Cystatin C and renal function in pediatric kidney transplant recipients

In clinical practice, the glomerular filtration rate (GFR) is often determined with serum creatinine. However, studies have shown cystatin C to be a better parameter for the diagnosis of impaired renal function. We compared GFR estimated by plasma cystatin C with GFR estimated by serum creatinine in a sample of 50 pediatric renal transplant recipients and 24 healthy children. The correlation between GFR estimated by serum creatinine and by cystatin C was significant (r = 0.75; P < 0.001, Person’s correlation); however, in pediatric kidney transplant recipients, the GFR was 6.7 mL/min lower when determined using cystatin C rather than serum creatinine. Moreover, using GFR estimated by cystatin C we found that 42 percent of the pediatric kidney transplant recipients had an estimated GFR <60 mL·min-1·1.73 (m²)-1, whereas when GFR was estimated by the serum creatinine formula only 16 percent of the children had values below this cutoff point indicative of chronic kidney disease (P < 0.001). We conclude that, in pediatric kidney transplant recipients, estimation of GFR yields lower values when cystatin C is used rather than serum creatinine.

Exploratory calcineurin inhibitor-free regimens in living-related kidney transplant recipients

Chronic allograft nephropathy is among the major causes of graft loss even in low-risk kidney transplant recipients and correlates with acute nephrotoxic events during the first year post-transplant. Therefore, calcineurin inhibitor-free regimens may improve patient and graft survival among recipients of living-related kidney transplants. To confirm this hypothesis, we evaluated the efficacy and safety of two calcineurin inhibitor-free regimens in 92 low-risk recipients of one-haplotype living-related kidney transplants. Immunosuppression consisted of tacrolimus, azathioprine and prednisone (group I, GI, N = 38), 2 doses of daclizumab, mycophenolate mofetil (MMF), and prednisone (GII, N = 33) and 2 doses of daclizumab, MMF, sirolimus and prednisone (GIII, N = 21). At 12 months, treatment failure (biopsy-confirmed acute rejection, graft loss or death) was higher in GII compared to GIII and GI (54.5 vs 24.0 vs 13.1 percent, P < 0.01, respectively). In patients of black ethnicity the incidence of acute rejection was 25 vs 83.3 vs 20 percent (P = 0.055), respectively. Patient and graft survival was comparable. There were no differences in mean creatinine or calculated creatinine clearance at 12 months. Overall incidence of post-transplant diabetes mellitus (3.3 percent) and cytomegalovirus disease (4.3 percent) was similar in all groups. Further development of effective calcineurin inhibitor-free regimens should exclude patients of black ethnicity and may need full-induction therapy, perhaps with depleting agents, and concentration-controlled use of sirolimus and MMF.

Impact of initial exposure to calcineurin inhibitors on kidney graft function of patients at high risk to develop delayed graft function

We conducted a retrospective analysis of the influence of full doses of calcineurin inhibitors [8-10 mg kg-1 day-1 cyclosporine (N = 80), or 0.2-0.3 mg kg-1 day-1 tacrolimus (N = 68)] administered from day 1 after transplantation on the transplant outcomes of a high-risk population. Induction therapy was used in 13 percent of the patients. Patients also received azathioprine (2 mg kg-1 day-1, N = 58) or mycophenolate mofetil (2 g/day, N = 90), and prednisone (0.5 mg kg-1 day-1, N = 148). Mean time on dialysis was 79 ± 41 months, 12 percent of the cases were re-transplants, and 21 percent had panel reactive antibodies >10 percent. In 43 percent of donors the cause of death was cerebrovascular disease and 27 percent showed creatinine above 1.5 mg/dL. The incidence of slow graft function (SGF) and delayed graft function (DGF) was 15 and 60 percent, respectively. Mean time to last dialysis and to nadir creatinine were 18 ± 15 and 34 ± 20 days, respectively. Mean creatinine at 1 year after transplantation was 1.48 ± 0.50 mg/dL (DGF 1.68 ± 0.65 vs SGF 1.67 ± 0.66 vs immediate graft function (IGF) 1.41 ± 0.40 mg/dL, P = 0.089). The incidence of biopsy-confirmed acute rejection was 22 percent (DGF 31 percent, SGF 10 percent, IGF 8 percent). One-year patient and graft survival was 92.6 and 78.4 percent, respectively. The incidence of cytomegalovirus disease, post-transplant diabetes mellitus and malignancies was 28, 8.1, and 0 percent, respectively. Compared to previous studies, the use of initial full doses of calcineurin inhibitors without antibody induction in patients with SGF or DGF had no negative impact on patient and graft survival.

