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D Houssin

Publications and source records attributed to D Houssin.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Xenotransplantation: physiopathology of hyperacute and differentiated rejection, and therapeutic perspectives].

The mechanisms of xenograft rejection involved in closely related species of donors and recipients are not the same as in disparate combinations. When the donor and the recipient are phylogenetically close, such as the monkey and the human being, the rejection of xenografts is essentially mediated by a cellular immune response, and is clinically similar to a strong allograft rejection. When the donor and the recipient belong to widely disparate species, such as in the pig-to-human combination, the graft is destroyed by a hyperacute rejection before a cellular rejection has started. Hyperacute rejection is triggered by the fixation of the recipient's preformed antibodies on the graft endothelium, and subsequent activation of the recipient's complement. The activation of endothelial cells that ensues leads to the formation of an extensive thrombosis within the graft and to its necrosis within minutes or hours after grafting. When hyperacute rejection is overcome by means of complement inhibitors, a delayed vascular rejection occurs within 36 to 48 hours, mainly involving antibody-dependent cellular cytotoxicity and contributing to the extension of the thrombosis. Both hyperacute and delayed vascular rejections can be prevented by depletion of preformed antibodies, inhibition of complement activation, or by masking the dominant xeno-epitope Gal alpha 1,3 Gal. Transgenic pigs expressing molecules that inhibit xenogeneic rejection are being produced. However, prior to any clinical use, the infectious risks, and particularly the viral risk must be evaluated.

Acute Disease↗
PubMed2000

[Medical use, current and future, of human stem cells].

Since many years, the ability to harvest and then graft haematopoietic stem cells in man has allowed to treat with success several lethal diseases in haematology and oncology. Progress in cell biology recently made possible the obtention of human stem cells, particularly of embryonic origin which, theoretically, have all the potentialities of development. Therefore, in spite of other many obstacles still ahead, the perspective of using elements produced from such cells for therapeutic purpose seems closer.

Clinical Medicine↗
PubMed1999

Costs and outcomes of liver transplantation in adults: a prospective, 1-year, follow-up study. GRETHECO study group.

BACKGROUND: Orthotopic liver transplantation (OLT) is widely used to treat patients with end-stage liver disease. However, data on the cost of the procedure are fragmentary. We evaluated the costs, as calculated from resource use, and outcomes of OLT in adults, from registration on the transplant waiting list to the end of the 1st-year of follow-up after the transplant. METHODS: Two parallel cohort studies were conducted from 1994 to 95. All patients ages 18 years and older, on the waiting list (n=33) according to national criteria or having undergone transplants (n=38) were followed for 1 year or until either the transplant (waiting list cohort) or death (waiting list and transplantation cohorts). RESULTS: Eighty percent of the patients undergoing transplants were alive after 1 year, and no patient died while on the waiting list. However, the estimated cost of the procedure was high: more than 55,000 pound silver for the 1st year after OLT, to be added to 5,500 pound silver for evaluation and further costs motivated by the planned transplant during an average 6.5 months on the waiting list. Age over 40 and a baseline Child-Pugh score of 10 and over were predictive of high costs. The proportion of costs associated with immunosuppressive therapy and rejection were very high. CONCLUSIONS: This medical and economic cohort study suggests that OLT is still expensive; the study identifies sources of extra cost that could be limited either by improved selection of patients or, in the future, by technological advances in immunosuppressive therapy that help avoid medical complications. It also suggests the situation is precarious, with outcomes and costs being very sensitive to variation in graft availability.

Adolescent↗
PubMed1999

Liposomal encapsulation of ganciclovir enhances the efficacy of herpes simplex virus type 1 thymidine kinase suicide gene therapy against hepatic tumors in rats.

