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Biomedical subjects

G Chioralia

Publications and source records attributed to G Chioralia.

At least 19 recordsLinked to original sources
PubMed2000

Ribosomal RNA of Nosema algerae and phylogenetic relationship to other microsporidia.

Microsporidia are intracellular parasites that are common in invertebrates. Taxonomic classification is mostly restricted to morphologic and physiologic data. Limited data are available about taxonomic classification using DNA-sequence data for analysis. We examined the small-subunit (SSU) rDNA, the intergenic spacer (ITS) region, and a part of the large-subunit (LSU) rDNA of Nosema algerae, a parasite of mosquitoes, taken from a laboratory colony of Anopheles stephensi. Target gene amplifications were done by polymerase chain reaction (PCR) and, after cloning, DNA fragments were sequenced. The SSU-rDNA sequence obtained was aligned with several other microsporidian SSU-rDNA sequences available from the GenBank or EMBL data bases and was analyzed by different methods. On the basis of the results of our phylogenetic analysis, we suggest that our N. algerae isolate is not closely related to other microsporidia belonging to the genus Nosema.

Animals↗
PubMed1998

Morphologic changes in Nosema algerae (Microspora) during extrusion.

As a member of the phylum Microspora, Nosema algerae is a small obligate intracellular parasite. Its free invasive stage is a spore with a characteristic cellular organization, including an apically anchored polar tube that serves as a tool for the transmission of genetic material into the host cell. By detailed electron micrographic documentation of the spore ultrastructure we present the aspects related to the biologic process of spore extrusion. Our ultrastructure findings confirm that the extrusion process of microsporidian spores is based on extreme changes in their organization. This study is the first complete ultrastructural documentation of N. algerae concerning the extrusion process, which can be subdivided into different stages: the breakdown of the microsporidian cellular compartmentation; the filling of a preformed polar tube with modified sporoplasm; the uncoiling of the polar tube, which in this stage has reached its final length; and, finally, its extrusion and screw-like movement.

Animals↗
PubMed1998

Relevant criteria for detecting microsporidia in stool specimens.

By using different staining techniques, 479 stool specimens from 212 diarrheic patients with AIDS were examined for microsporidian spores. Calcofluor fluorescence staining of 119 specimens revealed fluorescent ovoid structures of microsporidian size. Staining of these samples according to the method of Weber et al. (R. Weber, R. T. Bryan, R. L. Owen, C. M. Wilcox, L. Gorelkin, and G. S. Visvesvara, N. Engl. J. Med. 326:161-166, 1992) with trichrome produced six specimens with pinkish spores containing the characteristic microsporidian belt-like structure. The 6 specimens were processed for transmission electron microscopy, as were another 21 specimens which did not present the belt-like structure after trichrome staining but which looked highly suspicious after fluorescence staining. In these 21 samples, only fungal spores and, particularly, bacterial Clostridium spores were demonstrated, whereas in the 6 samples diagnosed positive after trichrome staining, the existence of microsporidia could be verified by electron microscopy. Based on our observations, we propose that the belt-like structure seen with the Weber stains in microsporidian spores corresponds to structures existing in priming-stage spores. The results suggest that routine microscopical fecal diagnosis for microsporidian infection should include a screening by fluorescence staining and, subsequently, a confirmatory viewing of fluorescence-positive samples after trichrome staining.

AIDS-Related Opportunistic Infections↗
PubMed1983

[Fluorescence microscopy study of fluorescein in the posterior segment of the eye following local application of drugs].

After local application of gentamicin, dexamethasone and tropicamide to rat eyes, no effect on the permeability or the caliber of retinal vessels was observed, nor any diffusion of fluorescein from the choriocapillaris to the outer retinal layers. The qualitative assessment of fluorescence microscopic preparations (and photographic reproductions of them) is relatively unreliable and has led to confusion in the literature. The results presented here, which to some extent contradict earlier findings published in 1971, are discussed. The authors expect to obtain more accurate results from the quantitative method which they are now using.

Animals↗
PubMed1982

[Demonstration of ocular blood/tissue and blood/fluid barriers].

In addition to previous fluorescence-microscopic investigations on ocular barriers, quantitative fluorescence-photometric measurements on the eye tissues of albinotic rats were performed. The eyes were enucleated 5-30 min after intravenous injection, and tissue samples were compared with analogous eye tissues of untreated animals. The results were (I) different increases of measured data in the region of endothelium and stroma of the cornea, of vessels and stroma of the ciliary body and iris, of choroid and choriocapillaris, as well as of pigment epithelium and retina vessels; (II) no increase of the photometer values was observed in the epithelium of the cornea and in all other external and internal layers of the retina. It is to be assumed that in contrast to the tissues and vessels mentioned in (I), no measurable amounts of fluorescein have penetrated into the retina layers mentioned in (II). Although the fluorescence-photometric method may not be absolutely conclusive, it could be established that measurements are more exact than the qualitative method performed by fluorescence-microscopic observation.

Animals↗
PubMed1982

8-methoxypsoralen and long ultraviolet effects on the rat lens: experiments with high dosage.

