Biomedical subjects

Maria C Rojas

Publications and source records attributed to Maria C Rojas.

7 recordsLinked to original sources

PubMed2004

The NADPH-cytochrome P450 reductase gene from Gibberella fujikuroi is essential for gibberellin biosynthesis.

The fungus Gibberella fujikuroi is used for the commercial production of gibberellins (GAs), which it produces in very large quantities. Four of the seven GA biosynthetic genes in this species encode cytochrome P450 monooxygenases, which function in association with NADPH-cytochrome P450 reductases (CPRs) that mediate the transfer of electrons from NADPH to the P450 monooxygenases. Only one cpr gene (cpr-Gf) was found in G. fujikuroi and cloned by a PCR approach. The encoded protein contains the conserved CPR functional domains, including the FAD, FMN, and NADPH binding motifs. cpr-Gf disruption mutants were viable but showed a reduced growth rate. Furthermore, disruption resulted in total loss of GA(3), GA(4), and GA(7) production, but low levels of non-hydroxylated C(20)-GAs (GA(15) and GA(24)) were still detected. In addition, the knock-out mutants were much more sensitive to benzoate than the wild type due to loss of activity of another P450 monooxygenase, the detoxifying enzyme, benzoate p-hydroxylase. The UV-induced mutant of G. fujikuroi, SG138, which was shown to be blocked at most of the GA biosynthetic steps catalyzed by P450 monooxygenases, displayed the same phenotype. Sequence analysis of the mutant cpr allele in SG138 revealed a nonsense mutation at amino acid position 627. The mutant was complemented with the cpr-Gf and the Aspergillus niger cprA genes, both genes fully restoring the ability to produce GAs. Northern blot analysis revealed co-regulated expression of the cpr-Gf gene and the GA biosynthetic genes P450-1, P450-2, P450-4 under GA production conditions (nitrogen starvation). In addition, expression of cpr-Gf is induced by benzoate. These results indicate that CPR-Gf is the main but not the only electron donor for several P450 monooxygenases from primary and secondary metabolism.

Base Sequence↗

PubMed2004

Treatment of epithelial ingrowth after laser in situ keratomileusis with mechanical debridement and flap suturing.

OBJECTIVE: To evaluate the efficacy and safety of mechanical debridement and suturing of the laser in situ keratomileusis (LASIK) flap in the treatment of clinically significant epithelial ingrowth after LASIK. METHODS: In a retrospective study, 20 eyes (n = 19 patients) in which clinically significant epithelial ingrowth developed after LASIK were treated with lifting of the flap, scraping of the epithelial ingrowth, and flap suturing. Primary outcome measurements including recurrence of ingrowth, uncorrected visual acuity (VA), manifest refraction, best spectacle-corrected VA, and complications were evaluated at the last postoperative examination. RESULTS: At the last postoperative examination (mean +/- SD, 10.5 +/- 14.3 months; range, 1.5-64 months), 100% of eyes had no recurrence of clinically significant epithelial ingrowth. The uncorrected VA changed from 20/20 or better in 7 eyes (35%) and 20/40 or better in 15 eyes (75%) preoperatively to 20/20 or better in 9 eyes (45%) and 20/40 or better in 16 eyes (80%) at the last follow-up examination. There was no significant change in the mean logarithm of the minimum angle of resolution (logMAR) uncorrected VA before (mean +/- SD, 0.3 +/- 0.5; range, -0.1 to 1.7) and after surgery (mean +/- SD, 0.2 +/- 0.4; range, -0.1 to 1.7) (P =.40). Mean +/- SD spherical equivalent changed from -0.21 +/- 0.82 diopters (D) (range, -1.25 to 1.00 D) preoperatively to -0.53 +/- 0.89 D (range, -2.50 to 0.38 D) at last follow-up (P =.30). No eyes lost 2 or more lines of best spectacle-corrected VA, and there were no complications associated with the treatment. CONCLUSIONS: Suturing the LASIK flap in addition to mechanical debridement of epithelial ingrowth is a safe and effective treatment for clinically significant epithelial ingrowth after LASIK.

Adult↗

PubMed2004

Analysis of the efficacy, predictability, and safety of LASEK for myopia and myopic astigmatism using the Technolas 217 excimer laser.