Suicide gene therapy based on ganciclovir (GCV) metabolism by transgene herpes simplex thymidine kinase (HSV-1 TK) has been used to selectively kill proliferating cells in clinical settings such as cancer, vascular restenosis, and immunological disorders. We investigated whether encapsulation of ganciclovir (GCV) into liposomes would improve its efficacy, especially against hepatic tumors. Large unilamellar liposomes containing GCV were prepared by reversed-phase evaporation. Pharmacokinetic studies in rats showed that, compared with free GCV, the intravenous injection of liposome-encapsulated GCV (lip-GCV) led to a faster decrease in GCV plasma concentrations, but higher liver-blood ratios. After treatment of syngeneic HSV-1 TK+ liver metastases in rats, histologically active tumors were found in 95% of the transplanted lesions when physiological saline had been given and in 50% when free GCV had been given at 90.2 microM/kg twice daily. This dose is known to be insufficient for the eradication of HSV-1 TK+ tumors. In contrast, only 5% viable tumors were found in rats receiving lip-GCV at this same concentration. Average tumor volumes were 19 +/- 15, 7 +/- 9, and <1 mm3 for the control, free GCV, and lip-GCV groups, respectively. GCV-related toxicity was no longer observed. The results demonstrate that liposomal encapsulation of GCV is feasible and significantly enhances its efficacy against HSV-1 TK+ hepatic tumors.

Animals↗
PubMed1999

In vivo hepatocyte retrovirus-mediated gene transfer through the rat biliary tract.

Delivering retroviruses targeted to hepatocytes in vivo involves the injection of retroviruses directly into the blood stream of the portal vein. The aim of this work was to delineate the conditions for delivering retroviruses in vivo by perfusing in situ the bile duct of the regenerating rat liver, and to study the hepatocyte transgene expression. At 24 hr after partial hepatectomy, during the S phase of the cell cycle, regenerating livers were perfused for 2.8+/-0.5 hr through the bile duct with 36.2+/-6.8 ml (0.3+/-01 ml/min) of fresh culture supernatant containing amphotropic recombinant retroviruses encoding the beta-galactosidase gene. The virus total titer was 1.5 x 10(8) ffu (group I) or 6.5 x 10(8) ffu (groups II and III). The hepatic artery blood flow was either maintained (groups I and II) or interrupted (group III) during bile duct perfusion. Liver biopsies taken 7 days later showed that 31.4+/-24.2% (group I), 58.7+/-23.6% (group II), and 45.1+/-21.4% (group III) of hepatocytes expressed beta-galactosidase activity, predominantly in the periportal and mediolobular zones. This study demonstrates that hepatocytes of regenerating rat livers that have entered the S phase of the cell cycle as a result of partial hepatectomy can be transduced in vivo by retroviral vectors delivered in situ by bile duct perfusion. Furthermore, the number of transduced hepatocytes closely correlated with the viral total titer and was diminished by hepatic artery blood flow occlusion during perfusion.

Animals↗
PubMed1999

Increased expression of interleukin-4 during liver allograft rejection.

BACKGROUND/AIMS: To investigate the respective roles of interleukin-2 (IL-2) and IL-4 during rejection, we evaluated the expression of IL-2, IL-2 receptor and IL-4 in human liver allografts. METHODS: Immunohistochemistry and RT-PCR were performed in liver biopsies. To determine the effects of immunosuppression and cholestasis in IL-4 production, in vitro experiments were also designed. RESULTS: IL-2 protein and its mRNA were absent in the liver, with minimal expression of IL-2 receptor, during rejection. In contrast, IL-4 protein and its mRNA were highly expressed during acute and chronic rejection, whereas this expression was absent in stable liver transplant recipients. In vitro, cyclosporine potently inhibited IL-2 and IL-2 receptor expression of activated mononuclear blood cells, but poorly inhibited IL-4 expression. Chenodeoxycholic acid decreased IL-2 and IL-2 receptor expression, but increased IL-4 expression. CONCLUSIONS: During liver allograft rejection, IL-2 pathway is down-regulated, while IL-4 expression is increased by cholestasis and poorly inhibited by cyclosporine. These data suggest that IL-4 is involved in the mechanisms of liver allograft rejection in patients treated with cyclosporine.

Acute Disease↗
PubMed1999

Long-term outcome of liver transplantation in patients with glycogen storage disease type Ia.

