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Background: Metabolic Syndrome is a set of disorders that characterized by the association of three or more risk factors, like the obesity central, dyslipidemia, borderline blood pressure, hyperglycemia, and the increase of triglycerides. However, these factors also can be associated with pathophysiology of frailty. Objectives: verifying whether the metabolic syndrome is associated to the positive frailty screening in the older people. Design: Cross-sectional study. Participants: 443 older people living in Rio Branco, Brazil. Setting: Data collection was carried out in two stages: a personal interview and blood collection. Measurements: The diagnosis of metabolic syndrome was based on the criteria of the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults. The frailty screening was performed using subjective questions validated in a previous study. Descriptive statistics and multinomial logistic regression were used for data analyses. Results: There was a predominance of female older people (69.07%), aged between 60 and 79 years (87.13%), with an income greater than or equal to one minimum wage (72.09%), no cognitive decline (75.94%) and depressive symptoms (63.31%), independent for BADL (86.46%) and dependent for IADL (51.69%). From the total sample, 56.88% of the older people were identified as frail, 34.09% pre-frail and 9.03% non frail. The prevalence of metabolic syndrome was 51.69%. After adjusting by the independent variables, an association between metabolic syndrome and pre-frailty was observed, and older people with metabolic syndrome were more likely to be prefrail (RRR=2.36; 95%CI=1.08-5.18). Conclusion: The metabolic syndrome was associated to the increase chance of screening for prefrailty in the older people evaluated, which reinforces the needy to establish preventive measures in relation to the metabolic syndrome to avoid frailty in the older people.
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The following article from International Endodontic Journal, 'Micro-computed tomography evaluation of apical transportation and centring ability of Reciproc and WaveOne systems in severely curved root canals' by D. A. de Meireles, T. C. C. A. de Brito, A. A. F. Marques, A. D. B. Garrido, L. F. R. Garcia & E. C. Sponchiado Jr, published online on 5 February 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor in Chief, Prof. Paul Dummer, and John Wiley & Sons Ltd. The retraction has been agreed due to the use of techniques for crucial measurements in canal shaping and a lack of clarity regarding the measuring methodology. The use of inadequate measuring methodologies makes the findings of the paper invalid.
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The pine processionary caterpillar, Thaumetopoea pityocampa, is considered an emerging pine pest in Mediterranean countries, with high medical relevance. In recent years, adverse reactions reports in humans following contact with T. pityocampa have been increasingly reported. Dogs living in pinewood areas are also frequently exposed to the caterpillar. This work consisted on a retrospective study of 41 cases of lepidopterism. All dogs presented drooling, dysphagia, submandibular lymphadenomegaly and clinical signs of pain. The animals were distributed in three groups, according to the time span from exposure to the caterpillar until presentation: up to 2 h (group 1), 2-5 h (group 2) and more than 5 h (group 3). All animals from groups 2 (n = 5) and 3 (n = 9), and eight dogs from group 1 (n = 27) developed lingual necrosis. Lepidopterism coursed through a predictable clinical pattern. The evolution was mainly dependent on the time span between exposure to the caterpillar and medical intervention, which should take place earlier than 2 h from exposure.
