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Biomedical subjects

R W Yee

Publications and source records attributed to R W Yee.

At least 37 records · Page 2Linked to original sources
PubMed1992

Effects of flurbiprofen and suprofen on the miotic activity of 1% acetylcholine and 0.01% carbachol.

The nonsteroidal antiinflammatory agents (NSAIAs) flurbiprofen and suprofen applied topically to reduce miosis may counteract the desired effects of miotics used during ocular surgery. In a pigmented rabbit model, 1% acetylcholine was shown to cause a greater, significant initial (for the first 30 minutes) constriction (P less than .05) than 0.01% carbachol in eyes pretreated with flurbiprofen and suprofen. From 2 to 8 hours, NSAIA pretreatment had a greater miotic effect with carbachol than with acetylcholine. There were no significant differences between flurbiprofen and suprofen on the miotic effect of carbachol or acetylcholine.

Acetylcholine↗
PubMed1991

Resolution of microsporidial epithelial keratopathy in a patient with AIDS.

A patient with a positive human immunodeficiency virus (HIV) titer and cryptococcal meningitis suffered bilateral epithelial keratopathy caused by Encephalitozoon, which did not respond to sulfas, erythromycin, bacitracin, tobramycin, neomycin, polymyxin B, or fluconazole. Eventual administration of itraconazole for the meningitis apparently produced resolution of the long-lasting (2-month) ocular infection. This new oral triazole antifungal may be valuable against the increasingly prevalent microsporidial infections in patients with acquired immune deficiency syndrome. Debulking of the infection by corneal scraping may have contributed to the authors' success.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Isolation and characterization of a new human microsporidian, Encephalitozoon hellem (n. sp.), from three AIDS patients with keratoconjunctivitis.

A new human microsporidian was isolated from cultures of Madin-Darby canine kidney cells incubated with conjunctival scrapings or corneal tissues from three AIDS patients with keratoconjunctivitis. The three isolates were morphologically similar to Encephalitozoon cuniculi. The spores averaged 1 x 1.5-2.0 microns, had six to eight polar filament coils, displayed monokaryotic nuclei, and possessed relatively thick endospores with irregularly shaped exospores. Organisms developed within a parasitophorous vacuole. By SDS-PAGE analysis, the three isolates appeared to be identical but were different from E. cuniculi. Identical banding patterns on Western blots of the three isolates were expressed by each patient's serum. By Western immunoblotting, murine antisera to E. cuniculi reacted to several antigens of the new AIDS-related microsporidian, whereas murine antisera bound weakly to Nosema corneum. The name Encephalitozoon hellem (n. sp.) is proposed to identify this new human microsporidian.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Multiple endocrine neoplasia type III.

The multiple endocrine neoplasia (MEN) syndromes are autosomally dominant inherited disorders in which hyperplastic or neoplastic changes occur in a wide variety of tissues. The specific syndromes are classified according to the endocrine glands affected. MEN type I consists of an aggregation of tumors of parathyroid, pancreatic, and pituitary glands. The association of medullary carcinoma of the thyroid (MCT) and pheochromocytoma is called MEN type II or type IIA, and if combined with mucosal neuromas, intestinal ganglioneuromatosis, and prominent corneal nerves, is named MEN type III or type IIB. Individuals afflicted with MEN type III are characterized by a marfanoid habitus, mucosal neuromas involving oral and ocular tissues, and a number of ophthalmologic findings including prominent corneal nerves, thickened eyelids, and subconjunctival neuromas. These features are easily recognized during the ocular exam, allowing the ophthalmologist to make an early diagnosis of this syndrome prior to the onset of life-threatening manifestations like medullary thyroid carcinoma and pheochromocytoma.

Adult↗
PubMed1991

Apparent cytomegalovirus epithelial keratitis in a cardiac transplant recipient.

