Acute Toxicity of Aqueous Extract from Bredemeyera floribunda Root Bark in an Animal Model.

The medicinal plant Bredemeyera floribunda Willd. is used to treat cardiovascular disease, chronic fatigue, low libido, as well as increased diuresis. However, studies considering the toxicity of this plant are scarce. Develop an aqueous extract of B. floribunda considering traditional use and determine the average lethality (LD50), signs, and symptoms of toxicity. The B. floribunda extract was obtained by immersing the root bark in ultrapure water for 18 hours at 4°C, under constant stirring. The test extract was administered in a single dose of 2.000 mg/kg by gavage to rats. Signs and symptoms of toxicity were determined according to the Hippocratic screening test and compared with the control group. In addition, a necropsy was performed for macroscopic evaluation of the organs in the abdominal cavity. A powder was obtained from aqueous extracts that showed the same organoleptic characteristics and emulsification capacity as those presented by the fresh root when prepared according to popular tradition. The LD50 was greater than the test dose with three animals surviving. On the other hand, necropsy of dead rats showed necrosis and reduction in lung mass, in addition to the presence of foam and excessive distension of the stomach and intestines. The main symptoms of toxicity were anesthesia, ataxia, sedation, loss of muscle strength, and excessive drowsiness in the first 24 hours. There was no difference between the control and extract groups with regard to body mass, food, and water intake, as well as in macroscopy of the heart, liver, lungs, intestines, spleen, pancreas, and kidneys. The aqueous extract of the B. floribunda was considered nontoxic or of very low toxicity. However, it is capable of altering the activity of the central nervous system and causing disorders in the respiratory and digestive systems.

The potential of conventional and bulk-fill bioactive composites to inhibit the development of caries lesions around restorations.

PURPOSE: To determine caries inhibition potential of conventional and bulk-fill bioactive composites around restorations. METHODS: Enamel and dentin blocks were prepared using a diamond saw under water irrigation, finished (SiC, 600- and 800-grit) and polished (SiC 1,200, final polish= 0.2 µm). Blocks were then selected through enamel surface microhardness, and enamel and dentin standard cavities were restored (n=10/group) with conventional bioactive composite (Beautifil II, BTF), bulk-fill bioactive composite (Activa BioACTIVE, ACT), glass-ionomer cement (Ionofil Plus, ION), conventional composite (GrandioSO, GSO), and bulk-fill composite (Admira Fusion X-TRA, ADM). Afterwards, the blocks were subjected to pH cycling: 4 hours in demineralization and 20 hours in remineralization solutions for 7 days, before being cut in the middle. One half was used to calculate the carious lesion area (ΔS) using values obtained by cross-sectional microhardness (CSMH) testing. The other half was submitted to polarized light microscopy (PLM) and scanning electron microscopy (SEM). The % of internal gap formation (GAP) of restorations' replicas were analyzed under SEM. Data were analyzed by ANOVA and Tukey test (α= 5%). RESULTS: In terms of CSMH, ION group exhibited the lowest ΔS values, with no significant difference to ADM. The composites BTF and ACT were similar to each other (P< 0.05) and to their negative controls (GSO and ADM), respectively. ION showed lower caries formation under PLM, whereas the GSO group presented a greater demineralized area. ION presented the highest % of internal GAP formation. Bioactive composites (BTF and ACT) were similar to their corresponding conventional ones (GSO and ADM) in terms of GAP formation. CLINICAL SIGNIFICANCE: The glass-ionomer cement was more effective in inhibiting the formation of caries lesions around restorations. Because of the glass-ionomer cement's limited application in high load-bearing areas, the conventional bioactive composite would be a promising clinical choice.

Fundamental frequency related parameters in Brazilians with COVID-19.

This study compares fundamental frequency (fo) and fundamental frequency standard deviation (foSD) of COVID-19 patients with the same parameters in the speech of subjects without COVID-19, and verifies whether there is an effect of age and sex in the patient group. Both groups, subjects with and without COVID-19, are formed by Brazilian Portuguese speakers. Speech samples were obtained from 100 patients with mild to severe symptoms of COVID-19, and 100 healthy subjects. A single 31-syllable Portuguese sentence was used as the elicitation material for all subjects. The recordings were divided into four age groups. The acoustic measures were semi-automatically extracted and analyzed by a series of analyses of variance. Patients with COVID-19 present vocal differences in fo-related parameters when compared to healthy subjects, that is, patient voices presented higher fo and foSD with respect to control voices. In addition, for patient voices, there was an age and sex effect on fo SD values. Vocal parameters of women and elderly subjects showed more marked differences in fo-related parameters, indicating that patient voices are higher-pitched and have a higher variation of fo SD. Consequently, fo-related parameters may be tested as vocal biomarkers in the screening of respiratory insufficiency by voice analysis, in patients with severe symptoms of COVID-19.

