HIV-1 infection modulates IL-24 expression which contributes to cell apoptosis in vitro.

Although interleukin-24 (IL-24) has been extensively explored in the immunopathologies of autoimmune diseases, neoplasms, and infections, its role in HIV-1 infection has not been thoroughly elucidated to date. Therefore, the objective of this study was to evaluate the gene and protein expressions of IL-24 at the initial moments of HIV infection in PBMCs. Due to the pro-apoptotic role of IL-24, we evaluated the protein expression of caspase-3, as well as Annexin V/Propidium Iodide flow cytometry and phosphorylation of ERK, which may induce an apoptotic signal block when phosphorylated. The results of this study demonstrated that HIV-1 infection had an impact on the gene and protein expressions of IL-24 and ERK. Annexin V/Propidium Iodide assay demonstrated decrease in the mechanisms of apoptosis in infected cells after incubation of IL-24 neutralizing antibody. Studies on how HIV-1 regulates IL-24 expression may play a role in characterizing viral persistence mechanisms and designing antiretroviral strategies.

Is serum amyloid A an endogenous TLR4 agonist?

Serum amyloid A (SAA), a classical acute-phase protein, is produced predominantly by hepatocytes in response to injury, infection, and inflammation. It has been shown that SAA primes leukocytes and induces the expression and release of proinflammatory cytokines. Here, we report that SAA induces NO production by murine peritoneal macrophages. Using specific inhibitors, we showed that NO production was dependent on inducible NO synthase thorough the activation of ERK1/2 and p38 MAPKs. Moreover, SAA activity was decreased after proteolysis but not with polymyxin B, a lipid A antagonist. Finally, we found that NO production was dependent on functional TLR4, a receptor complex associated with innate immunity. Macrophages from C3H/HeJ and C57BL/10ScCr mice lacking a functional TLR4 did not respond to SAA stimulation. In conclusion, our study makes a novel observation that SAA might be an endogenous agonist for the TLR4 complex on macrophages. The contribution of this finding in amplifying innate immunity during the inflammatory process is discussed.

S-nitrosothiols and H2S donors: Potential chemo-therapeutic agents in cancer.

Nitric Oxide (NO) and Hydrogen Sulfide (H2S) are components of an "interactome", which is defined as a redox system involving the interactions of RSS, RNS and ROS. Chemical interaction by these species is common and is characterized by one and two electron oxidation, nitrosylation, nitration and sulfuration/polysulfidation reactions. NO and H2S are gases that penetrate cell membranes, are synthesized by specific enzymes, are ubiquitous, regulate protein activities through post-translational modifications and participate in cell signaling. The two molecules at high concentrations compared to physiological concentrations may result in cellular damage particularly through their interaction with other reactive species. NO and H2S can interact with each other and form a variety of molecular species which may have constructive or destructive behavior depending on the cell type, the cellular environment (ex. oxygen tension, pH, redox state), where the products are produced and in what concentrations. Cross talk exists between NO and H2S, whereby they can influence the generation and signaling behavior of each other. Given the above mentioned properties of NO and H2S and studies in cancer cells and animal models employing NO and H2S donors that generate higher than physiological concentrations of NO and H2S and are effective in killing cancer cells but not normal cells, lend credence to the possibility of the utility of these donors in an approach to the treatment of cancer.

Conformational study of the electronic interactions and nitric oxide release potential of new S­nitrosothiols esters derivatives of ibuprofen, naproxen and phenyl acids substituted (SNO-ESTERS): Synthesis, infrared spectroscopy analysis and theoretical calculations.

