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Biomedical subjects

F Malecaze

Publications and source records attributed to F Malecaze.

At least 19 recordsLinked to original sources
PubMed1992

Giant retinal tears. Surgical techniques and results using perfluorodecalin and silicone oil tamponade.

Intraoperative use of perfluorocarbon liquids in the management of giant retinal tears was introduced about 4 years ago. Twenty-four patients were operated on for giant retinal tears using perfluorodecalin and silicone oil tamponade. All patients underwent pars plana vitrectomy, unfolding of the giant retinal tears by perfluorodecalin, perfluorodecalin-silicone oil exchange, and endophotocoagulation. The lens was removed in 10 of 14 phakic patients, and encircling scleral buckle was placed in 18 cases. Twenty-three of 24 retinas remained successfully attached with a minimum of 6 months of follow-up. Short-term results of intraoperative use of perfluorodecalin and silicone oil tamponade in the management of giant retinal tears are encouraging. Perfluorodecalin offers the advantage of low cost compared with other perfluoro-carbon liquids like perfluoro-n-octane. The exchange with silicone oil offers the advantages of easy removal of perfluorodecalin and absence of posterior slippage of the retinal tear.

Adolescent↗
PubMed1992

Inhibition of intraocular fibrin formation with annexin V.

Annexin V is a member of the calcium- and phospholipid-binding proteins, known to have an antithrombotic effect. For the first time, we have tested its ability to prevent intraocular postoperative fibrin formation in a standardised rabbit model and compared its effect with that of heparin. Annexin V, 20 micrograms and 60 micrograms, injected in the anterior chamber post-operatively, significantly reduced the area of the fibrin clot and its time to clearing. Annexin V appeared to be as efficient as heparin. It probably acts by preventing phospholipids from playing their role in the coagulation cascade which leads to fibrin formation. Furthermore, annexin V has an anti-inflammatory effect by protecting phospholipids from phospholipase A2 activity. Therefore, annexin V might be considered as a new therapeutic agent acting both on fibrin formation and inflammatory processes.

Animals↗
PubMed1992

[Surgery of retinal detachment of patients with pseudophakia using the panfunduscope].

Examination of the extreme periphery of the fundus of patients with pseudophakic retinal detachment is difficult due to poor pupil dilatation, optical aberrations from the intraocular lens, opacification of the posterior capsule or peripheral capsular remnants. Fifty-one patients with pseudophakic retinal detachment were operated on with using the wide angle panfunduscope of Rodenstock. It allows a very satisfactory pre- or intraoperative view of the extreme periphery of the fundus using the slit-lamp of the operative microscope combined with a scleral indentation. In only 3 cases no break was found in spite of pre- and intraoperative examination of the fundus periphery with the panfunduscope. Anatomic success was achieved in 47 out of 48 patients with a minimum of 6 months of follow-up; 3 patients were lost to follow-up. The mean postoperative visual acuity was 0.5. Unlike other methods of fundus examination, such the 3 mirror Goldmann lens or the indirect binocular ophthalmoscope, the panfunduscope allows good visualization of the peripheral retina of patients with pseudophakic retinal detachment using the slit-lamp of the operative microscope combined with a scleral indentation. Thus, small peripheral retinal breaks, often associated with pseudophakic retinal detachment, can be identified.

Adult↗
PubMed1992

[Leber's optic neuropathy: new diagnostic prospects].

The diagnosis of Leber's hereditary optic neuropathy, essentially based on a family history of a similar illness, becomes difficult in sporadic cases. In this disease, mitochondrial DNA mutations have been recently discovered and detected by digestion with restriction enzyme after amplification by the Polymerase Chain Reaction. We present two patients in whom these molecular biological techniques confirmed the diagnosis of Leber's hereditary optic neuropathy in the absence of a convincing family history. These new molecular biological methods, providing a precious diagnostic test, would certainly play a greater part in genetic counselling and would probably be a prerequisite for the development of new forms of therapy.