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Alérgenos/efectos adversos , Dermatitis Alérgica por Contacto/veterinaria , Enfermedades de los Perros/inmunología , Mariposas Nocturnas/inmunología , Urticaria/veterinaria , Animales , Trastornos de Deglución , Dermatitis Alérgica por Contacto/diagnóstico , Dermatitis Alérgica por Contacto/inmunología , Dermatitis Alérgica por Contacto/terapia , Enfermedades de los Perros/diagnóstico , Enfermedades de los Perros/terapia , Perros , Exposición a Riesgos Ambientales/efectos adversos , Humanos , Larva/inmunología , Necrosis/veterinaria , Dolor , Pinus , Estudios Retrospectivos , Sialorrea , Factores de Tiempo , Lengua/patología , Urticaria/diagnóstico , Urticaria/inmunología , Urticaria/terapia , ZoonosisRESUMEN
Canine leishmaniosis (CanL) caused by the protozoan parasite Leishmania infantum is a chronic systemic disease that is endemic in certain parts of the world. The domestic dog is the most important reservoir of L. infantum and is the main source of infection for other animals and for the human population. The aim of this study was to evaluate and compare the level of expression of genes encoding particular cytokines (interleukin [IL]-12, interferon [IFN]-γ, IL-2 and IL-4) in different tissues and organs of 53 adult dogs with or without clinical signs of leishmaniosis and after treatment for the disease. Asymptomatic dogs showed high expression of genes encoding IL-4 in blood leucocytes and of genes encoding IL-12 and IL-2 in lymph nodes. Blood leucocytes from symptomatic dogs had a mixed Th1 and Th2 cytokine gene expression profile, but lymph nodes from these animals had dominant IL-2 and IFN-γ gene expression, while bone marrow appeared to be unresponsive. The predominance of IL-4 gene expression in the blood of asymptomatic dogs may favour parasite replication, while the balance between Th1 and Th2 cytokine gene expression in the blood of symptomatic dogs may be important in reducing parasite replication and delaying the dissemination of Leishmania to other organs. The drugs used to treat CanL do not completely eliminate the parasite, so the high expression of the gene encoding IL-4 in blood leucocytes and the high expression of IL-12 and IL-4 mRNA in lymph nodes may reflect the persistence of residual Leishmania amastigotes. L. infantum appears able to regulate the host immune response in order to ensure its survival, but also to prevent the host from succumbing to infection. This guarantees its transmission and the completion of its life cycle.
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Enfermedades de los Perros/metabolismo , Interferón gamma/biosíntesis , Interleucinas/biosíntesis , Leishmania infantum , Leishmaniasis Visceral/veterinaria , Animales , Médula Ósea/metabolismo , Brasil , Enfermedades de los Perros/genética , Enfermedades de los Perros/inmunología , Perros , Femenino , Regulación de la Expresión Génica , Interacciones Huésped-Parásitos , Interferón gamma/genética , Interleucina-12/biosíntesis , Interleucina-12/genética , Interleucina-2/biosíntesis , Interleucina-2/genética , Interleucina-4/biosíntesis , Interleucina-4/genética , Interleucinas/genética , Leishmaniasis Visceral/genética , Leishmaniasis Visceral/inmunología , Leishmaniasis Visceral/metabolismo , Ganglios Linfáticos/metabolismo , Masculino , Portugal , ARN Mensajero/biosíntesis , Células TH1/metabolismo , Células Th2/metabolismo , Clima Tropical , Salud UrbanaRESUMEN
PURPOSE: To determine the frequency of N-acetyltransferase 2 (NAT2) polymorphisms, the NAT2 acetylation profile and its relation to the incidence of gastrointestinal adverse drug reactions (ADRs), anti-tuberculosis (TB) drug-induced hepatotoxicity, and the clinical risk factors for hepatotoxicity in a population from Brazil. METHODS: Two hundred and fifty-four Brazilian TB patients using isoniazid (INH), rifampicin (RMP), and pirazinamide (PZA) were tested in a prospective cohort study. NAT2 genotyping was performed by direct PCR sequencing. The association between gastrointestinal ADRs/hepatotoxicity and the NAT2 profile genotype was evaluated by univariate analysis and multiple logistic regression. RESULTS: Of the 254 patients analyzed, 69 (27.2%) were slow acetylators and 185 (72.8%) were fast acetylators. Sixty-five (25.6%) patients were human immunodeficiency virus (HIV)-positive. Thirty-three (13%) and 14 (5.5%) patients developed gastrointestinal ADR and hepatotoxicity, respectively. Of the 14 hepatotoxicity patients, nine (64.3%) were slow acetylators and five (35.7%) were fast acetylators. Sex, age, presence of hepatitis C virus, alcohol abuse, and baseline aminotransferases were not found to be risk factors for hepatotoxicity. However, logistic regression analysis revealed that slow acetylator status and the presence of HIV (p < 0.05) were independent risk factors for hepatotoxicity. CONCLUSIONS: Our findings show that HIV-positive patients that have the slow acetylation profile are significantly associated with a higher risk of developing hepatotoxicity due to anti-TB drugs.
