Methylene blue reduces IL-1β levels by enhancing ERK1/2 and AKT phosphorylation to improve diabetic retinopathy in rats / 细胞与分子免疫学杂志

Objective To investigate the neuroprotective effect of methylene blue on diabetic retinopathy in rats. Methods Thirty SD rats were randomly divided into blank, control and experimental groups. The control and experimental groups were induced with diabetes by streptozotocin (STZ) intraperitoneal injection. After 6 weeks of successful modeling, the experimental group received intravitreal injection of methylene blue at a dose of [0.2 mg/(kg.d)], while the control group received an equal amount of dimethyl sulfoxide (DMSO) intravitreal injection, both continuously injected for 7 days. ELISA was used to detect the levels of retinal superoxide dismutase (SOD), 8-iso-prostaglandin F2alpha (iPF2α) and interleukin-1β (IL-1β) in rats. Western blot analysis was used to detect the expression of retinal extracellular signal-regulated kinase 1/2 phosphorylation (p-ERK1/2) and phosphorylated protein kinase B (p-AKT), and PAS staining was used to detect retinal morphological changes. Results Compared with the blank group rats, the retinal SOD activity in the control and experimental group rats was significantly reduced. iPF2α, IL-1β and p-ERK1/2 level increased, while p-AKT level decreased. Compared with the control group, the SOD activity of the experimental group rats increased. iPF2α and IL-1β level went down, while p-ERK1/2 and p-AKT level went up significantly. The overall thickness of the retinal layer and the number of retinal ganglion cells were significantly reduced. Conclusion Methylene blue improves diabetic retinopathy in rats by reducing retinal oxidative stress and enhancing ERK1/2 and AKT phosphorylation.

Evaluation of the therapeutic effect of methylene blue on the liver of rats submitted to ischemia and reperfusion

Abstract Purpose: To analyze the effect of methylene blue (MB) therapy during the liver ischemia-reperfusion injury (I/R) process. Methods: Thirty-five male Wistar rats were used, (70%) submitted to partial ischemia (IR) or not (NIR) (30%) were obtained from the same animal. These animals were divided into six groups: 1) Sham (SH), 2) Sham with MB (SH-MB); 3) I/R, submitted to 60 minutes of partial ischemia and 15 minutes of reperfusion; 4) NI/R, without I/R obtained from the same animal of group I/R; 5) I/R-MB submitted to I/R and MB and 6) NI/R-MB, without I/R. Mitochondrial function was evaluated. Osmotic swelling of mitochondria as well as the determination of malondialdehyde (MDA) was evaluated. Serum (ALT/AST) dosages were also performed. MB was used at the concentration of 15mg/kg, 15 minutes before hepatic reperfusion. Statistical analysis was done by the Mann Whitney test at 5%. Results: State 3 shows inhibition in all ischemic groups. State 4 was increased in all groups, except the I/R-MB and NI/R-MB groups. RCR showed a decrease in all I/R and NI/R groups. Mitochondrial osmotic swelling showed an increase in all I/R NI/R groups in the presence or absence of MB. About MDA, there was a decrease in SH values in the presence of MB and this decrease was maintained in the I/R group. AST levels were increased in all ischemic with or without MB. Conclusions: The methylene blue was not able to restore the mitochondrial parameters studied. Also, it was able to decrease lipid peroxidation, preventing the formation of reactive oxygen species.

Photodynamic action of the red laser on Propionibacterium acnes

Abstract: Background: Photodynamic therapy is a therapeutic modality that has consolidated its activity in the photooxidation of organic matter, which arises from the activity of reactive oxygen species. Objective: To evaluate the effect of red laser 660nm with the photosensitizer methylene blue on Propionibacterium acnes in vitro. Method: The experimental design was distributed into four groups (1 - control group without the application of light and without photosensitizer, 2 - application of light, 3 - methylene blue without light, and 4 - methylene blue with light). Tests were subjected to red laser irradiation 660nm by four cycles of 5 minutes at 3-minute intervals. Results: It was evidenced the prominence of the fourth cycle (20 minutes) groups 2, 3 and 4. Study limitations: Despite the favorable results, the laser irradiation time photosensitizer associated with methylene blue were not sufficient to to completely inhibit the proliferation of bacteria. Conclusion: Further studies in vitro are recommended to enable the clinical application of this photosensitizer in photodynamic therapy.

