RESUMEN
The aim of this study was to evaluate alpaca pregnancy outcomes and birth rates of females inseminated with frozen semen using two commercial extenders. A total of 18 ejaculates from 8 adult alpaca males were obtained with artificial vagina, and macroscopic and microscopic semen characteristics were assessed. Afterwards, samples were divided into two aliquots, diluted with Biladyl® B or AndroMed®, and cooled for 2 h at 5°C. At that moment, sperm motility was evaluated, and samples were frozen through a gradual descent of temperature using a liquid nitrogen tank. To analyse frozen sperm quality, samples were thawed at 38°C for 30 s. Even though a significant decrease in sperm motility and viability was detected when thawed (p < .05), no superiority was found between the two commercial extenders (Biladyl® B vs. AndroMed®). A total of 36 alpaca females were artificially inseminated (AI) between 30 and 34 h post-injection of a GnRH analogue, administered when a growing dominant follicle was detected through transrectal palpation and ultrasonography. Obtained pregnancy rates were similar between Biladyl® B (33.3%, 6/18) and AndroMed® (22.2%, 4/18). No significant differences were detected in birth rates between the two tested extenders, obtaining 4 and 3 births for Biladyl® and AndroMed®, respectively. In conclusion, alpaca pregnancies and alive offspring can be obtained through AI with frozen semen at similar efficiency rates using commercial diluents, Biladyl® B or AndroMed®.
Asunto(s)
Camélidos del Nuevo Mundo , Preservación de Semen , Embarazo , Femenino , Masculino , Animales , Preservación de Semen/veterinaria , Semen , Tasa de Natalidad , Crioprotectores , Criopreservación/veterinaria , Motilidad Espermática , Espermatozoides , Inseminación Artificial/veterinariaRESUMEN
AIM: Neutrophils are the first cells to arrive at sites of injury. Nevertheless, many inflammatory diseases are characterized by an uncontrolled infiltration and action of these cells. Cell migration depends on volume changes that are governed by ion channel activity, but potassium channels in neutrophil have not been clearly identified. We aim to test whether KCa3.1 participates in neutrophil migration and other relevant functions of the cell. METHODS: Cytometer and confocal measurements to determine changes in cell volume were used. Cells isolated from human, mouse and horse were tested for KCa3.1-dependent chemotaxis. Chemokinetics, calcium handling and release of reactive oxygen species were measured to determine the role of KCa3.1 in those processes. A mouse model was used to test for neutrophil recruitment after acute lung injury in vivo. RESULTS: We show for the first time that KCa3.1 is expressed in mammalian neutrophils. When the channel is inhibited by a pharmacological blocker or by genetic silencing, it profoundly affects cell volume regulation, and chemotactic and chemokinetic properties of the cells. We also demonstrated that pharmacological inhibition of KCa3.1 did not affect calcium entry or reactive oxygen species production in neutrophils. Using a mouse model of acute lung injury, we observed that Kca3.1(-/-) mice are significantly less effective at recruiting neutrophils into the site of inflammation. CONCLUSIONS: These results demonstrate that KCa3.1 channels are key actors in the migration capacity of neutrophils, and its inhibition did not affect other relevant cellular functions.
Asunto(s)
Calcio/metabolismo , Quimiotaxis , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/metabolismo , Neutrófilos/metabolismo , Animales , Humanos , Inflamación , Potenciales de la Membrana/fisiología , Neutrófilos/citologíaRESUMEN
Honey bee (Apis mellifera) colonies of African and European descent were compared for levels of Varroa destructor infestation in 3 different ecological regions in Mexico. The 300 colonies that were studied were located in subtropical, temperate sub-humid, and temperate dry climates. The morphotype and mitotype of adult bees as well as their rates of infestation by varroa mites were determined. Additionally, the number of combs with brood and covered with bees was recorded for each colony. The highest frequency of colonies that were classified as African-derived was found in the subtropical environment, whereas the lowest occurred in the temperate dry region. Overall, the colonies of African genotype had significantly lower mite infestation rates (3.5±0.34%) than the colonies of European genotype (4.7±0.49%) regardless of the region sampled. Significant effects of genotype and region on Varroa infestation rates were evident, and there were no differences in bee population or capped brood between genotypes. Mite infestation levels were significantly lower in the colonies of the temperate dry region than in the colonies of the other 2 regions. These results are discussed within the context of results from studies that were previously conducted in Brazil. This is the first study that demonstrates the effects of Africanization and ecological environment on V. destructor infestation rates in honey bee colonies in North America.
