Luis Salinas-Madrigal

Percutaneous renal biopsy in the 1990s: Safety, value, and implications for early hospital discharge

To determine the parameters associated with significant bleeding and to examine the value of performing a renal biopsy, we studied 83 consecutive patients, including 24 renal allograft recipients, who had undergone percutaneous renal biopsy. The patients were stratified into four groups according to the percentage of decline in their hematocrit (Hct) at 24 hours postbiopsy, as follows: 10% or greater (n = 21; 25%) and less than 10% decline (n = 62; 75%). The latter group was further subgrouped into 5% to 10% (n = 22) and less than 5% decline (n = 40). There was a significant decline in Hct postbiopsy, with a linear correlation between the decrease in Hct at 6 and 24 hours (R2 = 0.47; P < 0.0001), suggesting that the former was a predictor of the latter. There was a linear correlation between the number of passes and number of cores obtained for the first four passes, but an inverse correlation when five passes or greater were required. Interestingly, there was no correlation between bleeding (>10% decline in Hct) and the number of passes or cores obtained. Gross hematuria and blood transfusion requirement were each encountered in three patients (3.6%). Importantly, the prebiopsy clinical diagnosis was altered in 18 of 59 native kidney biopsies (33%) and 10 of 24 transplant biopsies (41%). We conclude that percutaneous renal biopsy using an automated spring-loaded gun device coupled with ultrasound guidance is a safe technique and provides essential clinical information. Importantly, patients with a stable Hct at 6 hours were at low risk for bleeding at 24 hours while hospitalized. It remains to be determined if these findings could be extrapolated to early discharge from hospital.

C4d peritubular capillary staining in chronic allograft nephropathy and transplant glomerulopathy: an uncommon finding

The true incidence of positive C4d staining in the peritubular capillaries of biopsies with chronic allograft nephropathy (CAN) and transplant glomerulopathy (TGP) remains controversial. We retrospectively reviewed all transplant biopsies performed at Saint Louis University Hospital between June 2002 and May 2004. We examined the incidence of positive C4d staining in the peritubular capillaries of biopsy specimens with pure CAN with or without features of TGP. We identified 54 biopsies in 43 patients showing CAN. The average age was 46 ± 13 years. The average creatinine at the time of biopsy was 308 ± 211 μmol/l (3.5 ± 2.4 mg/dl). Twenty (37%) biopsies exhibited features consistent with TGP. Only two biopsies had positive C4d staining in the peritubular capillaries. The C4d positive biopsies were from two different patients; one patient had donor specific antibodies (DSA) against HLA class 1 at the time of biopsy and the other patient had no detectable DSA. None of the TGP biopsies showed peritubular C4d staining. C4d staining of the peritubular capillaries appears to be rare in patients with pure CAN with and without TGP features.

Experimental Ureteral Obstruction in the Fetal Opossum: Histologic Assessment

In the North American opossum, Didelphis virginiana unilateral complete ureteral obstruction (ECO) and partial unilateral (EPO) ureteral obstruction were created during the early metanephric stage of kidney development in pups attached to the teat (approximately 4.5 cm. long, 20 days old). At 70 days of pouch life (full-term equivalent in the human) some completely obstructed ureters were unobstructed with reanastomosis in the bladder (RECO). Other pups underwent unilateral complete ureteral ligation at this full-term equivalent (70 days of pouch life) and constituted the late obstruction (LCO) group. Unoperated animals constituted the control (C) group. All animals were harvested when full grown (.7 to 2.2 kg.), and paraffin sections of the kidneys were stained with hematoxylin and eosin and Massons Trichrome. In each a semiquantitative assessment of 24 histologic features was made and a digital score assigned. All experimental groups except EPO demonstrated significant epithelial and mesenchymal alterations. The changes can be broadly categorized as those secondary to obstruction of urine flow (dilation and cystic changes), those affecting epithelial differentiation in both cortex and medulla and those affecting mesenchymal differentiation. The EPO group demonstrated significantly fewer glomerular generations than did control kidneys. For all other characteristics studied, the EPO group did not differ from control. The ECO group demonstrated significant changes when compared with control for most parameters studied. Medullary dysplasia was more prominent in kidneys obstructed early. Reanastomosis (RECO) at a full-term equivalent did ameliorate the changes of medullary dysplasia and cortical atrophy. More collecting duct hyperplasia, cortical and medullary aplasia were present in the LCO group compared with the ECO. The LCO group also had less primitive duct formation and less medullary dysplasia than the ECO group. Renal blastema, previously unreported in experimental obstruction, was present in 41% of experimental kidneys.

Induced renal dysplasia in the young pouch opossum

Using the North American opossum, Didelphis virginiana, we have developed a new model for studying the effects of early fetal urinary obstruction on subsequent renal development. We have successfully induced renal dysplasia in the marsupial that has a typically mammalian kidney.

