Avoidance Situation Research Articles

Análisis de las causas de los reingresos en un hospital de agudos y su evitabilidad potencial

Rates of hospital readmissions are used as indicators of quality of health care. Yet specific causes of readmissions have not been sufficiently studied and an unified definition of such an indicator is lacking. Our goal was to determine the causes and potential avoidability of readmissions in our hospital and to identify a suitable definition of this indicator. Cross sectional study. Hospital Costa del Sol (Marbella, Málaga). Subjects of study: Random sample of hospital discharges followed by a new admission within the next 6 months (n = 363). Determination of the causes and potential avoidability of readmissions, by means of a peer-review of medical records. Descriptive and logistic regression analysis of the variables contained in the Minimum Basic Data Set (MBDS) and related to the avoidability of readmissions. 19% (95% CI: 15.0-23.0) of hospital readmissions within 6 months after hospital discharge were attributed to potentially avoidable situations if the applied medical care had been modified during the previous episode. This figure reached 37% (95% CI: 27.4-47.3) for surgical services, 13% (95% CI: 8.7-17.6) for medical services and 12% (95% CI: 2.9-20.6) for obstetrics. The MBDS variables related to the potential avoidability of readmissions were, for the whole hospital, 1) the shorter interval from the previous discharge and 2) the difference of diagnosis between both episodes. Most hospital readmissions are due to non-avoidable situations if the applied medical care had been modified during the previous episode. In order to detect potentially avoidable situations, definitions of readmission rates should only include early readmissions with a chief diagnosis other than that in the previous admission.

Numerical analysis of optimal vehicle trajectories for emergency obstacle avoidance

Vehicle trajectories for emergency obstacle avoidance are analyzed from a viewpoint of optimal control. The performance function consists of integrals of longitudinal acceleration, lateral acceleration and control effort is defined to formulate the obstacle avoidance problem as an optimal control problem. A numerical optimization method called a direct optimization is applied to calculate the optimal steering program. Using a nonlinear vehicle model, physical constraints such as saturation of control input, inequality constraints for vehicle trajectories, and equality constraints for terminal vehicle states are taken into account. The solutions to the optimal control problem provide valuable insight into the vehicle maneuver at the obstacle avoidance situations.

Behavioural activity of (S)-3,5-DHPG, a selective agonist of group I metabotropic glutamate receptors

The influence of intracerebroventricular (i.c.v.) injections of (S)-3,5-dihydroxyphenyl-glycine (S)-3,5-DHPG, a selective agonist of group I metabotropic glutamate receptors (mGluRs), on the activity of the central nervous system was examined in male rats. (S)-3,5-DHPG at doses of 25, 50 and 100 nmol significantly attenuated crossings of squares and rearings, but not bar approaches, in an ‘open field’ test and failed to change apomorphine-induced stereotypy. (S)-3,5-DHPG at the above doses, given immediately after the learning trial, significantly facilitated the consolidation process in a passive avoidance situation, but given before the learning trial and before the retention testing did not have any influence on acquisition and retrieval processes, respectively. Moreover, (S)-3,5-DHPG did not influence recognition memory evaluated in an object recognition test. These results may suggest that activation of group I mGluRs takes part in the consolidation process in affectively-motivated memory, but is probably not necessary for processing of recognition memory, and that (S)-3,5-DHPG memory facilitation seems to be independent of glutamatergic and dopaminergic interaction.

BILATERAL 6-OHDA LESIONS TO THE HIPPOCAMPUS ATTENUATE THE FACILITATORY EFFECT OF CCK-8 [formula omitted] AND CAERULEIN ON MEMORY IN RATS

The involvement of dopaminergic projection to the hippocampus in the facilitatory effect of cholecystokinin-unsulphated octapeptide (CCK-8 us) and caerulein (CER) on memory motivated affectively was investigated in male rats. CCK-8 us and CER were given subcutaneously at the doses of 10 μg kg−1and 0.5 μg kg−1, respectively, immediately after a single learning trial in a passive avoidance situation, after bilateral 6-OHDA lesions to the dentate gyrus of the hippocampus. In order to protect noradrenergic neurones against destruction by neurotoxin, 30 min before surgery rats were pre-treated intraperitoneally with 25 mg kg−1of desmethylimipramine, an inhibitor of noradrenaline uptake. Bilateral 6-OHDA lesions to the hippocampus significantly attenuate the facilitatory effect of CCK-8 us and CER on retention of passive avoidance behaviour evaluated 24 h after the learning trial. Neither, destruction of dopaminergic endings in the hippocampus, nor application of CCK-8 us and CER changed the spontaneous psychomotor activity of rats estimated in an `open field' test. These results may indicate that the facilitatory effect of CCK-8us and CER on memory motivated affectively is, in part, mediated by dopaminergic projection from the ventral tegmental area to the dentate gyrus of the hippocampus. 2000 Academic Press@p$hr

