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Biomedical subjects

F Alessandrini

Publications and source records attributed to F Alessandrini.

At least 55 records · Page 3Linked to original sources
PubMed1996

Improvement of pulmonary graft after storage for twenty-four hours by in vivo administration of lazaroid U74389G: functional and morphologic analysis.

BACKGROUND: We examined the effects of in vivo administration of a potent inhibitor of iron-dependent lipid peroxidation, lazaroid U74389G, on lung preservation. METHODS: Lungs isolated from Sprague-Dawley rats (n = 23) were either immediately reperfused after removal (control, n = 8) for 2 hours by means of an isolated, pulsatile blood perfusion system or reperfused after cold storage (4 degrees C) for 24 hours in the University of Wisconsin solution with (n = 7) or without (n = 8) lazaroid. The lazaroid group had in vivo infusion of lazaroid U74389G (6 mg/kg) before lung harvest plus addition to the perfusate (50 mu mol/L) at the onset of reperfusion. Routine aerodynamics, hemodynamics, and blood gases were assessed during the perfusion period. Lipid peroxidation in the lung tissue was assayed with the thiobarbituric acid-reactive product, malondialdehyde. Histologic evaluation was performed with light microscopic and transmission electron microscopic analyses. RESULTS: All lungs in the University of Wisconsin solution group (24-hour storage without lazaroid) failed within 1 hour of reperfusion. Lungs in control and University of Wisconsin solution + lazaroid group survived the 2-hour perfusion period. University of Wisconsin solution + lazaroid group showed significantly better arterial oxygen tension values relative to those in the University of Wisconsin solution group (control, 85.2 +/- 1.9; University of Wisconsin solution, 53.9 +/- 3.2 [p < 0.05 versus control group and University of Wisconsin solution + lazaroid]; University of Wisconsin solution + lazaroid, 74.8 +/- 1.4; arterial oxygen tension (mm Hg) at 30 minutes). Lipid peroxide in University of Wisconsin solution + lazaroid group was significantly lower than that of the University of Wisconsin solution group (65.0 +/- 5.0 versus 495 +/- 105 nmol malondialdehyde/gm wet lung tissue; p < 0.01). Transmission electron microscopic analysis showed that University of Wisconsin solution + lazaroid group significantly attenuated lung damage when compared with University of Wisconsin solution group. CONCLUSION: Administration of lazaroids in vivo before organ harvest and in situ at the onset of the reperfusion enhances lung preservation in this model.

Animals↗
PubMed1995

Enhancement of extended lung preservation with a vasoactive intestinal peptide-enriched University of Wisconsin solution.

Vasoactive intestinal peptide (VIP) is a known pulmonary and bronchial vasodilator as well as an oxygen free radical scavenger. Since its effect as an additive to University of Wisconsin (UW) solution for lung preservation has been shown previously, the aim of this study was to determine the ability of VIP to improve lung preservation followed by reperfusion. Four groups of excised Sprague-Dawley rat lungs (n = 24) were studied using an isolated blood perfused working lung model. The first 3 groups of lungs were flushed and stored in UW solution at 4 degrees C for: (1) 4 hr, (2) 18 hr, and (3) 24 hr. Group 4 lungs were flushed with UW solution + VIP (1 microgram/ml) and stored in UW solution + VIP (0.5 microgram/ml) for 24 hr. After preservation, the lungs were reperfused to evaluate their functions for 2 hr or until lung failure occurred (arterial oxygen saturation less than 90% and/or appearance of bronchial fluid in the bronchial cannula). In the lungs stored in UW solution for 24 hr, failure occurred after 10 min of reperfusion and all functions were significantly altered. The addition of VIP to UW solution maintained the functional capacity of the lungs, recorded by lung resistance, lung compliance, elastic work, flow resistive work, shunt fraction, and blood oxygen tension. No statistical difference in these parameters other than shunt fraction was found when the VIP group was compared with the group preserved for 4 hr in UW solution. We conclude that lung preservation can be extended to 24 hr with the maintenance of lung functional capacity if VIP is added to UW solution.

Adenosine↗
PubMed1995

Impact of initial flush potassium concentration on the adequacy of lung preservation.

