Fire seasonality plays a limited role in the reproduction of Anacardium humile A. St.-Hil. in a tropical savanna.

Anthropogenic fires are an increasing threat to tropical savannas and their plant populations. In the Brazilian Cerrado, human-made fires at the end of the dry season are replacing natural fires at the beginning of the dry season. Critically, these late burns occur under more intense climate variables. Here, we aimed to understand the potential role of fire seasonality on individuals of Anacardium humile, a widespread Cerrado species of cultural and economic importance. We conducted two prescribed burnings, one at the beginning of the dry season (early burning) and one at the end of the dry season (late burning) when climate variables were remarkably different. We assessed the reproductive responses of A. humile individuals over 4 years and compared individuals from the fire treatments with those from an unburned area (control). The reproductive phenology of A. humile varied over time and was influenced by climate variables. The seasons of different burning had similar impacts on the reproductive phenology of A. humile, and this impact lasted for at least 4 years. While A. humile populations do not depend on fire for reproduction, they produced more flowers and fruits for up to 2 years with the fire treatments. We provide empirical evidence of the role of climate variables on the phenology of A. humile and demonstrate the importance of considering the role of time after fire events. The similar responses of A. humile to fire seasonality show that Cerrado fire management can be more complex than previously thought.

Effects of cytochalasin E on Paracoccidioides brasiliensis.

AIMS: To determine the effects of cytochalasin E, isolated from the extremophile fungus Aspergillus felis, on the cells of Paracoccidioides brasiliensis Pb18. METHODS AND RESULTS: Cytochalasin E showed a minimal inhibitory concentration of 3·6 µmol l-1 and minimum fungicidal concentration of 7·2 µmol l-1 on P. brasiliensis by in vitro microdilution and IC50 >964·0 µmol l-1 on murine macrophages. Its selectivity index (>263) indicated that this compound has selectivity for fungal cells. Morphological alterations were determined by optical and fluorescence microscopy, as well as scanning and transmission electron microscopy. Cytochalasin E affected P. brasiliensis bud-forming pseudohyphae, cell morphology, cell walls and cell membranes; caused the release of cellular material; and resulted in the production of reactive oxygen species. In murine macrophages, it affected cytoskeletal actin and inhibited phagocytosis. CONCLUSION: Cytochalasin E may be useful as an antifungal prototype against P. brasiliensis and in studies on phagocytosis. SIGNIFICANCE AND IMPACT OF THE STUDY: Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis (PCM). Treatment is prolonged to control the clinical manifestations and prevent relapse. The study on the effects of cytochalasin E in P. brasiliensis is important because it can be used as a prototype for new antifungal drugs and consequently, broadens the treatment options for PCM.

The diversity of mechanisms influenced by transthyretin in neurobiology: development, disease and endocrine disruption.

Transthyretin (TTR) is a protein that binds and distributes thyroid hormones (THs). TTR synthesised in the liver is secreted into the bloodstream and distributes THs around the body, whereas TTR synthesised in the choroid plexus is involved in movement of thyroxine from the blood into the cerebrospinal fluid and the distribution of THs in the brain. This is important because an adequate amount of TH is required for normal development of the brain. Nevertheless, there has been heated debate on the role of TTR synthesised by the choroid plexus during the past 20 years. We present both sides of the debate and how they can be reconciled by the discovery of TH transporters. New roles for TTR have been suggested, including the promotion of neuroregeneration, protection against neurodegeneration, and involvement in schizophrenia, behaviour, memory and learning. Recently, TTR synthesis was revealed in neurones and peripheral Schwann cells. Thus, the synthesis of TTR in the central nervous system (CNS) is more extensive than previously considered and bolsters the hypothesis that TTR may play wide roles in neurobiological function. Given the high conservation of TTR structure, function and tissue specificity and timing of gene expression, this implies that TTR has a fundamental role, during development and in the adult, across vertebrates. An alarming number of 'unnatural' chemicals can bind to TTR, thus potentially interfering with its functions in the brain. One role of TTR is delivery of THs throughout the CNS. Reduced TH availability during brain development results in a reduced IQ. The combination of the newly discovered sites of TTR synthesis in the CNS, the increasing number of neurological diseases being associated with TTR, the newly discovered functions of TTR and the awareness of the chemicals that can interfere with TTR biology render this a timely review on TTR in neurobiology.

