PubMed Health⌕ Search

Biomedical subjects

C Bonardi

Publications and source records attributed to C Bonardi.

18 recordsLinked to original sources
PubMed2006

Palliative surgery for recurrent bowel obstruction due to advanced ovarian cancer.

AIM: Intestinal obstruction is a frequent event in patients affected by ovarian carcinoma. Little data on repeat palliative surgery for recurrent bowel obstruction are available. The aim of this study was to analyze postoperative and long term outcomes of ovarian cancer patients who underwent reoperation for recurrent intestinal obstruction. METHODS: We retrospectively evaluated the records of these patients treated at our Department between 1992 and 2002. RESULTS: Nine women with a mean age of 56 years (range 37-72) were identified. All patients had undergone previous abdominal surgery for bowel obstruction from ovarian cancer. All patients underwent exploratory laparotomy. In 4 patients (Group A) because of advanced disease, only exploratory surgery was carried out. A surgical correction was achieved in the other 5 patients (Group B), but only 3 patients had a successful palliation, defined as the ability to tolerate an oral intake for at least 60 days postoperatively. Postoperative mortality was nil, morbidity was 44.4%; particularly 2 patients developed an enterocutaneous fistula. Mean survival of Group A and B patients were 36.7 and 96.2 days respectively. The 3 successful palliated patients died of disease after 3.5, 4 and 5 months, in 2 cases for recurrent bowel obstruction. CONCLUSIONS: Repeat surgery for recurrent bowel obstruction in advanced ovarian carcinoma may achieve successful palliation in few cases and is associated with high postoperative morbidity and limited survival. In these patients non surgical approaches based on medical treatment, percutaneous endoscopic gastrostomy and stent placement should be considered.

Adult↗
PubMed2003

Alteration of hypothalamus-pituitary-adrenal gland axis in colorectal cancer patients. Preliminary report.

AIM: In advanced cancer patients a cell-mediated immunological impairment, both at baseline and during postoperative period, is often found and is associated with poor prognosis. Cortisol is strictly involved in the response to major surgical stress, is an immunosuppressor and causes a redistribution of immunological population cells in different tissues. The aim of the study was to verify serum levels and circadian rhythm of cortisol in patients with colorectal cancer at baseline before surgery and in the postoperative period, and relate it to the immune status. METHODS: In 21 patients with colorectal cancer undergoing surgery we evaluated the assessment of total lymphocytes, CD4+, cortisolemia, circadian rhythm of cortisol (11 p.m. and 8 a.m.) at baseline and in 3(rd) and 7(th) postoperative days. RESULTS: Increase of cortisolemia, as decrease of total and CD4+ lymphocytes in the postoperative period versus baseline was statistically significant. Patients with an altered circadian rhythm were 47% and 36% at 3rd and 7th postoperative days, respectively. At baseline 19% of patients had an altered cortisol circadian rhythm and it was more frequent in patients with nodal involvement (p<0.05) and with metastasis (p<0.01). No relations between lymphocytopenia and alteration of cortisolemia and cortisol circadian rhythm were found, either at baseline or postoperatively (p<0.05). CONCLUSION: Lymphocytopenia in cancer patients seems not to be associated with cortisol level and circadian rhythm alteration, either at baseline or after surgical stress. An impairment of circadian rhythm of cortisol was found at baseline in 19% of patients. It was significantly associated with the presence of metastatic disease.

Adenocarcinoma↗
PubMed2001

Dorsal hippocampal lesions impair appetitive classical conditioning to localized cues.

Three experiments examined appetitive classical conditioning in rats with small electrolytic lesions of the dorsal hippocampus. In all the experiments, the reinforcer was food delivery and the conditioned response (CR) entry to the food tray; the three experiments differed in the nature of the conditioned stimulus (CS). When this was a small light located inside the food tray, conditioning was impaired in lesioned animals, but when the CS was a general increase in illumination, they learned at the same rate as controls. With a white noise as the CS, learning was significantly faster in lesioned subjects. These data demonstrate that lesions of the dorsal hippocampus can produce impairments in appetitive delay conditioning, but only with certain types of CS. It is suggested that deficits are found with CSs that are localized in space.

Animals↗
PubMed1996

Contextual control of conditioned responding in rats with dorsal hippocampal lesions.

The control exerted by contextual cues over classically conditioned responding was assessed for rats with electrolytic lesions of the dorsal hippocampus and sham-operated controls. In 3 experiments the rats received initial training with 2 reinforced cues, each presented in its own distinctive context, followed by a nonreinforced test in which the cues were presented in the other context. Both control and operated subjects showed context specificity, as evidenced by less vigorous responding to these cues than to cues presented on test in their original contexts. The groups did not differ in their ability to learn an explicit discrimination in which a given cue was reinforced in one context and nonreinforced in a different context (although the groups did differ on a simple autoshaping task). It is concluded that a special role for the hippocampus in the contextual control of conditioned responding still remains to be demonstrated.

Animals↗
PubMed1995

Role of stimulus ambiguity in conditional learning.

