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Biomedical subjects

M Migliore

Publications and source records attributed to M Migliore.

At least 19 recordsLinked to original sources
PubMed2001

A single-trocar technique for minimally-invasive surgery of the chest.

BACKGROUND: In thoracic surgery, the classic thoracoscope is used to perform simple maneuvers in the chest. We have devised a minimally invasive technique that requires only a single trocar. This technique is used in our department to diagnose and treat a wide range of thoracic pathologies. METHODS: Between October 1998 and August 1999, 37 patients underwent surgery prospectively for a thoracic disease through a single trocar. There were 19 men and 18 women with a mean age of 60 years (range, 40-85). The trocar was flexible or soft and had a diameter of 15-20 mm. A 2-cm skin incision was made in the planned intercostal space. The chest drain was always inserted under video control. RESULTS: The mean operative time was 53 +/- 5 min. One patient developed intraoperative bleeding that required intubation and a 5-cm mini-thoracotomy. In one patient with stage II empyema, it was necessary to insert another trocar. Chest tubes were removed after 77.7 +/- 7 h. Hospital stay was 4 +/- 1 days (range, 2-14). Histologic examination revealed malignant disease in 26 cases and benign disease in 11. Two patients (5.4%) developed wound infections. None of the patients had port site metastasis. There were no hospital deaths. CONCLUSION: Because of its simplicity, we recommend the use of this mini-invasive technique in place of the classic thoracoscope or video-mediastinoscope.

Adult↗
PubMed2001

Quantitative modeling of perception and production of time intervals.

The accurate perception/production of durations in the seconds and minutes range is important in a number of everyday activities, but the lack of direct experimental evidence on the neural circuits that could be involved has precluded the detailed elucidation of the underlying physiological mechanisms. We show, using a basic biophysical model of a timekeeping system and experimental data on time intervals produced or estimated under different conditions, that experimental values, variability, and distributions can be quantitatively explained in terms of a background synaptic activity such as that generated by attention. The model provides a plausible neural substrate for encoding time intervals, and the findings suggest how it may interplay at the single neuron level with the attentional system, to elaborate a subjective representation of the elapsing time.

Humans↗
PubMed2001

[Recent concepts regarding the treatment of traumatic hemopneumothorax].

BACKGROUND: The aim of the study was to examine the different therapeutic options for traumatic hemopneumothorax and in particular the latest concepts (videothoracoscopy). METHODS: A retrospective study was performed on a group of 20 patients with post-traumatic hemothorax and/or pneumothorax attending the emergency department at Ospedale Vittorio Emanuele in Catania over the past 10 years where 2500 patients with abdominal and/or thoracic trauma were treated during the same period. The patients included 18 males and 2 females with a mean age of 35 years (range 13-70). The cause of injury was a gunshot wound in 8 patients, a blunt trauma following a road accident in 9 and a stab wound in 3 patients. A drainage tube was inserted in 15 patients (a videothoracoscopic approach was used in 2 cases); 3 patients required a diaphragmatic suture and 2 thoracotomy (inferior lobectomy and repair of the main left bronchus). RESULTS: Three out of 20 patients died with an overall mortality rate of 15%. Two patients died respectively from severe brain and abdominal injuries associated with thoracic trauma, while the third patient died from septic complications. CONCLUSIONS: In the past few years videothoracoscopy has allowed a different approach to be used in patients affected by hemo-pneumothorax since it allows a more accurate diagnosis (extent and origin of bleeding, identification of associated diaphragmatic lesion) and the possibility of treating pleuro-pulmonary injuries without performing extensive thoracotomies.

Adolescent↗
PubMed2000

Dendritic potassium channels in hippocampal pyramidal neurons.

Potassium channels located in the dendrites of hippocampal CA1 pyramidal neurons control the shape and amplitude of back-propagating action potentials, the amplitude of excitatory postsynaptic potentials and dendritic excitability. Non-uniform gradients in the distribution of potassium channels in the dendrites make the dendritic electrical properties markedly different from those found in the soma. For example, the influence of a fast, calcium-dependent potassium current on action potential repolarization is progressively reduced in the first 150 micrometer of the apical dendrites, so that action potentials recorded farther than 200 micrometer from the soma have no fast after-hyperpolarization and are wider than those in the soma. The peak amplitude of back-propagating action potentials is also progressively reduced in the dendrites because of the increasing density of a transient potassium channel with distance from the soma. The activation of this channel can be reduced by the activity of a number of protein kinases as well as by prior depolarization. The depolarization from excitatory postsynaptic potentials (EPSPs) can inactivate these A-type K+ channels and thus lead to an increase in the amplitude of dendritic action potentials, provided the EPSP and the action potentials occur within the appropriate time window. This time window could be in the order of 15 ms and may play a role in long-term potentiation induced by pairing EPSPs and back-propagating action potentials.