Adult↗
PubMed1991

Role of interleukin 6 in the inflammatory response after cataract surgery. An experimental and clinical study.

The mechanism of uveitis following cataract surgery, which is mediated in part by the cyclooxygenase pathway, is complex, the complexity of which is likely to be due to several factors. We investigated the possible local involvement of interleukin 6 (IL-6) in this response. Using a specific bioassay, we showed a dramatic increase of IL-6 levels (> 4 x 10(3) times) in all of the aqueous humors of 12 patients following cataract surgery. The IL-6 levels in serum samples were below detection limits, indicating a local production of this cytokine. In addition, the injection of highly purified recombinant interleukin 6 in the anterior chamber of the eye in rabbits resulted in an inflammatory response. These observations suggest that IL-6 may play a crucial role in the occurrence of inflammation after cataract surgery, and it may lead to new therapeutic approaches to this problem.

Animals↗
PubMed1991

Localization of acidic fibroblast growth factor in proliferative vitreoretinopathy membranes.

The pathogenesis of proliferative vitreoretinopathy (PVR) membranes remains poorly understood. We have studied the presence of acidic fibroblast growth factor (aFGF), a potent mitogen for many cells, within these membranes. We have used affinity purified monospecific anti-aFGF polyclonal antibodies, in conjunction with highly sensitive immunofluorescence techniques. The labelling was exclusively localized to cell bodies and was absent from the extracellular matrix. Double labelling techniques revealed that all cytokeratin positive cells (probably pigmented epithelial cells) and macrophages contained aFGF-like immunoreactivity, whilst glial cells were unlabelled. Appropriate controls indicated the specificity of the antibodies. Hence, the presence of this mitogenic molecule within certain cell types constituting PVR membranes may contribute to the pathogenesis.

Animals↗
PubMed1991

[FGF and physiopathological implications].

The role of FGF in retinal pathologies can be considered in two respects: 1-as a causative agent (for instance, stimulating aberrant growth or abnormally affecting some aspects of cellular behaviour), or 2-as a possible therapeutic drug (for instance, its ability to rescue neuronal cells from programmed or surgically-induced death), there is evidence for both: the retina, particularly the photoreceptors (PR), seems to be highly succeptible to a host of genetic defects, for instance, in the rat mutant RCS a defect in the pigmented epithelial cells (RPE) leads to the destruction of the PR. Transocular injection of FGF into RCS rats reduces the rate of PR cell loss. On the other hand, we have recently identify a difference in FGF-Receptor cell biology in the RCS mutant which may underline this particular dystrophy. Cultures of purified RPE cells were established from the dystrophic RCS rat and its congenic normal sighted control, and the number and affinity of cell surface FGF-R determined by incubation with 125I-bFGF. Scatchard analysis of the bining data indicated that whereas affinites were in both strains around 60pM, there was a large reduction in receptor number, about 70% in the mutant. Analysis of other FGF/FGF-R criteria, such as mitogenic activity, receptor molecular weight and the profile of FGF degradatoin showed no significant differences between the strains. Thus, defects in the FGF/FGF-R regulating system may actually led to retinal degeneration (RCS rat). But, once again, the underlying principles of FGF mechanisms of action in vivo are at present too incompletely understood to permit rationalization of these various observations.

Animals↗
PubMed1991

[Extracapsular cataract extraction and implantation in the capsular sac during vitrectomy in diabetics].

