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S Corona

Publications and source records attributed to S Corona.

35 records · Page 2Linked to original sources
PubMed1997

Occurrence of apoptosis in serosa of Periplaneta americana l. (Blattaria: blattidae): ultrastructural and biochemical features.

In 16-17-day-old embryos of Periplaneta americana, the amnion-serosa penetrates the cavity of the middle intestine, where it forms a cluster of compressed roundish cells. We demonstrated that these cells degenerate throughout apoptosis. The programmed cell death revealed by morphological and biochemical approaches showed all the apoptotic steps: chromatin fragmentation and pyknosis, cytoplasm condensation, karyorrhexis, cytoplasm cleavage. Nevertheless, some ultrastructural peculiarities (atypical heterochromatin arrangement, appearance of nuclear envelope protrusions, absence of nucleolar structures) suggest that the apoptotic expression partially depends on the biological situation (type of organism and inducing factors) in which the programmed cell death takes place. The presence of histiocytic cells internalizing cell debris, of apoptotic and non-apototic derivation, may be correlated with the importance of recycling substances useful for embryo growth.

Journal Article↗
PubMed1997

Pulmonary microsporidiosis due to Encephalitozoon hellem in a patient with AIDS.

The microsporidian Encephalitozoon hellem is being reported with increasing frequency in HIV-positive subjects, as an agent of disseminated microsporidiosis without involving the gastrointestinal tract. We describe a case of pulmonary microsporidiosis in a 27-year-old Italian man with AIDS who developed fever, cough, and dyspnea. A chest X-ray showed multiple bilateral pulmonary opacities and mediastinal lymph-node enlargement. Stained smears of bronchoalveolar lavage sediment showed oval structures consistent with microsporidian spores. Viral, bacterial and fungal cultures were repeatedly negative, whereas microsporidia were successfully cultured in human and bovine fibroblast cell lines. Analysis of electron micrographs indicated that the isolate belonged to the genus Encephalitozoon. Based on further immunological, biochemical and molecular studies it was characterized as E. hellem. Even though a temporary improvement with albendazole therapy was noticed, the patient deteriorated clinically and died of severe respiratory distress.

AIDS-Related Opportunistic Infections↗
PubMed1997

Phylogenetically distant intracellular symbionts in termites.

Cockroaches are known to harbour intracellular bacteria in specialised cells (mycetocytes, or bacteriocytes) of the fat body. In termites, mycetocyte bacteria have been observed only in Mastotermes darwiniensis. These symbionts are thought to have originated from a bacterium that infected an ancestor common to cockroaches and termites. Thus, loss of the infection should have occurred during evolution in all termite lineages, with the exception of that leading to M. darwiniensis. One might suspect that traces of the ancient infection may be present in some termites, in the form of non-mycetocyte intracellular bacteria (e.g. a small number of bacteria within normal cells). Indeed, circumstantial evidence for the presence of intracellular bacteria in two termite species has been reported. However, no data are available on the actual distribution of these bacteria in termites, or on their relationships with the mycetocyte bacteria of cockroaches and M. darwiniensis. In this paper we report results indicating that non-mycetocyte intracellular bacteria are widespread in termites. These results were obtained by electron microscopy on representatives of nine termite species. In addition, sequence analysis of the 16S rRNA genes indicated that the non-mycetocyte bacteria of termites belong to the wolbachia group of the alpha-2 subclass of the proteobacteria. These latter bacteria are not related to the mycetocyte bacteria of cockroaches and M. darwiniensis, which belong to the blattabacterium group of the flavobacteria-bacteroides. PCR analyses with primers specific for wolbachia or blattabacterium provided further support for the identification of the observed non-mycetocyte bacteria as members of the wolbachia group.

Animals↗
PubMed1994

Restoration by piroxicam of liver glutathione levels decreased by acute ethanol intoxication.

The effect of piroxicam, a nonsteroidal anti-inflammatory drug, on blood ethanol and on triacylglycerols, malondialdehyde and glutathione levels in liver of fed rats acutely intoxicated with ethanol was studied. As previously reported for fasted rats, piroxicam in fed rats decreases the concentration of ethanol in blood and inhibits the hepatic increase of triacylglycerols and malondialdehyde consequent to ethanol administration. In addition, the hepatic depletion of reduced and reduced plus oxidized glutathione observed 8 and 12h after gavage of ethanol was reversed when piroxicam was administered simultaneously with ethanol. The importance of the finding is discussed in light of the paramount participation of glutathione during the cellular oxidative stress.

Alcoholic Intoxication↗
PubMed1990

[A family outbreak of acute hepatic fascioliasis].

