Clostridium difficile toxins or infection induce upregulation of adenosine receptors and IL-6 with early pro-inflammatory and late anti-inflammatory pattern.

Clostridium difficile causes intestinal inflammation, which increases adenosine. We compared the expression of adenosine receptors (AR) subtypes A1, A2A, A2B, and A3 in HCT-8, IEC-6 cells, and isolated intestinal epithelial cells, challenged or not with Clostridium difficile toxin A and B (TcdA and TcdB) or infection (CDI). In HCT-8, TcdB induced an early A2BR expression at 6 h and a late A2AR expression at 6 and 24 h. In addition, both TcdA and TcdB increased IL-6 expression at all time-points (peak at 6 h) and PSB603, an A2BR antagonist, decreased IL-6 expression and production. In isolated cecum epithelial cells, TcdA induced an early expression of A2BR at 2s and 6 h, followed by a late expression of A2AR at 6 and 24 h and of A1R at 24 h. In CDI, A2AR and A2BR expressions were increased at day 3, but not at day 7. ARs play a role in regulating inflammation during CDI by inducing an early pro-inflammatory and a late anti-inflammatory response. The timing of interventions with AR antagonist or agonists may be of relevance in treatment of CDI.

Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice

Apolipoprotein E (APOE=gene, apoE=protein) is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln) treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE-/-) and wild-type (APOE+/+) C57BL6J male and female mice (N=86) were given either Ala-Gln (100 mM) or phosphate buffered saline (PBS) by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU) challenge (450 mg/kg, via intraperitoneal injection). Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1) and B-cell lymphoma 2 (Bcl-2) intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001) in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05) were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE-/- mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE+/+ mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE-/--challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU challenge.

Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice.

Apolipoprotein E (APOE=gene, apoE=protein) is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln) treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE-/-) and wild-type (APOE+/+) C57BL6J male and female mice (N=86) were given either Ala-Gln (100 mM) or phosphate buffered saline (PBS) by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU) challenge (450 mg/kg, via intraperitoneal injection). Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1) and B-cell lymphoma 2 (Bcl-2) intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001) in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05) were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE-/- mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE+/+ mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE-/- -challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU challenge.

Is pannexin the pore associated with the P2X7 receptor?

The P2X7 receptor (P2X7R), an ATP-gated cation channel, is expressed predominantly in leukocytes. Activation of P2X7R has been implicated in the formation of a cytolytic pore (i.e., a large conductance channel) that allows the passage of molecules up to 900 Da in macrophages. At least two hypotheses have been presented to explain the conversion of a nonselective cation channel to a cytolytic pore. One hypothesis suggests that the pore is a separate molecular structure activated by P2X7R, and the second asserts that this is an intrinsic property of P2X7R (pore dilation). Based on connexin knockout and hemichannel antagonist studies, some groups have concluded that connexins and pannexins, the hemichannel-forming proteins in vertebrates, are fundamental components of the large conductance channel associated with P2X7R. Dye uptake and electrophysiology experiments were used to evaluate the efficacy and specificity of some hemichannel antagonists under conditions known to open the large conductance channel associated with P2X7R. Hemichannel antagonists and interference RNA (RNAi) targeting pannexin-1 did not affect P2X7R macroscopic currents [ATP, 1,570±189 pA; ATP+100 µM carbenoxolone (CBX), 1,498±100 pA; ATP+1 mM probenecid (Prob), 1,522±9 pA] or dye uptake in a FACS assay (ATP, 63±5%; ATP+100 µM CBX, 51.51±8.4%; ATP+1 mM Prob, 57.7±4.3%) in mouse macrophages. These findings strongly suggest that the high-permeability pore evident after prolonged P2X7R activation does not occur through connexin or pannexin hemichannels in murine macrophages. Another membrane protein may be involved in P2X7R pore formation.

