm radial maze attenuated the MK-801-induced deficit in both working and reference memory performance. Memory consolidation can be influenced in laboratory animals, by post-training administration of drugs. OBJECTIVE: In the present study we have investigated the effects on memory consolidation of CD1 mice exerted by: a) the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclo-hepten-5, 10-imine-maleate] b) nicotine, and c) combinations of MK-801 and nicotine. METHODS: Different groups of mice were injected intraperitoneally (IP) with the single drugs and with their combinations, immediately after training in a passive avoidance task. Additional groups of animals were also injected 2 h post-training with the highest effective dose of MK-801 (0.3 mg/kg), with the highest effective dose of nicotine (0.5 mg/kg) or with the combination of an otherwise ineffective dose of MK-801 (0.1 mg/kg) with the highest effective dose of nicotine, respectively. Their performances were compared with those of mice injected with saline, with the vehicle of nicotine and with the other treatment combinations, respectively RESULTS: The results showed that MK-801 exerted deleterious effects, while nicotine exerted facilitatory effects on mice performances. Further, an otherwise ineffective dose of MK-801 (0.1 mg/kg) antagonized the facilitatory effects of nicotine (0.25 and 0.5 mg/kg). In the 2 h post-training injected groups the treatments were ineffective, showing that the immediate post-training drug administrations affected memory consolidation processes. CONCLUSIONS: In conclusion, from the present research, it is evident that NMDA glutamate and nicotinic acetylcholine receptor systems interact in modulating memory consolidation in CD I mice.

Animals↗
PubMed2001

Pharmacological evidence of muscarinic-cholinergic sensitization following chronic stress.

RATIONALE: Although much evidence supports a major role of brain cholinergic transmission in memory consolidation processes, little is known about cholinergic functioning under environmental pressure. OBJECTIVES: The present experiments were aimed at investigating possible functional adaptation of muscarinic receptors promoted by a chronic stressful procedure in an inbred strain of mice highly susceptible to stress. METHODS: We tested the effects of post-trial administration of a cholinergic agonist and a muscarinic antagonist on the retention of a passive avoidance task in control animals and compared these effects with those observed following food restriction. RESULTS: Food restriction enhanced the facilitatory effects of oxotremorine and reduced the impairing effects of atropine on memory consolidation. CONCLUSION: Our results support the view that chronic sensitization of muscarinic receptors occurs following chronic stress.

Animals↗
PubMed2001

NMDA receptors and learning and memory processes.

In the first part of this review studies are considered in which pre- or post-training peripheral or intracerebroventricular administrations of competitive or noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists were carried out in a variety of animal species tested in different experimental conditions, in order to investigate the effects of these drugs on acquisition and memory processes. In particular, post-training treatments, which are known to affect memory consolidation, ruling out the possible "aspecific effects" linked to the pre-training administrations, show that the NMDA receptor antagonists impair memory in animals tested in various tasks. Memory impairments are also evident when the NMDA antagonists (in particular AP5) are injected into different brain structures, including amygdala and hippocampus. In a second part of this review some recent studies are considered showing the existence of: a) cholinergic-glutamatergic interactions; b) interactions between NMDA receptors and opioid system, and c) interactions between NMDA receptor antagonists (MK-801) and cocaine, in the modulation of memory processes of laboratory animals. The results of some studies showing the involvement of glutamatergic mechanisms in Alzheimer's disease are finally reported, and the therapeutic efficacy of glutamatergic drugs in the treatment of this disease is considered.

Alzheimer Disease↗
PubMed2000

Nonequilibrium phase transition in a model for social influence

We present extensive numerical simulations of the Axelrod's model for social influence, aimed at understanding the formation of cultural domains. This is a nonequilibrium model with short range interactions and a remarkably rich dynamical behavior. We study the phase diagram of the model and uncover a nonequilibrium phase transition separating an ordered (culturally polarized) phase from a disordered (culturally fragmented) one. The nature of the phase transition can be continuous or discontinuous depending on the model parameters. At the transition, the size of cultural regions is power-law distributed.

Journal Article↗
PubMed2000

Strain-dependent interactions between MK-801 and cocaine on retention of C57BL/6 and DBA/2 mice tested in a one-trial inhibitory avoidance task: involvement of dopaminergic mechanisms.

