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D Candinas

Publications and source records attributed to D Candinas.

At least 19 recordsLinked to original sources
PubMed2000

[Pediatric kidney transplantation and living donors--invaluable by virtue of necessity].

UNLABELLED: Renal transplantation is the treatment of choice for paediatric patients with end-stage renal failure. Living donor transplantation (LDT) has become an important therapeutic option due to the shortage of cadaver donors and increasingly long waiting times. METHODS: Between 1992 and 1999, a total of 48 paediatric and adolescent patients underwent renal transplantation in Zurich. Of these, 21 patients (44%) received a kidney from a living related donor. 11 patients had been dialysed before LDT over a period of 0.2-5.7 years (median 0.6), and 10 were transplanted preemptively. Triple immunosuppression consisted of cyclosporine A, azathioprine or mycophenolate mofetil (MMF; since 1998), and prednisone. The observation period was 0.5-7.3 years (median 2). RESULTS: Recipients were 2-18 (median 10.5) years old at transplantation. One third had either a congenital malformation, an inherited disease, or an acquired disorder. One patient died of an associated cardiac disease at 4 months with functioning graft, and one functional graft loss occurred after 2.8 years. 9 patients were switched from cyclosporine to tacrolimus, 7 for biopsy-proven rejection and 2 for cosmetic reasons (hypertrichosis). No antibody preparations were used. Median glomerular filtration rate (51Cr-EDTA), measured after one year in 11 donor/recipients, was 64 (55-95) and 54 (32-82) ml/min/1.73 m2, respectively. The most recent estimated renal function (Schwartz formula) of 19 functioning grafts was 37-79 ml/min/1.73 m2 (median 63). Median body height of 16 patients with no associated extrarenal disease was -0.9 SDS (standard deviation score); the remaining 3--with serious extra-renal disease--were considerably growth retarded. Main complications were reversible rejection episodes in 19 (90%), arterial hypertension (16), CMV disease (2) and asymptomatic CMV infection (3), pyelonephritis (3), and recurrence of the primary renal disease, seizures, diabetes mellitus and non-compliance (one each). Actuarial patient and graft survival (Kaplan-Meier) after 3 years was 95 and 83% respectively. This was not statistically different from the cadaveric donor group (n = 27) with 100 and 80% survival respectively. Overall rehabilitation was excellent. The donors were 12 mothers, 8 fathers and one grandmother aged 31 to 50 (median 39) years; none of them experienced serious postoperative problems. CONCLUSIONS: The paediatric transplantation programme would no longer be feasible in Switzerland without LDT. The results are very encouraging; preemptive transplantation makes it possible to avoid dialysis in half of the patients. The risk for the donor is small, and careful evaluation without putting pressure on the family is essential.

Adolescent↗
PubMed2000

Improved technique for infrahepatic vena cava reconstruction in guinea pig-to-rat liver transplantation.

Guinea pig-to-rat orthotopic liver transplantation is associated with serious technical problems contributing to impaired graft perfusion and primary graft failure. In order to shorten the procurement procedure and thereby minimize liver damage before flushing, a simplified technique for infrahepatic caval reconstruction was developed. Dissection of the infrahepatic vena cava (IHVC) from adrenal glands and renal and lumbar veins represents the most difficult and time-consuming part of the donor operation, which is often not well tolerated by the animal; we avoided this step by using an isogeneic vena cava interposition graft (VCIG) following in situ perfusion. This graft is connected with the IHVC transsected just below the liver with a cuff technique. Donor operations lasted 15 to 20 minutes with the new technique (n = 7) compared to 52 to 76 minutes with conventional technique (n = 7). Reduced operating time was associated with markedly improved graft perfusion and significantly better graft survival. This modification of the donor procedure for the guinea pig-to-rat liver xenograft using a VCIG significantly reduces operating time and improves reperfusion and recipient survival.

Anastomosis, Surgical↗
PubMed1999

Reduced kidney transplant rejection rate and pharmacoeconomic advantage of mycophenolate mofetil.