Improved conditioned avoidance learning by oxytocin administration in high-emotional male Sprague-Dawley rats

Objective: To examine anti-stress-like properties of oxytocin as a means to improve conditioned avoidance learning in a low-performing, high-emotional, stock of Sprague-Dawley male rats. Methods: Adult male rats of two stocks of the Sprague-Dawley strain, designated Stock A and Stock B, were treated daily with oxytocin (1 mg kg −1 s.c.) for 5 days preceding four daily conditioned avoidance acquisition sessions (approximately 20 trials per 15 min session). The Stock B animals were previously characterized as high-emotional based on [1] elevated plasma corticosterone, and lowered plasma oxytocin, levels and [2] decreased reaction time and an increased startle amplitude to an acoustic stimulation. Finally, [3] these animals were unable to acquire a conditioned avoidance response within 5 days of training. Results: The Stock A animals rapidly and statistically significantly acquired the avoidance behaviour within 4 days of daily training, whereas Stock B animals did not improve over this time period. The avoidance performance of Stock B animals was markedly and statistically significantly improved by the oxytocin pre-treatment, whereas the performance of Stock A animals was not affected by the same oxytocin treatment. Conclusions: Pre-treatment with oxytocin markedly improved avoidance learning in the Stock B high-emotional animals. It is suggested that the improvement is due to previously demonstrated anti-stress-like properties of oxytocin, rendering the animals able to successfully cope with the demands of the conditioned avoidance situation.

DISRUPTION OF TEMPORO-ENTORHINAL CONNECTIONS ABOLISHES THE FACILITATORY EFFECT OF ANGIOTENSINS ON MEMORY IN RATS

It has been found in our laboratory that the positive influence of angiotensin II (AII) and its 3–7 fragment [AII(3–7)] on learning and memory processes is mediated by the excitatory amino acids, since it was abolished by NMDA receptor antagonists. The purpose of the present study was to investigate whether bilateral disruption of glutamatergic temporo- entorhinal connections may have an influence on the facilitatory effect of both angiotensin peptides on memory motivated affectively. The bilateral transections of temporo-entorhinal connections were made in 27 male rats 10 days before testing the influence of intracerebroventricular AII and AII(3–7) injection on retrieval of a passive avoidance response. Twenty-seven additional rats served as sham-operated controls. Twenty-five lesioned and 25 sham-operated animals were accepted to the final analysis. AII and its 3–7 fragment significantly improved the retrieval process in sham-operated groups of rats. Bilateral disruption of temporo-entorhinal connections totally abolished the facilitatory effect of both angiotensins on recall of information in a passive avoidance situation. Moreover, bilateral disruption of temporo-entorhinal connections markedly but not significantly attenuated crossings of squares, evaluated in an open field test, without an influence on rearings and bar approaches. These results may suggest that in the facilitatory effect of AII and AII(3–7) on memory motivated affectively involves reciprocal glutamatergic connection between lateral entorhinal cortex and temporal cortex.

DOPAMINERGIC PROJECTION TO THE CENTRAL AMYGDALA MEDIATES THE FACILITATORY EFFECT OF CCK-8US AND CAERULEIN ON MEMORY IN RATS

The involvement of dopaminergic projection to the central amygdala in the facilitatory effect of cholecystokinin unsulphated octapeptide (CCK-8US) and caerulein (CER) on memory motivated affectively was investigated in male rats. CCK-8US and CER were administered subcutaneously at the doses of 10 μg kg−1and 0.5 μg kg−1, respectively, immediately after a single learning trial in a passive avoidance situation, after bilateral 6-OHDA lesions to the central amygdala. Bilateral 6-OHDA lesions to the central amygdala totally abolished the facilitatory effect of CCK-8US and CER on retention of passive avoidance behaviour evaluated 24 h after the learning trial. These results may indicate that the facilitatory effect of CCK-8US and CER on memory motivated affectively is mediated by dopaminergic projection from ventral tegmental area to the central amygdala.1999 Academic Press@p$hr