Removal of the lens is often performed during pars plana vitrectomy for complications of proliferative diabetic retinopathy, but correction of aphakia often remains unsatisfactory. Some authors have reported posterior chamber intraocular lens implantation during pars plana vitrectomy in diabetic patients who presented with coexisting cataract and vitreoretinal complications from proliferative diabetic retinopathy. Some patients were operated by pars plana lensectomy and vitrectomy followed by posterior chamber intraocular lens implantation in the ciliary sulcus, others by extracapsular extraction, posterior chamber intraocular lens implantation in the ciliary sulcus, and pars plana vitrectomy. Other authors have described phacoemulsification through the limbus, pars plana vitrectomy and implantation in the capsular bag in one operation in various indications, including complications of proliferative diabetic retinopathy. We inserted a posterior chamber intraocular lens into the capsular bag in 18 eyes of 16 patients with complications of proliferative diabetic retinopathy after extracapsular cataract extraction and pars plana vitrectomy in a single session. A standard extracapsular cataract extraction was performed before pars plana vitrectomy. Sufficient anterior capsule was left in place in order to facilitate implantation in the capsular bag after pars plana vitrectomy. The anterior chamber was filled with sodium hyaluronate in order to maintain anterior chamber depth, corneal clarity, and good mydriasis during the continuation of the procedure. A standard three port pars plana vitrectomy was performed in all cases. After closure of superior sclerotomies, superior corneal incision was partially reopened, an intraocular lens specifically designed for the capsular bag with an optic size of 7 mm was inserted, and the corneal incision was closed with interrupted 10/0 sutures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Opposing effects of basic fibroblast growth factor and transforming growth factor-beta on the proliferation of cultured bovine retinal capillary endothelial (BREC) cells.

Transforming Growth Factor-beta (TGF-beta) inhibits the serum and basic fibroblast growth factor (bFGF)-induced proliferation of cultured bovine retinal endothelial capillary (BREC) cells in a dose-dependent manner. The concentration of TGF-beta required to get half-maximal inhibition (ED50) are 10 pg ml-1 in serum and 17 pg ml-1 in the presence of additional bFGF (1 ng ml-1). These TGF-beta ED50 values are greatly increased when BREC cells were seeded at high density: 610 pg ml-1 in serum and 1 ng ml-1 in the presence of additional bFGF. At low initial cell density BREC cells are more sensitive to TGF-beta than aortic bovine arch endothelial (ABAE) cells for which TGF-beta ED50 values are respectively 40 pg ml-1 and 100 pg ml-1 in serum and in the presence of additional bFGF. In contrast, at high cell density BREC cells appeared to be more resistant to TGF-beta inhibition than ABAE cells for which TFG-beta ED50 values are 210 and 300 pg ml-1. Moreover bFGF added at increasing concentrations neutralize totally TGF-beta inhibition of BREC cell proliferation but only partially that of ABAE cell proliferation. Our results suggest a key role of equilibrium TFG-beta bFGF on the proliferation of BREC cells.

Animals↗
PubMed1989

Autocrine regulation of bovine retinal capillary endothelial cell (BREC) proliferation by BREC-derived basic fibroblast growth factor.

Fibroblast growth factors (FGFs) are mitogenic for bovine retinal capillary endothelial cells (BREC) seeded at a low density. Seeding BREC cells at a high density greatly reduces their requirement for basic FGF (bFGF) in order to proliferate actively. We show here that monolayers of BREC cells synthesize and release into the culture medium a growth factor, which on the basis of biological activity, heparin affinity, immuno-cross reactivity with anti-bFGF antibodies and mRNA analysis, has been identified as basic fibroblast growth factor. These data indicate that BREC cells are able to synthesize and release bFGF, which can act as a promoting-growth factor for these cells by a para- and/or autocrine mechanism. We suggest thus, that this para- and/or autocrine mechanism involving bFGF may play a key role in preretinal neovascularization, particularly in diabetic patients presenting a proliferative retinopathy.

Animals↗
PubMed1989

[Culture of retinal capillary endothelial cells].