Three experiments using rats and the conditioned emotional response procedure examined the notion that when a conditioned stimulus (CS) is paired with a reinforcer (US), that CS must be ambiguous if the CS-US association is to become the target of conditional control. CS ambiguity was manipulated by varying whether the CS had been preexposed prior to conditioning. In Experiments 1 and 2, it was demonstrated that a cue that accompanied pairings of a CS and shock acquired conditional control over the CS-shock association when that CS had been preexposed, but not when it was novel. The measure of conditional control in Experiments 1 and 2 was the ability of the (conditional) cue to enhance responding to the target CS. Experiment 3 used a blocking procedure to show that this enhancement reflected an amplification of the target CS's effective associative strength. These findings extend existing knowledge of the conditions required for conditional cue formation.

Animals↗
PubMed1995

Enhancement of latent inhibition in rats with electrolytic lesions of the hippocampus.

Two groups of rats--1 with electrolytic lesions of the hippocampus and 1 consisting of sham-operated controls--received flavor-aversion conditioning with 2 flavors. All subjects had received prior nonreinforced exposure to Flavor A. Latent inhibition was apparent in slower acquisition of the aversion to Flavor A than to Flavor B. Hippocampal lesions had no effect on acquisition to the nonpreexposed Flavor B but produced a marked enhancement of the latent inhibition effect. The contrast between this result and previous findings of an attenuation of latent inhibition in subjects with hippocampal lesions is discussed.

Animals↗
PubMed1994

Discriminative inhibition is specific to the response-reinforcer association but not to the discriminative stimulus.

In 4 experiments an instrumental contingency between a response and a reinforcer was introduced in the presence of a discriminative stimulus. Then a discriminative inhibitor (S delta) was established that signaled that the instrumental contingency would no longer operate in the presence of that discriminative stimulus, so that the S delta suppressed operant responding. The degree to which the S delta, s inhibitory properties transferred to different discriminative stimuli and different response-reinforcer associations was then explored. In Experiments 1 and 2 the S delta, s effects transferred perfectly to a 2nd discriminative stimulus, whereas the results of Experiments 3 and 4 were consistent with the hypothesis that the S delta, s inhibitory properties were specific to the original response-reinforcer association. The theoretical implications of these findings are discussed.

Animals↗
PubMed1994

Occasion-setting training renders stimuli more similar: acquired equivalence between the targets of feature-positive discriminations.

In two experiments rats received training on two concurrent appetitive feature-positive discriminations. A preliminary test in Experiment 1 confirmed previous demonstrations of the transfer of occasion-setting properties--the feature from one of these discriminations was better able to facilitate responding to the occasion-set target CS from the second discrimination than to a control stimulus that had not been the subject of occasion-setting. The source of this transfer was investigated in a second phase of training, and in Experiment 2. In both experiments one of the occasion-set CSs was paired with food, and generalization of appetitive conditioned responding from this stimulus to the second occasion-set CS, and to a control cue, was examined. There was more generalization from the first occasion-set CS to the second CS that had also been occasion-set than to the control cue. This is taken as evidence that occasion-set CSs are rendered more similar as a result of their common training history. The implications of these findings for explaining transfer of occasion setting are discussed.

Animals↗
PubMed1993

Negative priming in associative learning: evidence from a serial-conditioning procedure.

Three experiments investigated the suggestion that a predicted or primed stimulus commands less processing and consequently elicits a weaker conditioned response (CR) than a stimulus that is not primed. In each experiment rats received initial training in which the presentation of each of 2 serial compounds, A-X and B-Y, was followed by the delivery of food. Subsequently, X's capacity to elicit the CR, approaching the site of food delivery, was assessed when X was preceded by Stimulus A (i.e., primed) or was presented after Stimulus B. Stimulus X elicited a more vigorous response when it was presented after B than when it followed A. These results show that the ability of one event to elicit its CR is reduced if its presentation has been predicted by some other event. This negative priming effect supports one aspect of Wagner's (1981) model of Pavlovian conditioning.

Animals↗
PubMed1993

Acquired equivalence between cues trained with a common antecedent.

In Experiment 1, rats experienced 2 stimuli (A and N) each preceded by the same event (food) or by different events (food preceded 1 but not the other). N was then paired with shock, and the generalization of conditioned suppression to A was assessed. Generalization was more marked when A and N had been experienced along with a common antecedent. In Experiment 2, 3 stimuli (A, B, and N) were presented in initial training. For 1 group, A and N were preceded by food and B was not; for a 2nd group A alone was preceded by food. In each group, suppression generalized more readily from N to the stimulus that had received the same initial training as had been given to N. Experiment 3 found that generalization was not enhanced between stimuli when 1 had preceded food in initial training and 1 had followed it. These results demonstrate that stimuli that have shared a common antecedent will come to be treated as equivalent.

Animals↗
PubMed1989

Inhibitory discriminative control is specific to both the response and the reinforcer.

In two experiments an S delta was established which signalled the absence of an instrumental contingency between a particular response, R1, and a particular reinforcer, Rf1. The S delta suppressed operant responding, and the specificity of this suppression to the elements of the response-reinforcer association, R1 and Rf1, was explored. Experiment 1 showed that the S delta suppressed performance of R1 more effectively than it suppressed performance of a second response, R2. Experiment 2 showed that the S delta suppressed performance of a response rewarded with Rf1 more effectively than it suppressed performance of a response that had been rewarded with a second reinforcer, Rf2. These results suggest that an S delta's suppressive effects are specific to the particular response and reinforcer, which were uncorrelated in its presence during training. The implications of these results for theories of inhibitory discriminative control and for theories of occasion setting are discussed.

Animals↗
PubMed1979

[Blood in CPD].

Explore the source record for details and available documents.

Anticoagulants↗