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Biomedical subjects

C Stefan

Publications and source records attributed to C Stefan.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Secondary cataract; correlations concerning lens surgery and pseudophakia type. Therapeutic aspects].

The study presents the correlations concerning the advent of the secondary cataract depending on the surgical technique and pseudofak type (PMMA, acrylic, siliconic), as well the safety and efficacy of the YAG: Nd capsulotomy. A 3 years clinical retrospective trial was done on 320 eyes operated for senile cataract. The incidence of the secondary cataract was 11.4%, usually after 12 months, (the lower in phacoemulsification using acrylic IOL). Nd: YAG capsulotomy being done in cases with visual acuity lower than 0.6.

Acrylates↗
PubMed2002

[Laser in glaucoma treatment ; 1-year personal experience].

THE AIM OF THE PAPER: The paper establishes the role of the laser treatment in the complex treatment of glaucoma and realizes a comparison between our clinical results and the results from the literature. MATERIAL AND METHODS: Along a period of one year, we have treated a number of 117 glaucoma patients: Open angle glaucoma (POAG), angle closure glaucoma (ACG), normal tension glaucoma (NTG) and symptomathic narrow anterior chamber. The complex treatment consists of medication, laser and/or surgery. To treat the patients, we have used the VISULAS 532 Combi laser, manufactured by Zeiss. RESULTS: The results are presented in a synthetic way for different pathological entities and different methods of laser treatment. CONCLUSIONS: In glaucoma, laser treatment represents a step between the medical treatment and surgery and is a very good alternative when the medication in inefficient or is not well tolerated. Our results are, in majority, similar with those from the literature.

Glaucoma↗
PubMed2002

[The role of Brinzolamide 1% ophtalmic suspension in corneal edema].

PURPOSE: The study is aimed at assessing the efficacy and safety of topical carbonic anhydrase inhibitor (IAC--i.e. ophthalmic suspension of brinzolamide 1%--Azopt) in the treatment of corneal edema. METHOD: For this purpose, we carried out an experimental, epidemiological-operational, randomised, placebo-controlled and double blind study, on three groups of laboratory animals (rabbits): group 1 (5 rabbits) included endothelial corneal injuries inflicted by ultrasound exposure by means of a phacoemulsification sound in both eyes group 2 (5 rabbits) included endothelial corneal injuries inflicted by direct trauma in both eyes group 3 (3 rabbits)--no endothelial corneal lesions (control group) In each group we instilled, all the animals, with ophthalmic suspension of brinzolamide 1% (Azopt), 1 drop t.i.d., in one eye for 14 days (starting the following day after infliction of endothelial injuries, when the corneal edema was evidenced by biomicroscopic examination) and placebo (saline solution 0.9% with the same osmolar and pH values as the Azopt) in the other eye. The assessment was performed throughout the following stages: To: preceding the infliction of corneal endothelial injuries, resorting to: biomicroscopic examination ultrasound pahimetry direct specular microscopy T1: the following day after infliction of corneal endothelial injuries, resorting to: biomicroscopic examination (the assessment of corneal edema) ultrasound pahimetry (measurement of corneal thickness and, hence edema) direct specular microscopy (cell density and endothelial ultrastructure evaluation: cellular polimegetism, pleiomorphism) T2: in the wake of 14 days therapy (after eye removal), adding to the previous examinations: indirect specular microscopy (with the same aim as the direct examination, yet examination carried out from the endothelial side) pathologic examination (using hematoxilin-eosin dye and Van-Gieson dye).

Administration, Topical↗
PubMed2002

[Posterior capsule rupture in lens surgery].

PURPOSE: The paper studies the breaks of the posterior capsule in lens surgery, specifically the incidence, causes, types, management and the methods of IOL implantation. METHODS: For this purpose, a retrospective clinical trial was performed, within: 01.06.1999-31.05.2002, on 346 eyes group operated for senile cataract (without other ocular diseases) Patients were split in two groups, based on surgical technique: group 1 with 208 eyes operated using phacoemulsification and group 2 with 138 eyes operated using extracapsular extraction technique. RESULTS: The incidence of the breaks of the posterior capsule was 8.17% for group 1 (17 eyes out of 208) and 5.07% for group 2 (7 eyes out of 138). In all cases an IOL was used, most of them being placed in the posterior chamber (in bag, in sulcus or sclera-sutured) and infrequently IOL for anterior chamber or with irian support. CONCLUSIONS: Breaks of the posterior capsule is a complication of cataract surgery, but appropriate management (viscoelastic substances, anterior vitrectomy) leads to a good outcome, with no influence on the subsequent evolution.

