Gustavo Garcia Parra - Academia.edu (original) (raw)

Papers by Gustavo Garcia Parra

Research paper thumbnail of Melatonin attenuates acute renal failure and oxidative stress induced by mercuric chloride in rats

American Journal of Physiology-Renal Physiology, 2000

We evaluated the effect of melatonin (Mel), a potent scavenger of reactive oxygen species, in the... more We evaluated the effect of melatonin (Mel), a potent scavenger of reactive oxygen species, in the course of HgCl2-induced acute renal failure. Rats received by gastric gavage 1 mg/kg of Mel ( n = 21) or vehicle ( n = 21), 30 min before the subcutaneous injection of HgCl2(2.5 mg/kg). Rats were killed at 24, 48, and 72 h, and plasma creatinine (Scr), renal histology, proliferative activity, apoptosis, and superoxide-producing cells were studied. We also determined the renal content of malondialdehyde (MDA) and glutathione (GSH) and the activities of glutathione peroxidase and catalase. Mel pretreatment (Mel plasma levels of 3.40 ± 3.15 μg/ml at the time of HgCl2injection) prevented the increment in Scrand reduced tubular necrosis from 41.0 ± 10.5 to 4.2 ± 5.1% of proximal tubules ( P < 0.01). Apoptosis and postnecrotic proliferative activity were twice more intense in the group untreated with Mel. Increment in renal content of MDA and decrease in GSH resulting from HgCl2toxicity we...

Research paper thumbnail of Effect of uric acid on nephrotoxicity induced by mercuric chloride in rats

Toxicology and Industrial Health, 2010

Oxidative stress is an important mechanism in mercury poisoning. We studied the effect of uric ac... more Oxidative stress is an important mechanism in mercury poisoning. We studied the effect of uric acid, a natural and potent reactive oxygen species and peroxynitrite scavenger, in HgCl 2-induced nephrotoxicity. Rats were injected with a unique dose of HgCl2 (2.5 mg/kg body weight, subcutaneously) and then vehicle (for 3 days, twice daily) or HgCl2 (unique dose) and intraperitoneal uric acid suspension (250 mg/kg body weight, twice daily, for 3 days), and then killed at 24, 48 and 72 hours after HgCl2 administration (n = 5 for each group). At the end of the experimental study, kidneys and blood samples were taken. Tissues were prepared and examined under light microscopy. Uric acid significantly prevented the increase in plasma levels of creatinine and blood urea nitrogen (BUN); it helped maintain systemic nitrate/nitrite concentration and total antioxidant capacity. Uric acid attenuated the increase of renal lipid peroxidation and it markedly diminished nitrotyrosine signal and histop...

Research paper thumbnail of Cell populations and membrane attack complex in glomeruli of patients with post-streptococcal glomerulonephritis: Identification using monoclonal antibodies by indirect immunofluorescence

Clinical Immunology and Immunopathology, 1984

Poststreptococcal glomerulonephritis (PSGN) had been thought to arise from renal deposition of im... more Poststreptococcal glomerulonephritis (PSGN) had been thought to arise from renal deposition of immune complexes and as such is analogous to acute serum sickness. Recent studies of acute serum sickness in animals and PSGN in humans, however, have suggested a pathogenetic role for cellular immunity. To enlarge on these observation?. cellular components of glomeruli were characterized by indirect immunofluorescence in Ii tissues from individuals with PSGN using monoclonal antibodies. These studies demonstrate infiltration of glomeruli by monocytes, granulocytes. and lymphoid cells. Focal accumulations of T lymphocytes were also observed adjacent to Bowman's capsule. Analysis of glomerular T-cell subpopulations revealed a predominance of cells reactive with OKT4 early and with OKT8 later in the course of disease. Proliferation of parietal and visceral epithelial cells was associated with increased binding of BA-I and J.5, respectively. The presence of the membrane attack complex of complement was demonstrated by glomerular reactivity with a monoclonal antibody (poly-CY MA) which recognizes a neoantigen present in poly-C9. Fluorescence was present along the glomerular basement membrane early and within the mesangium late in the course of disease. a distribution similar to that observed for C3 and C5. These observations suggest that immune cells as well as terminal components of complement either provoke or mark tissue injury in PSGN. Cl 1984 Academtc Prec\. Ini-' Under the tenure of a Fundaciti Grant.

Research paper thumbnail of Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric oxide inhibition

Kidney International, 2003

Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric... more Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric oxide inhibition. Background. Angiotensin II (Ang II) infusion and nitric oxide synthesis (NOS) inhibition with N-nitro-l-arginine-methylester (l-NAME) are experimental models of hypertension associated with renal inflammation and oxidative stress. To gain insight into the nature of the tubulointerstitial injury induced in these models, we studied lectin-binding specificities, vimentin expression, and heat shock protein (HSP) 60 and 70 in these experimental models. Methods. Sprague-Dawley rats received Ang II infusion (435 ng/kg/min) for 2 weeks by subcutaneous minipumps (Ang II group, N ϭ 5) or l-NAME in the drinking water (70 mg/ 100 mL) for 3 weeks (l-NAME group N ϭ 7). The control group consisted of 10 rats. Systolic blood pressure (tail-cuff plethysmography), serum creatinine, and proteinuria were determined weekly. At the end of the treatment period, rats were sacrificed and kidneys studied. Binding specificities of fluorescein-labeled lectins were examined in frozen sections, and cellular infiltrates were identified by immunohistology and expression of vimentin and HSP 60 and 70 with immunohistochemistry and computer image analysis. Results. Tubulointerstitial accumulation of macrophages, lymphocytes, and Ang II-positive cells were present in the Ang II group and l-NAME group. Vimentin, HSP 60, and HSP 70 were increased 8 to 20 times in the cortex of the rats of the Ang II group and the l-NAME groups. Neoexpression of vimentin and HSPs was found primarily in proximal tubular cells. Conclusion. Ang II infusion and NOS inhibition induce tubular injury with epithelial cell transdifferentiation and expression of stress proteins. The role of these changes in the accumulation and activation of the interstitial inflammatory infiltrate merits further investigation.

Research paper thumbnail of Experimental induction of salt-sensitive hypertension is associated with lymphocyte proliferative response to HSP70

Kidney International, 2008

Renal tubulointerstitial inflammation is a constant feature of experimental models of hypertensio... more Renal tubulointerstitial inflammation is a constant feature of experimental models of hypertension and likely plays a role in the pathogenesis of salt-sensitive hypertension. We have previously raised the possibility that the immune cell infiltration is driven by a low grade autoimmune reactivity directed to or facilitated by renal heat shock protein over expression. The present studies were done to gain insight on possible cell-mediated immune mechanisms in experimental hypertension by determining the renal expression of HSP70 and the proliferation index of T lymphocytes cultured with HSP70. We studied male Sprague-Dawley rats with inhibition of nitric oxide (NO) synthase (n ¼ 6), protein overload (PO) proteinuria (n ¼ 7) and short-term angiotensin II (Ang II) infusion (n ¼ 5), and their corresponding control groups. Each model was associated with 2 to 4 fold increase (Po0.05-0.001) in renal HSP70 expression. T cells isolated from the spleens demonstrated a significant two-to nine-fold response compared to controls (Po0.05 or lower for each comparison) when cultured with HSP70. These studies suggest that autoimmunity to stress proteins is involved in the sustained low-grade inflammatory infiltration that occurs in the tubulointerstitial areas of the hypertensive kidney.

