RESUMO
Giardia duodenalis is a parasitic protozoan that causes diarrhea and other symptoms which together constitute a disease known as giardiasis. Although the disease has been well defined, the mechanisms involving the establishment of the infection have not yet been fully elucidated. In this study, we show that after 24h of interaction between parasites and intestinal Caco-2 cells, there was an alteration of the paracellular permeability, as observed by an approximate 42% of reduction in the transepithelial electrical resistance and permeation to ruthenium red, which was concomitant with ultrastructural changes. Nevertheless, epithelium viability was not affected. We also demonstrate that there was no change in expression of junctional proteins (tight and adherens) but that the distribution of these proteins in Caco-2 cells after parasite adhesion was significantly altered, as observed via laser scanning confocal microscopy 3D reconstruction. The present work shows that adhesion of Giardia duodenalis trophozoites to intestinal cells in vitro induces disturbances of the tight, adherens and desmosomal junctions.
Assuntos
Junções Aderentes/metabolismo , Desmossomos/metabolismo , Giardia/fisiologia , Giardíase/parasitologia , Junções Íntimas/metabolismo , Citoesqueleto de Actina/metabolismo , Junções Aderentes/parasitologia , Junções Aderentes/ultraestrutura , Animais , Células CACO-2 , Permeabilidade da Membrana Celular , Sobrevivência Celular , Desmossomos/parasitologia , Desmossomos/ultraestrutura , Células Epiteliais/metabolismo , Células Epiteliais/parasitologia , Interações Hospedeiro-Parasita , Humanos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/parasitologia , Junções Íntimas/parasitologia , Junções Íntimas/ultraestrutura , TrofozoítosRESUMO
OBJECTIVE: To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy. INTRODUCTION: In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours. METHODS: The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy. RESULTS: No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed. DISCUSSION: The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation. CONCLUSIONS: Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.
Assuntos
Dermatite Fototóxica/patologia , Desmossomos/ultraestrutura , Epiderme/ultraestrutura , Microscopia Eletrônica de Transmissão/normas , Animais , Vesícula/induzido quimicamente , Vesícula/patologia , Citrus , Modelos Animais de Doenças , Eritema/induzido quimicamente , Eritema/patologia , Frutas , Necrose/induzido quimicamente , Necrose/patologia , RatosRESUMO
OBJECTIVE: To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy. INTRODUCTION: In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours. METHODS: The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy. RESULTS: No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed. DISCUSSION: The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation. CONCLUSIONS: Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.
Assuntos
Animais , Ratos , Dermatite Fototóxica/patologia , Desmossomos/ultraestrutura , Epiderme/ultraestrutura , Microscopia Eletrônica de Transmissão/normas , Vesícula/induzido quimicamente , Vesícula/patologia , Citrus , Modelos Animais de Doenças , Eritema/induzido quimicamente , Eritema/patologia , Frutas , Necrose/induzido quimicamente , Necrose/patologiaRESUMO
The authors studied ultrastructural characteristics of desmosomes from oral squamous cell carcinoma, reporting the cellular differentiation and size of the desmosomes. The length of the desmosome profiles was measured with a Zeiss KS-300. The desmosomes were grouped according to their size and the tumor histological grading. Statistical analysis indicated a significant correlation (p < .001) between the size of the desmosomes and the histological grading group of the malignancy. The comparison of the desmosome size among the tumor histological grading groups also showed significant difference (p < .001). A multiple comparisons test indicated homogeneity in the size of desmosomes within the histological grading groups: 100% in the well differentiated, 95.2% in the moderately differentiated, and 50% in the poorly differentiated group. The preliminary data strongly suggest that the homogeneity of length of the desmosome profiles may be exploited for diagnostic strategies.
Assuntos
Carcinoma de Células Escamosas/patologia , Desmossomos/ultraestrutura , Neoplasias Gengivais/patologia , Neoplasias Labiais/patologia , Neoplasias da Língua/patologia , Carcinoma de Células Escamosas/ultraestrutura , Desmossomos/patologia , Neoplasias Gengivais/ultraestrutura , Humanos , Neoplasias Labiais/ultraestrutura , Soalho Bucal , Neoplasias da Língua/ultraestruturaRESUMO
Ultrastructural features of the cheek oral mucosa of rats (Rattus norvegicus) submitted to experimental chronic alcoholism were studied by transmission electron microscopy. Sixty male rats aged three months and with a mean body weight of 250 g were divided into two experimental groups. The control group received a solid diet (Purina rat chow) and tap water ad libitum. The alcoholic group received the same solid diet but was only allowed to drink sugar cane liquor dissolved in 30 degrees Gay Lussac (v/v). The animals of the two groups were weighed and sacrificed after 60, 120, and 180 days of treatment. Samples of the oral mucosa from the cheek region were dissected and processed for ultrastructural analysis. The results showed cell alterations in the basal and intermediate layer of the mucosal epithelium. The most frequent alterations observed were an increased intercellular space, the presence of lipid droplets in the cytoplasm, and irregular nuclei with a pyknotic aspect.