BACKGROUND: Several multinational controlled clinical trials have shown that triple therapy immunosuppressive regimens which include mycophenolate mofetil (MMF), cyclosporin A (CSA) and steroids (S) are superior compared with conventional regimens which include azathioprine (AZA), CSA and S, mainly because MMF reduces the rate of acute rejection episodes in the first 6 months after kidney transplantation. Post-marketing studies are useful to evaluate the general applicability and costs of MMF-based immunosuppressive regimens. METHODS: Based on the excellent results of the published controlled clinical trials, we have changed the standard triple therapy immunosuppressive protocol (AZA+CSA+S) to an MMF-based regimen (MMF+CSA+S) at our centre. To analyse the impact of this change in regimen, we have monitored 6-month patient and graft survival, rejection rate, serum creatinine and CSA levels, as well as the costs of the immunosuppressive and anti-rejection treatments, in 40 consecutive renal transplant recipients (MMF group) and have compared the data with 40 consecutive patients transplanted immediately prior to the change in regimen (AZA group). RESULTS: Recipient and donor characteristics were similar in the AZA and MMF groups. Patient survival (37/40; 92.5% in the AZA group vs 38/40; 95% in the MMF group), graft survival (36/40 vs 36/40; both 90%) and serum creatinine (137+/-56 vs 139+/-44 micromol/l) after 6 months were not significantly different. However, the rate of acute rejection episodes (defined as a rise in creatinine without other obvious cause and treated at least with pulse steroids) was significantly reduced with MMF from 60 to 20% (P=0.0005). The resulting cost for rejection treatment was lowered 8-fold (from sFr. 2113 to 259 averaged per patient) and the number of transplant biopsies was lowered > 3-fold in the MMF group. The cost for the immunosuppressive therapy was increased 1.5-fold with MMF (from sFr. 5906 to 9231 per patient for the first 6 months). CONCLUSIONS: The change from AZA to MMF resulted in a significant reduction in early rejection episodes, resulting in fewer diagnostic procedures and rehospitalizations. The optimal long-term regimen in terms of patient and pharmacoeconomic benefits remains to be defined.

Adult↗
PubMed1999

[Mechanisms of xenotransplant rejection].

The recent shortage of allogeneic human organs in transplantation medicine has led to a renewed interest in evaluating the feasibility of xenotransplantation, particularly of porcine origin. Discordant xenotransplants between phylogenetically distant species such as pig and primates are challenged by a series of strong rejection reactions. Hyperacute rejection is dominantly mediated by humoral responses of the immune system (natural antibodies, complement cascade) and the activation of coagulation factors, whereas delayed xenograft rejection and T-cell mediated responses are also mediated by elements of the cellular immune system. The mechanisms of chronic xenograft rejection remain to be elucidated. The present review is focused on the mechanisms of rejection and the immunobiology of discordant, vascularized xenotransplants. We attempt to provide a brief description of the dynamics, the humoral and cellular mediators, and the pathogenesis of xenograft rejection. Finally, an overview on potentially therapeutic strategies to overcome xenograft rejection is presented.

Animals↗
PubMed1998

Transient complement inhibition plus T-cell immunosuppression induces long-term survival of mouse-to-rat cardiac xenografts.

BACKGROUND: The use of anti-B-cell and T-cell immunosuppressive agents leads to only a few weeks' survival of mouse-to-rat cardiac xenografts. METHODS: BALB/c cardiac xenografts were transplanted to Lewis rats treated with cyclosporine (CsA) and/or cobra venom factor (CVF). RESULTS: CsA alone did not prolong xenograft survival (2.2+/-0.4 days), whereas CVF alone led to minimal prolongation of survival (5.6+/-0.8 days) as compared with nontreated recipients (2.4+/-0.5 days). The combination of CsA plus CVF, the latter given for either 2 days or 11 days, resulted in long-term survival of 14/16 hearts (> 100 days). Production of IgM elicited xenoreactive antibodies (EXA) peaked on day 4 after transplantation and decreased thereafter. Production of IgG EXA occurred only in the control group, whereas, in the CsA/CVF-treated group, IgG EXA were totally suppressed. Long-term surviving grafts showed (i) excellent preservation of morphology and minimal leukocyte infiltration, (ii) deposition of IgM, IgG and weak C3 deposition on the graft endothelium, (iii) low level infiltration by rat macrophages, (iv) replacement of mouse dendritic cells by class II+ rat macrophages, and (v) expression within endothelial and smooth muscle cells, macrophages, and myocytes of HO-1, a "protective gene" not seen in the rejected hearts. CONCLUSIONS: Our present findings suggest that long-term mouse-to-rat cardiac xenograft survival is induced by temporary suppression of C activation and sustained T-cell suppression leading to inhibition of IgG EXA production. Florid expression of a protective gene (HO-1) may contribute to survival.