Busca de inibidores de enzima conversora da angiotensina do veneno do escorpião Tityus serrulatus

Accidents by scorpion represent a problem for public health in Brazil, being the most recurrent among venomous animals. In the country, the main answerable species is the scorpion Tityus serrulatus, whose venom can induces serious clinical manifestation and cause death, mainly in children and elderly. Among the most serious pathological manifestations, poisoned humans can present cardiac and respiratory arrhythmias, cardiac insufficiency, shock and hypertension. In mammals, including humans, one of the major mechanisms involved in regulating blood pressure is the exacerbated activity of the angiotensin I converting enzyme (ACE I), and the inhibition of this enzyme has been widely explored by pharmacology related to the control of hypertension. Scorpion venom toxins with ability to promote an inhibition of this enzyme may elucidate the mechanisms involved in falling blood pressure in envenoming patients or to serve as models for the development of antihypertensive drugs. Recent works show that the venom of T. serrulatus is composed mainly of peptides and our studies identified peptide fractions capable of interacting with an ACE already described in the literature, indicating and contributing to the possible understanding of some mechanisms involving peptides and poisoning.

Acidentes causados por escorpiões representam um problema para a saúde pública no Brasil, sendo mais recorrentes entre os animais peçonhentos. No país, a principal espécie responsável por esse acontecimento é o escorpião Tityus serrulatus, cujo veneno pode induzir manifestações clínicas graves, até mesmo fatais, principalmente em crianças e idosos. Dentre as muitas manifestações clínicas mais graves apresentadas pelos acidentados está a arritmia cardíaca e respiratória, insuficiência cardíaca, choque e hipertensão arterial. Em humanos, um dos principais mecanismos envolvidos na regulação da pressão arterial está associada à atividade exacerbada da enzima conversora de angiotensina I (ECA I), sendo a inibição desta enzima muito explorada pela farmacologia relacionada ao controle da hipertensãoarterial. Toxinas do veneno capazes de proporcionarem a inibição desta enzima podem elucidar mecanismos envolvidos em quedas de pressão arterial de acidentados ou ainda servirem de modelo para o desenvolvimento de fármacos anti-hipertensivos. Trabalhos recentes mostram que o veneno do T. serrulatus é composto, principalmente, por peptídeos e nosso estudo encontrou frações peptídicas capazes de interagir com a ECA I, já descritas na literatura, nos indicando e contribuindo para o possível entendimento de alguns mecanismos envolvendo os peptídeos e o envenenamento.

BUSCA DE INIBIDORES DE ENZIMA CONVERSORA DA ANGIOTENSINA DO VENENO DO ESCORPIÃO Tityus serrulatus

Acidentes causados por escorpiões representam um problema para a saúde pública no Brasil, sendo mais recorrentes entre os animais peçonhentos. No país, a principal espécie responsável por esse acontecimento é o escorpião Tityus serrulatus, cujo veneno pode induzir manifestações clínicas graves, até mesmo fatais, principalmente em crianças e idosos. Dentre as muitas manifestações clínicas mais graves apresentadas pelos acidentados está a arritmia cardíaca e respiratória, insuficiência cardíaca, choque e hipertensão arterial. Em humanos, um dos principais mecanismos envolvidos na regulação da pressão arterial está associada à atividade exacerbada da enzima conversora de angiotensina I (ECA I), sendo a inibição desta enzima muito explorada pela farmacologia relacionada ao controle da hipertensãoarterial. Toxinas do veneno capazes de proporcionarem a inibição desta enzima podem elucidar mecanismos envolvidos em quedas de pressão arterial de acidentados ou ainda servirem de modelo para o desenvolvimento de fármacos anti-hipertensivos. Trabalhos recentes mostram que o veneno do T. serrulatus é composto, principalmente, por peptídeos e nosso estudo encontrou frações peptídicas capazes de interagir com a ECA I, já descritas na literatura, nos indicando e contribuindo para o possível entendimento de alguns mecanismos envolvendo os peptídeos e o envenenamento.

