Search PubMed⌕ Search

Biomedical subjects

G Renard

Publications and source records attributed to G Renard.

At least 235 records · Page 13Linked to original sources
PubMed1983

[Polymorphic posterior corneal dystrophy. Histological and ultrastructural study of 2 cases].

Optical, scanning and transmission electron microscopy examinations were performed in two cases of polymorphic posterior corneal dystrophy. The first case demonstrated typical clinical features, histologic examination revealing the presence of granular deposits in the posterior stroma, and an anarchic fibrillary zone between the stroma and Descemet's membrane. The latter was thickened, with a normal striated fetal zone, an intermediate zone composed of fibrils and long and short collagen fibers, and a normal adult zone. Cells lining the anterior chamber were of the typical endothelial type. Clinical signs in the second case were less evocative even though the father of the patient presented a typical form. Histology showed similar granular deposits in the posterior stroma, and the fibrillary zone beneath Descemet's membrane, which was thickened and delaminated and composed of three layers. Anterior chamber lining cells were disposed in several layers and had numerous surface microvillosities. They were linked by many desmosomes. These cells were therefore of the epithelial type. Comparing the findings in these two cases demonstrates that whereas many common signs existed there was a fundamental difference between the cell types on the posterior surface of the cornea. A review of all possible hypotheses led to the conclusion that the epithelial type cells are of mesenchymatous origin, similar to endothelial cells, as they possess the identical property of secreting a normal adult type of Descemet's membrane and of ensuring deturgescence of the corneal stroma. The pathological mechanisms involved, probably biochemical in nature, which provoke this anomaly can be fairly precisely determined as developing during fetal life, but they remain totally inexplicable. This hypothesis of a mesenchymatous cell developing into an epithelial type allows polymorphic posterior dystrophy to be regarded as a distinct entity, with similar features to other neonatal posterior dystrophies and a vast group of endothelial dystrophies including, among others, congenital edematous dystrophy.

Adolescent↗
PubMed1983

[Morphologic and quantimetric study of the surface of the corneal epithelium].

Studies were conducted to attempt to demonstrate the presence of a twofold cell population in the superficial cells of the corneal epithelium as seen on scanning electron microscopy. Transmission electron microscopy was used to compare corneas washed with acetylcysteine with unwashed corneas after staining of surface mucosubstances with ruthenium red. Washing was found to remove some of the mucus film deposited by the tears on the epithelial surface. In contrast, both specimens showed a layer of substance, stained by the ruthenium red and more or less abundant according to the cell, which was thick enough to mask the microvillosities on scanning microscopy. Two distinct layers were observed. One of constant thickness was a thin layer which followed the outline of the microvillosities exactly but did not mask them. This was formed of glycocalix itself, a substance of cellular origin which was visible on developed cell surfaces even before desquamation of adjacent cells occurred. The other layer was more heterogeneous and attached to the cell wall, but it cannot be removed by washing with acetylcysteine. It also appeared on developed cell surfaces before adjacent cells had desquamated. The substance could arise from the lacrimal film or the necrozed remnants of superficial cells. It appears to increase in quantity with aging of the cell, and is capable of infiltrating between the microvillosities giving the appearance of dark cells on scanning microscopy. The different cells noted on scanning microscopy vary only by the amount of this mucin-like substance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[Scanning microscopy study of the corneal epithelium. Relation of various aspects to the lacrimal film].

Cells of the superficial layer of the corneal epithelium demonstrate differences in luminosity on scanning electron microscopy which has led to their classification as clear, intermediate or dark cells, differences attributed to varying amounts of surface microvillosities. Evidence is provided confirming that differences between cells is not due to artefacts during preparation or observation of specimens. On the other hand, this technique cannot demonstrate whether different evolutory stages of the same cell are involved. Scanning microscopy cannot confirm a single evolutory epithelial cell are involved. Scanning microscopy cannot confirm a single evolutory epithelial cell cycle from the position of the cell in relation to adjacent desquamating cells, or the study of the cell nuclei. Nor can a satisfactory response to the problem be supplied by studying mucosubstances deposited by the lacrimal film on the surface of the epithelium, either by optical microscopy or after scanning electron microscopy with or without washing with acetylcysteine. The presence of superficial epithelial cells of different appearances on scanning microscopy must be due to variations in the amount of glycocalix, the mucus film adsorbed onto the cell surface.