Determination of diflubenzuron residues in milk and cattle tissues / Determinação de resíduos de diflubenzuron em leite e tecidos bovinos

Diflubenzuron (DFB) is used to control ectoparasitic infestation by inhibiting larvae development in the manure and feces of treated animals. It is also currently been used to control tick infestations. In this study, milk and tissues from cattle treated orally with DFB for a 77-120 day period with a commercial product containing the compound were analyzed for the presence of residues. DFB residues were determined by using extraction with acetonitrile, cleanup with C18 SPE and chromatographic analysis by HPLC with UV detection (254nm). DFB was not detected in any of the analysed samples (<0.006mg kg-1 for fat, <0.014mg kg-1 for muscle, <0.015mg kg-1 for kidney, <0.016mg kg-1 for liver and <0.0006mg kg-1 for milk). In this manner, the use of this compound, according to the manufacturer's suggested doses may result in cattle milk, liver, kidneys, fat and muscles being considered safe regarding the presence of DFB residues.

O diflubenzuron (DFB) é um inibidor de desenvolvimento de insetos que inibe a síntese de quitina com atividade ovicida e larvicida e está sendo utilizado na pecuária para o controle do carrapato. Leite e tecidos provenientes de bovinos tratados por um período de 77 a 120 dias com um produto comercial contendo DFB foram analisados quanto à presença de resíduos. Os resíduos de DFB foram determinados utilizando-se extração com acetonitrila, limpeza por SPE C18 e cromatografia líquida de alta eficiência com detecção por UV (254nm). DFB não foi detectado em nenhuma das amostras analisadas (<0.006mg kg-1 para gordura, <0,014mg kg-1 para músculo, <0,015mg kg-1 para rim, <0,016mg kg-1 para fígado e <0.0006mg kg-1 para leite). Dessa forma, a utilização do princípio ativo conforme recomendado pelo fabricante e em níveis suficientes para se obter o efeito larvicida desejado deve resultar em leite, fígado, rins, gordura e músculos que podem ser considerados seguros para o consumo em termos da presença DFB.

Alterações histopatológicas da glândula mamária e qualidade do leite de cabras naturalmente infectadas com o CAEV / Histopathological changes in the mammary gland and milk quality of goats naturally infected with CAEV

Avaliou-se a influência do vírus da CAE nas características físico-químicas de amostras de leite de 54 cabras, sem predileção racial, distribuindo-as em dois grupos: cabras positivas e negativas para o teste de imunodifusão em gel de agarose. As amostras de leite foram submetidas à análise ultrassônica para obtenção de parâmetros físico-químicos - gordura, extrato seco, proteínas, lactose e densidade; realização de microbiologia - bactérias mesófilas (UCF/mL). Foram coletadas amostras de tecido mamário para exame histopatológico e imunohistoquímica. Não houve diferença significativa das características avaliadas entre os dois grupos; no microbiológico, não houve relação direta da presença de mesófilas associada à infecção pelo CAEV. Na histopatologia, observaram-se áreas com infiltração celular de monócitos, polimorfonucleares, plasmócitos, fibrose, ausência de morfologia normal do parênquima mamário, denotando processo inflamatório crônico; e foi confirmada a presença do vírus na glândula pela imunohistoquímica. Os resultados não mostraram relação direta da incidência da CAE como fator negativo no desenvolvimento do rebanho.

Aiming to evaluate the influence of CAE viruses in the chemical and physical characteristics of milk, the samples were collected from 54 goats, without racial predilection, these were divided into two groups: goats positive and negative according results of test Agarose Gel Immunodiffusion. Milk samples were ultrasonic analyzed to obtain physicochemical parameters (fat, solids, protein, lactose and density); performance microbiology (mesophilic bacteria - CFU/mL) and mammary gland samples were collected for evaluation histopathology and immunohistochemistry. The results of physical-chemical analysis showed no significant difference between the milk samples of two groups. In the microbiological analysis showed the presence of aerobic mesophilic bacteria, but this change is not associated with the presence of CAEV infection. On histopathology, there were areas with infiltration of mononuclear-leukocyte and polymorph nuclear, plasma cells, fibrosis and absence of normal morphology of the mammary tissue, indicating a chronic inflammatory process; and confirmed the presence of virus, in the gland, by immunohistochemistry. The results showed no direct relationship between incidence of CAE in the herd as a negative factor for its development, however it is known that the disease in its chronic nature, causes reduction in the productivity of the herd.