Asunto(s)
Abejas/parasitología , Varroidae , Animales , Ecología , México , Infestaciones por Ácaros , Clima Tropical , Varroidae/genéticaRESUMEN
Currents mediated by calcium-activated chloride channels (CaCCs), observed for the first time in Xenopus oocytes, have been recorded in many cells and tissues ranging from different types of neurons to epithelial and muscle cells. CaCCs play a role in the regulation of excitability in neurons including sensory receptors. In addition, they are crucial mediators of chloride movements in epithelial cells where their activity regulates electrolyte and fluid transport. The roles of CaCCs, particularly in epithelia, are briefly reviewed with emphasis on their function in secretory epithelia. The recent identification by three independent groups, using different strategies, of TMEM16A as the molecular counterpart of the CaCC is discussed. TMEM16A is part of a family that has 10 other members in mice. The discovery of the potential TMEM16 anion channel activity opens the way for the molecular investigation of the role of these anion channels in specific cells and in organ physiology and pathophysiology. The identification of TMEM16A protein as a CaCC chloride channel molecule represents a great triumph of scientific perseverance and ingenuity. The varied approaches used by the three independent research groups also augur well for the solidity of the discovery.
Asunto(s)
Animales , Humanos , Ratones , Canales de Cloruro/metabolismo , Células Epiteliales , Proteínas de la Membrana/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas de Xenopus/metabolismo , Canales de Cloruro/genética , Células Epiteliales/metabolismo , Mucosa Intestinal , Proteínas de la Membrana/genética , Proteínas de Neoplasias/genética , Xenopus , Proteínas de Xenopus/genéticaRESUMEN
Currents mediated by calcium-activated chloride channels (CaCCs), observed for the first time in Xenopus oocytes, have been recorded in many cells and tissues ranging from different types of neurons to epithelial and muscle cells. CaCCs play a role in the regulation of excitability in neurons including sensory receptors. In addition, they are crucial mediators of chloride movements in epithelial cells where their activity regulates electrolyte and fluid transport. The roles of CaCCs, particularly in epithelia, are briefly reviewed with emphasis on their function in secretory epithelia. The recent identification by three independent groups, using different strategies, of TMEM16A as the molecular counterpart of the CaCC is discussed. TMEM16A is part of a family that has 10 other members in mice. The discovery of the potential TMEM16 anion channel activity opens the way for the molecular investigation of the role of these anion channels in specific cells and in organ physiology and pathophysiology. The identification of TMEM16A protein as a CaCC chloride channel molecule represents a great triumph of scientific perseverance and ingenuity. The varied approaches used by the three independent research groups also augur well for the solidity of the discovery.
Asunto(s)
Canales de Cloruro/metabolismo , Células Epiteliales/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas de Xenopus/metabolismo , Animales , Anoctamina-1 , Canales de Cloruro/genética , Humanos , Mucosa Intestinal/metabolismo , Proteínas de la Membrana/genética , Ratones , Proteínas de Neoplasias/genética , Xenopus , Proteínas de Xenopus/genéticaRESUMEN
Injury of the renal tubulointerstitial compartment is recognized to play an important role in hypertension. Its damage may in turn, impair the activity of vasodepressor systems, like the kallikrein-kinin, in blood pressure regulation. The overload proteinuria model induces tubulointerstitial injury with activation of the renin-angiotensin system, but renal kallikrein and the development of hypertension have not received special attention. Sprague-Dawley rats received seven intraperitoneal doses of bovine serum albumin (BSA) 2 g/day under normosodic diet and were hydrated ad libitum. A second group received a high potassium diet to stimulate kallikrein production during the previous four weeks and while under BSA administration. A third one received potassium and BSA in the same schedule, but with the kinin B2 receptor antagonist, HOE140, added during the protein load phase. A control group received seven saline injections. Kallikrein protein was detected by immune labeling on renal sections and enzymatic activity in the urine. The BSA group showed massive proteinuria followed by intense tubulointerstitial damage. Blood pressure increased after the third dose in BSA animals, remaining elevated throughout the experiment, associated with significant reductions in renal expression and urinary activity of kallikrein, compared with controls. An inverse correlation was found between blood pressure and immunohistochemistry and urinary activity of kallikrein. Potassium induced a significant increase in both urinary activity and renal kallikrein expression, associated with significant reduction in blood pressure. The HOE140 antagonist blunted the antihypertensive effect of kallikrein stimulation in proteinuric rats. Loss of renal kallikrein, produced by tubulointerstitial injury, may participate in the pathogenesis of the hypertension observed in this model.
Asunto(s)
Calicreínas/biosíntesis , Riñón/metabolismo , Potasio en la Dieta/administración & dosificación , Proteinuria/metabolismo , Animales , Bradiquinina/análogos & derivados , Bradiquinina/farmacología , Femenino , Hipertensión/etiología , Hipertensión/prevención & control , Calicreínas/orina , Riñón/patología , Proteinuria/complicaciones , Proteinuria/patología , Ratas , Ratas Sprague-Dawley , Sistema Renina-Angiotensina/fisiología , SístoleRESUMEN
Cytochrome-P450 enzymes metabolize cyclosporine both in the liver and in the intestinal wall. Diltiazem, by competitive inhibition of these enzymes, may increase the absorption and the bioavailability of cyclosporine. Some evidence points to a higher activity of some specific enzymes in women, such as CYP3A, that may influence differences in cyclosporine pharmacokinetics. We examined possible gender-associated differences in pharmacokinetic profiles of cyclosporine in 19 stable renal transplant recipients cotreated with diltiazem. Ten women and nine men, chronically using diltiazem associated with cyclosporine, azathioprine, and prednisone were randomly assigned to an 8-week period of continued controlled treatment with diltiazem (10 patients) or a wash-out period discontinuing diltiazem (nine patients). At the end of this period, the time-concentration curves of cyclosporine in the first 4 hours were performed after a single dose of cyclosporine. Thereafter, a cross-over between groups was performed, and time-concentration curves repeated. A specific RIA was used to measure cyclosporine concentrations. Comparisons between male and female patients in doses of cyclosporine and other pharmacokinetics parameters (C(0), C(2), AUC(0-4)), with or without diltiazem, did not show any difference related to gender. The association of diltiazem allowed a similar degree of reduction in Neoral dosage in male and female patients (21%). No changes in serum creatinine, blood urea nitrogen, potassium, uric acid, or blood pressure, or other adverse event were observed during the study. In these groups of patients, gender was not an important factor to be considered when diltiazem is added to cyclosporine therapy.