The conformational study on the new S­nitrosothiols esters (SNO-ESTERS): para-substituted (X = H, OMe, Cl and NO2) S­nitrosothiol derivatives 2­methyl­2­(sulfanyl)propyl phenylacetates (R1), 2­(4­isobutylphenyl)propanoate (ibuprofen, R2), and 2­(4­isobutylphenyl)propanoate of 2­methyl­2­(nitrososulfanyl)propyl (naproxen, R3) was performed using infrared spectroscopy (IR) in solvents with increasing polarity (CCl4, CH3Cl, and CH3CN), and theoretical calculations, to determine the preferential conformer and the potential of these compounds to release nitric oxide (NO). S­Nitrosothiols were synthesized by esterification reactions, using chlorides of the corresponding carboxylic acids, with good yields (~60%). IR results showed that these compounds presented only one conformation, and the experimental data were supported by the theoretical results obtained by density functional theory (DFT) calculations using the 6311+G (2df, 2p) basis set. The calculations revealed that all S­nitrosothiols presented one preferential anticlinal (ac) geometric conformation, which agrees with the data obtained experimentally in CCl4. These conformers are stabilized by intramolecular hydrogen bonds. Examination of the geometry with regard to the RSNO group revealed that these compounds are preferentially in the trans (anti) conformation. The calculation of the orbital interactions using the Natural Bond Orbital (NBO) method showed that the nO(NO) → σ(SN)∗ hyper-conjugative interaction increases the SN bond length. The strong nS → π(NO)∗ interaction and electronic delocalization induces a partial π character to the SN bond. The weak σSN bond indicates strong delocalization of the electron pair in O (NO) by the nO(NO) → σ(SN)∗ interaction, thereby increasing the capacity of NO release from SNO-ESTERS.

The expression of endothelial and inducible nitric oxide synthase and apoptosis in intestinal ischemia and reperfusion injury under the action of ischemic preconditioning and pentoxifylline.

PURPOSE: To investigate the expression of nitric oxide synthase (NOS) and apoptosis associated with ischemic preconditioning (IPC) and pentoxifylline (PTX) in intestinal ischemia (I) and reperfusion (R) injury. METHODS: Thirty male rats were assigned to 5 groups: (CG), no clamping of the superior mesenteric artery (90 minutes); (IR-SS) saline + ischemia (30 minutes) + reperfusion (60 minutes); (IR-PTX) PTX + ischemia (30 minutes) + reperfusion (60 minutes); (IPC-IR-SS) 5 minutes of ischemia + 5 minutes of reperfusion (IPC) + saline + I(30 minutes)+R(60 minutes); and (IPC-IR-PTX) IPC + PTX + I(30 minutes)+ R(60 minutes). RESULTS: The application of IPC and PTX showed a significantly lower immunohistochemistry reaction for active caspase-3 (P<0.05) compared to IR+SS. The number of cells immunoreactive to BCL-2 was higher in the IR-PTX group (P>0.05). The NOS-2 expression (qRTPCR) in the IR-PTX group (P<0.05) was higher than the values for the IPC+IR-SS and IPC-IR-PTX groups. The NOS-3 expression was significantly upper in the IPC-IR-PTX group than in the CG (P<0.05), the IR-SS (P<0.05) and the IR-PTX (P<0.05) groups. CONCLUSIONS: The BCL-2 and active caspase-3 showed beneficial effects on PTX and IPC. The expression of NOS-2 and NOS-3 in the IPC and IPC-PTX groups showed no synergistic effect.

The role of ischemic preconditioning and pentoxifylline in intestinal ischemia/reperfusion injury of rats.

PURPOSE:: To investigate the role of ischemic preconditioning (IPC) and pentoxifylline (PTX) in intestinal mucosa ischemia/reperfusion injury (IR). METHODS:: Thirty rats were assigned to 5 groups (N=6): (CG): no clamping of the superior mesenteric artery (90 min.); (IR-SS): saline + ischemia (30 min.) + reperfusion (60 min.); (IR-PTX): PTX + ischemia (30min.) + reperfusion (60 min.); (IPC-IR-SS): 5 min. of ischemia + 5 minutes of reperfusion (IPC) + saline + ischemia (30 min.) + reperfusion (60 min.); (IPC-IR-PTX ): 5 min. of ischemia + 5 min. of reperfusion (IPC) + PTX + 30 min. of I + 60 minutes of R. RESULTS:: The IR-PTX, IPC-IR-SS and IPC-IR-PTX groups had significantly lower scores of mucosa damage than the IR-SS group. IR-PTX group showed higher scores than the IPC-IR-PTX group, in accordance with the hypothesis of a favorable effect of IPC alone or in association with PTX. Additionally, IPC-IR-SS had a higher damage score than the IPC-IR-PTX. The villi height and crypt depth were similar in all groups. The villi height in the IR-SS was significantly lower. CONCLUSION:: Ischemic preconditioning or pentoxifylline alone protect the intestinal mucosa from ischemia/reperfusion injury. However, they do not have a synergistic effect when applied together.

