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Dive into the research topics where Jean Tchervenkov is active.

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Featured researches published by Jean Tchervenkov.


Transplantation | 1998

Comparison of neoral dose monitoring with cyclosporine through levels versus 2-hr postdose levels in stable liver transplant patients.

Marcelo Cantarovich; Jeffrey Barkun; Jean Tchervenkov; Jean-Guy Besner; Launa Aspeslet; Peter Metrakos

BACKGROUND We reported that cyclosporine 2-hr postdose levels (C2) correlate better with the AUC0-4 hr than trough levels (C0) in heart transplant patients receiving Neoral. METHODS We compared Neoral dose adjustment with C0 (group 1: 100-200 ng/ml) vs. C2 (group 2: 700-1000 ng/ml; group 3: 300-600 ng/ml) in 35 stable adult patients >1 year after liver transplantation. The AUC0-4hr was calculated, and simultaneous blood samples were obtained to measure calcineurin inhibition. Clinical benefit was defined as the absence of rejection and no increase in serum creatinine at the 7-month follow-up. RESULTS C2 correlated better with the AUC0-4 hr than C0 (r=0.92 vs. r=0.40). Neoral dose increased by 17% and 39% in groups 1 and 2, and decreased by 18% in group 3 (P=0.002 vs. group 1 and P=0.0004 vs. group 2). Serum creatinine increased by 2.1% and 16% in groups 1 and 2, and decreased by 5.1% in group 3 (P=0.006 vs. group 2). A clinical benefit was observed in 37.5%, 23%, and 82% of patients in groups 1, 2, and 3 (P=0.03 vs. group 1 and P=0.01 vs. group 2). Calcineurin inhibition was similar in all groups at 2-hr (44+/-17%, 39+/-30%, and 44+/-35%), in spite of different Neoral doses (2.9+/-0.9, 4.0+/-1.8, and 2.6+/-1.3 mg/kg/day) and C2 (857+/-226, 922+/-274, and 588+/-274 ng/ml). CONCLUSIONS C2 correlated better with the AUC0-4 hr than C0. Neoral dose monitoring with a C2 range of 300-600 ng/ml resulted in a lower dose and greater clinical benefit compared to C0 or a higher C2 in stable liver transplant patients. The correlation between calcineurin inhibition and clinical events deserves further research.


American Journal of Transplantation | 2011

Transporting live donor kidneys for kidney paired donation: initial national results.

Dorry L. Segev; Jeffrey Veale; J. C. Berger; J. M. Hiller; R. L. Hanto; D. B. Leeser; S. R. Geffner; Shalini Shenoy; W. I. Bry; S. Katznelson; Marc L. Melcher; Michael A. Rees; E. N. S. Samara; Ajay K. Israni; Matthew Cooper; R. J. Montgomery; L. Malinzak; James F. Whiting; D. Baran; Jean Tchervenkov; John P. Roberts; Jeffrey Rogers; David A. Axelrod; C. E. Simpkins; Robert A. Montgomery

Optimizing the possibilities for kidney‐paired donation (KPD) requires the participation of donor–recipient pairs from wide geographic regions. Initially it was envisaged that donors would travel to the recipient center; however, to minimize barriers to participation and simplify logistics, recent trends have involved transporting the kidneys rather than the donors. The goal of this study was to review outcomes of this practice. KPD programs throughout the United States were directly queried about all transplants involving live donor kidney transport. Early graft function was assessed by urine output in the first 8 h, postoperative serum creatinine trend, and incidence of delayed graft function. Between April 27, 2007 and April 29, 2010, 56 live donor kidneys were transported among 30 transplant centers. Median CIT was 7.2 h (IQR 5.5–9.7, range 2.5–14.5). Early urine output was robust (>100 cc/h) in all but four patients. Creatinine nadir was <2.0 mg/dL in all (including the four with lower urine output) but one patient, occurring at a median of 3 days (IQR 2–5, range 1–49). No patients experienced delayed graft function as defined by the need for dialysis in the first week. Current evidence suggests that live donor kidney transport is safe and feasible.