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Antituberculosos/efectos adversos , Arilamina N-Acetiltransferasa/metabolismo , Hígado/efectos de los fármacos , Tuberculosis/tratamiento farmacológico , Acetilación , Arilamina N-Acetiltransferasa/genética , Secuencia de Bases , Brasil , Estudios de Cohortes , Cartilla de ADN , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido SimpleRESUMEN
An in situ hybridization (ISH) assay for the detection of leptospiral DNA in tissues was described and its diagnostic and pathogenetic usefulness in combination with immunohistochemistry (IHC) was evaluated in formalin-fixed, paraffin-embedded liver and kidney samples from human fatal cases of leptospirosis. IHC assays with anti-E-cadherin antibodies assessed the liver-plate disarray frequently observed in leptospirosis. Immunohistochemistry detected leptospiral antigen (LAg) in macrophages, both in human liver and kidney. In guinea pigs, in addition to these findings, staining on cell membranes of hepatocytes and, occasionally, in apical membrane of kidney tubular cells was demonstrated. Positive ISH signal was observed chiefly in the nuclei of human hepatocytes and in the cytoplasm and nuclei of liver cells of experimentally infected guinea pigs. Loss of E-cadherin membrane expression is associated with liver-plate disarray. These findings were discussed in the contention that, in leptospirosis, cell membrane damage might be important for the pathogenesis of the disease. Finally, it was suggested that both IHC and/or ISH might be used for both diagnostic and research purposes.
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ADN Bacteriano/aislamiento & purificación , Hibridación in Situ/métodos , Riñón/microbiología , Leptospirosis/diagnóstico , Leptospirosis/metabolismo , Hígado/microbiología , Adulto , Animales , Cadherinas/metabolismo , Membrana Celular/metabolismo , Membrana Celular/patología , Femenino , Cobayas , Humanos , Inmunohistoquímica , Riñón/metabolismo , Riñón/patología , Leptospirosis/patología , Hígado/metabolismo , Hígado/patología , Masculino , Persona de Mediana EdadRESUMEN
BACKGROUND: Chromoblastomycosis is a chronic, suppurative, granulomatous mycosis usually confined to skin and subcutaneous tissues. The host defense mechanisms in chromoblastomycosis have not been extensively investigated. The purpose of the present study was to determine the distribution and pathways of the fungal antigen(s) and the possible role of the different immunocompetent cells in antigen processing in skin lesions. METHODS: The distribution of Fonsecaea pedrosoi antigen(s) in human skin was studied in 18 biopsies from 14 patients with chromoblastomycosis. A purified polyclonal immune serum raised in rabbits against metabolic antigen(s) of F. pedrosoi was used to detect yeast antigen(s) by immunohistochemical procedures. Double immunolabeling was performed with yeast antigen(s) and Langerhans' cells [labeled with anti-S100 protein monoclonal antibody (MoAb)], yeast antigen(s) and factor XIIIa+ dermal dendrocytes (immunolabeled with anti-factor XIIIa polyclonal antibody), and yeast antigen(s) and macrophages (labeled with CD 68 monoclonal antibody). RESULTS: The F. pedrosoi antigen(s) accumulated in the skin macrophages and, in a few instances, in factor XIIIa+ dendrocytes and Langerhans' cells. CONCLUSIONS: The data obtained suggest that chiefly macrophages, also Langerhans' cells and factor XIIIa+ dermal dendrocytes, function as antigen-presenting cells in chromoblastomycosis.
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Antígenos Fúngicos , Ascomicetos/inmunología , Cromoblastomicosis/inmunología , Células de Langerhans/inmunología , Macrófagos/inmunología , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Antifúngicos , Antígenos Fúngicos/análisis , Antígenos Fúngicos/inmunología , Ascomicetos/aislamiento & purificación , Biopsia , Cromoblastomicosis/microbiología , Cromoblastomicosis/patología , Factor XIIIa/análisis , Factor XIIIa/inmunología , Femenino , Humanos , Células de Langerhans/microbiología , Células de Langerhans/patología , Macrófagos/microbiología , Macrófagos/patología , Masculino , Persona de Mediana Edad , Piel/químicaRESUMEN
OBJECTIVE: To analyse the morphological aspects of the extracellular matrix and microcirculation to clarify whether chronic Chagas' cardiopathy (CCC) is an accurate model to study the pathogenesis of idiopathic dilated cardiomyopathy (IDCM). DESIGN: Thick histological myocardial sections were prepared to analyse collagen, and microcirculation was examined during confocal laser and light microscopy. SETTING: The specimens were prepared at the pathology service of the Heart Institute of São Paulo, Brazil. PATIENTS: Nine control hearts, eight IDCM hearts, and 10 CCC hearts were studied after necropsy. MAIN OUTCOME MEASURES: The number of collagen struts per 100x field, the area of fibrosis (%), and the diameters of arterioles and capillaries were measured in each heart to establish outcome. RESULTS: A smaller number (mean (SD)) of collagen struts was seen in the hearts in the IDCM group (9.1 (4.1)) than in the control (22.4 (3.2)) (p < 0.05) or CCC (15.7 (7.4)) (p > 0.05) groups. Fibrosis was greater in the CCC hearts (13.8 (10.5)%) than in the IDCM hearts (5.9 (6.6)%) (p > 0.05). Major increases in arteriole (65.4 (9.9) microm) and capillary (9.9 (1.7) microm) diameters were seen in the CCC hearts but not in the IDCM hearts (arteriole diameter 40.3 (7.9) microm; capillary diameter 7.9 (1.3) microm). CONCLUSIONS: Hearts demonstrating CCC and IDCM present different extracellular and microvessel alterations. This suggests that distinct pathogenic mechanisms are responsible for each condition and that CCC is not an effective model to study IDCM.