The effects of initial lung flushing with intracellular and extracellular fluid type solutions were studied in lungs stored with the University of Wisconsin solution. Excised Sprague-Dawley rat lungs (n = 39) were flushed first with one of the following solutions: (1) the University of Wisconsin solution (K+ = 140 mmol/L), (2) modified (low potassium) University of Wisconsin solution (K+ = 20 mmol/L), (3) phosphate buffered saline solution (K+ = 3.9 mmol/L), (4) modified low-potassium phosphate-buffered saline solution (K+ = 20 mmol/L), (5) modified high-potassium phosphate-buffered saline solution (K+ = 40 mmol/L), and (6) Euro-Collins solution (K+ = 115 mmol/L) followed by secondary flush with storage solution and cold (4 degrees C) storage in University of Wisconsin solution for 24 hours. The lungs were then reperfused in the isolated, pulsatile, blood-perfused working lung system for 2 hours or until lung failure. Blood gas analysis and shunt fraction, aerodynamic parameters (airway resistance, lung compliance, elastic work, and flow resistive work), and total pulmonary vascular resistance were measured throughout the perfusion period. The mean oxygen tensions (in millimeters of mercury) at 30 minutes after the onset of reperfusion for University of Wisconsin solution, modified University of Wisconsin solution, phosphate-buffered saline solution, modified phosphate-buffered saline solutions (20 and 40 mmol/L), and Euro-Collins solution were 56.1 +/- 4.2, 72.7 +/- 9.1, 87.7 +/- 6.9 (p < 0.01 versus University of Wisconsin solution; p < 0.01 versus Euro-Collins solution), 86.0 +/- 9.6 (p < 0.01 versus University of Wisconsin solution; p < 0.01 versus Euro-Collins solution), 87.9 +/- 7.7 (p < 0.01 versus University of Wisconsin solution; p < 0.01 versus Euro-Collins solution), and 53.5 +/- 6.0, respectively. All aerodynamic parameters in the lungs flushed with extracellular fluid type solutions were superior to those flushed with intracellular fluid type solutions. We conclude that the efficacy of initial flushing was essential for successful lung preservation and that extracellular fluid type solutions were superior to intracellular fluid type solutions, at least for flushing the lung before storage with University of Wisconsin solution. Potassium concentration in flushing solution should be 20 mmol/L or less to obtain appropriate flushing and subsequent adequate distribution of the storage solution.

Adenosine↗
PubMed1995

Stereotactic radiosurgery of uveal melanomas: preliminary results with Gamma Knife treatment.

Twelve cases of uveal melanoma (T3N0M0:11 patients, T4N0M0:1 patient) treated with Gamma Knife stereotactic radiosurgery are reported. Our protocol includes preoperative ocular and systemic assessments with complete ocular examination, ophthalmoscopy, fundus photography, fluorangiography, standardized echography, CT and MRI, chest X-rays, liver echography and blood tests. The follow-up program is mainly based on echographic evaluation of tumor thickness and size. The procedures include fixation of the eye, application of the stereotactic Leksell frame G, CT/MRI localization of the melanoma, dose planning and treatment with the Gamma Knife (B type). A mean surface dose of 55 +/- 10 Gy was administered at the 60-90% isodose curve using 4- to 14-mm collimators and a number of shots ranging from 1 to 6. A significant reduction (10-41%) in echographic thickness of the tumor was shown in 6 cases with a follow-up of 3-12 months. In 4 patients, the tumor size was still unchanged after 1-10 months. The single high-dose radiation delivered to the target and the high spatial accuracy are the main advantages of stereotactic radiosurgery for the treatment of posterior uveal melanomas. A longer followup is needed to further validate this new application of Gamma Knife radiosurgery.

Adult↗
PubMed1995

Quality assessment of magnetic resonance stereotactic localization for Gamma Knife radiosurgery.

Artifacts in magnetic resonance imaging (MRI) may lead to anatomical distortion and inaccurate stereotactic coordinates. A special phantom for MRI and computed tomography (CT) was built to test the quality and precision of the two neuroradiological procedures. The phantom is fixed with the Leksell frame, and it has 15 orthogonal markers visible by CT and MRI techniques. The coordinates of the markers were calculated first on the CT scans and then on MR images. Two groups of different distortions were analysed: artifacts depending on the frame and its components and artifacts depending on the MR unit and image characteristics. A good target-coordinate correlation was found between CT and MRI in the axial plane, while in the coronal plane there was always a small error. This error is not constant, but changes from test to test, consequently it is hard to reform the image.

Artifacts↗
PubMed1995

Immunohistochemical evidence for sympathetic denervation and reinnervation after necrotic injury in rat myocardium.

To study the short and long term effects of myocardial injury on sympathetic nerve fibers, a necrotizing lesion was performed on the diaphragmatic side of rat myocardium by freeze-thawing. Animals were sacrificed at 2, 6, 18, 28 and 105 days after the surgical procedure and paraffin-embedded hearts were subjected to peroxidase immunohistochemistry. According to previous studies cardiac nerves were visualized by staining their surrounding Schwann cells with an anti-S100 protein antibody. Catecholaminergic axons were specifically identified by an anti-tyrosine hydroxylase antibody. No S-100 positive structures were found in 2-day lesions (denervation). Starting from day 6,S-100 positive structures became progressively more evident (reinnervation) and persisted up to day 105. Many of these newly formed nerve fibers were positive for tyrosine hydroxylase, indicating that a necrotic injury of rat myocardium causes a disappearance of sympathetic innervation which is followed by a phase of sympathetic reinnervation.