Transplantation | 2012

Clostridium difficile colitis: Increasing incidence, risk factors, and outcomes in solid organ transplant recipients

Marylise Boutros; Maha Al-Shaibi; Gabriel Chan; Marcelo Cantarovich; Elham Rahme; S. Paraskevas; Marc Deschenes; Peter Ghali; Philip Wong; Myriam Fernandez; Nadia Giannetti; Renzo Cecere; Mazen Hassanain; Prosanto Chaudhury; Peter Metrakos; Jean Tchervenkov; Jeffrey Barkun

Background Clostridium difficile-associated diarrhea (CDAD) is an increasingly important diagnosis in solid organ transplant recipients, with rising incidence and mortality. We describe the incidence, risk factors, and outcomes of colectomy for CDAD after solid organ transplantation. Methods Patients with CDAD were identified from a prospective transplant database. Complicated Clostridium difficile colitis (CCDC) was defined as CDAD associated with graft loss, total colectomy, or death. Results From 1999 to 2010, we performed solid organ transplants for 1331 recipients at our institution. The incidence of CDAD was 12.4% (165 patients); it increased from 4.5% (1999) to 21.1% (2005) and finally 9.5% (2010). The peak frequency of CDAD was between 6 and 10 days posttransplantation. Age more than 55 years (hazard ratio [HR]: 1.47, 95% confidence interval [CI]=1.16–1.81), induction with antithymocyte globulin (HR: 1.43, 95% CI=1.075–1.94), and transplant other than kidney alone (liver, heart, pancreas, or combined kidney organ) (HR: 1.41, 95% CI=1.05–1.92) were significant independent risk factors for CDAD. CCDC occurred in 15.8% of CDAD cases. Independent predictors of CCDC were white blood cell count more than 25,000/&mgr;L (HR: 1.08, 95% CI=1.025–1.15) and evidence of pancolitis on computed tomography scan (HR: 2.52, 95% CI=1.195–5.35). Six patients with CCDC underwent colectomy with 83% patient survival and 20% graft loss. Of the medically treated patients with CCDC (n=20), the patient survival was 35% with 100% graft loss. Conclusions We have identified significant risk factors for CDAD and predictors of progression to CCDC. Furthermore, we found that colectomy can be performed with excellent survival in selected patients.


Canadian Journal of Gastroenterology & Hepatology | 2007

Preoperative alpha-fetoprotein slope is predictive of hepatocellular carcinoma recurrence after liver transplantation.

Kathy Han; George N Tzimas; Jeffrey Barkun; Peter Metrakos; Jean Tchervenkov; Nir Hilzenrat; Phil Wong; Marc Deschenes

BACKGROUND Liver transplantation (LT) offers a possible cure for patients with hepatocellular carcinoma (HCC) and cirrhosis. However, tumour progression while on the waiting list and tumour recurrence after LT are common. The prognostic significance of various pre- and postoperative variables were investigated in regard to tumour recurrence, with an emphasis on the slope of preoperative serum alpha-fetoprotein (AFP) levels. patients and METHODS Data from 48 patients who had HCC diagnosed preoperatively and underwent LT at the McGill University Health Centre (Montreal, Quebec) were reviewed retrospectively, and possible risk factors for tumour recurrence were examined. RESULTS Univariate analysis revealed a positive correlation between the preoperative AFP slope and vascular invasion (P = 0.045), total tumour diameter at explant (P = 0.040), Cancer of the Liver Italian Program score (P = 0.017) and recurrence-free survival (P = 0.028). Of the preoperative variables examined, only the preoperative AFP slope was identified as an independent predictor of tumour recurrence by multivariate analysis. Receiver operating characteristic analysis showed that the best discriminant cut-off value, calculated as the value of the maximized likelihood ratio, was preoperative AFP slope greater than 50 microg/L per month. At this cut-off, sensitivity was 36%, and specificity was 97%. Patients with a preoperative AFP slope greater than 50 microg/L per month had a much worse one-year recurrence-free survival rate than those with a preoperative AFP slope 50 microg/L per month or less (40% versus 90%, P < 0.001). CONCLUSIONS These results suggest that the preoperative AFP slope is an important predictor of HCC recurrence after LT and should be examined in future studies of patients receiving LT for HCC.


