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Biomedical subjects

R F Meyer

Publications and source records attributed to R F Meyer.

At least 19 recordsLinked to original sources
PubMed1992

A randomized, prospective, double-masked clinical trial of Optisol vs DexSol corneal storage media.

We compared Optisol and DexSol, two chondroitin-sulfate-based media for corneal storage at 4 degrees C, by transplanting 31 donor cornea pairs (one cornea stored in Optisol and its mate in DexSol for 20 to 134 hours) into 31 pairs of recipients (62 patients). All grafts were clear 1 year after transplantation except for one primary donor failure (Optisol group). Optisol-stored corneas were significantly thinner than DexSol-stored corneas after cardinal suture placement (0.64 mm vs 0.76 mm) and at the end of surgery (0.69 mm vs 0.78 mm); at all points afterward through 1 year the two groups did not differ. The activity of two lysosomal enzymes released into the media during storage, alpha-mannosidase and alpha-glucosidase, was lower in the Optisol group. Epithelial status and all endothelial morphometric parameters, except the figure coefficient at 1 year, did not differ between the two groups before surgery and 3, 6, and 12 months after surgery. Mean endothelial cell loss at 1 year was 15% for the Optisol group and 21% for the DexSol group (P = .22). Thus, Optisol-stored corneas were thinner during surgery than DexSol-stored corneas and there was less lysosomal enzyme activity in the Optisol medium after tissue storage. There were no significant differences in postoperative clinical or endothelial morphometric parameters, however.

Adult↗
PubMed1992

Secondary localized amyloidosis in interstitial keratitis. Clinicopathologic findings.

Cases of secondary localized corneal amyloidosis have been described in various corneal and ocular inflammations but are believed to occur uncommonly. The authors examined histopathologic specimens from 33 consecutive patients with interstitial keratitis who underwent penetrating keratoplasty for visual rehabilitation. In 11 cases (33%), multiple fusiform deposits of amyloid were identified and confirmed in middle and deep corneal stroma using histochemical staining. Characteristic electron microscopic findings were present in two cases. These results indicate that secondary localized corneal amyloidosis occurs frequently in interstitial keratitis and displays a distinct pattern of deposition.

Aged↗
PubMed1992

A pathogenesis study of foot-and-mouth disease in cattle, using in situ hybridization.

Eight calves were exposed in an aerosol chamber to nebulized foot-and-mouth disease virus. Two control animals were exposed in a similar manner to cell culture media only. Animals were euthanized at intervals and various tissues examined by in situ hybridization using a biotinylated RNA probe corresponding to a portion of the viral gene coding for the polymerase enzyme. By this technique large amounts of viral nucleic acid were found in coronary band, interdigital cleft and tongue as early as six hours postexposure, indicating a very rapid delivery from the portal of entry to the predilection sites for lesion development. This occurred well before the onset of viremia which by virus isolation was not detectable until 30 hours postexposure. The in situ hybridization signal in these tissues decreased in intensity and extent with time to focally positive areas, occasionally surrounding a vesicle. Other epidermal sites not normally thought of as sites for foot-and-mouth lesion development, such as carpus and eyelid, also had some viral nucleic acid detectable at various time intervals. In the lung by in situ hybridization, alveolar septa had viral nucleic acid early in infection (6-18 h postexposure) while later (36-96 h postexposure), the in situ hybridization signal was prominent in alveolar macrophages.

Animals↗
PubMed1991

The effect of allograft rejection after penetrating keratoplasty on central endothelial cell density.

We identified all patients who had undergone penetrating keratoplasty for keratoconus and were being observed longitudinally (N = 174). During the follow-up period, 57 of 174 patients (33%) showed evidence of an allograft rejection episode, which occurred at an average of eight months after the operation. We analyzed specular photographs of the corneal endothelium, taken before and after the first allograft rejection episode. A significant decrease in endothelial cell density was observed (11.8%, P less than .0001). As a control, we analyzed all available specular photographs from patients with keratoconus who showed no evidence of allograft rejection after penetrating keratoplasty. The observed endothelial cell density decrease (11.8%) in patients with keratoconus undergoing allograft rejection exceeded that found in the control subjects (6.8%) during a comparable time period (P = .06). Severe allograft rejection episodes resulted in a decrease in endothelial cell density that exceeded expected loss significantly (14.8% compared with 6.9%, P = .01), whereas mild allograft rejection episodes were not associated with a loss in endothelial cell density exceeding that expected (1.8% compared with 6.5%, P = .34).