A 44-year-old immunosuppressed man developed initial symptoms of intermittent irritation of the left eye three months after cardiac transplantation. Symptoms increased, with decreased vision, photophobia, and lacrimation. Slit lamp examination showed slightly raised, swollen, grayish epithelium in a broad multibranching dendritic pattern associated with fine and medium punctate epithelial erosions that stained slightly with fluorescein. Histopathologic study of the corneal epithelial scraping demonstrated swollen epithelial cells with intranuclear and intracytoplasmic viral inclusions. Viral cultures manifested a cytopathic pattern characteristic of cytomegalovirus 14 days after inoculation on human embryonic lung cells (MRC-5). Pretransplantation cytomegalovirus IgM and IgG serologic titers were negative (less than 1:16 for IgG, no IgM noted) until the onset of symptoms. Subsequently, IgM titers rose against cytomegalovirus consistent with concurrent infection.

Adult↗
PubMed1991

Microbial keratitis associated with plano tinted contact lenses.

The use of plano contact lenses for cosmetic purposes is a recent phenomenon. We report five cases of severe microbial keratitis associated with the use of these lenses. This subpopulation of patients who possess no refractive error are at risk of developing severe complications from contact lens wear. We have identified several issues which should be addressed by eye care professionals and regulatory agencies.

Acanthamoeba Keratitis↗
PubMed1990

Diurnal rhythms of immunoreactive melatonin in the aqueous humor and serum of male pigmented rabbits.

Using specific radioimmunoassays, melatonin was quantified in the aqueous humor and serum of male pigmented rabbits adapted to 12L:12D with lights on at 06.00 h. Melatonin concentrations in the aqueous humor at 08.00 and 16.00 h were similar (mean: 5.23 pg/ml) and significantly lower than those at 22.00 and 01.00 h (mean: 22.06 pg/ml). A parallel rhythm was also demonstrated in the serum with higher melatonin concentrations (daytime mean: 75.26 pg/ml; nighttime mean: 168.94 pg/ml). We propose that the aqueous melatonin rhythm is associated with the rhythmic change in aqueous flow.

Animals↗
PubMed1990

Multiple endocrine neoplasia type IIB identified by magnetic resonance imaging.

Ectopic, epinephrine-secreting pheochromocytomas are rare and difficult to diagnose. In our case, MRI was able to show the lesion, which could not be clearly identified by CT. The histologic specificity provided by T2-weighted images confirmed the biochemical diagnosis of pheochromocytoma. MRI should be considered as an alternative to CT in the diagnosis of familial pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMed1990

Ascorbate-enhanced copper toxicity on bovine corneal endothelial cells in vitro.

The present results indicate that 30 micrograms/ml copper was toxic to bovine corneal endothelial cells (BCEC) cultured in a serum-free medium (SFM) when the duration of treatment was 72 hours or more. Copper at 10 micrograms/ml, if mixed with 50 micrograms/ml ascorbate 2 to 3 hours before treatment, caused a transient decrease in the number of nuclei/mm2 at 72 hour, whereas 10 micrograms/ml copper alone was apparently non-toxic. When 10 micrograms/ml copper was added to 50 micrograms/ml ascorbate at the time of treatment, the toxicity was increased. All the treated cells failed to survive beyond 24 hours, and copper at a lower concentration of 1 microgram/ml could inhibit the proliferation of BCEC. We propose that copper toxicity on BCEC is augmented by ascorbate possibly through the increased replenishment of Cu+ and the subsequent enhanced production of free radicals by copper auto-oxidation.

Analysis of Variance↗
PubMed1989

Diagnostic impression cytology for external eye disease.

The authors describe their experience with the use of impression cytology (IC) as a diagnostic aid in the evaluation of external eye disorders. IC is shown to be useful for diagnosis of epithelial cell storage disorders, infectious diseases, and allergic disorders.

Chlamydia Infections↗
PubMed1988

Elevated tear IgG and conjunctival plasma cell infiltrate in a graft versus host disease patient.

Two patients developed graft versus host disease (GvHD) following allogeneic bone marrow transplantation for leukemia. One patient developed acute GvHD 12 days after transplantation, and the second developed chronic GvHD 100 days after transplantation. Tear analysis and conjunctival impression cytology were performed. The results were compared to a normal control and to another patient who was 18 months status post bone marrow transplantation with successfully treated GvHD. Tear sampling on the patient with chronic GvHD revealed greatly elevated IgG levels with an inverse IgG to IgA ratio, as compared with normals. In addition, two of three leukemia patients demonstrated decreased mucin levels in tears. Conjunctival impression cytology from the patient with chronic GvHD revealed an abundance of plasma cells.