Two sets of experiments were carried out with C57BL/6 (C57) and DBA/2 (DBA) mice tested in a one-trial inhibitory avoidance task. In the first set C57 and DBA mice were injected posttraining with saline or with the D1 DA receptor antagonist SCH 23390 and then with saline, cocaine (5 mg/kg), MK-801 (0.1 mg/kg), or with a combination of these two drugs. Cocaine enhanced retention in the C57 strain and impaired it in the DBA strain, and MK-801 potentiated the effects of cocaine in both strains. Furthermore, pretreatment with SCH 23390 completely antagonized the potentiation of the effects of cocaine exerted by MK-801. In the second set of experiments mice belonging to these same two strains were injected posttraining with vehicle or with the D2 DA receptor antagonist (-)-sulpiride and then with saline, cocaine (5 mg/kg), MK-801 (0.1 mg/kg), or with a combination of these two drugs. Pretreatment with the D2 DA receptor antagonist completely antagonized in both strains the potentiation of the effect of cocaine exerted by MK-801. The results of the present research show that the noncompetitive NMDA receptor antagonist MK-801 enhances the effect of cocaine on retention performance in C57 and DBA mice and that dopaminergic mechanisms are involved in this potentiation.

Animals↗
PubMed1999

MK-801-induced disruptions of one-trial inhibitory avoidance are potentiated by stress and reversed by naltrexone.

Five experiments were carried out to investigate opioid and NMDA receptor-mediated responses to one-trial inhibitory avoidance training in CD1 mice. In the first experiment immediate posttraining intraperitoneal administration of the noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 impaired the performance of mice. The effects of MK-801 were time-dependent (they were absent in mice injected with the drug starting 120 min after training). No effect was evident in no-foot-shock groups, showing lack of proactive influence of the treatment on performance. In the second experiment preexposure of the mice to the testing apparatus decreased the effects of MK-801. In the the third experiment naltrexone antagonized the effects of MK-801, suggesting an involvement of opioid neurons. In the fourth experiment immediate posttraining immobilization stress exerted a potentiating effect on the performance of MK-801-injected animals. In the fifth experiment the potentiation of the impairing effect of MK-801 induced by immobilization stress was antagonized by naltrexone.

Animals↗
PubMed1999

Strain-dependent effects of MK-801 on passive avoidance behaviour in mice: interactions with morphine and immobilization stress.

RATIONALE: Post-training treatments (drugs, stress, ECS) influence retention performance of laboratory animals, sometimes in a strain-dependent way. In a previous study, an interaction between the effects of morphine and of the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 on retention performance was observed, in random bred mice. OBJECTIVE: In the present research, we have investigated the effects on retention of C57BL/6 (C57) and DBA/2 (DBA) mice exerted by a) morphine, b) MK-801 and c) naltrexone. Further, we have studied in both strains the effects exerted on retention by combinations of morphine and MK-801, and of MK-801 and immobilization stress. Finally, the naltrexone-reversibility of the interaction between immobilization stress and MK-801 was also assessed. METHODS: All treatments were administered immediately after training in mice tested in a passive avoidance task. Drugs were injected IP. RESULTS: The results of our experiments showed that morphine and the non-competitive NMDA receptor antagonist MK-801 exerted dose- and time-dependent facilitatory effects on retention performance in C57 mice, and dose- and time-dependent impairments in DBA mice. Further, dose- and time-dependent deleterious effects on retention performance, in the C57 strain, and dose- and time-dependent enhancing effects, in the DBA strain, were observed following post-training IP naltrexone administration. MK-801 enhanced, in both strains, the effects of morphine. Finally, immobilization stress enhanced in both strains the effects of MK-801 and these effects were naltrexone-reversible. CONCLUSIONS: In conclusion, the results of this study show that the genetic make-up of the mice played an important role in all the effects observed, and, in particular, in the interaction between the opioid and the glutamatergic systems. Further, the naltrexone reversibility of the interaction between MK-801 and immobilization stress suggests that opioid mechanisms were involved.

Animals↗
PubMed1999

Strain-dependent involvement of D1 and D2 dopamine receptors in muscarinic cholinergic influences on memory storage.