Cataract Extraction↗
PubMed2002

[Primary open angle glaucoma evolution after surgery].

The authors present a four year (01.02.1998-01.02.2002) clinical retrospective trial, including 209 eyes operated for Primary Open Angle Glaucoma (POAG). 52 eyes (24.8%) out of 209 eyes the progression of the disease was discovered observing the increase of the intraocular pressure (IOP), failure in achieving "IOP target" due to the insufficient filtration, the obstruction of the filtration and the deterioration of the papiloperimetrics parameters. The therapeutic approach consisted of additional medication, filtration revision, subsequent surgical treatment physical end/or classic. The authors suggest a sequence for the operated cases of POAG, but that continued to progress, postoperative IOP "seemingly normal" requiring the follow-up for t e disease, in spite of using entire methods of the treatment.

Algorithms↗
PubMed2001

[Ophthalmologic involvement of intracranial tumors--report of a case].

Bilateral papillary edema is considered to be the expression of a tumoral process that reduces the intracranial space resulting in elevation of the intracranial cerebrospinal fluid pressure. The authors present the case of a 21-year-old man consulting for mild visual loss of the left eye. The ophthalmologic examination showed bilateral papilledema and visual field defects in the left eye (enlargement of the blind spot), with no clinic or imagistic signs of increased intracranial pressure. Intracranial pathologic processes that bear like a tumor, reducing the intracranial space are not always associated with papilledema, but papilledema is always associated with intracranial tumor. Increased intracranial pressure is frequently associated with intracranial tumoral processes, but in this case was not showed increasing of intracranial pressure.

Adult↗
PubMed2001

[Myopic peripheral retinal degenerations].

The article shows periferical retinal degenerations which appear in myopia. The places, the ophthalmoscopical aspect and histopathological aspect of each retinal change and the complications that may appear are presented. In the end some principles of treatment are presented.

Humans↗
PubMed2001

[Trabeculectomy and nonpenetrating surgery in glaucoma].

The purpose of the study is to compare the efficiency of classical trabeculectomy and with the punch and nonpenetrating deep-sclerectomy in patients with primary open angle glaucoma. The studied groups comprise patients with uncontrolled intra-ocular pressure with medical therapy and/or laser. The results of the study emphasize the following conclusions: the decrease of intra-ocular pressure is comparable in classical trabeculectomy and with punch the decrease of intra-ocular pressure is comparable in classical trabeculectomy and nonpenetrating surgery. we consider the non penetrating surgery an interesting alternative to the classical trabeculectomy, with better control of intra-ocular pressure the complications of non penetrating surgery are reduced.

Glaucoma, Open-Angle↗
PubMed2001

[Glaucoma as primary optic neuropathy].

The appearance of the new concept of glaucomatous optic neuropathy directed to idea that high intraocular pressure and vascular insufficiency in the optic nerve head are only risk factors in the appearance of glaucoma. Glaucomatous optic neuropathy is the consequence of progressive loss of the retinal ganglion cells whose axons comprise the optic nerve. A great number of neurotrophic agents are under investigation with the view of preventing the dead of retinal ganglion cells. Induction of cell rescue mechanisms may be an alternate and efficient strategy for neuroprotection. The paper presents both actual data about the pathophysiological mechanisms of glaucoma (neurotrophin deprivation, excitotoxicity caused by glutamate, "ischemic cascade", apoptosis of retinal ganglion cells) and neuroprotective and neuroregenerative therapy and antiapoptotic agents.

Adrenergic beta-Antagonists↗
PubMed2001

[Non surgical alternatives in the treatment of the primitive open angle glaucoma].

