Biomedical subjects

Shilpa A Joshi

Publications and source records attributed to Shilpa A Joshi.

4 recordsLinked to original sources

PubMed2005

Safety and efficacy of phacoemulsification compared with manual small-incision cataract surgery by a randomized controlled clinical trial: six-week results.

OBJECTIVE: To compare the efficacy, safety, and refractive errors of astigmatism after cataract surgery by phacoemulsification and manual small-incision cataract surgery techniques. DESIGN: Masked randomized control clinical trial. PARTICIPANTS: Four hundred eyes of 400 patients, 1:1 randomization with half in each arm of the trial. METHODS: A total of 400 eyes was assigned randomly to either phacoemulsification or small-incision groups after informed consent and were operated on by 4 surgeons. They were masked to the technique of surgery before, during, and after cataract surgery and followed up to 1 year after surgery. The intraoperative and postoperative complications, uncorrected and best-corrected visual acuity, and astigmatism were recorded at 1 and 6 weeks postoperatively. MAIN OUTCOME MEASURES: The proportion of patients achieving visual acuity better than or equal to 6/18 with and without spectacles after cataract surgery in the operated eye up to 6 weeks, postoperative astigmatism, and complications during and after surgery. RESULTS: This article reports clinical outcomes up to 6 weeks. Three hundred eighty-three of 400 (95.75%) patients completed the 1-week follow-up, and 372 of 400 (93%) patients completed the 6-week follow-up. One hundred thirty-one of 192 (68.2%) patients in the phacoemulsification group and 117 of 191 (61.25%) patients in the small-incision group had uncorrected visual acuity better than or equal to 6/18 at 1 week (P = 0.153). One hundred fifty of 185 (81.08%) patients of the phacoemulsification group and 133 of 187 (71.1%) patients of the small-incision group (P = 0.038) were better than or equal to 6/18 at the 6-week follow-up for presenting visual activity. Visual acuity improved to > or = 6/18 with best correction in 182 of 185 patients (98.4%) and 184 of 187 (98.4%) patients (P = 0.549), respectively. Poor outcome (postoperative visual acuity < 6/60) was noted in 1 of 185 (0.5%) in the phacoemulsification group and none in the small-incision group. The mode of astigmatism was 0.5 diopters (D) for the phacoemulsification group and 1.5 D for the small-incision group, and the average astigmatism was 1.1 D and 1.2 D, respectively. There was an intra-surgeon variation in astigmatism. The phacoemulsification group had 7 posterior capsular rents compared with 12 in the small-incision group, but the phacoemulsification group had more corneal edema on the first postoperative day. CONCLUSIONS: Both the phacoemulsification and the small-incision techniques are safe and effective for visual rehabilitation of cataract patients, although phacoemulsification gives better uncorrected visual acuity in a larger proportion of patients at 6 weeks.

Astigmatism↗

PubMed2004

Sculpting the proteome with AAA(+) proteases and disassembly machines.

Machines of protein destruction-including energy-dependent proteases and disassembly chaperones of the AAA(+) ATPase family-function in all kingdoms of life to sculpt the cellular proteome, ensuring that unnecessary and dangerous proteins are eliminated and biological responses to environmental change are rapidly and properly regulated. Exciting progress has been made in understanding how AAA(+) machines recognize specific proteins as targets and then carry out ATP-dependent dismantling of the tertiary and/or quaternary structure of these molecules during the processes of protein degradation and the disassembly of macromolecular complexes.

Adaptor Proteins, Vesicular Transport↗

PubMed2004

Communication between ClpX and ClpP during substrate processing and degradation.

In the ClpXP compartmental protease, ring hexamers of the AAA(+) ClpX ATPase bind, denature and then translocate protein substrates into the degradation chamber of the double-ring ClpP(14) peptidase. A key question is the extent to which functional communication between ClpX and ClpP occurs and is regulated during substrate processing. Here, we show that ClpX-ClpP affinity varies with the protein-processing task of ClpX and with the catalytic engagement of the active sites of ClpP. Functional communication between symmetry-mismatched ClpXP rings depends on the ATPase activity of ClpX and seems to be transmitted through structural changes in its IGF loops, which contact ClpP. A conserved arginine in the sensor II helix of ClpX links the nucleotide state of ClpX to the binding of ClpP and protein substrates. A simple model explains the observed relationships between ATP binding, ATP hydrolysis and functional interactions between ClpX, protein substrates and ClpP.

ATPases Associated with Diverse Cellular Activitie↗

PubMed2003

C-terminal domain mutations in ClpX uncouple substrate binding from an engagement step required for unfolding.

ClpX mediates ATP-dependent denaturation of specific target proteins and disassembly of protein complexes. Like other AAA + family members, ClpX contains an alphabeta ATPase domain and an alpha-helical C-terminal domain. ClpX proteins with mutations in the C-terminal domain were constructed and screened for disassembly activity in vivo. Seven mutant enzymes with defective phenotypes were purified and characterized. Three of these proteins (L381K, D382K and Y385A) had low activity in disassembly or unfolding assays in vitro. In contrast to wild-type ClpX, substrate binding to these mutants inhibited ATP hydrolysis instead of increasing it. These mutants appear to be defective in a reaction step that engages bound substrate proteins and is required both for enhancement of ATP hydrolysis and for unfolding/disassembly. Some of these side chains form part of the interface between the C-terminal domain of one ClpX subunit and the ATPase domain of an adjacent subunit in the hexamer and appear to be required for communication between adjacent nucleotide binding sites.

ATPases Associated with Diverse Cellular Activitie↗