Animals↗
PubMed1995

Cavernous malformation of the internal auditory canal. A case report.

A 51 year-old male, complaining of progressive left-sided hearing loss, tinnitus, and unsteady gait, underwent surgery with a probable diagnosis of intracanalicular acoustic neuroma, based on neurological, neurotologic, Computed Tomography (CT), and Magnetic Resonance Imaging (MRI) findings. During surgery, the Internal Auditory Canal (IAC) was opened and a reddish-colored, soft, vascular lesion was found within the VII and VIII cranial nerve complex. The lesion, which resulted to be a cavernous malformation, was removed without any postoperative deficits. This report stresses the diagnostic difficulty to differentiate preoperatively the more frequent acoustic neuromas from other lesions that may develop within the IAC.

Cavernous Sinus↗
PubMed1994

Experimental researches on heart and lung preservation.

The purpose of these experimental researches was to study the physiopathology of heart and lung preservation. The current problem of the paucity of lung and heart-lung donors can be solved either by retrieving the organs from cadavers or by increasing the time of preservation. Since the lung is more susceptible to ischemic injury if compared to the heart, we focused our studies on lung preservation techniques. Our results show that lung flushing prior to preservation is very important and the density and the potassium content of the solutions used for this purpose have to be chosen carefully. The addition of a surfactant precursor to the UW preservation solution maintained the pulmonary surfactant for at least 4 hrs of cold storage, but it failed to preserve lung ultrastructure for more than 4 hrs. The UW solution preserved heart ultrastructure for at least 6 hrs of cold-storage. Heat shock to induce the synthesis of heat shock proteins and catalse but failed to protect the heart from ischemia-reperfusion injury. The addition of vasoactive intestinal peptide (VIP) to the preservation solution maintained lung morphology and function upon 24 hrs of preservation and reperfusion and other authors showed that VIP protects the heart from ischemia-reperfusion injury. We are planning further investigations aiming to improve and extend the time of heart and lung preservation.

Animals↗
PubMed1993

Vasoactive intestinal peptide enhances lung preservation.

The outcome of lung transplantation is often dependent on the quality of the donor lungs. To explore a way to improve lung preservation, vasoactive intestinal peptide (VIP) was added to pneumoplegic solutions. The 4 solutions tested were Krebs solution, Krebs solution with VIP, University of Wisconsin solution, and the University of Wisconsin solution with VIP. The lungs of 8 male Sprague-Dawley rats were flushed and stored in these solutions for 24 hr. At regular intervals, tissue was sampled and examined by light, scanning, and transmission electron microscopy. Casts of the vasculature were made after 4 hr and viewed by a scanning electron microscope. Lungs appeared well preserved by light microscopy at all intervals. Although inflammatory cells around arteries, arterial constriction, bronchiolar epithelial detachment, peribronchiolar edema, and alveolar size inhomogeneity were greater with time, there was no significant difference among the 4 groups by light microscopy. Scanning microscopy of tissue at 24 hr confirmed the information found on light microscopy but did not allow separation of the groups. The vascular casts showed that edema around large vessels was less in the lungs treated with VIP (P < 0.01). Transmission electron microscopy showed that lungs stored in the solutions with VIP had significantly more normal-shaped mitochondria, less mitochondrial edema, less distortion of mitochondrial cristae, thinner basal lamina, and less aggregation of nuclear chromatin at most intervals sampled after 4 hr. We conclude that VIP added to certain pneumoplegic solutions improves the ultrastructure of rat lung stored in the cold for up to 24 hr. VIP may be an important additive to pneumoplegic solutions to improve preservation of lung before transplantation.

Adenosine↗
PubMed1993

[Results of surgical treatment in supraventricular tachycardias].

