Alberto Barrientos

Evaluation of fluorescent dyes for the detection of mitochondrial membrane potential changes in cultured cardiomyocytes

OBJECTIVE Maintenance of the mitochondrial membrane potential (Deltapsim) is fundamental for the normal performance and survival of cells such as cardiomyocytes, that have a high energy requirement. Measurement of Deltapsim is therefore essential in order to develop an understanding of the molecular mechanisms controlling cardiomyocyte function. Here we have evaluated various potentiometric dyes for their ability to detect alterations of Deltapsim, using flow cytometry and confocal microscopy. METHODS Primary cultures of cardiomyocytes from neonate rats were treated with mitochondrial uncouplers before or after loading with Rho123, DiOC(6)(3), CMXRos or JC-1, and then analysed by flow cytometry. Apoptotic cells were identified by light scatter and Annexin V staining. RESULTS The four potentiometric dyes tested were able to discriminate between viable and apoptotic cells. However, only JC-1 was able to detect the collapse of Deltapsim induced by uncouplers of mitochondrial respiration. Confocal microscopic analysis confirmed that JC-1 stained mitochondria in a potential-dependent manner. In contrast, CMXRos stained cardiomyocytes irrespective of alterations in Deltapsim. CONCLUSIONS We conclude that JC-1 is the optimal dye to use when measuring Deltapsim in cardiomyocytes.

Cardiovascular effects of recombinant human erythropoietin in predialysis patients

Treatment with recombinant human erythropoietin (rHuEPO) has solved the problem of anemia in patients on dialysis. However, its application to predialysis patients has raised some doubts about its effects on the progression of renal disease and on blood pressure (BP) and hemodynamic regulation. We have prospectively studied over at least 6 months a group of 11 predialysis patients receiving rHuEPO treatment (initial dose, 1,000 U subcutaneously three times a week). Clinical assessment and biochemical and hematologic measurements were made once every 2 weeks. Twenty-four-hour ambulatory BP monitoring, echocardiography, and determination of neurohumoral mediators of hemodynamics were performed once every 3 months. An adequate hematologic response was found (hemoglobin, 11.7 +/- 0.4 g/dL v 9 +/- 0.3 g/dL) without changes in the progression of renal disease. A decrease in cardiac output and an increase in total peripheral resistance was seen as anemia improved. A trend toward decreased left ventricular (LV) thickness and a significant decrease in LV mass index (from 178.2 +/- 20.6 g/m2 to 147.3 +/- 20.6 g/m2) were observed. Blood pressure control did not improve; moreover, in some patients an increase in systolic values was detected by ambulatory BP. Casual BP remained seemingly stable. Sequential determinations of neurohumoral mediators of hemodynamic substances (endothelin, renin, norepinephrine, epinephrine, dopamine) failed to explain these results. Ambulatory BP reveals a worse control in some patients who were previously hypertensive and confirms the utility of this technique in the assessment of patients under erythropoietin treatment. The trend toward LV hypertrophy regression without improved BP control confirms the role of anemia among the multiple factors leading to LV hypertrophy in end-stage renal disease (ESRD), and opens therapeutic possibilities. Better control of BP may avoid a potential offsetting of beneficial effects that correcting anemia would have on the cardiovascular system.

Victims of Cardiac Arrest Occurring Outside the Hospital: A Source of Transplantable Kidneys

