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Biomedical subjects

S Nazari

Publications and source records attributed to S Nazari.

At least 19 recordsLinked to original sources
PubMed1998

[Physiopathology of pulmonary emphysema. Analysis of structural changes in the pulmonary architecture and therapeutic implications].

In the pulmonary emphysema a serious respiratory inadequacy can result from the impossibility of the thoracic cage and of the diaphragm to expand beyond a maximum limit, before that a significnat part of pulmonary parenchyma has been destroyed by the pathogenic process. The resection of part of the lung, selectively in the areas where the emphysematous injuries are more pronounced, brings again the ventilation of the residual pulmonary parenchyma toward more physiological expansion values of the thoracic cage and diaphragm, thus decreasing the respiratory work, improving the ventilation mechanics and the bronchial obstruction. The time duration of the improvement achieved with the lung volume reduction is still to be demonstrated. A clinical and therapeutic analysis of this pathology is carried out.

Airway Obstruction↗
PubMed1998

[The surgical physiopathology of essential pulmonary emphysema and volume-reduction intervention].

The breaking of the interalveolar septa represents, in the pathogenetic mechanism of emphysema, a final event, common to the different etiologic agents. This elementary injury causes a series of consequences, essentially of mechanic-structural type (intrapulmonary aerial spaces-confining parenchyma collapse, bronchial obstruction, dead space augmentation) on the thin and articulate bronchoalveolar architecture, whose final rearrangement determines, at least in part, the clinical picture. In short, the break of alveolar septa involves the formation of intraparenchymal aerial spaces with collapse of the confining lung; the compensatory mechanism to this situation, involves the hyperexpansion of the thoracic cage and flattening of the diaphragm, with the aim of allowing ventilation of the healthy residual parenchyma. Because of the finite capability of expansion of the thoracic cage and of the diaphragm in respect to the theoretical capability of the lung of large intraparenchymal aerial spaces formation, it is easy to imagine that emphysema can cause a serious functional respiratory deficit even before a significant quantity of pulmonary parenchyma is destroyed by the pathogenic process. It may then be hypothesized that a simple reduction of the volume of the lung, even sacrificing a part of "working" parenchyma, might allow the residual lung to come back to a normal ventilation, wholly ameliorating the respiratory exchanges. The clinically more remarkable consequence of lung volume reduction is the amelioration of ventilation mechanics with a decreased respiratory work due to the shift of the tidal volume toward values less proximal to the maximal expandability of the thoracic wall and of the diaphragm. On the other end, it is possible to anticipate an equally significant effect on bronchial obstruction, due to the more favorable matching of the compliance of the thoracic wall and that of the lung. LVRS has significant effect on the TV sharing ratio between emphysematous spaces and residual healthy parenchyma; the hyperexpansion of the residual lung in fact causes the distension of the emphysematous spaces, continuing in the natural compensatory mechanism of the emphysema. The decreased ventilation and thus re-breathing of the residual emphysematous spaces, together with the improved ventilation may ameliorate hypercapnia. Obviously no direct effects can be expected from LVRS on the conditions of the alveolar membrane and thus on gas diffusion capacity through it. The time duration of the amelioration achieved with the lung volume reduction is still to be demonstrated.

Bronchi↗
PubMed1997

Prosthesis for aortic arch substitution.

BACKGROUND: The risk of neurologic complications in aortic arch prosthetic substitution is directly related to the duration of the circulatory arrest. The purpose of this article is to report the experiments on animals of a device for simplifying and quickening the vascular anastomosis in aortic arch substitution. METHODS: The device consists of expandable loops of stainless steel wire, sewn to the proximal end of a Dacron prosthesis. An actuating removable guide allows the stainless steel wire loops to be expanded and tightened, in such a way that the prosthesis diameter is varied, while maintaining a regular cylindric shape. The prosthesis end is then transformed into a rigid cylindrical ring, approximately half the maximal diameter in length, with a variable and controllable diameter. A composite graft was prepared, fitted with the expandable device at the distal end of the main prosthesis as well as at each end of the branches for the supraaortic trunks. Cardiopulmonary bypass was established by cannulation of the right atrium and left iliac artery. The prosthesis was positioned very easily and quickly during a brief hypothermic circulatory arrest; ascending aorta anastomosis was carried out by the standard technique after central nervous system reperfusion was resumed. Acute experiments were carried out in 5 swine. RESULTS: Four of 5 animals survived the procedure without detectable neurologic sequelae. At sacrifice the prosthesis was found to be properly sited without lumen distortion or thrombosis. CONCLUSIONS: The main advantages of this device and modality of arch substitution in a clinical setting would include drastic reduction of the circulatory arrest time, easy and reliable hemostasis of the anastomosis line, and accurate and firm approximation of the dissection layers in case of dissecting aneurysms.

