Biomedical subjects
Publications and source records attributed to G Renard.
The antiviral activity of a new antiherpetic compound called acycloguanosine was compared to the activity of 0.12 per cent idoxuridine against a superficial herpes simplex keratitis in the rabbit, using a multiple microinoculation technique. The results of the acycloguanosine group were better than the other group. No toxic side effects could be detected by slitlamp examination.
Secondary alterations in Descemet's membrance were noted in corneal specimens from 20 patients undergoing transfixing keratoplasty, after examination by optical, and in some cases, by transmission or scanning electron microscopy. The most frequent anomaly, thickening of Descemet's membrance, was observed in cases of prolonged or recurrent corneal affections, particularly interstitial keratitis, advanced forms of keratoconus, cicatricial leukomas, and keratoconus. Thickening was due to juxtaposition, with a normal Descemet's membrance, of repair tissue made up of collagen interspersed with zones of cell necrosis and isolated fibrils. These different layers could be interpreted as successive deposits of reparative endothelial cells, the ultrastructural appearance of each layer being characteristic of the type of cell from which it was derived. In this way, the history of each cornea can be reconstituted, from the original normal endothelial cell to the final endothelial repair cells, passing through all the intermediary types of fibroblastic cells. This relationship between the cells which manufacture descemetic tissue and the structure of Descemet's membrance is particularly evident in Groenouw's macular dystrophy type II in which mucopolysaccarides are deposited. Descemetic verrucosities were observed in interstitial keratitis, of syphilitic origin or not, in one case of keratoconus, one case of buphthalmia, two cases of corneal leukoma, one case of vitreocorneal contact from aphakia, and in cases of Groenouw's type II dystrophy. The lesions are either isolated or spread across the posterior surface of the cornea. They differ from the verrucosities of primary cornea guttata by their irregular disposition, their frequent coalescence, the persistence of an endothelial regenerative process, their ultrastructural characteristics close to those of Hassal-Henlè's bodies, and more particularly by the association of a granular material with narrow and wide interval striated collagen. Various hypotheses are discussed which could provide an explanation why certain cells lay down Descemet's membrance in the form of tuberosities, and why these may present in alignments, but no satisfactory definite conclusion can be reached.
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Antiherpetic activity of a new antiviral agent, Acyclovir (ACV), was compared with that of Idoxuridine (IDU) in the treatment of keratitis induced in rabbits by type I herpes simplex virus (HSV). After topical application for 5 days, both compounds were well tolerated, but ACV was significantly more effective than IDU. Virological tests demonstrated that virus multiplication continued for a shorter period in eyes treated with ACV than in those of controls, or of animals treated with IDU, but early viral regrowth was possible. Using two HSV markers, seroneutralization and thermal sensitivity of cell culture development, variations were observed in a rabbit treated with IDU and in a control animal also. Epithetial regeneration after treatment was assessed by optical microscopy and by scanning and transmission electron microscopy. Epithelial scarring was observed to be almost complete in rabbits treated with IDU. The correlation between therapeutic, virological, and histological results in positive evidence for the use of ACV in HSV-induced ocular lesions.
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The iridocorneal angle of the chick embryo was examined by scanning electron microscopy from the 7th day to the 19th day of development. The mesodermal tissue situated between the corneal endothelium and the iris differentiated into trabecular cells. These cells formed a strip on the 9th day and enlarged on the 13th day to form long cellular fibres. The trabecular meshwork was recognizable on the 15th day and reached full development only on the 19th day. The development of the trabecular meshwork was probably much earlier than is usually described. It began with differentiation of the corneal endothelial cells and these cells acquired a multipolar cell body with long cellular processes. The last stage is probably regulated to avoid an abnormal development of the angle structure. These results can be correlated with those obtained in the morphological examination of the structure of the angle in congenital glaucoma and the "cleavage syndrome" of the anterior chamber.
Four cases of macular dystrophy in siblings were studied, 2 brothers and 2 sisters (49, 52, 55, 57 years old). The two youngest had an associated cornea guttata. We performed histologic, transmission, and scanning electron microscopic studies, and in addition a morphometric analysis of Descemet's membrane and of guttata excrescences. Previous studies have been confirmed and the problem of the relationship between the two conditions of macular dystrophy and guttate excrescences is emphasised.
A case of ocular infection due to adenovirus type 19 is reported. The patient developed a bilateral keratoconjunctivitis with preauricula nodes and a mild general malaise. The virus was isolated from both eyes; serological tests carried out on the serum of the patient were compatible with the diagnosis.
Transfixing keratoplasty was performed in a patient seven years after a lens extraction, following the appearance of corneal edema with hypertony and proliferation of a retrocorneal veil. Scanning electron microscopy examination of the posterior surface of the removed graft demonstrated the presence of a vast cellular veil formed of epithelial cells. The principal characteristics of these cells were their polygonal shape, slightly raised edges, and the presence of numerous surface microvilli. Because of the particular characteristics of this epithelium, scanning electron microscopy can be used to observe mitoses in the deep layer as well as for differentiation of the superficial layers. The epithelial cell appears to be identical, as far as its evolution is concerned, both in the aqueous humor and when in contact with the lacrymal film. When compared with other modern investigational techniques, the scanning electron microscope appears to be an effective method for studying epithelial invasion of the anterior chamber. In fact, optical microscopy is of little value in such cases, and transmitted light electron microscopy too heavy a technique for the results expected. Scanning electron microscopy enables precise definition of epithelial cells and can confirm their corneal or conjunctival origin.
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The various traumatic lesions occurring in the corneal endothelium during phacoemulsification were studied in the eyes of anesthetized rabbits. A comparison was made between the effects of massive perfusion of the anterior chamber with simple isotonic saline or Earle's solution, ultrasound emission, total phacoemulsification, and classical extracapsular extraction. The endothelium was examined by electronic scanning microscopy to cover large areas of the endothelium. Simple perfusion with Earle's solution does not alter the appearance of the endothelium, though some modifications in apical digitations may be observed. Perfusion with isotonic saline solution for 15 minutes modifies the appearance of the endothelial surface, with early necrosis in several cells. Ultrasounds provoke complete necrosis of a few isolated cells but do not cause major changes in most of them. Phacoemulsification produces endothelial ulcerations, probably from the trauma from lens debris. Extracapsular extraction, difficult in the rabbit, is the cause of much larger lesions with cell necrosis and vast areas of ulceration.
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