Inducible Nitric Oxide Synthase in the Carcinogenesis of Gastrointestinal Cancers.

SIGNIFICANCE: Gastrointestinal (GI) cancer taken together constitutes one of the most common cancers worldwide with a broad range of etiological mechanisms. In this review, we have examined the impact of nitric oxide (NO) on the etiology of colon, colorectal, gastric, esophageal, and liver cancers. Recent Advances: Despite differences in etiology, initiation, and progression, chronic inflammation has been shown to be a common element within these cancers showing interactions of numerous pathways. NO generated at the inflammatory site contributes to the initiation and progression of disease. The amount of NO generated, time, and site vary and are an important determinant of the biological effects initiated. Among the nitric oxide synthase enzymes, the inducible isoform has the most diverse range, participating in numerous carcinogenic processes. There is emerging evidence showing that inducible nitric oxide synthase (NOS2) plays a central role in the process of tumor initiation and/or development. CRITICAL ISSUES: Redox inflammation through NOS2 and cyclooxygenase-2 participates in driving the mechanisms of initiation and progression in GI cancers. FUTURE DIRECTIONS: Understanding the underlying mechanism involved in NOS2 activation can provide new insights into important prevention and treatment strategies. Antioxid. Redox Signal. 26, 1059-1077.

Heparin modulates the expression of genes encoding pro and anti-apoptotic proteins in endothelial cells exposed to intestinal ischemia and reperfusion in rats.

PURPOSE: To investigate if expression of genes encoding pro and anti-apoptotic proteins in the rat enteric endothelial cells stimulated by intestinal ischemia followed by reperfusion (IR) can be modified by treatment with heparin (HP). METHODS: Eighteen adult Wistar rats were divided in three groups: sham group submitted to laparotomy only (SG), ischemia followed by reperfusion group (IRG); ischemia followed by reperfusion plus pretreatment with HP 100 mg.kg-1 (IRG+HP). Ischemia was performed by clamping of the superior mesenteric artery. After 60 min of ischemia, metal clamps were removed for reperfusion for 120 min. Gene expression of encoding pro (Casp1, Casp6, Casp3, Cflar, Fas and Pgl) and anti-apoptotic (Bcl2, Bcl2l1 and Naip2) proteins in rat enteric endothelial cells was evaluated by PCR microarray method. RESULTS: Compared to rat endothelial cells of SG, the expression of pro-apoptotic genes was up-regulated in IRG while anti-apoptotic genes were down-regulated. In contrast, the expression of anti-apoptotic genes in IRG+HP was up-regulated while pro-apoptotic genes was down-regulated compared to SG. CONCLUSION: The attenuation by heparin of intestinal ischemia-reperfusion previously demonstrated in rodents could be related with ability of this drug to stimulate and reduce gene expression of encoding anti and pro-apoptotic proteins, respectively.

Ischemic preconditioning and the gene expression of enteric endothelial cell biology of rats submitted to intestinal ischemia and reperfusion.