Renoprotective effects of the 21-aminosteroid U74389G in ischemia-reperfusion injury and cold storage preservation

Free radical mediated lipid peroxidation (LPO) has been implicated in the pathogenesis of ischemic-reperfusion injury (IRI). To address the renoprotective effect(s) of LPO inhibition, the efficacy of the 21 aminosteroid U74389G was evaluated in three IRI models. In Model 1 51 unilateral nephrectomized rats that underwent 60 min of warm ischemia followed by a 72-hr reperfusion interval were treated with the test vehicle only, or 3, 6, or 12 mg/kg of U74389G intravenously, 5 min pre- or postischemia. In Model 2 Sprague-Dawley rats underwent sham operation (n=9), or 45 min of warm ischemia and 10 min of reperfusion with U74389G (6 mg/kg; n=10) or test vehicle only (n=10) administered intravenously over 10 min beginning 5 min prior to clamp release. After reperfusion, LPO was determined by assay of snap frozen tissue for thiobarbituric acid (TBA) concentrations (nmol/g tissue weight). In Model 3 domestic lean maid pigs (14-18 kg) underwent left nephrectomy with 30 min of warm ischemia, Collins C-4 flush, and 24 hr of cold storage preservation. Heterotopic autotransplantation and immediate contralateral nephrectomy was then performed in Group A-nonischemic controls (n=4), Group B-ischemic controls (n=5), and Group C-U74389G (6 mg/kg) administered preischemia and at autotransplantation (n=5). In Model 1 maximal renoprotection was demonstrated with the 6 mg/kg dose of U74389G administered after ischemia (ischemic control 72-hr serum creatinine (Cr) = 8.01+/-1.1 mg% vs. 3.32+/-0.96 mg%; ischemic control creatinine clearance = 0.069+/-0.03 ml/min vs. 0.206+/-0.04 ml/min; P<0.05). In Model 2 TBA levels were significantly lower in U74389G treated animals (88.5+/-10.0 vs. ischemic controls = 296.8+/-81.4; P=0.02). In Model 3 graft survivals were 100%, 0%, and 60% respectively. Peak Cr and BUN (mg%) were significantly greater in Group C vs. Group A, (Group A Cr = 8.59+/-0.63 vs. Group C = 12.8+/-1.01; Group A BUN = 64.1+/-2.73 vs. Group C = 104.9+/-12.21)--however, by day 10, thee were no significant differences in renal function: (Group A Cr = 2.15+/-0.3 vs. Group C = 2.10+/-0.06; Group A BUN = 27.0+/-6.0 vs. Group C = 31.1+/-6.4). These results support the beneficial effects of LPO inhibitors in models of ischemia-reperfusion, as well as preservation/transplantation, and suggest that this renoprotection correlates with decreased membrane lipid peroxidation.

Renal allograft biopsies in the era of C4d staining: the need for change in the Banff classification system

C4d immunostaining in the peritubular capillaries (PTC) is a marker of antibody‐mediated rejection (AMR). We evaluated the histopathologic diagnoses of 388 renal transplant biopsies since the implementation of routine C4d immunostaining at our center. Of these, 155 (40%) biopsies had evidence of acute cellular rejection (ACR), out of which 119 (77%) had pure ACR, 31 (20%) had ACR with concomitant features of AMR, and five (3%) had ACR with focal C4d staining. Sixty‐four (16%) biopsies exhibited features of AMR [33 (52%) pure AMR, and 31(48%) concomitant AMR and ACR]. One hundred and fifty‐five (40%) biopsies had features of interstitial fibrosis and tubular atrophy (IFTA). Of these, 20 (13%) had concomitant AMR [13 (8.5%) had pure AMR and seven (4.5%) had concomitant ACR and AMR]. Creatinine at the time of biopsy was higher in patients with mixed ACR and AMR and the clinical behavior of mixed lesions is more aggressive over time. Despite having a lower serum creatinine at the time of biopsy, patients with IFTA experienced gradual decline in graft function over time. The pathologic findings in renal allograft biopsies are often mixed and mixed lesions appear to have more aggressive clinical behavior. These findings suggest the need for change in the Banff classification system to better capture the complexity of renal allograft pathologies.

Experimental ureteral obstruction in the fetal opossum. I, Renal functional assessment

The North American opossum Didelphis virginiana was used as a model for fetal urinary obstruction. In this animal the fetus develops on a teat in a pouch and, therefore, it is accessible to surgical intervention. Unilateral ureteral obstruction was created at a mid trimester developmental equivalent in 8 pups, late ureteral obstruction was created in a similar fashion in 6 pups at a full-term equivalent and unobstruction of 9 pups was accomplished with a ureteroneocystostomy at a full-term equivalent. After early intervention 6 pups were found to have only partial ureteral obstruction as measured by mild dilatation and probe patency of the ureter. The control group consisted of 11 unoperated animals. The animals were maintained until adulthood when they were harvested after obtaining creatinine clearances from both kidneys. All dilated urinary systems were cultured for bacteria and they were sterile.