Action Potentials↗
PubMed1999

Computational model of the effects of stochastic conditioning on the induction of long-term potentiation and depression.

The long-term potentiation (LTP) or long-term depression (LTD) of synaptic strength are currently considered to be the first microscopic steps leading to learning and memory. The great majority of experiments (both in vitro and in vivo) studying the basic mechanisms of LTP and LTD induction use conditioning protocols in which the presynaptic stimuli are delivered at constant frequencies. This is not, however, what is commonly found in vivo, where a highly irregular spiking activity seems to drive most of the neuronal functions. Thus, some important aspects of the induction characteristics of LTP and LTD expressed in vivo might have been overlooked by the experiments. Using a simple schematic model for a synapse we show here that, in fact, the statistical properties of a presynaptic conditioning signal could change the probability to induce LTP and/or LTD, suggesting a new and faster operating mode for a synapse.

Animals↗
PubMed1999

Long-term potentiation and depression induced by a stochastic conditioning of a model synapse.

Protracted presynaptic activity can induce long-term potentiation (LTP) or long-term depression (LTD) of the synaptic strength. However, virtually all the experiments testing how LTP and LTD depend on the conditioning input are carried out with trains of stimuli at constant frequencies, whereas neurons in vivo most likely experience a stochastic variation of interstimulus intervals. We used a computational model of synaptic transmission to test if and to what extent the stochastic fluctuations of an input signal could alter the probability to change the state of a synapse. We found that, even if the mean stimulation frequency was maintained constant, the probability to induce LTD and LTP could be a function of the temporal variation of the input activity. This mechanism, which depends only on the statistical properties of the input and not on the onset of additional biochemical mechanisms, is not usually considered in the experiments, but it could have an important role to determine the amount of LTP/LTD induction in vivo. In response to a change in the distribution of the interstimulus intervals, as measured by the coefficient of variation, a synapse could be easily adapted to inputs that might require immediate attention, with a shift of the input thresholds required to elicit LTD or LTP, which are restored to their initial conditions as soon as the input pattern returns to the original temporal distribution.

Long-Term Potentiation↗
PubMed1999

Clinical features and oesophageal motility in patients with tight fundoplication.

OBJECTIVE: Tight fundoplication is a well known complication of surgery for gastroesophageal reflux. We have noted, in clinical experience, that some patients operated for gastro-oesophageal reflux develop pharyngo-oesophageal dysphagia. This study was undertaken to elucidate, by comparing motility data in patients with and without tight fundoplication, the pathophysiologic characteristics of the swallowing mechanism and to clarify the cause of dysphagia in these patients. METHODS: Sixteen patients with postoperative persistent dysphagia following a fundoplication have been studied, of those 10 presented a lower oesophageal sphincter resting pressure above or equal to 30 mmHg (group A). Clinical work-up included a questionnaire, oendoscopy, manometry and barium meal or video-roentgenography. Oesophageal manometry was performed using a slow pull through technique while the stationary pull through technique was used for the pharyngo-oesophageal segment. The following parameters were evaluated: (a) amplitude of pharyngeal contraction; (b) upper oesophageal sphincter resting pressure; (c) amplitude of upper oesophageal sphincter contraction; (d) amplitude of oesophageal contraction; (e) lower oesophageal sphincter resting pressure. The results were compared to those of 21 patients who had a fundoplication with normal lower oesophageal sphincter pressure (group B). RESULTS: in group A there were three males and seven females, with a mean age of 51 years (ranging from 28 to 60 years). Previous operations were Nissen in two and Nissen Rossetti in eight patients. Three out of 10 patients of group A presented pharyngo-oesophageal dysphagia. Mean lower oesophageal sphincter 36 versus 21 mmHg and upper oesophageal sphincter 86 versus 42 mmHg resting pressure, pharyngeal 147 versus 76 mmHg and oesophageal amplitude, upper oesophageal contraction 251 versus 103 mmHg were significantly higher in patients of group A versus group B. An increased number of repetitive contractions was also found in group A. The presence of a strong correlation was demonstrated between the pharyngeal amplitude and the closing tone of the upper oesophageal sphincter (R2 0.742 and R2 0.739) in both groups. CONCLUSION: Tight fundoplication is, in our experience, always associated with total fundoplication. The appearance of pharyngo-oesophageal dysphagia in the postoperative period in patients operated on to correct gastroesophageal reflux using a total fundoplication, should not be under-estimated because it suggests an obstruction of the distal oesophagus.

Adult↗
PubMed1998

Neuropsychological outcome of operated cerebral aneurysms: prognostic factors on 148 patients.

