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A Barrientos

Publications and source records attributed to A Barrientos.

At least 19 recordsLinked to original sources
PubMed2006

The perfusion pressure in non-heart-beating donors may expand the glomeruli.

INTRODUCTION: We have observed expanded glomeruli in biopsies of kidneys from non-heart-beating donors (NHBDs). We sought to determine the differences in glomerular size between NHBDs and brain-dead donors and to assess whether glomerular size impacted graft outcome. METHODS: We estimated the glomerular area using the maximal planar area (MPA) method in 198 pretransplant biopsies from 119 donors: 54 (45.4%) NHBDs and 65 (54.6%) brain-dead donors. Donor data and graft outcomes were correlated with MPA and percentage of glomerulosclerosis. The range of follow-up was 1 to 3 years. Uni- and multivariate analyses were performed. RESULTS: MPA was larger among NHBDs. MPA and GS both significantly correlated with donor age. The association between MPA and age was independent of nephron loss (ie; GS). Increased glomerular size was only observed among donors younger than 50 years. Graft survival and function were not independently associated with MPA. Donor age was a better predictor of graft outcome. CONCLUSIONS: The perfusion pressure used in NHBDs may expand the glomeruli, but this maneuver does not have any effect on graft outcome. Among donors without severe changes, glomerular size increment shows a limit around the sixth decade of life. In our study, MPA was not an independent predictor of graft survival or function.

Adolescent↗
PubMed2006

Varicella infection in adult renal allograft recipients: experience at one center.

Disseminated varicella-zoster virus (VZV) infection in adult renal allograft recipients is a rare but potentially fatal illness. We retrospectively collected the cases of VZV infection that occurred in 812 adult renal transplant recipients, performed between 1995 and 2004 at our institution. Eight patients developed varicella (1%), seven men and one woman. The overall median age was 38 years (range = 31 to 64). The median time from transplantation to infection was 32 months (range = 2 to 92). Four cases were primary infections and four disseminated VZV reactivations. Immunosuppression consisted of prednisone (PDN) + cyclosporine (CSA) + mycophenolate (MF; n = 4); PDN + CSA + azathioprine (n = 1); PDN + tacrolimus (FK) + MF (n = 1); FK + MF (n = 1); PDN + rapamycin + MF (n = 1). Seven patients (87%) required hospital admission for a median duration of 11 days (range = 3 to 21). Four patients were previously diagnosed with chronic hepatitis virus infection: two type B (HBV) and two type C (HCV). The last cohort required longer admission than the negative patients (11.5 +/- 3 vs 7.5 +/- 9 days; P = .1). The only clinical manifestation in four patients was general malaise, fever, and a disseminated vesicular rash; the other four patients also showed visceral involvement: two pneumonitis, one hepatitis, and thrombotic microangiopathy, and one developed multiorgan failure and died due to a delayed diagnosis in a patient positive for HBVs. The diagnosis was established according to the symptoms, IgG-IgM seroconversion and VZV polymerase chain reaction quantification in vesicle contents. Treatment consisted of reduced immunosuppression, antiviral drugs (acyclovir or gancyclovir), and in six patients, a varicella-zoster immunoglobulin dose. We concluded that varicella infection in adult renal allograft recipients is unusual but highly morbid. A vaccination program in seronegative pretransplant candidates should be attempted. Early diagnosis and treatment may improve the prognosis. Although further studies are required, chronic HBV or HCV infection seemed to be a risk factor for the disease.

Adult↗
PubMed2006

Conversion to sirolimus in renal transplant patients with tumors.