PURPOSE: To investigate the effects of ischemic preconditioning (IPC) on the expression of pro and anti-apoptotic genes in rat endothelial cells undergoing enteric ischemia (I) and reperfusion (R). METHODS: Thirty rats underwent clamping of the superior mesenteric vessels. Sham group (GS) laparotomy only; Ischemia (GI): intestinal ischemia (60 min); Ischemia and Reperfusion (GIR): ischemia (60 min) and reperfusion (120 min); Ischemia and intestinal ischemic preconditioning (GI + IPC) : 5 minutes of ischemia followed by 10 min of reperfusion before sustained ischemia (60 min) ischemia and reperfusion and IPC (GIR + IPC): 5 min ischemia followed by 10 min of reperfusion before sustained ischemia (60min) and reperfusion (120 min). Rat Endothelial Cell Biology (PCR array) to determine the expression of genes related to endothelial cell biology. RESULTS: Gene expression of pro-apoptotic markers (Casp1, Casp6, Cflar, Fas, and Pgl) was down regulated in GI+IPC and in GIR + IPC. In contrast, the expression of anti-apoptotic genes (Bcl2 and Naip2), was up-regulated in GI + IPC and in GIR + IPC. CONCLUSION: Ischemic preconditioning may protect against cell death caused by ischemia and reperfusion.

Nitrosative/oxidative stress conditions regulate thioredoxin-interacting protein (TXNIP) expression and thioredoxin-1 (TRX-1) nuclear localization.

Thioredoxin (TRX-1) is a multifunctional protein that controls the redox status of other proteins. TRX-1 can be found in the extracellular milieu, cytoplasm and nucleus, and it has distinct functions in each environment. Previously, we studied the intracellular localization of TRX-1 and its relationship with the activation of the p21Ras-ERK1/2 MAP Kinases signaling pathway. In situations where this pathway was activated by stress conditions evoked by a nitrosothiol, S-nitroso-N-acetylpenicillamine (SNAP), TRX-1 accumulated in the nuclear compartment due to nitrosylation of p21Ras and activation of downstream ERK1/2 MAP kinases. Presently, we demonstrate that ERK1/2 MAP Kinases activation and spatial distribution within cells trigger TRX-1 nuclear translocation through down-regulation of the physiological inhibitor of TRX-1, Thioredoxin Interacting Protein (TXNIP). Once activated by the oxidants, SNAP and H2O2, the ERK1/2 MAP kinases migrate to the nucleus. This is correlated with down-regulation of TXNIP. In the presence of the MEK inhibitors (PD98059 or UO126), or in cells transfected with the Protein Enriched in Astrocytes (PEA-15), a cytoplasmic anchor of ERK1/2 MAP kinases, TRX-1 nuclear migration and TXNIP down-regulation are no longer observed in cells exposed to oxidants. On the other hand, over-expression of TXNIP abolishes nuclear migration of TRX-1 under nitrosative/oxidative stress conditions, whereas gene silencing of TXNIP facilitates nuclear migration even in the absence of stress conditions. Studies based on the TXNIP promoter support this regulation. In conclusion, changes in TRX-1 compartmentalization under nitrosative/oxidative stress conditions are dependent on the expression levels of TXNIP, which are regulated by cellular compartmentalization and activation of the ERK1/2 MAP kinases.

Low concentrations of hydrogen peroxide or nitrite induced of Paracoccidioides brasiliensis cell proliferation in a Ras-dependent manner.

Paracoccidioides brasiliensis, a causative agent of paracoccidioidomycosis (PCM), should be able to adapt to dramatic environmental changes inside the infected host after inhalation of air-borne conidia and transition to pathogenic yeasts. Proteins with antioxidant functions may protect fungal cells against reactive oxygen (ROS) and nitrogen (RNS) species generated by phagocytic cells, thus acting as potential virulence factors. Ras GTPases are involved in stress responses, cell morphology, and differentiation in a range of organisms. Ras, in its activated form, interacts with effector proteins and can initiate a kinase cascade. In lower eukaryotes, Byr2 kinase represents a Ras target. The present study investigated the role of Ras in P. brasiliensis after in vitro stimulus with ROS or RNS. We have demonstrated that low concentrations of H2O2 (0.1 mM) or NO2 (0.1-0.25 µM) stimulated P. brasiliensis yeast cell proliferation and that was not observed when yeast cells were pre-incubated with farnesyltransferase inhibitor. We constructed an expression plasmid containing the Byr2 Ras-binding domain (RBD) fused with GST (RBD-Byr2-GST) to detect the Ras active form. After stimulation with low concentrations of H2O2 or NO2, the Ras active form was observed in fungal extracts. Besides, NO2 induced a rapid increase in S-nitrosylated Ras levels. This alternative posttranslational modification of Ras, probably in residue Cys123, would lead to an exchange of GDP for GTP and consequent GTPase activation in P. brasiliensis. In conclusion, low concentrations of H2O2 or NO2 stimulated P. brasiliensis proliferation through Ras activation.

