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Biomedical subjects

G Renard

Publications and source records attributed to G Renard.

At least 217 records · Page 12Linked to original sources
PubMed1988

Excimer laser trephination in penetrating keratoplasty. Morphologic features and wound healing.

The imprecision of trephination of donor and recipient corneas is a major factor in post-keratoplasty astigmatism. In order to improve the quality of trephination, the authors developed a rotating slit delivery system for noncontact penetrating keratoplasty trephination using the excimer laser at 193 nm. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and light microscopy (LM) demonstrated the superior quality of excimer-cut buttons and recipient beds as compared with those obtained by free hand and suction trephines in human cadaver and rabbit eyes. The laser trephined more regularly and precisely without distortion of corneal topography and with less damage to adjacent corneal tissue. The authors morphologically examined wound healing at 6 hours, 12 hours, 3 days, 5 days, 2 weeks, 2 months, and 3 months after penetrating keratoplasty with laser and mechanical trephination in an animal autograft model. The laser did not cause any adverse alteration of wound healing processes including cellular migration, proliferation, and production of new tissue.

Animals↗
PubMed1988

[Tissue colonization of expanded polytetrafluoroethylene in healthy cornea in the view of its use as a support in keratoprosthesis].

The biocompatibility of polytetrafluoroethylene (E. PTFE) keratoprosthetic skirts was studied for periods of observation from 4 to 14 weeks. In a first experimental study, the authors showed that E. PTFE was well tolerated but without fibrovascular ingrowth. In this study, eight perforating keratoplasties were performed and a disk of E. PTFE with a diameter of 4.5 mm was sutured in and covered with a conjunctival flap. The results show that E. PTFE allows fibrovascular ingrowth without a significant foreign body response or encapsulation. Coverage of E. PTFE with conjunctival was essential for fibrovascular ingrowth and to prevent extrusion and rejection.

Animals↗
PubMed1987

An improved method for the colorimetric assay of lipase activity using an optically clear medium.

Lipase activity can be spectrophometrically measured in an optically clear medium using long chain fatty thioesters of 1-mercapto-2,3-propanediol or 2-mercaptoethanol as substrates. With hexamethylphosphoric triamide solutions of these thiosubstrates, the Michaëlis-Menten constants of lipase from Rhizopus arrhizus were determined. The effects of calcium chloride and of bovine serum albumin on the enzyme activity were established.

Colorimetry↗
PubMed1987

[Keratoprosthesis: study of an expanded polytetrafluoroethylene support].

Expanded Polytetrafluoroethylene (E. PTFE) is an inert vitreous teflon alloplast with a high biocompatibility. It is able to be ingrowth by fibrovascular tissue. Very good results are reported in vascular, abdominal and reconstructive surgery and this suggests a possible use in keratoprosthesis. In this purpose, its tolerance and its embedding in the corneal tissues have been studied. Eight perforating keratoplasties are performed in the rabbit with a diameter of 5 mm. A disk of E. PTFE was sutured on the cornea and examined clinically, histologically and by scanning electron microscopy from 1 to 50 days after the operation. Corneal implants are well tolerated but microscopic examination does not show evidence of fibrovascular ingrowth. A full thickness corneal implant seems uneffective in the absence of a conjunctival flap.

Animals↗
PubMed1987

[The corneal endothelium of diabetic patients. A study using specular microscopy].

As the endothelial cells of the human cornea cannot perform mitosis, any metabolic alteration that destroys the cells should result into a decrease in cell density. This study was designed to demonstrate this phenomenon in diabetics as we know that diabetes alters endothelial cells, capillaries at least. On the assumption that capillary endothelium has the same mesodermal origin and almost the same metabolic function as the corneal endothelium, we tried to verify whether the corneal endothelium from diabetic subjects differs from non diabetic controls. As corneal endothelium can be studied in vivo by specular microscopy, it was interesting to verify whether this method could provide evidence of the conditions of the endothelial cells in the diabetic subject. Our study in specular microscopy involved 101 cases. We found slightly inferior values of the corneal endothelial cells density in diabetic subjects compared to the control subjects but no correlation between the values of endothelial cell density and the various parameters in diabetic patients: age, duration of diabetes, corneal thickness. This is correlated to other studies in which the morphology of endothelial cells differed between diabetic and non-diabetic subjects. We concluded that diabetes alters but does not significantly destroy the corneal endothelial cell. This result must be taken into account in corneal surgery as the diabetic cornea is a high risk cornea.

Adolescent↗
PubMed1987

Excimer laser experimental keratectomy. Ultrastructural study.

Excimer lasers have been shown to produce precise etching and clean incisions of the cornea. On two freshly enucleated human eyes radial incisions and a myopic keratomileusis were performed with a specially designed delivery system. The cornea was then studied by transmission and scanning electron microscopy. The surface of the irradiated area was extraordinarily smooth and clean with a precision greater than 10 nm. The epithelial cells were literally cleaved by the ablation process. The cytoplasm and the nucleus were cut without any damage to the other part of the cell and no disturbance of the cells proximal to the incision. The corneal stroma was cut in a regular and smooth fashion, and the aspects observed with the scanning electron microscope differed mainly from the surface observed after an incision made with a diamond knife. The excimer laser allowed optimal conditions for quick and safe wound healing but the long-term effects on the epithelial cells must be evaluated by further studies.

Cornea↗
PubMed1986

[Breaks in Descemet's membrane. Association with secondary warts. Histologic and ultrastructural study].

