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Biomedical subjects

Rakesh Sindhi

Publications and source records attributed to Rakesh Sindhi.

27 records · Page 2Linked to original sources
PubMed2003

Modeling individual variation in biomarker response to combination immunosuppression with stimulated lymphocyte responses-potential clinical implications.

BACKGROUND: In mitogen-stimulated lymphocyte responses (sLR), cytokines and cell-surface receptors in peripheral human blood lymphocytes (PBL) are sensitive to cyclosporine (CsA), and can predict its in vivo effect with pharmacodynamic (PD) modeling. This is not known for multiple-agent combinations. METHODS: Twenty-five concentration mixtures of CsA (0-1200 ng/ml) plus sirolimus (SRL, 0-30 ng/ml) were added to whole blood from five normal human subjects (NHS) for effect on a limited array of six targets. Effect-concentration relationships were analyzed with E(max) PD equations, and expressed as the range of concentration mixtures associated with one-half of maximal inhibitory effect (EC(50)) on a model biomarker target. This predicted range was examined to see whether it contained representative concentration mixtures of these two drugs, which were associated with a stable post-transplant outcome in a logistic regression model of 1039 clinical trial patients. RESULTS: PD analyses suggested that in NHS samples containing CsA+SRL (n=5), (1) PMA-Ionomycin-stimulated T-cell expression of intracellular IL-2, TNF-alpha, and IFN-gamma was inhibited by CsA, and minimally by SRL, and (2) the two agents inhibited pokeweed mitogen (PWM)-stimulated B-cell expression of CD54 and CD95, but not CD86 (ICAM-1, Fas antigen, and B7.2), synergistically. With CD54 as the model biomarker, contour plots also predicted a wide range of concentration mixtures of the two agents across which an EC(50) could be predicted for CsA+SRL in a population (e.g., CsA-72 ng/ml+SRL 15 ng/ml, n=5), as well as in the individual subject (e.g., CsA-0 ng/ml+SRL-13.75 ng/ml in NHS-D310). Logistic regression analysis of clinical outcomes in 1039 patients suggested that the concentration mixture of CsA congruent with 50-150 ng/ml+SRL congruent with 10 ng/ml was associated with a stable post-transplant course. The EC(50) contour plot for CD54 suggested a nearly identical CsA concentration of 120 ng/ml in the presence of 10 ng/ml of sirolimus. CONCLUSIONS: Our data suggest that pharmacodynamic evaluation of immunosuppressive agents with biomarkers may be an efficient process with which to characterize immunosuppressive effect of combination agents in individual patients and in patient populations.

Biomarkers↗
PubMed2003

Liver transplantation in children with cystic fibrosis: a long-term longitudinal review of a single center's experience.

BACKGROUND: Improved long-term survival in cystic fibrosis (CF) has led to an increased incidence of extrapulmonary complications of this disease. Of these, end-stage liver disease is a significant cause of morbidity and mortality with liver transplantation being the only effective therapy. METHODS: Records of all CF pediatric liver transplant recipients were reviewed. RESULTS: Twelve children with CF were the recipients of 16 allografts. The 1- and 5-year survival was 91.6% and 75%, respectively. There were 5 deaths at a mean interval of 6.8 +/- 6.3 years. All of these deaths were related to pulmonary disease. Pulmonary function improved or remained stable in 8 of 9 patients tested. Despite an 83% incidence of positive sputum cultures, there was only one early mortality related to pulmonary sepsis in the setting of primary liver allograft nonfunction. CONCLUSIONS: Liver transplantation is acceptable treatment for children with CF and end-stage liver disease. Long-term survival is comparable to liver transplantation performed for other indications. Although posttransplant morbidity and mortality is related to lung disease, the authors speculate that as therapeutic improvements prolong the survival in CF, it is expected that longer survival after liver transplantation in this patient population may also be anticipated.

Adolescent↗
PubMed2003

Lymphocyte subsets may discern treatment effects in children and young adults with post-transplant lymphoproliferative disorder.

To identify potential alternatives to Epstein-Barr virus (EBV)-specific cytotoxic T-cell responses, peripheral lymphocyte subsets (PLS) (CD4+, CD8+, CD3+, CD19+, CD56+) were measured by flow cytometry in children with abdominal transplants (n = 22) and heart transplants (n = 2), with (n = 14) and without (n = 10, group C) post-transplant lymphoproliferative disorder (PTLD). PTLD resolved with reduced immunosuppression and antiviral therapy in eight children (group B). Recalcitrant PTLD was observed in six children (group A). Recalcitrant PTLD followed prior antilymphocyte therapy [monoclonal anti-CD3 antibody (OKT3) and thymoglobin (n = 3) and thymoglobin (n = 1)] for refractory rejection in four of these six children, and resolved after treatment with rituximab (anti-CD20 monoclonal antibody). Ten children without PTLD served as a control group (group C). Between group comparisons showed a numeric increase in CD8 + cells and significantly lower CD4:CD8 ratios in both PTLD groups (A and B) compared with group C. Group A children also demonstrated significant depletion of natural killer (NK) cells, and post-rituximab depletion of B-cells compared with group B (no rituximab treatment). We conclude that NK cell depletion with a reversed CD4:CD8 ratio may represent a persistent immunosuppressed state, which may result from prior antilymphocyte therapy and may predispose to recalcitrant EBV-PTLD. Clinical remission with rituximab is accompanied by B-cell depletion. Serial monitoring of PLS from the time of diagnosis of PTLD will be necessary to confirm these observations.