Animals↗
PubMed1996

Aortic wall structural strengthening by intraluminal net prosthesis to arrest aneurysm progression and to prevent dissection and rupture.

The major limitation implicit in the endovascular procedures for aortic prosthetic substitution is that they cannot be used in those tracts of the aorta where important collateral branches originate (aortic arch, thoraco-abdominal tract, upper abdominal), that would be occluded by the prosthesis. In order to overcome this limitation we hypothesized the endovascular positioning of a prosthesis in the form of a wide mesh network that would be gradually and spontaneously covered by new intima and included in the aortic wall. The fabric framework linked to the aortic wall would then condition its significant, regular and uniform mechanical strengthening that fractionates and partially absorbs the centrifuge pulsatile stress of the bloodstream. The purpose of this paper is to report the results of the insertion of a braided Prolene net prosthesis in the first 7 cm of the descending aorta of ten swine. The animals were killed after 6 weeks, the substituted segment removed and aortic wall compliance measured under standardized conditions. The prosthesis was found entirely covered by new intima, well embodied in the aortic wall. The intercostal collateral included in the substituted segment was patent, as proved by bubble formation during underwater insufflation. Compliance of the prosthesis segment was significantly lower than that of the adjacent descending aorta. Histology showed a regular net prosthesis inclusion deep in the neo-intima layer. Present results indicate the technical feasibility of the procedure, achieving significant aortic wall strengthening without affecting the collateral (intercostal) circulation.

Aortic Dissection↗
PubMed1996

Expandable prosthesis for sutureless anastomosis in thoracic aorta prosthetic substitution.

OBJECTIVE: Most complications of descending aorta prosthetic substitution seem mainly to be related directly (ischemia to distal organs, i.e. liver, kidney, spinal cord) or indirectly (extracorporeal circulation or shunts and systemic heparinization complications) to the duration of blood flow interruption. the purpose of this study is to report the results of animal experimentation of a new device for sutureless prosthetic substitution of the descending thoracic aorta, with a very short cross-clamping phase. METHODS: The device consists of expandable loops of stainless steel wires, sewn to the proximal end of a Dacron prosthesis. The stainless steel wire loops can be expanded and tightened by activating a removable guide in such a way that the prosthesis varies its diameter, while maintaining a regular cylindrical shape. The device was prepared in two different configurations, one for long segments (expandable prosthesis end) and the other to be used for very short segments or as an anastomotic ring between prosthetic or vascular stumps (quick anastomotic ring). The expandable prosthesis end was tested in swine experiments by performing the prosthetic substitution of the first 10 cm of descending cross-clamped aorta, the prosthesis being fixed with the device both at the proximal and the distal ends (six experiments). All animals survived the procedure, that was accomplished with a very short cross-clamping time. The quick anastomotic ring was used to anastomose two prosthesis ends, at the middle of the prosthetic segment used for descending aorta substitution (two swine), to perform the distal anastomosis in the same model of descending aorta substitution (one swine) and simply to re-anastomose a subtotally transected descending aorta (one swine). RESULTS: The present experience proved the reliability of the device to carry out a sutureless, accurate, simple and quick anastomosis. Its advantage over an intraluminal ringed prosthesis is much easier insertion of the retracted wired end into the vascular stumps, thus allowing for a prosthetic diameter appropriate to the substituted vessel. CONCLUSIONS: The reduced cross-clamping feature of the device would suggest its use mainly in thoracic aorta prosthetic substitution for the prevention of ischemic damage to distal organs; it can also be used to advantage wherever an end-to-end vascular or prosthetic anastomosis is indicated, providing an accurate, stented anastomosis.

Anastomosis, Surgical↗
PubMed1996

Potentials of liposomes in diagnosis and treatment of pulmonary metastases: an experimental study in the rat.

OBJECTIVE: The ultimate goal of the therapy of lung metastases is to destroy all malignant cells while sparing normal ones. Liposomes represent a novel approach for the selective transport of tracers and therapeutic agents to cancer cells because of their flexibility, low toxicity, wide range of possible variants, simplicity to make, and because agents can be entrapped in them in their native states in large amounts. We have studied the biodistribution of "Stealth" liposomes in the experimental model of lung metastases in the rat. METHODS: The secondaries were induced by i.v. injection 20. 10(6) cancer cells (DHD/K12/TRb line) in BD-IX rats. The study of the liposome biodistribution in the rat was carried out by the use of unilamellar liposomes with homogeneous size distribution (0.1 microns), the liposomes were labeled with Cholesteryl-Bodipy. The rats were sacrificed at scheduled times after the injection; blood, urine, metastatic and healthy lung, colon, liver and spleen were analysed by a microcytofluorimetric examination. RESULTS: Liposomes prolonged the circulation time of Cholesteryl-Bodipy. Only spleen and lung metastases exhibited an accretion of fluorescent liposomes. CONCLUSIONS: The biodistribution of such formulation of liposomes in rats with lung metastases, may be of considerable importance in diagnosis and therapy of the secondaries, for increasing the concentration of tracers and therapeutic agents in tumor tissue while minimizing the likelihood of aspecific distribution and toxicity to non target tissue.