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Cardiomiopatía Dilatada/patología , Cardiomiopatía Chagásica/patología , Vasos Coronarios/patología , Adolescente , Adulto , Anciano , Arteriolas/patología , Capilares/patología , Cardiomiopatía Dilatada/metabolismo , Cardiomiopatía Chagásica/metabolismo , Niño , Colágeno/análisis , Matriz Extracelular/patología , Femenino , Humanos , Masculino , Microscopía Confocal , Persona de Mediana EdadRESUMEN
In situ hybridization (ISH) was performed using oral biopsies from patients with paracoccidioidomycosis and guinea pig testes inoculated with a culture of Paracoccidioides brasiliensis isolated from soil, employing both a 14 base-pair specific oligoprobe (ACT CCC CCG TGG TC) and its complementary sequence. When combining ISH with the Gridley stain which detects fungal cell walls, about 2-3% of the fungal cells present in the tissues were labelled. When the complementary probe was used, labelling was higher, reaching the 3% level.
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Hibridación in Situ , Paracoccidioides/genética , Paracoccidioidomicosis/microbiología , Adulto , Animales , Cobayas , Humanos , Hibridación in Situ/métodos , Masculino , Persona de Mediana Edad , Paracoccidioidomicosis/patologíaRESUMEN
Adult worm antigen (AWA) and soluble egg antigen (SEA) were localized ultrastructurally by immunoelectron microscopy using two monoclonal antibodies in the glomeruli of hamsters infected with Schistosoma mansoni cercariae or injected with S. mansoni eggs. AWA was detected in all cercaria-infected groups from the 30th day on and was present mainly in cytoplasm of mesangial cells, mesangial matrix, and glomerular basement membrane, either as isolated gold particles or in small electron-dense deposits of probable immune origin. AWA was encountered also on the inner side of the glomerular basal membrane, close to endothelial cells, and in the foot processes of the glomerular epithelial cells. SEA was detected at similar sites, apparently in lesser amounts, in uninfected hamsters inoculated with S. mansoni eggs into the jugular vein. Schistosomal antigens are apparently processed mainly bymesangial cells which are considered to be critical in the pathogenesis of S. mansoni associated glomerulopathy. Mesangioproliferative glomerulonephritis, immunoglobulin (IgG and IgM), and C3 deposits were observed in hamsters in which AWA and SEA were visualized. During early phases of the infection and in hamsters in which granulomatous pneumonitis was induced by S. mansoni eggs, glomeruli were unchanged or showed a slight mesangial proliferation. Our findings suggests that egg antigens also contribute to the pathogenesis of experimental glomerulopathy in the hamster.