Produção de antígeno e separação da proteína p28 por microfiltragem seriada para sorodiagnóstico da artrite encefalite caprina por ensaio imunoenzimático / Production of antigen and p28 protein separation by microfiltration serial for serodiagnosis of caprine arthritis encephalitis by enzyme immunoassay

Este estudo teve como objetivo produzir um antígeno (Ag) a partir de cultura de células de membrana sinovial caprina (MSC) infectadas com o vírus de artrite encefalite caprina (CAEV), pela técnica de microfiltração seriada, substituindo a ultracentrifugação em colchão de sacarose (UCCS) para utilização em ELISA indireto (ELISA-i). Amostras de 188 soros caprinos, que previamente foram testados pelo Western blot (WB) com Ag UCCS, foram submetidas à análise pelo ELISA-i com o novo antígeno produzido, que mostrou concordância de 92% em relação ao antígeno UCCS. A sensibilidade e a especificidade do ELISA em relação ao WB foram de 95,6% e 88,5%, respectivamente. A nova técnica, criada a partir de microfiltrações, mostrou-se efetiva e de baixo custo para o diagnóstico sorológico de anticorpos para CAEV em comparação ao antígeno ultracentrifugado, e constitui uma alternativa viável para produção de antígeno purificado de lentivírus de pequenos ruminantes.

This study aimed to produce an antigen (Ag) from the culture of goat synovial membrane cells (MSC) infected by CAEV through serial microfiltering technique replacing ultra ultracentrifugation in sacarosis Mattress (UCCS) for the indirect diagnosis ELISA tests (i ELISA). Samples of 188 sera from goats previously examined by Western Blot (WB) with Ag UCCS were submitted to analysis by i ELISA with new antigen produced, demonstrating an accordance of 92% in relation to UCCS antigen. The specificity and sensitivity relating to WB were of 95,65% and 88, 5% respectively. The new technique created from the microfiltering is effective and with low cost for the serological antibodies diagnosis of CAEV comparing to the ultracentrifuged one, presenting, therefore, as a viable alternative for purified antigen of lentivirus in small ruminants.

Clinical applicability of natural product(s)-containing mouthwashes as adjunctive treatment of biofilm-induced gingivitis: a systematic review / Aplicabilidade clínica de colutórios à base de produtos naturais como tratamento adjuvante da gengivite induzida por biofilme: uma revisão sistemática

Natural products have emerged as an effective and low-cost alternative for treating various diseases of the oral cavity. This study aimed to evaluate, through a systematic literature review, if there is scientific evidence ensuring the safe and effective use of natural product(s)-containing mouthwashes as adjunctive treatment of biofilm-induced gingivitis. Searches were conducted in the databases Medline, SciELO, LILACS and Cochrane Library, by using combinations of the key words gingivitis/natural products/phytotherapy/mouthwash, in English, Portuguese and Spanish. Studies published until September 2010 were considered. Four examiners analyzed independently: study design and phase, methodological quality (Jadad scale - JE), experimental product and its concentration, dosing interval and time of usage, as well as employed statistical analysis and clinical outcome of interest. From the 503 articles found, 08 were included in the final review as phase II, controlled, randomized and blind clinical trials, scoring 4 (25%) and 5 (75%) in JE. The main natural products assessed were: Azadirachta indica, Garcinia mangostana, Lippia sidoides, Salvadora persica and Sesamum indicum whose concentration, dosing interval, time of usage and adverse effects varied according to each study. The Plaque and Gingival Index were most employed, as well as α = 5% and paired t, Student's t, Wilcoxon and Mann-Whitney tests. A total of 62.5% and 50% of the products significantly reduced supragingival biofilm and gingivitis, respectively. Mouthwashes containing the essential oil from the leaves of L. sidoides (1%) and the extract from the leaves of A. indica (25%) can be indicated as adjunctive treatment of biofilm-induced gingivitis.