Research paper thumbnail of Migration inhibition factor in acute serum sickness nephritis

Kidney International, 1990

Migration inhibition factor in acute serum sickness nephritis. Monocytes have been demonstrated t... more Migration inhibition factor in acute serum sickness nephritis. Monocytes have been demonstrated to play an important role in acute serum sickness (AcSS) nephritis. Because accumulation of monocytes within the glomeruli could be the result of local lymphokine production, we studied migration inhibition factor (MIF) activity in supernatants from glomerular cultures, analyzed its temporal relationship with monocyte and lymphocyte accumulation, and tested the effect of anti-T lymphocyte monoclonal antibody on local MIF production. AcSS was induced in 12 rabbits, and one additional rabbit had antigen elimination without proteinuria. Single nephrectomy was performed at the time of antigen elimination in all animals; the remaining kidney was removed four days (4 rabbits) or 14 days afterwards (5 rabbits). In glomerular cross sections (gcs), lymphocytes were identified using monoclonal antibody M108, and monocytes by nonspecific esterase stain (ES). MIF activity was determined in supernatants of cultures of isolated glomeruli by the agarose microdroplet method. Peak of MIF activity (84.3 2,6%, 5EM) was observed the first day of proteinuna in association with peak of lymphocyte infiltration (1.15 0.1 lymphocytes/gcs) and monocyte infiltration (2.4 0.3 mean ES score/gcs). MIF activity diminished by day 4(66.0 6.3%) and reached control levels by day 14(12.8 3.2%). There was a significant correlation between lymphocyte infiltration and MIF activity (r = 0.776, P < 0.0001) as well as between MIF activity and monocyte accumulation (r = 0.858, P < 0.0001). In five additional rabbits with AcSS, glomeruli were isolated, treated successively with Ml08 and normal rabbit serum, and supernatants harvested from 24-hour cultures were tested for MIF activity. Negative controls were supernatants treated with TI-lytic monoclonal antibody, as well as untreated glomerular cultures. MIF activity from untreated and TI-lytic treated glomerular cultures was similar. Addition of M108 monoclonal antibody to glomerular cultures produced 70 12.9% inhibition of MIF activity. Our data suggest that lymphocytes infiltrating the glomeruli in AcSS produce lymphokines (MIF) which are related to the monocyte accumulation. Monocytes may play a significant role in the pathogenesis of acute glomerulonephritis since they are capable of secreting a variety of phlogogenic products [reviewed in 1] that may produce damage in several structures within the glomeruli. A series of recent experiments have shown that monocytes infiltrate this structure in experimental acute serum sickness (AcSS) [2, 3] and in human proliferative glomerulonephritides [4-6]. Three possible mechanisms have been suggested to account for the intraglomerular infiltration of monocytes: first, immune adherence of monocytes to the Fc portion of immuno

Research paper thumbnail of Antibody to streptococcal zymogen in the serum of patients with acute glomerulonephritis: A multicentric study

Kidney International, 1998

Cationic streptococcal proteinase (erythrotoxin B) and its precursor, zymogen, are putative nephr... more Cationic streptococcal proteinase (erythrotoxin B) and its precursor, zymogen, are putative nephritogenic antigens. The present study was designed to test whether serum titers to these antigens were good markers of streptococcal infection associated with glomerulonephritis. We studied 153 patients (male/female = 104/49, age range, 2 to 23 years old) with acute poststreptococcal glomerulonephritis (APSGN) from three countries (Venezuela, Chile and Argentina). The site of the initial infection was the skin in 84 patients, the throat in 55 patients and was unknown in 14 patients. In addition, we studied 23 patients (1 to 24 years old) with streptococcal infection not associated with glomerulonephritis (14 patients with impetigo and 9 patients with pharyngitis). As control group, 93 healthy individuals (54 males, 2 to 19 years old) were studied. Anti-zymogen and anti-proteinase titers were determined in a single laboratory by ELISA, and the intra- and interassay coefficients of variation were 5.3% and 8.5%, respectively. ASO titers and anti-DNAse B titers were also done. Anti-zymogen titers of 1:800 to 1:3200 had likelihood ratios (sensitivity/1-specificity) for detection of streptococcal infection in APSGN patients ranging from 2.00 to 44.2 in Argentina, Chile and Venezuela. Anti-zymogen titers decreased one to two months after APSGN and they were 1 to 3 log2 dilutions higher that anti-proteinase titers. Receiver operating characteristic (ROC) curves showed that anti-zymogen titers were consistently superior to anti-streptolysin O and anti-DNAse B titers as markers for streptococcal infection in APSGN. These results suggest that increased anti-zymogen antibody titers are the best available marker for streptococcal infection associated with acute glomerulonephritis.

Research paper thumbnail of Atrial natriuretic factor in the acute nephritic and nephrotic syndromes

Kidney International, 1990

Because the role of systemic hormones in the pathophysiology of edema in acute renal disease rema... more Because the role of systemic hormones in the pathophysiology of edema in acute renal disease remains incompletely understood, we compared the levels of atrial natriuretic factor (ANF) and plasma renin activity (PRA) in patients with acute glomerulonephritis (AGN), nephrotic syndrome (NS), and normal individuals during salt deprivation and salt loading. Sixteen patients with AGN (10 males) and nine patients with NS and hypoalbuminemia (7 males) were studied on admission, and after recovery (12 AGN patients) or remission (4 NS patients). Eighteen normal controls were each studied after five days on a low (20 mEq Na/day), regular (120 mEq Na/day) and high (300 mEq Na/day) dietary salt intake. Patients with AGN and NS had comparable edema (AGN 2.8 +/- 0.53 kg; NS 3.36 +/- 0.47 kg; SE) and urinary Na excretion (mean +/- SEM: AGN 0.97 +/- 0.11 mEq/hr; NS 1.06 +/- 0.16 mEq/hr), but AGN patients had five times higher ANF (AGN 27.2 +/- 4.06 fmol/ml; NS 5.51 +/- 1.02 fmol/ml; P less than 0.001) and six times lower PRA ng/liter.sec levels (AGN 0.187 +/- 0.047; NS 1.144 +/- 0.222; P less than 0.001) than NS patients. The degree of edema was correlated with ANF levels in AGN patients (P less than 0.001) but not in NS patients. There was a strong exponential negative correlation (r = -0.773, P less than 0.0001) between ANF and PRA, in which AGN patients and Na-restricted controls were located in the opposite ends of the volume sensing-response, and NS patients in the middle, alongside controls with regular Na intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of Mycophenolate mofetil prevents salt-sensitive hypertension resulting from angiotensin II exposure

Kidney International, 2001

Conclusions. SSHTN resulting from Ang II infusion is asso-Mycophenolate mofetil prevents salt-sen... more Conclusions. SSHTN resulting from Ang II infusion is asso-Mycophenolate mofetil prevents salt-sensitive hypertension ciated with infiltration and activation of immune cells that resulting from angiotensin II exposure. produce Ang II. MMF treatment reduces these features and Background. Interstitial mononuclear cell infiltration is a prevents the development of SSHTN. feature of experimental models of salt-sensitive hypertension (SSHTN). Since several products of these cells are capable of modifying local vascular reactivity and sodium reabsorption, we investigated whether mycophenolate mofetil (MMF), a drug Lombardi et al have recently reported that pressor known to inhibit infiltration and proliferation of immune cells, doses of angiotensin II (Ang II) administered for two would modify the SSHTN induced by angiotensin II (Ang II) infusion. weeks resulted in the subsequent development of salt-Methods. Sprague-Dawley rats received Ang II for two weeks sensitive hypertension (SSHTN) in the rat [1]. This invesusing subcutaneous minipumps. A high-sodium (4% NaCl) diet tigation established an experimental model that permits was started on the third week and was maintained until the the analysis of the sequential structural changes in the eighth week. MMF (30 mg/kg, N ϭ 15), an immunosuppressive drug, or vehicle (N ϭ 15) was given daily by gastric gavage kidney that are acutely induced by Ang II as well as with during the initial three weeks. Sham-operated rats (N ϭ 9) the development of persistent SSHTN. The structural were used as controls. Body weight, blood pressure (tail-cuff changes present in the kidney consist of focal vascular plethysmography), and serum creatinine were determined and tubulointerstitial damage with areas of tubular atroweekly. Urinary malondialdehyde (MDA) excretion, renal hisphy and a reduction in peritubular capillaries, while in tology, and immunohistology, including the presence of Ang II and superoxide-producing cells, were analyzed at the end of contrast, the glomeruli were minimally abnormal. These Ang II infusion and at eight weeks. findings supported the postulate that impairment of pres-Results. MMF treatment did not modify hypertension insure-natriuresis response caused by tubulointerstitial induced during exogenous Ang II infusion, but prevented the jury could play a pivotal role in the development of subsequent SSHTN. Tubulointerstitial injury resulting from Ang II infusion was significantly reduced by MMF treatment, hypertension in a variety of clinical conditions [2]. as were proliferative activity, T-cell infiltration and activation Nevertheless, histologic findings in the studies of Lom-(interleukin-2 receptor expression), superoxide-producing cells, bardi et al as well as in a variety of other experimental and urinary MDA excretion. Ang II-producing cells were presand clinical conditions associated with SSHTN include ent in the renal tubulointerstitium of rats with SSHTN (60 Ϯ infiltration, at times prominent, of mononuclear cells in 30 Ang II-positive cells/mm 2 at 8 weeks) and were reduced by two thirds in the MMF-treated group. Forty percent of tubulointerstitial areas of the kidney [1]. Examples of lymphocytes infiltrating the tubulointerstitium stained positive mononuclear cell infiltration in other experimental hyfor Ang II. The expression of Ang II receptors in the kidney pertension models include the "vicious cycle" of twowas unmodified.