Lowering of the intraocular pressure--the main risk factor in glaucoma neuropathy--is the major goal in the treatment for primary open angle glaucoma. The goal of the study is to compare the results of topical administration of the next therapeutical agents: b-blockers, prostaglandin analogs, topical carbonic anhydrase inhibitors and selectives adrenergic a-2 agonists. The studied groups emphasize the efficiency of the first line monotherapy and of the combined therapy, maintaining the quality of life, preserving the visual function, the minimal side effects and the compliance of the patients.

Antihypertensive Agents↗
PubMed2000

Nucleotide pyrophosphatases/phosphodiesterases on the move.

Nucleotide pyrophosphatases/phosphodiesterases (NPPs) release nucleoside 5'-monophosphates from nucleotides and their derivatives. They exist both as membrane proteins, with an extracellular active site, and as soluble proteins in body fluids. The only well-characterized NPPs are the mammalian ecto-enzymes NPP1 (PC-1), NPP2 (autotaxin) and NPP3 (B10; gp130(RB13-6)). These are modular proteins consisting of a short N-terminal intracellular domain, a single transmembrane domain, two somatomedin-B-like domains, a catalytic domain, and a C-terminal nuclease-like domain. The catalytic domain of NPPs is conserved from prokaryotes to mammals and shows remarkable structural and catalytic similarities with the catalytic domain of other phospho-/sulfo-coordinating enzymes such as alkaline phosphatases. Hydrolysis of pyrophosphate/phosphodiester bonds by NPPs occurs via a nucleotidylated threonine. NPPs are also known to auto(de)phosphorylate this active-site threonine, a process accounted for by an intrinsic phosphatase activity, with the phosphorylated enzyme representing the catalytic intermediate of the phosphatase reaction. NPP1-3 have been implicated in various processes, including bone mineralization, signaling by insulin and by nucleotides, and the differentiation and motility of cells. While it has been established that most of these biological effects of NPPs require a functional catalytic site, their physiological substrates remain to be identified.

Amino Acid Sequence↗
PubMed2000

[Changes in myopic refractive errors after 9 months of extensive wear of hydrogel lenses with high oxygen permeability and compared with those with low permeability].

BACKGROUND: A small but significant increase in myopia after extended wear of low oxygen permeability (Dk) hydrogel lenses has been previously reported; however, the specific impact of hypoxia on refractive status and corneal curvature with extended wear are not well documented. THE PURPOSE of this study was to compare the refractive changes induced over a period of 9 months' extended wear with high-Dk fluorosiloxane hydrogel lenses and low-Dk hydrogel lenses. METHODS: Adapted daily wear contact lens wearers were randomly assigned to one of two groups. The low-Dk group wore etafilcon A (Dk = 28) for up to 7 days and 6 nights and the high-Dk group wore lotrafilcon A (Dk = 140) for up to 30 days and nights. Refractive error and corneal curvature were measured at 3-month intervals over 9 month of extended wear. RESULTS: The etafilcon A group demonstrated an average increase in myopia of 0.30 D over the 9 months period; however, no change in spherical myopic correction was measured in the lotrafilcon A group. The cylindrical component did not change in either group. A stratified analysis revealed a greater increase in myopia for low myopes than moderate myopes in the etafilcon A group but no difference in the lotrafilcon A group. Keratometric analysis revealed no change in the etafilcon A group and a small degree of central corneal flattering in both major meridians of 0.35 D in the lotrafilcon A group. CONCLUSIONS: Nine months of extended wear of low-Dk lenses is associated with a small degree of myopic progression in adult myopes that appears to be reversible. Wearing fluorosiloxane-hydrogel lenses of high-Dk had no impact on refractive error and may be associated with a small degree of central corneal flattering.

Adult↗
PubMed2000

[Postcontusion glaucoma].

Secondary posttraumatic glaucoma. Blunt ocular trauma may cause transient or permanent high IOP, occurring immediately or in time after the injury. This study presents some clinical and therapeutical considerations about 16 cases which developed secondary glaucoma. The elevation of IOP was associated with hyphema, iridodialysis, zonular tears (with lens luxation or subluxations), alterations of the iridocorneal angle.

Accidents, Home↗
PubMed1999

Differential regulation of the expression of nucleotide pyrophosphatases/phosphodiesterases in rat liver.