Context Waiting lists for kidney transplants are long. Contribution This study from Madrid, Spain, compared transplantation outcomes of 584 recipients of kidneys from heart-beating donors and 320 recipients of kidneys from nonheart-beating donors who died of cardiac arrest that occurred outside the hospital. One-year (about 90%) and 5-year (about 85%) graft survival rates were similar for transplantations from nonheart-beating donors and those from heart-beating donors who were younger than 60 years of age. Cautions This retrospective study is from a center with a well-developed nonheart-beating donor transplantation program. Implications People who die of cardiac arrest that occurs outside the hospital can be a viable source for kidney transplantations. The Editors The waiting list and waiting time for transplantations will inevitably become longer as the demand for kidneys continues to exceed the supply. The kidney waiting list of the United Network for Organ Sharing currently increases at a rate of 20% per year, and the list will be 100000 to 150000 patients long by the year 2010 (1). The overall annual mortality rate for wait-listed patients for kidney transplants is estimated to be 6.3% (2). While obtaining more organs from brain-dead donors with heartbeats is necessary, additional sources of organs are also needed, which has prompted the use of the nonheart-beating donor. Nonheart-beating donors are categorized into 5 types (Appendix Table) (3). Type I and type II are considered uncontrolled donors because cardiac arrest events in these patients occur outside the hospital and, thus, the transplant team is unaware of them. In type III and type IV nonheart-beating donors, cardiac arrest is managed, or controlled, in the hospital, and the transplant team can prepare for the procurement process. In type V nonheart-beating donors, this aspect can vary. Several reports have discussed the use of nonheart-beating donors (424), and the incidence of this type of donation is increasing. However, most patients described in these studies have in-hospital cardiac arrest, and few references have been made to donors whose deaths occur outside the hospital. Appendix Table. Description of the NonHeart-Beating Donor Types (Maastricht System) In 1989, our institution (Hospital Clnico San Carlos, Madrid, Spain) began a nonheart-beating donor procurement and transplant program. Our hospital is currently the largest procurement center for this type of transplantation in Spain, supplying 46% of the nonheart-beating donor kidneys transplanted in Spain in 1997 (3, 25). Most of our donors are adults who die suddenly outside the hospital and are transferred to the hospital for the sole purpose of donation (Maastricht type I donors) (26). We aimed to compare the graft survival of kidneys from uncontrolled nonheart-beating donors (Maastricht donors type I and II) and kidneys from heart-beating donors. Methods Donor Program In 1989, our hospital started a program to obtain organs from nonheart-beating donors (3). In 1996, we signed a formal agreement with the Madrid emergency facilities (SAMUR, 061, SERCAM) and established a standard protocol for obtaining organs from persons who die suddenly outside the hospital of irreversible cardiac arrest (type I Maastricht donor category) and are transported to our center for organ donation. Before 1996, most of these persons were directly transported to the morgue, but after 1996, patients were transferred to our hospital after unsuccessful cardiovascular pulmonary resuscitation (CPR). This protocol does not affect any CPR maneuver. All measures and times specified in the established CPR procedures are undertaken, and we evaluate the patient as a potential donor only when the cardiac arrest is considered irreversible (when an effective heartbeat cannot be recovered after a stipulated period [usually 30 minutes] or when the lesions provoking the cardiac arrest are incompatible with life). The following conditions should also be met when considering a potential donor: known cause of death, ruling out violence; known time of cardiac arrest; no bleeding injuries to the thorax or abdomen to avoid blood leaks in subsequent cardiopulmonary bypass during procurement; external cardiac massage and mechanical ventilation performed within 15 minutes of the cardiac arrest; no external signs of possible intravenous drug abuse suggesting a risk for HIV, hepatitis C, or hepatitis B infection; and donor age less than 60 years. When an individual has been classified as a potential donor, the emergency team continues with cardiac massage, mechanical ventilation, and intravenous fluid perfusion to maintain adequate hemodynamic conditions during transport to our hospital. Upon arrival, the transplant coordination team checks for the conventional prerequisites for donation (for example, no infections; negative results on serologic tests for HIV and hepatitis B and C; and no tumors) and then transfers the cadaver