Protective effects of the angiotensin type 1 receptor antagonist losartan in infection-induced and arthritis-associated alveolar bone loss.

BACKGROUND AND OBJECTIVE: The angiotensin type 1 (AT1) receptor has been implicated in the pathogenesis of inflammatory bone disorders. This study aimed to investigate the effect of an AT1 receptor antagonist in infection-induced and arthritis-associated alveolar bone loss in mice. MATERIAL AND METHODS: Mice were subjected to Aggregatibacter actinomycetemcomitans oral infection or antigen-induced arthritis and treated daily with 10 mg/kg of the prototype AT1 antagonist, losartan. Treatment was conducted for 30 d in the infectious condition and for 17 d and 11 d in the preventive or therapeutic regimens in the arthritic model, respectively. The mice were then killed, and the maxillae, serum and knee joints were collected for histomorphometric and immunoenzymatic assays. In vitro osteoclast assays were performed using RAW 264.7 cells stimulated with A. actinomycetemcomitans lipopolysacharide (LPS). RESULTS: Arthritis and A. actinomycetemcomitans infection triggered significant alveolar bone loss in mice and increased the levels of myeloperoxidase and of TRAP(+) osteoclasts in periodontal tissues. Losartan abolished such a phenotype, as well as the arthritis joint inflammation. Both arthritis and A. actinomycetemcomitans conditions were associated with the release of tumor necrosis factor alpha (TNF-α), interferon-gamma, interleukin-17 and chemokine (C-X-C motif) ligand 1 and an increased RANKL/osteoprotegerin ratio in periodontal tissues, but such expression decreased after losartan treatment, except for TNF-α. The therapeutic approach was as beneficial as the preventive one. In vitro, losartan prevented LPS-induced osteoclast differentiation and activity. CONCLUSION: The blockade of AT1 receptor exerts anti-inflammatory and anti-osteoclastic effects, thus protecting periodontal tissues in distinct pathophysiological conditions of alveolar bone loss.

The relevance of leukotrienes for bone resorption induced by mechanical loading.

5-Lipoxygenase (5-LO) metabolites are important pro-inflammatory lipid mediators. However, much still remains to be understood about the role of such mediators in bone remodeling. This study aimed to investigate the effect of 5-LO metabolites, LTB4 and CysLTs, in a model of mechanical loading-induced bone remodeling. Strain-induced tooth movement and consequently alveolar bone resorption/apposition was achieved by using a coil spring placed on molar and attached to incisors of C57BL6 (wild-type-WT), 5-LO deficient mice (5-LO(-/-)) and mice treated with 5-LO inhibitor (zileuton-ZN) or with antagonist of CysLTs receptor (montelukast-MT). The amount of bone resorption and the number of osteoclasts were determined morphometrically. The expression of inflammatory and bone remodeling markers in periodontium was analyzed by qPCR. Osteoclast differentiation and TNF-α production were evaluated in vitro using RAW 264.7 cells treated with LTB4 or LTD4. Bone resorption, TRAP(+) cells and expression of Tnfa, Il10 and Runx2 were significantly diminished in 5-LO(-/-), ZN- and MT-treated mice. The expression of Rank was also reduced in 5-LO(-/-) and MT-treated mice. Accordingly, LTB4 and LTD4 in association with RANKL promoted osteoclast differentiation and increased TNF-α release in vitro. These data demonstrate that the absence of 5-LO metabolites, LTB4 and CysLTs reduces osteoclast recruitment and differentiation, consequently diminishing bone resorption induced by mechanical loading. Thus, 5-LO might be a potential target for controlling bone resorption in physiological and pathological conditions.

MyD88 is essential for alveolar bone loss induced by Aggregatibacter actinomycetemcomitans lipopolysaccharide in mice.