Research paper thumbnail of Mycophenolate mofetil prevents the progressive renal failure induced by 5/6 renal ablation in rats

Kidney International, 1999

tration with CD43-and ED1-positive cells in glomeruli and Mycophenolate mofetil prevents the prog... more tration with CD43-and ED1-positive cells in glomeruli and Mycophenolate mofetil prevents the progressive renal failure interstitium was two to five times lower in MMF-treated rats induced by 5/6 renal ablation in rats. (P Ͻ 0.01). Expression of adhesion molecules CD18 and CD11b Background. Extensive renal ablation is associated with prowas similarly reduced. gressive sclerosis of the remnant kidney. Because lymphocytes Conclusion. MMF ameliorates the progressive renal damage and monocytes accumulate in the remnant kidney, it is likely that they play a role in the renal scarring. Therefore, we treated in the remnant kidney after 5/6Nx. This effect is associated with rats with 5/6 nephrectomy (5/6Nx) with mycophenolate mofetil a reduction in the infiltration of lymphocytes and monocytes, (MMF), a drug that has an antiproliferative effect and that whereas glomerular hypertrophy and systemic hypertension suppresses the expression of intercellular adhesion molecules. are unchanged. Methods. Sprague-Dawley rats with 5/6Nx received MMF (30 mg • kg Ϫ1 • day Ϫ1 by daily gastric gavage, N ϭ 15) or vehicle (N ϭ 16). Ten additional rats were sham operated. All rats The progression of renal damage resulting from rewere fed a 30% protein diet. Body weight, serum creatinine, and urinary protein excretion were determined weekly. Lipid duced nephron mass has been extensively studied in the peroxidation, as a measure of oxidative stress observed by 5/6Nx model in the rat, as described originally by Shimaurinary malondialdehyde determinations, was performed every mura and Morrison [1]. Classic studies by Hostetter et two weeks. Histologic studies were done in the remnant kidney al demonstrated that this experimental model was charfour weeks (9 rats from the vehicle-treated group, 7 rats from acterized by progressive glomerulosclerosis and chronic the MMF group, and 5 sham-operated rats) and eight weeks after surgery (the remaining rats). Glomerular volume, sclerorenal failure [2]. The remnant nephron units developed sis in glomeruli (segmental and global) and interstitium (semiglomerular hypertension, increased single nephron gloquantitative scale), infiltrating lymphocytes and macrophages merular filtration rate, and glomerular hypertrophy, and (CD43-and ED1-positive cells), and expression of adhesion over the previous 15 years, all of these factors have been molecules (CD54, CD18, and CD11b) were analyzed. postulated to play a pathogenetic role in the progressive Results. MMF treatment prevented the progressive increment in serum creatinine and the proteinuria observed in the scarring of the kidney [3]. Surviving nephrons have in-5/6 nephrectomized rats during the eight weeks of observation creased oxygen consumption and are subjected to oxi-(P Ͻ 0.01). Weight gain was comparable in the MMF-treated dant stress [4]. and sham-operated rats, whereas weight gain was decreased Because the initial event in the subtotal renal ablation in untreated 5/6 nephrectomized rats. Excretion of malondialdehyde increased after surgery but returned sooner to control model is an increase in glomerular pressure, treatment levels in the MMF-treated rats. Increments in glomerular size strategies have usually been directed to correct this heand mean arterial blood pressure induced by renal ablation modynamic disturbance, specifically, to reduce intrawere not modified by MMF treatment. Eight weeks after surglomerular pressure. Correction of this pathophysiologic gery, segmental sclerosis was present in 48.4 Ϯ 8.35% (Ϯ sd) event and normalization of permselectivity properties of glomeruli in the vehicle-treated group versus 25 Ϯ 10.5% in the MMF-treated group (P Ͻ 0.001). Interstitial fibrosis was the glomerular capillary barrier [5] are major mechareduced significantly with MMF treatment (P Ͻ 0.001). Infilnisms underlying the protective effect on renal function observed with angiotensin-converting enzyme inhibition and low-protein diet in several models of renal disease

Research paper thumbnail of Atrial natriuretic peptide levels in brain venous outflow during cardiopulmonary bypass in humans: Evidence for extracardiac hormonal production

Journal of Cardiothoracic and Vascular Anesthesia, 1991

Atrial natriuretic peptide (ANP) is a hormone with an important role in the regulation of extrace... more Atrial natriuretic peptide (ANP) is a hormone with an important role in the regulation of extracellular fluid volume. The ANP gene is not only expressed in the heart, but the high concentration of ANP in cardiac blood makes it difficult to demonstrate extraatrial hormonal secretion in vivo. This issue was addressed during complete cardiopulmonary bypass (CPB) in 13 patients undergoing elective cardiac surgery in whom ANP concentrations were followed in the internal jugular vein, representing largely brain venous outflow, as well as a peripheral vein and radial artery, after the heart and lungs were excluded from circulation. Plasma ANP levels in the peripheral venous circulation showed no significant changes during extracorporeal circulation, although they tended to decrease (from 6.76 f 2.16 fmol/mL to 4.76 2 0.69 fmol/mL; P > 0.06). ANP levels in the radial artery decreased significantly after the exclusion of the heart (from 16.64 2 3.51 fmol/mL to 6.63 2 0.97 fmol/mL; P < 0.01). In contrast, ANP concentration in the internal jugular vein increased in 12 of 13

Research paper thumbnail of Expression of Adhesion Molecules in Chronic Serum Sickness in Rats

Clinical Immunology, 1999

Peripheral blood leukocytes infiltrate the kidney in chronic serum sickness (CSS). We therefore s... more Peripheral blood leukocytes infiltrate the kidney in chronic serum sickness (CSS). We therefore studied the expression of CD54 and its ligands CD18 and CD11b/c in CSS in 10 rats with CSS, 6 rats immunized similarly who did not developed proteinuria (no-CSS group), and 10 normal rats (control group). Intense (6 to 35 times more than controls) leukocyte infiltration was observed in CSS. The CSS group over-expressed CD54 in glomeruli and interstitium in association with increments in CD18-and CD11b/c-positive cells ranging 2.5 to 7 times the number found in controls. 75% of infiltrating leukocytes expressed CD18 and 87% expressed CD11b/c. The non-CSS group had leukocyte infiltration and expression of adhesion molecules similar to control group. Adherence of CD43-positive cells to renal tissues was 4 times higher in renal tissue from CSS rats than to normal kidney. Pretreatment with corresponding Mabs reduced adherence by half. We concluded that over-expression of CD54 and its ligands CD18 and CD11b/c in infiltrating leukocytes occur in CSS. Binding experiments suggest the functional relevance of these molecules.

Research paper thumbnail of Cyclosporin A reduces expression of adhesion molecules in the kidney of rats with chronic serum sickness

Clinical and Experimental Immunology, 2000

Treatment with cyclosporin A (CsA) improves proteinuria and reduces renal cellular infiltration i... more Treatment with cyclosporin A (CsA) improves proteinuria and reduces renal cellular infiltration in chronic serum sickness (CSS). We examined if these effects were associated with a reduced renal expression of CD54 and its ligands, interferon-gamma (IFN-g), tumour necrosis factor-alpha (TNF-a) and MHC class II molecules. We studied two groups of rats in which CSS was induced by daily injections of ovalbumin (OVA): a group treated with CsA (OVA.CsA group, n 11) and a group that received no treatment (OVA.CSS group, n 11). An additional group of five rats (control group) received only phosphate buffer. Immunostaining techniques were used to follow CSS and to study the expression of CD54, CD18, CD11b/c, IFN-g, TNF-a and MHC class molecules. Proteinuria (mg/24 h) was reduced from 248´2^73´1 (OVA.CCS group) to 14´5^13´1 with CsA treatment (P , 0´0001). The renal expression of CD54 and its ligands (CD18 and CD11b/c) was reduced by 50% to 75%. Correspondingly, there was a 60% to 85% reduction in the number of infiltrating leucocytes. The number of cells expressing TNF-a , IFN-g and MHC II molecules was also reduced. CsA reduces expression of CD54 and its ligands. This effect is associated with a reduction of cellular infiltration, IFNg, TNF-a-producing cells and with MHC II expression in the kidney. These findings suggest that expression of adhesion molecules plays a critical role in CSS and underline the importance of cellular immunity in this experimental model.