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Antígenos Helmínticos/análisis , Glomérulos Renales/inmunología , Schistosoma mansoni/inmunología , Esquistosomiasis mansoni/inmunología , Animales , Cricetinae , Técnica del Anticuerpo Fluorescente Directa , Glomérulos Renales/patología , Mesocricetus , Microscopía Inmunoelectrónica , Esquistosomiasis mansoni/patologíaRESUMEN
Colonization of the colon and rectum by intestinal spirochetes is detected for the first time in Brazil in 4 of 282 (1.41%) patients who had undergone sigmoidoscopy and/or colonoscopy with a histopathological diagnosis of chronic non specific-colitis. This frequency is probably underestimated, since surgically obtained specimens were not considered in the present study. Histopathological diagnosis was performed using routine stains like hematoxylin-eosin which showed the typical, of 3-microns thick hematoxyphilic fringe on the brush border of the surface epithelium, and by silver stains like the Warthin-Starry stain. Immunohistochemical procedures using two, polyclonal, primary antibodies, one against Treponema pallidum and the other against Leptospira interrogans serovar copenhageni serogroup Icterohaemorrhagiae cross-reacted with spirochetal antigen/s producing a marked contrast of the fringe over the colonic epithelium, preserving the spiral-shaped morphology of the parasite. In one case with marked diarrhea, immunohistochemistry detected spirochetal antigen/s within a cell in an intestinal crypt, thus demonstrating that the infection can be more widely disseminated than suspected using routine stains. Immunohistochemical procedures, thus, greatly facilitate the histological diagnosis of intestinal spirochetosis and may contribute to a better understanding of the pathogenesis of the disease. Transmission and scanning electron microscopy performed in one case showed that the spirochete closely resembled the species designated as Brachyspira aalborgi.
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Colon/ultraestructura , Enfermedades del Colon/patología , Recto/ultraestructura , Infecciones por Spirochaetales/diagnóstico , Spirochaetales/ultraestructura , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Biopsia , Brasil/epidemiología , Niño , Preescolar , Colon/microbiología , Enfermedades del Colon/microbiología , Femenino , Humanos , Inmunohistoquímica , Lactante , Mucosa Intestinal/microbiología , Mucosa Intestinal/ultraestructura , Masculino , Microscopía Electrónica , Microscopía Electrónica de Rastreo , Persona de Mediana Edad , Recto/microbiología , Infecciones por Spirochaetales/epidemiología , Infecciones por Spirochaetales/microbiologíaRESUMEN
Two sheep antisera, one of which raised against polysaccharide (Po) and other against protein (Pt) components of Schistosoma mansoni adult worms, were assessed by ELISA for their ability to detect circulating parasite antigens in patients with different clinical forms of chronic schistosomiasis mansoni. The former antiserum detected parasite antigens in liver granulomata and the latter in renal glomeruli from schistosomiasis patients and mice experimentally infected with S. mansoni. In general, the levels and/or positivity rate of circulating antigens and specific IgG antibodies were significantly higher in patients with hepatointestinal (HI) and hepatosplenic (HS) forms than in mild intestinal (I) forms. An association between Po antigens and clinical features of the disease was observed, as the level of these antigens was low (137 ng/ml) as well as the positivity rate (7.9%) in patients with I forms; values that were intermediate (593 ng/ml and 33.3%) in those with HI forms, and high (1.563 ng/ml and 50.0%) in more severe HS forms. The Pt antigens were detected in the studied clinical forms not differing statistically but, the positivity rate was significantly higher in HS forms comparatively to I forms. The antisera studied revealed distinct circulating antigen profiles, and the prognostic value of Po and Pt antigens was suggested.
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Proteínas del Helminto/inmunología , Polisacáridos/inmunología , Schistosoma mansoni/inmunología , Esquistosomiasis mansoni/sangre , Animales , Antígenos Helmínticos/análisis , Enfermedad Crónica , Humanos , Sueros Inmunes/inmunología , Inmunoglobulina G/análisis , Esquistosomiasis mansoni/tratamiento farmacológicoAsunto(s)
Granuloma/patología , Formación de Anticuerpos , Fibrosis , Granuloma/clasificación , Granuloma/inmunología , Humanos , Inmunoglobulina G/sangre , Linfocitos/inmunología , Macrófagos/patología , Necrosis , Paracoccidioidomicosis/inmunología , Paracoccidioidomicosis/patología , Esquistosomiasis mansoni/inmunología , Esquistosomiasis mansoni/patologíaRESUMEN
Trypanosoma cruzi parasites are only rarely identified in conventional histological sections of hearts from chronic chagasic patients. This finding suggests that T. cruzi plays no important direct role in the chronic myocarditis that accordingly has been considered mainly an autoimmune process. We reinvestigated this issue using a polyclonal anti-T. cruzi antibody serum to map immunohistochemically the T. cruzi antigen(s) in 9 different regions of 8 necropsy hearts and 24 septal fragments from 24 hearts from chronic chagasic patients. T. cruzi antigen(s) were identified in 7 (87%) of the 8 mapped hearts and in 14 (58%) of the 24 septal fragments. There was a statistically significant correlation between the presence of T. cruzi antigen(s) and moderate or severe inflammatory infiltrate (p = 0.005). When staining revealed amastigotes within intact myocardial fibers, there was no surrounding inflammatory infiltrate. However, when T. cruzi antigen(s) were found in macrophages either as amastigotes, diffusely in the macrophages cytoplasm, or free in the interstitium as round structures similar to amastigotes, there was a heavy inflammatory infiltrate. In the case in which no parasite was detected, a mild inflammatory infiltrate was present in the myocardium. Foci of fibrosis did not stain for T. cruzi antigen. These findings do not exclude a role of autoimmunity in chronic chagasic cardiopathy. However, the striking correlation between the presence of T. cruzi antigen(s) with the severity of site of the inflammatory infiltrate supports a direct role for the parasite in the perpetuation of myocardial inflammation in Chagas' disease. The destruction of microvessels and occasional endothelial cells with parasitism among dense inflammatory infiltrate favors the concept that microcirculatory injury, induced by T. cruzi, also contributes to the lesions of chronic Chagas' disease.