Methylene blue to treat protamine-induced anaphylaxis reactions. An experimental study in pigs

ABSTRACT Objective: To examine if methylene blue (MB) can counteract or prevent protamine (P) cardiovascular effects. Methods: The protocol included five heparinized pig groups: Group Sham -without any drug; Group MB - MB 3 mg/kg infusion; Group P - protamine; Group P/MB - MB after protamine; Group MB/P - MB before protamine. Nitric oxide levels were obtained by the nitric oxide/ozone chemiluminescence method, performed using the Nitric Oxide Analizer 280i (Sievers, Boulder, CO, USA). Malondialdehyde plasma levels were estimated using the thiobarbiturate technique. Results: 1) Groups Sham and MB presented unchanged parameters; 2) Group P - a) Intravenous protamine infusion caused mean arterial pressure decrease and recovery trend after 25-30 minutes, b) Cardiac output decreased and remained stable until the end of protamine injection, and c) Sustained systemic vascular resistance increased until the end of protamine injection; 3) Methylene blue infusion after protamine (Group P/MB) - a) Marked mean arterial pressure decreased after protamine, but recovery after methylene blue injection, b) Cardiac output decreased after protamine infusion, recovering after methylene blue infusion, and c) Sustained systemic vascular resistance increased after protamine infusion and methylene blue injections; 4) Methylene blue infusion before protamine (Group MB/P) - a) Mean arterial pressure decrease was less severe with rapid recovery, b) After methylene blue, there was a progressive cardiac output increase up to protamine injection, when cardiac output decreased, and c) Sustained systemic vascular resistance decreased after protamine, followed by immediate Sustained systemic vascular resistance increase; 5) Plasma nitrite/nitrate and malondialdehyde values did not differ among the experimental groups. Conclusion: Reviewing these experimental results and our clinical experience, we suggest methylene blue safely prevents and treats hemodynamic protamine complications, from the endothelium function point of view.

Methylene blue-related corneal edema and iris discoloration / Edema de córnea e descoloração de íris associados ao azul de metileno

ABSTRACT We report the case of a 70-year-old female patient who developed corneal edema and iris discoloration following the inadvertent use of 1% methylene blue instead of 0.025% trypan blue to stain the anterior capsule during cataract phacoemulsification surgery. Copious irrigation was performed upon realization of incorrect dye use. Corneal edema and iris discoloration developed during the early postoperative period and persisted at 24-months follow-up. However, keratoplasty was not required. The intracameral use of 1% methylene blue has a cytotoxic effect on the corneal endothelium and iris epithelium. Copious irrigation for at least 30 min using an anterior chamber maintainer may improve outcomes.

RESUMO Paciente do sexo feminino com 70 anos de idade desenvolveu edema da córnea e descoloração da íris após o uso inadvertido de 1% de azul de metileno em vez de 0,025% de azul tripano para corar a cápsula anterior do cristalino durante a cirurgia de catarata por facoemulsificação. Foi realizada irrigação abundante quando detectou-se que o corante incorreto tinha sido usado. Edema da córnea e descoloração íris que ocorreu no período pós-operatório precoce persistiu durante 24 meses de seguimento; no entanto, a ceratoplastia não foi necessária. O uso intracameral de 1% de azul de metileno tem efeitos citotóxicos sobre o endotélio da córnea e epitélio da íris. A irrigação abundante durante pelo menos 30 minutos, utilizando um mantenedor de câmara anterior pode resultar em um prognóstico melhor.

Inibição da guanilato ciclase pelo azul de metileno no choque circulatório causado por pancreatite aguda necrosante: uma palavra de cuidado embasada em modelo suíno / Guanylate cyclase inhibition by methylene blue in circulatory shock caused by acute necrotizing pancreatitis: a word of caution based on a porcine model

OBJETIVO: estudar o uso terapêutico do bloqueio da guanilato ciclase pelo azul de metileno em um modelo experimental de pancreatite aguda grave em suínos. MÉTODOS: a pancreatite aguda necrotizante foi induzida em porcos anestesiados por infusão ductal pancreática retrógrada de 1ml/kg de taurocolato de sódio a 5% e 8U/kg de enteroquinase. Três grupos foram estudados (n=5): controle (C), pancreatite (PA), "bolus" de azul seguido por pancreatite (AM+PA). Os dados incluíram enzimas séricas e do líquido abdominal, variáveis hemodinâmicas, hemogasometria arterial, volume de líquido abdominal, marcadores inflamatórios plasmáticos, nitrito/nitrato e mieloperoxidase e malondialdeído plasmático. Aplicou-se a análise de variância seguida do pós-teste de Bonferroni (p<0,05). RESULTADOS: os valores de amilase e lipase foram três e dez vezes mais elevados no grupo PA. A atividade da mieloperoxidase foi 50% superior no grupo PA. Os dados hemodinâmicos indicaram choque hipovolêmico precoce seguido de choque cardiogênico. Observou-se grave translocação de líquidos para a cavidade peritoneal. A nitrito/nitrato plasmática permaneceu inalterada. O grupo AM+PA teve aumento de cinco vezes do mieloperoxidase em comparação com o grupo C. CONCLUSÕES: a utilização de azul de metileno em suínos com pancreatite não demonstrou efeitos significativos sobre variáveis hemodinâmicas e inflamatórias. Seu uso terapêutico na pancreatite necro-hemorrágica pode ser inadequado e extremo cuidado deve ser tomado dado o aumento da peroxidação lipídica evidenciado pelo aumento dos valores do malondialdeído.

