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Biomedical subjects

M Lazar

Publications and source records attributed to M Lazar.

At least 19 recordsLinked to original sources
PubMed1995

Nitric oxide synthase inhibitors protect rat retina against ischemic injury.

Elevation of the ocular pressure in the anterior chamber of the rat eye caused major ischemic damage, manifested as changes in retinal morphology. The two most affected structures were the inner plexiform layer, which decreased in thickness by 90%, and the number of ganglion cells, which decreased by 80%. Pretreatment of the animals with N omega-nitro-L-arginine, a nitric oxide (NOS) inhibitor, almost completely abolished the ischemic damage. Administration of aminoguanidine, a NOS inhibitor selective for the inducible enzyme, partially abolished the ischemic damage. Moreover, administration of the NOS inhibitors 1 h after ischemia, also protected the retina from damage, suggesting that similarly acting drugs could be used clinically to limit ischemic injury in humans. We conclude that NOS, and therefore NO, may be involved in the mechanism of ischemic injury to the retina.

Animals↗
PubMed1995

The additive miotic effects of dapiprazole and pilocarpine.

BACKGROUND: Since dapiprazole on alpha-adrenergic agent, produces miosis by paralyzing the dilator muscle, and pilocarpine, a parasympathetic drug, causes miosis by affecting the sphincter, we speculated that the two drugs might have additive effects. METHODS: The additive miotic actions of pilocarpine 2% and dapiprazole 0.5% were evaluated by comparing the effects of two drugs given together and alone on the reversal of mydriasis induced by tropicamide (0.5%) and phenylephrine (10%) in one eye each of 60 healthy volunteers. RESULTS: Dapiprazole and pilocarpine together induced miosis significantly faster than each drug alone, showing additive effects. CONCLUSION: Co-administration of dapiprazole and pilocarpine at the end of the eye examination will induce fast pupillary constriction, which might be useful in preventing the development of an acute attack of angle-closure glaucoma in patients with anatomically narrow angles.

Adolescent↗
PubMed1995

The effects of lidocaine and bupivacaine on the rabbit retina.

The toxic action of two commercial anesthetics, lidocaine and bupivacaine, on the functional and morphologic integrity of the retina was investigated in albino and pigmented rabbits. The experimental drug was injected into the vitreous of one eye, while saline solution was injected into the fellow eye. Retinal function was assessed from the electroretinogram and the visual evoked potential. Retinal structure was examined at the light microscopic level. Ten milligrams of lidocaine did not affect the electroretinogram and the visual evoked potential responses, though structural damage could be detected close to the site of injection. A lower dose of 5 mg did not produce any detectable physiologic or morphologic damage. The only dose of bupivacaine used, 0.5 mg, was not toxic to the albino and pigmented rabbit retinas, as assessed by the electroretinogram, visual evoked potential, and light microscopy. The results of this study demonstrate that lidocaine and bupivacaine are nontoxic to the rabbit retina at concentrations that are effective for retrobulbar anesthesia.

Anesthetics, Local↗
PubMed1995

Influence of the time interval between instillation of two drops of cyclopentolate 1% on refraction and dilation of the pupil in children.

PURPOSE: Because the usual length of time to instill two drops of cyclopentolate 1% (five to ten minutes) is time-consuming and inconvenient to clinical staff as well as to the child and the child's parents, we investigated the influence of the time interval between the instillation of the two drops on refraction and mydriasis in children. METHODS: We conducted a crossover study on 48 children at the Tel-Aviv Medical Center. Gender, iris color, ethnic origin, and age were recorded. Two cyclopentolate 1% eyedrops were instilled at a one- or five-minute time interval. Retinoscopy was performed and the mydriatic effect was recorded. One week later, the procedure was repeated, this time with a different time interval. RESULTS: The time interval between the instillation of the two drops had no significant influence on retinoscopy results (P = .65 and P = .50 for right and left eyes, respectively) or on pupil dilation (P = .377 and P = .113 for right and left eyes, respectively). CONCLUSIONS: Instilling two drops of cyclopentolate 1% one minute apart is as effective as instilling them five minutes apart.