Animals↗
PubMed1998

Percutaneous drainage of abdominal abscesses: are large-bore catheters necessary?

OBJECTIVE: To find out whether small-bore catheters (7 F) are as effective as the 14F sump drains generally used for drainage of abdominal abscesses. DESIGN: Retrospective review. SETTING: University hospital, Switzerland. SUBJECTS: 64 patients with intra-abdominal abscesses. INTERVENTIONS: 40 were drained with 7F pigtail catheters and 24 by 14F sump drains. RESULTS: Drainage was successful in 34/40 (85%) and 20/24 (83%), respectively. There were 3 recurrences in the small-bore and 1 in the large-bore group (p=0.4). Mean drainage time was 8 (SD 5) days and 11 (SD 11) days, respectively (p=0.29). One patient (3%) developed a complication in the small-bore group and 2 (8%) in the large-bore group. 4/6 failures in the small-bore group and 1/4 failures in the large-bore group were pancreatic abscesses. CONCLUSIONS: We conclude that percutaneous drainage with small-bore catheters is as effective as drainage with bigger tubes.

Abdominal Abscess↗
PubMed1998

[33 years kidney transplantation in Zurich].

This article summarizes our experience with renal transplantation over the past 33 years and shows progressive improvement of the clinical outcome over time. In parallel we observed an increasing proportion of elderly recipients and diabetics. The increasing shortage of cadaver grafts was compensated by using donor hearts from legally dead donors (heart no longer beating) and establishing a living donor program.

Adult↗
PubMed1998

[Kidney retransplantation in relation to organ shortage].

This article reviews our experience with renal regrafting in the past 16 years with particular emphasis on long-term outcome and prognostic parameters. Among 1094 renal transplants there were 15.8% regrafts, and the proportion of patients awaiting a regraft procedure on our current waiting list is 33%. Graft and patient survival was similar for first and second transplants, but was significantly reduced when a third graft was performed. The main prognostic parameters were the time of function of the previous graft, mismatch for HLA-DR and the presence of panel-reactive antibodies.

Histocompatibility Testing↗
PubMed1997

Loss of ATP diphosphohydrolase activity with endothelial cell activation.

Quiescent endothelial cells (EC) regulate blood flow and prevent intravascular thrombosis. This latter effect is mediated in a number of ways, including expression by EC of thrombomodulin and heparan sulfate, both of which are lost from the EC surface as part of the activation response to proinflammatory cytokines. Loss of these anticoagulant molecules potentiates the procoagulant properties of the injured vasculature. An additional thromboregulatory factor, ATP diphosphohydrolase (ATPDase; designated as EC 3.6.1.5) is also expressed by quiescent EC, and has the capacity to degrade the extracellular inflammatory mediators ATP and ADP to AMP, thereby inhibiting platelet activation and modulating vascular thrombosis. We describe here that the antithrombotic effects of the ATPDase, like heparan sulfate and thrombomodulin, are lost after EC activation, both in vitro and in vivo. Because platelet activation and aggregation are important components of the hemostatic changes that accompany inflammatory diseases, we suggest that the loss of vascular ATPDase may be crucial for the progression of vascular injury.

Adenosine Diphosphate↗
PubMed1997

In situ repair of aortobronchial, aortoesophageal, and aortoenteric fistulae with cryopreserved aortic homografts.

