Filter by keywords:



Filtering documents. Please wait...

1/7. strongyloides stercoralis: ultrastructural study of newly hatched larvae within human duodenal mucosa.

    AIM: To investigate the ultrastructural features of the newly hatched larvae of strongyloides stercoralis in human duodenal mucosa. methods: Duodenal biopsies from an AIDS patient were studied by transmission electron microscopy to investigate morphology, location, and host-worm relations of newly hatched larvae. RESULTS: Newly hatched larvae were found in the Lieberkuhn crypts within the tunnels formed by migration of parthenogenic females. Delimiting enterocytes were compressed. Release of larvae into the gut lumen was also documented. It was shown that both a thin and a thick membrane surrounded the eggs and larvae, as a tegument derived respectively from parasite and host. Segmentary spike-like waves, caused by contractures of worm body musculature, were observed on the surface of newly hatched larvae, and their intestinal lumen was closed and empty, with no budding microvilli. Immaturity of the cuticle and some degree immaturity of amphidial neurones were found, but there was no evidence of either immaturity or signs of damage to other structures. CONCLUSIONS: Newly hatched larvae of S stercoralis appear to be a non-feeding immature stage capable of active movement through the epithelium, causing mechanical damage. The tegument resulting from the thin and the thick membrane may protect the parasite and reduce any disadvantage caused by immaturity.
- - - - - - - - - -
ranking = 1
keywords = enterocytes
(Clic here for more details about this article)

2/7. Pulmonary and intestinal microsporidiosis in a patient with the acquired immunodeficiency syndrome.

    The microsporidian protozoan organism enterocytozoon bieneusi has been found in enterocytes of the small intestine in patients infected with human immunodeficiency virus, and it has been recognized as an important cause of chronic diarrhea in this patient group. We report the first case of a 41-yr-old man with acquired immunodeficiency syndrome in whom microsporidia were detected in bronchoalveolar lavage fluid, transbronchial lung biopsies, stool specimens, and ileal biopsies. He experienced chronic diarrhea, wasting syndrome, chronic cough, and dyspnea. His chest roentgenogram showed a small left posterobasal infiltrate and a small left pleural effusion. The histologic pattern of microsporidia in his bronchial and ileal tissue and the cellular inflammatory reaction with intraepithelial infiltration by lymphocytes were identical to findings described in duodenal and jejunal enterocytozoon bieneusi microsporidiosis. An association between the presence of microsporidia in the lung and the pulmonary symptoms has yet to be determined. It is not known whether pulmonary microsporidiosis was acquired by the aerosol route, by aspiration, or by hematogenous dissemination from the intestine.
- - - - - - - - - -
ranking = 1
keywords = enterocytes
(Clic here for more details about this article)

3/7. A microsporidian previously undescribed in humans, infecting enterocytes and macrophages, and associated with diarrhea in an acquired immunodeficiency syndrome patient.

    To date, the only microsporidian that has been associated with diarrhea and weight loss in acquired immunodeficiency syndrome patients is the newly identified enterocytozoon bieneusi. A second species is now described that was associated with intestinal symptoms in a 32-year-old, human immunodeficiency virus- seropositive, Native American male homosexual. Stool studies and routine light microscopy of multiple small intestinal biopsies that showed atrophy with acute and chronic inflammation were without apparent pathogens. light microscopy of semi-thin plastic sections, cytochemical stains of paraffin sections, and ultrastructural studies revealed extensive microsporidial infection of enterocytes and submucosal macrophages. No other pathogens were identified. Unlike E bieneusi, this microsporidian appeared to develop within septated parasitophorous vacuoles, and lacked polar disks and clear clefts. It most closely resembled, but was distinguishable from, members of the genus encephalitozoon. awareness of the microsporidia as potential opportunists in acquired immunodeficiency syndrome patients is increasing the incidence of identification of these organisms.
- - - - - - - - - -
ranking = 5
keywords = enterocytes
(Clic here for more details about this article)

4/7. Intestinal microsporidiosis in a Chilean patient with acquired immunodeficiency syndrome (AIDS).