Liver transplantation may be indicated in patients with GSD type Ia when dietary treatment fails or when hepatic adenomas develop, because they carry a risk of liver cancer or severe intratumoral haemorrhage. Published reports on the results of liver transplantation in patients with GSD Ia include 10 patients and provide little information on long-term outcome. In particular, it is not known whether liver transplantation prevents renal failure due to focal segmental glomerulosclerosis. We report here on 3 patients with GSD Ia in whom liver transplantation was performed at 15, 17 and 23 years of age because of multiple hepatic adenomas in all 3 patients with a fear of malignant transformation, and of poor metabolic balance and severe growth retardation in the youngest one. Renal function was normal in all patients. During the 6-8 years following transplantation, the quality of life has initially greatly improved, with none of the previous dietary restraints and a spectacular increase in height. However, long-term complications included chronic hepatitis C in one patient, gouty attacks in another and focal segmental glomerulosclerosis with progressive renal insufficiency in the third. These results: (1) confirm that liver transplantation restores a normal metabolic balance in patients with GSD Ia, allows catch-up growth and improves the quality of life; (2) suggest that liver transplantation may be considered in teenagers with unresectable multiple adenomas because of a lack of clear-cut criteria to detect malignant transformation early; and (3) suggest that liver transplantation does not prevent focal segmental glomerulosclerosis associated with GSD Ia.

Adenoma↗
PubMed1998

Predominant role of the Fab fragment in delaying hyperacute rejection in guinea pig-to-rat xenotransplantation.

BACKGROUND: Human intravenous immunoglobulin G delayed xenogeneic hyperacute rejection (HAR) in the guinea pig-to-rat combination. We investigated the respective roles of the Fc and Fab fragments of the IgG molecule in this inhibitory effect. METHODS: By using a guinea pig-to-rat heart transplantation model, the efficiency of IgG, Fab, and Fc in prolonging the grafted heart's survival time (ST) was compared. RESULTS: A dose-dependent increase in the ST was observed with Fab (r=0.74, P < 0.0001), IgG (r=0.57, P < 0.001), and Fc (r=0.51, P < 0.01). The linear regression slopes with Fab and with IgG were, respectively, sevenfold and fourfold steeper than with Fc. The ST was significantly longer than controls (23+/-7 min) after infusion of 2 g/kg IgG (147+/-42 min) or 1 g/kg Fab (176+/-38 min), whereas the highest dose of Fc (1.5 g/kg) did not induce significant prolongation of ST. In terms of equivalent functional doses, 1 g/kg Fab was significantly more potent in prolonging the ST than 1.5 g/kg IgG (87+/-25 min) or 0.5 g/kg Fc (33+/-14 min). Analysis of the rejected hearts evidenced edema, necrosis, and rat C3 deposits characteristic of HAR. CONCLUSION: These results indicated that the delaying action of intravenous immunoglobulin G on HAR in the guinea pig-to-rat combination is mostly mediated through the Fab fragment.

Animals↗
PubMed1998

[Organ donation in France. Current situation and perspectives].

RECENT CRISIS: Strict legal regulations concerning human organ procurement in France emphasize the positive aspect of donation. While public opinion in France is generally favorable, organ donation passed through a crisis during the period between 1990 and 1994. The media played a crucial role. CONFIDENCE AND COORDINATED EFFORTS: The Etablissement français des Greffes, in coordination with health care workers and non-governmental organizations, has developed a wide health education program aimed at gaining the confidence of the public and organizing hospital efforts to create an effective and serene procurement procedure. PERSPECTIVES: Procurement of cadaver organs remains essential despite the number of living-donors and ongoing development of artificial organs and xenografts.

France↗
PubMed1998

A newly established porcine aortic endothelial cell line: characterization and application to the study of human-to-swine graft rejection.

The establishment of cell lines allows reproductible in vitro studies that would be far more difficult to perform using primary cells that rapidly undergo phenotypical alterations in culture. The purpose of this work was to establish an endothelial cell line appropriate for in vitro study of endothelial cell activation during xenograft rejection. Porcine aortic endothelial cells were transfected with the early region of SV40 and selected on the basis of morphological, phenotypical, and functional features. By light and electron microscopy, the porcine aortic endothelial cell line (PAEC11) and primary cells were similar except that PAEC11 was slightly smaller. PAEC11 displayed endothelial cell characteristics since it endocytosed acetylated low density lipoproteins, produced von Willebrand factor, and expressed E-selectin. Human natural antibodies bound to the same xenoantigens on PAEC11 and primary cells. That binding was followed by human complement activation and cell lysis. In addition, PAEC11 was found appropriate for genetic engineering since it could be transfected with a plasmid encoding a foreign gene. Therefore, this cell line should be a useful model for in vitro study of endothelial cell function in general and human-to-swine xenograft rejection in particular.

Animals↗
PubMed1998

Human preformed IgG combining with membrane-bound porcine serotransferrin lyse porcine endothelial cells through antibody-dependent cellular cytotoxicity.

