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L H Toledo-Pereyra

Publications and source records attributed to L H Toledo-Pereyra.

At least 19 recordsLinked to original sources

Nitric oxide diminishes apoptosis and p53 gene expression after renal ischemia and reperfusion injury.

BACKGROUND: The role of nitric oxide in the ischemic injury of the kidney is still controversial. The aim of this study was to reevaluate the beneficial effect of exogenous nitric oxide and define its effects as regulator of gene p53 expression and apoptosis in the ischemic renal injury. METHODS: Sprague-Dawley rats were subjected to 75 min of renal warm ischemia and contralateral nephrectomy. The animals were divided into six groups (n=6 per group): Two sham groups at 4 and 24 hr, two ischemic control (IC) at same times and two treated groups (Na-NP), studied at same intervals, where sodium nitroprusside (5 mg/kg) was given 15 min before reperfusion. The parameters evaluated included: serum creatinine, blood urea nitrogen, neutrophil infiltration determined by myeloperoxidase, gene p53 expression determined by reverse transcriptase polymerase chain reaction, apoptosis determined by peroxidase in situ technique and light histology. RESULTS: There were significant improvements in serum creatinine and blood urea nitrogen at 24 hr in the NA-NP group when compared with the IC group (P<0.05). Myeloperoxidase levels were higher in the IC when evaluated against the Na-NP groups. Na-NP exhibited a downregulating effect in the expression of gene p53 when compared to the IC group. Apoptosis was more evident in the IC group and had moderately increased histological damage when compared to the Na-NP group. CONCLUSIONS: Nitric oxide demonstrated a protective effect in the ischemic injury of the kidney and exerted an antiapoptotic action dowregulating the expression of gene p53.

Animals↗

L-Selectin and chemokine response after liver ischemia and reperfusion.

BACKGROUND: L-selectin plays an important role in the early phase of PMNs recruitment in the hepatic microvasculature following liver ischemia and reperfusion (I/R). Leukocyte cytokine chemoattractants (chemokines) cause polymorphonuclear neutrophil (PMN) activation in I/R injury. In this study, we examined the role of L-selectin in the production of chemokines in the liver and lung inflammatory response following 90 min of warm ischemia. STUDY DESIGN: Thirty-six C57BL/6 mice were subjected to partial liver ischemia for a period of 90 min. Three groups of animals were included (n = 12 per group)-sham group, ischemic control, and the ischemic group receiving monoclonal antibody against L-selectin. We evaluated at 3 h: liver injury measurements, serum chemokines (MIP-2 and MIP-1alpha), liver and lung tissue myeloperoxidase (MPO), and liver and lung histology. Statistical analysis included ANOVA, Student-Newman-Keuls', and Kruskal-Wallis multiple comparison Z-value tests. RESULTS: The ischemic group treated with anti-L-selectin showed significant decreases in liver enzyme levels and a marked decrease in serum MIP-2 (P < 0.05) when compared to ischemic controls. No reduction in serum MIP-1alpha was noted; however, neutrophil infiltration was significantly ameliorated in the liver and in the lung, as reflected by decreased MPO levels (P < 0.05). Improved histopathological features were observed in the anti-L-selectin-treated group compared to ischemic controls in the liver and the lung. CONCLUSIONS: Our study suggests an important role for L-selectin in the pathogenesis of liver I/R and the production of chemokines. Anti-L-selectin treatment resulted in improved liver function, decreased neutrophil infiltration, and decreased MIP-2 chemokine response.

Animals↗

P-selectin and chemokine response after liver ischemia and reperfusion.