PURPOSE: To evaluate the efficacy, predictability, and safety of laser-assisted subepithelial keratectomy (LASEK) for the treatment of myopia and myopic astigmatism. SETTING: Stanford University Eye Laser Center, Stanford, California, USA. METHODS: This retrospective analysis comprised 102 eyes that had LASEK for myopia using the Bausch & Lomb Technolas 217 excimer laser. Primary outcome variables including uncorrected visual acuity (UCVA), best spectacle- corrected visual acuity (BSCVA), manifest refraction, and complications were evaluated at 3, 6, and 12 months. Vector analysis was performed on eyes that received astigmatic correction. RESULTS: The mean spherical equivalent was -7.03 diopters (D) +/- 2.61 (SD) preoperatively, +0.19 +/- 0.64 D at 3 months, +0.23 +/- 0.82 D at 6 months, and +0.03 +/- 0.63 D at 12 months (P<.001). At 3, 6, and 12 months, the UCVA was 20/20 or better in 66%, 67%, and 83% of eyes, respectively, and 20/40 or better in 98%, 99%, and 100%; 74%, 70%, and 83%, respectively, were within +/-0.5 D of emmetropia, and 89%, 86%, and 97%, respectively, were within +/-1.0 D. No eye lost more than 2 lines of BSCVA. At 3, 6, and 12 months, 10.0%, 8.7%, and 0% of eyes, respectively, had trace corneal haze. Vector analysis found a success rate of approximately 78% to 80% in achieving the astigmatic surgical correction at the 3 postoperative visits. CONCLUSIONS: Laser-assisted subepithelial keratectomy was an effective, predictable, and safe procedure for the treatment of myopia and myopic astigmatism. Further studies are needed to determine the role of LASEK in the refractive surgery spectrum.

Adult↗

PubMed2002

Phototherapeutic keratectomy for anterior basement membrane dystrophy after laser in situ keratomileusis.

OBJECTIVE: To evaluate the efficacy and safety of phototherapeutic keratectomy (PTK) in the treatment of symptomatic anterior basement membrane dystrophy following laser in situ keratomileusis (LASIK). METHODS: In a retrospective study, 10 eyes of 10 patients that developed symptomatic anterior basement membrane dystrophy following LASIK for myopia were treated with PTK using the VISX S2 (VISX Inc, Santa Clara, Calif) excimer laser. Primary outcome measurements including corneal clarity, resolution of symptoms, uncorrected visual acuity (UCVA), manifest refraction, best spectacle-corrected visual acuity (BSCVA), and complications were evaluated preoperatively, 1 day postoperatively, and at the last postoperative follow-up visit. RESULTS: At the last follow-up visit (mean [SD], 8.8 [5.5] months; range, 4-22 months), 100% of the eyes had clear corneas with no evidence of anterior basement membrane dystrophy, and all eyes were asymptomatic. Mean spherical equivalent changed from -0.75 (0.99) diopters (D) (range, -2.75 to +0.25 D) preoperatively to -0.51 (0.80) D (range, -1.63 to +1.00 D) at the last follow-up visit (P =.64). Uncorrected visual acuity improved from 20/20 or better in 1 eye (10%) and 20/40 or better in 5 eyes (50%) preoperatively to 20/20 or better in 5 eyes (50%) and 20/40 or better in 7 eyes (70%) postoperatively. No eyes lost lines of BSCVA, 2 eyes gained 1 line, 2 eyes gained 2 lines, and 1 eye gained 4 lines. There was a statistically significant improvement in mean logMAR BSCVA postoperatively, improving from 0.06 (0.16) (range, -0.1 to +0.3) to -0.08 (0.07) (range, -0.1 to +0.1) (P =.04). Postoperative complications included diffuse lamellar keratitis that resolved after treatment without sequelae (20%) and induced myopia exceeding -1.50 D (10%). CONCLUSION: Phototherapeutic keratectomy for the treatment of symptomatic anterior basement membrane dystrophy following LASIK treatment is safe and effective.

Adult↗

PubMed2002

Goniotomy for glaucoma secondary to chronic childhood uveitis.