Os produtos naturais têm surgido como alternativa eficaz e de baixo custo para o tratamento de várias doenças da cavidade oral. Objetivou-se avaliar, a partir de revisão sistemática da literatura, se há evidências científicas garantindo a utilização segura e eficaz de antissépticos bucais contendo produto(s) natural(is) como tratamento adjuvante da gengivite induzida por biofilme. Foram realizadas buscas nas bases de dados Medline, SciELO, LILACS e Cochrane Library, através de combinações usando as palavras-chave gengivite/produtos naturais/ fitoterápicos/bochechos, em Inglês, Português e Espanhol. Consideraram-se os estudos publicados até setembro de 2010. Quatro examinadores analisaram separadamente: desenho e fase do estudo, qualidade metodológica (escala de Jadad - EJ), produto experimental e a concentração, intervalo de administração e tempo de uso, bem como a análise estatística empregada e os resultados clínicos de interesse. Foram encontrados 503 artigos dos quais 08 foram incluídos na revisão final como sendo ensaios clínicos fase II, controlados, randomizados e cegos, marcando 4 (25%) e 5 (75%) na EJ. Os principais produtos naturais avaliados foram Azadirachta indica, Garcinia mangostana, Lippia sidoides, Salvadora persica e Sesamum indicum, cuja concentração, intervalo de administração, tempo de uso, e efeitos adversos, variaram de acordo com cada estudo. Índice de placa e Índice Gengival foram os mais utilizados, bem como α=5% e testes t-pareado, t-Student, Wilcoxon e Mann-Whitney. 62,5% e 50% dos produtos reduziram significativamente a presença de bioflme supragengival e gengivite, respectivamente. Os colutórios contendo o óleo essencial das folhas de L. sidoides (1%) e o extrato das folhas de A. indica (25%) podem ser indicados como tratamento adjuvante da gengivite induzida por biofilme.

Prevalência de anticorpos contra Leptospira spp. em bovinos, caninos, equinos, ovinos e suínos do município de Jaguapitã, estado do Paraná, Brasil / Prevalence of antibodies against Leptospira spp. in cattle, dogs, horses, sheep and swine of Jaguapitã, state of Paraná, Brazil

O objetivo deste trabalho foi determinar a prevalência de anticorpos contra Leptospira spp. em bovinos, caninos, equinos, ovinos e suínos, oriundos de 40 propriedades localizadas na área rural do Município de Jaguapitã, Estado do Paraná. Foram colhidas amostras de sangue de 370 bovinos, 161 equinos, 70 ovinos, 230 suínos e 97 caninos. O número de animais testados em cada propriedade, assim como o número de propriedades, foi determinado utilizando-se o programa Epi-info versão 6. As amostras de soros obtidas foram submetidas à prova de soroaglutinação microscópica (SAM) com 22 sorovares de Leptospira spp. Das 40 propriedades rurais pesquisadas, 38 (95,00%) tiveram pelo menos um animal sororeagente na SAM e dos 928 animais estudados, 316 (34,08%) apresentaram títulos ? 100. A prevalência observada na espécie bovina foi de 42,43%, com 87,18% das propriedades apresentando pelo menos um animal sororeagente. As prevalências de animais e propriedades reagentes para as demais espécies foram, respectivamente, 48,44% e 87,18% para equinos; 38,57% e 100% para ovinos; 18,70% e 28,00% para suínos; 11,34% e 31,25% para cães. O sorovar mais provável encontrado em bovinos foi Hardjo, em equinos Castellonis e Sentot, em ovinos, suínos e cães Icterohaemorrhagiae. Os resultados obtidos neste trabalho demonstram que as cinco espécies animais estudadas na área rural do Município de Jaguapitã tiveram contato com vários sorovares de Leptospira spp. Além disso, os resultados sorológicos sugerem uma possível transmissão do micro-organismo entre espécies animais, provavelmente em decorrência da exposição às mesmas fontes de infecção entre os animais estudados.

The objective of this work was to determine the prevalence of antibodies against Leptospira spp. in cattle, dogs, horses, sheep and swine from 40 properties located in the rural area of Jaguapitã, state of Paraná, Brazil. Blood samples were taken from 370 cattle, 97 dogs, 161 horses, 70 sheep and 230 swine. The number of animals tested on each property, as well as the number of properties was determined using the program Epi-info version 6. Samples of serum were submitted to microscopic agglutination test (MAT) with 22 Leptospira spp. serovars. From the 40 rural properties investigated, 38 (95.00%) had at least one positive animal according to SAM, and from 928 studied animals, 316 (34.08%) presented titers ? 100. The prevalence observed in the bovine species was 42.43%, with 87.18% of the properties presenting at least one positive animal. The prevalence of animals and properties reactive for the other species were, respectively: 48.44% and 87.18% for horses; 38.57% and 100% for sheep; 18.70% and 28.00% for swine; 11.34% and 31.25% for dogs. The most frequent serovar in bovines was Hardjo, in horses Castellonis and Sentot, in sheep, swine and dogs Icterohaemorrhagiae. The results obtained in this study demonstrated that the 5 studied animal species in the rural area of Jaguapitã had contact with several Leptospira spp. serovars. Moreover, serological results suggest a possible transmission of Leptospira spp. between animal species, probably because of exposure to the same sources of infection among the animals studied.

