Biomedical subjects

Y K Weaver

Publications and source records attributed to Y K Weaver.

5 recordsLinked to original sources

PubMed1999

Conjunctival advancement for late-onset filtering bleb leaks: indications and outcomes.

OBJECTIVE: To determine the indications and outcome of conjunctival advancement surgery for late-onset filtering bleb leaks. PATIENTS AND METHODS: Retrospective medical record review of a consecutive case series of all patients who underwent conjunctival advancement surgery for persistent late-onset glaucoma filtering bleb leaks at a tertiary referral center between December 1, 1985, and April 30, 1997. MAIN OUTCOME MEASURES: Indications for surgery, preoperative and postoperative intraocular pressure (IOP), visual acuity, status of bleb leak, and need for reinstitution of medical therapy or reoperation for glaucoma. RESULTS: Twenty-six eyes of 26 patients were analyzed. Complications from bleb leaks that necessitated surgical intervention included chronic ocular hypotony (n = 21), decreased visual acuity (n = 9), bleb-related infection (n = 11), hypotony maculopathy (n = 4), corneal edema with folds (n = 7), choroidal effusion (n = 3), and persistent shallow anterior chamber (n = 3). The mean +/- SD preoperative IOP was 5.7 +/- 4.9 mm Hg (range, 0-16 mm Hg). After a follow-up of 19.6 +/- 22.6 months, the IOP was 14.2 +/- 4.1 mm Hg for patients taking 1.1 +/- 1.3 glaucoma medications (all data given as mean +/- SD). Twelve patients (46%) had early-onset bleb leaks after revision, of which 7 (27%) closed spontaneously and 5 (19%) required resuturing. Two patients (8%) had a persistent bleb leak throughout the follow-up period. Thirteen patients (50%) required reinstitution of medical therapy during the follow-up period, and 2 (8%) required a reoperation for glaucoma for uncontrolled IOP. CONCLUSIONS: Conjunctival advancement is a successful procedure for closing late-onset filtering bleb leaks. Some patients require suturing in the early postoperative period, but most patients eventually obtain permanent closure of the leak. Patients should be counseled of the possibility of requiring medical or surgical intervention for IOP control after revision.

Adolescent↗

PubMed1998

Trabeculectomy function after cataract extraction.

OBJECTIVE: To examine the effect of cataract extraction (CE) after trabeculectomy on intraocular pressure (IOP) control. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: A total of 115 consecutive patients who underwent extracapsular CE (N = 58) or phacoemulsification (N = 57) with intraocular lens (IOL) placement after trabeculectomy were studied. INTERVENTION: Cataract extraction with IOL after trabeculectomy was performed. MAIN OUTCOME MEASURES: Preoperative, intraoperative, and postoperative factors were evaluated for association with loss of IOP control requiring additional medications, bleb needling, or further glaucoma surgery, using Kaplan-Meier survival analysis and Cox multivariate proportional hazards survival regression. RESULTS: After mean postoperative follow-up of 21.1 +/- 14.3 months, additional glaucoma medication or needling of the filtering bleb to maintain IOP control was required in 35 eyes (30.4%) and was significantly associated with intraoperative iris manipulation and early postoperative peak IOP greater than 25 mmHg. Additional glaucoma surgery was eventually required in 11 eyes (9.6%) and was significantly associated with age of 50 years or younger, preoperative IOP greater than 10 mmHg, and early postoperative peak IOP greater than 25 mmHg. The cumulative proportion of patients who did not require reoperation for glaucoma was 93% and 90% at 1 and 2 years, respectively. The mean IOP at last visit had increased 1.6 mmHg above the pre-CE level and did not vary significantly after the first postoperative month. The median interval from CE to the addition of glaucoma medication or bleb needling was 1.6 months (within 3 months in 20 of 33 eyes) and that from nonsurgical intervention to further glaucoma surgery was 3.6 months (before the 7th postoperative month in 6 of 11 eyes). Of 19 eyes with hypotony (IOP < or = 6 mmHg) before CE, 11 eyes remained hypotonous after CE despite an increase in the mean IOP from 4.6 to 7.5 mmHg. CONCLUSIONS: When CE is performed after trabeculectomy, age of 50 years or younger, preoperative IOP greater than 10 mmHg, intraoperative iris manipulation, and early postoperative IOP greater than 25 mmHg are associated with worsened postoperative IOP control. Most bleb failures occur soon after CE. Resolution of pre-existing hypotony after CE is unpredictable.

Adolescent↗

PubMed1994

Intraocular microsurgery with a picosecond Nd:YAG laser.

We investigated the use of picosecond Nd:YAG laser pulses for intraocular microsurgery. With a pulse duration of 100 picoseconds, only 70 microJ of pulse energy is required to consistently produce optical breakdown in the deep vitreous. This pulse energy is nearly two orders of magnitude less than the typical pulse energies used in conventional (nanosecond) photodisruptors. The reduced pulse energy results in a smaller zone of tissue damage, an important consideration when operating close to the retina or other sensitive ocular structures. Efficient cutting action is achieved by applying multiple pulses at a moderately high repetition rate of 50-200 Hz. An in vitro model was developed to assess axial confinement of picosecond photodisruption. In vivo vitreous membrane surgery was performed in experimental rabbit eyes to demonstrate a potential clinical application of picosecond laser-induced optical breakdown.

3T3 Cells↗

PubMed1991

Cytoplasmic tail deletion converts membrane immunoglobulin to a phosphatidylinositol-linked form lacking signaling and efficient antigen internalization functions.

Membrane-bound immunoglobulin (mIg) is the antigen receptor on B lymphocytes mediating early events in antigen presentation and signal transduction. Wild-type human mIgM constructs transfected into the murine B-cell lymphoma A20 are expressed as transmembrane proteins with antigen presentation and signaling functions comparable to the endogenous mIgG2A; the transfected wild-type mIgM is internalized rapidly after anti-Ig cross-linking. Transfected constructs lacking the normal three-amino acid cytoplasmic tail are expressed exclusively as phosphatidylinositol-linked proteins, lack both antigen presentation and signal transduction functions, and are internalized slowly following anti-Ig binding. The molecular mass of the cytoplasmic tail-deleted phosphatidylinositol-linked Ig molecule is consistent with cleavage of the transmembrane residues during processing. Cytoplasmic domains may therefore regulate the mode of expression of membrane proteins and thereby influence their functional capabilities.

Animals↗

PubMed1990

Mutations of immunoglobulin transmembrane and cytoplasmic domains: effects on intracellular signaling and antigen presentation.

The membrane-bound form of immunoglobulin serves as an antigen-specific receptor for B cells mediating signal transduction and antigen presentation. We have developed an assay that reconstitutes both these physiologic responses with respect to the antigen phosphorylcholine. By introducing specific mutations in the human Ig mu chain gene, we have shown that certain transmembrane residues and the short cytoplasmic domain are crucial for these two activities. Moreover, elimination of a single transmembrane hydroxyl group severely inhibits antigen presentation without affecting signal transduction, suggesting that these two functions are mediated by different protein interactions.

Amino Acid Sequence↗