Research paper thumbnail of Effect of Uric Acid on Gentamicin-Induced Nephrotoxicity in Rats - Role of Matrix Metalloproteinases 2 and 9

Basic & Clinical Pharmacology & Toxicology, 2009

In this work, we aimed to study the effect of uric acid on gentamicin-induced nephrotoxicity. Mal... more In this work, we aimed to study the effect of uric acid on gentamicin-induced nephrotoxicity. Male Sprague-Dawley rats were assigned to one of six groups (six rats each) which received intraperitoneal injections for 9 days: (S) saline; (UA) Uric acid alone; (G) Gentamicin alone; (G + UA) Gentamicin + uric acid; (G rec) Gentamicin recovery and (G + UA rec) Gentamicin + uric acid recovery. In (G rec) and (G + UA rec), rats recovered for 7 days after the last injection. Urine and blood samples were taken on day 0 and at the end of every stage. Kidneys were harvested for histological scoring, determination of renal malondialdehyde (MDA), zymography and western blots for matrix metalloprotease (MMP)-2 and MMP-9. Uric acid alone did not provoke changes in biochemical and histological parameters when compared to controls. Gentamicin alone increased significantly plasma creatinine and blood urea nitrogen and caused a moderate histological damage. When combined with uric acid, these conditions worsened. MMP-9 activity and expression was decreased in rats from group G + UA as compared with rats from group G, while activity of MMP-2 was similarly increased in both groups when compared to controls. The increase in renal MDA induced by gentamicin was not altered when it was combined with uric acid. During the recovery stage, all biochemical parameters returned to normal levels, though a trend for delay of tubular damage recovery was observed in group G + UA rec when compared with group G rec. The results indicate that uric acid worsens gentamicin-induced nephrotoxicity. The mechanism is likely to implicate down-regulation of MMP-9.

Research paper thumbnail of Mycophenolate mofetil treatment reduces cholesterol-induced atherosclerosis in the rabbit

Atherosclerosis, 2000

Immunosuppressive therapy has been shown to either improve or, more frequently, enhance the devel... more Immunosuppressive therapy has been shown to either improve or, more frequently, enhance the development of atherosclerosis. We tested the effect of mycophenolate mofetil (MMF), an inhibitor of nucleotide synthesis widely used in transplant therapy, in diet-induced atherosclerosis in the rabbit. Two groups (n= 10 each) of New Zealand White (NZW) rabbits were fed a 1% cholesterol diet for 12 weeks. One group received MMF (CHOL +MMF group) by gastric gavage (30 mg/kg daily) and the other group (CHOL) received the same volume of saline by the same route. There were no differences in the serum cholesterol (mean values ]30 mmol/l in both groups after 2 weeks) or in the triglyceride, blood sugar, total protein, and albumin serum levels and weight gain in both groups of animals. The cholesterol-fed untreated rabbits had atherosclerotic plaques covering 43.9.1 9SD 16.40% of their thoracic aorta and 41.9 922.59% of their abdominal aorta, while the MMF treated group had 18.5 97.17% and 17.7 9 9.71%, respectively (PB 0.01). The cholesterol content of the aorta (mg/g) in the cholesterol-fed untreated group was 4.61 9 SD 1.21 in the thoracic aorta and 4.54 92.07 in the abdominal aorta, whereas the MMF treated group had and 2.83 9 0.84 and 2.77 91.44, respectively (P B0.01). Infiltrating macrophages (RAM 11 positive cells/100 nuclei) in the intimal layer of the aorta were 58.4 9SD26.16 in the CHOL group and 8.595.51 in the CHOL+MMF group: (P B0.001). CD18 positive cells/100 nuclei were 27.4 917.6 in the CHOL group and 5.3 93.82 in the CHOL + MMF group (P B0.01), and the intima/media ratio was 0.6690.11 in the CHOL group and 0.309 0.09 in the MMF treated rabbits (PB 0.001). MMF also reduced proliferating smooth muscle cells (HHF35 positive) infiltrating between the macrophages. These results indicate that MMF ameliorates importantly the atherogenic potential of a high cholesterol diet and this effect is associated with a reduction in macrophage and foam cell infiltration and smooth muscle cell proliferation and infiltration. Since chronic treatment with this drug is given routinely in various clinical conditions with relatively minor side effects, consideration may be given to its use as adjuvant therapy in artheriosclerotic cardiovascular disease.

Research paper thumbnail of Immune reactivity to heat shock protein 70 expressed in the kidney is cause of salt-sensitive hypertension

American Journal of Physiology-Renal Physiology, 2012

Hypertension affects one-third of the adult population of the world. The causes of hypertension a... more Hypertension affects one-third of the adult population of the world. The causes of hypertension are incompletely understood, but relative impairment of sodium excretion is central to its pathogenesis. Immune cell infiltration in the kidney is a constant finding in hypertension that in association with local angiotensin and oxidants causes a defect in sodium excretion. However, it is unclear if the T cell influx into the kidney responds to nonspecific chemokine cues or is due to antigen-driven immune attraction. We found that T cells in experimentally induced salt-driven hypertension present a CD4 clonal response to heat shock protein 70 (HSP70) that is overexpressed in the kidney. We used a highly preserved amino acid sequence within the HSP molecule to induce immune tolerance associated with the generation of IL-10 producing regulatory T cells. Immune tolerant rats to HSP70 developed minimal renal inflammation and were protected from the development of salt-sensitive hypertension. ...

Research paper thumbnail of Evolution of Renal Interstitial Inflammation and NF-κB Activation in Spontaneously Hypertensive Rats

American Journal of Nephrology, 2004

Lymphocytes and macrophages infiltrate the kidney of spontaneously hypertensive rats (SHR) and in... more Lymphocytes and macrophages infiltrate the kidney of spontaneously hypertensive rats (SHR) and interventions leading to their reduction are associated with improvement of the hypertension. The present studies examined the evolution of the interstitial inflammation in the natural course of the SHR to gain insight on the potential role of interstitial immune cell accumulation in the development of hypertension. We studied SHR and control WKY rats at 3 weeks (SHR-3wk group, n = 11 and WKY-3wk group, n = 10), 11 weeks (SHR-11wk group, n = 5 and WKY-11wk group, n = 5) and 24 weeks (SHR-24wk group, n = 10 and WKY-24wk group, n = 10). The SHR-3wk group was normotensive and older SHR developed hypertension that was severe in the SHR-24wk group. Tubulointerstitial accumulation of lymphocytes, macrophages, angiotensin II-positive cells, cells expressing the p65 DNA-binding subunit of NF-ĸB and activation of NF-ĸB in the kidney were all significantly increased (p < 0.01) in the prehypertens...

Research paper thumbnail of Quantum dot effects upon the interaction between porphyrins and phospholipids in cell membrane models

European biophysics journal : EBJ, Jan 30, 2015

This study employed surface pressure isotherms and spectroscopic techniques to investigate the ef... more This study employed surface pressure isotherms and spectroscopic techniques to investigate the effect of quantum dots on the interaction between porphyrins and phospholipids using Langmuir monolayers and Langmuir-Blodgett films formed from negatively charged DMPA (the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid) and zwitterionic DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) as cell membrane models in the presence of 5,10,15,20-tetrakis(4-N-tetradecyl-pyridyl) porphyrin (TMPyP), 5,10,15,20-tetrakis(p-sulfonato-phenyl) porphyrin (TPPS4) and PEG-coated CdSe/ZnS quantum dots (QD). The porphyrins present at the monolayer subphase affected the organization of the lipids at the air/liquid interface, as shown by the changes in the surface pressure-surface area isotherms. QDs enhanced the interaction of TMPyP with DMPA, improving their transference from the liquid monolayers to solid supports. A higher amount of TMPyP was transferred to DMPA-Langmuir-Blodgett films when the ...