Transplantation | 2001

Pseudoaneurysm of the superior mesenteric artery after pancreas transplantation treated by endovascular stenting.

Michael Tan; Antonio Di Carlo; Lawrence A. Stein; Marcelo Cantarovich; Jean Tchervenkov; Peter Metrakos

Pseudoaneurysm after pancreas transplantation can have serious consequences, including rupture, hemorrhage, and graft loss. We describe a 38-year-old patient who presented with a pseudoaneurysm of the donor superior mesenteric artery 1 month after pancreas transplantation. Selective arteriography was performed and the lesion was repaired with endovascular placement of a 28-mm covered stent. Laparotomy was avoided. The pancreatic graft was continuing to function well 9 months later. As far as we know, this minimally invasive approach was not previously reported. According to published series, pseudoaneurysms often occur secondary to infection and require operative intervention necessitating graft pancreatectomy. Patients can present with serious symptoms including hypotension and shock. Therefore, it is important to detect pseudoaneurysm in a timely manner. Computed tomography and Doppler ultrasound are important diagnostic tools in this regard. We demonstrated the utility of endovascular stenting in the treatment of pseudoaneurysm after pancreas transplantation. When used in a timely manner in well selected patients, endovascular stenting can abrogate the need for operative intervention and its attendant morbidity.


Annals of Surgery | 1997

Recurrence-free long-term survival after liver transplantation for hepatitis B using interferon-alpha pretransplant and hepatitis B immune globulin posttransplant.

Jean Tchervenkov; A.J. Tector; Jeffrey Barkun; A Sherker; C D Forbes; Nahel Elias; M. Cantarovich; P Cleland; Peter Metrakos; J L Meakins

OBJECTIVE The authors determined whether pretransplant reduction of hepatitis B virus (HBV) load using alpha-interferon-2b (IFN) and passive immunoprophylaxis using hepatitis B immunoglobulin (HBIg) posttransplantation can prevent HBV recurrence in patients undergoing liver transplantation (LT) for HBV cirrhosis. SUMMARY BACKGROUND DATA Liver transplantation in patients with HBV cirrhosis is associated with a high rate of recurrence and reduced survival. In patients with evidence of replicating virus (HBV-DNA or hepatitis B e antigen [HBeAg]-positive serum or both), recurrence is nearly universal. Passive immunoprophylaxis with HBIg alone is not effective in preventing HBV recurrence posttransplant, especially in patients with evidence of active viral replication pretransplant. Higher doses of HBIg posttransplant has reduced recurrence rates to 30% to 50%. Lamivudine, a nucleoside analogue that has shown early promise, also is associated with significant HBV recurrence. The authors report a reliable method of preventing viral recurrence in patients even with evidence for active HBV replication pretransplant. METHODS Pretransplant patients with evidence of replicating HBV were given IFN starting at 1 million IU 3 times per week subcutaneously. This dose was increased to 2 and then 3 million IU 3 times per week when patients side effects permitted and was maintained until the patient underwent a LT. All patients were tested every 4 weeks for hepatitis B surface antigen (HBsAg), HBeAg, and HBV-DNA. When patients became negative for HBeAg and HBV-DNA, they were listed for LT. Patients that were only HBsAg positive were listed immediately and received a LT without prior IFN treatment. Post-LT, all patients began receiving HBIg 2000 IU (10 mL) daily from days 1 to 20 and then weekly for the first 2 years. After 2 years, all patients received 2000 IU (10 mL) monthly. Additional HBIg immunoprophylaxis was given during intense immunosuppression for rejection. Posttransplant serum was tested for HBsAg, HBeAg, and HBV-DNA in all patients 1 week, 1 month, and every 3 months thereafter. Liver biopsies were done at least yearly and when liver enzymes were abnormal and were always tested for HBsAg and HBcAg by immunoperoxidase. RESULTS Thirteen patients with decompensated HBV cirrhosis were transplanted. Pretransplant, eight patients had evidence of active viral replication at the initial assessment (HBeAg or HBV-DNA-positive serum or both). All eight were successfully treated with IFN (median duration, 24 weeks; range, 8-53) and converted to a negative status before transplantation. Side effects from IFN were minimal and well tolerated, except in one patient who required 6 million IU to convert to a nonreplicating status. The five patients that were only HBsAg positive were not treated with IFN pretransplant. After surgery, HBIg given as described achieved consistently serum levels greater than 1000 IU/L. Twelve of the 13 patients are alive with normal liver function and without serologic evidence of HBV recurrence at a median follow-up of 32 months (range, 9-56 months). None have evidence of HBV recurrence as measured by serum HBsAg/HBeAg/HBV-DNA at recent follow-up. The sera of the seven longest survivors has tested negative for HBV-DNA using the polymerase chain reaction method. In addition, a liver biopsy was obtained in six of these patients, the results of which also tested negative for HBV-DNA using polymerase chain reaction. Liver biopsy specimens have been negative for the presence of HBsAg and HBcAg by immunoperoxidase staining in all 12 patients. CONCLUSION A reduction of viral load pretransplant with IFN and posttransplant HBIg prevents recurrence of hepatitis B and permits LT for HBV cirrhosis, even in patients with evidence of replicating virus. The IFN pretransplant was well tolerated, and the small frequent dosing of HBIg posttransplant did not cause side effects while achieving serum levels > 1000 IU/L.