These experiments examined the interaction of muscarinic and dopaminergic systems in influencing memory for one-trial inhibitory avoidance training in mice of the C57BL/6 and DBA/2 strains. In both strains, immediate post-training systemic administration of the muscarinic cholinergic agonist oxotremorine enhanced retention and the cholinergic antagonist atropine impaired retention. No effects were seen with injections 2 h post-training. Furthermore, the drugs did not affect retention performance of animals that received no footshock on the training trial. These results confirm previous findings indicating that muscarinic cholinergic drugs affect memory by influencing memory consolidation. In C57 mice, pretreatment with selective D1 or D2 dopamine (DA) receptor agonists (SKF 38393 or LY 171555, respectively) in otherwise non-effective doses (5 and 0.25 mg/kg, respectively) potentiated the effects of oxotremorine (0.04 mg/kg). Furthermore, in C57 mice pretreatment with selective D1 or D2 receptor antagonists (SCH 23390 or (-)-sulpiride) in otherwise non-effective doses (0.025 and 6 mg/kg, respectively) blocked the memory enhancing effects of oxotremorine. The memory impairing effects of atropine (3 mg/kg) were blocked by the D1 and D2 selective agonists and potentiated by the selective D1 or D2 antagonists. In contrast, in DBA mice, the D1 and D2 selective agonists antagonised the memory enhancing effects of oxotremorine (0.02 mg/kg) and potentiated the effects of atropine (2 mg/kg). Furthermore, the D1 and D2 antagonists potentiated the effects of oxotremorine and antagonised those of atropine. These findings indicate that although muscarinic cholinergic influences on memory storage are comparable in mice of these two strains, the cholinergic-dopaminergic interactions are opposite in the two strains. These results have implications for hypotheses of cholinergic and dopaminergic regulation of memory storage.

Animals↗
PubMed1999

Strain-dependent effects of anandamide on memory consolidation in mice are antagonized by naltrexone.

Post-training administration of anandamide (1.5, 3, 6 mg/kg) dose-dependently impaired retention of an inhibitory avoidance response in DBA/2 mice, while improving it in C57BL/6 mice. The effects on retention performance induced by the drug appear to be due to an effect on memory consolidation. They were observed when drug was given at short, but not long, periods of time after training, i.e. when the memory trace was susceptible to modulation. These effects of anandamide parallel those of opioid agonists, as previously reported. Moreover, the opioid antagonist naltrexone improved retention in DBA/2 mice, while impairing it in C57BL/6 mice. Pre-treatment with the opioid antagonist at a non-effective dose (0.1 mg/kg) antagonized the effects of anandamide on memory consolidation in both strains. These results strongly suggest that endogenous cannabinoids affect memory processes through opioid systems. The possible involvement of other neurotransmitter systems, such as dopamine, in strain-dependent effects of anandamide in memory consolidation is discussed.

Animals↗
PubMed1999

Scale invariant dynamics of surface growth.

We describe in detail and extend a recently introduced nonperturbative renormalization group (RG) method for surface growth. The scale invariant dynamics which is the key ingredient of the calculation is obtained as the fixed point of a RG transformation relating the representation of the microscopic process at two different coarse-grained scales. We review the RG calculation for systems in the Kardar-Parisi-Zhang (KPZ) universality class and compute the roughness exponent for the strong coupling phase in dimensions from 1 to 9. Discussions of the approximations involved and possible improvements are also presented. Moreover, very strong evidence of the absence of a finite upper critical dimension for KPZ growth is presented. Finally, we apply the method to the linear Edwards-Wilkinson dynamics where we reproduce the known exact results, proving the ability of the method to capture qualitatively different behaviors.

Journal Article↗
PubMed1997

Ifosfamide plus cisplatin as primary chemotherapy of advanced ovarian cancer.

We have performed a phase II study to evaluate the activity and toxicity of ifosfamide and cisplatin as first-line treatment for advanced ovarian cancer. Patients were treated with cisplatin 100 mg/m2 on day 1 and ifosfamide 5 g/m2 in 18-hr continuous infusion on day 1 or 1.5 g/m2 bolus on days 1-5. Between August 1988 and March 1990, 30 women were entered in the trial, 26 of them with measurable disease. The overall clinical response rate was 69% (95% CI: 48-85%), including 34.6% complete responses (95% CI:17-55%). Reassessment laparotomy was performed in 12 cases, and 4 (33%) exhibited a pathologic complete response. For all patients, the median duration of progression-free survival was 14 months, and the median overall survival was 25 months. There were no major differences in the response rate or survival between the two ifosfamide administration modalities. Relevant toxicities were grade IV hematologic toxicity in 11/30 patients and grade IV renal toxicity in 2/30 patients. A patient with grade IV encephalopathy developed a trauma-related cerebral hemorrhage and died 2 months later. The combination of ifosfamide and cisplatin is active in first-line therapy in advanced ovarian cancer, although it does not seem to improve the efficacy or toxicity profile of conventional combinations.

Adult↗
PubMed1997

Impairments produced by amphetamine and stress on memory storage are reduced following a chronic stressful experience.