Adolescent↗
PubMed2003

Liver and intestinal transplantation in a child with cystic fibrosis: a case report.

Cystic fibrosis (CF) is an inherited disorder that presents as a multisystem disease with meconium ileus being the presenting symptom in 20% of patients. Approximately half of these patients present with complicated meconium ileus mandating early surgical intervention, potentially resulting in short gut syndrome. Although liver transplantation in children with CF has been described, this is the first report of a combined liver and small bowel transplant in a recipient with CF. A 7-month-old boy with CF presented with short bowel syndrome following extensive small bowel resection for meconium ileus and progressive cholestatic liver failure from intravenous hyperalimentation. He underwent combined liver and small intestinal transplant. He was discharged home three weeks post-transplant on enteral feeds with supplemental intravenous fluid. He has had routine protocol small bowel allograft biopsies with no documented rejection episodes. He has been treated for minor respiratory infections without major sequelae. Improvements in pulmonary therapy have impacted on the survival in the CF population to the point where the need for multiorgan transplantation will be increased in the future. Extrapolating from the excellent experience of liver transplantation in children with CF, early liver and small intestinal multivisceral transplantation, if indicated, can be performed safely in children with CF.

Cystic Fibrosis↗
PubMed2002

Causes of mortality beyond 1 year after primary pediatric liver transplant under tacrolimus.

BACKGROUND: Success of pediatric liver transplantation has improved significantly. Most posttransplant deaths occur early and are related to surgical complications or recipient status at the time of transplantation. The causes of mortality beyond the first year have not been well described. METHODS: Three hundred twenty-six pediatric liver transplants were performed between November 1989 and April 1998 using tacrolimus-based immunosuppression. Patients were followed until March 2002. Mean follow-up was 9.2+/-2.4 years. RESULTS: At 1 year, 279 patients (85.5%) were alive. In the subsequent 12.5 years, 10 of the remaining children died (3.58%) at a mean interval of 3.68+/-1.69 years after transplant. The mean age at transplant was 5.62+/-6.3 years. Six patients had infections as a major contributor to mortality, including two patients with posttransplant lymphoproliferative disorder (PTLD) and one patient that died after retransplantation for hepatitis. Two patients had recurrent malignancy. Other deaths were attributable to chronic rejection, liver failure after being lost to follow-up, and complications of cystic fibrosis. CONCLUSIONS: Pediatric liver transplantation using tacrolimus-based immunosuppression has demonstrated excellent success, with 1- and 10-year survival rates of 85.5% and 82.9%, respectively. Late mortality after pediatric liver transplantation overall remains low, with a rate of 0.32% per year. The most common cause of death was infection (60%), including PTLD-related disease (20%). However, in the recent cohort of patients who underwent transplantation after September 1995, there were no fatal cases of Epstein-Barr virus or PTLD or late mortality thus far, suggesting a benefit from improved infectious disease surveillance using currently available modalities. Mortality from chronic rejection and noncompliance under tacrolimus has been exceedingly rare.

Cause of Death↗
PubMed2002

Posttransplant lymphoproliferative disorders in liver transplantation: a 20-year experience.

OBJECTIVE: To evaluate the incidence of posttransplant lymphoproliferative disease (PTLD) and the risk factors and the impact of this complication on survival outcomes in a large cohort of liver transplant recipients at a single institution. SUMMARY BACKGROUND DATA: Liver transplantation has been accepted as a therapeutic option for patients with end-stage liver disease since 1983, in large part due to the availability and reliance on the use of nonspecifically directed immunosuppression. However, as predicted and subsequently verified in 1968, an increased incidence of certain de novo malignancies has been observed, particularly with regards to lymphoid neoplasms. While many reports have confirmed and clarified the nature of PTLD, the literature is fraught with conflicting experience and outcomes with PTLD. METHODS: Four thousand consecutive patients who underwent liver transplants between February 1981 and April 1998 were included in this analysis and were followed to November 2001. The effect of recipient age at the time of transplant, recipient gender, diagnosis, baseline immunosuppression, grading of PTLD, and association with Epstein-Barr virus were compared. The causes of death were also examined. Treatment for PTLD varied over the 20-year period, but all included massive reduction or elimination of baseline immunosuppression. RESULTS: The 1-year patient survival for liver transplant patients with PTLD was 85%, while the overall patient survival for the entire cohort was 53%. The actuarial 20-year survival was estimated at 45%. The overall median time to PTLD presentation was 10 months, and children had an incidence of PTLD that was threefold higher than adults. Patient survival was better in children, in patients transplanted in the era of tacrolimus immunosuppression, in patients with polymorphic PTLD, and in those with limited disease. Interestingly, neither the presence or absence of Epstein-Barr virus nor the timing of PTLD presentation appeared to influence overall patient survival. Patients transplanted for alcohol-related liver disease had a similar incidence of PTLD but had a higher risk of mortality. CONCLUSIONS: While PTLD continues to pose problems in patients receiving liver transplants, improvements in patient survival have been observed over time. While it is too early to assess the impact of new advances in prophylaxis, diagnosis, and treatment, such approaches are based on an increased knowledge of the pathophysiology of PTLD.

Adult↗