BACKGROUND: P-selectin plays a major role in the earliest phase of polymorphonuclear neutrophil recruitment in the hepatic microvasculature after liver ischemia and reperfusion. Leukocyte cytokine chemoattractants (chemokines) cause polymorphonuclear neutrophil activation in ischemia and reperfusion injury. In this study, we examined the role of P-selectin in the production of chemokines in the liver and lung inflammatory response after 90 minutes of warm ischemia. STUDY DESIGN: Thirty-six C57BL/6 mice were subjected to partial liver ischemia for 90 minutes. Three groups of animals were included (n = 12 per group): the sham group, the ischemic control group, and the P-selectin-deficient gene targeted mice group. After 3 hours, we evaluated liver injury measurements, serum chemokines (MIP[macrophage inflammatory protein]-1alpha and MIP-2), liver and lung tissue myeloperoxidase, and liver and lung histology. Statistical analysis included ANOVA, Student-Newman-Keuls', and Kruskal-Wallis Multiple Comparison Z-value tests. RESULTS: P-selectin-deficient mice showed significant decreases in liver enzyme levels (p < 0.05) and marked decreases in serum MIP-1alpha and MIP-2 chemokine determinations (p < 0.05) when compared with ischemic controls. Neutrophil infiltration was significantly ameliorated in the liver (p < 0.05) and markedly decreased in the lung, as reflected by decreased MPO levels. Improved histopathologic features in the liver and lung were observed in the P-selectin-deficient mice group compared with ischemic controls. CONCLUSIONS: Our study confirms the key role of P-selectin in the pathogenesis of liver ischemia and reperfusion and the production of chemokines. P-selectin-deficient animals had improved liver function, decreased neutrophil infiltration, and decreased MIP- 1alpha and MIP-2 responses.

Analysis of Variance↗

Multiple selectin blockade with a small molecule inhibitor downregulates liver chemokine expression and neutrophil infiltration after hemorrhagic shock.

BACKGROUND: The purpose of this study was to investigate the regulatory effect of a small molecule selectin inhibitor in the liver by examining the functional, structural, and survival response of animals subjected to hemorrhagic shock and to determine the liver infiltration of neutrophils and the regulation of chemokine expression. Selectins play an important role in the development of the lesions associated with ischemia/reperfusion and hemorrhagic shock. Blocking individually the selectin family of adhesion molecules with monoclonal antibodies has resulted in better organ function and survival. To our knowledge, there are no studies demonstrating the beneficial effect of multiple selectin blockade with a small molecule inhibitor under conditions of hemorrhagic shock. METHODS: Forty-eight Sprague-Dawley rats were subjected to hemorrhagic shock. Three groups of animals were included (n = 16/group), i.e., the sham, control, and treated groups, which received a small molecule selectin inhibitor (TBC-1269) at 25 mg/kg body weight after the bleeding began. The following parameters were evaluated: fluid requirements during resuscitation, liver injury tests (aspartate aminotransferase, alanine aminotransferase), liver histology and myeloperoxidase, and macrophage inflammatory protein-2 mRNA and cytokine-induced neutrophil chemoattractant mRNA in liver tissue, and animal survival at 3 days. Statistical analysis included Student's t test and analysis of variance when indicated. RESULTS: Significant improvement in liver function and histology was noted in the treated group. Survival was also improved, although it is not known whether liver failure was the most proximate cause of lethality. Infiltration of neutrophils, measured by tissue myeloperoxidase, was significantly decreased in livers of treated animals. No significant changes were noted in fluid requirements. The small molecule selectin inhibitor group showed a down-regulating effect on liver macrophage inflammatory protein-2 and cytokine-induced neutrophil chemoattractant mRNA expression associated with less accumulation of neutrophils in the liver. CONCLUSION: This study supports the role that selectins play in the pathogenesis of hemorrhagic shock. The mechanism of protection seen after multiple selectin blockade (TBC-1269) centered, in part, around the infiltration of liver neutrophils, probably dependent on the induction of macrophage inflammatory protein-2 and cytokine-induced neutrophil chemoattractant mRNA expression in liver tissue.

Analysis of Variance↗

Upregulation of lung chemokines associated with hemorrhage is reversed with a small molecule multiple selectin inhibitor.