Dopaminergic Projection to the Nucleus Accumbens Mediates the Memory-Enhancing Effect of Angiotensins in Rats

It has been shown that the facilitatory effect of angiotensin II (AII) and its 3–7 fragment [AII(3–7)] on cognitive processes is mediated by the dopaminergic system. In the present study, the involvement of dopaminergic projection to the nucleus accumbens (NAS) and to the nucleus septi lateralis (NSL) in the expression of the positive effect of AII and AII(3–7) on the retrieval of passive avoidance after bilateral 6-OHDA induced lesions to NAS and NSL was evaluated. To protect noradrenergic neurons from destruction by neurotoxin, rats were pretreated intraperitoneally with 25 mg/kg of desmethylimipramine, an inhibitor of noradrenaline uptake, 30 min before surgery. Both peptides were given intracerebroventricularly, at the dose of 1 nmol each, 15 min before the retention testing. Bilateral 6-OHDA lesions to NAS totally abolished, and to NSL did not affect, the positive effect of angiotensins on recall of information in a passive avoidance situation. Moreover, bilateral 6-OHDA lesions to NAS but not to NSL significantly attenuated the locomotor activity of rats in an open-field test. Nevertheless, it had no essential significance on the evaluation of the influence of the disruption of the dopaminergic endings in both structures on the facilitatory effect of angiotensins on retrieval process. These results suggest that the dopaminergic projection to NAS, but not to NSL is involved in the expression of the facilitatory effect of AII and AII(3–7) on memory motivated affectively evaluated in a passive avoidance situation.

6-OHDA BILATERAL LESIONS TO THE AMYGDALA ABOLISH THE MEMORY ENHANCING EFFECT OF ANGIOTENSIN II IN RATS

The involvement of a dopaminergic projection arriving at the central amygdala (CA) in angiotensin II (AII) facilitation of affectively motivated memory was investigated in male rats. AII was given intracerebroventricularly at a dose of 1 nmol, 15 min before retention testing in a passive avoidance situation after bilateral 6-OHDA lesions to CA. In order to protect noradrenergic neurones against destruction by neurotoxin, 30 min before surgery rats were pre-treated intraperitoneally with 25 mg kg−1of desmethylimipramine, an inhibitor of noradrenaline uptake. Bilateral 6-OHDA lesions to CA totally abolished the facilitatory effect of AII on the retrieval process in a passive avoidance situation, but had no influence on the spontaneous psychomotor activity of rats. These results suggest that the anatomical substrate facilitating the retrieval of the information activity of AII is closely related to the dopaminergic projection arriving at CA.

6-OHDA Lesions to Amygdala and Hippocampus Attenuate Memory-Enhancing Effect of the 3-7 Fragment of Angiotensin II

We have previously shown that facilitatory effect of angiotensin II (AII) on the retrieval of memory is mediated by the dopaminergic system. In the present study, we searched for the influence of the 3-7 fragment of angiotensin II [AII(3-7)] on the retrieval processes in a passive avoidance situation after bilateral 6-OHDA lesions to the central amygdala (CA) and the CA4 field of the hippocampus (HI). AII(3-7) given 15 min before the retention testing, at the intracerebroventricular dose of 1 nmol, significantly prolonged avoidance latencies in sham-operated rats (i.e. improved retrieval of memory for the electric footshock experienced during the learning trial). Bilateral lesions to CA totally abolished, and to HI significantly diminished, this facilitatory effect. An increase of spontaneous locomotor activity in rats lesioned to CA and a decrease in rats lesioned to HI were unlikely to interfere with the cognitive effect of AII (3-7). These results suggest that the anatomical substrate of facilitating retrieval of information activity of AII(3-7) is closely related to the dopaminergic projection from the ventral tegmental area and substantia nigra to CA and HI.

The participation of nitric oxide in the facilitator effect of arginine vasopressin on memory.

