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Biomedical subjects

D Litoff

Publications and source records attributed to D Litoff.

10 recordsLinked to original sources
PubMed1997

The effects of donor age on the outcome of penetrating keratoplasty in adults.

OBJECTIVE: The purpose of the study is to determine whether there is a higher incidence of complications in adult patients receiving corneas from pediatric donors compared to those receiving corneas from adult donors. DESIGN: The design is a follow-up of two matched cohorts. PARTICIPANTS: The outcome of penetrating keratoplasty in 29 adult patients (age 20 years of age and older) receiving pediatric donor corneas (range, 0-5 years) was compared to that of 29 control patients matched for recipient age and diagnosis who received adult donor corneas (range, 40-70 years). INTERVENTION: Chart review was performed. MAIN OUTCOME MEASURES: Graft rejection, postoperative keratometry, postoperative refractive cylinder, postoperative intraocular pressure, and graft failure due to rejection were measured. RESULTS: One or more allograft reactions occurred in 11 (37.9%) of 29 patients who received pediatric donor corneas compared to 2 (6.9%) of 29 patients who received adult donor corneas (P = 0.005, chi-square). There were a total of 20 rejection episodes in patients receiving pediatric donor corneas compared to a total of 5 rejection episodes in patients receiving adult donor corneas. The average postoperative keratometry was 46.1 diopters for the pediatric donor group and 44.0 diopters for the adult donor group (P = 0.03). There was no statistically significant difference in average refractive cylinder (P = 1.0), intraocular pressure (P = 0.26), or the incidence of graft failure due to rejection (P = 1.0) between the two groups. The average follow-up time for clear grafts was 58.3 months in the pediatric donor group and 59.9 months in the adult donor group. CONCLUSIONS: The incidence of allograft reactions and the postoperative corneal curvature is greater in adult eyes undergoing penetrating keratoplasty with young donor corneas compared to those undergoing penetrating keratoplasty with older donor corneas. There was no difference in the incidence of graft failure due to rejection between the two groups.

Adult↗
PubMed1992

Argon laser fenestration of a Softperm contact lens.

Contact lens fenestration can increase tear exchange. We describe a case in which a patient with 15 D of against-the-rule astigmatism was fit with a Softperm contact lens but was unable to wear it for more than 1 hour because of corneal edema. After fenestrating the Softperm lens with an argon laser the patient was able to wear her lens for 10 hours without signs of corneal decompensation.

Aged↗
PubMed1987

Extracapsular cataract extraction and posterior chamber intraocular lens implantation combined with trabeculectomy in patients with glaucoma.

We reviewed 75 consecutive cases of extracapsular cataract extraction and posterior chamber intraocular lens implantation combined with trabeculectomy in 69 patients with glaucoma. The mean preoperative intraocular pressure was 19.3 mm Hg on an average of 2.3 glaucoma medications. Visual acuity improved in 58 eyes (77%) at two months, with an average improvement of 3.3 and 3.6 lines at two and 12 months, respectively. Of the 75 eyes, 49 (65%) achieved a visual acuity of 20/40 or better; three patients (4%) had further deterioration in vision at the completion of follow-up because of progressive glaucoma or macular disease. Postoperatively, the average intraocular pressure was 3.8 and 3.0 mm Hg lower than the preoperative level at two and 12 months (P less than .001) on 0.63 and 0.79 glaucoma medications, respectively. However, 27 (36%) of the 75 eyes had a recorded intraocular pressure greater than 30 mm Hg and 30 (40%) had a pressure 7 mm Hg or more above their preoperative level during the first six months after surgery. Despite improved long-term control of intraocular pressure, detectable conjunctival filtering blebs were present in only 31 (41%) of 75 eyes at two months and in seven (12%) of 56 eyes at 12 months. Hyphema occurred in 34 (45%) of the cases.

Cataract↗
PubMed1985

Receptor function of mouse sperm surface galactosyltransferase during fertilization.