Aggregatibacter actinomycetemcomitans is a Gram-negative bacteria highly associated with localized aggressive periodontitis. The recognition of microbial factors, such as lipopolysaccharide from A. actinomycetemcomitans ((Aa)LPS), in the oral environment is made mainly by surface receptors known as Toll-like receptors (TLR). TLR4 is the major LPS receptor. This interaction leads to the production of inflammatory cytokines by myeloid differentiation primary-response protein 88 (MyD88) -dependent and -independent pathways, which may involve the adaptor Toll/interleukin-1 receptor-domain-containing adaptor inducing interferon-ß (TRIF). The aim of this study was to assess the involvement of MyD88 in alveolar bone loss induced by (Aa)LPS in mice. C57BL6/J wild-type (WT) mice, MyD88, TRIF or TRIF/MyD88 knockout mice received 10 injections of Aa LPS strain FDC Y4 (5 µg in 3 µl), in the palatal gingival tissue of the right first molar, every 48 h. Phosphate-buffered saline was injected in the opposite side and used as control. Animals were sacrificed 24 h after the 10th injection and the maxillae were removed for macroscopic and biochemical analyses. The injections of Aa LPS induced significant alveolar bone loss in WT mice. In the absence of MyD88 or TRIF/MyD88 no bone loss induced by (Aa)LPS was observed. In contrast, responses in TRIF(-/-) mice were similar to those in WT mice. Diminished bone loss in the absence of MyD88 was associated with fewer TRAP-positive cells and increased expression of osteoblast markers, RUNX2 and osteopontin. There was also reduced tumor necrosis factor-α production in MyD88(-/-) mice. There was less osteoclast differentiation of hematopoietic bone marrow cells from MyD88(-/-) mice after (Aa)LPS stimulation. Hence, the signaling through MyD88 is pivotal for (Aa)LPS-induced osteoclast formation and alveolar bone loss.

Chronic sulforaphane oral treatment accentuates blood glucose impairment and may affect GLUT3 expression in the cerebral cortex and hypothalamus of rats fed with a highly palatable diet.

Obesity and insulin resistance are the key factors underlying the etiology of major health problems such as hypertension, diabetes and stroke. These important health issues lead researchers to investigate new approaches to prevent and treat obesity and insulin resistance. Good candidates are the phytochemical compounds that have been extensively studied in the field. Therefore, the aim of this study was to test whether sulforaphane (SFN, 1 mg kg⁻¹, 4 months treatment), a potent inducer of antioxidant enzymes present in cruciferous vegetables, had some beneficial effects on obesity and insulin resistance induced by a highly palatable (HP) diet in male Wistar rats. Glucose tolerance, serum and hepatic lipid levels, lipid profile, ALT, AST, urea and creatinine, GLUT1 and GLUT3 levels in the cerebral cortex, hippocampus and hypothalamus were analyzed. Glucose tolerance was lower in the HP diet groups, especially in the HP group treated with SFN. Except for the liver triacylglycerols, no differences were found in serum lipids, hepatic and kidney markers of the HP diet groups. Although expression of GLUT1 was similar between groups for all three brain structures analyzed, expression of GLUT3 in the cortex and hypothalamus had a tendency to decrease in the HP diet group treated with SFN. In conclusion, SFN at the specific dose was able to accentuate glucose intolerance and may affect GLUT3 expression in the cerebral cortex and hypothalamus.

Haematological response of curimbas Prochilodus lineatus, naturally infected with Neoechinorhynchus curemai.

This study evaluated the haematological response of curimbas Prochilodus lineatus, naturally infected with Neoechinorhynchus curemai (Acanthocephala: Neoechinorhynchidae). Thirty-seven fish were captured in October 2010 from the Mogi Guaçu River, Porto Ferreira, SP, Brazil. Infected fish presented increased mean corpuscular volume of erythrocytes, and lower thrombocyte and higher monocyte counts than uninfected fish.

Análise fitoquímica e atividade antimicobacteriana de extratos metanólicos de Jacaranda cuspidifolia Mart. (Bignoniaceae) / Phytochemical analysis and antimycobacterial activity of methanol extracts from Jacaranda cuspidifolia Mart. (Bignoniaceae)

Jacaranda cuspidifolia Mart., conhecida popularmente como "caroba", "jacarandá" ou "bolacheira", é utilizada medicinalmente para o tratamento da sífilis e da gonorréia. A atividade antimicobacteriana dessa espécie foi avaliada em ensaios in vitro com os extratos metanólicos das cascas e folhas, segundo o Método Analítico Alamar Blue (MABA). Os valores de concentração inibitória mínima para os extratos metanólicos das cascas e das folhas de J. cuspidifolia foram iguais a CIM = 250 μg mL-1 para ambos os extratos. A análise fitoquímica, por Cromatografia em Camada Delgada de gel de sílica, dos extratos metanólicos das cascas e folhas revelou a presença de taninos, flavonóides, terpenos, cumarinas e esteróides. A análise dos perfis dos extratos metanólicos por Cromatografia Líquida de Alta Eficiência de Fase Reversa registrou a presença de compostos fenólicos derivados do verbascosídeo sugerindo a provável responsabilidade pela ação antimicobacteriana.

