Biomedical subjects

Ramesh C Tripathi

Publications and source records attributed to Ramesh C Tripathi.

5 recordsLinked to original sources

PubMed2004

Trabecular cell expression of fibronectin and MMP-3 is modulated by aqueous humor growth factors.

We investigated the mRNA and protein expression of fibronectin and stromelysin-1 (matrix metalloproteinase-3, MMP-3) by trabecular cells treated with growth factors present in primary and secondary aqueous humors. Serum-deprived trabecular cells were incubated for 48 hr or 7 days in medium containing either primary or secondary aqueous humor growth factors or in serum-free medium. We extracted total RNA, performed reverse transcription-polymerase chain reaction using primer pairs for fibronectin, stromelysin-1 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and quantified the products. We utilized Western blotting to detect and quantify fibronectin and stromelysin-1 protein. Compared to controls, expression of fibronectin mRNA by trabecular cells was increased by 50 and 100% after incubation in primary aqueous humor growth factors for 48 hr or 7 days, respectively, and 50 and 130% after incubation in secondary aqueous humor growth factors. Stromelysin-1 mRNA expression was decreased by 25 and 50% after incubation in primary aqueous humor growth factors for 48 hr or 7 days, respectively, and 80 and 85% after incubation for 48 hr or 7 days, respectively, in secondary aqueous humor growth factors. Fibronectin protein increased 3.5-fold and 6-fold after incubation for 48 hr with primary or secondary aqueous humor growth factors, respectively; after 7 days, the level increased 4- and 7-folds, respectively. Stromelysin-1 protein was not detectable by western blotting. The up-regulation of fibronectin mRNA by trabecular cells exposed to growth factors present in secondary aqueous humor augmented by the down-regulation of stromelysin-1 mRNA contributed to the accumulation of fibronectin. Our findings open the possibility that induction of stromelysin-1 gene expression in the trabecular meshwork of glaucomatous eyes could effectively reduce buildup of fibronectin in the aqueous outflow pathway to decrease outflow resistance in glaucomatous states of the eye.

Animals↗

PubMed2003

Evaluation and comparison of lens and peripheral retinal relationships with the use of endolaser probe and newly designed curved vitrectomy probe.

OBJECTIVE: To evaluate and compare the relationships between the posterior surface of the crystalline lens and peripheral retina with the use of curved vitrectomy instruments. MATERIALS AND METHODS: Specially designed curved endolaser and vitrectomy probes were compared with conventional straight probes through sclerotomy sites at 3.0 mm and 4.0 mm, in 12 fresh cadaver phakic eyes. For the safety profile, the perpendicular distance between the probe oriented toward a reference point on the retina and the midpoint of the posterior surface of the lens was measured. For access to the retinal periphery, the distance between the ora serrata and the most peripheral accessible point on the retina without touching the crystalline lens with the probes was measured. RESULTS: The perpendicular distance between the probe and posterior surface of the lens increased, and the ability of the probe to reach the most peripheral accessible point on the retina improved with the curved probes as compared with straight probes. CONCLUSIONS: Curved probes can access the peripheral retina and ora serrata with lesser possibility to injure the crystalline lens during vitreous surgery than the standard straight probes.

Equipment Design↗

PubMed2003

Drug-induced glaucomas: mechanism and management.