Depressão e ansiedade em mulheres com endometriose: uma revisão crítica da literatura / Depression and anxiety in women with endometriosis: an critical review

Essa revisão tem por objetivo apresentar os resultados dos estudos que avaliaram prevalência e/ou níveis de depressão e ansiedade nas mulheres com endometriose. Para isso, uma pesquisa bibliográfica foi realizada no PubMed, LILACS e Web of Science e foram selecionados para leitura 21 artigos. Destes,onze analisaram depressão e ansiedade simultaneamente, nove apenas depressão e um ansiedade. Foi observado que as pacientes com endometriose exibem níveis elevados de depressão e ansiedade,provavelmente devido aos quadros frequentes de dor, a infertilidade, ao atraso no diagnóstico e a recorrência da doença. Conclui-se que um acompanhamento psicológico deve ser oferecido a mulheres com endometriose sendo, portanto um componente essencial para o tratamento dessa condição ginecológica

Enzymatic hydrolysis of sweet lupin, chickpea, and lentil 11S globulins decreases their antigenic activity.

We investigated the effects of treatments with the enzymes pepsin and trypsin on the in vitro immunological reactivity of the major globulins found in the seeds of sweet lupin, chickpea, and lentil. Polyclonal major globulin-specific antiserum was obtained by immunization of rabbits with a solution of the 11S globulin of each legume. The globulins were hydrolyzed with pepsin and trypsin for 1, 5, 15, and 30 min. The native globulins and their hydrolysates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting to identify the polypeptide bands with antigenic activity, and the hypoantigenicity of the hydrolysates was analyzed by enzyme-linked immunosorbent assay. Our results show that enzymatic treatment of the major storage protein (11S globulin) of sweet lupin, chickpea, and lentil with pepsin or trypsin lead to the formation of large amounts of short peptides and free amino acids that do not allow antibody binding, resulting in a weakened immunoreactivity.

Pattern of macrophage activation in yersinia-resistant and yersinia-susceptible strains of mice.

Th1 cells, in cooperation with activated macrophages, are required to overcome Yersinia enterocolitica infection in mice. The pathway macrophages utilize to metabolize arginine can alter the outcome of inflammation in different ways. The objective of this study was to verify the pattern of macrophages activation in Y. enterocolitica infection of BALB/c (Yersinia-susceptible) and C57BL/6 (Yersinia-resistant) mice. Both strains of mice were infected with Y. enterocolitica O:8 WA 2707. Peritoneal macrophages and spleen cells were obtained on the 1st, 3rd and 5th day post-infection. The iNOS and the arginase activities were assayed in supernatants of macrophage cultures, by measuring their NO/citrulline and ornithine products, respectively. TGFbeta-1 production was also assayed. The Th1 and Th2 responses were evaluated in supernatants of lymphocyte cultures, by IFN-gamma and IL-4 production. Our results showed that in the early phase of Y. enterocolitica infection (1st and 3rd day), the macrophages from C57BL/6 mice produced higher levels of NO/citrulline and lower levels of ornithine than macrophages from BALB/c mice. The infection with Y. enterocolitica leads to an increase in the TGF-beta1 and IL-4 production by BALB/c mice and to an increase in the IFN-gamma levels produced by C57BL/6 mice. These results suggest that Y. enterocolitica infection leads to the modulation of M1 macrophages in C57Bl/6 mice, and M2 macrophages in BALB/c mice. The predominant macrophage population (M1 or M2) at the 1st and 3rd day of infection thus seems to be important in determining Y. enterocolitica susceptibility or resistance.

Kinetics of B cell response during Yersinia enterocolitica infection in resistant and susceptible strains of mice.