BACKGROUND: Hemorrhage can modify the leukocyte-endothelial cell response leading to tissue injury. The selectin family of adhesion molecules and chemokines mediate the leukocyte-endothelial cell interaction, resulting in neutrophil sequestration and activation. This work studies whether a small molecule inhibitor of selectins can ameliorate the effect of hemorrhage on chemokine expression and neutrophil infiltration in the lung. We also aimed to assess the regulatory effect of this small molecule inhibitor of selectins in the lung functional and structural response of animals subjected to hemorrhagic shock. STUDY DESIGN: We subjected 36 Sprague-Dawley rats to uncontrolled hemorrhagic shock for a period of 150 minutes. Three groups of animals were included (n = 12 per group)-the sham, control, and treated groups, with the latter receiving a small molecule selectin inhibitor (TBC-1269) at 25 mg/kg, which was given after tail artery transection. The following measurements were evaluated: fluid requirements during resuscitation for 150 minutes; PO2/FIO2 ratio, lung water, and lung histology, lung myeloperoxidase and lung macrophage inflammatory protein-2 (MIP-2) mRNA and cytokine induced neutrophil chemoattractant mRNA at 6 hours. Statistical analysis included Student's t-test and ANOVA. RESULTS: There was significant improvement in lung function as expressed by PO2/FIO2 ratio and wet to dry lung water ratio in the treated group. There were no significant changes in fluid requirements between the three groups. Neutrophil infiltration, measured by tissue myeloperoxidase, was significantly (p < 0.05) decreased in the lungs of the treated animals. Lung histology was considerably improved in the treated group. The small molecule selectin inhibitor had a profound downregulating effect on macrophage inflammatory protein-2 and cytokine-induced neutrophil chemoattractant as expressed in lung tissue. CONCLUSIONS: Our study confirms the key role that selectins play in the pathogenesis of hemorrhagic shock. The multiple selectin blockade allowed for better function and structure of the lung. The mechanism of protection may be secondary to the downregulation of chemokine expression and neutrophil infiltration.

Animals↗

Dual blockade of P-selectin and beta2-integrin in the liver inflammatory response after uncontrolled hemorrhagic shock.

BACKGROUND: Neutrophil infiltration is a characteristic feature of the hepatic injury associated with prolonged hypotension. Previous work has already stressed the important contribution of neutrophil-endothelial cell interactions in the organ injury seen after hemorrhagic shock. Single-blockade strategies using monoclonal antibodies (MAbs) against either selectin or integrin receptors have been demonstrated to be effective in limiting the tissue inflammatory response observed in this clinical disorder. One unexplored topic is the additive effect(s) and the potential antiinflammatory properties of the combined blocking of P-selectin plus beta2-integrin in the liver inflammatory response after uncontrolled hemorrhagic shock in rats. STUDY DESIGN: Sprague-Dawley rats (n = 64) weighing 250-300 g were included in a three-phase model of uncontrolled hemorrhagic shock. A prehospital phase consisted of 90 minutes of fluid resuscitation with lactated Ringer's solution to reach a mean arterial pressure (MAP) of 40 mmHg; a hospital phase consisted of 60 minutes of hemostasis and fluid resuscitation with lactated Ringer's solution to reach a MAP of 80 mmHg; and the third phase was 3 days of observation. All rats had 3 mL/100 g of blood volume shed during the initial 15 minutes. At 30 minutes, 75% tail amputation produced uncontrolled hemorrhagic shock. Four groups were randomized (n = 16 per group), and treatment at the beginning of resuscitation included normal saline (group 1); anti-P-selectin MAb, RMP-1 (group 2); anti-beta2-integrin MAb, WT.3 (group 3); or anti-P-selectin plus anti-beta2-integrin MAbs (group 4). The following indices were evaluated: fluid requirements for resuscitation, liver injury tests, liver tissue myeloperoxidase, and liver histology. RESULTS: Dual blockade of P-selectin and beta2-integrin significantly reduced fluid requirements for resuscitation (p < 0.05). We also observed a statistically significant improvement (p < 0.05) in tests demonstrating hepatic injury, myeloperoxidase in hepatic tissue, and histology studies. Survival was increased from 40% in controls to 60% with the dual-blockade treatment. CONCLUSIONS: These results indicate that dual-blockade strategies aimed at P-selectin and beta-integrin provided a protective effect in the liver inflammatory response after uncontrolled hemorrhagic shock in rats. Although dual blockade was more effective than either individual blockade alone, questions remain about the possible redundancy in the inflammatory adhesion pathways after this clinical condition.

Alanine Transaminase↗

P-selectin blockade is beneficial after uncontrolled hemorrhagic shock.