Glaucoma comprises a heterogeneous group of diseases that have in common a characteristic optic neuropathy and visual field defects, for which elevated intraocular pressure is the major risk factor. The level of intraocular pressure within the eye depends on the steady state of formation and drainage of the clear watery fluid, called the aqueous humour, in the anterior chamber of the eye. An obstruction in the circulatory pathway of aqueous humour causes an elevation in intraocular pressure. Because intraocular pressure is the most modifiable parameter, therapeutic measures (medical and surgical) are aimed at reducing the pressure to protect against optic nerve damage. Glaucomatous optic neuropathy results from degeneration of the axonal nerve fibres in the optic nerve and death of their cell bodies, the retinal ganglion cells. Clinical examination of the optic nerve head or disc and the peripapillary nerve fibre layer of the retina reveals specific changes, and the resulting visual field defects can be documented by perimetry. Glaucoma can be classified into four main groups: primary open-angle glaucoma; angle-closure glaucoma; secondary glaucoma; and developmental glaucoma. Drug-induced glaucoma should be considered as a form of secondary glaucoma because it is brought about by specific systemic or topical medications. Although there is a high prevalence of glaucoma worldwide, the incidence of drug-induced glaucoma is uncertain. Drugs that cause or exacerbate open-angle glaucoma are mostly glucocorticoids. Several classes of drugs, including adrenergic agonists, cholinergics, anticholinergics, sulpha-based drugs, selective serotonin reuptake inhibitors, tricyclic and tetracyclic antidepressants, anticoagulants and histamine H(1) and H(2) receptor antagonists, have been reported to induce or precipitate acute angle-closure glaucoma, especially in individuals predisposed with narrow angles of the anterior chamber. In some instances, bilateral involvement and even blindness have occurred. In this article, the mechanism and management of drug-induced glaucomatous disease of the eye are emphasised. Although the product package insert may mention glaucoma as a contraindication or as an adverse effect, the type of glaucoma is usually not specified. Clinicians should be mindful of the possibility of drug-induced glaucoma, whether or not it is listed as a contraindication and, if in doubt, consult an ophthalmologist.

Drug-Related Side Effects and Adverse Reactions↗

PubMedDate not supplied

Pars plana modified Baerveldt implant versus neodymium:YAG cyclophotocoagulation in the management of neovascular glaucoma.

OBJECTIVE: To determine the relative effectiveness of neodymium:YAG cyclophotocoagulation (NCYC) and pars plana modified Baerveldt implant (PPBI) surgery on intraocular pressure (IOP) control in eyes with neovascular glaucoma (NVG). PARTICIPANTS: In this retrospective comparative group study, 30 patients with NVG treated with contact NCYC were compared with 18 patients who underwent PPBI. Patients groups were not statistically dissimilar with respect to the underlying disorder-causing angle and iris neovascularization, intraocular pressure, and patient's age. RESULTS: During a follow up of 6 months, an IOP control of > or = 6 and < or = 21 mm Hg was achieved in 23 eyes (76.6%) treated with NCYC compared with 17 eyes (94.4%) receiving PPBI (P = 0.13). Among eyes that had unsuccessful outcome in both groups, the proportions with persistently high IOP or hypotony were greater in the NCYC group than in the PPBI group. Based on our criteria, the cumulative proportion of failure in the NCYC group was 23.3% at 6 months as compared to 5.6% in the PPBI group. Seven eyes (23.3%) in the NCYC group lost light perception versus 1 eye (5.6%) in the PPBI group. The incidence of postoperative choroidal effusion (36%) was higher in the PPBI group. CONCLUSIONS: This study suggests that in the management of NVG, PPBI surgery more frequently controls IOP in a medically acceptable range with less hypotony and greater preservation of visual acuity than NCYC.

Adult↗

PubMedDate not supplied

A curved vitrectomy probe.

A curved vitrectomy probe for better accessibility of the peripheral retina in phakic eyes is described. The specially designed curved vitrectomy probe has a 20-gauge pneumatic cutter. The radius of curvature at the shaft is 19.4 mm and it is 25 mm long. The ora serrata is accessed through a 3.0- or 4.0-mm sclerotomy in phakic eyes without touching the crystalline lens. Use of this instrument avoids inadvertent trauma to the clear lens in phakic eyes requiring vitreous base excision. This curved vitrectomy instrument complements wide-angle viewing systems and endoscopes for safe surgical treatment of peripheral retinal pathology in phakic eyes.

Equipment Design↗