Pharmacological properties of a pore induced by raising intracellular Ca2+.

Recent studies on the P2X(7) receptor in 2BH4 cells and peritoneal macrophages have demonstrated that the raise in intracellular Ca(2+) concentration induces a pore opening similar to P2X(7) receptor pore. Herein, we have investigated whether the pore activated by the elevation of intracellular Ca(2+) concentration is associated to P2X(7) receptor. Using patch clamp in cell attached, whole cell configuration, and dye uptake, we measured the pore opening in cell types that express the P2X(7) receptor (2BH4 cells and peritoneal macrophages) and in cells that do not express this receptor (HEK-293 and IT45-RI cells). In 2BH4 cells, the stimulation with ionomycin (5-10 microM) increased intracellular free Ca(2+) concentration and induced pore formation with conductance of 421 +/- 14 pS, half-time (t(1/2)) for ethidium bromide uptake of 118 +/- 17 s, and t(1/2) for Lucifer yellow of 122 +/- 11 s. P2X(7) receptor antagonists did not block these effects. Stimulation of HEK-293 and IT45-RI cells resulted in pore formation with properties similar to those found for 2BH4 cells. Connexin hemichannel inhibitors (carbenoxolone and heptanol) also did not inhibit the pore-induced effect following the increase in intracellular Ca(2+) concentration. However, 5-(N,N-hexamethylene)-amiloride, a P2X(7) receptor pore blocker, inhibited the induced pore. Moreover, intracellular signaling modulators, such as calmodulin, phospholipase C, mitogen-activated protein kinase, and cytoskeleton components were important for the pore formation. Additionally, we confirmed the results obtained for electrophysiology by using the flow cytometry, and we discarded the possibility of cellular death induced by raising intracellular Ca(2+) at the doses used by using lactate dehydrogenase release assay. In conclusion, increased concentration in intracellular Ca(+2) induces a novel membrane pore pharmacologically different from the P2X(7) associated pore and hemigap-junction pore.

Adaptação do threshold IMT para teste de resistencia dos musculos inspiratorios / Adaptation of ThresholdIMT for endurance test on inspiratory muscles

Para avalaicao da resistencia muscular inspirtoria atraves de dispositivos do tipo threshold loading estudos anteriores empregaram equipamentos artesanais e indisponiveis comercialmente. Objetivos: verificar a aplicabilidade e reprodutibilidade de um teste de resistencia muscular inspiratoria utilizando a adaptacao de um antigo modelo do THRESHOLD IMT (nao disponivel comercialmente) com ampla gama de pressoes, avalaindo sua resistencia intrinseca ao fluxo inspiratorio, sua caracteristica limiar pressorica e sua relativa independencia do fluxo aereo na geracao de pressao durante os testes. Metodos: um antigo modelo do THRESHOLD IMT foi aberto, retirado sua mola interna e adaptado seu embolo. Apos montagem vertical, um sistema de peso externo foi instalado como gerador de carga. Valvulas foram instaladas para evitar re-inalacao de gas carbonico. Essa adaptacao foi testada aplicando-se diversas razoes de fluxosem a presenca do embolo e de carga para avaliacao da resistencia intrinseca e aplicando-se diversas razoes de fluxo quando instaladas cargas de 10 ate 130 cmH2O para avaliar a real pressao de abertura da valvula e o comportamento pressorico em altas razoes de fluxo. Resultados: a resistencia media foi de 4,8+-0,7 cmH2O/L.s-1, mas teve seu valor aumentado proporcionalmente ao fluxo. A pressao real de abertura foi inferior ao valor esperado (p=0,002), condicao encontrada em outros estudos. O comportamento pressorico apos a abertura da valvula foi similar em todas as cargas: um aumento medio de 3,8+-2,0 cmH2O para cada 1,0 L/S de fluxo gerado. Conclusao: a adaptacao proposta do THRESHOLD IMT produziu um dispositivo barato e confiavel para emprego em testes de resistencia muscular inspiratoria