We analysed the histological and ultrastructural aspects of corneal buttons obtained by keratoplasty in two patients presenting breaks in Descemet's membrane. The edges of the breaks appear clinically as glassy ridges or ledges and are also called Haab's lines. One patient had a birth trauma and the other had congenital glaucoma. The edges of the breaks coiled anteriorly towards the stroma and were dramatically thickened by a multilaminar Descemet's like membrane that exhibited excrescences within its outer part and that was secreted by regenerated endothelial cells. Only one case was analysed by SEM. Secondary guttuta could not be detected by this technique because it was completely covered by a sheet of newly secreted fibrous tissue that prevented the warts from indenting the endothelial cells. The part of cornea corresponding to the break was also covered by a new thick Descemet's like membrane exhibiting guttate warts. This study is thus a good opportunity to discuss the mechanisms of endothelial and Descemet's membrane regeneration.

Adult↗
PubMed1984

Phase II study of 9-hydroxy-2N-methylellipticinium acetate.

A broad phase II trial of elliptinium was conducted in 105 evaluable patients with advanced solid tumors. The drug was given as a 60-90-min i.v. infusion at a weekly dose of 100 mg/m2. Of 36 breast cancer patients, one achieved complete and six achieved partial response for an overall response rate of 19%. Responses lasted for 12-56 weeks from initiation of therapy. There was also one partial response among 21 patients with squamous cell carcinoma of the lung. No response could be obtained in 17 patients with colon cancer, 13 patients with head and neck cancer and 18 patients with a wide variety of other malignancies. Myelosuppression was minimal. Nausea and vomiting were the most frequent toxic effects. The drug also produced serious xerostomia and acute intravascular hemolysis. Asthenia was common. Other adverse reactions included fever and chills, transient neurologic and cardiovascular manifestations and renal function impairment. Additional work is needed to define optimal modes of drug administration.

Adult↗
PubMed1984

Randomized phase II trial of carminomycin versus 4'-epidoxorubicin in advanced breast cancer.

Sixty-three evaluable patients with advanced breast cancer were randomly allocated to receive three-week intravenous courses of carminomycin (18 mg/m2) or 4'-epidoxorubicin (90 mg/m2). The former yielded one (3%) partial response for nine weeks among 29 patients whereas, in the other arm, nine (27%) of 34 patients achieved partial response for a median of 28 weeks (range, nine to 36 weeks; p less than 0.02). The major toxic effect of these anthracyclines was leukopenia with median white blood cell nadirs of 1,600/microL (range, 300-4,000/microL) versus 1,800/microL (range, 500-4,300/microL), respectively. Acute nonhematologic toxic effects were qualitatively similar but carminomycin produced significantly less gastrointestinal intolerance and alopecia. Patients whose disease failed to respond to first-line anthracycline received doxorubicin (60 mg/m2) every three weeks. Four partial responses were obtained among 19 patients previously treated with carminomycin. Following 4'-epidoxorubicin therapy, one of 12 evaluable patients also attained partial response. Survival curves were not affected by the initial treatment option. Carminomycin has marginal activity against breast cancer whereas 4'-epidoxorubicin deserves further evaluation of its therapeutic index relative to doxorubicin. The design used in this trial appears attractive for prompt phase II evaluation of anthracycline analogs.

Adult↗
PubMed1984

[Hydration of the animal cornea: spectrometric study using proton nuclear magnetic resonance].

The concentration of water in isolated corneas was studied using a Nuclear Magnetic Resonance Protonic (P N M R) technique. The corneas were maintained in moist chambers or in different aqueous fluids in order to compare the results obtained by. P N M R with those provided by classical techniques. The magnetization ratio, associated to water component measured as a function of corneal conservation time has permitted to establish the corneal water content variation. The corneas preserved in moist chamber exhibited a slow dehydration of about 15% in the first day. On the contrary, hydration was evident in liquid media, the strongest in pure water. No significant differences were found between saline, T C Earle medium and Neomycin ophthalmic suspension. P N M R technique give an index of corneal hydration in these conditions and it seems possible to use a P N M R apparatus for the evaluation of a corneal graft before surgery.

Animals↗
PubMed1983

Phase II trial of diaziquone (AZQ) in advanced malignant melanoma.

Forty-two evaluable patients with malignant melanoma received AZQ 27 mg/m2 i.v. every 4 weeks. In 5 patients with poor marrow reserve this dose was reduced to 20 mg/m2. Doses were rapidly escalated when no significant myelosuppression was encountered in previous courses. Twenty-five patients had received no prior chemotherapy. A single partial response was obtained for 3 months. Inconsistent myelosuppression was the main toxic effect in this trial. The median WBC and platelet nadirs were 3200/mm3 (900-19,500) and 105,000/mm3 (33,000-530,000) respectively. In 2 patients leukopenia was complicated by a transient episode of infection. One-third of the patients did not experience significant myelosuppression. Non-hematologic adverse reactions were generally mild to moderate and consisted of nausea and vomiting in 26 patients and alopecia in 1. It is concluded that at this dose schedule AZQ is ineffective against malignant melanoma.

Adult↗
PubMed1983

Combination therapy for dendritic keratitis with human leukocyte interferon and acyclovir.

We treated 45 patients with virologically verified dendritic keratitis with a combination of interferon and acyclovir 3% or with placebo and acyclovir 3% in a double-masked study. One drop of human leukocyte interferon (30 X 10(6) IU/ml) or albumin-placebo was administered daily. Acyclovir ointment was applied five times daily. The mean healing time of the corneal ulcers in 24 patients treated with interferon and acyclovir was 3.9 days and the mean healing time in 21 patients treated with placebo and acyclovir was seven days. The difference was significant (P less than .001).

Acyclovir↗