The culture of retinal capillary endothelial cells involves certain problems concerning contamination by pericytes, the maintenance of differentiation and the duration of culture viability. A procedure for the isolation and culture of capillary endothelial cells from bovine retina which overcomes these difficulties, is described. Microvessel fragments isolated by mechanical dispersion and filtration techniques adhere strongly to dishes coated with extracellular matrix produced by bovine corneal endothelial cells. The first migrating cells emerge from the original microvessel fragments two days after plating. This technique and subsequent cloning provides migrating and proliferating cells derived only from the retinal capillaries and uncontaminated by other cell types such as pericytes. Endothelial cells were grown on gelatin coated dishes in a serum supplemented medium (10% calf serum). Cell proliferation was significantly enhanced by the addition of basic fibroblast growth factor (1 ng/ml) to the culture medium. In these culture conditions, retinal capillary endothelial cells can be repeatedly passing without the loss of their principal morphological characteristics and some of the differentiated properties of endothelial cells. Primary cultures and subcultures, at least up to the 8th passage, formed a monolayer of small, elongated, tightly-packed, contact inhibited cells which expressed Factor VIII-related antigen. Ultrastructural examination by transmission electron microscopy of confluent bovine retinal capillary endothelial cells showed many tight junctions and Webel Palade granules. These studies provide new means for the isolation and culture of retinal capillary endothelial cells and presents evidence for growth factor requirements for the ability of cells to be repeatedly passing.

Animals↗
PubMed1988

Immunological analysis of the aqueous humour in candida endophthalmitis. II: Clinical study.

An anterior chamber paracentesis was carried out on six patients with candida endophthalmitis and on control subjects. We endeavoured to find out if there was local production of antibodies by evaluating the anti-candida antibody titres, the immunoglobulin G, and the albumin levels in the aqueous humour and in the serum. A significant difference in the level of specific antibodies between patients and controls was found. Local synthesis of anti-candida antibodies was discovered in five out of six patients with candida endophthalmitis. There would seem to be a correlation between the severity of uveitis and antibody titres.

Adult↗
PubMed1987

Experimental study of the intra-ocular penetration of ketoconazole in rabbits.

We studied 11 healthy rabbits and 15 rabbits with experimentally induced Candida endophthalmitis. Using a microbiological procedure, ketoconazole levels were determined 1, 2, 4, 8 and 24 h after its oral administration. Ketoconazole penetration was average in the aqueous humour, significant in tears and poor in the vitreous. Vitreous penetration was not detectable in healthy rabbits or in rabbits with chorioretinits exhibiting little or no vitreous reaction. Such penetration was only significant in rabbits exhibiting massive vitreous exudation; however, in such rabbits, penetration was not always observed (only in 2 out of 6 animals). Given these results, the treatment of Candida endophthalmitis in humans using ketoconazole would appear to be of questionable value.

Animals↗
PubMed1987

[Local production of specific antibodies in the aqueous humor in experimental Candida endophthalmia in rabbits].

An increasing frequency of ocular lesions due to Candida albicans has been reported, but clinical detection of lesions, which may cause permanent blindness, remains difficult. Hematogenous endophthalmitis caused by Candida albicans in the rabbit is a useful model to study the pathogenesis of the disease, and perhaps to find new methods of biological diagnosis. A suspension of Candida albicans was injected in 15 rabbits, according to the method described by Edwards et al. In 1975, causing uni or bilateral chorioretinitis in 12 of them. Unaffected eyes were chosen as controls. After aspiration of the anterior chamber fluid, serum and aqueous humour titres of specific antibodies were determined. A local synthesis of IgG antibodies was detected, after comparison of the titres of specific antibodies in the aqueous humour and in the serum, related to the serum and aqueous humour concentrations of IgG antibodies. According to a formula proposed by Witmer and Desmonts in ocular lesions due to different pathological agents, we calculated the "C" coefficient: C = antibody titres aqueous humor/serum x IgG serum/aqueous humor. A local synthesis of specific antibodies in cases of experimental endophthalmitis leads us to believe that aqueous humour aspiration could be used in the diagnosis of endophthalmitis in humans.

Animals↗