to the operating room. In type I and type II nonheart-beating donors, the femoral vein and artery are cannulated via an incision in the right side of the groin and are connected to a cardiopulmonary bypass machine with external oxygenation and hypothermia. The maximum time of warm ischemia (from the start of cardiac arrest until bypass) should not exceed 120 minutes. Maximum pump cold perfusion time is 240 minutes. While the organ is being perfused, the transplant coordination team fulfills the legal requirements for donation. The first step is to locate the family of the deceased person and obtain consent for organ extraction. Organ retrieval is performed according to the Maastricht protocol, which requires a diagnosis of death by physicians independent of those of the procurement team and a procurement protocol approved by the local medical ethics committee according to the current organ procurement legislation. Since 1999, Spain has had a law (Real Decreto 2070/1999) that allows organ donation after cardiac arrest. Under this law, the donor can undergo cardiopulmonary bypass until the necessary consent is obtained for organ extraction. In the past year, only 7% of families declined consent for organ extraction. Study Design and Sample From January 1989 to December 2004, our center transplanted 342 kidneys from nonheart-beating donors. According to the modified Maastricht donor classification scheme (3), these graft donors are classified as follows: 273 (79.8%) type I donors (dead on arrival), 47 (13.7%) type II donors (unsuccessful resuscitation in the emergency department), 6 (1.8%) type III donors (cardiac arrest in intensive care), 4 (1.2%) type IV donors (cardiac arrest during or after a diagnosis of brain death), and 12 (3.5%) type V donors (unexpected cardiac arrest in intensive care). In our retrospective study of procedures at our center, we compared data from 320 recipients of kidneys from uncontrolled, nonheart-beating donors (type I or type II Maastricht donor category) with those from 584 recipients of kidneys from adult cadaveric heart-beating donors between January 1989 and December 2004. We divided the heart-beating donor transplants into 2 groups according to donor age: younger than 60 years of age (n= 458) and 60 years of age or older (n= 126). Figure 1 shows data on the transplantations performed per year. We excluded transplantations from types III, IV, and V nonheart-beating donors and those from heart-beating donors other than adult cadaveric donors (en bloc pediatric renal transplantations or double renal transplantations from older donors). Figure 1. Kidney transplantations at the Hospital Clnico San Carlos, Madrid, Spain, January 1989December 2004. Other transplantations are those involving other than single adult cadaveric heart-beating donors (en bloc pediatric renal transplantations or double renal transplantations from donors 60 years of age) and those involving types III, IV, and V nonheart-beating donors. Treatment and Outcome Measures We treated transplant recipients with quadruple sequential therapy (antithymocyte globulin for 7 days, azathioprine, prednisone from the time of transplantation, and cyclosporine from day 5) from January 1989 to July 1996. From July 1996 to March 2001, the immunosuppression regimen used was triple therapy with cyclosporine or tacrolimus (plus prednisone and mycophenolate). After March 2001, recipients of kidneys from nonheart-beating donors and from heart-beating donors 60 years of age or older received daclizumab and a half-dosage of tacrolimus (0.1 mg/kg of body weight per day to achieve trough levels between 5 ng/mL and 8 ng/mL) during the first 2 weeks to avoid delayed graft function, whereas recipients of kidneys from heart-beating donors younger than 60 years of age did not receive daclizumab and were treated with full-dosage tacrolimus (0.2 mg/kg per day to achieve trough levels between 8 ng/mL and 12 ng/mL). The dosages of mycophenolate and steroids were similar for the 3 groups. Hyperimmunized patients (preformed reactive antibodies 50%) were treated with the monoclonal antibody muromonab-CD3 or antithymocyte globulin. We defined delayed graft function as the need for dialysis during the immediate post-transplantation period. Patients who showed delayed graft function underwent a biopsy every 7 days until renal function started to improve. We graded acute rejection according to the Banff 97 classification (27). We treated grade I rejection (interstitial infiltration and tubulitis) with high doses of pulse steroids. We treated grade II (intimal arteritis) or grade III (transmural arteritis) rejection with either muromonab-CD3 or antithymocyte globulin. Our policy is to discharge patients when graft function starts to improve. Subsequent ambulatory patient management does not vary according to donor type. The end point of the study was graft loss, defined as nephrectomy, retransplantation, or permanent return to dialysis. We followed pa