Research paper thumbnail of Melatonin attenuates acute renal failure and oxidative stress induced by mercuric chloride in rats

American Journal of Physiology-Renal Physiology, 2000

We evaluated the effect of melatonin (Mel), a potent scavenger of reactive oxygen species, in the... more We evaluated the effect of melatonin (Mel), a potent scavenger of reactive oxygen species, in the course of HgCl2-induced acute renal failure. Rats received by gastric gavage 1 mg/kg of Mel ( n = 21) or vehicle ( n = 21), 30 min before the subcutaneous injection of HgCl2(2.5 mg/kg). Rats were killed at 24, 48, and 72 h, and plasma creatinine (Scr), renal histology, proliferative activity, apoptosis, and superoxide-producing cells were studied. We also determined the renal content of malondialdehyde (MDA) and glutathione (GSH) and the activities of glutathione peroxidase and catalase. Mel pretreatment (Mel plasma levels of 3.40 ± 3.15 μg/ml at the time of HgCl2injection) prevented the increment in Scrand reduced tubular necrosis from 41.0 ± 10.5 to 4.2 ± 5.1% of proximal tubules ( P < 0.01). Apoptosis and postnecrotic proliferative activity were twice more intense in the group untreated with Mel. Increment in renal content of MDA and decrease in GSH resulting from HgCl2toxicity we...

Research paper thumbnail of Effect of uric acid on nephrotoxicity induced by mercuric chloride in rats

Toxicology and Industrial Health, 2010

Oxidative stress is an important mechanism in mercury poisoning. We studied the effect of uric ac... more Oxidative stress is an important mechanism in mercury poisoning. We studied the effect of uric acid, a natural and potent reactive oxygen species and peroxynitrite scavenger, in HgCl 2-induced nephrotoxicity. Rats were injected with a unique dose of HgCl2 (2.5 mg/kg body weight, subcutaneously) and then vehicle (for 3 days, twice daily) or HgCl2 (unique dose) and intraperitoneal uric acid suspension (250 mg/kg body weight, twice daily, for 3 days), and then killed at 24, 48 and 72 hours after HgCl2 administration (n = 5 for each group). At the end of the experimental study, kidneys and blood samples were taken. Tissues were prepared and examined under light microscopy. Uric acid significantly prevented the increase in plasma levels of creatinine and blood urea nitrogen (BUN); it helped maintain systemic nitrate/nitrite concentration and total antioxidant capacity. Uric acid attenuated the increase of renal lipid peroxidation and it markedly diminished nitrotyrosine signal and histop...

Research paper thumbnail of Cell populations and membrane attack complex in glomeruli of patients with post-streptococcal glomerulonephritis: Identification using monoclonal antibodies by indirect immunofluorescence

Clinical Immunology and Immunopathology, 1984

Poststreptococcal glomerulonephritis (PSGN) had been thought to arise from renal deposition of im... more Poststreptococcal glomerulonephritis (PSGN) had been thought to arise from renal deposition of immune complexes and as such is analogous to acute serum sickness. Recent studies of acute serum sickness in animals and PSGN in humans, however, have suggested a pathogenetic role for cellular immunity. To enlarge on these observation?. cellular components of glomeruli were characterized by indirect immunofluorescence in Ii tissues from individuals with PSGN using monoclonal antibodies. These studies demonstrate infiltration of glomeruli by monocytes, granulocytes. and lymphoid cells. Focal accumulations of T lymphocytes were also observed adjacent to Bowman's capsule. Analysis of glomerular T-cell subpopulations revealed a predominance of cells reactive with OKT4 early and with OKT8 later in the course of disease. Proliferation of parietal and visceral epithelial cells was associated with increased binding of BA-I and J.5, respectively. The presence of the membrane attack complex of complement was demonstrated by glomerular reactivity with a monoclonal antibody (poly-CY MA) which recognizes a neoantigen present in poly-C9. Fluorescence was present along the glomerular basement membrane early and within the mesangium late in the course of disease. a distribution similar to that observed for C3 and C5. These observations suggest that immune cells as well as terminal components of complement either provoke or mark tissue injury in PSGN. Cl 1984 Academtc Prec\. Ini-' Under the tenure of a Fundaciti Grant.

Research paper thumbnail of Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric oxide inhibition

Kidney International, 2003

Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric... more Vimentin and heat shock protein expression are induced in the kidney by angiotensin and by nitric oxide inhibition. Background. Angiotensin II (Ang II) infusion and nitric oxide synthesis (NOS) inhibition with N-nitro-l-arginine-methylester (l-NAME) are experimental models of hypertension associated with renal inflammation and oxidative stress. To gain insight into the nature of the tubulointerstitial injury induced in these models, we studied lectin-binding specificities, vimentin expression, and heat shock protein (HSP) 60 and 70 in these experimental models. Methods. Sprague-Dawley rats received Ang II infusion (435 ng/kg/min) for 2 weeks by subcutaneous minipumps (Ang II group, N ϭ 5) or l-NAME in the drinking water (70 mg/ 100 mL) for 3 weeks (l-NAME group N ϭ 7). The control group consisted of 10 rats. Systolic blood pressure (tail-cuff plethysmography), serum creatinine, and proteinuria were determined weekly. At the end of the treatment period, rats were sacrificed and kidneys studied. Binding specificities of fluorescein-labeled lectins were examined in frozen sections, and cellular infiltrates were identified by immunohistology and expression of vimentin and HSP 60 and 70 with immunohistochemistry and computer image analysis. Results. Tubulointerstitial accumulation of macrophages, lymphocytes, and Ang II-positive cells were present in the Ang II group and l-NAME group. Vimentin, HSP 60, and HSP 70 were increased 8 to 20 times in the cortex of the rats of the Ang II group and the l-NAME groups. Neoexpression of vimentin and HSPs was found primarily in proximal tubular cells. Conclusion. Ang II infusion and NOS inhibition induce tubular injury with epithelial cell transdifferentiation and expression of stress proteins. The role of these changes in the accumulation and activation of the interstitial inflammatory infiltrate merits further investigation.

Research paper thumbnail of Experimental induction of salt-sensitive hypertension is associated with lymphocyte proliferative response to HSP70

Kidney International, 2008

Renal tubulointerstitial inflammation is a constant feature of experimental models of hypertensio... more Renal tubulointerstitial inflammation is a constant feature of experimental models of hypertension and likely plays a role in the pathogenesis of salt-sensitive hypertension. We have previously raised the possibility that the immune cell infiltration is driven by a low grade autoimmune reactivity directed to or facilitated by renal heat shock protein over expression. The present studies were done to gain insight on possible cell-mediated immune mechanisms in experimental hypertension by determining the renal expression of HSP70 and the proliferation index of T lymphocytes cultured with HSP70. We studied male Sprague-Dawley rats with inhibition of nitric oxide (NO) synthase (n ¼ 6), protein overload (PO) proteinuria (n ¼ 7) and short-term angiotensin II (Ang II) infusion (n ¼ 5), and their corresponding control groups. Each model was associated with 2 to 4 fold increase (Po0.05-0.001) in renal HSP70 expression. T cells isolated from the spleens demonstrated a significant two-to nine-fold response compared to controls (Po0.05 or lower for each comparison) when cultured with HSP70. These studies suggest that autoimmunity to stress proteins is involved in the sustained low-grade inflammatory infiltration that occurs in the tubulointerstitial areas of the hypertensive kidney.