Relationship of cyclosporin and sirolimus blood concentrations regarding the incidence and severity of hyperlipidemia after kidney transplantation

The influence of drug concentrations on the development of persistent posttransplant hyperlipidemia was investigated in 82 patients who received cyclosporin A (CsA) and prednisone plus sirolimus (SRL) (52) or azathioprine (AZA) (30) during the first year after transplantation. Blood levels of CsA and SRL, daily doses of AZA and prednisone, and cholesterol, triglyceride, and glucose concentrations were determined during each visit (pretransplant and 30, 60, 90, 120, 180, and 360 days posttransplant). Persistent hyperlipidemia was defined as one-year average steady-state cholesterol (CavCHOL) or triglyceride (CavTG) concentrations above 240 and 200 mg/dL, respectively. Mean cholesterol and triglyceride concentrations increased after transplantation (P < 0.01) and were higher in patients receiving SRL compared to AZA (P < 0.001). Patients receiving SRL showed a significantly higher number of cholesterol (>229 or >274 mg/dL) and triglyceride (>198 or >282 mg/dL) determinations in the upper interquartile ranges. CsA and SRL interquartile ranges correlated with cholesterol concentrations (P = 0.001) whereas only SRL interquartile ranges correlated with triglyceride concentrations (P < 0.0001). Only pretransplant cholesterol concentration >205 mg/dL was independently associated with development of persistent hypercholesterolemia (CavCHOL >240 mg/dL, relative risk (RR) = 20, CI 3.8-104.6, P = 0.0004) whereas pretransplant triglyceride concentration >150 mg/dL (RR = 7.2, CI 1.6-32.4, P = 0.01) or >211 mg/dL (RR = 19.8, CI 3.6-107.9, P = 0.0006) and use of SRL (RR = 3, CI 1.0-8.8, P = 0.0049) were independently associated with development of persistent hypertriglyceridemia (CavTG >200 mg/dL). Persistent hypercholesterolemia was more frequent among patients with higher pretransplant cholesterol concentrations and was dependent on both CsA and SRL concentrations. Persistent hypertriglyceridemia was more frequent among patients with higher pretransplant triglyceride concentrations and was dependent on SRL concentrations.

Pharmacokinetic/pharmacodynamic relationships of FTY720 in kidney transplant recipients

FTY720 is a new and effective immunosuppressive agent, which produces peripheral blood lymphopenia through a lymphocyte homing effect. We investigated the relationship between the dose of FTY720 or blood concentration (pharmacokinetics, PK) and peripheral lymphopenia (pharmacodynamics, PD) in 23 kidney transplant recipients randomized to receive FTY720 (0.25-2.5 mg/day) or mofetil mycophenolate (2 mg/day) in combination with cyclosporine and steroids. FTY720 dose, blood concentrations and lymphocyte counts were determined weekly before and 4 to 12 weeks after transplantation. The effect of PD was calculated as the absolute lymphocyte count or its reductions. PK/PD modeling was used to find the best-fit model. Mean FTY720 concentrations were 0.36 ± 0.05 (0.25 mg), 0.73 ± 0.12 (0.5 mg), 3.26 ± 0.51 (1 mg), and 7.15 ± 1.41 ng/ml (2.5 mg) between 4 and 12 weeks after transplantation. FTY720 PK was linear with dose (r² = 0.98) and showed low inter- and intra-individual variability. FTY720 produced a dose-dependent increase in mean percent reduction of peripheral lymphocyte counts (38 vs 42 vs 56 vs 77, P < 0.01, respectively). The simple Emax model [E = (Emax * C)/(C + EC50)] was the best-fit PK/PD modeling for FTY720 dose (Emax = 87.8 ± 5.3 percent and ED50 = 0.48 ± 0.08 mg, r² = 0.94) or concentration (Emax = 78.3 ± 2.9 percent and EC50 = 0.59 ± 0.09 ng/ml, r² = 0.89) vs effect ( percent reduction in peripheral lymphocytes). FTY720 PK/PD is dose dependent and follows an Emax model (EC50 = 0.5 mg or 0.6 ng/ml). Using lymphopenia as an FTY720 PD surrogate marker, high percent reductions ( about 80 percent) in peripheral lymphocytes are required to achieve best efficacy to prevent acute allograft rejection.