Estudo preliminar da atividade antiinflamatória de Bryophillum calycinum Salisb / Preliminar study of the anti-inflammatory activity of Bryophillum calycinum Salisb

Foram avaliados a toxicidade aguda (DL50) do Extrato Bruto Aquoso Liofilizado das folhas de Bryophillum calycinum Salisb. (EBALBc) e seu efeito antiinflamatório sobre o edema de pata de rato induzido por carragenina e dextrana. Com a dose de 500 mg/kg (p.o) inibiu o edema de pata induzido por dextrana de maneira significativa (p < 0.05, ANOVA, Teste de Student Newman-Keuls) nos tempos de 60 e 90 minutos, enquanto que somente a dose oral de 1 g/kg de EBALBc inibiu o edema de pata induzido por carragenina. Os resultados indicaram efeito anti-edematogênico do extrato quando testado sobre o edema de pata induzido por dextrana e carragenina, sugerindo, entretanto, maior especificidade de ação sobre o edema induzido por dextrana. Por via oral, com as doses de 0,1 a 8 g/kg o EBALBc, não desencadeou óbito, não sendo possível determinar a DL50.

The acute toxicity (LD50) and the anti-inflammatory effect of the crude freeze-dried aqueous extract of the leaves of Bryophillumcalycinum Salisb. (EBALBc) was evaluated, on the rat paw edema induced by carrageenin and dextran. The dose of 500 mg/kg (p.o) inhibited the paw edema induced by dextran in a significative manner (p < 0.05, ANOVA, Student Newman-Keuls test) 60 and 90 minutes, after stimulus while only the oral dose of 1 g/kg of EBALBc inhibited the paw edema induced by carrageenin. The results indicated an anti-edematogenic effect of the extract when tested on the paw edema induced by dextran and carrageenin, suggesting larger specificity of action on the edema induced by dextran. The EBALBc administered orally, in the doses of the 0.1 to 8 g/kg, it did not cause death, making impossible to determine the LD50.

A novel form of cellular communication among thymic epithelial cells: intercellular calcium wave propagation.

We here describe intercellular calcium waves as a novel form of cellular communication among thymic epithelial cells. We first characterized the mechanical induction of intercellular calcium waves in different thymic epithelial cell preparations: cortical 1-4C18 and medullary 3-10 thymic epithelial cell lines and primary cultures of thymic "nurse" cells. All thymic epithelial preparations responded with intercellular calcium wave propagation after mechanical stimulation. In general, the propagation efficacy of intercellular calcium waves in these cells was high, reaching 80-100% of the cells within a given confocal microscopic field, with a mean velocity of 6-10 microm/s and mean amplitude of 1.4- to 1.7-fold the basal calcium level. As evaluated by heptanol and suramin treatment, our results suggest the participation of both gap junctions and P2 receptors in the propagation of intercellular calcium waves in thymic nurse cells and the more prominent participation of gap junctions in thymic epithelial cell lines. Finally, in cocultures, the transmission of intercellular calcium wave was not observed between the mechanically stimulated thymic epithelial cell and adherent thymocytes, suggesting that intercellular calcium wave propagation is limited to thymic epithelial cells and does not affect the neighboring thymocytes. In conclusion, these data describe for the first time intercellular calcium waves in thymic epithelial cells and the participation of both gap junctions and P2 receptors in their propagation.

Characterization of P2 receptors in thymic epithelial cells.