OBJECTIVES: To analyse prognostic factors in patients operated upon for cerebral aneurysms. A previous investigation by our group showed that patients operated later than 10 days after bleeding have a worse neuropsychological prognosis, but the number of patients operated upon within 3 days was not sufficient. Here, a new sample of patients with early surgery is included in the analyses. MATERIAL AND METHODS: Patients numbered 148 (65 with ACoA, 39 with MCA, and 44 with PCoA aneurysms): 56 were operated within 3 days, 44 within 4-10 days, and 48 after at least 10 days from bleeding. A standardized battery of 13 neuropsychological tests was adopted: we considered both the number of defective scores and the average performance. RESULTS: Patients operated later than 10 days after bleeding had a worse prognosis than the 2 groups with early and intermediate surgery, which were not different. Aneurysm site was not relevant. Old age and low education were associated with a worse prognosis. Hunt and Hess scores at operation and post operation were also predictive of the outcome. CONCLUSION: On the whole, patients operated upon later than 10 days after bleeding have a less favourable prognosis than those with earlier operation timing.

Adolescent↗
PubMed1998

Pedunculated intraluminal oesophageal fibrolipoma. A case report.

Benign tumours of the oesophagus are rare. A patient with a pedunculated intraluminal tumour presented with dysphagia of recent onset and the tumour resected at open operation and histology was confirmed as a benign vascular fibrolipoma. We discuss the management and review the relevant literature.

Esophageal Neoplasms↗
PubMed1997

Possible roles of retrograde messengers on LTP, LTD, and associative memory.

There are still no clear biophysical models for Associative Long-Term Potentiation (LTP) and Depression (LTD) in the hippocampus, where two populations of synapses targeted to the same receptive field are involved. Here we propose a model that allows an interpretation of the experiments in terms of the molecular processes that may be involved in associative memory. The model suggests that retrograde messengers could have a critical role in the induction and maintenance of associative LTP and LTD, by controlling the coupling between the two populations of synapses.

Electric Stimulation↗
PubMed1996

Modeling the attenuation and failure of action potentials in the dendrites of hippocampal neurons.

We modeled two different mechanisms, a shunting conductance and a slow sodium inactivation, to test whether they could modulate the active propagation of a train of action potentials in a dendritic tree. Computer simulations, using a compartmental model of a pyramidal neuron, suggest that each of these two mechanisms could account for the activity-dependent attenuation and failure of the action potentials in the dendrites during the train. Each mechanism is shown to be in good qualitative agreement with experimental findings on somatic or dendritic stimulation and on the effects of hyperpolarization. The conditions under which branch point failures can be observed, and a few experimentally testable predictions, are presented and discussed.

Action Potentials↗
PubMed1996

Pharyngo-oesophageal dysphagia: surgery based on clinical and manometric data.

High or pharyngo-oesophageal dysphagia (PD) is defined as difficulty in initiating the act of swallowing within 1s. It involves the mechanisms controlling the tongue, pharynx and upper oesophageal sphincter (UOS) and is associated with a wide variety of local, neurologic and muscular disorders, and can also occur after surgery in the area and in response to gastro-oesophageal reflux (GOR). Our study aims at defining the criteria for surgery in PD and to evaluate the clinical results of such treatment. Twenty-three patients who underwent surgery were evaluated with pharyngo-oesophageal motility and ambulatory 24-hr pH-metry. The following parameters were measured: 1) pharyngeal contraction amplitude, 2) duration, 3) repetitive pharyngeal contractions, 4) UOS tone, 5) percentage of UOS relaxation, 6) duration of relaxation, 7) UOS closing pressure, 8) UOS closing duration, 9) co-ordination of UOS closing pressure and upper oesophageal (UO) contractions. Preoperative manometry showed a variety of abnormalities in several of the parameters, such as prolonged pharyngeal contraction ("spasm"), unco-ordinated pharyngeal contractions and UOS relaxation, low amplitude pharyngeal contractions, unco-ordinated UOS closing tone and UO contractions and hypotonic UO. Surgery was directed at the specific abnormality in each patient taking into consideration the presence or absence of GOR. Seventeen patients (74%) had excellent results. Three other patients (13%), who had improved swallowing but who continued to have GOR complicated by some oesophageal dysmotility, oesophagitis and an oesophageal web, underwent subsequent anti-reflux surgery with relief of symptoms. In conclusion, pharyngo-oesophageal motility measurement is mandatory in PD, especially when a diverticulum is absent. Cricopharyngeal myotomy with or without diverticulectomy as indicated produces excellent results. Associated oesophageal problems have to be dealt with appropriately.

Adult↗
PubMed1996

Postoperative pain in neurosurgery: a pilot study in brain surgery.