Lead-Induced Downregulation of Soluble Guanylate Cyclase in Isolated Rat Aortic Segments Mediated by Reactive Oxygen Species and Cyclooxygenase-2

Lead exposure is a known cause of hypertension. Although most studies have focused on lead-induced endothelial dysfunction and on the involvement of reactive oxygen species (ROS), it has been recently demonstrated that the vascular wall of lead-exposed rats has both an altered the endothelium-independent relaxing response and a reduced expression of soluble guanylate cyclase (sGC). The aim of the present study was to determine in in vitro incubated rat isolated aortic segments if lead downregulates sGC expression, analyzing the involvement of ROS and cyclooxygenase-2 (COX-2). The experiments were performed in isolated aortic segments from Wistar rats that were incubated with lead for 24 h. Lead significantly reduced sGC-beta(1) subunit expression in a concentration-dependent manner. The maximal reduction in sGC-beta(1) subunit expression was achieved with 1 ppm lead. Vitamin C (30 micromol/L) partially restored sGC-beta( 1) subunit expression in lead (1 ppm)-exposed aortic segments. A similar protection of sGC-beta(1) subunit expression was obtained with both a protein kinase A inhibitor, H89 (1 micromol/L) and with rofecoxib (1 micromol/L), an inhibitor of COX-2 activity. Moreover, lead exposure increased COX-2 expression in the arterial wall. While vitamin C reduced both COX-2 expression and superoxide anion production related to lead exposure, rofecoxib failed to modify superoxide anion generation in lead-incubated aortic segments. In conclusion, the present results suggest the involvement of ROS and COX-2 in the downexpression of sGC-beta(1) subunit induced by lead in the rat vascular wall.

Increasing the donor pool using en bloc pediatric kidneys for transplant.

Objectives. En bloc pediatric kidney transplants (EBPKT) are still a subject of controversy. The aim of this study was to determine whether acceptable long-term graft survival and function can be achieved in EBPKT compared with the transplant of single, cadaveric, adult donor kidneys. Methods. A retrospective review was conducted of 66 recipients of en bloc kidneys from cadaveric pediatric donors and 434 patients who underwent transplantation with a single kidney from an adult donor between January 1990 and May 2002 at the authors’ hospital. The recipients were well-matched demographically. Both transplant groups were analyzed for short- and long-term performance in terms of transplant outcome and quality of graft function. Results. Overall death-censored actuarial graft survival rates at 1 and 5 years were 89.2% and 84.6% in the adult kidney transplants (AKT) and 83.3% and 81.1% in EBPKT, respectively (P =0.56). In the EBPKT group, graft function was improved over that observed in AKT. Vascular thrombosis was the most common cause of graft loss in EBPKT. Acute rejection occurred more frequently in AKT and Cox’s regression analysis indicated that undergoing an AKT was a predictive factor for acute vascular rejection (adjusted risk ratio, 3.8; 95% confidence interval, 1.4–10.2; P =0.001). Conclusions. Overall graft survival was similar in both groups, vascular complications were the main cause of graft loss in EBPKT, and the EBPKT showed excellent long-term graft function and a low incidence of acute rejection.

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.

Functional glomerular reserve in recipients of en bloc pediatric transplant kidneys

BACKGROUND The transplantation of an adequate renal mass is increasingly recognized to be of importance. The improved graft survival is probably due to a lesser risk of developing hyperfiltration-associated lesions. METHODS We have reviewed the glomerular reserve in our recipients of en bloc pediatric transplant kidneys after an intravenous amino acid overload and compared them to single adult kidney transplant recipients. RESULTS En bloc transplants evidenced increased glomerular filtration rate as compared with baseline as from the second hour of amino acid infusion (from 71+/-14 to 84.9+/-17 ml/min, 1.73 m2, P<0.05) and increased renal plasma flow as from the third hour (from 335+/-116 to 402+/-155 ml/min, 1.73 m2, P<0.05). In the single adult kidney recipient group, no change was seen either in the glomerular filtration rate (from 62.5+/-13 to 58.1+/-13 ml/min, 1.73 m2, P=NS) nor in renal plasma flow (from 354+/-125 to 304+/-98 ml/min, 1.73 m2, P=NS). CONCLUSIONS These results show that patients receiving en bloc pediatric kidney transplantations have a greater renal functional reserve and show a lesser risk of hyperfiltration.

Sirolimus and Everolimus Induced Pneumonitis in Adult Renal Allograft Recipients: Experience in a Center