Preservation of graft function in low-risk living kidney transplant recipients treated with a combination of sirolimus and cyclosporine

The use of sirolimus (SRL) in combination with full doses of cyclosporin A (CsA) results in reduced one-year kidney allograft function, which is associated with shorter long-term allograft survival. We determined the effect of reduced CsA exposure on graft function in patients receiving SRL and prednisone. Ninety recipients of living kidney transplants receiving SRL (2 mg/day, po) were compared to 35 recipients receiving azathioprine (AZA, 2 mg kg-1 day-1, po). All patients also received CsA (8-10 mg kg-1 day-1, po) and prednisone (0.5 mg kg-1 day-1). Efficacy end-point was a composite of biopsy-confirmed acute rejection, graft loss, or death at one year. Graft function was measured by creatinine, creatinine clearance, and graft function deterioration between 3 and 12 months (delta1/Cr). CsA concentrations in patients receiving SRL were 26 percent lower. No differences in one-year composite efficacy end-point were observed comparing SRL and AZA groups (18 vs 20 percent) or in the incidence of biopsy-proven acute rejection (14.4 and 14.3 percent). There were no differences in mean ± SD creatinine (1.65 ± 0.46 vs 1.60 ± 0.43 mg/dl, P = 0.48) or calculated creatinine clearances (61 ± 15 vs 62 ± 13 ml/min, P = 0.58) at one year. Mean ± SD delta1/Cr (-11 ± 17 vs -14 ± 15 percent, P = 0.7) or the percentage of patients with >20 percent (26 vs 31 percent, P = 0.6) or >30 percent delta1/Cr (19 vs 17 percent, P = 1) did not differ between the two groups. The use of 2-mg fixed oral doses of SRL and reduced CsA exposure was effective in preventing acute rejection and preserving allograft function.

The role of CD8+ T cells during allograft rejection

Organ transplantation can be considered as replacement therapy for patients with end-stage organ failure. The percent of one-year allograft survival has increased due, among other factors, to a better understanding of the rejection process and new immunosuppressive drugs. Immunosuppressive therapy used in transplantation prevents activation and proliferation of alloreactive T lymphocytes, although not fully preventing chronic rejection. Recognition by recipient T cells of alloantigens expressed by donor tissues initiates immune destruction of allogeneic transplants. However, there is controversy concerning the relative contribution of CD4+ and CD8+ T cells to allograft rejection. Some animal models indicate that there is an absolute requirement for CD4+ T cells in allogeneic rejection, whereas in others CD4-depleted mice reject certain types of allografts. Moreover, there is evidence that CD8+ T cells are more resistant to immunotherapy and tolerance induction protocols. An intense focal infiltration of mainly CD8+CTLA4+ T lymphocytes during kidney rejection has been described in patients. This suggests that CD8+ T cells could escape from immunosuppression and participate in the rejection process. Our group is primarily interested in the immune mechanisms involved in allograft rejection. Thus, we believe that a better understanding of the role of CD8+ T cells in allograft rejection could indicate new targets for immunotherapy in transplantation. Therefore, the objective of the present review was to focus on the role of the CD8+ T cell population in the rejection of allogeneic tissue