In this study we analyze the B-cell response in murine yersiniosis. To this end, we determined whether polyclonal activation of B-lymphocytes occurs during infection of susceptible (BALB/c) and resistant (C57BL/6) mice with Y. enterocolitica O:8 and compared the immunoglobulin (Ig) isotypes produced in response to the infection by the two strains. The number of splenic cells secreting nonspecific and specific immunoglobulins was determined by ELISPOT. The presence of anti-Yersinia antibodies in serum was detected by ELISA. In both strains, the number of specific Ig-secreting cells was relatively low. Polyclonal B-cell activation was observed in both strains of mice, and the greatest activation was observed in the BALB/c mice, mainly for IgG1- and IgG3- secreting cells. The C57BL/6 mice showed a predominance of IgG2a-secreting cells. The peak production of anti-Yersinia IgG antibodies in the sera of BALB/c mice was seen on the 28th day after infection. The greatest increase in IgM occurred on the 14th day. A progressive increase of specific IgG antibodies was observed in C57BL/6 mice up to the 28th day after infection while IgM increased on the 21st day after infection. The production of specific IgA antibodies was not detected in either BALB/c or C57BL/6 mice. We conclude that polyclonal activation of B lymphocytes occurs in both the Yersinia-resistant and Yersinia-susceptible mice and that the more intense activation of B lymphocytes observed in the susceptible BALB/c mice does not enhance their resistance to Y. enterocolitica infection.

Production of autoantibodies associated with polyclonal activation in Yersinia enterocolitica O: 8-infected mice.

Polyclonal lymphocyte stimulation is one of the immunomodulatory mechanisms induced by arthritogenic pathogens. In this study we examined the polyclonal activation potential of a virulent strain of Y. enterocolitica serotype O: 8 (WA 2707(+)) and its plasmidless isogenic pair (WA 2707(-)). SPF Swiss mice were infected intragastrically and spleen cells were obtained on days 7, 14, 21, 28, 35 and 42 after infection. The number of cells secreting nonspecific immunoglobulins of IgG, IgM and IgA isotypes was determined by the ELISPOT technique. The presence of serum-specific antibodies was investigated by ELISA and the presence of autoantibodies by dot-blot assay. Although the patterns of infection of the two bacterial strains were almost the same, only the animals infected with the virulent strain presented clinical anomalies. Neither arthritic nor inflammatory signs were observed in the joints of the infected animals. The greatest activation observed was that of the nonspecific IgM-secreting cells, and their peak of secretion occurred between the 28th and the 42nd day after infection, for both strains of Y. enterocolitica O: 8. Only the animals infected with the virulent strain (WA 2707(+)) produced IgG-specific antibodies in the serum, from the 28th day after infection. The serum of animals infected with either strain showed reactivity to all the autologous constituents tested, mainly on the 28th and 42nd day after infection. It was concluded that infection of mice with either the virulent strain of Y. enterocolitica O: 8 or with its plasmidless isogenic pair resulted in the polyclonal activation of the splenic B lymphocytes including some autoreactive clones.

Influence of Yersinia pseudotuberculosis outer proteins (Yops) on interleukin-12, tumor necrosis factor alpha and nitric oxide production by peritoneal macrophages.

An essential key to pathogenicity in Yersinia is the presence of a 70 kb plasmid (pYV) which encodes a type-III secretion system and several virulence outer proteins whose main function is to enable the bacteria to survive in the host. Thus, a specific immune response is needed in which cytokines are engaged. The aim of this study was to assess the influence of Yersinia outer proteins (Yops) released by Yersinia pseudotuberculosis on the production of the proinflammatory cytokines, interleukin-12 (IL-12), and tumor necrosis factor alpha (TNF-alpha), and nitric oxide (NO) by murine peritoneal macrophages. To this end, female Swiss mice were infected intravenously with wild-type Y. pseudotuberculosis or with mutant strains unable to secrete specific Yops (YopE, YopH, YopJ, YopM, and YpkA). On the 7th, 14th, 21st, and 28th days after infection, the animals were sacrificed and the cytokines and NO were assayed in the peritoneal macrophages culture supernatants. A fall in NO production was observed during the course of infection with all the strains tested, though during the infection with the strains that did not secrete YopE and YopH, the suppression occurred later. There was, in general, an unchanged or sometimes increased production of TNF-alpha between the 7th and the 21st day after infection, compared to the control group, followed by an abrupt decrease on the last day of infection. The IL-12 production was also suppressed during the infection, with most of the strains tested, except with those that did not secrete YopJ and YopE. The results suggest that Yops may suppress IL-12, TNF-alpha, and NO production and that the most important proteins involved in this suppression are YopE and YopH.

TNF-alpha, H2O2 and NO response of peritoneal macrophages to Yersinia enterocolitica O:3 derivatives.