Asunto(s)
Ciclosporina/farmacocinética , Ciclosporina/uso terapéutico , Diltiazem/uso terapéutico , Trasplante de Riñón/inmunología , Área Bajo la Curva , Bloqueadores de los Canales de Calcio/uso terapéutico , Ciclosporina/sangre , Interacciones Farmacológicas , Femenino , Humanos , Inmunosupresores/sangre , Inmunosupresores/farmacocinética , Inmunosupresores/uso terapéutico , Trasplante de Riñón/fisiología , Masculino , Caracteres SexualesRESUMEN
BACKGROUND: The area-under-the-curve (AUC) of cyclosporine (CsA) reflects exposure to the drug, but this monitoring strategy is time-consuming and not cost-effective. Recently, it has been suggested that the concentration at 2 hours after dosing (C2) shows the best correlation with AUC. The C2 has been replacing the trough measurement (C0) to monitor CsA therapy, but in patients receiving diltiazem there is not much information about this issue. We investigated the correlations between C2 and C0 with absorption AUC over the first 4 hours (AUC(0-4)) in renal stable transplant patients receiving CsA therapy with or without diltiazem. PATIENTS AND METHODS: Ten patients (five men) of ages 23 to 68 years and 6 to 84 months after transplantation, were randomly assigned to an 8-week initial period of either diltiazem washout or controlled treatment with diltiazem. Time-concentration curves of cyclosporine were performed at the end of this period using a specific RIA measurement of blood samples. Thereafter, a crossover of the groups was performed and after another 8 weeks, a second curve was obtained. Drugs that change the pharmacokinetics of cyclosporine or diltiazem were not allowed. RESULTS: The cyclosporine daily dose was lower with diltiazem (173 +/- 4 mg vs 213 +/- 4 mg, P = .002), but despite a dose reduction of only 19% +/- 1.5%, there was a trend to a larger AUC/dose (28 +/- 5 ng x h/mL x mg vs 17 +/- 2 ng x h/mL x mg, P = .1) and a trend to an increased C2 when treatment included diltiazem (1035 +/- 156 ng/mL vs 652 +/- 126 ng/mL, P = NS). Moreover, we confirmed that C2 showed the best correlation with AUC(0-4), (r = 0.7, P = .04), a correlation that improved with diltiazem (r = 0.9, P < .002). CONCLUSION: C2 is the point that correlates best with AUC(0-4) with or without diltiazem. C2 in the presence of diltiazem was associated with a stronger, more significant correlation with AUC(0-4).
Asunto(s)
Diltiazem/farmacocinética , Trasplante de Riñón/inmunología , Vasodilatadores/farmacocinética , Adulto , Anciano , Área Bajo la Curva , Ciclosporina/sangre , Ciclosporina/farmacocinética , Ciclosporina/uso terapéutico , Diltiazem/sangre , Diltiazem/uso terapéutico , Monitoreo de Drogas/métodos , Humanos , Inmunosupresores/farmacocinética , Inmunosupresores/uso terapéutico , Persona de Mediana Edad , Vasodilatadores/uso terapéuticoRESUMEN
BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor type 1 blockers (ARB) are frequently prescribed for renal transplant patients. The main reasons for their use are that their antihypertensive and antifibrogenic effects may prevent chronic renal allograft dysfunction, potentially improving transplant survival. Furthermore, ACE and ARB have been used to reduce the hematocrit in patients with posttransplant erythrocytosis. We evaluated the effects of the ARB valsartan on the evolution of hematocrit in stable renal transplant patients treated with cyclosporine (CsA), azathioprine (Aza), and prednisone. PATIENTS AND METHODS: Twenty-six stable renal transplant patients treated with valsartan 80 mg/d orally were followed for 6 months. Evaluations were performed prior to as well as at 3 and 6 months following the initiation of valsartan. RESULTS: The hematocrit levels decreased significantly at 3 months (46.1 +/- 7.3 vs 39.9 +/- 5.8 ; P < .0001) in patients with a normal hematocrit, namely a level over 38%, with no further reduction at 6 months. In recipients with an hematocrit less than 38%, there was no significant reduction, either at 3 or 6 months follow-up. Valsartan was well tolerated without significant side effects. CONCLUSION: We postulate that inhibition of the proerythropoietic effects of angiotensin II and/or the reduction in hypoxia within the renal tubulointerstitium as well as the vasodilator effects on the efferent arterioles, represent possible mechanisms for the reduction and stabilization of the hematocrit in stable renal transplant patients.