We propose the name nucleotide pyrophosphatases/phosphodiesterases (NPP) for the enzymes that release nucleoside-5'-monophosphates from various pyrophosphate and phosphodiester bonds. Three structurally related mammalian NPPs are known, i.e. NPPalpha (autotaxin), NPPbeta (B10/gp130RB13-6) and NPPgamma (PC-1). We report here that these isozymes have a distinct tissue distribution in the rat but that they are all three expressed in hepatocytes. In FAO rat hepatoma cells only the level of NPPgamma was stimulated by TGF-beta1. In rat liver, the concentration of the transcripts of all three isozymes was found to increase manyfold during the first weeks after birth, but the increased expression of the NPPalpha mRNA was transient. The level of the NPP transcripts transiently decreased after hepatectomy, but NPPalpha mRNA was also lost after sham operation, which suggests that it may belong to the negative acute-phase proteins. The loss of the beta- and gamma-transcripts after hepatectomy was not due to a decreased NPP gene transcription or an increased turnover of the mature transcripts. However, hepatectomy also caused a similar loss of the nuclear pool of the NPPbeta and NPPgamma mRNAs. We conclude that a deficient processing and/or an increased turnover of the NPP pre-mRNAs underlies the hepatectomy-induced decrease of the beta- and gamma-transcripts. A similar loss of nuclear NPPgamma mRNA was also noted after treatment with cycloheximide, indicating that protein(s) with a high turnover control the stability and/or processing of the immature NPPgamma transcript.

Age Factors↗
PubMed1999

An ecto-nucleotide pyrophosphatase is one of the main enzymes involved in the extracellular metabolism of ATP in rat C6 glioma.

The presence of a nucleotide pyrophosphatase (EC 3.6.1.9) on the plasma membrane of rat C6 glioma has been demonstrated by analysis of the hydrolysis of ATP labeled in the base and in the alpha- and gamma-phosphates. The enzyme degraded ATP into AMP and PPi and, depending on the ATP concentration, accounted for approximately 50-75% of the extracellular degradation of ATP. The association of the enzyme with the plasma membrane was confirmed by ATP hydrolysis in the presence of a varying concentration of pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), a membrane-impermeable inhibitor of the enzyme. PPADS concentration above 20 microM abolished the degradation of ATP into AMP and PPi. The nucleotide pyrophosphatase has an alkaline pH optimum and a Km for ATP of 17 +/- 5 microM. The enzyme has a broad substrate specificity and hydrolyzes nucleoside triphosphates, nucleoside diphosphates, dinucleoside polyphosphates, and nucleoside monophosphate esters but is inhibited by nucleoside monophosphates, adenosine 3',5'-bisphosphate, and PPADS. The substrate specificity characterizes the enzyme as a nucleotide pyrophosphatase/phosphodiesterase I (PD-I). Immunoblotting and autoadenylylation identified the enzyme as a plasma cell differentiation antigen-related protein. Hydrolysis of ATP terminates the autophosphorylation of a nucleoside diphosphate kinase (NDPK/nm23) detected in the conditioned medium of C6 cultures. A function of the pyrophosphatase/PD-I and NDPK in the purinergic and pyrimidinergic signal transduction in C6 is discussed.

Adenosine Triphosphate↗
PubMed1999

[Artificial drainage devices in glaucoma].

During the last two decades, glaucoma drainage devices (GDD) have been increasingly applied to the treatment of complicated glaucoma in which standard surgical therapy has failed. Most GDD's consist of a segment of silicone rubber attached to a rigid plastic or flexible rubber explant and evolved from the Molteno glaucoma implant, on which clinical studies first appeared in 1969. GDD's should be reserved for the most difficult cases because of the difficulty of the surgical procedure and the complications that can attend their use.

Glaucoma↗
PubMed1999

[The use of antimetabolites in the treatment of glaucoma].

Many adjunctive therapies have been proposed to increase the success and prevent or reduce the incidence of complications associated with filtering surgery. Intraoperative or postoperative use of an antimetabolite has found a place as adjunctive therapy for eyes with otherwise pour prognosis following glaucoma filtering surgery.

Antimetabolites↗