Adenocarcinoma↗
PubMed1996

[Invaginated bronchoplasty: wedge resection and sleeve reconstruction].

The purpose of this report is to illustrate a bronchoplastic technique in upper right lobectomy which is equivalent to sleeve resection but allows to preserve the unaffected portion of the bronchial wall. The technique consists in the resection of the infiltrated bronchial wall, sparing the unaffected part The distal bronchial stump is then invaginated into the stem bronchus in such a way that the anastomosis line is located at the highest possible level, ideally where it would be carried out if standard sleeve resection would be performed. The anastomosis is accomplished by U-Shaped, 3-0 vicryl sutures. The major advantage of this procedure is probably due to the preservation of the systemic artery bronchial supply to the distal stump passing through the unaffected bronchial wall; the resulting more vital distal stump may reduce incidence of suture line healing problems.

Animals↗
PubMed1996

[A device for synthesis of the costal plane after posterolateral thoracotomy using transosseous incisions to prevent compression of intercostal nerves].

The purpose of this paper is to illustrate the use of a device to quickly perform little holes in the costal lateral arch for synthesis of the standard posterolateral thoracotomy. The working principle of the instrument is similar to that of a hollow punch device. Preliminary laboratory experience allowed to identify the best diameter of the costal holes (2 mm), without fracture. Absorbable suture were passed through the holes and tied to approximate the facing ribs. The modality of costal plane synthesis, very easy and quick with this device, makes possible to prevent intercostal nerve compression and accidental intercostal vessel lacerations. The so frequent, severe and often long lasting painful sequelae of thoracotomy, on the other hand so rare in other surgical wound (i.e. laparotomy, sternotomy, etc.) justify in our opinion the routine use of this costal plane synthesis technique.

Humans↗
PubMed1995

The backflow from the pulmonary circulation for identification of the aortic origin of the bronchial arteries in experimental left single lung transplantation.

The ideal solution to the bronchial healing problems in lung transplant would be the reconstruction of the bronchial arteries at time of transplantation. The problems with this approach are essentially technical being difficult to identify and preserve the bronchial arteries in humans. The purpose of this paper is to report our experience with an experimental model in dog to easily identify and preserve bronchial circulation in single lung transplantation. The technique is based on the preservation during harvesting of the aortic origin of the first five couples of arterial orifices. Identification of the orifice(s) connected with the bronchial circulation is carried out by the backflow which takes place from the pulmonary circulation after organ reperfusion is resumed. The identified orifice(s) is then anastomosed to the descending recipient aorta, tangentially clamped.

Animals↗
PubMed1994

K-ras gene mutations: an unfavorable prognostic marker in stage I lung adenocarcinoma.

Activation of K-ras gene by point mutations, a common finding in lung adenocarcinomas, has been suggested to decrease patient survival. We investigated 109 lung adenocarcinomas, mostly small, peripheral, stage I tumours (81/109) for presence of K-ras gene mutations at codons 12 and 13. Mutations were detected by denaturing gradient gel electrophoresis analysis of specific sequences amplified by polymerase chain reaction from DNA extracted from archival pathological material. Thirty-three of 109 (30.3%) tumours showed mutations at codon 12 (28/33, 84.8%) or 13 (5/33, 15.2%) of the gene. Mutations and type of nucleotide substitutions were differently distributed among cytological subtypes, being more prevalent among less differentiated (G2 and G3) tumours and among bronchial than bronchiolo-alveolar type adenocarcinomas. Survival analysis showed an adverse effect of K-ras mutation on survival, restricted to stage I tumours. Median survival for 81 stage I patients was 30 months for non-mutated tumours versus 20 months for mutated tumours (p = 0.016). Multivariate analysis showed that age of patient (p = 0.001) and K-ras mutation status (p = 0.04) were the only independent factors influencing survival significantly. These data strengthen the hypothesis that K-ras gene mutations may be useful in identifying a subgroup of patients with poor outcome.

Adenocarcinoma↗
PubMed1993

High-frequency perfusion fluorometry (HFPF): preliminary results on a new technique for assessing bronchial mucosa blood perfusion.