L-arginine in the ischemic phase protects against liver ischemia-reperfusion injury.

PURPOSE: To investigate the effects of intravenous L-arginine (LG) infusion on liver morphology, function and proinflammatory response of cytokines during the early phase of ischemia-reperfusion injury (IRI). METHODS: Thirty rabbits were subjected to 60 minutes of hepatic ischemia and 120 minutes of reperfusion. An intravenous injection of saline or L-arginine was administered five minutes before the ischemia and five minutes before initiating the reperfusion and at the 55th and 115th minutes after the ischemia. Samples were collected for histological analysis of the liver and measurements of the serum AST, ALT and LDH and the cytokines IL-6 and TNF-alpha. RESULTS: It was observed a significant reduction of sinusoidal congestion, cytoplasmic vacuolization, infiltration of polymorphonuclear leukocyte, nuclear pyknosis, necrosis and steatosis in liver tissue, as well as AST, ALT and LDH after injection of LG in the ischemia (p <0.001). Lower levels of IL-6 and TNF-alpha were associated with LG infusion during ischemia. Higher levels these proteins were observed in animals receiving LG during reperfusion. CONCLUSION: L-arginine protects the liver against ischemia/reperfusion injury, mainly when is administered during the ischemic phase.

The role of ischemic preconditioning and pentoxifylline in intestinal ischemia/reperfusion injury of rats

Abstract Purpose: To investigate the role of ischemic preconditioning (IPC) and pentoxifylline (PTX) in intestinal mucosa ischemia/reperfusion injury (IR). Methods: Thirty rats were assigned to 5 groups (N=6): (CG): no clamping of the superior mesenteric artery (90 min.); (IR-SS): saline + ischemia (30 min.) + reperfusion (60 min.); (IR-PTX): PTX + ischemia (30min.) + reperfusion (60 min.); (IPC-IR-SS): 5 min. of ischemia + 5 minutes of reperfusion (IPC) + saline + ischemia (30 min.) + reperfusion (60 min.); (IPC-IR-PTX ): 5 min. of ischemia + 5 min. of reperfusion (IPC) + PTX + 30 min. of I + 60 minutes of R. Results: The IR-PTX, IPC-IR-SS and IPC-IR-PTX groups had significantly lower scores of mucosa damage than the IR-SS group. IR-PTX group showed higher scores than the IPC-IR-PTX group, in accordance with the hypothesis of a favorable effect of IPC alone or in association with PTX. Additionally, IPC-IR-SS had a higher damage score than the IPC-IR-PTX. The villi height and crypt depth were similar in all groups. The villi height in the IR-SS was significantly lower. Conclusion: Ischemic preconditioning or pentoxifylline alone protect the intestinal mucosa from ischemia/reperfusion injury. However, they do not have a synergistic effect when applied together.

The expression of endothelial and inducible nitric oxide synthase and apoptosis in intestinal ischemia and reperfusion injury under the action of ischemic preconditioning and pentoxifylline