Asunto(s)
Antihipertensivos/uso terapéutico , Hematócrito , Trasplante de Riñón/fisiología , Tetrazoles/uso terapéutico , Valina/análogos & derivados , Adulto , Anciano , Presión Sanguínea/efectos de los fármacos , Creatinina/sangre , Quimioterapia Combinada , Femenino , Humanos , Inmunosupresores/uso terapéutico , Trasplante de Riñón/inmunología , Masculino , Persona de Mediana Edad , Potasio/sangre , Valina/uso terapéutico , ValsartánRESUMEN
The ability of snake venoms to increase vascular permeability and to induce oedema through the release of pharmacologically active substances is well known. We have studied the oedema and vascular permeability induced by Bothrops lanceolatus venom in male Swiss white mice. Paw oedema was induced by the subplantar injection of B. lanceolatus venom (125-1000 ng/paw) and was quantified as the increase in paw weight. Changes in vascular permeability were assessed by measuring the amount of Evans blue dye extravasation. The oedema and the increase in vascular permeability were maximal within 2 h and had resolved after 24 h. The administration of the vasodilator iloprost (20 ng/paw) immediately after B. lanceolatus venom potentiated the oedema and the increase in vascular permeability by approximately four-fold. Pretreating the mice with indomethacin, dexamethasone, NDGA or BW A4C inhibited the venom-induced oedema and the increase in vascular permeability. In contrast, histamine, serotonin and PAF-acether antagonists (mepyramine, cyproheptadine and WEB 2086, respectively) were ineffective. Histological examination showed that B. lanceolatus venom (250 ng and 500 ng/paw) caused thickening of the inner dermal layers which was accompanied by extensive intercellular spaces indicative of oedema. In addition, there was a marked infiltration of inflammatory cells, particularly neutrophils, into the underlying muscle layer. The latter, however, remained morphologically unaffected during the 3 h of observation. Venom doses larger than 500 ng/paw produced intense haemorrhage. These results indicate that B. lanceolatus venom induces oedema and increases vascular permeability in the mouse hind paw. The principal mediators of this inflammatory response are cyclooxygenase and lipoxygenase products.
Asunto(s)
Permeabilidad Capilar , Venenos de Crotálidos/toxicidad , Edema/etiología , Animales , Antiinflamatorios/farmacología , Ácido Araquidónico/metabolismo , Azepinas/farmacología , Edema/patología , Masculino , Ratones , Triazoles/farmacologíaRESUMEN
PURPOSE: Neutrophils are implicated in the physiopathologic alterations of hemorrhagic cystitis (HC). Thus, we decided to test the antiinflammatory activity of glucose-mannose binding lectins extracted from D. violacea and D. guianensis seeds, which showed an inhibitory effect upon neutrophil migration in a model of rat peritonitis based on HC experimentally induced by cyclophosphamide (CYP). MATERIALS AND METHODS: Mice were treated with mesna (40 mg./kg., i.p.), lectins (1 and 10 mg./kg., i.v.) and 0.1 M of alpha-D-methyl-mannoside (alpha-CH3) or alpha-D-galactose (alpha-D-gal). The HC was induced by CYP (200 mg./kg., i.p.). The results were evaluated 12 hours after HC induction, based on the following parameters: vesical edema measurements, macroscopic and microscopic analysis of the bladders (Gray's analysis). The vesical edema was quantified either by the increase in bladder wet weight or by the determination of vesical vascular permeability (Evans' blue leakage). RESULTS: CYP-induced vesical edema was prevented by mesna and lectin treatment. The lectin effects were dose-dependent, and at the highest dose were similar to that achieved by mesna treatment. alpha-CH3 selectively reversed the lectin inhibitory effect. Histopathological analysis corroborated these findings and showed an intense reduction of leukocyte infiltration and tissue damage by lectin treatment. The bladders from the mesna-treated group showed a nearly normal histological pattern. However, differently from this group, none of the lectins abolished CYP-induced hemorrhage. CONCLUSIONS: The glucose-mannose binding lectins showed strong antiinflammatory activity in the mouse model of HC induced by CYP. As lectins mainly affected leukocyte vesical infiltration, we suggest a competitive blockage of glucosylated (mannose-glucose) selectin binding sites by lectins.