Mammalian target of rapamycin (mTOR) inhibitors induce pneumonitis, an unusual but potentially fatal side effect of this drug group. We retrospectively collected the cases of pneumonitis induced by sirolimus or everolimus among 1471 adult cadaveric renal transplant recipients who were grafted at our institution from 1980-2008. Due to chronic transplant dysfunction or tumor, 205 patients were switched from calcineurin inhibitors to sirolimus (n = 88) or to everolimus (n = 117). Six patients (2.9%) developed pneumonitis: 1 was associated with sirolimus and 5 with everolimus (5 males and 1 female; median age, 60 years [range, 47-73 years]). Median times from conversion to pneumonitis onset were 34 days in 4 patients (range, 24-46 days) and 491 days in 2 subjects (range, 454-528 days). The mean drug trough level at presentation was 8.2 microg/L (range, 5.5-13.8 microg/L). The most common symptoms were dry cough (n = 6), fever (n = 5), and dyspnea (n = 4). Imaging tests revealed lower lobe involvement in all patients. Bronchoalveolar lavage performed in 4 patients showed lymphocytic alveolitis. All patients completely recovered after drug withdrawal. Five patients received steroids, 5 were switched to a calcineurin inhibitor, and 1 was switched to the other mTOR inhibitor. In conclusion, mTOR inhibitor-associated pneumonitis is a rare disease. Sirolimus did not cause more cases of pneumonitis than everolimus. Pneumonitis development was not dependent upon the drug blood level. Lower lobe involvement and lymphocytic alveolitis were usually present. Discontinuation of the mTOR inhibitor with steroid prescription resulted in adequate outcomes. A change to the other mTOR inhibitor should be contemplated if patient circumstances require this type of immunosuppression.

The Prevalence of Uridine Diphosphate-Glucuronosyltransferase 1A9 (UGT1A9) Gene Promoter Region Single-Nucleotide Polymorphisms T-275A and C-2152T and Its Influence on Mycophenolic Acid Pharmacokinetics in Stable Renal Transplant Patients

UNLABELLED The aim of this study was to evaluate the distribution of UGT1A9 promoter region T-275A and C-2152T single nucleotide polymorphisms (SNPs) in stable transplant patients and to investigate the impact of these SNPs on mycophenolic acid (MPA) pharmacokinetics. METHODS In total, 133 Caucasian renal transplant recipients were studied. Also a complete 12-hour pharmacokinetic profile was recorded for 15 transplant patients who had the polymorphism and for 15 controls who were randomly chosen since they received the same type and dosage of mycophenolate, same posttransplant time and similar renal function. RESULTS The T-275A promoter mutation was detected in 12.03% of patients and the C-2152T in 9.77%. All patients with the mutation C-2152T had associated the mutation T-275A. Patients who carried either the T-275A or the C-2152T polymorphism (or both) experienced more admissions owing to gastrointestinal side effects (P < .05). The pharmacokinetics studies showed that carriers of T-275A and/or C-2152T displayed a smaller area under-concentration time curve (AUC): 57.8 +/- 4.3 vs 78.9 +/- 10.8 mg/L*h (P < .03). CONCLUSION It seemed that carriers of T-275A and C-2152T SNPs of the UGT1A9 gene promoter region in the late posttransplant recipient group, showed a greater incidence of gastrointestinal side effects and a lower MPA exposure.

Modifications by Olmesartan medoxomil treatment of the platelet protein profile of moderate hypertensive patients.

Olmesartan medoxomil is a new angiotensin II receptor blockers (ARB) which exhibits pleiotropic effects that are not fully understood. Our aims were: i) to determine the effect of Olmesartan medoxomil on blood pressure, lipid profile and renal functionality in moderately hypertensive patients with non‐controlled blood pressure, ii) to determine if Olmesartan medoxomil may exert anti‐inflammatory effects and modify the expression profile of platelet proteins. Thirteen moderate hypertensive patients with non‐controlled systolic blood pressure (SBP) and renal function classified as Kidney Disease Outcome Quality Initiative stage 2–3 were included. Patients were treated with Olmesartan medoxomil (20 mg/day) for 6 months. SBP, proteinuria and the plasma levels of cholesterol and low density lipoprotein (LDL)‐cholesterol were reduced after the treatment. Olmesartan medoxomil did not modify the circulating plasma levels of a number of proteins associated with inflammation, but reduced the expression level of different platelet proteins including tropomyosin‐β chain isotypes 3 and 4, serotransferrin isotypes 1 to 5, the leukocyte elastase inhibitor and the chloride intracellular channel‐protein isotype 1. The expression of the gelsolin precursor isotype 4 was increased in the platelets after the treatment. In summary, Olmesartan medoxomil reduced SBP, total and LDL‐cholesterol plasma levels and urinary protein excretion and induced changes in the expression of platelet proteins which may be related to some action of the drug at the megakaryocyte level.