PURPOSE: The surgical treatment of fistulae that originate from aortic aneurysms or prosthetic aortic grafts carries a high mortality rate. We investigated whether in situ repair with cryopreserved aortic homografts would improve the outcome. METHODS: Between April 1994 and June 1996, 11 patients (mean age, 62 +/- 10 years) with aortobronchial, aortoesophageal, or aortointestinal fistulae originating from mycotic aneurysms (five of 12) or prosthetic aortic grafts (six of 12) underwent in situ replacement of the thoracic (seven of 10) or abdominal (four of 10) aorta with homografts. Emergency surgery was performed in eight of 11 patients (73%). RESULTS: The hospital mortality rate was 9%; there was one sudden cardiac death on the seventh postoperative day. The mean hospital stay was 42 +/- 26 days (range, 21 to 90 days). After surgery, antibiotics were given for 38 +/- 6 days (range, 28 to 42 days). Neither reinfection, suture line rupture, nor anastomotic aneurysms were observed by magnetic resonance angiography, computed tomography, angiography, or transesophageal echocardiography after 14.3 +/- 8.2 months (range, 6 to 31 months). In one patient, percutaneous vascular stent placement was necessary after 18 months for an anastomotic stenosis of a thoracic homograft. CONCLUSIONS: In situ repair with cryopreserved aortic homografts seems to be a promising step in the treatment of aortobronchial, aortoesophageal, and aortointestinal fistulae. This technique has a low operative mortality rate and may prevent reinfection.

Aged↗
PubMed1997

Donor pretreatment with leflunomide has an adverse effect on rat cardiac allograft survival.

The effect of leflunomide (Lef) donor pretreatment (DPT) on rat cardiac allograft survival was investigated. In untreated Lewis recipients of untreated DA hearts, median graft survival was 5 days. DPT (Lef 5 or 10 mg/kg per day for 30 days) reduced median graft survival to 4.0 and 4.5 days, respectively. In immunosuppressed (Lef 5 mg/kg for 10 or 30 days) Lewis recipients of untreated DA hearts, median graft survival was 21 and 33 days, respectively. DPT with Lef 5 mg/kg per day for 5 days or 30 days reduced median graft survival to 12 and 23.5 days, respectively (p < 0.05). DPT with Lef resulted in earlier graft rejection but the histological appearance at the time of rejection was the same as in untreated controls. DPT with Lef resulted in a 40% reduction in MHC class II-positive cells in the heart. Histological examination of rejecting hearts showed no obvious difference in the nature of the rejection process between DPT and untreated control hearts. The paradox between class II reduction but earlier rejection indicates that DPT is exerting a deleterious effect through some unrecognized property of the graft.

Animals↗
PubMed1997

Accommodation of vascularized xenografts: expression of "protective genes" by donor endothelial cells in a host Th2 cytokine environment.

Organ xenografts under certain circumstances survive in the presence of anti-graft antibodies and complement, a situation referred to as "accommodation." We find that the endothelial cells (ECs) in hamster hearts that accommodate themselves in rats express genes, such as A20 and bcl-2, that in vitro protect ECs from apoptosis and prevent upregulation in those cells of proinflammatory genes such as cytokines, procoagulant and adhesion molecules. Hearts that are rejected do not express these genes. In addition, vessels of rejected hearts show florid transplant arteriosclerosis whereas those of accommodated hearts do not. Accommodated xenografts have an ongoing T helper cell type 2 (Th2) cytokine immune response, whereas the rejected grafts have a Th1 response. We propose a model for factors that contribute to the survival of xenografts and the avoidance of transplant arteriosclerosis.

Animals↗
PubMed1996

Apyrase administration prolongs discordant xenograft survival.