Endothelium, Corneal↗
PubMed1991

Implantation of Kelman-style, open-loop anterior chamber lenses during keratoplasty for aphakic and pseudophakic bullous keratopathy. A comparison with iris-sutured posterior chamber lenses.

The clinical and specular microscopic results of 40 cases (39 patients) of penetrating keratoplasty during which a Kelman-style anterior chamber intraocular lens was implanted were reviewed retrospectively. Thirty-one pseudophakic eyes received an intraocular lens exchange and nine aphakic eyes received a secondary intraocular lens. Postoperative follow-up averaged 24.5 months (range, 3 to 51 months). At 1, 2, and 3 years after keratoplasty, 39.3%, 63.2%, and 63.6% of eyes, respectively, had visual acuities of 20/40 or better. Ninety-five percent of the grafts remained clear. Causes of poor postoperative visual acuity included cystoid macular edema (32.5%), new glaucoma (22.5%), and age-related macular degeneration (10.0%). Other causes were endothelial rejection leading to graft failure, corneal ulceration, and retinal detachment. Corneal endothelial cell loss by specular microscopy was 11.5% at 1 years, 21.3% at 2 years, and 25.0% at 3 years. These results were compared with cell loss associated with iris-sutured posterior chamber lenses in penetrating keratoplasty. Visual outcomes and complication rates were similar between these two methods; however, the endothelial attrition at 1 and 2 years for the sutured posterior chamber lens was greater than that of the Kelman anterior chamber lens.

Adult↗
PubMed1991

A preliminary study of the pathogenesis of foot-and-mouth disease virus using in situ hybridization.

Five adult guinea pigs were inoculated intraepithelially in the right hindfoot pad with foot-and-mouth disease virus. Animals were euthanatized with carbon dioxide at 4, 10, 24, 48, and 72 hours post-inoculation. Generalized disease developed in the guinea pigs, as evidenced by depression and inappetance by 24 hours post-inoculation and by the formation of vesicles in the noninoculated hindfoot pad by 48 hours post-inoculation. By in situ hybridization, using a 500 base pair biotinylated RNA probe, viral nucleic acid was detected in the noninoculated fore- and hindfoot pads as early as 10 hours post-inoculation, well before any pathologic changes associated with foot-and-mouth disease virus infection were detected. These tissues remained consistently positive for the presence of viral nucleic acid up to the end of the experiment. At this time, in the forefoot pad, even though virus had first been detected with certainty in that tissue 62 hours previously, there was still no microscopic evidence of foot-and-mouth disease virus-induced damage in the histologic section. Similarly, tongue tissue was positive by in situ hybridization at 4, 48, and 72 hours post-inoculation, yet there was never any microscopic evidence of degeneration or vesicle formation. From this preliminary study, it appears that, in the guinea pig, the virus is widely disseminated to foot pads and tongue, with epidermal lesions resulting only in selected areas.

Animals↗
PubMed1990

Proteoglycan biosynthesis by human corneas from patients with types 1 and 2 macular corneal dystrophy.

Corneal buttons were obtained from patients with types 1 and 2 macular corneal dystrophy (MCD) and from control patients with Fuchs' dystrophy or keratoconus. Buttons were incubated for 20 h in the presence of [3H]glucosamine or [2-3H]mannose. Radiolabeled proteoglycans and lactosaminoglycan-glycoproteins (L-GPs) were purified using chromatography on Q-Sepharose, Superose 6, and octyl-Sepharose. They were identified using chondroitinase ABC, keratanase or endo-beta-galactosidase digestion, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis or Superose 6 chromatography. This study confirms previous reports that type 1 MCD corneas synthesize a normal dermatan sulfate-proteoglycan (DS-PG) and an abnormal keratan sulfate-proteoglycan (KS-PG). The data indicate that typ 1 MCD corneas synthesize L-GP instead of KS-PG. This L-GP has a core protein of similar hydrophobicity (elution from octyl-Sepharose) and nearly similar mass (42 kDa) as the core protein of the KS-PG. It has identical glycoconjugates as those of the KS-PG except that they lack sulfate. Thus, type 1 MCD fails to synthesize keratan sulfate as a result of a defect in a sulfotransferase specific for sulfating lactosaminoglycans. Further, proteoglycans synthesized by a cornea from a patient with type 2 MCD were studied. This cornea synthesized a normal ratio of KS-PG to DS-PG although net synthesis of proteoglycans was approximately 30% below normal. The KS-PG appeared normal whereas the DS-PG had dermatan sulfate chains that were approximately 40% shorter than normal.