Adult↗
PubMed1987

Specular microscopy of vertebrate corneal endothelium: a comparative study.

Central corneal endothelia in a variety of lower- and higher vertebrate animals were photographed with a widefield specular microscope and analysed with either fixed-frame or computer-assisted morphometric analysis. The endothelium of the dogfish shark, an elasmobranch, contained 2300 cells mm-2 and demonstrated a very delicate irregular 'reversal pattern'. The goldfish, a teleost, had 432 cells mm-2 and displayed a jigsaw-puzzle-like pattern. The bullfrog, an amphibian, and the gecko, a reptile, had 550- and 481 cells mm-2, respectively, and a relatively uniform polygonal endothelial pattern similar to that observed in mammals. The goose, a bird, had a cell density of 2410 cells mm-2 with a uniform hexagonal pattern (79%) which was similar to mammalian (rat, 58-76%; rabbit, 71%; dog, 78%; human, 61-75%) hexagonal patterns. The findings on the endothelial appearance in these vertebrate animals suggest that a correlation exists between endothelial morphology, vertebrate phylogeny and their respective functional and structural capacity.

Animals↗
PubMed1986

Specular microscopic evaluation of donor corneal endothelium.

We performed wide-field specular microscopy and pachymetry on 92 donor corneas to evaluate the changes occurring in the endothelium during moist chamber storage of up to 48 hours. Endothelial changes were quantitated with computer-assisted morphometry. The donor corneas were divided into two groups: younger (mean age, 34 years) and older (mean age, 72 years). No significant differences in endothelial cell density, coefficient of variation in cell area (polymegethism), percentage of hexagonal cells (pleomorphism), or central corneal thickness were noted between younger and older donors when storage intervals were similar. Within each group, while endothelial cell density remained constant, a marked increase in polymegethism and pleomorphism developed when storage was prolonged beyond 12 hours. Corneal thickness also increased, but there was no correlation between thickness and the extent of the endothelial changes. These results suggest that specular microscopy is a more reliable method of screening donor tissue than donor age or corneal thickness.

Adolescent↗
PubMed1986

Response of the corneal endothelium to cataract surgery.

Regional changes in endothelial cell density, morphology, and corneal thickness were serially examined with a specular microscope after intracapsular cataract extraction (four eyes), extracapsular cataract extraction (five eyes), and extracapsular cataract extraction with posterior chamber lens implantation (13 eyes). Regardless of the type of cataract surgery, cell loss and morphologic changes (decreased percentage of hexagonal cells, increased cellular elongation, and increased coefficient of variation) were greatest and occurred within one week in the superior cornea. Similar changes occurred after one month centrally but were minimal inferiorly. Endothelial cell density stabilized, and the morphologic changes resolved within three months in all regions of the cornea. Corneal swelling resolved within one month. Differences between the procedures were noted only in the superior portion of endothelium, where cell loss and morphologic changes were greatest following intracapsular cataract extraction. Also, endothelial wound healing was complete and stable three months after cataract surgery, with or without posterior chamber lens implantation.

Adult↗
PubMed1986

Comparison of intraocular acetylcholine and carbachol.

Commercially available 1% acetylcholine chloride and 0.01% carbachol chloride, which are commonly used as miotics in intraocular surgery, have recently been reformulated. Comparative studies of these agents show similar miotic activity. However, in vitro perfusion of human corneas demonstrated that 1% acetylcholine chloride causes marked changes in endothelial function and ultrastructure as compared to carbachol or BSS Plus. This study showed that 0.01% carbachol chloride was less toxic to the corneal endothelium than 1% acetylcholine chloride and suggests that 1% acetylcholine should not be used in corneas with compromised endothelium as in primary corneal endotheliopathies.

Acetylcholine↗