Jacaranda cuspidifolia Mart., popularly known as "caroba", "jacaranda" or "bolacheira", is used as medicine for the treatment of syphilis and gonorrhea. The antimycobacterial activity of this species was assessed by means of in vitro assays with methanol extracts of barks and leaves according to the Microplate Alamar Blue Assay (MABA). The minimal inhibitory concentration values for methanol extracts of barks and leaves from J. cuspidifolia were MIC = 250 μg mL-1 for both extracts. Phytochemical analysis, by Thin Layer Chromatography on silica gel, of methanol extracts of barks and leaves revealed the presence of tannins, flavonoids, terpenes, cumarins and steroids. Analysis of the profiles of methanol extracts by High Performance Liquid Chromatography - Reversed Phase recorded the presence of phenolic compounds derivatives of verbascoside, suggesting their probable responsibility for the antimycobacterial action.

Frequency of thrombophilia determinant factors in patients with livedoid vasculopathy and treatment with anticoagulant drugs--a prospective study.

BACKGROUND: Livedoid vasculopathy (LV) is a chronic idiopathic disease characterized by painful purpuric macules on lower extremities. Its exact aetiology remains uncertain, but thrombotic and microcirculatory phenomena have been implicated as possible pathogenic factors. OBJECTIVES: To assess prospectively the frequency of thrombophilia and to verify the effectiveness of anticoagulant therapy among LV patients. METHODS: Thirty-four LV patients were tested for prothrombin time, activated partial thromboplastin time, antithrombin activity, protein C and S activity, anticardiolipin antibodies, lupus anticoagulant, prothrombin gene mutation, factor V Leiden mutation, methylenetetrahydrofolate reductase mutation, plasma homocysteine and fibrinogen. Thirteen of these patients were treated with anticoagulant drugs (either warfarin or heparin). RESULTS: Of 34 patients, 18 (52%) presented laboratory abnormalities of procoagulant conditions. Positive treatment response to anticoagulant therapy was observed in 11 patients. Improvement of pain was obtained in 1-3 weeks, an average of 1.8 week. Complete healing of the lesions was observed in about 2.3 months. Remission was sustained even after treatment interruption and lasted an average 7.8 months. No severe adverse effects were noticed. CONCLUSION: The authors suggest all patients with diagnosis of LV to be investigated for thrombophilic status. Anticoagulant drugs were well tolerated and seemed to be effective in treating not only LV symptoms but also its ulcerations.

sTNFR-1 is an early inflammatory marker in community versus institutionalized elderly women.

OBJECTIVE AND DESIGN: To evaluate plasma sTNFR-1 and IL-6 levels and correlate with hand grip in the institutionalized and community living Brazilian elderly. MATERIAL: A convenience sample of 110 elderly women (71.17 + or - 7.44 years) was selected. Plasma sTNFR-1 and IL-6 levels were measured by ELISA. For the measurement of hand grip, a JAMAR dynamometer was used. RESULTS: Plasma concentrations of inflammatory markers were significantly higher in institutionalized elderly (sTNFR-1: 479 + or - 22 pg/mL; IL-6: 6.3 + or - 0.8 pg/mL) than in community-dwelling elderly (sTNFR-1: 329 + or - 24 pg/mL; IL-6: 2.5 + or - 0.4 pg/mL; P < 0.0001). Institutionalized elderly had reduced hand grip (15 + or - 0.8 Kgf) in comparison to community dwelling elderly (23 + or - 0.6 Kgf; P < 0.05). When individuals were subdivided in age groups, sTNFR-1 was higher in community dwelling versus institutionalized elderly in the 60-70 age range. CONCLUSIONS: Our results demonstrate that being institutionalized has an impact on levels of inflammatory markers.

Commensal microbiota is fundamental for the development of inflammatory pain.