OBJECTIVES: The selectins play an important role in the neutrophil-mediated injury after hemorrhagic shock and resuscitation. The aim of this study was to investigate the effect of P-selectin blockade after HS and resuscitation. METHODS: Forty-eight Sprague-Dawley rats were subjected to controlled combined with uncontrolled HS and resuscitation. Rats were divided into three groups (n = 16/group): (1) sham, no HS; (2) control, HS + resuscitation + drug vehicle; (3) treated, HS + anti-P-selectin monoclonal antibody. Transaminase levels to measure hepatocellular injury, liver myeloperoxidase to assess neutrophil infiltration, and histology were analyzed and compared between groups. Survival was followed for 3 days and was compared statistically. RESULTS: Survival significantly increased from 30% in the control group to 70% in the treated group. Hepatocellular and structural injury as well as neutrophil infiltration were significantly decreased in treated animals. CONCLUSION: Blockade of P-selectin resulted in decreased hepatocellular injury and increased survival in our model of uncontrolled HS. Selectins may be important therapeutic targets for blockade in the treatment of HS.

Animals↗

Tacrolimus (FK506) down-regulates free radical tissue levels, serum cytokines, and neutrophil infiltration after severe liver ischemia.

BACKGROUND: Liver ischemia and reperfusion injury is associated with activation of multiple inflammatory pathways, including free radicals, cytokines, and neutrophil-mediated tissue damage among others. Tacrolimus (FK506) has shown important regulatory effects on some inflammatory pathways, such as cytokines, neutrophils, and adhesion molecules. In this study, we explored a new potential protective mechanism for tacrolimus in the liver inflammatory response after ischemia and reperfusion, specifically its effect on liver tissue free radicals. METHODS: Total hepatic ischemia was produced in the rat for 90 min with an extracorporeal portosystemic shunt. Animals (n=96) were divided into four groups: group 1 comprised normal rats for reference values; group 2 comprised sham operated rats; in group 3, ischemic control rats received only the vehicle; and the experimental treatment group, group 4, received tacrolimus at a dose of 0.3 mg/kg, 4 hr before ischemia. Animal survival was followed up to 7 days. Liver function tests were performed and liver tissue free radicals and myeloperoxidase, serum cytokines (interleukin 1, tumor necrosis factor-alpha), and liver histology were measured 4 hr after reperfusion. RESULTS: Seven-day survival was significantly improved from only 20% in the control group to 55% in the tacrolimus group (P<0.01). Liver function tests, histology, and myeloperoxidase tissue values were significantly improved (P<0.05) with tacrolimus pretreatment. Furthermore, a significant (P<0.05) down-regulation of serum cytokines and liver tissue free radicals was observed. CONCLUSIONS: These data indicate a new and different protective mechanism for FK506 in regard to its ability to down-regulate free radical levels in livers subjected to severe ischemia and reperfusion. Tacrolimus, also confirmed to be a potent suppressor of the cytokine response, specifically interleukin 1 and tumor necrosis, decreased neutrophil tissue migration as well.

Animals↗

Sulfo-Lewis(x) diminishes neutrophil infiltration and free radicals with minimal effect on serum cytokines after liver ischemia and reperfusion.

BACKGROUND: Cell adhesion plays a central role in the pathogenesis of neutrophil-induced hepatic injury after ischemia and reperfusion. Sialyl Lewis(x) binds to selectins mediating neutrophil adherence to endothelium, thereby facilitating subsequent migration and tissue damage. AIM: We studied the effect of a novel sulfo-derivative of sialyl Lewis(x), GM-1998, on the liver inflammatory response after ischemia and reperfusion. Specifically, we evaluated its impact on three key inflammatory mediators: neutrophil migration, free radicals, and serum cytokines. MATERIAL AND METHODS: Rats were subjected to total hepatic ischemia for 90 min using an extracorporeal portosystemic shunt to avoid splanchnic congestion. GM-1998 was given at a total dose of 20 mg/kg both prior to and after reperfusion. Liver function tests, liver tissue free radicals, and myeloperoxidase (MPO), serum cytokines (IL-1, TNF-alpha), and liver histology were analyzed 4 hr after reperfusion. Additionally, survival was followed for up to 7 days. RESULTS: Seven-day survival significantly increased from 20% in the control group to 65% in the sulfo-Lewis(x) treated group. Liver function tests and histological damage scores were improved in comparison to controls. We observed significant downregulation of free radicals and neutrophil migration. This compound did not significantly affect serum cytokine levels. CONCLUSIONS: GM-1998 showed a protective effect in an in vivo model of severe liver ischemia and reperfusion by decreasing tissue free radical levels and selectin-mediated neutrophil migration. This protective effect was also reflected in improved liver function tests and histological response leading to better survival. We confirmed the beneficial effect of neutrophil blockade as a key target to prevent damage after the reperfusion phenomenon by using a glycomimetic sulfo-Lewis(x).