Neoplasia em transplante de órgäos / Tumors in organ transplantation

Desde a década de 1960, sabe-se que a terapia imunossupressora está associada a maior incidência de neoplasias. Esse conhecimento é válido para qualquer tipo de transplante, principalmente quando säo empregados esquemas com várias drogas, mas sua real incidência ainda näo é perfeitamente conhecida. As neoplasias mais prevalentes nos pacientes submetidos a transplante säo as cutâneas, as que acometem o trato geniturinário, as do trato digestivo e os linfomas. O tratamento dessas neoplasias varia des a simples diminuiçäo até a suspensäo do esquema de imunossuspressäo, às vezes com necessidade de exéreses cirúrgicas, com ou sem quimioterapia e/ou radioterapia.

Sobrevida de pacientes diabéticos em diálise / Survival of diabetic patients in dialysis

OBJETIVO. Diabetes melito é uma causa de insuficiência renal terminal de importância crescente. Nosso objetivo foi avaliar a sobrevida depacientes diabéticos e näo-diabéticos em tratamento dialítico. MATERIAL E MÉTODOS. Foram estudados 295 pacientes em programa de diálise em um centro de referência terciário na cidade de Säo Paulo, entre 1992 e 1994. Setenta e um paciente eram diabéticos (17 do tipo I e 54 do tipo II) e 224 tinham outros diagnósticos dedoença de base. Os dados foram coletados prospectivamente através de formuláriospadronizados, e também retrospectivamente, para pacientes que iniciaram tratamento entre 1992 e junho 1993. Análise de sobrevida foi realizada por meio do método do produto limite. RESULTADOS. Os pacientes diabéticos apresentavam média de idade mais elevada e uma maior proporçäo utilizava diálise peritoneal em relaçäo aos näo-diabéticos. Após um ano, a taxa de sobrevida foi 67 por cento e 86 por cento para pacientes diabéticos e näo-diabéticos (p<0,0001). A diferença de sobrevida se acentuou com a duraçäo do tratamento. Esta diferença foi observada tantoem pacientes mais jovens (ó50 anos) quanto nos mais idosos, embora tenha sido mais precoce nos primeiros. A sobrevida dos diabéticos permaneceu significantemente reduzida, ajustando-se para a idade dos pacientes. CONCLUSÖES. Pacientes diabéticos em diálise apresentam taxa de sobrevida inferior aos näo-diabéticos, independentemente da sua idade média mais elevada. Cuidados especiais devem ser dedicados a estes pacientes, tanto em relaçäo a fatores co-mórbidos pré-diálise quanto durante o tratamento dialítico, a fim de se melhorar a sua sobrevida.

Farmacocinética da ciclosporina e de seus metabólicos em pacientes submetidos a transplante renal / Pharmacokinetics of cyclosporine and its metabolites in patients undergoing kidney transplantation

A farmacocinética da ciclosporina demosntra grande variaçäo inter e intra-individual e profundas mudanças säo, freqüentemente, observadas após o transplante renal. OBJETIVO. analisar seriadamente a farmacocinética da ciclosporina e de seus metabólitos através da determinaçäo de sua concentraçäo sanguínea, em pacientes submetidos a transplante renal. MÉTODOS. Foram realizados 70 estudos em 29 pacientes, sendo 26 antes e 44 após o transplante renal. Em cada estudo a curva de absorçäo foi analisada mediante a determinaçäo da concentraçäo sanguínea da ciclosporina, utilizando radioimunoensaio com anticorpos monoclonais específicos (RIE-MoSP) e inespecíficos (RIE-MoNP), em 17 amostras colhidas após a sua administraçäo oral ou endovenosa (0; 0,5; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 12; 16; 20; 23; 24h). Resultados. A área sob a curva da concentraçäo sanguínea de ciclosporina em funçäo do tempo (AUC), a biodisponibilidade (F), a concentraçäo máxima (Cmax) e as concentraçöes sanguíneas obtidas 12 e 24 horas após a sua administraçäo (C12 e C24), determinadas com RIE-MoSP, foram inferiores àquelas encontradas com RIE-MoNP, enquanto a depuraçäo (CL) e o volume de distribuiçäo (Vd) foram maiores. A meia-vida de eliminaçäo foi semelhante utilizando os dois métodos (t1/2). A absorçäo seguiu uma cinética de ordem zero, sendo observada uma correlaçäo inversa entre a dose de ciclosporina e a AUC/dose (r = 0,55, RIE-MoSP e r = 0,42, RIE-MoNP). A fraçäo de absorçäo (F) variou entre 18 por cento e 68 por cento (RIE-MoSP), sendo superestimada quando determinada com RIE-MoNP (38 por cento a 100 por cento), conseqüência da extensa metabolizaçäo na primeira passagem pelo intestino e fígado...