The ability of an individual to sense pain is fundamental for its capacity to adapt to its environment and to avoid damage. The sensation of pain can be enhanced by acute or chronic inflammation. In the present study, we have investigated whether inflammatory pain, as measured by hypernociceptive responses, was modified in the absence of the microbiota. To this end, we evaluated mechanical nociceptive responses induced by a range of inflammatory stimuli in germ-free and conventional mice. Our experiments show that inflammatory hypernociception induced by carrageenan, lipopolysaccharide, TNF-alpha, IL-1beta, and the chemokine CXCL1 was reduced in germ-free mice. In contrast, hypernociception induced by prostaglandins and dopamine was similar in germ-free or conventional mice. Reduction of hypernociception induced by carrageenan was associated with reduced tissue inflammation and could be reversed by reposition of the microbiota or systemic administration of lipopolysaccharide. Significantly, decreased hypernociception in germ-free mice was accompanied by enhanced IL-10 expression upon stimulation and could be reversed by treatment with an anti-IL-10 antibody. Therefore, these results show that contact with commensal microbiota is necessary for mice to develop inflammatory hypernociception. These findings implicate an important role of the interaction between the commensal microbiota and the host in favoring adaptation to environmental stresses, including those that cause pain.

Apoptotic mimicry: phosphatidylserine liposomes reduce inflammation through activation of peroxisome proliferator-activated receptors (PPARs) in vivo.

BACKGROUND AND PURPOSE: Recently, there has been much attention paid to understanding the molecular mechanisms underlying apoptosis and the functional consequences of apoptotic body clearance by phagocytes. In an attempt to investigate this latter aspect, the present study evaluated the anti-inflammatory effects of in vivo administration of phosphatidylserine (PS) liposomes, a well-characterised membrane component expressed during apoptosis. The participation of peroxisome proliferator-activated receptors (PPARs) in PS-mediated effects was also investigated. EXPERIMENTAL APPROACH: The anti-inflammatory effect of PS liposomes on the delayed phase of carrageenan mouse paw oedema was studied. PS liposomes were injected at different doses and times, after carrageenan. Hind paws were collected for evaluation of interleukin-1beta (IL-1beta) levels, myeloperoxidase (MPO) and N-acetyl-glucosaminidase (NAG) activities and Evans blue dye leakage. Participation of PPAR pathways was explored by using PPAR antagonists (BADGE and GW9662). KEY RESULTS: Administration of PS, but not phosphatidylcholine (PC), liposomes (20-200 mg kg(-1), i.p., 8 h after carrageenan) reduced the paw oedema in a dose-dependent manner. PS liposomes were effective even when administered 24 and 48 h after carrageenan, a time at which indomethacin (1 mg kg(-1), i.p.) had no significant effects. Carrageenan-induced Evans blue leakage and IL-1beta production was decreased in PS-treated paws. The PPAR antagonists (BADGE and GW9662) partially prevented the anti-inflammatory effects of PS administration. CONCLUSIONS AND IMPLICATIONS: PS liposomes have anti-inflammatory effects in vivo that are at least partly dependent on PPAR activation. Therapeutic strategies mimicking apoptosis may be useful for the treatment of inflammatory disorders.

Impaired host defense to Klebsiella pneumoniae infection in mice treated with the PDE4 inhibitor rolipram.

The increase in levels of cAMP in leukocytes by selective inhibitors of PDE4 may result in reduction of inflammation, and may be useful in the treatment of pulmonary inflammatory disorders in humans. Here, we have assessed whether oral treatment with the prototype PDE4 inhibitor, rolipram, interfered with the antibacterial host response following pulmonary infection of mice with Klebsiella pneumoniae. K. pneumoniae infection induced a marked increase in the recruitment of neutrophils to the lungs and the production of proinflammatory cytokines and chemokines, including tumor necrosis factor-alpha (TNF-alpha) and keratinocyte-derived chemokine (KC), in bronchoalveolar (BAL) fluid and lung tissue. There were also detectable amounts of interleukin-10 (IL-10) and significant lethality. Treatment with rolipram (3-30 mg kg-1) was associated with earlier lethality and significant inhibition of the TNF-alpha production. This was associated with enhanced production of IL-10 in lung tissue of rolipram-treated animals. Rolipram treatment did not affect KC expression and the recruitment of neutrophils in the lung tissue. Over 70% of neutrophils that migrated into the BAL fluid following K. pneumoniae infection ingested bacteria. Treatment with rolipram inhibited the percentage of neutrophils undergoing phagocytosis of K. pneumoniae in a dose-dependent manner. Maximal inhibition (62%) occurred at doses equal to or greater than 10 mg kg-1. Thus, treatment of mice with the PDE4 inhibitor rolipram is accompanied by earlier lethality, enhanced bacterial load and decreased capacity of the responding host to produce TNF-alpha and of neutrophils to phagocytose bacteria. It will be important to investigate whether the shown ability of PDE4 inhibitors to inhibit neutrophil phagocytosis and control experimental bacterial infection will translate into an inhibition of the ability of neutrophils to deal with infectious microorganisms in the clinical setting.