PURPOSE: To evaluate the safety and efficacy of standard goniotomy surgery for young patients with refractory glaucoma associated with chronic childhood uveitis. DESIGN: Interventional case series. METHODS: We retrospectively reviewed all goniotomies performed at our institution for patients with a diagnosis of refractory glaucoma associated with chronic childhood uveitis from 1994 to 2000 (this was our first-line surgery for such patients during these years). Uveitis was medically controlled in all cases for at least 6 weeks before surgery. The main outcome measure was time after surgery without failure. Success was defined as final intraocular pressure (IOP) or=6 months or until surgical failure. RESULTS: Nineteen goniotomies were performed on 16 eyes (12 patients). Diagnoses included uveitic glaucoma associated with juvenile rheumatoid arthritis, sarcoidosis, and idiopathic uveitis. The mean patient age at first goniotomy was 15.3 years (range, 6.5-30), with mean follow-up 32.4 months (range, 6-84). Cases included were phakic (10 eyes), aphakic (four eyes), and pseudophakic (two eyes). The mean preoperative IOP was 32.3 +/- 4.6 mm Hg. Surgical success was achieved in 12 of 16 (75%) eyes with a mean postoperative IOP of 12 +/- 2.5 mm Hg for these eyes (mean IOP reduction, 20.0 mm Hg, P <.0001). In 10 of 16 eyes (60%), surgical success was achieved after a single goniotomy. Uveitis was stable in all patients after the early post-operative period. Successful eyes used, on average, 1.4 +/- 1.1 glaucoma medications after goniotomy. Complications were mild and included transient hyphema in nine cases (56%) and worsening of a preexisting cataract in a single case (6%). CONCLUSIONS: Goniotomy represents a safe and effective first-line surgery for young patients with refractory glaucoma associated with chronic uveitis, although the majority of patients require glaucoma medication after the procedure.

Adolescent↗

PubMed2002

Laser in situ keratomileusis enhancement for consecutive hyperopia after myopic overcorrection.

PURPOSE: To assess the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) for the treatment of consecutive hyperopia after myopic LASIK. SETTING: Stanford University School of Medicine, Stanford, California, USA. METHODS: In a retrospective study, 36 eyes of 30 patients with consecutive hyperopia after myopic LASIK had LASIK retreatment using the VISX S2 excimer laser. Primary outcome variables including uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, complications, and vector analysis were evaluated preoperatively and 1 day and 3 months postoperatively. RESULTS: The mean spherical equivalent decreased from +1.52 diopters (D) +/- 0.55 (SD) (range +0.63 to +2.63 D) preoperatively to -0.10 +/- 0.52 D (range -1.25 to +1.50 D) 3 months after retreatment. The UCVA was 20/20 or better in 24 eyes (66.7%) and 20/40 or better in 34 eyes (94.4%). Twenty eyes (55.5%) were within +/-0.5 D of the intended correction and 34 eyes (94.4%), within +/-1.0 D. No eye lost 2 or more lines of BSCVA. One eye (2.8%) developed diffuse lamellar keratitis that resolved without sequelae, and 2 eyes (5.6%) developed nonprogressive epithelial ingrowth that did not require removal. CONCLUSIONS: Laser in situ keratomileusis retreatment for consecutive hyperopia following myopic LASIK was an effective, predictable, and safe procedure. Long-term follow-up is needed to assess stability.

Adult↗

PubMedDate not supplied

Comparison of videokeratographic functional optical zones in conductive keratoplasty and laser in situ keratomileusis for hyperopia.

PURPOSE: To compare the videokeratographic functional optical zone of eyes treated with conductive keratoplasty to eyes treated with laser in situ keratomileusis (LASIK) for hyperopia. METHODS: Sixteen eyes treated with conductive keratoplasty for hyperopia were retrospectively evaluated to determine the size of the videokeratographic functional optical zone. The functional optical zone of these eyes was compared to the functional optical zone of 16 eyes that underwent LASIK for hyperopia with the VISX S2 excimer laser, for comparable amounts of hyperopia. The functional optical zone was measured at the edge of central corneal steepening and paracentral flattening on videokeratography 3 to 6 months after surgery. RESULTS: The functional optical zone after surgery measured an average of 5.6 mm horizontally and 5.6 mm vertically in the conductive keratoplasty eyes, and 4.7 mm horizontally and 5.1 mm vertically in the hyperopic LASIK eyes (P<.001 and P<.005). The mean functional optical zone area was 31.1 mm2 in the conductive keratoplasty eyes and 24.6 mm2 in the hyperopic LASIK eyes (P<.001). The functional optical zone created by conductive keratoplasty had more uniform central steepening and less peripheral blending than the functional optical zone created by hyperopic LASIK. CONCLUSION: Conductive keratoplasty was effective at creating central steepening in the cornea. The functional optical zone resulting from conductive keratoplasty was significantly larger than that obtained with hyperopic LASIK using the VISX S2 excimer laser.

Adult↗