Child↗
PubMed1995

Congenital fibrosis of the extraocular muscles (autosomal dominant congenital external ophthalmoplegia): genetic homogeneity, linkage refinement, and physical mapping on chromosome 12.

Congenital fibrosis of the extraocular muscles (CFEOM) is an autosomal dominant syndrome of congenital external ophthalmoplegia and bilateral ptosis. We previously reported linkage of this disorder in two unrelated families to an 8-cM region near the centromere of human chromosome 12. We now present refinement of linkage in the original two families, linkage analysis of five additional families, and a physical map of the critical region for the CFEOM gene. In each of the seven families the disease gene is linked to the pericentromeric region of chromosome 12. D12S345, D12S59, D12S331, and D12S1048 do not recombine with the disease gene and have combined lod scores of 35.7, 35.6, 16.0, and 31.4, respectively. AFM136xf6 and AFMb320wd9 flank the CFEOM locus, defining a critical region of 3 cM spanning the centromere of chromosome 12. These data support the concept that this may be a genetically homogeneous disorder. We also describe the generation of a YAC contig encompassing the critical region of the CFEOM locus. This interval has been assigned cytogenetically to 12p11.2-q12 and spans the centromere of chromosome 12. These results provide the basis for further molecular analyses of the structure and organization of the CFEOM locus and will help in the identification of candidate genes.

Chromosome Mapping↗
PubMed1995

Ocular pigmentation protects the rabbit retina from gentamicin-induced toxicity.

PURPOSE: This study was designed to investigate the possibility that gentamicin-induced retinal toxicity is dependent on ocular pigmentation by comparing the effects of the drug on the functional and morphologic integrity of the retina in albino and pigmented rabbits. METHODS: In each rabbit, a solution of gentamicin sulfate was injected into the vitreous of one eye, and saline was injected into the other eye. Retinal function was assessed by electroretinogram (ERG) at different time intervals after injection. Retinal structure was examined at the light microscopic level. RESULTS: In albino and pigmented rabbits, functional retinal damage developed to a maximal level within the first week after gentamicin injection. Thereafter, gradual recovery could be seen in eyes that suffered less than 80% maximal reduction in the ERG b-wave. For each dose >0.1 mg studied, retinal damage was more severe in the albino rabbits than in the pigmented ones. The degree of damage was not affected by the level of ambient illumination, nor was it reduced by the administration of N-acetylcystein, a free radical scavenger, together with gentamicin. CONCLUSIONS: Ocular pigmentation partially protects the rabbit retina from the toxic action of gentamicin. This protection probably reflects binding of the drug by the melanin, which thereby reduces the concentration of the free gentamicin. When the initial gentamicin-induced retinal damage is expressed in < 80% reduction in the ERG, substantial recovery may occur in both strains of rabbits.

Albinism↗
PubMed1995

CT appearance of a traumatic cataract.

We describe a case of a traumatic cataract that presented on CT as a hypodense lens with a hyderdense rim. The finding reflects the pathogenesis of this entity: a capsular tear and consequent entry of fluid into the lens.

Cataract↗
PubMed1995

Panuveal malignant mesenchymoma.

Intraocular malignant mesenchymal tumors are very rare, and only a few case reports of such primary and metastatic tumors have been reported. We report a case of a malignant mesenchymoma involving the entire uveal tract. A 21-year-old woman presented with a tumor on the whole iris of the right eye, which caused intractable glaucoma. Upon enucleation of the eye, a very anaplastic tumor was found to occupy the whole uveal tract; its features were compatible with a tumor of mesenchymal origin, including rhabdomyosarcomatous and liposarcomatous characteristics. Choroidal osteoma was a coincidental finding. The histologic findings of the tumor were of two types of malignant mesenchymal tumors, and therefore the diagnosis of malignant mesenchymoma was made. This is to our knowledge the first tumor of its kind to be reported intraocularly.