Cells, Cultured↗
PubMed1990

Endothelial rejection following penetrating keratoplasty using Healon or BSS.

In order to evaluate the effect of a commonly used sodium hyaluronate preparation (Healon, Pharmacia AB, Uppsala, Sweden) on the incidence of endothelial rejection, endothelial cell loss, intraocular pressure, and corneal thickness after penetrating keratoplasty, we conducted a randomized clinical trial. Patients were allocated to receive Healon (n = 41) or BSS (Alcon Laboratories, Inc., Fort Worth, TX, U.S.A.; n = 37) during surgery. At 1 year after surgery, the Kaplan-Meier estimate of the proportion remaining free of endothelial rejection was 78.1% (SE 6.5%) in the Healon group, and 70.6% (SE 7.9%) in the BSS group. Survival analysis showed no overall difference in endothelial rejection between groups. The percent loss in endothelial cell density showed substantial variability within each group, but for those followed 2 years after surgery, the amount of loss was significantly less in Healon-treated patients (17.3% versus 30.2%). Four Healon patients required medication for intraocular pressure rises in the early postoperative period, and the average intraocular pressure 1 day after surgery was greater in the Healon group (18.2 versus 13.7 mm Hg). Corneal thickness was slightly greater in patients receiving Healon, but no clinically important differences were noted.

Acetates↗
PubMed1990

A death resulting from trichlorotrifluoroethane poisoning.

Fatalities due to accidental exposure to chlorinated hydrocarbon in an industrial setting have been infrequently reported. The deaths in these cases have occurred within poorly ventilated, enclosed compartments or areas. A case is presented of a 16-year-old male who died as a result of exposure to trichlorotrifluoroethane while working in an open pit. Chromatographic results and tissue concentrations are presented.

Adolescent↗
PubMed1989

Implantation of posterior chamber intraocular lenses in the absence of lens capsule during penetrating keratoplasty.

We retrospectively studied the clinical records and the corneal endothelial cell counts of 133 consecutive eyes that received sutured posterior chamber intraocular lenses during penetrating keratoplasty in the absence of lens capsular support. Postoperative follow-up time ranged from three to 24 months, with 82 patients having at least one year of follow-up. At one year, 45.1% of these patients had 20/40 or better visual acuity, 30.5% had a visual acuity between 20/50 and 20/100, and 24.4% had a visual acuity of 20/200 or worse. At two years, 63.6% had a visual acuity of 20/40 or better, 18.2% had a visual acuity between 20/50 and 20/100, and 18.2% had a visual acuity of 20/200 or worse. Ninety-seven percent of the grafts remained clear at their latest follow-up examination. Cystoid macular edema (36.4%) and age-related macular degeneration (14.0%) accounted for poor visual acuity in most cases. Less common problems included graft rejection, retinal detachment, glaucoma, and endophthalmitis. At one year, the endothelial cell loss in the grafts averaged 19% with sutured posterior chamber intraocular lenses.

Aged↗
PubMed1989

Risk of endothelial rejection after bilateral penetrating keratoplasty.

Using univariate and multivariate survival analyses, the risk of endothelial rejection (ER) was compared between a group of patients undergoing penetrating keratoplasty (PK) in one eye only (unilateral PK) and a concurrent group who underwent PK in both eyes (bilateral PK). There was no significant difference in the time-related risk of ER between the bilateral and unilateral PK groups, after controlling for the increased risk of ER associated with younger age and preoperative stromal vascularity. Further analysis showed no increased ER risk to the first eye after the second eye's PK in the bilateral PK group. The documentation of simultaneous ER episodes in both eyes of two bilateral PK patients, however, may be evidence of an uncommon sharing of histocompatibility antigen(s) in the donor tissue used in these eyes.

Adolescent↗
PubMed1989

Corneal astigmatism after penetrating keratoplasty. The role of suture technique.

A randomized clinical trial was conducted to contrast two techniques of suturing in penetrating keratoplasty (PK) surgery: double running 10-0 and 11-0 sutures (DR), and a combination of 12 interrupted 10-0 sutures with a single running 11-0 suture (IR), followed by selective suture removal. The primary outcome evaluated in the 60 patients within each group was keratometric astigmatism. A decreasing trend in astigmatism over postoperative year 1 was observed only in the IR group (from 4.00 diopters [D] at 3 months to 2.50 D at 12 months). The difference in median astigmatism at 1 year (IR, 2.50 D; DR, 4.00 D) approached statistical significance (P = 0.06, Mann-Whitney U test). Both groups showed comparable steepening of almost 1 D during postoperative year 1. Assessment of the rate of visual rehabilitation was limited by a greater proportion of IR patients showing cystoid macular edema (CME) after surgery. These results, while favorable toward the IR/selective suture removal technique, must be substantiated by a final assessment after all sutures have been removed.