BACKGROUND: Conversion from calcineurin inhibitors (CNI) to sirolimus (SRL) is an option for renal transplant patients who develop a tumor. This strategy, however, may be associated with an increased risk of rejection. AIM: We sought to evaluate a series of renal transplant patients who underwent conversion from CNI to SRL because they developed a tumor during the posttransplant period. METHODS: This prospective study of 29 patients included 2 patients with skin cancer (1 melanoma and 1 squamous cell carcinoma) and 27 patients who developed other tumors: lung (n = 6), prostate (n = 4), lymphoma (n = 2), colon adenocarcinoma (n = 2), kidney (n = 2), Kaposi sarcoma (n = 2), urothelium (n = 1), parotid (n = 1), larynx (n = 1), gastric (n = 1), breast (n = 1), tongue (n = 1), liver (n = 1), xanthoastrocytoma (n = 1), and aggressive angiomyxoma of the perineum (n = 1). RESULTS: CNI were withdrawn in 28 patients and reduced in the remaining patient. Renal function was better when CNI were rapidly or abruptly suspended, with maintenance of cyclosporine (CsA) + SRL for more than 3 months being especially detrimental. Proteinuria worsened in patients whose preconversion levels were >0.5 g/d, particularly those treated with CsA. There was no episode of rejection. CONCLUSIONS: SRL is a promising option for the management of posttransplant tumors. The switch in immunosuppression should be undertaken quickly, especially in patients under treatment with CsA.

Creatinine↗
PubMed2006

Renal transplant patients with gastrointestinal intolerability to mycophenolate mofetil: conversion to enteric-coated mycophenolate sodium.

The introduction of mycophenolate mofetil (MMF) was an important advance in immunosuppressive therapy, although its use is limited by adverse gastrointestinal events. Enteric-coated mycophenolate sodium (EC-MPS; myfortic) has been developed to avoid these side effects. Recent clinical trials have demonstrated that EC-MPS is a safe drug in both de novo and maintenance renal transplant patients. In this prospective study, therapeutically equivalent doses of EC-MPS were administered to 39 stable kidney transplant patients receiving MMF. After 3 months of treatment with EC-MPS the incidence of adverse gastrointestinal events was lower (15.8% of the patients). There were higher levels of mycophenolic acid after conversion to EC-MPS, probably due to better absorption. These factors allowed decreased doses and levels of calcineurin inhibitors without increasing the risk of graft rejection. At 3 months postconversion, serum creatinine improved from the mean baseline value of 1.83 +/- 0.12 mg/dL to 1.70 +/- 0.10 mg/dL. In conclusion, EC-MPS was well tolerated in maintenance renal transplant patients with adverse gastrointestinal events secondary to MMF.

Creatinine↗
PubMed2006

Conversion to everolimus in kidney transplant recipients: a safe and simple procedure.

To date there is a substantial experience with rapamycin conversion in stable renal transplant recipients with respect to the procedure of conversion, initial doses, and target blood levels as well as adverse events, but in the case of Everolimus there is almost no experience with conversion and calcineurin inhibitor (CNI) withdrawal. We describe an initial experience among 32 renal transplant recipients who were converted to Everolimus with complete suspension of CNI in two Spanish transplant centers. Our results emphasised the procedure for conversion, the target levels, the adverse events, and the initial efficacy, over the first month after conversion. Our conclusions were that conversion from CNI to Everolimus was a simple, safe procedure with a predictable profile of adverse events, which were, in general, of mild intensity. There was a good correlation between initial dose and blood level. Initial doses of about 3 mg/d combined with rapid reduction in CNI exposure seemed to be adequate. The target range levels between 5 and 10 ng/mL seemed to be sufficient for complete CNI elimination, especially in patients also receiving antiproliferative drugs (such as mycophenolate mofetil or azathioprine) in whom levels near the lower end of the range might be adequate.

Calcineurin Inhibitors↗
PubMed2006

Involvement of endothelium and endothelin-1 in lead-induced smooth muscle cell dysfunction in rats.

Lead exposure induces dysfunction of the cyclic guanosine monophosphate-dependent vasodilator system through downregulation of soluble guanylate cyclase (sGC) expression. The endothelium not only releases vasodilators but also vasoconstrictors such as endothelin-1 (ET-1). Our aim was to explore the role of the vascular endothelium and ET-1 as possible mediators of lead-induced downregulation of sGC. Isolated aortic segments from Wistar Kyoto rats were incubated in the presence or absence of lead (1 parts per million) for 24 h. Endothelium was mechanically removed in some of the aorta segments. As reported previously, lead exposure induced downregulation of sGC protein expression in the intact aortic segments. However, lead exposure failed to significantly modify sGC-beta1 subunit expression in the endothelium-denuded aortic segments. Incubation with a selective ETA-type receptor inhibitor, BQ-123 (10(-6) mol/l), restored sGC protein expression in lead-exposed intact aortic segments. As it has also been previously observed, incubation in lead-containing medium resulted in the upregulation of cyclooxygenase-2 (COX-2) in the intact aortic segments. Denudation of endothelium partially abrogated this effect of lead. Incubation with BQ-123 prevented the lead-induced upregulation COX-2 in the intact aortic segments. However, neither ET-1 content nor ETA-type receptor expression were modified by lead exposure of the aortic segments. As conclusion, the endothelium through the activation of ETA-type receptors mediates the downregulation of sGC expression by lead in the vascular wall.