Research paper thumbnail of Migration inhibition factor in acute serum sickness nephritis

Kidney International, 1990

Migration inhibition factor in acute serum sickness nephritis. Monocytes have been demonstrated t... more Migration inhibition factor in acute serum sickness nephritis. Monocytes have been demonstrated to play an important role in acute serum sickness (AcSS) nephritis. Because accumulation of monocytes within the glomeruli could be the result of local lymphokine production, we studied migration inhibition factor (MIF) activity in supernatants from glomerular cultures, analyzed its temporal relationship with monocyte and lymphocyte accumulation, and tested the effect of anti-T lymphocyte monoclonal antibody on local MIF production. AcSS was induced in 12 rabbits, and one additional rabbit had antigen elimination without proteinuria. Single nephrectomy was performed at the time of antigen elimination in all animals; the remaining kidney was removed four days (4 rabbits) or 14 days afterwards (5 rabbits). In glomerular cross sections (gcs), lymphocytes were identified using monoclonal antibody M108, and monocytes by nonspecific esterase stain (ES). MIF activity was determined in supernatants of cultures of isolated glomeruli by the agarose microdroplet method. Peak of MIF activity (84.3 2,6%, 5EM) was observed the first day of proteinuna in association with peak of lymphocyte infiltration (1.15 0.1 lymphocytes/gcs) and monocyte infiltration (2.4 0.3 mean ES score/gcs). MIF activity diminished by day 4(66.0 6.3%) and reached control levels by day 14(12.8 3.2%). There was a significant correlation between lymphocyte infiltration and MIF activity (r = 0.776, P < 0.0001) as well as between MIF activity and monocyte accumulation (r = 0.858, P < 0.0001). In five additional rabbits with AcSS, glomeruli were isolated, treated successively with Ml08 and normal rabbit serum, and supernatants harvested from 24-hour cultures were tested for MIF activity. Negative controls were supernatants treated with TI-lytic monoclonal antibody, as well as untreated glomerular cultures. MIF activity from untreated and TI-lytic treated glomerular cultures was similar. Addition of M108 monoclonal antibody to glomerular cultures produced 70 12.9% inhibition of MIF activity. Our data suggest that lymphocytes infiltrating the glomeruli in AcSS produce lymphokines (MIF) which are related to the monocyte accumulation. Monocytes may play a significant role in the pathogenesis of acute glomerulonephritis since they are capable of secreting a variety of phlogogenic products [reviewed in 1] that may produce damage in several structures within the glomeruli. A series of recent experiments have shown that monocytes infiltrate this structure in experimental acute serum sickness (AcSS) [2, 3] and in human proliferative glomerulonephritides [4-6]. Three possible mechanisms have been suggested to account for the intraglomerular infiltration of monocytes: first, immune adherence of monocytes to the Fc portion of immuno

Research paper thumbnail of Antibody to streptococcal zymogen in the serum of patients with acute glomerulonephritis: A multicentric study

Kidney International, 1998

Cationic streptococcal proteinase (erythrotoxin B) and its precursor, zymogen, are putative nephr... more Cationic streptococcal proteinase (erythrotoxin B) and its precursor, zymogen, are putative nephritogenic antigens. The present study was designed to test whether serum titers to these antigens were good markers of streptococcal infection associated with glomerulonephritis. We studied 153 patients (male/female = 104/49, age range, 2 to 23 years old) with acute poststreptococcal glomerulonephritis (APSGN) from three countries (Venezuela, Chile and Argentina). The site of the initial infection was the skin in 84 patients, the throat in 55 patients and was unknown in 14 patients. In addition, we studied 23 patients (1 to 24 years old) with streptococcal infection not associated with glomerulonephritis (14 patients with impetigo and 9 patients with pharyngitis). As control group, 93 healthy individuals (54 males, 2 to 19 years old) were studied. Anti-zymogen and anti-proteinase titers were determined in a single laboratory by ELISA, and the intra- and interassay coefficients of variation were 5.3% and 8.5%, respectively. ASO titers and anti-DNAse B titers were also done. Anti-zymogen titers of 1:800 to 1:3200 had likelihood ratios (sensitivity/1-specificity) for detection of streptococcal infection in APSGN patients ranging from 2.00 to 44.2 in Argentina, Chile and Venezuela. Anti-zymogen titers decreased one to two months after APSGN and they were 1 to 3 log2 dilutions higher that anti-proteinase titers. Receiver operating characteristic (ROC) curves showed that anti-zymogen titers were consistently superior to anti-streptolysin O and anti-DNAse B titers as markers for streptococcal infection in APSGN. These results suggest that increased anti-zymogen antibody titers are the best available marker for streptococcal infection associated with acute glomerulonephritis.

Research paper thumbnail of Atrial natriuretic factor in the acute nephritic and nephrotic syndromes

Kidney International, 1990

Because the role of systemic hormones in the pathophysiology of edema in acute renal disease rema... more Because the role of systemic hormones in the pathophysiology of edema in acute renal disease remains incompletely understood, we compared the levels of atrial natriuretic factor (ANF) and plasma renin activity (PRA) in patients with acute glomerulonephritis (AGN), nephrotic syndrome (NS), and normal individuals during salt deprivation and salt loading. Sixteen patients with AGN (10 males) and nine patients with NS and hypoalbuminemia (7 males) were studied on admission, and after recovery (12 AGN patients) or remission (4 NS patients). Eighteen normal controls were each studied after five days on a low (20 mEq Na/day), regular (120 mEq Na/day) and high (300 mEq Na/day) dietary salt intake. Patients with AGN and NS had comparable edema (AGN 2.8 +/- 0.53 kg; NS 3.36 +/- 0.47 kg; SE) and urinary Na excretion (mean +/- SEM: AGN 0.97 +/- 0.11 mEq/hr; NS 1.06 +/- 0.16 mEq/hr), but AGN patients had five times higher ANF (AGN 27.2 +/- 4.06 fmol/ml; NS 5.51 +/- 1.02 fmol/ml; P less than 0.001) and six times lower PRA ng/liter.sec levels (AGN 0.187 +/- 0.047; NS 1.144 +/- 0.222; P less than 0.001) than NS patients. The degree of edema was correlated with ANF levels in AGN patients (P less than 0.001) but not in NS patients. There was a strong exponential negative correlation (r = -0.773, P less than 0.0001) between ANF and PRA, in which AGN patients and Na-restricted controls were located in the opposite ends of the volume sensing-response, and NS patients in the middle, alongside controls with regular Na intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of Mycophenolate mofetil prevents salt-sensitive hypertension resulting from angiotensin II exposure

Kidney International, 2001

Conclusions. SSHTN resulting from Ang II infusion is asso-Mycophenolate mofetil prevents salt-sen... more Conclusions. SSHTN resulting from Ang II infusion is asso-Mycophenolate mofetil prevents salt-sensitive hypertension ciated with infiltration and activation of immune cells that resulting from angiotensin II exposure. produce Ang II. MMF treatment reduces these features and Background. Interstitial mononuclear cell infiltration is a prevents the development of SSHTN. feature of experimental models of salt-sensitive hypertension (SSHTN). Since several products of these cells are capable of modifying local vascular reactivity and sodium reabsorption, we investigated whether mycophenolate mofetil (MMF), a drug Lombardi et al have recently reported that pressor known to inhibit infiltration and proliferation of immune cells, doses of angiotensin II (Ang II) administered for two would modify the SSHTN induced by angiotensin II (Ang II) infusion. weeks resulted in the subsequent development of salt-Methods. Sprague-Dawley rats received Ang II for two weeks sensitive hypertension (SSHTN) in the rat [1]. This invesusing subcutaneous minipumps. A high-sodium (4% NaCl) diet tigation established an experimental model that permits was started on the third week and was maintained until the the analysis of the sequential structural changes in the eighth week. MMF (30 mg/kg, N ϭ 15), an immunosuppressive drug, or vehicle (N ϭ 15) was given daily by gastric gavage kidney that are acutely induced by Ang II as well as with during the initial three weeks. Sham-operated rats (N ϭ 9) the development of persistent SSHTN. The structural were used as controls. Body weight, blood pressure (tail-cuff changes present in the kidney consist of focal vascular plethysmography), and serum creatinine were determined and tubulointerstitial damage with areas of tubular atroweekly. Urinary malondialdehyde (MDA) excretion, renal hisphy and a reduction in peritubular capillaries, while in tology, and immunohistology, including the presence of Ang II and superoxide-producing cells, were analyzed at the end of contrast, the glomeruli were minimally abnormal. These Ang II infusion and at eight weeks. findings supported the postulate that impairment of pres-Results. MMF treatment did not modify hypertension insure-natriuresis response caused by tubulointerstitial induced during exogenous Ang II infusion, but prevented the jury could play a pivotal role in the development of subsequent SSHTN. Tubulointerstitial injury resulting from Ang II infusion was significantly reduced by MMF treatment, hypertension in a variety of clinical conditions [2]. as were proliferative activity, T-cell infiltration and activation Nevertheless, histologic findings in the studies of Lom-(interleukin-2 receptor expression), superoxide-producing cells, bardi et al as well as in a variety of other experimental and urinary MDA excretion. Ang II-producing cells were presand clinical conditions associated with SSHTN include ent in the renal tubulointerstitium of rats with SSHTN (60 Ϯ infiltration, at times prominent, of mononuclear cells in 30 Ang II-positive cells/mm 2 at 8 weeks) and were reduced by two thirds in the MMF-treated group. Forty percent of tubulointerstitial areas of the kidney [1]. Examples of lymphocytes infiltrating the tubulointerstitium stained positive mononuclear cell infiltration in other experimental hyfor Ang II. The expression of Ang II receptors in the kidney pertension models include the "vicious cycle" of twowas unmodified.