Abstract Purpose: To investigate the expression of nitric oxide synthase (NOS) and apoptosis associated with ischemic preconditioning (IPC) and pentoxifylline (PTX) in intestinal ischemia (I) and reperfusion (R) injury. Methods: Thirty male rats were assigned to 5 groups: (CG), no clamping of the superior mesenteric artery (90 minutes); (IR-SS) saline + ischemia (30 minutes) + reperfusion (60 minutes); (IR-PTX) PTX + ischemia (30 minutes) + reperfusion (60 minutes); (IPC-IR-SS) 5 minutes of ischemia + 5 minutes of reperfusion (IPC) + saline + I(30 minutes)+R(60 minutes); and (IPC-IR-PTX) IPC + PTX + I(30 minutes)+ R(60 minutes). Results: The application of IPC and PTX showed a significantly lower immunohistochemistry reaction for active caspase-3 (P<0.05) compared to IR+SS. The number of cells immunoreactive to BCL-2 was higher in the IR-PTX group (P>0.05). The NOS-2 expression (qRTPCR) in the IR-PTX group (P<0.05) was higher than the values for the IPC+IR-SS and IPC-IR-PTX groups. The NOS-3 expression was significantly upper in the IPC-IR-PTX group than in the CG (P<0.05), the IR-SS (P<0.05) and the IR-PTX (P<0.05) groups. Conclusions: The BCL-2 and active caspase-3 showed beneficial effects on PTX and IPC. The expression of NOS-2 and NOS-3 in the IPC and IPC-PTX groups showed no synergistic effect.

Heparin modulates the expression of genes encoding pro and anti-apoptotic proteins in endothelial cells exposed to intestinal ischemia and reperfusion in rats

PURPOSE: To investigate if expression of genes encoding pro and anti-apoptotic proteins in the rat enteric endothelial cells stimulated by intestinal ischemia followed by reperfusion (IR) can be modified by treatment with heparin (HP). METHODS: Eighteen adult Wistar rats were divided in three groups: sham group submitted to laparotomy only (SG), ischemia followed by reperfusion group (IRG); ischemia followed by reperfusion plus pretreatment with HP 100 mg.kg-1 (IRG+HP). Ischemia was performed by clamping of the superior mesenteric artery. After 60 min of ischemia, metal clamps were removed for reperfusion for 120 min. Gene expression of encoding pro (Casp1, Casp6, Casp3, Cflar, Fas and Pgl) and anti-apoptotic (Bcl2, Bcl2l1 and Naip2) proteins in rat enteric endothelial cells was evaluated by PCR microarray method. RESULTS: Compared to rat endothelial cells of SG, the expression of pro-apoptotic genes was up-regulated in IRG while anti-apoptotic genes were down-regulated. In contrast, the expression of anti-apoptotic genes in IRG+HP was up-regulated while pro-apoptotic genes was down-regulated compared to SG. CONCLUSION: The attenuation by heparin of intestinal ischemia-reperfusion previously demonstrated in rodents could be related with ability of this drug to stimulate and reduce gene expression of encoding anti and pro-apoptotic proteins, respectively. .

Ischemic preconditioning and the gene expression of enteric endothelial cell biology of rats submitted to intestinal ischemia and reperfusion

PURPOSE: To investigate the effects of ischemic preconditioning (IPC) on the expression of pro and anti-apoptotic genes in rat endothelial cells undergoing enteric ischemia (I) and reperfusion (R). METHODS: Thirty rats underwent clamping of the superior mesenteric vessels. Sham group (GS) laparotomy only; Ischemia (GI): intestinal ischemia (60 min); Ischemia and Reperfusion (GIR): ischemia (60 min) and reperfusion (120 min); Ischemia and intestinal ischemic preconditioning (GI + IPC) : 5 minutes of ischemia followed by 10 min of reperfusion before sustained ischemia (60 min) ischemia and reperfusion and IPC (GIR + IPC): 5 min ischemia followed by 10 min of reperfusion before sustained ischemia (60min) and reperfusion (120 min). Rat Endothelial Cell Biology (PCR array) to determine the expression of genes related to endothelial cell biology. RESULTS: Gene expression of pro-apoptotic markers (Casp1, Casp6, Cflar, Fas, and Pgl) was down regulated in GI+IPC and in GIR + IPC. In contrast, the expression of anti-apoptotic genes (Bcl2 and Naip2), was up-regulated in GI + IPC and in GIR + IPC. CONCLUSION: Ischemic preconditioning may protect against cell death caused by ischemia and reperfusion.