Animals↗
PubMed2006

[Rapid recurrence of ANCA-MPO positive vasculitis after non-heart beating donor renal transplantation].

We report a patient with end stage renal disease with lesions compatibles with renal vasculitis antineutrophil cytoplasmic autoantibody (ANCA)-associated in phase of sclerosis that underwent renal transplantation from a non-heart beating donor after one year of haemodialysis treatment, without evidence of active vasculitis. Post-transplantation management was performed according to our protocol in this kind of donors with immunosuppressive treatment based on daclizumab, half-doses of tacrolimus, mycophenolate mofetil and steroids. In the third week the renal biopsy showed an acute necrotizing vasculitis associated with crescent glomerulonephritis. The patient was initially diagnosed of acute vascular rejection and initiated treatment with 6-metilprednisolone and anti-CD3 monoclonal anti-bodies. Two days later he developed a cutaneous purpura and the skin biopsy showed an acute necrotizing vasculitis. The determination of circulating ANCA-anti-myeloperoxidase (MPO) was positive. We initiated treatment with oral cyclophosphamide plus mycophenolate mofetil discontinuation with rapid improvement of cutaneous lesions and initiation of renal function recovery.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2005

Association of the genetic polymorphisms of the renin-angiotensin system with kidney graft long-term outcome: preliminary results.

Recent studies have demonstrated some association between the renin-angiotensin system (RAS) activity and the development and progression of different entities as diabetes mellitus (DM) or chronic allograft nephropathy. To investigate these associations, we studied some gene polymorphisms of RAS in a group of renal transplant recipients. We retrospectively analyzed 42 patients who underwent a primary renal transplantation for 2 years. A subgroup of 23 patients (55%) was diagnosed with postransplant DM in accordance with American Diabetes Association 2001 criteria. We studied two RAS gene polymorphisms: the angiotensin-converting enzyme insertion/deletion (ACE I/D) and angiotensinogen (AGTM235T). Genotyping was performed by DNA purification and amplification with a polymerase chain reaction technique. The distributions of genotypes were ACE DD, ID, II: 33%, 48%, 19%; and AGT TT, MT, MM: 15%, 45%, 40%, respectively. We observed a progressive loss in renal function measured by creatinine clearance (Cockroft) in D-allele carriers (DD+ID) between the first and the second transplantation year: 65.3 +/- 4.3 vs 59.8 +/- 4.6 mL/min (P = 0.02); that was not seen in II patients: 68.8 +/- 4.6 vs 68.4 +/- 4 mL/min (P = 0.87). Fifty percent of D-allele carriers developed DM vs 25% of non-D-allele carriers (P = 0.19). Eighty-three percent of homozygous patients for the AGT-TT allele developed DM vs 35% of non TT patients (P = 0.04). There were no significant differences regarding recipient demographic characteristics, type of donor, number and severity of acute rejections, and immunosuppressant treatment between the groups. In conclusion, ACE D-allele seems to be associated with a poorer kidney graft long-term outcome. ACE D and AGT T alleles may be implicated in glucose metabolism disorders after transplantation.

DNA↗
PubMed2004

[BK virus in kidney allografts: a search for histologic evidence of the infection].

BACKGROUND: BK virus (BKV) associated interstitial nephritis is a complication in renal transplantation recipients. Its incidence is controversial. The aim of the present study is to determine the incidence of histopathologic evidence of BKV-infection in a single centre. MATERIALS AND METHODS: Renal allograft tissue samples (n = 838) from 526 patients undergoing renal transplant were evaluated by light microscopy. Polymerase chain reaction (PCR) assay for BKV DNA was performed in 41 microdissected cell populations from cases with viral inclusions, cases with other nuclear changes, and cases without nuclear changes. RESULTS: Polyomavirus-inclusions were identified in six cases (five with interstitial nephritis and other one with only urothelial infection). In one case with interstitial nephritis the DNA was degraded. PCR confirmed BKV infection in the other five and was negative in cases without inclusions. CONCLUSIONS: Five patterns of inclusions bodies are observed and they appear to be characteristic. PCR assay seemingly have a high specificity for BKV detection and it does not usually detect latent viral infection.