Assuntos
Alcoolismo/patologia , Mucosa Bucal/efeitos dos fármacos , Mucosa Bucal/ultraestrutura , Animais , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/ultraestrutura , Bochecha/patologia , Citoplasma/efeitos dos fármacos , Citoplasma/ultraestrutura , Desmossomos/efeitos dos fármacos , Desmossomos/ultraestrutura , Modelos Animais de Doenças , Lipídeos , Masculino , Microscopia Eletrônica , RatosRESUMO
The aim of this paper is to establish whether there are cytochemical or ultrastructural alterations in the hepatocytes of patients with primary biliary cirrhosis (PBC) at stages I and II compared with the biopsies from individuals with normal liver. Cytochemical technique with ATP as substrate, transmission electron microscopy (TEM) and freeze fracture were used for the studies. In the normal liver biopsies the ultrastructural cytochemical localization of the enzymatic activity was clearly shown in the bile canaliculi. In the PBC biopsies, the enzymatic activity is increased in the bile canaliculi and is also present in the lateral membranes of the hepatocyte. TEM of the lateral surface of the hepatocyte in normal livers showed a smooth surface without microvilli but in PBC livers a large number of microvilli were seen in the lateral membranes. The Golgi apparatus in these patients was localized not only near the canaliculi (normal livers) but also in front of the microvilli. Freeze-fracture showed normal features in the bile canaliculus junctions of the PBC patients. We suggest that the localization of the enzymatic reaction, microvilli and Golgi apparatus at the PBC hepatocyte lateral membranes may represent a compensatory mechanism for derivation of bile flow and other components from the hepatocyte to the intercellular space.
Assuntos
Cirrose Hepática Biliar/metabolismo , Fígado/metabolismo , Fígado/ultraestrutura , Trifosfato de Adenosina/metabolismo , Desmossomos/ultraestrutura , Técnica de Fratura por Congelamento , Humanos , Fígado/patologia , Microscopia EletrônicaRESUMO
The aim of this paper is to establish whether there are cytochemical or ultrastructural alterations in the hepatocytes of patients with primary biliary cirrhosis (PBC) at stages I and II compared with the biopsies from individuals with normal liver. Cytochemical technique with ATP as substrate, transmission electron microscopy (TEM) and freeze fracture were used for the studies. In the normal liver biopsies the ultrastructural cytochemical localization of the enzymatic activity was clearly shown in the bile canaliculi. In the PBC biopsies, the enzymatic activity is increased in the bile canaliculi and is also present in the lateral membranes of the hepatocyte. TEM of the lateral surface of the hepatocyte in normal livers showed a smooth surface without microvilli but in PBC livers a large number of microvilli were seen in the lateral membranes. The Golgi apparatus in these patients was localized not only near the canaliculi (normal livers) but also in front of the microvilli. Freeze-fracture showed normal features in the bile canaliculus junctions of the PBC patients. We suggest that the localization of the enzymatic reaction, microvilli and Golgi apparatus at the PBC hepatocyte lateral membranes may represent a compensatory mechanism for derivation of bile flow and other components from the hepatocyte to the intercellular space.(AU)
Assuntos
Humanos , Fígado/metabolismo , Fígado/ultraestrutura , Cirrose Hepática Biliar/metabolismo , Trifosfato de Adenosina/metabolismo , Desmossomos/ultraestrutura , Técnica de Fratura por Congelamento , Fígado/patologia , Microscopia EletrônicaRESUMO
OBJECTIVE: To investigate whether ultrastructural changes present in clinically normal oral mucosa could occur in the mucosas of patients with endemic pemphigus foliaceus (EPF) or fogo selvagem (wildfire). PATIENTS: Surgical biopsy specimens were taken from the foreskin of 8 patients with EPF and 3 control subjects, the uterine cervix and vaginal wall of 9 patients with EPF and 2 controls, and the oral mucosa of 5 patients with EPF and 4 controls. The patients received a clinical and histopathologic diagnosis of EPF and all had clinically normal oral and genital mucosas. RESULTS: In the patients with EPF, widening of the intercellular spaces and distended, elongated cytoplasmic projections, the tips of which contained desmosomes and were sometimes disassembled, were evident in all 4 regions studied. At the periphery of the spinous cells, cytoplasmic vesicles apparently containing intact or fragments of desmosomes or half-desmosomes were seen. CONCLUSIONS: The ultrastructural lesions found in the mucosas studied are similar to those previously described in the literature for the oral mucosa of patients with EPF. In the cases of EPF, even though the desmosomal changes occurred in all epithelial layers, blisters did not occur in the mucosas by possible coexpression of desmoglein 1 and desmoglein 3.
Assuntos
Doenças Endêmicas , Mucosa/patologia , Pênfigo/patologia , Adulto , Biópsia , Colo do Útero/patologia , Desmossomos/ultraestrutura , Feminino , Humanos , Corpos de Inclusão/ultraestrutura , Junções Intercelulares/ultraestrutura , Masculino , Microscopia Eletrônica , Microscopia de Fluorescência , Mucosa Bucal/patologia , Pênfigo/epidemiologia , Pênis/patologia , Vagina/patologiaRESUMO
Intercellular junctions are studied in the epithelium lining the testis of the freshwater snail Pomacea canaliculata by conventional staining and lanthanum tracer techniques. The junctional complex consists of belt desmosomes and septate junctions. Septate junctions are of the pleated-sheet type and they are constantly associated with mitochondria. Gap and tight junctions appear to be absent. These septate junctions seem to be the structural correlate of an epithelial permeability barrier that separate the testis from the extrapallial space where the shell elements are deposited. These junctions may contribute to a functional barrier in the male gonad of Pomacea canaliculata. The results indicate that freshwater prosobranchs have junctional structures very close to those found in other molluscs.