OBJECTIVE: To study the therapeutic application of guanylate cyclase inhibition by methylene blue in an experimental model of acute pancreatitis in pigs. METHODS: acute necrotizing pancreatitis was induced in anesthetized pigs by the retrograde infusion of 1 ml/kg of 5% sodium taurocholate and 8 U/kg enterokinase in the pancreatic duct. Three groups were studied (n = 5): control (C), pancreatitis (AP), and MB bolus followed by pancreatitis (MB+P). The data included serum and abdominal fluid enzymes, hemodynamic variables, arterial hemogasometry, abdominal fluid volume, inflammatory markers, plasma nitrite/nitrate (NOx), plasma myeloperoxidase (MPO) and plasma malondialdehyde (MDA). One- and two-way analysis of variance (ANOVA) was performed, followed by the Bonferroni test (p < 0.05). RESULTS: amylase and lipase were three and 10-fold higher in the AP group. Myeloperoxidase activity was 50% higher in the AP group. The hemodynamic data indicated early hypovolemic shock followed by cardiogenic shock. Severe fluid translocation to the peritoneal cavity was observed. Plasma NOx remained unchanged. The MB+P group had a five-fold increase in MDA compared with the C group. CONCLUSION: preemptive application of MB in pigs with AP demonstrated no significant effects on hemodynamic and inflammatory variables. The use of MB is inadequate in cases of exponential NO release, and extreme caution must be exercised, given the increase in lipid peroxidation based on the malondialdehyde dosage.

Cinnamyl alcohol attenuates vasoconstriction by activation of K+ channels via NO-cGMP-protein kinase G pathway and inhibition of Rho-kinase

Cinnamyl alcohol (CAL) is known as an antipyretic, and a recent study showed its vasodilatory activity without explaining the mechanism. Here we demonstrate the vasodilatory effect and the mechanism of action of CAL in rat thoracic aorta. The change of tension in aortic strips treated with CAL was measured in an organ bath system. In addition, vascular strips or human umbilical vein endothelial cells (HUVECs) were used for biochemical experiments such as Western blot and nitrite and cyclic guanosine monophosphate (cGMP) measurements. CAL attenuated the vasoconstriction of phenylephrine (PE, 1 microM)-precontracted aortic strips in an endothelium-dependent manner. CAL-induced vasorelaxation was inhibited by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME; 10(-4) M), methylene blue (MB; 10(-5) M) and 1 H-[1,2,4]-oxadiazolole-[4,3-a] quinoxalin-10one, (ODQ; 10(-6) or 10(-7) M) in the endothelium-intact aortic strips. Atrial natriuretic peptide (ANP; 10(-8) or 10(-9) M) did not affect the vasodilatory effect of CAL. The phosphorylation of endothelial nitric oxide synthase (eNOS) and generation of nitric oxide (NO) were stimulated by CAL treatment in HUVECs and inhibited by treatment with L-NAME. In addition, cGMP and PKG1 activation in aortic strips treated with CAL were also significantly inhibited by L-NAME. Furthermore, CAL relaxed Rho-kinase activator calpeptin-precontracted aortic strips, and the vasodilatory effect of CAL was inhibited by the ATP-sensitive K+ channel inhibitor glibenclamide (Gli; 10(-5) M) and the voltage-dependent K+ channel inhibitor 4-aminopyridine (4-AP; 2 x 10(-4) M). These results suggest that CAL induces vasorelaxation by activating K+ channels via the NO-cGMP-PKG pathway and the inhibition of Rho-kinase.