    A 24-year-old male patient with AIDS diagnosed in 1989, and with several episodes of pneumocystosis, was admitted because of a chronic diarrheic syndrome and severe epigastric pain. endoscopy showed a granular duodenal mucosa. light microscopy showed a moderate villous atrophy with round-cell inflammatory infiltration of the chorion. Giemsa, Ziehl-Neelsen, and Gram stains showed microsporidial spores measuring between 1.5 and 2 microns in the supranuclear cytoplasm of some enterocytes. Electron microscopy showed sporoblasts and spores consistent with enterocytozoon bieneusi, with an apparently non-tubular, rather electron-dense polar filament showing up to 7 coils and also a microtubular internal structure with annular disposition, a finding which has not been adequately emphasized in the pertinent literature, probably representing a contractile property of the polar filament, rather than a mere duct for the parasitic sporoplasm to be inoculated.
- - - - - - - - - -
ranking = 1
keywords = enterocytes
(Clic here for more details about this article)

5/7. light and electron microscopic identification of cyclospora species in the small intestine. Evidence of the presence of asexual life cycle in human host.

    This is the first case of cyclosporiasis in which the parasite was clearly demonstrated in a duodenal biopsy by light microscopy. Electron microscopy identified the stages of sporozoite, trophozoite, schizont, and merozoite. Although only asexual forms were identified in our case, the sexual cycle must have taken place in the human host, because oocysts were detected in stools of the patients. Therefore, it appears that cyclospora species require only a single host to complete its entire life cycle. Despite the heavy infection, only enterocytes were invaded. The lamina propria and submucosa were not involved. The morphology of cyclospora in the intestine is similar to that of isospora, but differs from that of cryptosporidium. The morphology of the oocyst of cyclospora resembles that of cryptosporidium, but differs from that of isospora. Thus, a combined study of both stool and intestinal biopsy should readily distinguish cyclospora from cryptosporidium and isospora.
- - - - - - - - - -
ranking = 1
keywords = enterocytes
(Clic here for more details about this article)

6/7. Identification of intracellular stages of cyclospora species by light microscopy of thick sections using hematoxylin.

    cyclospora sp is a recently identified coccidia responsible for enteric infection in humans. Most reports have failed to detect this parasite in intestinal biopsies by light microscopy, although the different stages have been ultrastructurally described in jejunum enterocytes. Very recently, some investigators have reported the detection by light microscopy of parasitophorous vacuoles in intestinal biopsies; however, only transmission electron microscopy (TEM) could clearly identify the parasitic stages. To improve the histological diagnosis without using TEM, we have tested different staining methods in biopsies obtained from a patient infected by the human immunodeficiency virus who was shedding cyclospora oocysts. hematoxylin stain alone for 15 minutes on 5 micrometer-thick sections of duodenal biopsies was found to be the most efficient method for observing different stages of the parasite. In particular, the banana-shaped merozoites were visualized and appeared very similar to the human coccidia Isopora belli. This simple technique may be useful in diagnosing cyclospora infection.
- - - - - - - - - -
ranking = 1
keywords = enterocytes
(Clic here for more details about this article)

7/7. encephalitozoon (Septata) intestinalis: cytologic, histologic, and electron microscopic features of a systemic intestinal pathogen.

    encephalitozoon (Septata) intestinalis affects AIDS patients with CD4 counts <100/microL, causing intestinal and disseminated disease. It must be distinguished from the more common intestinal microsporidian, enterocytozoon bieneusi, and from other microsporidia of extraintestinal tissues, such as encephalitozoon hellem and E cuniculi, because clinical manifestations and treatment differ. In this report, the authors describe the diagnostic features of E intestinalis and illustrate all stages of its life cycle as exemplified by a case studied in detail. spores can be detected by light microscopy in feces, urine, or nasal secretions, but not identified to species. A presumptive tissue diagnosis of E intestinalis can be made if 20 to 50 organisms 1.2-2.5 microm in diameter are seen within vacuoles in enterocytes. The diagnosis is substantiated if organisms also are present in stromal cells. On electron microscopy, the septate parasitophorous vacuole is pathognomonic. E bieneusi occurs only in intestinal and biliary epithelial cells, and never within a vacuole. E hellem and E cuniculi, which are not intestinal pathogens, may cause systemic infection but develop in a nonseptate vacuole.
- - - - - - - - - -
ranking = 1
keywords = enterocytes
(Clic here for more details about this article)


Leave a message about 'Intestinal Diseases, Parasitic'


We do not evaluate or guarantee the accuracy of any content in this site. Click here for the full disclaimer.