Adult↗
PubMed2003

Daclizumab induction as an immunosuppressive regimen for renal transplant recipients from non-heart-beating donors.

BACKGROUND: Recent reports have demonstrated the efficacy of interleukin-2-receptor blockers in lowering the incidence of early acute rejection. The present study aimed to test the hypothesis that the use of daclizumab induction (DAC) plus low-dose tacrolimus, mycophenolate mofetil, and steroid diminishes the incidence of delayed graft function (DGF) in renal transplants from non-heart-beating donors (NHBD). METHODS: We compared the incidence of DGF and rejection in 185 renal transplants from NHBD treated as follows: Group-I: quadruple sequential therapy with antithymocyte globulin, cyclosporine, azathioprine, and steroids (n=22); Group-II: cyclosporine (8 mg/kg/d) plus azathioprine plus steroid (n=26); Group-III: low-dose cyclosporine (5 mg/kg/d) plus mycophenolate mofetil plus steroid (n=68); Group-IV: low-dose tacrolimus (0.1 mg/kg/d) plus mycophenolate mofetil plus steroid (n=17); and Group-V: DAC plus low-dose tacrolimus plus mycophenolate mofetil plus steroid (n=43). RESULTS: The incidences of DGF were 72.7% in Group-I, 73.1% in Group-II, 69.1% in Group-III, 76.5% in Group-IV, and 44.2% in Group-V. Acute rejection was higher in Group-IV. CONCLUSIONS: The combination of DAC, low-dose tacrolimus, mycophenolate mofetil, and steroids is effective in lowering the incidence of DSF in NHBD kidney transplant recipients without any increase in acute rejection.

Adrenal Cortex Hormones↗
PubMed2002

Pulmonary diffusing capacity in chronic dialysis patients.

Patients with end-stage renal disease treated by hemodialysis with bioincompatible membranes are exposed during the dialysis period to acute effects on lung microcirculation, which may result in pulmonary fibrosis and diffusion defects in long-standing dialysis. To investigate the occurrence of these possible chronic pulmonary alterations, we determined lung function in patients with chronic renal failure not undergoing hemodialysis and in patients who had been receiving regular hemodialysis both for short and long periods of time. Forty-three patients divided into three groups were studied: 17 patients before dialysis with a mean (SD) creatinine clearance of 14.1 (6.8) ml/min 11.73 m2, 10 patients receiving regular hemodialysis for a period of less than 12 months (mean 6.4 +/- 3.5 months), and 16 patients receiving regular hemodialysis for more than 5 years (mean 8.3 +/- 3.6 years). First-use bioincompatible cellulosic dialysis membranes were used in all the cases. The following parameters were recorded: forced vital capacity (FVC), forced expiratory volume in 1s (FEV1), total lung capacity (TLC), residual volume (RV), carbon monoxide transfer factor (TLCO), accessible lung volume (VA), carbon monoxide transfer factor/accessible lung volume (KCO- that is, TLCO/VA), and arterial blood gases. Patients receiving regular hemodialysis for more than 5 years showed significantly lower values of TLCO and KCO than patients before dialysis and patients receiving regular hemodialysis for less than 12 months. Seventy-five percent of patients on long-term hemodialysis had markedly reduced TLCO or KCO values (below 80% of the reference value) as compared with 17% of patients before dialysis and 10% of patients dialyzed for less than 12 months (P < 0.001). Differences among groups for the remaining parameters were not observed. In conclusion, patients undergoing long-term regular hemodialysis with a bioincompatible membrane showed a selective reduction in pulmonary diffusing capacity possibly due to chronic pulmonary fibrosis.

Aged↗
PubMed2001

In vivo regulation of oxidative phosphorylation in cells harboring a stop-codon mutation in mitochondrial DNA-encoded cytochrome c oxidase subunit I.