In this study we tested the hypothesis that nitric oxide (NO), which function as a novel type of inter-cellular messenger in the central nervous system (CNS) participated in the facilitator effect of arginine vasopressin (AVP) on learning and memory. Recent investigations have provided evidences that inhibition of NO synthesis attenuated the vasodilatation caused by AVP, and inhibited the improvement of learning and memory evoked by angiotensin II. AVP as well as pharmacologically produced increase in endogenous NO facilitates the consolidation of shock avoidance learning. We evaluated the behavioural effects of AVP at dose 1 microgram after the inhibition of NOS by NG-nitro-L-arginine methyl ester (L-NAME) at dose 10 micrograms, and after the injection of endogenous donor of NO -L-arginine- 10 micrograms in the retrieval of passive avoidance situation, and in consolidation of active avoidance responses. The locomotor activity of all investigated drugs was tested in the open field test. AVP facilitated the recall of passive avoidance responses and consolidation of active avoidance responses. Neither the increase of NO concentration after the injection of L-arginine nor the decrease of NO after the inhibition of NOS by L-NAME changed the behavioural effects of AVP. L-arginine increased the psychomotor behaviour and L-NAME decreased the activity of animals in the "open field" test. L-arginine itself improved the consolidation of active avoidance responses. Our results indicate that central action of AVP is probably independent of NO concentration in the brain.

Fuzzy ARTMAP Neural Networks (FAMNN) Based Navigation for Intelligent Autonomous Vehicles (IAV) in Partially Structured Environments

The use of Hybrid Intelligent Systems (HIS) is necessary to bring the behavior of Intelligent Autonomous Vehicles (IAV) near the human one in recognition, learning, decision-making, and action. First, the necessity of HIS and some navigation approaches based on Fuzzy ArtMap Neural Networks (FAMNN) are discussed. Second, a FAMNN based navigation approach, is suggested. Indeed, this approach must provide vehicles with capability, after supervised fast stable learning: Simplified Fuzzy ARTMAP (SFAM), to recognize both target location and obstacle avoidance situations using FAMNN_1 and FAMNN_2, respectively. Afterwards, the decision-making and action consist of two association stages, carried out by reinforcement Trial and Error learning, and their coordination using NN_3. Finally, simulation results which display the ability of the FAMNN based approach providing IAV with capability to intelligently navigate in partially structured environments.

The Effect of Baclofen and AP-7 on Selected Behavior in Rats

Synaptic plasticity, cognitive performance, learning, and memory appear to be determined by the balance between GABAergic inhibitory and glutaminergic excitatory amino acids (EAA). To evaluate this role of amino acids the effects of baclofen (0.5 mg/kg IP), GABA-B receptor agonist and AP-7 (5 nmol ICV)–NMDA ( N-metyl- d-aspartate) receptor antagonist on the processes of retrieval, consolidation of conditioned reflexes, object recognition, and locomotor activity were tested in rats. Neither AP-7 nor baclofen alone changed locomotor activity, but coadministration of AP-7 and baclofen significantly decreased this activity in the open-field test. Neither AP-7 nor baclofen influenced retrieval or consolidation in the passive avoidance situation when administred alone. Significantly prolonged retrieval and consolidation were observed when AP-7 and baclofen were given together. We did not find differences in effects of either AP-7 or baclofen on object recognition, regardless whether administered alone or in combination.

6-OHDA BILATERAL LESIONS TO THE NUCLEUS SEPTI LATERALIS ATTENUATE VASOPRESSIN IMPROVEMENT OF RECALL IN RATS

The investigation was aimed at investigating whether the dopaminergic projection arriving at the nucleus septi lateralis (NSL) is involved in the facilitatory effect of vasopressin (AVP) on memory retrieval. The bilateral 6-OHDA lesions to the NSL were made in 20 male Wistar rats before testing the intracerebroventricular (i.c.v.) AVP injection on recall in a passive avoidance situation. Eighteen additional rats served as sham-operated controls. Thirty minutes before surgery rats were pre-treated with an intraperitoneal injection of 25 mg kg−1of desmethylimipramine, an inhibitor of norepinephrine uptake. Sixteen lesioned and 16 sham-operated rats were included in the study. AVP (1 μg, i.c.v.) given 15 min before the retention testing significantly improved latencies both in lesioned and in sham-operated rats in comparison with the respective i.c.v. saline-injected animals. However, bilateral lesions to the NSL significantly diminished the facilitatory effect of AVP on recall. The insignificant decrease of spontaneous psychomotor activity in rats lesioned to the NSL was unlikely to interfere with the cognitive effect of AVP. These results suggest that dopaminergic projection to the NSL is involved in the facilitatory effect of AVP on the retrieval process in a passive avoidance situation.