Acute Thrombosis of the Renal Transplant Artery after a Single Dose of OKT3

We present the case of an 18-year-old male who 8 months after a living-related donor, one-haplotype-matched renal transplantation developed acute thrombosis of the renal allograft artery, within 10 h of the first dose of OKT3. The antibody therapy had followed five daily doses of intravenous pulse methylprednisolone for a Banff class 1B acute tubulointerstitial rejection, on a ciclosporin-based immunosuppression protocol. We briefly review the literature on the incidence of vascular thrombosis after transplantation and the procoagulant effects of OKT3, pulse methylprednisolone, and ciclosporin therapy.

Evaluation of the thromboxane A2 synthetase inhibitor OKY-046 in a warm ischemia-reperfusion rat model.

The pathophysiology of ischemia-reperfusion renal injury is mediated, in part, by the generation of the vasoconstricting prostanoid thromboxane A2 (TXA2). This study was undertaken to evaluate the renoprotective effects, as well as the optimal timing and dosage, of a selective thromboxane synthetase inhibitor, OKY-046, in a unilateral nephrectomized, 60 min ischemia, 72 hr reperfusion, rodent model. Forty-one rats were subjected to right nephrectomy only (group A), or right nephrectomy with 60 min of left renal ischemia and treatment with inactive vehicle only (group B), or 2 mg/kg or 4 mg/kg of OKY-046 administered intravenously before (groups C and D) or after (groups E and F) pedicle clamping. Outcome variables included animal survival; change in kidney weight; 0, 24, and 72 hr plasma creatinine (CR); urea nitrogen (BUN); thromboxane B2 (TXB2) and 6-keto prostaglandin F(1alpha) (6 kPGF(2alpha)) levels; creatinine clearance (CRCL); and histologic evidence of renal injury. Animal survival and postperfusion kidney weight were not significantly different among the groups. However, renal functional parameters were significantly improved with the 2 mg/kg dose of OKY-046 administered after renal ischemia. (group B 72 hr Cr= 8.01 +/- 1.1 mg% vs. group E=3.99 +/- 1.5 mg%, and group B 72 hr BUN=241.3 +/- 32.8 mg% vs. group E=52.6 +/- 22.5 mg%). The CRCL was also improved in group E vs. group B, although these results did not reach statistical significance (group B=0.069 ml/min vs. group E=0.194 ml/ min). The 24 hr TXB2 levels were significantly increased in group B (0 hr=754.1 +/- 219.4 pg/ml vs. 24 hr=2055.9 +/- 550.0 pg/ml), and pre- or posttreatment with OKY-046 abrogated this increase (group C 0 hr=517.1 +/- 80.9 pg/ml vs. 24 hr=384.7 +/- 251.5 pg/ml, and group E 0 hr=781.6 +/- 390.4 pg/ml vs. 24 hr=183.0 +/- 81.4 pg/ml). The 24 hr 6 kPGF(1alpha) levels decreased in all groups, whereas 72 hr 6 kPGF(1alpha) levels increased above baseline in groups A, C, and E, but not in group B. These data demonstrate the beneficial effects of thromboxane A2 synthesis inhibition in the setting of ischemia-reperfusion injury and suggest that this renoprotection correlates with late vasodilatory prostanoid synthesis.

Morphologic Diagnosis of Acute Tubular Necrosis (ATN) by Autofluorescence

The histologic diagnosis of acute tubular necrosis (ATN) frequently poses considerable difficulty, especially in its early phases. This is particularly true in postmortem material in which autolysis is commonly present. This study was designed to assess the value of enhanced autofluorescence in the diagnosis of ATN. The method has previously been shown to be useful in the identification of myocardial infarcts in both humans and experimental animals. We studied 12 patients with a histologic and clinical diagnosis of ATN. In all, severe hypotension of diverse etiology was detected from 15 hours to seven days prior to death. In all cases, a bright yellow autofluorescence was observed in the necrotic tubules in ordinary H & E sections. In addition, enhanced autofluorescence was observed in the necrotic tubular epithelium in the unstained, paraffin-embedded sections. Nine kidney sections from five medico-legal autopsy cases undergoing autolysis from 11 to 48 hours after death were used as controls. These kidneys invariably exhibited a faint dull olive green fluorescence, quite different from the fluorescence of the necrotic tubules. No effort was made to distinguish between ischemic (tubulorrhexis) and toxic (tubulonecrosis) changes by the fluorescent method. The mechanism of the enhanced autofluorescence is not clear. We conclude that ultraviolet light examination of H & E kidney sections allows accurate recognition of ATN.