The mechanisms that regulate oxidative phosphorylation in mammalian cells are largely unknown. To address this issue, cybrids were generated by fusing osteosarcoma cells devoid of mitochondrial DNA (mtDNA) with platelets from a patient with a stop-codon mutation in cytochrome c oxidase subunit I (COX I). The molecular and biochemical characteristics of cybrids harboring varying levels of mutated mitochondrial DNA were studied. We found a direct correlation between the levels of mutated COX I DNA and mutated COX I mRNA, whereas the levels of COX I total mRNA were unchanged. COX I polypeptide synthesis and steady-state levels were inversely proportional to mutation levels. Cytochrome c oxidase subunit II was reduced proportionally to COX I, indicating impairment in complex assembly. COX enzymatic activity was inversely proportional to the levels of mutated mtDNA. However, both cell respiration and ATP synthesis were preserved in cells with lower proportions of mutated genomes, with a threshold at approximately 40%, and decreased linearly with increasing mutated mtDNA. These results indicate that COX levels in mutated cells were not regulated at the transcriptional, translational, and post-translational levels. Because of a small excess of COX capacity, the levels of expression of COX subunits exerted a relatively tight control on oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed2001

Does renal mass exert an independent effect on the determinants of antigen-dependent injury?

The aim of this retrospective study was to determine whether nephron mass may exert a direct, independent effect on immunological tolerance. To this end, data corresponding to patients transplanted with en block pediatric kidneys (EBPK) (n=48) were compared with those of renal transplants with a low risk of hyperfiltration (LRH) comprised of recipients of a kidney from young donors (age 5-40 years) (n=173), and transplants with a high risk of hyperfiltration (HRH) comprised of patients who had received a graft from an elderly donor (older than 55 years) (n=91). All the patients had been subjected to the same immunosuppressive treatment. The median follow-up period was 54 months (6-127 months). The EBPK group showed lowest serum creatinine and highest creatinine clearance levels at each follow-up time. The rate of proteinuria >500 mg/day was 5.7% in EBPK, 7.4% in LRH, and 27.3% in HRH (P=0.000). The incidence of acute corticoresistant rejection was minor in EBPK (7.0% in EBPK, 21.3% in LRH, and 23.3% in HRH; P=0.04). Logistic regression analysis showed that the type of transplant was predictive of acute corticoresistant rejection [RR 5.33 (95% confidence interval (CI) 1.15-24.62) for HRH and RR 4.75 (95%CI 1.06-21.27) for LRH, P=0.03]. Multivariate analyses for graft failure due to chronic rejection and for graft failure due to acute rejection according to Cox's regression analysis demonstrated that HRH transplant was a significant predictive variable of both types of failure [4.08 (95%CI 1.27-13.04) for graft loss due to chronic rejection and 8.69 (95%CI 1.69-44.67) for graft loss due to acute rejection]. The present stratification of data according to nephronal mass would appear to indicate that the greater the mass, the lower the incidence of both acute and chronic rejection. This finding lends support to the hypothesis that a large mass of transplanted tissue relative to recipient mass may dampen the immune response.

Adult↗
PubMed2001

Incidence of renal artery stenosis in pediatric en bloc and adult single kidney transplants.

BACKGROUND: The incidence, time of onset, and outcome of transplant renal artery stenosis (TRAS) in pediatric en bloc (PT) and adult single-kidney (AT) transplants were reviewed. METHODS: Forty-three cases (7 PT and 36 AT) of suspected TRAS were selected out of 367 functioning grafts (35 of them PT). Diagnosis was performed by digital subtraction arteriography. Percutaneous transluminal angioplasty (PTA) was performed when needed. RESULTS: Seven (20%) PT and 24 (7.1%) AT presented TRAS. Time of onset was 7+/-1 months in PT and 18+/-17 months in AT (P<0.05). PTA was performed in all cases of TRAS in PT and in 19 AT. One PT and 7 AT had re-stenosis. There was no significant difference in renal function after treatment. Control of blood pressure improved in both groups. CONCLUSIONS: Recipients of PT grafts showed a higher incidence and earlier onset of TRAS. Re-stenosis was more frequent in AT.

Adolescent↗