The presence of P2 receptors was investigated in three distinct preparations of murine thymic epithelial cells (TEC): 2BH4 murine cell line, IT45-R1 rat cell line, and a primary murine cell derived from the Nurse cell lympho-epithelial complex. In all preparations, application of ATP to the extracellular milieu triggered intracellular calcium signals indicating the presence of P2 receptor(s) in these cells. After an initial peak of calcium concentration, a plateau phase that could last more than 10 min was frequently observed. Ion replacement and channel blockage experiments indicated that the initial peak was associated with the release of calcium from intracellular stores, while the plateau phase was associated with an influx from the extracellular medium. ATP and UTP induced similar calcium signals, suggesting the presence of P2Y2 receptors in all three cell types. The murine 2BH4 cells also expressed P2X7/P2Z receptor, since under exposure to millimolar concentrations of ATP, a continuous rise in intracellular calcium concentration was observed and their plasma membranes became permeabilized to the fluorescent dyes Lucifer yellow and ethidium bromide. In addition, this permeabilization phenomenon was blocked by the P2Z-specific antagonist, oxidized ATP. RT-PCR assays confirmed the presence of mRNAs for the P2Y2 molecule in all TEC, while mRNA for the P2X7 molecule was detected only in 2BH4 cells. Our data indicate that P2Y2 purinergic receptors are widely expressed by thymic epithelial cells, whereas the expression of the P2X7 receptor appears to be more restricted, raising the possibility that its expression is related only to a particular epithelial microenvironment within/the thymus.

Pharmacologic properties of P(2Z)/P2X(7 )receptor characterized in murine dendritic cells: role on the induction of apoptosis.

In the immune system, extracellular adenosine 5'-triphosphate (ATP) mediates a variety of effects mainly through activation of a particular receptor subtype, the pore-forming P(2Z)/P2X(7) purinoceptor. This purinergic receptor has been described chiefly in cells of hemopoietic origin such as T cells, thymocytes, monocytes, macrophages, and phagocytic cells of thymic reticulum. In this study, we characterized the P(2Z)/P2X(7) purinoceptor and the ATP-mediated apoptosis in murine spleen-derived dendritic cells (DCs). Dye uptake and apoptosis were evaluated by flow cytometry. ATP-treated DCs were permeable to different low-molecular-weight fluorescent probes such as ethidium bromide, YO-PRO 1, and lucifer yellow. Such an effect was dose-dependent (EC(50): 721 micromol/L); mediated by the fully anionic agonist (ATP(4-)); and specifically stimulated by ATP, BzATP, and ATPgammaS. Additionally, an ATP-induced increase in intracellular calcium was detected by microfluorometry. Furthermore, ATP treatment induced a significant increase in apoptotic DCs (64. 46% +/- 3.8%) when compared with untreated control cells (34% +/- 5. 8%), as ascertained by the TdT-mediated dUTP nick end labeling technique. Both ATP-induced DC permeabilization and apoptosis were inhibited by oxidized ATP, a P(2Z)/P2X(7)-specific antagonist. In conclusion, we characterized the expression of the P(2Z)/P2X(7) purinoceptor in murine spleen-derived DCs and described its role on the induction of apoptosis.

Gap junction modulation by extracellular signaling molecules: the thymus model.

Gap junctions are intercellular channels which connect adjacent cells and allow direct exchange of molecules of low molecular weight between them. Such a communication has been described as fundamental in many systems due to its importance in coordination, proliferation and differentiation. Recently, it has been shown that gap junctional intercellular communication (GJIC) can be modulated by several extracellular soluble factors such as classical hormones, neurotransmitters, interleukins, growth factors and some paracrine substances. Herein, we discuss some aspects of the general modulation of GJIC by extracellular messenger molecules and more particularly the regulation of such communication in the thymus gland. Additionally, we discuss recent data concerning the study of different neuropeptides and hormones in the modulation of GJIC in thymic epithelial cells. We also suggest that the thymus may be viewed as a model to study the modulation of gap junction communication by different extracellular messengers involved in non-classical circuits, since this organ is under bidirectional neuroimmunoendocrine control.

Gap junction modulation by extracellular signaling molecules: the thymus model

Gap junctions are intercellular channels which connect adjacent cells and allow direct exchange of molecules of low molecular weight between them. Such a communication has been described as fundamental in many systems due to its importance in coordination, proliferation and differentiation. Recently, it has been shown that gap junctional intercellular communication (GJIC) can be modulated by several extracellular soluble factors such as classical hormones, neurotransmitters, interleukins, growth factors and some paracrine substances. Herein, we discuss some aspects of the general modulation of GJIC by extracellular messenger molecules and more particularly the regulation of such communication in the thymus gland. Additionally, we discuss recent data concerning the study of different neuropeptides and hormones in the modulation of GJIC in thymic epithelial cells. We also suggest that the thymus may be viewed as a model to study the modulation of gap junction communication by different extracellular messengers involved in non-classical circuits, since this organ is under bidirectional neuroimmunoendocrine control

Extracellular ATP: a further modulator in neuroendocrine control of the thymus.