Post-training administration of the psycho-stimulant, amphetamine or post-trial exposure to restraint stress impaired retention of an inhibitory avoidance response in DBA/2 (DBA) mice. The effect of amphetamine was dose-dependent (1-3 mg/kg) whilst the effect of stress depended on restraint duration (15, 30, or 60 min). Both effects on retention performance appeared to be due to an effect on memory consolidation. In fact, they were observed when the drug and the stressor were experienced at short, but not long, periods of time after training, which is when the memory trace is susceptible to modulation. Moreover, these effects could not be ascribed to a rewarding or non-specific action of the two treatments on retention performance, as the latencies during the retention test of those mice that had not received a footshock during the training, were not affected by the post-training treatments. Administration of either D1 (SCH23390) or D2 [(-)-sulpiride] dopamine (DA) receptor against prior to amphetamine injection or stress exposure antagonized the impairing effects of both treatments. These data indicate that brain dopamine was involved in both cases. Finally, when mice were food restricted for 13 days than allowed free access to food for 24 h before training, either the effects of amphetamine or restraint stress were reduced. Food restricted mice did not differ from control for stepthrough latencies either on the training or the test days, indicating the absence of amnesic or otherwise impairing effects of the experimental procedure per se. Instead, the results indicated hyposensitization to the effects of amphetamine and stress on memory consolidation in food restricted animals.

Amphetamine↗
PubMed1997

MK-801 potentiates morphine-induced impairment of memory consolidation in mice: involvement of dopaminergic mechanisms.

The purpose of the present research was to study the interaction between the non-competitive NMDA receptor antagonist MK-801 and morphine in memory consolidation. The involvement of dopamine (DA) mechanisms in this interaction was also studied. Four sets of experiments were carried out with CD1 mice in a one-trial inhibitory avoidance task with post-training injections of drugs. In a first series of experiments post-training administration of morphine or of the non-competitive NMDA receptor antagonist MK-801 impaired memory consolidation. In the second set of experiments the memory consolidation impairment exerted by MK-801 was potentiated by the administration of the D1 dopamine (DA) receptor antagonist SCH 23390 and by that of the D2 DA receptor antagonist (-)-sulpiride. In the third set of experiments, administration of a dose of MK-801 ineffective by itself potentiated the memory impairment exerted by morphine. In the fourth series of experiments, similar ineffective doses of the D1 DA receptor agonist SKF 38393 or of the D2 DA receptor agonist LY 171555 antagonized the impairment of memory consolidation produced by MK-801 and morphine in combination, suggesting the involvement of dopaminergic mechanisms.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

Strain-dependent effects of D2 dopaminergic and muscarinic-cholinergic agonists and antagonists on memory consolidation processes in mice.

The interaction between muscarinic-cholinergic and dopaminergic systems in the modulation of memory storage of Y-maze discrimination (YMD) task was examined in C57BL/6 and DBA/2 strains of mice. In C57BL/6 mice, post-training systemic (i.p.) administration of the D2-agonist quinpirole facilitated retention and the D2-antagonist (-)-sulpiride impaired retention. Opposite effects were observed in DBA/2 strain. The facilitating or impairing effects of quinpirole and (-)-sulpiride were blocked by simultaneous post-training administration of muscarinic-cholinergic agonists and antagonists. The memory enhancing effects of the cholinergic agonist oxotremorine were not blocked by simultaneous administration of sulpiride in C57BL/6 mice or quinpirole in DBA/2 mice. Furthermore, the memory impairing effects of the cholinergic antagonist atropine were not blocked by simultaneous administration of quinpirole in C57BL/6 mice or sulpiride in DBA/2 mice. These findings indicate that the effects of D2-receptor agonists and antagonists on retention of YMD task are strain-dependent and mediated through muscarinic-cholinergic mechanisms.

Animals↗
PubMed1997

The effects of anandamide on memory consolidation in mice involve both D1 and D2 dopamine receptors.

Post-training administration of anandamide (1.5, 3, 6 mg/kg) dose-dependently impairs the retention of an inhibitory avoidance response in mice. The effects on retention performance induced by the drug appear to be due to an effect on memory consolidation, as they were observed when drugs were given at short, but not long, periods of time after training, i.e. when the memory trace was susceptible to modulation. Pretreatment with either selective D1 or D2 dopamine (DA) receptor agonists, SKF 38393 and quinpirole, at doses that were ineffective when given alone (5 and 0.25 mg/kg, respectively), antagonized the effects of anandamide on memory consolidation, suggesting that D1 and D2 receptors are similarly involved in the effects of anandamide on memory consolidation. These results are discussed in terms of a possible inverse relationship between the modulation of memory processes by endogenous cannabinoid and DA systems.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