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J Léandri

Publications and source records attributed to J Léandri.

11 recordsLinked to original sources
PubMed1993

A new device for endothelial cell seeding of a small-caliber vascular prosthesis.

A device permitting homogeneous endothelial cell seeding of a small-caliber arterial prosthesis has been developed. The prosthesis is maintained firmly attached to a rotative scaffolding device. This device is activated by an electrical motor at constant and adjustable speed. The whole system is maintained at 37 degrees C in a cell culture incubator. The 4 mm internal diameter polytetrafluoroethylene (PTFE) prosthesis was coated with biological glue and seeded with human saphenous vein endothelial cells obtained by mechanical detachment. Cell seeding density was 2.10(4) cells/cm2 (Group A, n = 6) or 10(5) cells/cm2 (Group B, n = 6). Rotation speed was 8 revolutions per hour (rph) during 90 min. Analysis of the homogeneity of cell seeding was permitted by cell counts on five different segments of the prosthesis. Each longitudinal segment was analyzed at three different subsegments of the circumference. The average adhesion was 43 +/- 4% in Group A and 38% +/- in Group B of seeded cells. No difference could be observed between the different segments and subsegments. In the two groups, cells were spread, and in Group B, a complete endothelial cell layer was obtained on the graft surface. This study permits validation of the device to allow homogeneous cell seeding in an arterial prosthesis.

Blood Vessel Prosthesis↗
PubMed1992

[Discordant heart xenografts. Experimental study in pigs conditioned by total lymphoid irradiation and cyclosporine A].

The use of discordant xenografts may solve some of donor shortage problems. The beneficial effects of treatment with total lymphoid irradiation (TLI) and classical drugs on this discordant model of transplantation rejection was evaluated. Twenty-four lamb hearts were transplanted heterotopically in the abdomen of 24 pigs. Group I received no treatment (control). Group II received continuous intravenous medical treatment cyclosporin A (CyA) (5 mg/kg) and azathioprine (3 mg/kg) 3 days prior to transplantation. Group III received the same medical treatment and simultaneously 12 grays of irradiation in 5 equal fractions with a high rate (100 cGy/min) or a low rate (1.6 cGy/min) prior to transplantation. Group IV also received 12 grays in 5 fractions at a high rate followed by the medical treatment started 5 days after TLI and continued until the day of transplantation. Antibody and serum cyclosporine levels were monitored. Histology specimen were analyzed at the end of the experiment. Mean GST (graft survival time) in group I and II was 140 +/- 35 min and 117 +/- 27.4 min respectively. The histological features of these hearts suggested acute humoral rejection (hemorrhage, thrombosis, and edema) without cellular infiltration. In group III, one heart functioned 4.5 days with pathological features of cellular rejection and a second animal died at 6 hours with a functioning graft with no evidence of an acute rejection. Both had been treated with the low rate TLI protocol (1.6 cGy/min). The mean GST in this group was 1080 +/- 794 min. In Group IV, one graft functioned for 6.5 days and another for 3.25 days. Mean GST was significantly increased in this group to 4800 +/- 2647 min (p < 0.05). A cellular infiltration was seen in this two grafts. The remaining graft was rejected in 6 hours with histological lesions typical of acute humoral rejection. Antibodies levels at the time of transplantation were lowest (40%) in group IV and in the low rate irradiation group. The ability of TLI to induce tolerance and to prolong survival in a discordant xenograft model depends upon cumulative dose, rate of irradiation, delay between TLI and graft placement, and combined treatment with immunosuppressive drugs. A high rate of TLI and graft placement is delayed. Low rates of irradiation may be beneficial when there is a very short period between treatment and transplantation. These findings highlight the potential usefulness of TLI in combination with immunosuppressive drug therapy when antibody-mediated rejection occurs, such as with xenograft and in sensitized patient.

Animals↗
PubMed1988

Experimental model of heterotopic cardiac transplantation for evaluation of graft viability and function.

An experimental model of heterotopic intrathoracic cardiac transplantation making possible an evaluation of graft viability and function has been studied. The technique requires only two anastomoses in the normothermic state without cardiopulmonary bypass. In this model, the ascending aorta of the recipient animal may be occluded completely, enabling an increasing preload on the graft. In case of adequate myocardial preservation of the cardiac graft, the aorta may be completely occluded and the recipient systemic circulation can be sustained by the graft. However, in case of inadequate graft myocardial function, or in case of size mismatch, the recipient heart alone contributes to the circulation. This technique appears quite useful because of its simplicity, the elimination of the need for extracorporeal circulation while allowing a functional evaluation following cardiac graft preservation.

Animals↗
PubMed1984

[Influence of the type of arterial anastomosis on the development of endothelial hyperplasia].

This study was designed to evaluate intimal hyperplasia distal to the suture line in two types of vascular anastomosis: end to end and end to side. 49 aorto-iliac homografts have been performed on rabbits New-Zealand. The aortic anastomosis was side to end, iliac anastomosis were end to end on one side, end to side on the other one. Scanning electronic microscopical study and histological evaluation were carried out at various time of survival from 2 hours to 180 days. The scanning microscopy has evidenced the surface changes: early platelets adhesion and the healing process. Histological evaluation demonstrated that the intimal proliferation was prevailing at the level of the suture line in both anastomosis, and at the opposite to the mouth of the anastomosis in the end to side one. Intimal thickness was measured on arterial section immediately distal to the suture line. In the end to end anastomosis, hyperplasia was absent on the 5th post-operative days, it reached 120 mu +/- 33 on the 40th days, and decreased to 40 mu +/- 35 on the 150th post-operative day. In the end to side anastomosis evolution was the same: 0 mu on the 5th, 106 mu +/- 49 on the 40th day and 53 mu +/- 45 on the 150th post-operative day. In conclusion, this experimental study gives some support to the fact that the type of anastomosis, per se, end to side or end to end does not influence the development of intimal hyperplasia.

Animals↗
PubMed1980

Surgical transposition of the atria: A new procedure for repairing transposition of the great vessels.

The proposed procedure consists of interchanging the positions of the atria by means of an incision used in heart transplantation. After frontal sectioning of the atrial body, the heart is turned up on its pedicle, the interatrial septum is divided in its posterior part, and the vena cavae are extensively freed from their mediastinal and diaphragmatic attachments. The posterior parts of the atria can then be transposed: the right atrium and vena cava are repositioned to the left of the left atrium, and a new septum is constructed by joining the external atrial walls. The heart can then be replaced and the walls of the transposed atria repaired by edge-to-edge sutures. Cadaver experiments have indicated that this procedure is applicable in infants and young people. Casts and radiologic examinations have shown no strictures in the vena cavae, and the possibility of postoperative arrhythmias has been evaluated by means of electrocardiographic studies in dogs surviving for long periods after heart autotransplantation.

Journal Article↗