Preformed antibodies are involved in xenograft rejection. The purpose of this work was to characterize porcine xenoantigens recognized by human preformed IgG (hpIgG), and to investigate the role of hpIgG in xenogeneic rejection. IgG eluted from porcine livers perfused with human plasma, human sera and total human IgG were immunoblotted on porcine aortic endothelial cell extracts. The amino acid sequence of a 76-kDa antigen constantly revealed was 100% homologous with porcine serotransferrin (psTf). hpIgG from human sera, human IgG1 and IgG2 and F(ab')2gamma specifically bound to psTf. Neutralization by psTf abolished that binding. Although alpha1,3-linked galactose residues (Gal(alpha)1,3Gal) is the dominant epitope recognized by preformed antibodies in the swine-to-human combination, the analysis of carbohydrate composition of psTf showed that the molecule was devoid of Gal(alpha)1,3Gal moieties and that preformed anti-psTf IgG bound to epitopes localized on the peptide core of the molecule. Purified human anti-psTf IgG antibodies were able to bind to psTf linked to its receptor on porcine endothelial cells, and to kill those cells through antibody-dependent cellular cytotoxicity.

Amino Acid Sequence↗
PubMed1998

Hepatic regeneration in the isolated perfused rat liver followed by liver transplantation.

Controlling the S phase of the hepatocyte cell cycle would be of considerable help for stable retroviral foreign gene transfer. The aim of this article is to study hepatocyte regeneration during S phase in isolated, perfused rat liver followed by liver transplantation. Normal livers (G I: n = 7) were perfused with blood from normal rats for 6.1+/-0.3 hours. Regenerating livers (G II; n = 7) obtained 18 hours after partial hepatectomy were perfused for 6.0+/-0.3 hours with blood from rats partially hepatectomized 18 hours before. Regenerating livers (G III; n = 7) obtained 22 hours after partial hepatectomy were perfused for 2.4+/-0.1 hours with blood from normal rats. In the normothermal perfusion system, a bolus of 25 mg of 5-bromo-2'-deoxyuridine (BrdU) was added to the perfusate. Liver biopsies were taken at the end of each experiment. In group II, a biopsy was also taken 1 hour after BrdU introduction. At the end of each experiment, livers were orthotopically transplanted. The percentage of BrdU positive hepatocyte nuclei was 0.2% in G I; 14.8% and 38.4% after 1 hour and 6.1 hours, respectively, in G II; and 46.5% after 2.4 hours in G III. In G I, five rats died at day 1, 5, 6, 7, and 48 and two rats were still alive after 17 months. In G II, all the rats died before day five. In G III, two rats died at day one, one at day six, and four were still alive after 12 months. This study shows that, after 6 hours of normothermal perfusion, organ viability allows successful liver transplantation and that rat hepatocyte regeneration during cell cycle S phase in isolated normothermal conditions progresses in a similar way-quantity and timing-to liver regeneration found in vivo after partial hepatectomy.

Animals↗
PubMed1998

Early liver transplantation is crucial in children with liver disease and pulmonary artery hypertension.

BACKGROUND/AIMS: Early liver transplantation is crucial in children with liver disease and pulmonary artery hypertension. Some severe pulmonary vascular anomalies associated with portal hypertension disappear after isolated liver transplantation. Evolution of pulmonary artery hypertension due to plexogenic arteriopathy is controversial, as this association is still considered a contraindication to isolated liver transplantation. Outcome of pulmonary hypertension after isolated liver transplantation is reported in three patients with portal hypertension. METHODS: After echocardiographic diagnosis, the patients had a complete hemodynamic exploration, and two had a lung biopsy. After liver transplantation, the survivors had echocardiographic follow up and a second hemodynamic exploration. RESULTS: In two children, pulmonary pressures and resistances returned to near-normal values 1 and 6 years after successful isolated liver transplantation. The third patient, with the most severe arteriopathy, had to wait 1 year for a donor, and the attempted transplantation was complicated by ventricular tachycardia; death occurred 2 days after surgery. CONCLUSIONS: Liver transplantation can reverse pulmonary artery hypertension due to high pulmonary resistances complicating liver disease with portal hypertension, provided it is carried out at an early stage. Early detection of pulmonary hypertension by systematic echocardiography may thus be crucial in these children with portal hypertension.

Adolescent↗