A new method for estimating airway mucosa blood perfusion is proposed. It is based on the use of a high-sensitivity perfusion fluorometer, which allows us to detect the first intravascular passage of injected fluorochromes. Total measuring time can be sensibly reduced with respect to standard perfusion fluorometry, allowing us to make assessments during fiberoptic bronchoscopy. In vitro studies were performed to set up the optical arrangement of the instrument. The optimal measuring distance (2.2 mm) between the probe tip and the fluorescent mucosa was established using a fluorescent film surface to simulate fluorescent mucosa. The depth of tissue layers involved in the fluorescence emission was assessed by positioning tissue sections of different thickness between the probe tip and the fluorescent film. Tissue layers at depths not exceeding 1200 microns were found to contribute to the fluorescence signal recorded by the instrument. Mucosa blood perfusion was evaluated in rat trachea, as a model, under three different experimental conditions of vascularization: (a) basal condition (BC), (b) partial devascularization (PD), (c) full devascularization (FD). Sodium fluorescein (diffusible into the interstice) and fluorescein isothiocyanate-dextran (not diffusible into the interstice) were used as fluorescent tracers. Under the BC both substances allowed us to detect the first passage of fluorochrome through the mucosa capillary network with the same accuracy. In PD the first pass peak disappeared; total emitted fluorescence decreased as well. In FD a flat tracing was recorded. Consistent results were obtained with both substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Radioimmuno-guided endoscopy (RIGE) in the detection of primary and recurrent rectal tumor.

The usefulness of radioimmunoguided endoscopy in the detection of primary and recurrent rectal cancer was investigated. Of the 15 patients included in our study, 4 with suspected primary rectal cancer were examined preoperatively, while the remaining 11 were studied after radical resection of rectal carcinoma with the aim of detecting local recurrence. Radioimmunoguided endoscopy was performed employing a hand-held gamma-detecting probe (mod. 2 Oris, France), after the administration of a 111In labeled monoclonal antibody to CEA. Radioimmuno-guided endoscopy results detected the presence of primary or recurrent periluminal cancer in seven cases. In four it modified the preoperative stage based on the findings of conventional investigation and it influenced the surgical decision in five cases. No toxicity was noted and none of the patients developed HAMAs.

Adult↗
PubMed1992

[Postoperative infections. A prospective analysis of 1396 cases].

Postoperative infections are the most frequent complications in surgery and are the commonest cause of the lengthening of hospital stay. The purpose of this study is to prospectively evaluate the incidence and predisposing factors of postoperative infections in 1396 surgical patients admitted to our Institute from 1984 to 1988. Patients undergoing minor surgical procedures (wound less than 2 cm) were excluded from the study. Patients were evaluated daily during hospital stay for onset of infections and results recorded on data sheet. Hemocultures in septic patients and samples of exudate at site of infection were taken whenever possible for aerobic and anaerobic cultures. 368 patients (26.36%) had at least one postoperative septic complication; (79 of them [5.65%] had two or more infections). The following infections were recorded: wound infections: 148 (10.60%); respiratory tract infections: 144 (10.31%); urinary tract infections 125 (8.95%); miscellaneous infections 11 (0.78%); thrombophlebitis 23 (1.64%); FUO 10 (0.71%). The most important predisposing factor for wound infection was endogenous contamination (wound infections: 18/499 [3.60%] in clean, 42/594 [7.67%] in potentially contaminated, 57/217 [26.26%] in contaminated and 31/86 [36.04%] in dirty operations). The duration of the anaesthesia was found to correlate with an increased incidence of respiratory tract infections (4.49% anaesthesia less than 60 min; 7.21% anaesthesia greater than 60 less than 120 min; 15.31% greater than 120 min anaesthesia). Urinary infections were more frequent when the patients where catheterized at least once in the postoperative period (24.86% vs 3.2%).

Fever of Unknown Origin↗
PubMed1990

Successful bronchial revascularization in experimental single lung transplantation.

It is the purpose of this paper to report our experience with bronchial artery revascularization in an experimental model of single lung transplantation in swine. Thirty-three large white pigs weighing 20-40 kg underwent left lung allotransplantation. In 24 animals, bronchial artery revascularization was attempted by anastomizing the aortic patch containing the bronchial artery orifice with the recipient descending aorta. Eight survivors were put to death on postoperative days 11-15; five animals were put to death or died on postoperative days 2-9; the other animals died intra-operatively or within a few hours. Preservation of left bronchial vascularization was achieved in all cases attempted, as documented by post-mortem injection of dye (methylene blue) or contrast medium. Five of the 8 animals surviving for 11-15 days showed diffuse graft hepatization, associated with diffuse vascular thrombosis. Whether this was caused by damage to the endothelium due to poor graft preservation or by rejection was unclear. In animals surviving for 11-15 days without gross lung pathology, the anastomosis and bronchial mucosa were completely normal; in contrast, bronchial ischaemic changes were found in nonrevascularized animals and in survivors with graft hepatization. Our experience confirms that re-anastomosis of the bronchial arteries can prevent bronchial healing problems in single lung transplantation. The pig is an ideal model for these experiments since the bronchial arteries have a constant common aortic origin, allowing easy identification and preservation of left bronchial vascularization.

Anastomosis, Surgical↗