Clinical Journal of The American Society of Nephrology | 2009

Management of Chronic Allograft Nephropathy: A Systematic Review

Leora M. Birnbaum; Mark L. Lipman; Steven Paraskevas; Prosanto Chaudhury; Jean Tchervenkov; Dana Baran; Andrea Herrera-Gayol; Marcelo Cantarovich

Despite improving immunosuppressive protocols in renal transplantation, chronic allograft nephropathy (CAN) remains a major impediment to long-term graft survival. The optimal immunosuppressive regimen for a patient with CAN is unknown. The aim of this study is to evaluate the various immunosuppressive management strategies of biopsy-proven CAN and of chronic allograft dysfunction (CAD) (no biopsy). A systematic review of randomized trials (n = 12 trials with 635 patients) was conducted. Studies included patients who were >6 mo post-transplant. All patients were on a calcineurin inhibitor (CNI), most often cyclosporine, and were randomized to convert to mycophenolate mofetil (MMF), tacrolimus, or sirolimus (Rapa) or to add azathioprine, MMF or Rapa to their current regimen. Follow-up time was 6 to 36 mo. The outcome measures evaluated were renal function in 11 of 12 studies and repeat renal biopsy results in one study. The methodological quality scores of the trials were generally low, using the Jadad scale (median value 2/5). Results varied between studies but suggested that CNI withdrawal is safe and that conversion to MMF or Rapa may be beneficial. The incidence of adverse effects ranged from 0% to 68% between the studies, and medication withdrawal occurred in 0% to 24% of patients. The review did not result in a consensus regarding the management of CAN and CAD. Further studies are required to determine the best therapeutic option for patients with CAD and CAN.


Transplant International | 2006

Recipient age and risk of chronic allograft nephropathy in primary deceased donor kidney transplant

Douglas S. Keith; Marcelo Cantarovich; S. Paraskevas; Jean Tchervenkov

Single center and registry data studies have had conflicting results regarding the impact of recipient age on chronic allograft nephropathy (CAN). We tested the hypothesis that advanced recipient age is a risk factor for graft failure due to CAN. All patients who underwent primary deceased donor kidney transplant between January 1, 1995 and December 31, 2000 recorded in the United Network of Organ Sharing (UNOS) database were analyzed for the occurrence of death censored graft loss and by two different definitions of graft loss due to CAN. Kaplan–Meier analysis based on the recipient age, and Cox proportional hazard regression was used to estimate the independent effect of recipient age on the three endpoints of interest. For all endpoints, after age of 9 years, the risk of graft loss declined with each successive decade increase in age. This pattern of risk was similar for both Caucasian and African‐American recipients, although for any given age the risk of graft loss was always higher in African‐American recipients. Analysis of UNOS data does not support the hypothesis that advanced recipient age is a risk factor for CAN.