L-arginine in the ischemic phase protects against liver ischemia-reperfusion injury / A L-arginina durante a fase isquêmica protege o fígado das lesões de isquemia e reperfusão

PURPOSE: To investigate the effects of intravenous L-arginine (LG) infusion on liver morphology, function and proinflammatory response of cytokines during the early phase of ischemia-reperfusion injury (IRI). METHODS: Thirty rabbits were subjected to 60 minutes of hepatic ischemia and 120 minutes of reperfusion. An intravenous injection of saline or L-arginine was administered five minutes before the ischemia and five minutes before initiating the reperfusion and at the 55th and 115th minutes after the ischemia. Samples were collected for histological analysis of the liver and measurements of the serum AST, ALT and LDH and the cytokines IL-6 and TNF-alpha. RESULTS: It was observed a significant reduction of sinusoidal congestion, cytoplasmic vacuolization, infiltration of polymorphonuclear leukocyte, nuclear pyknosis, necrosis and steatosis in liver tissue, as well as AST, ALT and LDH after injection of LG in the ischemia (p <0.001). Lower levels of IL-6 and TNF-alpha were associated with LG infusion during ischemia. Higher levels these proteins were observed in animals receiving LG during reperfusion. CONCLUSION: L-arginine protects the liver against ischemia/reperfusion injury, mainly when is administered during the ischemic phase.

OBJETIVO: Investigar os efeitos da infusão endovenosa da L-arginina (LG) na morfologia, função e resposta de citocinas pró-inflamatórias do fígado durante a fase precoce da lesão de isquemia e reperfusão (IRI). MÉTODOS: Trinta coelhos foram submetidos a 60 minutos de isquemia hepática e 120 minutos de reperfusão. Foi administrada injecção intravenosa de solução salina ou L-arginina aos cinco minutos antes de iniciar a isquemia e cinco minutos antes de iniciar a reperfusão e aos 55 e 115 minutos após o início da isquemia. Realizou-se análise histológica do fígado e dosagens séricas de AST, ALT, LDH, citocinas IL-6 e TNF-alfa. RESULTADOS: Ocorreu redução significante da congestão sinusoidal, vacuolização citoplasmática, infiltração de leucócitos polimorfonucleares, picnose nuclear, necrose e esteatose no tecido hepático, assim como nos níveis de AST, ALT e LDH após a injeção da LG na isquemia (p<0,001). Níveis mais baixos de IL-6 e TNF-alfa foram associados com a infusão LG durante a isquemia. Níveis mais elevados dessas proteínas foram observados nos animais que receberam LG durante a reperfusão. CONCLUSÃO: A L-arginina protegeu o fígado contra a lesão de isquemia e reperfusão principalmente quando administrada durante a fase de isquemia.

Interaction of [3H]8-methoxypsoralen with cultured normal human epidermal melanocytes

FUNDAMENTOS - O tratamento normalmente usado para o vitiligo envolve a combinaçäo de 8-metoxipsoraleno (8-MOP) e radiaçäo ultravioleta A, conhecida como PUVA-terapia. Embora a estimulaçäo da proliferaçäo e diferenciaçäo de melanócitos possa explicar a eficiência da PUVA-terapia no tratamento do vitiligo, até a presente data, näo se demonstrou nenhuma interaçäo direta desse composto com melanócitos humanos normais em cultura. OBJETIVOS - Estudar a interaçäo de [3H]8-metoxipsoraleno com melanócitos humanos normais em cultura obtidos de indivíduos de cor branca e negra. MÉTODOS - Melanócitos humanos normais isolados de prepúcios de crianças e mantidos em meio MCDB-153 na ausência de soro, éster de forbol (PMA) e toxina da cólera, foram incubados com [3H]8-metoxipsoraleno para determinaçäo da ligaçäo específica a essas células. RESULTADOS - Melanócitos isolados de ambos os tipos de pele, mostraram ligaçäo com 8-MOP, embora uma maior porcentagem de ligaçäo tenha sido observada em melanócitos isolados de pessoas de cor negra. CONCLUSÖES - A capacidade proliferativa de melanócitos humanos normais varia de acordo com a cor racial. É possível que as diferenças observadas na ligaçäo do psoraleno, estejam relacionadas com diferenças quanto ao número de receptores de psoralenos entre melanócitos isolados de pele clara e escura