Asunto(s)
Antineoplásicos Alquilantes/efectos adversos , Ciclofosfamida/efectos adversos , Cistitis/inducido químicamente , Cistitis/prevención & control , Lectinas/uso terapéutico , Animales , Movimiento Celular/efectos de los fármacos , Cistitis/patología , Hemorragia/inducido químicamente , Hemorragia/prevención & control , Lectinas/farmacología , Masculino , Ratones , Neutrófilos/efectos de los fármacosRESUMEN
The natural physiological ligands for selectins are oligosaccharides found in glycoprotein or glycolipid molecules in cell membranes. In order to study the role of sugar residues in the in vivo lectin anti-inflammatory effect, we tested three leguminous lectins with different carbohydrate binding affinities in the peritonitis and paw oedema models induced by carrageenin in rats. L. sericeus lectin was more anti-inflammatory than D. virgata lectin, the effects being reversed by their specific binding sugars (N-acetylglucosamine and alpha-methylmannoside, respectively). However, V. macrocarpa, a galactose-specific lectin, was not anti-inflammatory. The proposed anti-inflammatory activity of lectins could be due to a blockage of neutrophil-selectin carbohydrate ligands. Thus, according to the present data, we suggest an important role for N-acetylglucosamine residue as the major ligand for selectins on rat neutrophil membranes.
Asunto(s)
Quimiotaxis de Leucocito/fisiología , Fabaceae , Lectinas/farmacología , Neutrófilos/fisiología , Plantas Medicinales , Selectinas/fisiología , Acetilglucosamina/análisis , Análisis de Varianza , Animales , Carragenina/toxicidad , Quimiotaxis de Leucocito/efectos de los fármacos , Edema/inducido químicamente , Edema/fisiopatología , Escherichia coli , Cinética , Lipopolisacáridos/toxicidad , Masculino , Neutrófilos/efectos de los fármacos , Peritonitis/inducido químicamente , Peritonitis/fisiopatología , Lectinas de Plantas , Ratas , Ratas Wistar , Selectinas/análisis , Selectinas/químicaRESUMEN
El objetivo de ese estudio fue evaluar y comparar la aparición de efectos adversos agudos luego de la infusión de metotrexato (MTX), citostático incluido en alas dosis en 2 diferentes protocolos (2g. vs. 5g/m2 por ciclo), utilizados durante la fase M del tratamiento de las leucemias linfoblásticas agudas (LLA) en el paciente pediátrico. Sesenta y seis pacientes que recibieron 264 ciclos de quimioterapia con altas dosis de MTX, fueron estudiados entre enero de 1995 y febrero de 1997. Todos ellos tenían el diagnóstico de LLA de riesgo estándar e intermedio, estaban en remisión completa y habián recibido anteriormente el protocolo I. Se anlizaron 2 tratamiento: el gurpo A) 132 ciclos con MTX a razón de 2g/m2/ciclo (n=32); grupo B 136 cilos con MTX a razón de 5g/m2/ciclo (n=34). Todos los pacientes recibieron 4 infusiones de MTX (1/10 de la dosis en 30´ y 9/10 de la dosis en el resto de las 24 hs.), con hidratación a 3000 ml/m2/día y alcalinización urinaria, en forma bimensual, junto a una punción lumbar con mediación intratecal (Profilaxis para evitar compromiso del sistema nervioso central) y 6-mercaptopurina oral diariamente durante el ciclo. No se observaron diferencias estadísticas significativas en relación a toxicidad hematológica severa: en 42 cukis (32.81 por ciento) en el grupo A y 44 cilcos (32.35 por ciento) en el grupo B; z=0.042: p=0.967. Sin embargo, la aparición de mucositis moderada y severa y valores elevados de las enzimas hepáticas se observaron con mayor frecuencia en el grupo B, mostrando una diferencia estadísticamente significativa. En nuestro estudio, no se observaron valores anormales de creatinina sérica. No hubo impacto sobre variaciones en el peso corporal en ambos protocolos. Concluimos que la dosis de MTX no influyó sobre la aparición de toxicidad hematológica, pero si sobre la aparición de efectos adversos en el tracto gastrointestinal y la función hepática.