The influence of methylene blue on the healing of intestinal anastomoses subjected to ischemia and reperfusion in rats / A influência do azul de metileno na cicatrização de anastomoses intestinais submetidas à isquemia e reperfusão em ratos

PURPOSE: To investigate the influence of methylene blue, on the healing of intestinal anastomoses subjected to ischemia and reperfusion in rats. METHODS: Forty-five rats divided into the following three groups were used: control (G1); ischemia without methylene blue (G2); and ischemia with methylene blue (G3). A laparotomy was performed and the cranial mesenteric artery isolated. Whereas the cranial artery was temporarily occluded for 45 minutes in groups G2 and G3, prior to enterotomy and intestinal anastomosis, in group G1 the enterotomy and intestinal anastomosis were performed without prior lesion. Afterwards, 2mL of 0.5 percent methylene blue were instilled in the peritoneal cavities of the animals in group G3, and 2mL of isotonic saline solution in the peritoneal cavities of the animals in group G2. After the reperfusion, an enterectomy and intestinal anastomosis were performed. After the animals had been sacrificed on the seventh day after the operation, the abdominal cavity was examined by resection of a segment of the intestine containing the anastomosis in order to measure its strength and for histopathological examination. RESULTS: Free fluid or abscesses in the peritoneal cavity were rare. When inflammation was analyzed, the group subjected to ischemia without methylene blue had a higher score for mononuclear cells (p=0.021) and granulation tissue (p=0.044). No significant difference was observed in the density of type I or type III collagens. CONCLUSION: The methylene blue did not show beneficial effect on the healing of intestinal anastomoses subjected to ischemia and reperfusion in rats.

OBJETIVO: Investigar a influência do azul de metileno, na cicatrização de anastomoses intestinais de ratos submetidas a isquemia e à reperfusão. MÉTODOS: Quarenta e cinco ratos foram divididos em três grupos: controle (G1); isquemia sem azul de metileno (G2) e isquemia com azul de metileno (G3). Foi feita uma laparotomia e a artéria mesentérica cranial isolada. Enquanto a artéria mesentérica cranial foi ocluída por 45 minutos nos grupos G2 e G3, antes da anastomose, no grupo G1 a anastomose foi realizada sem esta lesão prévia. Em seguida 2 mL de azul de metileno 0,5 por cento foi instilado na cavidade peritoneal dos animais do grupo G3, 2 mL de solução salina isotônica na cavidade dos animais do grupo G2. Após a reperfusão uma enterectomia seguida de anastomose foi realizada. Os animais foram submetidos à eutanásia no 7.º dia após a operação, a cavidade abdominal foi examinada e um segmento intestinal que continha a anastomose foi ressecado. Este serviu para a medida de resistência e para exame anátomo-patológico. RESULTADOS: Líquido livre ou abscessos foram raros. A análise da inflamação mostrou que o grupo submetido à isquemia sem azul de metileno apresentou maior score para células mononucleares (p=0,021) e tecido de granulação (0,044). Não se observou diferença significante na análise do colágeno I e III. CONCLUSÃO: O azul de metileno não mostrou efeitos benéficos na cicatrização de anastomoses intestinais submetidas à isquemia e à reperfusão em ratos.

Métodos de inactivación de patógenos en Plasma Fresco y Concentrados de Plaquetas / Pathogen Inactivation technology in fresh plasma and platelets concentrates

Las Tecnologías de Inactivación de Patógenos (TIPS) proveen un camino adicional para proteger el abastecimiento de sangre de agentes conocidos, emergentes y aún desconocidos. El principio precautorio refrendado por la FDA luego de la crisis del VIH/SIDA, establece que para situaciones de incertidumbre científica debiera tenerse en cuenta la posibilidad de riesgo aún en ausencia de pruebas de lo contrario. Pudiera argumentarse entonces que las TIPS representan la quintaesencia del principio precautorio. Si bien se ha acortado el intervalo entre el reconocimiento de un agente a la implementación de medidas para prevenirlo, hay a menudo un periodo de retardo temprano, durante el que una enfermedad no parece representar un riesgo para el receptor o la salud humana en general. El daño causado por ellos se ha mencionado como "una propiedad fija e inevitable de la práctica transfusional". Las TIPS para plasma fresco incluyen las siguientes: MBLT (Tratamiento con Luz y Azul de Metileno). PLT (Tratamiento con Psoralenos y Luz). RFLT (tratamiento con Riboflavina y Luz) además existe un método de Solvente Detergente para pools de plasma. Mientras que para los concentrados de plaquetas se pueden usar el Tratamiento con Luz Ultravioleta y Amotosaleno-UVA. Existe un riesgo potencial en retrasar la implementación de las TIPS mientras se aguarda la evidencia y el sistema absolutamente perfecto de ponerlas en práctica. Llegó el momento de actuar.