Past studies from this laboratory have suggested that mouse sperm binding to the egg zona pellucida is mediated by a sperm galactosyltransferase (GalTase), which recognizes and binds to terminal N-acetylglucosamine (GlcNAc) residues in the zona pellucida (Shur, B. D., and N. G. Hall, 1982, J. Cell Biol. 95:567-573; 95:574-579). We now present evidence that directly supports this mechanism for gamete binding. GalTase was purified to homogeneity by sequential affinity-chromatography on GlcNAc-agarose and alpha-lactalbumin-agarose columns. The purified enzyme produced a dose-dependent inhibition of sperm binding to the zona pellucida, relative to controls. To inhibit sperm/zona binding, GalTase had to retain its native conformation, since neither heat-inactivated nor Mn++-deficient GalTase inhibited sperm binding. GalTase inhibition of sperm/zona binding was not due to steric blocking of an adjacent sperm receptor on the zona, since GalTase could be released from the zona pellucida by forced galactosylation with UDPGal, and the resulting galactosylated zona was still incapable of binding sperm. In control experiments, when UDPGal was replaced with the inappropriate sugar nucleotide, UDPglucose, sperm binding to the zona pellucida remained normal after the adsorbed GalTase was washed away. The addition of UDPGal produced a dose-dependent inhibition of sperm/zona binding, and also dissociated preformed sperm/zona adhesions by catalyzing the release of the sperm GalTase from its GlcNAc substrate in the zona pellucida. Under identical conditions, UDP-glucose had no effect on sperm binding to the zona pellucida. The ability of UDPGal to dissociate sperm/zona adhesions was both time- and temperature-dependent. UDPGal produced nearly total inhibition of sperm/zona binding when the zonae pellucidae were first galactosylated to reduce the number of GalTase binding sites. Finally, monospecific anti-GalTase IgG and its Fab fragments produced a dose-dependent inhibition of sperm/zona binding and concomitantly blocked sperm GalTase catalytic activity. Preimmune IgG or anti-mouse brain IgG, which also binds to the sperm surface, had no effect. The sperm GalTase was localized by indirect immunofluorescence to a discrete plasma membrane domain on the dorsal surface of the anterior head overlying the intact acrosome. These results, along with earlier studies, show clearly that sperm GalTase serves as a principal gamete receptor during fertilization.

Acetylglucosaminidase↗
PubMedDate not supplied

The PAR Technology Corneal Topography System.

BACKGROUND: Computer-assisted videokeratography has emerged as a useful clinical and research tool. All of the currently available commercial units utilize a modified placido disk image and require a smooth reflective surface. The PAR Technology Corneal Topography System (PAR CTS) is a prototype of a new computer-assisted corneal imaging device. The system produces a true topographic map (elevation map) by analyzing a projected grid on the corneal surface, as opposed to a placido disk reflection, and utilizes the technique of raster photogrammetry to define elevation points on the corneal surface. Because the system defines elevation points, not curvature, mathematical modeling is easily accomplished. Current software displays include a true topographic map, a spherical subtraction map in both relative and absolute scales, and a meridian analysis that is adapted to display refractive photoablative surgery. METHODS: We evaluated the accuracy of this device by analyzing three calibrated test spheres (55.76, 42.21, and 33.55 diopters). The test spheres were steel balls coated with a thin white silicone polyester coating that was necessary for grid projection. The test spheres were measured by a Taylor-Hobson contact profilometer possessing submicron accuracy. To determine the reproducibility of the system, three investigators measured three noncalibrated balls (20 mm, 18 mm, and 12 mm). The optical system was purposely decentered and refocused after each reading. RESULTS: Utilizing the CTS custom optics, system accuracy at the 8-millimeter test area was 0.03 (SD 0.03), 0.00, (SD 0.02), and 0.07 (SD 0.01) D respectively. Smaller diameter test areas resulted in a predicted loss of accuracy. Maximum intraobserver variability was 0.09, 0.06, and 0.11 D respectively, and maximum interobserver variability measured 0.18, 0.12, and 0.16 D. CONCLUSIONS: These data demonstrate that the PAR CTS is both highly accurate and reproducible in determining topography of spheres that approximate the curvature of the human cornea.

Algorithms↗