Research paper thumbnail of Mycophenolate mofetil prevents the progressive renal failure induced by 5/6 renal ablation in rats

Kidney International, 1999

tration with CD43-and ED1-positive cells in glomeruli and Mycophenolate mofetil prevents the prog... more tration with CD43-and ED1-positive cells in glomeruli and Mycophenolate mofetil prevents the progressive renal failure interstitium was two to five times lower in MMF-treated rats induced by 5/6 renal ablation in rats. (P Ͻ 0.01). Expression of adhesion molecules CD18 and CD11b Background. Extensive renal ablation is associated with prowas similarly reduced. gressive sclerosis of the remnant kidney. Because lymphocytes Conclusion. MMF ameliorates the progressive renal damage and monocytes accumulate in the remnant kidney, it is likely that they play a role in the renal scarring. Therefore, we treated in the remnant kidney after 5/6Nx. This effect is associated with rats with 5/6 nephrectomy (5/6Nx) with mycophenolate mofetil a reduction in the infiltration of lymphocytes and monocytes, (MMF), a drug that has an antiproliferative effect and that whereas glomerular hypertrophy and systemic hypertension suppresses the expression of intercellular adhesion molecules. are unchanged. Methods. Sprague-Dawley rats with 5/6Nx received MMF (30 mg • kg Ϫ1 • day Ϫ1 by daily gastric gavage, N ϭ 15) or vehicle (N ϭ 16). Ten additional rats were sham operated. All rats The progression of renal damage resulting from rewere fed a 30% protein diet. Body weight, serum creatinine, and urinary protein excretion were determined weekly. Lipid duced nephron mass has been extensively studied in the peroxidation, as a measure of oxidative stress observed by 5/6Nx model in the rat, as described originally by Shimaurinary malondialdehyde determinations, was performed every mura and Morrison [1]. Classic studies by Hostetter et two weeks. Histologic studies were done in the remnant kidney al demonstrated that this experimental model was charfour weeks (9 rats from the vehicle-treated group, 7 rats from acterized by progressive glomerulosclerosis and chronic the MMF group, and 5 sham-operated rats) and eight weeks after surgery (the remaining rats). Glomerular volume, sclerorenal failure [2]. The remnant nephron units developed sis in glomeruli (segmental and global) and interstitium (semiglomerular hypertension, increased single nephron gloquantitative scale), infiltrating lymphocytes and macrophages merular filtration rate, and glomerular hypertrophy, and (CD43-and ED1-positive cells), and expression of adhesion over the previous 15 years, all of these factors have been molecules (CD54, CD18, and CD11b) were analyzed. postulated to play a pathogenetic role in the progressive Results. MMF treatment prevented the progressive increment in serum creatinine and the proteinuria observed in the scarring of the kidney [3]. Surviving nephrons have in-5/6 nephrectomized rats during the eight weeks of observation creased oxygen consumption and are subjected to oxi-(P Ͻ 0.01). Weight gain was comparable in the MMF-treated dant stress [4]. and sham-operated rats, whereas weight gain was decreased Because the initial event in the subtotal renal ablation in untreated 5/6 nephrectomized rats. Excretion of malondialdehyde increased after surgery but returned sooner to control model is an increase in glomerular pressure, treatment levels in the MMF-treated rats. Increments in glomerular size strategies have usually been directed to correct this heand mean arterial blood pressure induced by renal ablation modynamic disturbance, specifically, to reduce intrawere not modified by MMF treatment. Eight weeks after surglomerular pressure. Correction of this pathophysiologic gery, segmental sclerosis was present in 48.4 Ϯ 8.35% (Ϯ sd) event and normalization of permselectivity properties of glomeruli in the vehicle-treated group versus 25 Ϯ 10.5% in the MMF-treated group (P Ͻ 0.001). Interstitial fibrosis was the glomerular capillary barrier [5] are major mechareduced significantly with MMF treatment (P Ͻ 0.001). Infilnisms underlying the protective effect on renal function observed with angiotensin-converting enzyme inhibition and low-protein diet in several models of renal disease

Research paper thumbnail of Atrial natriuretic peptide levels in brain venous outflow during cardiopulmonary bypass in humans: Evidence for extracardiac hormonal production

Journal of Cardiothoracic and Vascular Anesthesia, 1991

Atrial natriuretic peptide (ANP) is a hormone with an important role in the regulation of extrace... more Atrial natriuretic peptide (ANP) is a hormone with an important role in the regulation of extracellular fluid volume. The ANP gene is not only expressed in the heart, but the high concentration of ANP in cardiac blood makes it difficult to demonstrate extraatrial hormonal secretion in vivo. This issue was addressed during complete cardiopulmonary bypass (CPB) in 13 patients undergoing elective cardiac surgery in whom ANP concentrations were followed in the internal jugular vein, representing largely brain venous outflow, as well as a peripheral vein and radial artery, after the heart and lungs were excluded from circulation. Plasma ANP levels in the peripheral venous circulation showed no significant changes during extracorporeal circulation, although they tended to decrease (from 6.76 f 2.16 fmol/mL to 4.76 2 0.69 fmol/mL; P > 0.06). ANP levels in the radial artery decreased significantly after the exclusion of the heart (from 16.64 2 3.51 fmol/mL to 6.63 2 0.97 fmol/mL; P < 0.01). In contrast, ANP concentration in the internal jugular vein increased in 12 of 13

Research paper thumbnail of Expression of Adhesion Molecules in Chronic Serum Sickness in Rats

Clinical Immunology, 1999

Peripheral blood leukocytes infiltrate the kidney in chronic serum sickness (CSS). We therefore s... more Peripheral blood leukocytes infiltrate the kidney in chronic serum sickness (CSS). We therefore studied the expression of CD54 and its ligands CD18 and CD11b/c in CSS in 10 rats with CSS, 6 rats immunized similarly who did not developed proteinuria (no-CSS group), and 10 normal rats (control group). Intense (6 to 35 times more than controls) leukocyte infiltration was observed in CSS. The CSS group over-expressed CD54 in glomeruli and interstitium in association with increments in CD18-and CD11b/c-positive cells ranging 2.5 to 7 times the number found in controls. 75% of infiltrating leukocytes expressed CD18 and 87% expressed CD11b/c. The non-CSS group had leukocyte infiltration and expression of adhesion molecules similar to control group. Adherence of CD43-positive cells to renal tissues was 4 times higher in renal tissue from CSS rats than to normal kidney. Pretreatment with corresponding Mabs reduced adherence by half. We concluded that over-expression of CD54 and its ligands CD18 and CD11b/c in infiltrating leukocytes occur in CSS. Binding experiments suggest the functional relevance of these molecules.

Research paper thumbnail of Cyclosporin A reduces expression of adhesion molecules in the kidney of rats with chronic serum sickness

Clinical and Experimental Immunology, 2000

Treatment with cyclosporin A (CsA) improves proteinuria and reduces renal cellular infiltration i... more Treatment with cyclosporin A (CsA) improves proteinuria and reduces renal cellular infiltration in chronic serum sickness (CSS). We examined if these effects were associated with a reduced renal expression of CD54 and its ligands, interferon-gamma (IFN-g), tumour necrosis factor-alpha (TNF-a) and MHC class II molecules. We studied two groups of rats in which CSS was induced by daily injections of ovalbumin (OVA): a group treated with CsA (OVA.CsA group, n 11) and a group that received no treatment (OVA.CSS group, n 11). An additional group of five rats (control group) received only phosphate buffer. Immunostaining techniques were used to follow CSS and to study the expression of CD54, CD18, CD11b/c, IFN-g, TNF-a and MHC class molecules. Proteinuria (mg/24 h) was reduced from 248´2^73´1 (OVA.CCS group) to 14´5^13´1 with CsA treatment (P , 0´0001). The renal expression of CD54 and its ligands (CD18 and CD11b/c) was reduced by 50% to 75%. Correspondingly, there was a 60% to 85% reduction in the number of infiltrating leucocytes. The number of cells expressing TNF-a , IFN-g and MHC II molecules was also reduced. CsA reduces expression of CD54 and its ligands. This effect is associated with a reduction of cellular infiltration, IFNg, TNF-a-producing cells and with MHC II expression in the kidney. These findings suggest that expression of adhesion molecules plays a critical role in CSS and underline the importance of cellular immunity in this experimental model.