Pathogen Inactivation Technology (PIT) provides an additional way to protect the blood supply from agents known, emerging and yet unidentified. The precautionary principie which was first endorsed by FDA after the crisis of HIV / AIDS, states that for situations of scientific uncertainty should be taken into account the possibility of risk even in the absence of proof to the contrary. It could be argued then, that PITs represent the quintessence of the precautionary principie. Almost all of the potential for TTD is eradicated, often before the responsible agent is even recognized. Although the interval between the recognition of an agent to implement measures to prevent it has been shortened, there is often an earlier period of delay, during which a disease does not appear to represent a risk to the recipient or to human health in general. The damage caused bythem has been called a "fixed and inevitable property of transfusion practice." Techniques for pathogen inactivation of plasma include the following. MBLT (Methylene Blue and Light Treatment). PLT (Psoralens and Light Treatment). RFLT (Riboflavin and Light Treatment) in addition, there is a method of Solvent Detergent (SD) for pools of plasma. Techniques for pathogen inactivation of platelets include the following Ultra Violet Light Treatment and Amotosalen- UVA.There is great potential risk in delaying the implementation of Pathogen Inactivation Technologies (PITs) while awaiting the evidence and the absolute pedect system to put it into operation. It is time to act.

Inherent rhythmicity and interstitial cells of Cajal in a frog vein.

Interstitial cells of Cajal are responsible for rhythmic contractions of the musculature of the gastrointestinal tract and blood vessels.The existence of these cells and spontaneous rhythmicity were noticed in amphibian vein and the findings are reported in this paper.The postcaval vein was identified in the frog, Rana tigrina and was perfused with amphibian Ringer solution after isolation.Contractile activity was recorded through a tension transducer connected to a polygraph.The isolated postcaval vein showed spontaneous rhythmic activity. Addition of cold Ringer solution decreased, while warm Ringer increased, the rate of contraction. Adrenaline caused inhibition of rhythmic activity at a dosage that increased the rate of isolated sinus venosus.Sections of the postcaval vein,when stained supravitally with methylene blue, showed the presence of interstitial cells of Cajal. Photic stimulation of the vein in the presence of methylene blue led to a significant decrease in the rate of spontaneous beating of the vein.These findings indicate that the postcaval vein of frog is capable of inherent rhythmcity, which is dependent on the interstitial cells of Cajal but is independent of the sinus venosus.

Photodynamic effect of light-emitting diode light on cell growth inhibition induced by methylene blue.

The aim of this study was to propose the use of red light-emitting diode (LED) as an alternative light source for methylene blue (MB) photosensitizing effect in photodynamic therapy (PDT). Its effectiveness was tested against Staphylococcus aureus (ATCC 26923), Escherichia coli (ATCC 26922), Candida albicans (ATCC 90028) and Artemia salina. The maximum absorption of the LED lamps was at a wavelength of 663 nm, at intensities of 2,4,6 and 12 J.cm-2 for 10, 20, 30 and 60 min of exposure, respectively. Assays with and without LED exposure were carried out in plates containing MB at concentrations of 7 to 140.8 (micro) M for microorganisms and 13.35 to 668.5 (micro) M for microorganisms or microcrustaceans.The LED exposure induced more than 93.05%, 93.7% and 93.33% of growth inhibition for concentrations of 42.2 (micro)M for S.aureus (D-value=12.05 min) and 35.2 (micro)M for E.coli (D-value=11.51 min) and C.albicans (D-value=12.18 min), respectively after 20 min of exposure. LED exposure for 1 h increased the cytotoxic effect of MB against A.salina from 27% to 75%.Red LED is a promising light device for PDT that can effectively inhibit bacteria, yeast and microcrustacean growth.

Bradycardia induced by Mesobuthus tamulus scorpion venom involves muscarinic receptor-G-protein-coupled cell signaling pathways.