Meningiomas en el Hospital Universitario de Caracas en los últimos 20 años / Meningiomas in the Hospital Universitario of Caracas in the last twenty years

El presente trabajo constituye una revisión de 135 casos que son la totalidad de los meningiomas comprobados anatomopatológicamente desde 1964 hasta el primer semestre de 1984, en el Servicio de Neurocirugía del Hospital Universitario de Caracas. La distribución por edad estuvo entre la 2da. década, 5 casos; 3ra. década, 10 casos; 4ta. década, 18 casos; 5ta. década, 30 casos 6ta década, 31 casos; 7a. década, 5 casos en los femeninos y 2,3,7,7,12 y 5 casos respectivamente en los masculinos. La sintomatología clínical global se ordenó por frecuencia en cefaleas, 58,51% trastornos visuales, 31,11%; trastornos motores, 22,22%; vómitos, 18,51%; trastornos sensoriales, 14,81%; convulsiones, 14,07%; diplopia, 11,11% y otros, 17,03%. Los signos se jerarquizan así: trastornos motores, 48,14% edema de papila, 47,40%; alteraciones de reflejos, 39,25%; toque de pared craneales, 37,77%; otros, 5,18%. Los tipos histológicos fueron: Meningotelial, 52,52% femeninos; 50% masculinos. Mixto-transicional, 22,23% y 36,11% Hemangiopericítico, 3,02% femenino y 5,5% masculino. Sarcomatoso, 2,02%; fibrosblásticos, 20% femenino y 8,30%, masculino. Todos fueron intervenidos. La evolución post-operatoria fué buena,89 casos sin radioteralia y 9 casos con radioterapia; fué regular en 23 casos sin radioterapia y 2 casos con radioterapia. Hubo 12 casos mortales. El seguimiento varió de 5 meses a 11 años. Hubo un total de recidivas de 32,32% femeninos y 33,33 masculinos

A importancia da determinacao do valor da hemoglobina no calculo do excesso de base (BE) em um hospital de grande porte. / Importance of the determination of hemoglobin levels for the calculation of base excess parameters in a general hospital

No presente trabalho, os autores chamam a atencao para a importancia do calculo de cada Excesso de Base (BE) baseado no valor da respectiva concentracao de hemoglobina (Hb), ja que encontraram 87% de niveis de hemoglobina abaixo de 15,0 g/dl em sua casuistica. Foi estudada uma centena de casos e foram comapardos os valores em 2 grupos: I) o valor real da hemoglobina do pacientes e II) considerando a hemoglobina como 15,0 g/dl. Foi usado o teste de McNemar para tal comparacao e se observou uma discordancia significativa (X2 = 17,47).Outro nivel de igualdade foi medido por um teste t pareado para a concentracao da Hb em 2 series de amostras sanguineas dos mesmos pacientes, para comparar EDTA e heparina como anticoagulantes. Nao se encontrou nenhuma diferenca significativa. O uso de heparina somente como anticoagulante tornou a colheita mais simples, por ser usada para ambos os testes (Hb e BE)