Platelet thrombi and vascular inflammation are prominent features of discordant xenograft rejection. The purinergic nucleotides ATP and ADP, which are secreted from platelets and released by injured endothelial cells (EC), are important mediators of these reactions. Quiescent EC express the ectoenzyme ATP-diphosphohydrolase (ATPDase; an apyrase), which exerts an important thromboregulatory function by hydrolyzing both ATP and ADP. We have shown that ATPDase activity is rapidly lost from the surface of the EC following ischemia-reperfusion injury and during xenograft rejection. The aim of this study was to supplement ATPDase activity within xenografts by infusion of soluble apyrases, and thereby validate the importance of local ATPDase activity in the modulation of xenograft rejection. Lewis rats underwent heterotopic cardiac xenografting from guinea pigs and apyrase was administered intravenously (200 U/kg) as a single dose to evaluate effects on hyperacute rejection (HAR). This initial dose was followed by a continuous apyrase infusion (8.0 U/kg/hr) directly into the graft aorta in combination with systemic cobra venom factor (CVF) administration to deplete complement when delayed xenograft rejection (DXR) was studied. Functional apyrase levels in vivo were assessed by the capacity of blood samples taken at the time of surgery and rejection to inhibit platelet aggregation in vitro. Apyrase administration significantly prolonged graft survival in HAR and DXR. Functional assays showed inhibition of platelet aggregation suggesting effective systemic antiaggregatory effects of the administered apyrases. Histologic studies showed that apyrase administration abrogated local platelet aggregation and activation in HAR and DXR. Our data demonstrate that local administration of apyrase prolonged discordant xenograft survival. These observations emphasize the potential importance of purinergic mediators in platelet activation during xenograft rejection.

Adenosine Diphosphate↗
PubMed1996

Immunomodulatory effects of the alkaloid sinomenine in the high responder ACI-to-Lewis cardiac allograft model.

Extracts of the plant Sinomenium acutum have been used safely since ancient times in Chinese medicine for treatment of rheumatic diseases, and the purified alkaloid, sinomenine, was recently shown to have anti-inflammatory and antirheumatic effects. This study describes the effects of sinomenine in the high responder ACI-->Lewis cardiac transplant model in which allograft rejection occurred at 5 days posttransplant. Treatment with sinomenine (15-30 mg/kg/day i.p.) or a subtherapeutic dose of cyclosporine (CsA, 1.5 mg/kg/day, i.m.) prolonged allograft survival only marginally (mean survival of 5.4 and 7.8 days, respectively). In contrast, the combination of sinomenine and CsA had a statistically significant synergistic effect, with a mean survival of 42.2 days (P < 0.001). Allografts harvested at day 5 from recipients treated with either sinomenine or CsA showed dense mononuclear cell infiltrates with widespread subepicardial infarcts, edema, and microvascular platelet and fibrin deposition. Immunohistologic analysis showed that intragraft leukocytes consisted of >75% macrophages with approximately 10-20% T cells and <5% B or NK cells. Mononuclear cell activation was shown by expression of IL-2R (CD25, 10-20%) and labeling for IL-2 (approximately 10%), and IFN-gamma (10-20%), as well as TNF-alpha (>50%) and iNOS (>50%), but only low levels of IL-4 or IL-10 (<5%). Intragraft endothelial cells were activated, as shown by upregulation of MHC class II antigen and ICAM-1 (CD54) compared with only basal levels in normal donors hearts. Combined sinomenine/CsA therapy significantly enhanced graft morphology, resulting in only mild mononuclear cell infiltration, and an absence of infarcts, platelets, or fibrin deposition. Though residual intragraft mononuclear cells at day 5, as in control grafts, consisted primarily of macrophages plus small numbers of IL-2R+ T cells, these cells lacked expression of IL-2, had only low levels of IFN-gamma, but showed dense labeling for IL-4 and IL-10. In addition, TNF-alpha and iNOS were reduced to basal levels and no endothelial cell activation was observed, despite high titers of endothelium-bound IgM, IgG, and C3. Mitogen-induced in vitro proliferation of rat thymocytes was also more effectively decreased by the sinomenine/CsA combination than by either agent alone. These studies demonstrate the therapeutic value of sinomenine in transplantation, and indicate that this agent has novel and interesting antimacrophage, T cell, and endothelial effects that warrant further evaluation.

Adjuvants, Immunologic↗