Role of the platelet-activating factor (PAF) receptor during pulmonary infection with gram negative bacteria.

The lipid mediator PAF plays an important role in the phagocytosis of particles, including bacteria, and consequent production of pro-inflammatory cytokines, such as TNF-alpha and IL-8. Using a PAF receptor antagonist (UK-74,505) and PAF receptor knock-out mice, we have investigated the relevance of PAF for the inflammatory changes and lethality after pulmonary infection with the gram-negative bacteria Klebsiella pneumoniae in mice. At an inoculum of 3 x 10(6) bacteria, there was marked pulmonary (bronchoalveolar lavage and lung) neutrophilia that started early (2.5 h after infection) and peaked at 48 h. All animals were dead by day 4 of infection. The chemokine KC and the pro-inflammatory cytokine TNF-alpha increased rapidly and persisted for 48 h in the lungs. Pretreatment with UK-74,505 (30 mg kg(-1) per day, p.o.) had no significant effects on the number of infiltrating neutrophils in BAL fluid or lung tissue, as assessed by histology and measuring myeloperoxidase, or on the concentrations of KC. In contrast, concentrations of TNF-alpha and the number of bacteria inside neutrophils were significantly diminished. In order to support a role for the PAF during K. pneumoniae infection, experiments were also carried out in PAFR-deficient mice. In the latter animals, lethality occurred earlier than in wild-type controls. This was associated with greater number of bacteria in lung tissue and diminished percentage of neutrophils containing bacteria in their cytoplasm. Our results suggest that PAF, acting on its receptor, plays a protective role during infection with K. pneumoniae in mice.

Effects of inhibition of PDE4 and TNF-alpha on local and remote injuries following ischaemia and reperfusion injury.

1. The effects of phosphodiesterase (PDE)4 and TNF-alpha inhibition were assessed on the local and remote injuries following intestinal ischaemia and reperfusion (I/R) injury in rats. 2. The PDE4 inhibitor rolipram dose-dependently (1 - 10 mg kg(-1)) suppressed the local (intestine) and remote (lung) increases in vascular permeability and neutrophil recruitment following mild I/R injury. SB207499 (ariflo), a structurally-distinct PDE4 inhibitor, also suppressed the injuries following mild I/R injury. 3. In a severe model of I/R injury, treatment with rolipram (10 mg kg(-1)) partially reversed the local and remote increases in vascular permeability, neutrophil recruitment, intestinal haemorrhage and intestinal LTB(4) concentrations. The anti-TNF-alpha anti-serum was more effective than rolipram at inhibiting local and remote injuries and prevented the lethality associated with severe I/R. 4. Rolipram and anti-TNF-alpha prevented the increase in the concentrations of TNF-alpha in the lung and intestine, but rolipram only partially inhibited the elevation of this cytokine in serum. Rolipram had little effect on the increases of IL-1 beta concentrations in lung and serum, whereas treatment with anti-TNF-alpha markedly increased the concentration of this cytokine. Concentrations of IL-10 rose significantly in the lung and serum and these increases were blocked by rolipram or anti-TNF-alpha. 5. The capacity of PDE4 inhibitors to block the recruitment of neutrophils into tissues, the production of LTB(4) and of the pro-inflammatory cytokines TNF-alpha, IL-1 beta and IL-6 appear to underlie their anti-inflammatory effects in our model of I/R injury. Overall, PDE4 inhibition was less effective than inhibition of TNF-alpha for protection against I/R injury.

Effects of a BLT receptor antagonist on local and remote reperfusion injuries after transient ischemia of the superior mesenteric artery in rats.