Asunto(s)
Niño , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Metotrexato/efectos adversos , Metotrexato/uso terapéutico , Pruebas de Toxicidad AgudaRESUMEN
In the present study, histopathological analysis of rat mesentery was used to quantify the effect of two anti-inflammatory agents, dexamethasone (Dex) and pertussis toxin (Ptx), on leukocyte migration. The intravenous injection of Dex (1 mg/kg) and Ptx (1,200 ng) 1 h prior to the intraperitoneal injection of the inflammatory stimuli lipopolysaccharide (LPS) or formyl-methionyl-leucyl-phenylalanine (fMLP) significantly reduced the neutrophil diapedesis (LPS: Ptx = 0.86 ñ 0.19 and Dex = 0.35 ñ 0.13 vs saline (S) = 2.85 ñ 0.59; fMLP: Ptx = 0.43 ñ 0.09 and Dex 0.01 ñ 0.01 vs S = 1.08 ñ 0.15 neutrophil diapedesis/field) and infiltration (LPS: Ptx = 6.29 ñ 1.4 and Dex = 3.06 ñ 0.76 vs S = 15.94 ñ 3.97; fMLP: Ptx = 3.85 ñ 0.56 and Dex = 0.40 ñ 0.16 vs S = 7.15 ñ 1.17 neutrophils/field) induced by the two agonists in the rat mesentery. The inhibitory effect of Dex and Ptx was clearly visible in the fields nearest the venule (up to 200 µm), demonstrating that these anti-inflammatory agents act preferentially in the transmigration of neutrophils from the vascular lumen into the interstitial space, but not in cell movement in response to a haptotactic gradient. The mesentery of rats pretreated with Dex showed a decreased number of neutrophils within the venules (LPS: Dex = 1.50 ñ 0.38 vs S = 4.20 ñ 1.01; fMLP: Dex = 0.25 ñ 0.11 vs S = 2.20 ñ 0.34 neutrophils in the lumen/field), suggesting that this inhibitor may be acting at a step that precedes neutrophil arrival in the inflamed tissue. In contrast to that observed with Dex treatment, the number of neutrophils found in mesenteric venules was significantly elevated in animals pretreated with Ptx (LPS: Ptx = 9.85 ñ 2.25 vs S = 4.20 ñ 1.01; fMLP: Ptx = 4.66 ñ 1.24 vs S = 2.20 ñ 0.34 neutrophils in the lumen/field). This discrepancy shows that Ptx and Dex act via different mechanisms and suggests that Ptx prevents locomotion of neutrophils from the vascular lumen to the interstitial space. In conclusion, the method described here is useful for quantifying the inflammatory and anti-inflammatory effect of different substances. The advantage of this histopathological approach is that it provides additional information about the steps involved in leucocyte migration.
Asunto(s)
Animales , Masculino , Ratas , Antiinflamatorios/farmacología , Movimiento Celular/efectos de los fármacos , Dexametasona/farmacología , Mesenterio/patología , Neutrófilos/efectos de los fármacos , Toxina del Pertussis/farmacología , Escherichia coli , Inflamación/inducido químicamente , Recuento de Leucocitos , Lipopolisacáridos/efectos adversos , Venas Mesentéricas , N-Formilmetionina Leucil-Fenilalanina/efectos adversos , Ratas WistarRESUMEN
Clostridium difficile toxin A is associated with enterocolitis in animals and humans. However, the mechanisms of its secretory and damaging effects are not totally understood. In this work, we examined the intestinal secretion of electrolytes and water caused by supernatants from macrophages stimulated with toxin A in rabbit ileal mucosa mounted in Ussing chambers. We also investigated the mechanism by which the intestinal secretory factor (ISF) is released from stimulated macrophages. Supernatants from macrophages stimulated with toxin A caused potent intestinal secretion (change in short-circuit current [DeltaIsc], 76 microA x cm-2; P < 0.01). The release of the ISF was pertussis toxin sensitive (reduction, 61%; P < 0.01) and was also reduced (P < 0.05) by a protein synthesis inhibitor (67%), protease inhibitors (57%), a phospholipase A2 inhibitor (54%), a cyclo-oxygenase inhibitor (62%), a dual cyclo- and lipoxygenase inhibitor (48%), a platelet-activating factor (PAF) receptor antagonist (55%), and tumor necrosis factor alpha (TNF-alpha) synthesis inhibitors (48%). However, this release was not inhibited by a lipo-oxygenase inhibitor. Monoclonal anti-interleukin 1beta (IL-1beta) but not anti-IL-1alpha antibody blocked (72%; P < 0.01) the secretory action of the ISF, as did recombinant human IL-1 receptor antagonist (80%; P < 0.01). High levels of IL-1beta (3,476 pg/ml) were detected by an enzyme-linked immunosorbent assay in the above supernatants. Furthermore, the addition of IL-1beta to the serosal side caused a potent secretory effect (DeltaIsc, 80 microA x cm-2; P < 0.01). These results show that macrophages stimulated with toxin A release an ISF capable of provoking intestinal secretion. The regulation of this factor is dependent upon the activation of the G protein. In addition, prostaglandins, PAF, and TNF-alpha are involved in the release of the ISF. We conclude that IL-1beta is probably the ISF released by macrophages in response to toxin A.