Adult↗
PubMed1994

Application of eye drops to the medial canthus.

BACKGROUND: Our purpose was to investigate the efficacy of instillation of eye drops in the medial canthus with the lids closed at the time of application. METHODS: The pupils of 50 healthy volunteers were dilated with tropicamide 0.125%. The effect of the drug on pupillary dilatation when instilled in one eye with the lids closed was compared to its effect when instilled in the conventional mode in the other eye. RESULTS: Maximal mydriasis achieved was 2.75 +/- 0.76 mm in the eye with closed lids and 2.8 +/- 0.77 mm in the eye in which eye drops were instilled in the conventional mode. CONCLUSION: Eye drop instillation in the medial canthus with the lids closed at the time of application seems to be an effective means of ophthalmic drug delivery.

Adult↗
PubMed1994

Opening by the Nd:YAG laser of the anterior portion of the capsular bag in the treatment of delayed onset pseudophakic endophthalmitis.

We report on a pseudophakic patient with delayed onset endophthalmitis. The patient was treated twice topically and systemically with antibiotic and steroids with temporary response to treatment. The inflammation recurred twice upon withdrawal of treatment. Upon the third relapse of endophthalmitis the anterior portion of the capsular bag was opened by Nd:YAG laser. A third course of systemic and topical antibiotic and steroid treatment was followed by permanent resolution of inflammation. No relapse occurred during 18 months of follow-up.

Aged↗
PubMed1993

Catecholaminergic neurons result from intracerebral implantation of embryonal carcinoma cells.

A replication-defective retrovirus was used to introduce the marker gene nlsLacZ into the murine embryonal carcinoma (EC) cell line PCC7-S-aza-R-1009. Undifferentiated EC cells were implanted into the central nervous system of adult rats. One month later, the grafted cells continued to express the nlsLacZ gene. Immunohistochemical analysis demonstrated the presence of EC-derived neurons. These neurons were capable of expressing tyrosine hydroxylase and extended neurites into the host parenchyma. EC-derived glial cells could not be detected. There was no evidence of tumorigenicity. These results demonstrate the utility of EC cells for introduction of exogenous gene products into the central nervous system in experimental models of gene therapy.

Animals↗
PubMed1993

Variable phenotypic expressivity of Best's vitelliform dystrophy.

Two families with Best's vitelliform macular dystrophy (BVMD) were investigated ophthalmoscopically and electrophysiologically. Pedigree examination confirmed the autosomal dominant heredity of this disorder with variable expressivity. Extrafoveal vitelline deposits were present in some asymptomatic patients, strongly suggesting that these deposits represent variable expressivity of familial BVMD.

Adolescent↗
PubMed1992

[Acute systemic side-effects of topical timolol for glaucoma].

Topically-administered ophthalmic medication may reach clinically significant serum concentrations, as evidenced by the variety of systemic side effects reported. These drugs may interact with other drugs administered orally and intravenously, increasing the frequency and severity of their side-effects. We report 4 patients examined in the emergency room because of various systemic manifestations, in whom the symptoms could be attributed either to antiglaucomatous eye drops, or to interaction between these eye drops and systemic medication. Considering the high incidence of glaucoma (0.5-2%), physicians should be aware of the systemic side-effects of antiglaucomatous eye drops and of possible interaction between such treatment and systemic medications.

Aged↗
PubMed1992

Dosing problems in the use of topical ophthalmic drops.

The effect of two drops of the same drug, one instilled immediately after the other, was compared to the effect of a single drop in 100 healthy volunteers. The drugs investigated were tropicamide, 0.125%, and phenylephrine, 2.5%. The mydriatic effect of two drops was 30%-35% stronger than the effect achieved by a single drop.

Adult↗