In this study, the effect of Yersinia derivatives on nitric oxide (NO), hydrogen peroxide (H2O2) and tumor necrosis factor-alpha (TNF-alpha) production by murine peritoneal macrophages was investigated. Addition of lipopolysaccharide (LPS) to the macrophage culture resulted in NO production that was dose dependent. On the other hand, bacterial cellular extract (CE) and Yersinia outer proteins (Yops) had no effect on NO production. The possible inhibitory effect of Yops on macrophage cultures stimulated with LPS was investigated. Yops partially inhibited NO production (67.4%) when compared with aminoguanidine. The effects of Yersinia derivatives on H2O2 production by macrophages were similar to those on NO production. LPS was the only derivative that stimulated H2O2 release in a dose-dependent manner. All Yersinia derivatives provoked the production of TNF-alpha, but LPS had the strongest effect, as observed for NO production. CE and Yops stimulated TNF-alpha production to a lesser extent than LPS. The results indicate the possibility that in vivo Yops may aid the evasion of the bacteria from the host defense mechanism by impairing the secretion of NO by macrophages.

Yersinia enterocolitica O:3 isolated from patients with or without reactive arthritis induces polyclonal activation of B cells and autoantibody production in vivo.

The mechanisms by which arthritis-provoking pathogens such as Yersinia enterocolitica interact with the human immune system to produce inflammatory synovitis are not well known. One of the immunomodulating mechanisms used against these pathogens is the polyclonal activation of lymphocytes. In this study, we investigated the extent of the B-lymphocyte activation induced in mice by a strain of Y. enterocolitica O:3 (FCF 526) isolated from a patient with arthritis, and compared it with two other strains, a virulent one (FCF 397[+]) isolated from a patient without arthritis and its plasmidless isogenic pair (FCF397[-]). Also we investigated the production of autoantibodies in mice infected with these different strains. SPF Swiss mice were infected intravenously with a suspension of Y. enterocolitica. Spleen cells were taken on days 7, 14, 21 and 28 after infection and the number of cells secreting nonspecific and specific antibodies of IgG1, IgG2a, IgG2b, IgG3, IgM and IgA isotypes were determined by the ELISPOT technique. The presence of autoantibodies in mouse serum was investigated by the dot-blot assay. The pattern of infection of the three bacterial strains were almost the same. We observed a general increase in the number of nonspecific Ig-secreting cells with all three strains, and the greatest increases observed were in the IgG2a and IgG3 isotypes. Only a small fraction of the immunoglobulins detected were antibacterial, suggesting that the rest resulted from polyclonal B cell activation. The strain isolated from the patient with arthritis (FCF526) induced the greatest production of autoantibodies, coinciding with the period in which the greatest activation of nonspecific B lymphocytes was seen. There were no signs of arthritis or inflammation in the joints of the infected animals. Based on our results, we were unable to determine whether there is an association between the arthritogenic capability of Y. enterocolitica and polyclonal activation of B cells.

Effects of Yersinia enterocolitica O:3 derivatives on B lymphocyte activation in vivo.

The potential sequelae of intestinal infection with Yersinia enterocolitica include reactive arthritis, erythema nodosum, Reiter's syndrome and other autoimmune diseases. The role of the immune response in the pathogenesis of these diseases has not been fully defined, but autoimmune manifestations may be a consequence of the increase in autoantibodies as a result of polyclonal B-cell activation induced by Yersinia. We investigated the effects of Y. enterocolitica O:3 derivatives on B lymphocyte activation in vivo. Groups of five specific pathogen free (SPF) Swiss mice were inoculated with bacterial cell extract, Yersinia outermembrane proteins (Yops) or lipopolysaccharide (LPS) obtained from Y. enterocolitica O:3 and their immunoglobulin-secreting spleen cells were detected by isotype-specific protein A plaque assay. The presence of specific anti-Yersinia antibodies and autoantibodies was determined in mouse sera by ELISA. In all experiments a marked increase in the number of secretory cells of different isotypes was observed as early as the third day after inoculation. IgG and IgM anti-Yersinia antibodies were detected in the sera of all inoculated mice, and autoantibodies against myosin in the sera of those inoculated with bacterial cell extract. The sera from animals stimulated with LPS reacted with myelin, actin and laminin, while the sera from mice inoculated with Yops reacted with myelin, thyroglobulin and cardiolipin. These results suggest that SPF Swiss mice inoculated with any one of the Y. enterocolitica derivatives tested exhibited polyclonal activation of B lymphocytes as a result of stimulation by various bacterial components and not only LPS stimulation.