Asunto(s)
Toxinas Bacterianas , Enterotoxinas/farmacología , Íleon/inmunología , Factores Inmunológicos/metabolismo , Interleucina-1/metabolismo , Macrófagos/inmunología , Animales , Femenino , Proteínas de Unión al GTP/metabolismo , Masculino , Modelos Inmunológicos , Factor de Activación Plaquetaria/inmunología , Conejos , Ratas , Transducción de Señal , Factor de Necrosis Tumoral alfa/metabolismo , Equilibrio Hidroelectrolítico/efectos de los fármacosRESUMEN
In the present study, histopathological analysis of rat mesentery was used to quantify the effect of two anti-inflammatory agents, dexamethasone (Dex) and pertussis toxin (Ptx), on leukocyte migration. The intravenous injection of Dex (1 mg/kg) and Ptx (1,200 ng) 1 h prior to the intraperitoneal injection of the inflammatory stimuli lipopolysaccharide (LPS) or formyl-methionyl-leucyl-phenylalanine (fMLP) significantly reduced the neutrophil diapedesis (LPS: Ptx = 0.86 +/- 0.19 and Dex = 0.35 +/- 0.13 vs saline (S) = 2.85 +/- 0.59; fMLP: Ptx = 0.43 +/- 0.09 and Dex 0.01 +/- 0.01 vs S = 1.08 +/- 0.15 neutrophil diapedesis/field) and infiltration (LPS: Ptx = 6.29 +/- 1.4 and Dex = 3.06 +/- 0.76 vs S = 15.94 +/- 3.97; fMLP: Ptx = 3.85 +/- 0.56 and Dex = 0.40 +/- 0.16 vs S = 7.15 +/- 1.17 neutrophils/field) induced by the two agonists in the rat mesentery. The inhibitory effect of Dex and Ptx was clearly visible in the fields nearest the venule (up to 200 microns), demonstrating that these anti-inflammatory agents act preferentially in the transmigration of neutrophils from the vascular lumen into the interstitial space, but not in cell movement in response to a haptotactic gradient. The mesentery of rats pretreated with Dex showed a decreased number of neutrophils within the venules (LPS: Dex = 1.50 +/- 0.38 vs S = 4.20 +/- 1.01; fMLP: Dex = 0.25 +/- 0.11 vs S = 2.20 +/- 0.34 neutrophils in the lumen/field), suggesting that this inhibitor may be acting at a step that precedes neutrophil arrival in the inflamed tissue. In contrast to that observed with Dex treatment, the number of neutrophils found in mesenteric venules was significantly elevated in animals pretreated with Ptx (LPS: Ptx = 9.85 +/- 2.25 vs S = 4.20 +/- 1.01; fMLP: Ptx = 4.66 +/- 1.24 vs S = 2.20 +/- 0.34 neutrophils in the lumen/field). This discrepancy shows that Ptx and Dex act via different mechanisms and suggests that Ptx prevents locomotion of neutrophils from the vascular lumen to the interstitial space. In conclusion, the method described here is useful for quantifying the inflammatory and anti-inflammatory effect of different substances. The advantage of this histopathological approach is that it provides additional information about the steps involved in leucocyte migration.
Asunto(s)
Antiinflamatorios/farmacología , Movimiento Celular/efectos de los fármacos , Dexametasona/farmacología , Mesenterio/patología , Neutrófilos/efectos de los fármacos , Toxina del Pertussis , Factores de Virulencia de Bordetella/farmacología , Animales , Escherichia coli , Inflamación/inducido químicamente , Recuento de Leucocitos , Lipopolisacáridos/efectos adversos , Masculino , Venas Mesentéricas , N-Formilmetionina Leucil-Fenilalanina/efectos adversos , Ratas , Ratas WistarRESUMEN
The anti-inflammatory activity of pertussis toxin (Ptx) was compared to that of a noncatalytic mutant of pertussis toxin (9K/129G; Ptxm), which contains two amino acid substitutions in the A protomer, by using a rat model of inflammation. The toxins were administered intravenously 1 h prior to the injection of inflammatory stimuli. Ptx, but not Ptxm, inhibited neutrophil migration into peritoneal cavities in response to formyl-methionyl-leucyl-phenylalanine and lipopolysaccharide. The inhibitory effect of Ptx on neutrophil migration could not be explained by the ability of the toxin to induce leukopenia or neutropenia. The increase in skin vascular permeability induced by leukotriene B4, a powerful neutrophil chemotactic agent, was also inhibited only by Ptx. On the other hand, the increase in skin vascular permeability induced by histamine was potentiated by both toxins. These data show that Ptx inhibits neutrophil-mediated inflammation in vivo and that this effect is dependent on the ADP-ribosyltransferase activity of the A protomer.
Asunto(s)
Antiinflamatorios/farmacología , Permeabilidad Capilar/efectos de los fármacos , Neutrófilos/efectos de los fármacos , Toxina del Pertussis , Factores de Virulencia de Bordetella/farmacología , Animales , Movimiento Celular/efectos de los fármacos , Proteínas de Unión al GTP/fisiología , Histamina/farmacología , Leucotrieno B4/farmacología , Lipopolisacáridos/farmacología , N-Formilmetionina Leucil-Fenilalanina/farmacología , Neutrófilos/fisiología , RatasRESUMEN
Selectins are essential for leukocyte recruitment in inflammation. Because of a lectin domain present in the selectin structure, we investigated the anti-inflammtory activity of six mannose-glucose binding lectins from brazilian beans: Dioclea guianensis-DguiL; D. grandiflora-DgL; Cratylia floribunda-CfL; D. violacea-D.vL; D. virgata-DvirL and Canavalia brasiliensis-ConBr. The lectins were injected intravenously (i.v.) into rats (0.1 and 1.0 mg/kg; 30 min before irritants) and its activities compared to E. coli endotoxin (LPS,30 mug/kg i.v.). Three lectins (DvL, CfL and DguiL), although less intense than LPS, inhibited the neutrophil migration induced by carrageenan (Cg, 300 mug) in a dose-dependent manner (0.1 and 1.0 mg/kg). DvL activity was reversed by 0.1 M alpha-D-methyl-mannoside (alpha-CH3), but not by 0.1 M alpha-D-galactose. The fMLP (44 ng)-induced neutrophil migration was also reduced by these lectins. Endotoxin contamination of lectin samples could be excluded since alpha-CH3 treatment reversed the DvL effect, but did not modify LPS inhibitory activity. Carrageenan (300 mug)-induced paw oedema was also reduced by LPS or lectin treatments. Conversely, none of the tested lectins inhibited dextran (Dex, 300 mug)-induced paw oedema, a classical leukocyte independent model, or zymosan (Zy, 1.0 mg)-induced peritonitis and paw oedema. LPS showed no effect upon Dex-induced paw oedema and barely reduced (25%) the oedematogenic effects of zymosan. As proposed for LPS, the lectin inhibitory activity was better observed on neutrophil-mediated inflammatory reactions. We speculate that the plant lectin antiinflammatory activity is probably due to a competitive blockage of a common leukocyte and/or endothelial selectin carbohydrate ligand.