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In order to investigate the morphogenes of experimental leptospirosis by morphologic and immunohistologic methods, 24 guinea-pigs were inoculated intraperitoneally with L. interrogans serogroup Icterohaemorrhagiae. They were divided in 6 groups, sacrificed from the 1st to the 6th day of infection. Semiquantitative analyses of histopathological liver lesions were performed in 1 micron sections of tissue embedded in glycol-methacrylate. The distribution of leptospiral antigen (L. Ag) and its glycolipoprotein (GLP) was demonstrated by peroxidase-antiperoxidase on paraffin embedded tissue. Significant lesions appeared at the 4th day of infection, progressing to a peak on the 6th day. Inflammation was associated with injury of the portal triad. Liver cells showed either swelling or acidophilic degeneration and necrosis, together with loss of cell cohesion, leading to disarray of liver cell plates. Mitochondria were found progressively enlarged and irregularly distributed. L. Ag expression was parallel to the morphological changes. Portal distribution was significant at the 4th day and on later stages centrilobular localization became predominant. Spiral forms suggestive of intact leptospires were initially found but, chiefly at the 6th day, L. Ag was seen in granules, probably resulting from phagocytosis. GLP staining was similar to granular L. Ag in morphology, and distribution. Cytokeratin condensation was seen in liver cells with acidophilic necrosis and was marked in areas of disorganization of cell plates. Our findings lead us to hypothesize a direct leptospiral cytotoxic effect on endothelial and on liver-cell membranes. At first, leptospires themselves would induce subcellular changes acting mainly on membrane permeability. Afterwards, their granular forms, including GLP, would act as adjuvant factors. These findings demonstrate that the disarray of liver cell plates at the late phase of the disease is genuine.
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Antígenos Bacterianos/análisis , Leptospira interrogans/inmunología , Leptospirosis/microbiología , Leptospirosis/patología , Hígado/microbiología , Hígado/patología , Animales , Cobayas , Queratinas/análisis , Macrófagos del Hígado/patología , Hígado/irrigación sanguínea , Regeneración Hepática , Masculino , Mitocondrias Hepáticas/patologíaRESUMEN
Guinea-pigs were experimentally infected with L. interrogans serovar copenhageni serogroup Icterohaemorrhagiae and their liver and kidney were studied by immunoelectron microscopy using the post embedding indirect immunogold labelling technique. Primary antibody was a purified rabbit anti-serum produced against the same leptospiral strain used in the inoculum. Gold-labelled leptospiral antigen (LAg) was found close to cell membranes of hepatocytes, kidney tubular cells and endothelial cells of the interstitial capillaries of the kidney. Afterwards it was internalized by hepatic and tubular cells, and eventually found in lysosomes. Phagolysosomes of Kupffer cells were also found to contain remnants of degraded leptospires and gold-labelled LAg. Gold-labelled intact leptospires were detected at the enlarged intercellular spaces between hepatocytes at the areas of hepatic cell plate disarray, showing the potential for leptospiral migration during the septicaemic phase of the disease potentially contributing to the pathogenesis of the lesions. The affinity of leptospiral antigenic material for cell membranes suggests an initial interaction with cell surface proteins followed by its internalization and cell damage. The nature of antigenic material detected, however, remains undefined; it may be a toxin, an enzyme or any other factor/s involved in leptospiral virulence.