Transplantation | 2002

Anti-CD25 monoclonal antibody coverage allows for calcineurin inhibitor "holiday" in solid organ transplant patients with acute renal dysfunction.

Marcelo Cantarovich; Peter Metrakos; Nadia Giannetti; Renzo Cecere; Jeffrey Barkun; Jean Tchervenkov

Background. Solid organ transplant (Tx) patients on calcineurin inhibitors (CNI) can develop acute renal dysfunction (ARD), which could be improved by reducing or withholding (“holiday”) CNI dose. Methods. We used anti-CD25 monoclonal antibodies to prevent acute rejection in 11 adult Tx patients (7 heart, 2 liver, 2 heart-renal Tx), requiring a CNI “holiday” because of 15 events of ARD after the initial postTx hospitalization. An event of ARD was defined as an increase in serum creatinine (Scr)>25% vs. baseline. The CNI “holiday” was implemented until Scr had decreased to baseline. Basiliximab was used in 7 patients (11 events), and daclizumab was used in 4 patients (4 events). Results. The CNI “holiday” was implemented over 21±51 days. Anti-CD25 mAb were well tolerated with no episodes of acute rejection. Scr (&mgr;mol/liter) increased from 145±48 to 301±92 (P <0.0001), and decreased to 143±55 with the CNI “holiday.” Conclusions. Our results suggest that a CNI “holiday” may improve ARD after solid organ Tx without rejection under anti-CD25 mAb coverage.


Transplantation | 2013

Pretransplantation α-fetoprotein slope and milan criteria: strong predictors of hepatocellular carcinoma recurrence after transplantation.

Teodora C. Dumitra; Sinziana Dumitra; Peter Metrakos; Jeffrey Barkun; Prosanto Chaudhury; Marc Deschenes; Steven Paraskevas; Mazen Hassanain; Jean Tchervenkov

Background Hepatocellular carcinoma (HCC) is a major cause of orthotropic liver transplantations (OLT). However, tumor recurrence remains a concern. Our group has shown that a rising natural &agr;-fetoprotein (AFP) slope (NAS) correlates with tumor characteristics. We want to assess if a rising NAS predicts tumor recurrence. Methods We reviewed first OLT for HCC (n=144) at our center from 1992 to 2010. Patients with less than two AFP values before treatment were excluded (n=52). A rising NAS (>0.1 &mgr;g/L/day) was found in 28 patients whereas 64 presented a stable or dropping NAS. Demographics, pre-OLT therapy, and tumor characteristics were collected. Statistical analysis was performed using ANOVA, chi-square or Fisher’s test, and logistic regression for recurrence after OLT. Results Demographics were similar among the recurrence (n=12) and nonrecurrence (n=80) groups. Patients who recurred received more treatment (P=0.017), had a higher number of lesions (P=0.025), a greater total tumor size (P=0.001), and a higher incidence of microvascular invasion (P=0.013). More patients exceeded the Milan criteria (75.0% vs. 31.3%, odds ratio [OR] 6.60, 95% confidence interval [CI] 1.45–4.05, P=0.008) and had a rising NAS (58.3% vs. 26.3%, OR 3.20, 95% CI 1.11–9.22, P=0.024) among the recurrence group. NAS was also a strong predictor of microvascular invasion (P=0.040). After correcting for age and sex, both a rising NAS (OR 3.98, 95% CI 1.01–15.81, P=0.039) and nonadherence to Milan criteria (OR 5.69, 95% CI 1.14–28.38, P=0.034) were strong predictors of recurrence after OLT. Conclusion The NAS is a predictor of microvascular invasion, a finding exclusive to pathology and in itself a predictor of HCC recurrence after OLT. The NAS and Milan criteria are good predictors of recurrence. These results encourage a frequent monitoring of AFP variations before OLT.

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