Animals↗
PubMed1982

Effect of acetylcysteine (Mucomyst) on epithelial wound healing.

The rate of reepithelialization of the rabbit cornea, receiving isotonic NaCl solution and acetylcysteine (Mucomyst) solution at 10 and 20% concentrations, following a superficial epithelial ulcer was studied by fluorescein staining, photography and light microscopy. Acetylcysteine solution does not seem to retard normal epithelial healing compared with control animals which received isotonic NaCl solution.

Acetylcysteine↗
PubMed1982

[Ocular herpes simplex in children (author's transl)].

A series of 38 children with ocular herpes simplex infection is reported. The follow-up periods ranged between 1 and 10 years after the first ocular herpetic involvement. The primary ocular infection occurred in most cases between 2 and 6 years of age, with a similar rate in males and females. The number of recurrences increased with the duration of the follow-up period: during the first 2 years, recurrences developed in 50% of cases and after 2 years, all the children had new herpetic ocular attacks. Idoxuridine treatment failures were found in 11 cases of herpetic superficial keratitis. Ocular herpes simplex in children is a major cause of visual loss and disability. After a follow-up period of 5 years, 75% of patients with herpetic keratitis had a visual acuity of 5/10 or less.

Adolescent↗
PubMed1982

[Effects of anterior chamber perfusion on the rabbit corneal endothelium: a scanning electron microscopy study (author's transl)].

The effects of intraocular irrigating solutions (TC Earle and NaCl 9%) on the rabbit corneal endothelium were evaluated utilizing scanning electron microscopy. Introcular pressure was maintained at 15 or 50 mm Hg. Rate of perfusion was between 50 microliter/min and 2 ml/min. With NaCl 9%, in eyes exposed to high pressure (50 mm Hg) for 2 hours with a rate of 50 microliter/min changes could be detected: rupture of apical junctions and minimal structural changes. Similar lesions appeared with a pressure of 15 mm Hg at a rate of ml/min. With Earle solution, no lesions were seen after 3 hours and minimal changes after 4 hours. Intraocular irrigating solution seems to be more toxic than increased intraocular pressure on the structure of endothelial cells, as seen on scanning electron microscopy. Greater sensitivity of endothelium to perfusion fluid than intraocular pressure probably explains the paradoxical appearance of corneal edema in diseased states, and suggests that endo-ocular surgical procedures require modification.

Animals↗
PubMed1981

[Superficial herpes simplex keratitis. Double-blind comparative trial of acyclovir and idoxuridine (author's transl)].

In a double-blind, randomized trial 52 patients with superficial herpes simplex keratitis were treated with a new antiviral compound, acylclovir (ACV) 3% ointment, or with idoxuridine (IDU) 0.5% ointment. No statistically significant difference was found in the number of patients cured with either drug, but healing was achieved more rapidly with ACV than with IDU.

Acyclovir↗
PubMed1981

Regeneration of the human corneal endothelium.

The ability of the human corneal endothelium to regenerate is studied with the scanning electron microscope through examples of corneal diseases and penetrating keratoplasties. This study does not lead to final conclusions on the possibilities of regeneration of the human corneal endothelium but allows us to say that: --regeneration occurs through size increasing and deformation of the remaining cells. --the increase in number and size of surface microvilli may simply indicate a state of cell activation. --the presence of two nuclei in one cell is probably obtained by amitotic division but no complete mitosis has been seen. --Displacement of endothelial cells is a real progression and the cell is able to overcome obstacles. --the fibroblastic transformation of the endothelial cells is present in man but this may simply represent the migrating form of the cells.

Cornea↗
PubMed1981

[Clinical resistance of herpetic keratitis to antiviral agents (author's transl)].

Clinical resistance of herpetic keratitis to antiviral agents constitutes one of the reasons for failure of treatment after their administration. A retrospective study of 42 cases of superficial herpetic keratitis resistant to IDU, IDU and IDC, and Ara-A demonstrated that in 2 out of 3 cases this resistance appeared in patients previously treated locally with antiviral compounds for anterior ocular lesions. Patients resistant to IDU were then treated with Ara-A, and those not responding to Ara-A, with TFT. Resistance may be observed following this new treatment during the subsequent relapses.

Adolescent↗