Indian red scorpion (Mesobuthus tamulus; MBT) envenomation produces various cardio-respiratory abnormalities including cardiac dysrhythmias. The underlying cell signaling pathways for the cardiac dysrhythmias produced by MBT venom are not known. The present study was therefore conducted to delineate the second messenger signaling pathways involved in MBT venom-induced atrial rhythm changes. The effects of venom and various antagonists were examined on spontaneously beating rat right atrial preparations in vitro. The MBT-venom produced an increase (35%), a decrease (45%) and again an increase (50%) in rate at 0.03, 0.3 and 3.0 microg/ml of venom, respectively. On the other hand, force of contraction exhibited a concentration-dependent rise (up to 40%) at all concentrations of venom. Pretreatment with atropine (0.3 microM) blocked the decrease in atrial rate at 0.3 microg/ml concentration of venom while no such blockade was seen in force of contraction. Submaximal concentration of ACh (0.1 nM) decreased the atrial rate by 25%. In the presence of MBT venom (0.3 microg/ml), ACh-induced fall in atrial rate was enhanced. The venom-induced fall in atrial rate and augmentation of ACh response were blocked by pertussis toxin (PTx; a Gi-inhibitor) or methylene blue (a G-cyclase inhibitor). The results indicate that the decrease in atrial rate produced by venom is mediated muscarinic by receptors via Gi-guanylyl cyclase mediated cell signaling pathways.

In vitro antimalarial activity of methylene blue against field isolates of Plasmodium falciparum from children in Southwest Nigeria.

BACKGROUND & OBJECTIVES: Methylene blue (MB), a thiazine dye is used in the treatment of various methemoglobinaemias. However, sporadic reports have shown some antimalarial therapeutic effect when administered to patients with clinical manifestations of malaria. The inhibitory concentration of schizont maturation and antimalarial activity of MB have not been fully elucidated. The present study therefore aimed at determining the antimalarial activity of MB in Plasmodium falciparum isolates obtained from children with malaria using standard in vitro drug susceptibility test. METHODS: Twenty children (8 boys and 12 girls) within the age range 4.5-11.5 yr were enrolled into the study and 2 ml of blood withdrawn aseptically. The standard microtest technique of schizont inhibition assay was used to culture fresh isolates obtained from P. falciparum infected patients. Chloroquine (CQ) and quinine (QN) were used as reference standards for in vitro drug susceptibility tests. RESULTS: The mean 50 per cent inhibitory concentration (IC(50)) values were 9.59 +/- 3.25nM, 196 +/-21.11nM and 607 +/- 27.41nM for MB, CQ and QN respectively. Ten of the 14 isolates were sensitiveto MB, 11 were sensitive to CQ while nine were sensitive to QN. Three isolates were resistant to CQ,and of these, two were sensitive to MB and one was sensitive to QN. INTERPRETATION & CONCLUSION: This preliminary study showed that MB has high antimalarial activity comparable with CQ and QN and may be used as a potent schizonticidal drug against CQ-resistant isolates.

Estudos hemodinâmicos e da função endotelial em porcas saudáveis após injeção em bolus endovenoso de azul de metileno / Hemodynamic and vascular endothelium function studies in healthy pigs after intravenous bolus infusion of methylene blue / Hemodynamic and vascular endothelium function studies in healthy pigs after intravenous bolus infusion of methylene blue

OBJETIVO: Benefícios clínicos obtidos pelo azul de metileno (AM) no tratamento da vasoplegia induzida pela ação do óxido nítrico (NO) têm sido relatados na sepse, na síndrome da resposta inflamatória sistêmica (SIRS) em cirurgia cardíaca e no choque anafilático, mas a sua segurança é muitas vezes questionada, principalmente relacionada aos seus efeitos hemodinâmicos e à possibilidade de causar disfunção endotelial. O objetivo deste estudo foi examinar os efeitos hemodinâmicos e a função endotelial da infusão endovenosa in vivo do AM em porcos. MÉTODOS: O protocolo de estudo incluiu dois grupos experimentais de porcas fêmeas: Grupo I (Controle) - os animais (n = 6) não receberam AM; Grupo II (AM) - os animais receberam 3 mg/kg de AM em forma de bolus endovenoso. Após quinze minutos de registro dos parâmetros hemodinâmicos os animais foram sacrificados por exsangüinação, e os estudos in vitro foram conduzidos usando segmentos de artérias coronária, hepática, mesentérica superior, renal, para determinar o efeito do AM na função endotelial relacionada com a liberação de NO. Mediu-se também o NO plasmático nos dois grupos experimentais. RESULTADOS: Os resultados obtidos no presente estudo foram: 1) a infusão endovenosa de AM (3,0 mg/kg) não causou nenhuma alteração hemodinâmica significativa; 2) os valores absolutos e porcentuais e nitrito/nitrato plasmático (NOx) não apresentaram diferenças nos dois grupos experimentais; 3) o estudo in vitro dos segmentos arteriais (coronária, hepática, renal e mesentérica superior) não apresentou disfunção endotelial nos dois grupos. Os resultados sugerem que a injeção endovenosa de AM é segura. Esse dado concorda com dados clínicos no qual o AM foi utilizado para tratar a síndrome vasoplégica após circulação extracorpórea, síndrome da resposta infamatória sistêmica (SIRS) e anafilaxia. Os resultados não foram inesperados porque os animais não apresentavam vasoplegia, não se esperando que a inibição da guanilatociclase tenha algum efeito...