The diagnosis of human fascioliasis was established in an 11 year old boy with prolonged fever by complement fixation and ELISA tests. Good clinical response followed the treatment with emetine. Four other family members were also affected with the disease and their treatment was equally effective. The origin of the infection was traced to the ingestion of infected watercress at a site 15 km away from Santiago.

Acute Disease↗
PubMed1989

[Multiple hydatid cysts and generalized cysticercosis].

A 64 year old male presented with parotid gland swelling and neck and pulmonary nodules. Contrast and scintigraphic studies ruled out a primary process of the gland. Other nodules were detected in the abdomen and upper limbs. Biopsy of one of these showed C cellulosae and a positive serologic test followed. On the other hand echographic findings support the diagnosis of lung hydatid disease.

Cysticercosis↗
PubMedDate not supplied

Mediterranean leishmaniasis in HIV-infected patients: epidemiological, clinical, and diagnostic features of 22 cases.

Twenty-two Italian HIV-infected patients developed leishmaniasis, clinically manifested as visceral (13 cases), cutaneous (2 cases) and disseminated disease (7 cases). Twenty were males and two females (mean age: 32.8 years) with a mean CD4+ cell count of 46.8/microliter at diagnosis; risk factors were intravenous drug use (17 patients) and sexual behaviour (two bisexual, two homosexual, one heterosexual). All but one patient lived or travelled in hypoendemic Italian regions and other Mediterranean countries. Apart from the two patients with cutaneous leishmaniasis, the clinico-pathological and biological spectrum of the infection was often atypical, especially in patients with disseminated disease. The diagnosis was routinely made by direct recovery of parasites in biological specimens, mainly in bone marrow aspirate, whereas serology was negative or borderline in most of the patients. Among 17 in vitro isolates, Leishmania infantum was the only species involved with previously undescribed isoenzyme patterns in two cases. Treatment with antimonials and other drugs showed only temporary clinical improvement in some patients. Relapses were the rule. Leishmaniasis confirms itself as an opportunistic infection in HIV-positive persons. Secondary chemoprophylaxis should be considered in cases of relapsing disease.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Microsporidian spore wall: ultrastructural findings on Encephalitozoon hellem exospore.

A study of the spore wall of Encephalitozoon hellem was performed on thin sections, freeze-fracture, and deep-etched samples to obtain information on spore wall organization and composition. Our observations demonstrate that the spore wall is formed by an inner 30-35 nm electron-lucent endospore and an outer 25-30 nm electron-dense exospore. The exospore is a complex of three layers: an outer spiny layer, an electron-lucent intermediate lamina and an inner fibrous layer. Freeze-fracture and deep-etching techniques reveal that the intermediate lamina and the inner fibrous layer result from the different spatial disposition of the same 4-nm thick fibrils. In thin sections the endospore reveals a scattered electron-dense material that appears in the form of trabecular structures when analyzed in deep-etched samples. The presence of chitin in the exospore is discussed.

Animals↗
PubMedDate not supplied

Ultrastructural features of spindle microtubule organization during the nuclear division of Encephalitozoon hellem.

Ultrastructural studies were carried out to describe the nuclear division cycle of a strain of Encephalitozoon hellem isolated from an Italian AIDS patient. The nuclear division occurs during the proliferative vegetative phase and it is characterized by the intranuclear mitosis and by the lack of centrioles. The spindle termini are electron dense spindle plaques (ESPs), resembling to the spindle pole bodies (SPBs) of Saccharomycetes. The ESPs are bifacial organella forming microtubules on both nucleoplasic and cytoplasmic faces. In the outer layer of the spindle plaque are present vesicular elements lined by a double membrane of unknown function. The peculiar morphological features of E. hellem ESPs indicate that both intranuclear spindle and cytoplasmic microtubules are involved in the nuclear division.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Mechanisms of microsporidial cell division: ultrastructural study on Encephalitozoon hellem.

The mitotic process in microsporidian Encephalitozoon hellem, a known human pathogen, has been studied with the aim of elucidating some ultrastructural aspects of its nuclear division. The presence of a nuclear spindle, of "electrondense spindle plaques" associated with the nuclear envelope and of cytoplasmic double walled vesicles are reported. We suggest that these "electrondense spindle plaques" serve as foci for intranuclear and cytoplasmic microtubule arrangements, similar to the microtubule organizing centers within the centrosomes of animal cells. The extent to which the microsporidial division process is comparable with that of more familiar eukaryotes such as yeast cells is discussed.

AIDS-Related Opportunistic Infections↗