It is well established that the process of thymocyte differentiation and maturation occurs in the thymus, where cell-to-cell communication is essential for providing the messages to T-cell precursors. At least two pathways are important for such communication: one via membrane surface molecules and the other via soluble mediators such as cytokines and some hormones. Recently, the presence of receptors for extracellular ATP has been demonstrated on thymocytes and microenvironment cells, and putative functions for this molecule have been proposed. Herein we focus on the recent evidence which supports the view of extracellular ATP and some related nucleotides as novel intrathymic signal molecules. In addition, we discuss the possible physiological implications of such purinergic receptors for the physiology of the thymus.

Neuroendocrine control of the thymus.

Thymocytes undergo a complex process of differentiation, largely dependent on interactions with the thymic microenvironment, a tridimensional cellular network formed by epithelial cells, macrophages, dendritic cells, and fibroblasts. One key cellular interaction involves the TCR-CD3 complex expressed by thymocytes with MHC-peptide complexes present on microenvironmental cells. Additionally, thymic epithelial cells (TEC) interact with thymocytes via soluble polypeptides such as thymic hormones and interleukins, as well as through extracellular matrix (ECM) ligands and receptors. Such types of heterotypic interactions are under neuroendocrine control. For example, thymic endocrine function, represented by thymulin production, is up-regulated, both in vivo and in vitro, by thyroid and pituitary hormones, including prolactin and growth hormone. We also showed that these peptides enhance the expression of ECM ligands and receptors, as well as the degree of TEC-thymocyte adhesion. In addition, we studied the thymic nurse cell complex, used herein as an in vitro model for ECM-mediated intrathymic T-cell migration. We observed that T-cell migration is also hormonally regulated as ascertained by the thymocyte entrance into and exit from these lymphoepithelial complexes. Taken together these data clearly illustrate the concept that neuroendocrine circuits exert a pleiotropic control on thymus physiology. Lastly, the intrathymic production of classic hormones such as prolactin and growth hormone suggests that, in addition to endocrine circuits, paracrine and autocrine interactions mediated by these peptides and their respective receptors may exist in the thymus, thus influencing both lymphoid and microenvironmental compartments of the organ.

Are there functional gap junctions or junctional hemichannels in macrophages?

The existence of functional gap junctions in migratory cells of the immune system is a controversial issue. In this report, we have focused on one particular cell type, namely the macrophages, because connexin-43, a protein that forms gap junctions, has been described in peritoneal macrophages and a macrophage cell line (J774), by Northern and Western blot analysis. To test whether these cell types expressed functional gap junctions, we assayed dye coupling by intracellular injection of Lucifer Yellow. We observed that nonstimulated macrophages are not coupled among themselves and did not form functional gap junctions with an epithelial cell line, which expresses functional gap junctions formed by connexin-43. Dye coupling was also not detected between macrophages previously activated by lipopolysaccharide or interferon-gamma. We further examined the presence of functional coupling using the more sensitive technique of dual whole cell patch-clamp, and again, did not find electrical coupling between macrophages, consistent with the dye microinjection data. We also examined the possible presence of hemigap junction channels activated by extracellular adenosine triphosphate (ATP) using a dye uptake assay and the whole cell patch-clamp technique. Conditions expected to close gap junction hemichannels (exposure to octanol and low intracellular pH) did not decrease ATP-induced Lucifer Yellow uptake, whereas conditions expected to increase hemichannel opening either did not affect ATP permeabilization (dibutyryl adenosine monophosphate) or decreased it (zero extracellular CA+2). Finally, in experiments using resident macrophages derived from conexin-43 knockout mice, we observed ATP induced dye uptake. Our experimental data thus indicate that macrophages in vitro do not form functional gap junctions and that the permeability pathway activated by extracellular ATP is not formed by a hemigap junction channel.