Aged↗
PubMed1989

Penetrating keratoplasty for corneal scarring due to herpes zoster ophthalmicus.

We retrospectively studied the postoperative results in nine patients with corneal scarring due to herpes zoster ophthalmicus who underwent penetrating keratoplasty. This was a highly selected group that satisfied all of the following criteria: (a) absence of active disease of the ocular surface and eyelids, (b) intraocular pressure under control, and (c) absence of active keratouveitis. Penetrating keratoplasty after herpes zoster ophthalmicus may do well in patients with long preoperative quiescent periods in whom these restrictive preoperative criteria are observed.

Aged↗
PubMed1989

Use of in situ hybridization for the detection of foot-and-mouth disease virus in cell culture.

Biotinylated complementary DNA (cDNA) and RNA probes were prepared from a specific and highly conserved section of the foot-and-mouth disease virus (FMDV) genome coding for the RNA-dependent RNA polymerase. Hybridization was conducted on FMDV-infected, bovine enterovirus (BEV)-infected, and noninfected swine kidney cell cultures. The detection system utilized the enzyme system streptavidin-alkaline phosphatase, the substrate phosphate, and the chromogen nitroblue tetrazolium. Intense cytoplasmic granular staining was present at 2 and 4 hr postinfection (hpi), with less staining observed at 24 hpi. The staining was specific for FMDV, as indicated by a lack of staining of noninfected cells and BEV-infected cells. With the RNA probe, positive cells were detected up to the highest viral dilution assayed, which was approximately 96 TCID50. The cDNA probe was slightly less sensitive, detecting positive cells at 10-fold lower dilutions. This technique could prove useful in the diagnosis of foot-and-mouth disease in animals or in the detection of FMDV in biologics submitted for importation.

Animals↗
PubMed1989

Changes in aqueous immunoglobulin and albumin levels following penetrating keratoplasty.

The feline model of induced rejection of corneal allografts was employed to define the changes in the concentrations of immunoglobulins and albumin in the anterior chamber prior to, and concomitant with the rejection of the transplanted cornea. Fourteen animals received unilateral exchange corneal allografts. Aqueous humor obtained by anterior chamber paracentesis at regular intervals prior to and following the performance of the penetrating keratoplasties was analyzed for IgG, IgM and albumin concentrations using the micro enzyme-linked immunosorbant assay (ELISA). Two patterns of anterior chamber protein modulation were observed. Eight of the animals demonstrated a biphasic pattern in which both immunoglobulin and albumin concentrations were elevated two- to five-fold above presurgical values 14 days postkeratoplasty, returning to preoperative values by day 42. Three to 5 weeks after corneal rejection was induced increases in protein concentrations were observed that correlated with the appearance of clinical signs of rejection. A second, monophasic pattern of anterior chamber protein modulation following keratoplasty was observed in four of the animals. It was distinguishable from the biphasic pattern in that levels did not return to baseline values after the initial rise following keratoplasty until the rejection process was completed. The monophasic response was found to be characteristic of more rapid and vigorous corneal rejection. Examination of albumin to immunoglobulin ratios suggested that all changes in protein levels following keratoplasty were a result of increased influx of serum proteins into the anterior chamber, rather than due to local immunoglobulin synthesis.

Animals↗
PubMed1989

Problems associated with penetrating keratoplasty for corneal edema in congenital glaucoma.

Corneal edema from congenital glaucoma is a rare indication for penetrating keratoplasty. We report the complications and problems associated with eight consecutive penetrating keratoplasties performed in adult eyes with a history of congenital glaucoma. Only 25% of the eyes achieved 20/40 or better vision after surgery. These generally poor results can be attributed to previous glaucomatous optic nerve damage, to complications related to previous surgery, and possibly to amblyopia. The most common surgical complication was postoperative elevation of intraocular pressure, which occurred in all the cases (8/8 eyes), and required permanent augmentation of glaucoma medications in seven eyes (88%), and glaucoma surgery in four eyes (50%). Two eyes (25%) developed corneal graft failure, one from immune rejection and the other from severe postoperative glaucoma necessitating cyclocryotherapy. In view of these complications and the multiple impediments to good postoperative vision, we advise that penetrating keratoplasty be reserved for patients with severe visual disability whose preoperative glaucoma is well controlled.

Adolescent↗