The effect of systemic 8-methoxypsoralen (8-MOP; 100 mg/kg daily) and subsequent long ultraviolet irradiation (UVA; 300 mJ/cm2; peak: 365 nm) on albino and pigmented rat eyes was studied in a 3-dimensional experimental set-up. While 8-MOP and UVA did not cause any ocular pathology when administered alone, a combined application of the two factors caused reversible corneal opacities, and irreversible iris devascularisation and cataracts. The irreversible changes were seen only in the albinos and accompanied by a significant decrease in lens wet weight. Phosphorescence and EPR spectroscopy demonstrated the formation of an 8-MOP-protein photoadduct in the animals treated with both 8-MOP and UVA. The results of this study emphasize the necessity of shielding the eyes of patients on photochemotherapy with protective spectacles.

Animals↗
PubMed1982

[Secondary fluorescence of intraocular vessels of the anterior segment of the rat eye after local drug application (author's transl)].

After local application of gentamycine, dexamethasone and tropicamide to rat eyes, no effect was observed on the permeability of the vascular wall of the iris and ciliary body compared with fluorescein-Na. Nor were there any changes in vessel caliber. The constriction of the dye column observed in corneal neovascularizations was not seen in the (normal) iris vessels and the vessels of the ciliary body. With regard to the iris region, however, this might be due to mechanical causes and/or the possibility that vessels of different origins react differently.

Administration, Topical↗
PubMed1979

[Behavior of fluorescein dye in the vascularized cornea of the animal eye after local application of certain drugs (author's transl)].

In pigmented rabbits we investigated the much-used drugs pilocarpine, atropine, and tropicamide (Mydriaticum, Roche) with regard to their possible influence on the permeability of newly formed corneal vessels. Sodium fluorescein was chosen as test substance. Corneal vessels were produced by introcorneal injection of 0.1 N NaOH. Their development required 2--3 weeks and their growth about 4--6 weeks. A 2-week period of stability followed and was used for the local application of the above drugs. An evident influence on the diffusion of fluorescein could not be ascertained. Tropicamide induced a narrowing of the dye column in the corneal vessels. This phenomenon may be due to a narrowing of supplying vessels. In all cases, dye diffusion took place especially at the peripheral loops of the corneal vessels.

Animals↗
PubMed1979

[Differences in permeability for FITC-dextrane in cornea neovascularisation (author's transl)].

3 weeks after NaOH cauterization of rat corneas, the newly formed vessels were angiographically investigated by means of FITC dextran fractions. An angiographic picture similar to that of fluorescein Na was observed after intravenous administration of FD 3. A minimum diffusion of FD 40 could only be detected in the area of the distal terminal loops of the newly formed corneal vessels. FD 70 and FS 150 shoed an angiographically similar behaviour with no diffusion in the whole area of neovascularization.

Animals↗
PubMed1978

[Limited diffusion of dye between choroid and retina during animal experiments after injection of fluorescein and rhodamin (author's transl)].

For contributing to the question of an existence of a diffusion of the unbound part of the fluorescein between choroid and retina in fluorescein angiography, on pigmented rats, after intravenous injection of Fluorescein sodium and Rhodamine B respectively, comparing observations were effectuated. Rhodamine B in its unbound form showed a distinct diffusion between choroid and retina and coloured all retinal layers in the late phases whereas in the case of the Fluorescein sodium, only a poor diffusion was observable. The similar spectral bands of the primary and secondary fluorescences render difficult the observation of the behaviour of the fluorescein dye.

Animals↗
PubMed1977

[Regression of corneal neovascularization by laser treatment? (author's transl)].

The corneal neovascularization produced by NaOH burns was examined in two groups of pigmented rabbits following laser treatment. The treatment was carried out with energy level 500 mW, spot diameter 200 micron, and exposure time 1 s throughout. In the first group, a single newly formed vessel was coagulated in each case. Subsequent fluorescein angiography invariably showed an incomplete occlusion of the vessel. In the second group, we coagulated a section of the neovascularization network at its origin in the corneal limbus. After 48 h, fluorescein perfusion was once again observed, but the vessels were predominantly finer than before. Fluorescence microscopy revealed a rich neovascularization of the more superficial layers of the corneal stroma. To be successful, laser treatment must involve both supplying and draining vessels.

Animals↗
PubMed1976

[Experimental fluorescein angiographic and microscopic investigations on laser treated rat eyes (author's transl)].

On fundi of pigmented rats, with Argon laser constantly 300 mW of power. 2 seconds exposure time and 50 microns spot diameter, coagulations have been performed. The eyes have been observed up till 3 months after the intervention, then angiographies were performed, and the following enucleated eyes have been examined with the fluorescence microscope. Neovascularizations and dye diffusions were observable mainly in the marginal zones of the arised cicatrices. The neovascularizations were starting from the choroid and penetrating into the outer retinal layers.

Animals↗
PubMed1976

Observation of injected fluorescein diffusion after laser treatment of cat fundi. An experimental study with angiography and microscopy.

Argon laser coagulations with a power of 100 mW and 300 mW, exposure time 0.02 and 0.02 sec, and constant spot size of 100 microns were applied on normal cat fundi. From 1 and 2 hrs to 7 days after the coagulation, the treated eyes were observed angiographically and by fluorescence microscopy after dye injection; freeze dried eyes were examined under a fluorescence microscope. Abnormal dye leakages originated from the chorid and from retinal vessels were detected in the specimens examined within 72 hrs after the coagulation.

Animals↗