OBJECTIVE: Clinical benefit of methylene blue (MB) treating NO-induced vasoplegia has been reported in sepsis, systemic inflammatory response syndrome (SIRS) in cardiac surgery and anaphylactic shock, but its safety is sometimes questioned, mainly regarding its hemodynamic effects and the possibility of causing endothelium dysfunction. To examine the nitric oxide plasma levels and cardiovascular effects of the infusion of MB in vivo and its effects on endothelium-dependent and endothelium-independent in vitro vascular relaxation. METHODS: The study protocol included two experimental groups of female pigs: Group I (Control) - the animals (n=6) did not receive MB; Group II (MB) - the animals received 3 mg/kg of MB intravenous bolus infusion. After fifteen minutes of hemodynamic parameter recording the animals were sacrificed by exsanguination, and in vitro studies were conducted using segments of coronary, hepatic, superior mesenteric and renal arteries, to determine the effect of MB on the arterial endothelium function with regard to NO release. Nitric oxide plasma levels (NOx) were measured in each of the experimental groups. RESULTS: The results obtained in the present investigation were: 1) intravenous infusion of MB (3.0 mg/kg) caused no hemodynamic changes; 2) absolute and percent plasma NOx values did not differ between the experimental groups; and 3) in vitro study of vascular relaxation showed no significant difference between groups. These results show that MB intravenous infusion seems to be safe. This finding agrees with data from clinical experiments where MB was used to treat vasoplegic syndrome after cardiopulmonary bypass, systemic inflammatory response syndrome (SIRS) and anaphylaxis. These results were not unexpected because, as in healthy subjects, hemodynamics is only fine tuned and not fully under NO control; therefore, MB inhibiting guanylyl cyclase is not expected to do anything...

Practical tips for modified dorsolumbar epidural anesthesia in cattle

Segmental dorsolumbar epidural anesthesia has been considered difficult to perform. The purpose of this study was to determine whether or not it is difficult for beginners to learn how to do modified dorsolumbar epidural anesthesia of cattle. Thirty cattle were divided into two groups, young (n = 8) and adult (n = 22), according to their age and body weight, and 0.12% new methylene blue (NMB) was injected into the first interlumbar (L1.L2) epidural space by four fifth-year veterinary school students who had never performed this method. After a 1 hour lecture on the modified dorsolumbar epidural anesthesia procedure which included basic anatomy and skills, each student successfully performed the procedure. In the young group, the NMB solution was distributed between the periosteum and the epidural fat (BPF) in one half and between the epidural fat and the dura mater (BFD) in the other half of the cattle. In about 60% (13/22) of the adult group, the NMB solution distributed as BFD type. This study showed that the modified dorsolumbar epidural anesthesia procedure is easy for beginners to perform if they overcome their fear about the deeper insertion of the epidural needle with basic anatomical knowledge and a little experience.

Sodium nitroprusside relaxes goat coronary artery through activation of calcium-dependent K+ channels.

In the present investigation we have examined the hypothesis that calcium-dependent K+ channels (K(Ca)) are involved in the sodium nitroprusside (SNP)-induced vasodilatation of goat coronary artery. SNP (10(-9)-3 x 10(-6) M), added cumulatively, relaxed K+ (30 mM)-contracted coronary artery ring segments in a concentration-dependent manner with an EC50 of 1.32 x 10(-7) M (95% CL, 0.93-1.86 x 10(-7) M; n = 21). K(Ca) blocker, tetraethyl ammonium (1 mM) caused a rightward shift in the concentration-response curve of SNP with a corresponding increase in EC50 (1.62 x 10(-6) M; 95% CL, 0.44-6.02 x 10(-6) M, n = 4) of nitro vasodilator. Lowering of extra cellular Ca2+ in the physiological saline solution to 1/4 of normal selectively attenuated the vasorelaxant response of SNP, thereby causing an increase in its EC50 (2.4 x 10(-6) M; 95% CL, 1.23-4.68 x 10(-6) M, n = 4). Exposure of the tissues to high K+ (80 mM) solution, a protocol adopted to reduce the K+ gradient across the cell membrane, markedly inhibited the coronary artery relaxations induced by SNP (EC50, 2.54 x 10(-6) M; 95% CL, 1.31-4.91 x 10(-6) M, n = 4), when compared with tissues contracted with low K+ (30 mM) solution (EC50 7.9 x 10(-8); 95% CL, 4.4 x 10(-8)-1.44 x 10(-7) M, n = 6). The results suggested that a major component of SNP-induced relaxation of goat coronary artery was mediated by K(Ca) channels.