Reperfusion of ischemic vascular beds may lead to recruitment and activation of leukocytes, release of mediators of the inflammatory process and further injury to the affected vascular bed and to remote sites. Neutrophils appear to play a major role in the pathophysiology of reperfusion injury. Amongst inflammatory mediators shown to activate neutrophils and induce their recruitment in vivo, much interest has been placed on the role of leukotriene (LT)B(4). Here, we have assessed the effects of the BLT receptor antagonist (+)-1-(3S, 4R)-[3-(4-phenyl-benzyl)-4-hydroxy-chroman-7-yl]-cyclopentane carboxylic acid (CP 105,696) in a model of neutrophil-dependent ischemia and reperfusion injury in the rat. The superior mesenteric artery was isolated and ischemia was induced by its total occlusion for 30 min. After 30 min of reperfusion, injury was assessed by evaluating the extravasation of Evans blue, an index of vascular permeability, and the levels of myeloperoxidase, an index of neutrophil accumulation, in the intestine, mesentery and lung. The neutrophil-dependence of the local (intestine and mesentery) and remote (lung) injury was confirmed by using fucoidin, a selectin blocker, and WT-3, an anti-CD18 monoclonal antibody. Post-ischemic treatment with CP 105,696 dose-dependently inhibited vascular permeability and neutrophil accumulation in the intestine and mesentery. CP 105,696 also blocked the vascular permeability changes, but not neutrophil accumulation, in the lungs after reperfusion injury. Virtually identical results were obtained with another BLT receptor antagonist, 1-(5-ethyl-2-hydroxy-4-(6-methyl-6-(1H-tetrazol-5-yl)-heptoxy++ +)-phenyl )ethanone (LY255283). Our results suggest that post-ischemic treatment with BLT receptor antagonists may inhibit local and remote ischemia and reperfusion injury by blocking both the accumulation and/or activation of neutrophils.

The modulation of ecto-nucleotidase activities by glutamate in cultured cerebellar granule cells.

Several enzymes hydrolyze ATP, producing ADP which is hydrolyzed to AMP. Ecto-5'-nucleotidase produces adenosine from AMP. Glutamate (Glu) is an excitatory neurotransmitter and increases extracellular adenosine levels, which is considered an important inhibitory neuromodulator. Here we show that Glu activates ADP and AMP hydrolysis. NMDA and kainic acid (KA) also increased these enzymatic activities, but 1-aminocyclopentane-1S,3R-dicarboxylic acid (ACPD) had no effect. Dihydrokainate (DHK), an inhibitor of glutamate uptake, also blocked glutamate-evoked activation of ecto-nucleotidases, suggesting that this activation was also Glu transporters dependent. Therefore, we suggest that the Glu-evoked stimulation of ecto-nucleotidases might contribute to the increase of adenosine in extracellular space induced by Glu.

Effects of the PAF receptor antagonist UK74505 on local and remote reperfusion injuries following ischaemia of the superior mesenteric artery in the rat.

The effects of the long lasting and potent PAF receptor antagonist UK74505 were assessed on the local and remote injuries following ischaemia and reperfusion (I/R) of the superior mesenteric artery (SMA) in rats. In a severe model of ischaemia (120 min) and reperfusion (120) injury, in addition to the local and remote increases in vascular permeability and neutrophil accumulation, there was significant tissue haemorrhage, blood neutropenia, systemic hypotension and elevated local and systemic TNF-alpha levels. Post-ischaemic treatment with the selectin blocker fucoidin (10 mg kg(-1)) prevented neutrophil accumulation in tissue and, in consequence, all the local and systemic injuries following severe I/R. Treatment with an optimal dose of UK74505 (1 mg kg(-1)) also reversed local and remote neutrophil accumulation, increases in vascular permeability and intestinal haemorrhage. UK74505 partially inhibited blood neutropenia and reperfusion-induced hypotension. Interestingly, both fucoidin and UK74505 prevented the local, but not systemic, increases of TNF-alpha levels following severe I/R injury, demonstrating an important role of migrating cells for the local production of TNF-alpha. However, the results do not support a role for PAF as an intermediate molecule in the production of systemic TNF-alpha. The beneficial effects of UK74505 and other PAF receptor antagonists in models of I/R injury in animals and the safety of UK74505 use in man warrant further investigations of the use of this drug as preventive measure for I/R injury in humans.