Research paper thumbnail of Effect of Uric Acid on Gentamicin-Induced Nephrotoxicity in Rats - Role of Matrix Metalloproteinases 2 and 9

Basic & Clinical Pharmacology & Toxicology, 2009

In this work, we aimed to study the effect of uric acid on gentamicin-induced nephrotoxicity. Mal... more In this work, we aimed to study the effect of uric acid on gentamicin-induced nephrotoxicity. Male Sprague-Dawley rats were assigned to one of six groups (six rats each) which received intraperitoneal injections for 9 days: (S) saline; (UA) Uric acid alone; (G) Gentamicin alone; (G + UA) Gentamicin + uric acid; (G rec) Gentamicin recovery and (G + UA rec) Gentamicin + uric acid recovery. In (G rec) and (G + UA rec), rats recovered for 7 days after the last injection. Urine and blood samples were taken on day 0 and at the end of every stage. Kidneys were harvested for histological scoring, determination of renal malondialdehyde (MDA), zymography and western blots for matrix metalloprotease (MMP)-2 and MMP-9. Uric acid alone did not provoke changes in biochemical and histological parameters when compared to controls. Gentamicin alone increased significantly plasma creatinine and blood urea nitrogen and caused a moderate histological damage. When combined with uric acid, these conditions worsened. MMP-9 activity and expression was decreased in rats from group G + UA as compared with rats from group G, while activity of MMP-2 was similarly increased in both groups when compared to controls. The increase in renal MDA induced by gentamicin was not altered when it was combined with uric acid. During the recovery stage, all biochemical parameters returned to normal levels, though a trend for delay of tubular damage recovery was observed in group G + UA rec when compared with group G rec. The results indicate that uric acid worsens gentamicin-induced nephrotoxicity. The mechanism is likely to implicate down-regulation of MMP-9.

Research paper thumbnail of Mycophenolate mofetil treatment reduces cholesterol-induced atherosclerosis in the rabbit

Atherosclerosis, 2000

Immunosuppressive therapy has been shown to either improve or, more frequently, enhance the devel... more Immunosuppressive therapy has been shown to either improve or, more frequently, enhance the development of atherosclerosis. We tested the effect of mycophenolate mofetil (MMF), an inhibitor of nucleotide synthesis widely used in transplant therapy, in diet-induced atherosclerosis in the rabbit. Two groups (n= 10 each) of New Zealand White (NZW) rabbits were fed a 1% cholesterol diet for 12 weeks. One group received MMF (CHOL +MMF group) by gastric gavage (30 mg/kg daily) and the other group (CHOL) received the same volume of saline by the same route. There were no differences in the serum cholesterol (mean values ]30 mmol/l in both groups after 2 weeks) or in the triglyceride, blood sugar, total protein, and albumin serum levels and weight gain in both groups of animals. The cholesterol-fed untreated rabbits had atherosclerotic plaques covering 43.9.1 9SD 16.40% of their thoracic aorta and 41.9 922.59% of their abdominal aorta, while the MMF treated group had 18.5 97.17% and 17.7 9 9.71%, respectively (PB 0.01). The cholesterol content of the aorta (mg/g) in the cholesterol-fed untreated group was 4.61 9 SD 1.21 in the thoracic aorta and 4.54 92.07 in the abdominal aorta, whereas the MMF treated group had and 2.83 9 0.84 and 2.77 91.44, respectively (P B0.01). Infiltrating macrophages (RAM 11 positive cells/100 nuclei) in the intimal layer of the aorta were 58.4 9SD26.16 in the CHOL group and 8.595.51 in the CHOL+MMF group: (P B0.001). CD18 positive cells/100 nuclei were 27.4 917.6 in the CHOL group and 5.3 93.82 in the CHOL + MMF group (P B0.01), and the intima/media ratio was 0.6690.11 in the CHOL group and 0.309 0.09 in the MMF treated rabbits (PB 0.001). MMF also reduced proliferating smooth muscle cells (HHF35 positive) infiltrating between the macrophages. These results indicate that MMF ameliorates importantly the atherogenic potential of a high cholesterol diet and this effect is associated with a reduction in macrophage and foam cell infiltration and smooth muscle cell proliferation and infiltration. Since chronic treatment with this drug is given routinely in various clinical conditions with relatively minor side effects, consideration may be given to its use as adjuvant therapy in artheriosclerotic cardiovascular disease.

Research paper thumbnail of Immune reactivity to heat shock protein 70 expressed in the kidney is cause of salt-sensitive hypertension

American Journal of Physiology-Renal Physiology, 2012

Hypertension affects one-third of the adult population of the world. The causes of hypertension a... more Hypertension affects one-third of the adult population of the world. The causes of hypertension are incompletely understood, but relative impairment of sodium excretion is central to its pathogenesis. Immune cell infiltration in the kidney is a constant finding in hypertension that in association with local angiotensin and oxidants causes a defect in sodium excretion. However, it is unclear if the T cell influx into the kidney responds to nonspecific chemokine cues or is due to antigen-driven immune attraction. We found that T cells in experimentally induced salt-driven hypertension present a CD4 clonal response to heat shock protein 70 (HSP70) that is overexpressed in the kidney. We used a highly preserved amino acid sequence within the HSP molecule to induce immune tolerance associated with the generation of IL-10 producing regulatory T cells. Immune tolerant rats to HSP70 developed minimal renal inflammation and were protected from the development of salt-sensitive hypertension. ...

Research paper thumbnail of Evolution of Renal Interstitial Inflammation and NF-κB Activation in Spontaneously Hypertensive Rats

American Journal of Nephrology, 2004

Lymphocytes and macrophages infiltrate the kidney of spontaneously hypertensive rats (SHR) and in... more Lymphocytes and macrophages infiltrate the kidney of spontaneously hypertensive rats (SHR) and interventions leading to their reduction are associated with improvement of the hypertension. The present studies examined the evolution of the interstitial inflammation in the natural course of the SHR to gain insight on the potential role of interstitial immune cell accumulation in the development of hypertension. We studied SHR and control WKY rats at 3 weeks (SHR-3wk group, n = 11 and WKY-3wk group, n = 10), 11 weeks (SHR-11wk group, n = 5 and WKY-11wk group, n = 5) and 24 weeks (SHR-24wk group, n = 10 and WKY-24wk group, n = 10). The SHR-3wk group was normotensive and older SHR developed hypertension that was severe in the SHR-24wk group. Tubulointerstitial accumulation of lymphocytes, macrophages, angiotensin II-positive cells, cells expressing the p65 DNA-binding subunit of NF-ĸB and activation of NF-ĸB in the kidney were all significantly increased (p < 0.01) in the prehypertens...

Research paper thumbnail of Quantum dot effects upon the interaction between porphyrins and phospholipids in cell membrane models

European biophysics journal : EBJ, Jan 30, 2015

This study employed surface pressure isotherms and spectroscopic techniques to investigate the ef... more This study employed surface pressure isotherms and spectroscopic techniques to investigate the effect of quantum dots on the interaction between porphyrins and phospholipids using Langmuir monolayers and Langmuir-Blodgett films formed from negatively charged DMPA (the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid) and zwitterionic DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) as cell membrane models in the presence of 5,10,15,20-tetrakis(4-N-tetradecyl-pyridyl) porphyrin (TMPyP), 5,10,15,20-tetrakis(p-sulfonato-phenyl) porphyrin (TPPS4) and PEG-coated CdSe/ZnS quantum dots (QD). The porphyrins present at the monolayer subphase affected the organization of the lipids at the air/liquid interface, as shown by the changes in the surface pressure-surface area isotherms. QDs enhanced the interaction of TMPyP with DMPA, improving their transference from the liquid monolayers to solid supports. A higher amount of TMPyP was transferred to DMPA-Langmuir-Blodgett films when the ...