Cholinergic-NO-cGMP mediation of sildenafil-induced antinociception.

Acetylcholine and cholinomimetic agents with predominant muscarinic action are known to increase the concentration of cGMP by activation of nitric oxide signaling pathway in the nociceptive conditions. The present study was aimed to investigate the NO-cGMP-PDE5 pathway in nociceptive conditions in the experimental animals. Nociceptive threshold was assessed by acetic acid-induced writhing assay (chemonociception) or carrageenan-induced hyperalgesia. Sildenafil [1-5 mg/kg, ip, 50-200 microg/paw, intraplantar (ipl)] produced dose dependent antinociception in both the tested models. Coadministration of acetylcholine (50 mcg/paw, ipl) or cholinomimetic agent, neostigmine (0.1 mcg/kg, ip and 25 ng/paw, ipl) augmented the peripheral antinociceptive effect of sildenafil. This effect was sensitive to blockade by L-NAME (20 mg/kg, ip, 100 microg/paw, ipl), a non-selective NOS inhibitor and methylene blue (1 mg/kg, ip), a guanylate cyclase inhibitor, which per se had little or no effect in both the models of nociception. Further, the per se analgesic effect of acetylcholine and neostigmine was blocked by both L-NAME and methylene blue in the models of nociception, suggesting the activation of NO-cGMP pathway. Also, both L-NAME and methylene blue blocked the per se analgesic effect of sildenafil. These results indicate the peripheral accumulation of cGMP may be responsible for antinociceptive effect, and a possible interaction between cholinergic agents and PDE5 system in models of nociception.

Experimental evidence for a non-renin mediated pathway during TAME-esterase induced contractions in rat aorta in vitro.

Possible pharmacological effects of N-alpha-tosyl L-arginine methyl ester [TAME] were studied on rat aorta strips in vitro. Results showed that [TAME]-esterase was an endothelium dependent component that involved a nitric oxide cyclic-GMP mediated pathway. Furthermore, during activation of Kinin-Kallikrein system, TAME-esterase induced contractions involve degradation of kinins by kininases.

Exposição aguda à dapsona e metemoglobinemia em crianças: tratamento com doses múltiplas de carvão ativado associado ou não ao azul metileno / Acute dapsone exposure and methemoglobinemia in children: treatment with multiple doses of activated charcoal with or without the administration of methylene blue

Objetivo: Estudar a evolução da metemoglobinemia em 17 crianças com exposição aguda à dapsona, complicada com metemoglobinemia acima de 20 por cento da taxa total de hemoglobina, tratadas com doses múltiplas de carvão ativado associado ou não ao azul de metileno. Casuística e Métodos: Dezessete crianças (1-13 anos, mediana=3 anos), foram admitidas 1-72 horas após a ingestão de 100-1.200 mg (mediana = 350 mg, 10 pacientes) ou de uma quantidade desconhecida (7 pacientes) da dapsona. À admissão, o nível de metemoglobinemia variou de 23,5-49,7 por cento (mediana=37,8 por cento), e as principais manifestações clínicas observadas foram cianose (17), taquicardia (17), vômitos (11) e taquipnéia (8). Todas as crianças receberam doses múltiplas de carvão ativado por via oral ou por tubagem nasogástrica (1 g/kg,4-6x/dia, solução a 10 por cento, 3-16 doses, mediana=8doses). Em 12 pacientes também foi administrado o azul de metileno (1-2 mg/kg, solução 1-2 por cento) em dose única, IV, em torno de 5 minutos. Resultados: Constatou-se uma diminuiçao progressiva dos níveis de metemoglobinemia em ambos os grupos de tratamento (doses múltiplas de carvão ativado isoladamente ou associado ao azul de metileno. Não foi observada diferença estatística significativa, em relação à queda da metemoglobinemia de acordo com o tempo, entre os dois tipos de tratamento efetuado (p=0,49, teste de Wilcoxon). Conclusão: A administração de doses múltiplas de carvão ativado pode ser considerada como uma alternativa terapêutica, isolada ou associada ao azul de metileno, no tratamento de crianças com exposição aguda à dapsona, complicada com metemoglobinemia acima de 20 por cento da taxa de hemoglobina