Neural Navigation Approach for Intelligent Autonomous Vehicles (IAV)in Partially Structured Environments

The use of Neural Networks (NN) is necessary to bring the behavior of Intelligent Autonomous Vehicles (IAV) near the human one in recognition, learning, decision-making, and action. First, current navigation approaches based on NN are discussed. Indeed, these current approaches remedy insufficiencies of classical approaches related to real-time,autonomy , and intelligence. Second, a neural navigation approach essentially based on pattern classification to acquire target localization and obstacle avoidance behaviors is suggested. This approach must provide vehicles with capability, after supervised Gradient Backpropagation learning, to recognize both six (06) target location and thirty (30) obstacle avoidance situations using NN1 and NN2 Classifiers, respectively. Afterwards, the decision-making and action consist of two association stages, carried out by reinforcement Trial and Error learning, and their coordination using a NN3. Then, NN3 allows to decide among five (05) actions (move towards 30°, move towards 60°, move towards 90°, move towards 120°, and move towards 150°). Third, simulation results which display the ability of theneural approach to provide IAV with capability to intelligently navigate in partially structured environments are presented. Finally, a discussion dealing with the suggested approach and how it relates to some other works is given.

Effects of β-adrenoceptor blocker pindolol, calcium antagonist verapamil and their combination on retention in step-down- and shuttle-box-trained rats and on brain biogenic monoamines

The effects of the β-adrenoceptor blocker pindolol and the calcium antagonist verapamil administered alone or in combination on retention in step-down- and shuttle-box-trained rats and on the biogenic monoamine levels in the frontal cortex and hippocampus were examined. The chronic oral treatment with pindolol impaired retention in step-down- and shuttle-box-trained rats, decreasing the dopamine (DA) and noradrenaline (NA) levels and increasing the serotonin (5-HT) levels in the cortex and hippocampus. Verapamil did not influence retention in step-down- and shuttle-box avoidance situation and the biogenic monoamine levels in the frontal cortex and hippocampus. It should, however, be noted that the chronic oral treatment with verapamil completely abolished the retention-impairing effect of pindolol, restoring to normal DA, NA and 5-HT levels. These findings might be of interest to clinical practice and suggest the necessity for using a combination of β-blockers with Ca 2+ antagonists in case of prolonged treatment of cardiovascular diseases.

Simulation of emergency obstacle avoidance situations using genetic algorithm

Simulation of emergency obstacle avoidance situations using genetic algorithm

6-OHDA bilateral lesions to the central amygdala do not affect vasopressin improvement of recall in rats.

The influence of vasopressin (AVP) on recall of information in a passive avoidance situation after bilateral 6-OHDA lesions to the central amygdala was tested. AVP given 15 min before the retention testing at the icv dose of 1 microgram significantly prolonged avoidance latencies both in lesioned and in sham-operated rats in comparison with the respective icv saline injected animals. Insignificant increase of spontaneous locomotor activity in rats lesioned to the central amygdala was unlikely to interfere with the cognitive effect of AVP. These results suggest that dopaminergic projection to the central amygdala is not responsible for the facilitatory effect of AVP on retrieval process in a passive avoidance situation.

Initial Driver Avoidance Behavior and Reaction Time to an Unalerted Intersection Incursion

Initial driver avoidance behavior and reaction time to an unexpected intersection incursion was determined using a state-of-the-art motion-based driving simulator (Iowa Driving Simulator). The intersection used for the experiment was on a two-lane rural highway (55 mph speed limit) that controlled perpendicular (crossing) traffic by stop signs. The subject vehicle did not have to stop and had the right-of-way on the highway. At one of three possible start times, an intersecting vehicle began moving into the intersection in front of the subject vehicle. This incurring vehicle intersected from either the driver's left or right side. Ninety-six subjects participated in the study. Subjects in the shortest, most severe collision avoidance situation were significantly slower to react and equally likely to steer or release the accelerator pedal as the initial avoidance maneuver. Subjects in the longest, least severe collision avoidance situation often released the accelerator pedal and braked prior to steering. Gender differences are also discussed.

Effect of Ganglioside (GM1) on Memory in Senescent Rats

Monosialoganglioside GM1 (GM1) has been found to alleviate genetic and lesion-induced memory deficits. The purpose of this study was to investigate the effects of 7-day treatment with GM1 (50mg/kg IP) on acquisition and retention performance of senescent rats in a passive avoidance situation. Saline-treated old rats showed a decreased performance in acquisition and retention tests as compared to saline-treated adult rats. GM1 improved both acquisition and retention performance of old animals, and there was no significant difference between GM1-treated old rats and saline-treated adult rats. These data suggest that GM1 treatment can improve memory deficits in intact senescent animals.