RESUMEN
The effect of chronic N omega-nitro-L-arginine methyl ester (L-NAME) treatment on the in vivo eosinophil migration induced by bradykinin, platelet-activating factor (PAF), lipopolysaccharide and carrageenin has been investigated in the rat using the pleurisy model. The in vitro (microchemotaxis chamber) eosinophil migration induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP), PAF and zymosan-activated serum was also evaluated in the rat. The eosinophils were obtained from the peritoneal cavity of male Wistar rats and isolated on a discontinuous metrizamide gradient. Chronic inhibition of nitric oxide biosynthesis was achieved by adding L-NAME to the drinking water to give an intake of approximately 75 mumol/rat/day for 4 weeks. Rats treated chronically with L-NAME developed a significant level of hypertension (163 +/- 4.8 mmHg; P < 0.01) compared with animals which received either the same dose of the inactive enantiomer D-NAME (124 +/- 3.2 mmHg) or tap water alone (119 +/- 1.6 mmHg). The intrapleural injection of bradykinin (50 micrograms), PAF (1 microgram), lipopolysaccharide (0.25 microgram) and carrageenin (125 micrograms) into untreated rats in vivo induced a significant level of eosinophil migration by 24 h post-injection. This migration was markedly reduced in L-NAME-treated rats. Eosinophils obtained from untreated rats showed a significant level of migration in vitro in response to fMLP (5 X 10(-8) M), PAF (10(-8) M) and zymosan-activated serum (27 microliters). In contrast, the migration induced by these chemotactic agents was markedly reduced in cells isolated from animals treated chronically with L-NAME. L-Arginine (5.5 mM), but not D-arginine (5.5 mM), restored the ability of eosinophils from L-NAME-treated animals to migrate in response to fMLP. Our results indicate that nitric oxide plays a major role in the in vivo and ex vivo migration of eosinophils.
Asunto(s)
Quimiotaxis de Leucocito/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico/antagonistas & inhibidores , Animales , Bradiquinina/farmacología , Carragenina/farmacología , Recuento de Leucocitos , Lipopolisacáridos/farmacología , Masculino , N-Formilmetionina Leucil-Fenilalanina/farmacología , Óxido Nítrico/biosíntesis , Factor de Activación Plaquetaria/farmacología , Pleura/citología , Ratas , Ratas WistarRESUMEN
It is well established that exogenous RNA is incorporated into eukaryotic cells and is able to exert various biological responses. Little, however, is known about the effects of such RNA on macrophages. In this study, we demonstrate that RNA extracted from macrophages stimulated with Escherichia coli lipopolysaccharide (LPS), referred to as L-RNA, in contrast to RNA from non-stimulated macrophages (N-RNA), induces the release of a macrophage-derived neutrophil chemotactic factor (MNCF) and interleukin-8 (IL-8) from macrophage monolayers. The effect of L-RNA was dependent of the integrity of the polynucleotide chain and was not due to LPS contamination since its ability to induce MNCF and IL-8 release was strongly reduced by RNase but was not affected by DNase or polymyxin B. The poly A(+)L-RNA and poly A(-)L-RNA fractions were able to induce the release of MNCF and IL-8, indicating that the L-RNA could be acting at transcriptional and translational levels. The demonstration that actinomycin-D and cycloheximide inhibited the release of MNCF and IL-8 by L-RNA-stimulated macrophages confirms this assumption. Fractionation of the total L-RNA by centrifugation on a 5-20% sucrose gradient showed that the L-RNA which sediments in the 4-5S region of the gradient is the only fraction capable of inducing the release of MNCF from naive macrophages. We have previously shown that macrophage monolayers stimulated with interleukin-1 beta or LPS release a low molecular RNA which also sediments in the same 4-5S region. Taken together, these results support our proposal that resident macrophages, when activated by injurious stimuli, in addition to secreting cytokines, also release a low molecular weight (4-5S) RNA which may act on the surrounding macrophages to further stimulate the release of cytokines. This process would amplify the inflammatory response and would increase the mechanisms involved in the defense response or tissue injury.