From May 1989 to May 1992, 44 patients (mean age 41 years, range 15-66) underwent surgery for supraventricular tachycardias: in 35 patients with atrioventricular reentrant tachycardia or atrial fibrillation associated with accessory pathway and refractory to medical treatment, the epicardial approach was used; in 8 with atrioventricular nodal reentrant tachycardia, a perinodal cryosurgery of the atrioventricular node was used, and in 1 patient with atrial flutter a cryosurgical ablation around the orifice of the coronary sinus and surrounding tissues was performed. All 38 accessory pathways were successfully ablated in 35 patients and no recurrences of delta wave or tachycardia were observed during a mean follow-up of 17 +/- 10 months. Atrial perforation during surgery and pericarditis were the only complications observed. All 8 patients with atrioventricular nodal reentrant tachycardia were successfully treated: in 2 patients dual pathways persisted after surgery but tachycardia was no longer inducible. No recurrences were observed during a mean follow-up of 15 +/- 4 months. Since surgery (15 months), the patient with atrial flutter has been free of recurrent episodes of atrial flutter. In conclusion, surgical treatment of supraventricular tachycardias is highly successful, with no mortality and very low morbidity. Should transcatheter ablation fail, surgery should be the treatment of choice in patients with frequent and symptomatic supraventricular tachycardias.

Adolescent↗
PubMed1991

Surgical treatment of cardiac arrhythmias.

This report describes 20 consecutive patients who underwent surgical procedures for treatment of cardiac arrhythmias. 16 patients have been operated for WPW syndrome, always using the epicardial approach, without extracorporeal circulation. Three patients underwent surgery for atrio-ventricular nodal reentrant tachycardia, using a discrete perinodal cryotreatment, during normothermic extracorporeal circulation. In one case we used cryoablation of the atrial myocardium below the coronary sinus to treat atrial flutter. This operation was performed under normothermic extracorporeal circulation. In our observations, there was no early or late death; postoperative complications developed in 1 patient (5%) due to pericarditis. Ablation of the AP was completely successful in all the cases (100%) operated for WPW as well as for AVNRT syndromes and atrial flutter.

Arrhythmias, Cardiac↗
PubMed1991

Comparison between two versus three patches single pulse shock defibrillation in pigs.

The aim of the study was to test the hypothesis that defibrillation with a single pulse shock can be obtained at lower energy using three epicardial patches configuration (one cathode and two anodes) instead of the conventional two patches. The total surface area of the two- and three-patches configuration was the same (10 cm2 vs 9.9 cm2). Epicardial spatial configuration was planned by using a computerized heart model. In ten anesthetized open-chest pigs, ventricular fibrillation was induced by using AC current through the mesh plaque epicardial custom-designed electrodes, and the minimum energy requirement for defibrillation was determined 15 seconds after the onset of stable ventricular fibrillation. Results were as follows (mean +/- standard deviation): Defibrillation Threshold 16 +/- 9 J 9 +/- 5 J P less than 0.01 CONCLUSIONS: three epicardial patches configuration significantly reduces energy requirements for defibrillation compared with two patches when single pulse shock is used.

Animals↗
PubMed1991

[Right accessory pathway simulating a nodo-ventricular pathway: an electrophysiologic study and intraoperative mapping].

We report a case of a patient with episodes of wide QRS tachycardia and syncope. During the electrophysiologic study, a wide QRS tachycardia (200 b/m) with left bundle branch block morphology was reproducibly induced by incremental atrial pacing with progressive shortening of the HV interval and lengthening of the AV interval, suggesting the presence of a nodoventricular accessory pathway (Mahaim fiber). The intraoperative mapping performed during tachycardia showed the earliest ventricular activation to be over the right antero-lateral AV groove, different from the usual epicardial activation previously described. According to the earliest epicardial breakthrough point, we performed an epicardial AV fat pad dissection which produced irreversible disappearance of preexcitation, confirmed at the postoperative electrophysiologic study. No recurrence of tachycardia was observed during a follow-up of 11 months. This case further confirms previous data that the "so-called" Mahaim fibers could be a right accessory pathway with decremental properties.

Adult↗
PubMed1990

Intravenous propafenone reduces energy requirements for defibrillation in pigs.

The effect of antiarrhythmic drugs on defibrillation threshold have become an important issue with the increasing use of the automatic implantable cardioverter defibrillator (AICD). In several reports antiarrhythmic therapy has been found to affect the energy required for defibrillation; the present study examined the effects of intravenous propafenone on defibrillation threshold in open chest, anesthetized pigs. Twenty health pigs were studied; 10 pigs free from any drugs (Group 1) and 10 pigs after a constant iv infusion of 0.04 mg/kg/min of propafenone (Group 2). Defibrillation threshold was 21 +/- 5, 20 +/- 5, 21 +/- 6, 19 +/- 4 and 19 +/- 6 J in Group 1 and 20 +/- 7, 18 +/- 9, 15 +/- 5, 14 +/- 7, 9 +/- 6 J in Group 2, respectively at 20, 40, 60, 80 min (p value respectively NS, NS, less than 0.05, less than 0.01, less than 0.001). We conclude that intravenous propafenone reduces the energy requirements for defibrillation in experimental animals.

Animals↗