Telangiectasia macularis eruptiva perstans: relato de caso

Os autores relatam o caso de uma paciente de 65 anos que há três referia telangiectasias e máculas eritematosas disseminadas pela região torácica anterior, abdômen e membros inferiores, associadas a prurido eventual sem sintomas sistêmicos. No exame histopatológico foram demonstrados ectasia vascular e mastócitos pelo azul de toluidina. Foi feito o diagnóstico de Telangiectasia macularis eruptiva perstans. Trata-se de forma rara de mastocitose, geralmente de difícil diagnóstico e refratária ao tratamento

Comparaçäo entre a capacidade ativadora policlonal de Yersinia enterocolitica O: 3 e outros ativadores / Comparison between the polyclonal activation capability of Yersinia enterocolitica O: 3 and others activators

Ativaçäo policlonal de linfócitos induzida por endotoxinas bacterianas e superantígenos pode contribuir para o desenvolvimento de auto-imunidade. O objetivo deste trabalho foi comparar a ativaçäo policlonal de linfócitos B provocada por Yersinia enterocolitica O: 3 com aquela provocada por LPS de E. coli e por hemácias de carneiro. Camundongos Swiss foram infectados por via intraperitoneal com 10µg de LPS de E. coli ou com uma suspensäo de hemácias de carneiro a 2,5 por cento. Um grupo de animais normais foi usado como controle. No quinto dia pós-inoculaçäo, cinco animais de cada grupo foram sacrificados e as células esplênicas secretoras de imunoglobulinas detectadas pelo teste de PFC-Proteína A isotipo específico. No grupo dos animais infectados com Y. enterocolítica O: 3, a maior ativaçäo ocorreu em relaçäo às células secretoras de IgM (13 vezes aumentadas em relaçäo aos animais controles), seguida por IgG2b e IgG1 (ambos nove vezes). No grupo inoculado com LPS de E. coli, a maior ativaçäo ocorreu com relaçäo às células secretoras de IgG1 (cinco vezes), e, no grupo inoculado com hemácias de carneiro, a maior ativaçäo ocorreu com relaçäo às células secretoras de IgG1 (16 vezes) e IgM (oito vezes). O perfil comparativo do número de PFC revelou que Y. enterocolitica O: 3 apresentou maior capacidade de estimular linfócitos B in vivo do que os outros ativadores.

Ativaçäo de linfócitos B das placas de Peyer de camundongos infectados por via gástrica com Yersinia enterocolitica O: 8 / Peyer's patches B lymphocyte activation of mice infected by gastric route with Yersinia enterocolitica O: 8

Foi realizada infecçäo experimental de camundongos Swiss, "SPF", com amostra virulenta de Y. enterocolitica O: 8, inoculada por via gástrica, com o objetivo de verificar a ativaçäo de células B presentes nas placas de Peyer dos animais e comparar com aquela provocada por uma amostra isogênica, curada do plasmídeo de virulência. Para tanto, foi determinada a cinética de células secretoras de imunoglobulinas inespecíficas e específicas dos diferentes isótipos (IgG, IgA e IgM), pela técnica de ELISPOT e pesquisada a presença de anticorpos específicos anti-Yersinia nos soros dos animais infectados, por meio de ELISA. Foi verificada uma ativaçäo das células secretoras de imunoglobulinas inespecíficas nas placas de Peyer. Para a amostra virulenta, a maior ativaçäo ocorreu no número de células secretoras de IgG, e o pico de secreçäo ocorreu no 35§ dia pós-infecçäo (aumento de 8,9 vezes em relaçäo aos animais controles). Nos animais infectados com a amostra avirulenta, a maior ativaçäo ocorreu para o isótipo IgA, no 21§ dia pós-infecçäo (aumento de 16,1 vezes). Näo foi possível a detecçäo de células secretoras de Igs específicas. Anticorpos específicos do isotipo IgG foram detectados apenas nos soros dos animais infectados com a amostra virulenta, a partir do 28§ dia pós-infecçäo. Conclui-se que ambas as amostras de Y. enterocolitica O: 8 provocaram ativaçäo policlonal de linfócitos B das placas de Peyer.