Animals↗

Sialyl Lewis(x) analog improves liver function by decreasing neutrophil migration after hemorrhagic shock.

BACKGROUND: Little is known about the changes in the hepatic microcirculation and the leukocyte-endothelial adhesion processes during the early reperfusion period after resuscitation in hemorrhagic shock. P-selectin and its natural ligand Sialyl Lewis(x) (SLe(x)) are involved in the early stages of reperfusion events leading to neutrophil migration. Therefore, the aim of this study was to investigate the effect of the administration of CY-1503 [corrected], a synthetic SLe(x) analog, in the liver inflammatory response and neutrophil migration after hemorrhagic shock. MATERIALS AND METHODS: Rats, each weighing 275 to 300 grams, were subjected to 60 minutes of pressure controlled hemorrhagic shock. After this period, animals were resuscitated according to the following protocol: shed blood was reinfused to equal 50% of the total volume bled, and the other 50% was replaced with 3x volume of Ringer's lactated solution. Animals were divided into sham and two study groups to receive vehicle (controls) and CY-1503 [corrected] (10 mg/kg intravenously) diluted in 1 mL of normal saline 45 minutes after initiating hemorrhagic shock. The following parameters were analyzed: 7-day survival, liver injury tests, liver tissue myeloperoxidase as an index of neutrophil infiltration, and liver histology. RESULTS: Survival was significantly increased from 48% in the controls to 90% in the CY-1503 [corrected] treated group. Animals treated with the SLe(x) analog showed significantly better mean arterial blood pressure after 15 minutes after resuscitation. Also, the treated group showed a marked decrease in liver enzymes levels at 5 minutes and 4 hours after reperfusion. Neutrophil migration was significantly ameliorated as reflected by decreased myeloperoxidase levels in the SLe(x) analog treated group. Furthermore, we observed improved histologic damage scores in the treated group when compared with controls. CONCLUSIONS: The SLe(x) analog, CY-1503 [corrected], had a protective effect in ischemic livers by decreasing neutrophil migration after hemorrhagic shock and resuscitation. This protective effect also resulted in improved survival and mean arterial blood pressure after resuscitation.

Animals↗

Time dependence of Na-nitroprusside administration in the prevention of neutrophil infiltration in the rat ischemic kidney.

The aim of this study was to determine the ideal time of administration of Na-nitroprusside to prevent neutrophil infiltration in ischemically damaged kidneys. Sprague-Dawley rats were subjected to 75 min of renal warm ischemia and contralateral nephrectomy. The animals were divided into 7 groups: the ischemic control (IC), which received normal saline, the sham group without warm ischemia and the experimental groups, which received intravenous Na-nitroprusside (NP) (5 mg/kg) at 75, 30, 15, and 5 min prior to reperfusion. Another experimental group was given verapamil (V) (5 mg/kg) as a NO-independent vasodilator 5 min prior to reperfusion. The final evaluation included survival at seven days, serum creatinine (SCr) and blood urea nitrogen (BUN) daily for 3 days, and neutrophil infiltration determined by the presence of myeloperoxidase (MPO) in renal tissue at 2 hr after reperfusion. Histological damage was assessed at 24 hr. There were significant improvements in all parameters when the Na-NP was administered at 75, 30, and 15 min prior to reperfusion when compared with the control group (p < 0.05). There were no differences either in survival or renal function when the 5 min group was compared with the IC or V groups. It is concluded then, that Na-NP can be administered as late as 15 min before reperfusion and still have a protective effect. It appears that the mechanism of protection of Na-NP is due to blocking of one of the steps of the interaction between leukocytes and endothelium--migration. Furthermore, the verapamil (a NO-independent vasodilator) and Na-NP5 (a NO-dependent vasodilator) groups did not show a beneficial effect in these severely ischemically damaged kidneys, which might be one more reason to believe that Na-NP could be interacting at the level of leukocyte-endothelial cell interaction.