The incidence, magnitude, and duration of acute pain experienced by neurosurgical patients after various brain operations are not precisely known, because of a lack of well-designed clinical and epidemiological studies. We assessed these important pain variables in 37 consecutive patients who underwent various brain neurosurgical procedures. Postoperative pain was more common than generally assumed (60%). In two-thirds of the patients with postoperative pain, the intensity was moderate to severe. Pain most frequently occurred within the first 48 hours after surgery, but a significant number of patients endured pain for longer periods. Pain was predominantly superficial (86%), suggesting somatic rather than visceral origin and possibly involving pericranial muscles and soft tissues. Subtemporal and suboccipital surgical routes yielded the highest incidence of postoperative pain. Age and sex were significantly associated with the onset of pain, with female and younger patients reporting higher percentages of postoperative pain. Psychological Minnesota Multiphasic Personality Inventory profiles of patients with and without pain significantly differed on the Hypochondriasis scale, with patients without pain scoring unexpectedly higher than patients with pain. It is possible that hypochondriasis serves as a defense mechanism against pain, at least in some patients. Results of this pilot study indicate that postoperative pain after brain surgery is an important, although neglected, clinical problem, that deserves greater attention by surgical teams, to provide better and more appropriate treatment.

Adult↗
PubMed1996

Villous adenocarcinoma of the duodenum invading the ampulla of Vater case report and review of literature.

We report a case of villous adenocarcinoma of duodenum arising from the ampulla of Vater with a review of the literature. Although preoperative endoscopic biopsies were performed, no malignancy was identified. Because of the pathological uncertainty we decided to perform a pylorus-preserving pancreatoduodenectomy. Microscopic examination demonstrated glandular dysplasia with aspects of villous adenoma and well differentiated adenocarcinoma. We conclude that both in malignant cases and in cases with uncertain diagnosis a pylorus-preserving pancreatoduodenectomy is the best surgical treatment because it results in better 5 year survival.

Adenocarcinoma↗
PubMed1995

Input-output relations in the entorhinal-hippocampal-entorhinal loop: entorhinal cortex and dentate gyrus.

The pattern of impulse transfer along the entorhinal-hippocampal-entorhinal loop has been analyzed in the guinea pig by field potential analysis. The loop was driven by impulse volleys conducted by presubicular commissural fibers, directly stimulated in the dorsal psalterium, which monosynaptically activated perforant path neurons in the medial entorhinal cortex. Perforant path volleys activated in sequence the dentate gyrus, field CA3, field CA1, subiculum, and entorhinal cortex. Input-output curves were reconstructed from responses simultaneously recorded from different stations along the loop. The entorhinal response to the presubicular volley was found to increase gradually with respect to its input. The population excitatory postsynaptic potential (EPSP) of the dentate gyrus granule cells had a similar behavior. By contrast, the input-output relation between the granule cell population spike and population EPSP was described by a very sleep sigmoid curve. The population spike of CA3 and CA1 pyramidal neurons as well as the response evoked in the entorhinal cortex by the hippocampal output had slightly higher threshold than the granule cell population spike and, like the latter, abruptly reached maximum amplitude. These findings show that the entorhinal-hippocampal-entorhinal loop transforms a linear input in a non-linear, almost all-or-none output and that the dentate gyrus is the critical site where the transformation occurs. Beyond the dentate gyrus, the loop appears very permeant to impulse traffic.

Afferent Pathways↗
PubMed1995

A model for long-term potentiation and depression.

A computational model of long-term potentiation (LTP) and long-term depression (LTD) in the hippocampus is presented. The model assumes the existence of retrograde signals, is in good agreement with several experimental data on LTP, LTD, and their pharmacological manipulations, and shows how a simple kinetic scheme can capture the essential characteristics of the processes involved in LTP and LTD. We propose that LTP and LTD could be two different but conceptually similar processes, induced by the same class of retrograde signals, and maintained by two distinct mechanisms. An interpretation of a number of experiments in terms of the molecular processes involved in LTP and LTD induction and maintenance, and the roles of a retrograde signal are presented and discussed.

Animals↗
PubMed1995

Diffuse colonic lipomatosis with giant hypertrophy of the epiploic appendices and diverticulosis of the colon. Report of a case and review of the literature.

PURPOSE: A case of diffuse colonic lipomatosis, dolichosigmoid, hypertrophy of the epiploic appendices and diverticulosis of the colon producing constipation, recurrent sub-occlusive episodes with diarrhea and vomiting, and weight loss is reported. METHODS: Careful preoperative assessment of clinical, radiologic, and endoscopic findings suggested the diagnosis. RESULTS: A total colectomy, followed by a lateroterminal ileoproctostomy, gave complete relief from symptoms. CONCLUSIONS: Of the 12 cases of colonic lipomatosis previously reported, only 2 have isolated involvement of the entire organ, but they do not present lipomatosis of the epiploic appendices.

Adult↗