Animals↗

Mechanism of protection of verapamil by preventing neutrophil infiltration in the ischemic rat kidney.

In this study, we tested if the mechanism of protection of a calcium channel blocker, Verapamil (VER), was due to modulation of neutrophil infiltration after ischemia/reperfusion injury, in a rat renal ischemic model. Forty-four Sprague-Dawley rats were subjected to 75 min of warm ischemia and immediate contralateral nephrectomy. The animals were divided into two groups: the ischemic control (IC) group, which received normal saline, and the experimental group that received VER 1.25 mg/kg. The drug was administrated intravenously after ligation of the renal pedicle, before reperfusion. Survival was followed for 7 days. Laboratory tests included renal function tests, with serum creatinine (SCr) and blood urea nitrogen (BUN), light histology and neutrophil infiltration, measured by the myeloperoxidase test in renal tissue. Better survival rate was observed in the VER group (85% at 7 days vs control 50%) (P = 0.08). SCr and BUN at 48 and 72 hr showed a statistical significant difference between the two groups (VER lower than IC P < 0.05). Histological damage was significantly less in the VER group (P < 0.05). Neutrophil infiltration was significantly decreased in the VER group when compared to the IC group (P < 0.05). We concluded then, that VER had a downregulating effect on neutrophil infiltration and this might be an important mechanism of protection during the development of renal ischemic damage.

Animals↗

21-Aminosteroids block neutrophil infiltration and provide liver protection independent of NO2-/NO3- levels.

21-Aminosteroids are antioxidant compounds that prevent iron-dependent lipid peroxidation and improve cell viability. In this work we attempt to define the role of 21-aminosteroids in liver ischemia and reperfusion and assess their possible mode of action, specifically their effect on neutrophil infiltration and nitrite/nitrate levels. Total liver ischemia for 90 min was produced in the rat with the use of a portosystemic shunt. Three groups of animals were studied. One group received the 21-aminosteroid U-74389G (10 mg/ kg) divided into two equal doses 10 min prior to ischemia (7 mg/kg) and 10 min before reperfusion (3 mg/ kg). The two other groups included the sham and the control animals. We studied survival at 7 days and serum liver enzymes, liver myeloperoxidase, plasma nitrites, nitrates, and liver histology at 6 hr postreperfusion. Animal survival improved from 13% in the ischemic control to 52% in the lazaroid treated group (P < 0.05). We observed significant improvements in liver function tests, liver myeloperoxidase levels, as well as in the liver histology (P < 0.05). We could not find statistical difference in plasma nitrite/nitrate (P > 0.1). The 21-aminosteroids significantly improved animal survival after total liver ischemia, through a mechanism that includes blocking neutrophil infiltration which is independent from nitrite/nitrate levels.

Animals↗

Role of sialyl Lewis(x) in total hepatic ischemia and reperfusion.

BACKGROUND: Neutrophil adhesion and migration is associated with hepatic ischemia and reperfusion. The role of a Sialyl Lewis(x) (SLe)(x) oligosaccharide, a ligand for selections, was studied in hepatic ischemia and reperfusion injury. STUDY DESIGN: Total hepatic ischemia was produced in rats for 90 minutes using an extracorporeal portosystemic shunt. To assess the role of SLe(x) in hepatic ischemia and reperfusion injury, 25 mg/kg of an SLe(x) analog, CY-1503, was given five minutes before reperfusion or at reperfusion. Biochemical tests of hepatic injury, myeloperoxidase activity in hepatic tissue, and histologic studies, including neutrophil infiltration determined by the naphthol esterase technique, were analyzed six hours after reperfusion. RESULTS: Significantly improved protection in biochemical hepatic injury tests (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase) was noted between the ischemic and the SLe(x) treated groups. Myeloperoxidase activity and polymorphonuclear cell infiltration in hepatic tissue were decreased in the SLe(x) groups. Histologic protection from hepatic damage was observed in the treated groups. CONCLUSIONS: The SLe(x) oligosaccharide analog, CY-1503, had an important protective role in hepatic ischemia and reperfusion injury. Modulation of SLe(x) in the neutrophil decreased the adhesion of polymorphonuclear cells and their subsequent migration after hepatic ischemia and reperfusion.

Animals↗