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Biomedical subjects

A Y Matoba

Publications and source records attributed to A Y Matoba.

At least 19 recordsLinked to original sources
PubMed1997

Conjunctival cilia entrapment: an unrecognized cause of ocular irritation.

Conjunctival entrapment of cilia is form of ocular irritation that to our knowledge has not yet been described. Scarring predisposes the conjunctiva to this phenomenon by creating blind recesses in which loose cilia can become entrapped. Once caught, the rigid cilia can act as a mechanical irritant or act as a nidus for microbial growth. We present herein three patients with entrapped cilia and discuss their pathophysiology and management. The symptoms in all three patients resolved with conjunctivoplasty and removal of the cilia.

Adult↗
PubMed1994

Infectious crystalline keratopathy due to Streptococcus pneumoniae. Possible association with serotype.

BACKGROUND: Infectious crystalline keratopathy is a distinctive clinical entity characterized by bacterial replication within the corena without inflammation. The authors report on a patient with infectious crystalline keratopathy due to Streptococcus pneumoniae serotype 11F. They used this isolate to study the contribution of the pneumococcal polysaccharide capsule to the pathogenesis of the infectious crystalline keratopathy. METHODS: Aliquots containing 10(6) colony-forming units of pneumococci serotype 11F, serogroup 9 or 15, were inoculated into New Zealand white rabbit corneas. The corneas were examined at 24, 48, and 72 hours. Representative corneas were excised at 24 hours and processed for histopathologic analysis. RESULTS: Pauci-inflammatory crystalline lesions developed in all corneas inoculated with the serotype 11F ocular isolate by 24 hours. Suppurative keratitis developed in control corneas inoculated with serogroup 9 or 15 pneumococci. The nonocular 11F isolates produced lesions with some features compatible with infectious crystalline keratopathy. CONCLUSION: Different pneumococcal serotypes vary in their ability to produce infectious crystalline keratopathy. Because serotype differences reflect differences in the antigenic polysaccharides of the bacterial capsule, this study suggests that properties of the pneumococcal capsule may influence the initial development of infectious crystalline keratopathy.

Aged↗
PubMed1994

The silent sinus syndrome. A cause of spontaneous enophthalmos.

PURPOSE: Spontaneous enophthalmos and hypoglobus, in the absence of other symptoms and unrelated to trauma or surgery, may be alarming to both physician and patient. The authors describe the clinicopathologic features of a benign syndrome ("silent sinus syndrome") with this constellation of features and discuss the possible pathophysiology. METHODS: A multicenter retrospective search for similar clinical cases was performed. All clinical records, computed tomographs, and pathology reports for each case were reviewed at one center. A literature search for similar cases also was conducted. RESULTS: Nineteen cases of a new syndrome are presented. This syndrome affects individuals at approximately the fourth decade of life (average age, 36 years; range, 29-46 years); is characterized by bone resorption and remodeling of the orbital floor due to otherwise asymptomatic maxillary sinus disease; is associated with ipsilateral maxillary sinus hypoplasia; and is not fully explained by any previously described, classic cystic lesion of the maxillary antrum. CONCLUSION: Enophthalmos and hypoglobus unassociated with prior trauma, surgery, or other symptoms may represent "silent sinus syndrome," which is ipsilateral maxillary sinus hypoplasia and orbital floor resorption.

Adult↗
PubMed1993

Infectious crystalline keratopathy. The role of bacterial exopolysaccharide.

OBJECTIVES: Infectious crystalline keratopathy is a unique pauci-inflammatory infection of the cornea most commonly due to viridans type streptococci. We investigated the hypothesis that production of exopolysaccharide by streptococci, a property that can be induced by growth conditions, may contribute to the pathogenesis of infectious crystalline keratopathy by suppressing the ocular immune response. METHODS: Streptococcus sanguis type II was grown under two conditions, conventionally in brain-heart infusion broth and in 5% sucrose-supplemented brain-heart infusion broth, to promote exopolysaccharide formation. Rabbit corneas were inoculated by passage of 9-0 silk sutures soaked in bacterial suspensions. RESULTS: Arborizing, sharply demarcated pauci-inflammatory lesions were noted in 71% of rabbit corneas inoculated with S sanguis type II grown in sucrose-supplemented media and in 25% of control corneas (P = .05). Suppurative lesions developed in the remaining corneas. Histologic evaluation of infectious crystalline keratopathy lesions revealed characteristic features. CONCLUSION: Increased exopolysaccharide formation by S sanguis type II is associated with production of infectious corneal lesions that resemble those of infectious crystalline keratopathy.

Animals↗
PubMed1993

Combination drug testing of Mycobacterium chelonae.

PURPOSE: Medical therapy of Mycobacterium chelonae keratitis is difficult because there are so few effective antimicrobial agents and single agent therapy frequently fails clinically. To identify more effective medical treatment regimens, the in vitro antimicrobial efficacy of amikacin, the most frequently used single agent, was investigated in combination with four antibiotics previously reported to have activity against M. chelonae: erythromycin, imipenem, ciprofloxacin, and vancomycin. METHODS: The drug combinations were tested by the checkerboard method against seven corneal isolates of M. chelonae. RESULTS: The combination of amikacin with erythromycin or vancomycin consistently led to synergistic or additive effect, however the minimum inhibitory concentrations for vancomycin were very high. The combination of amikacin with imipenem or ciprofloxacin led to results ranging from antagonism to additive effects. CONCLUSIONS: Of the antibiotics tested, erythromycin showed the most activity against M. chelonae in combination with amikacin. In vitro combination drug testing of M. chelonae by the checkerboard method should be further evaluated for clinical relevance in microbial keratitis.

Amikacin↗
PubMed1992

The solubility of antibiotic and corticosteroid combinations.

The use of collagen shields soaked in various combinations of medications has been advocated to enhance drug delivery to the cornea. Recently, severe corneal toxicity associated with aggregate formation in mixtures of gentamicin and methylprednisolone prompted our study of the effect of drug concentration, pH, and temperature on the solubility of several antibiotic and corticosteroid formulations commonly used to treat ocular disease. Selected combinations of cefazolin, vancomycin, tobramycin, gentamicin, methylprednisolone, and dexamethasone were evaluated. Mixtures of tobramycin and vancomycin produced no precipitates, but many spheroid aggregates were seen when methylprednisolone and gentamicin were combined. Although the effects of precipitate formation on drug bioavailability and toxicity have not been fully determined, until such information is available, the use of combinations of drugs that remain in solution during administration is recommended.

Anti-Bacterial Agents↗
PubMed1992

Visual results and complications of phacoemulsification with intraocular lens implantation performed by ophthalmology residents.

The authors retrospectively analyzed the visual outcome and incidence of complications of 181 consecutive cases of phacoemulsification performed by eight third-year ophthalmology residents. A posterior chamber intraocular lens was implanted in 179 of these eyes. Vitreous loss occurred in 5.5% of cases. The overall incidence of posterior capsule rupture was 9.9%; of the 18 posterior capsular ruptures, 72% were detected during cortical removal and 22% during nuclear emulsification. Postoperative follow-up for 177 eyes was at least 2 months, and 70% were followed for 6 months or longer. Final best corrected visual acuity of 20/40 or better was obtained in 92.6% of eyes. These results are comparable with previous reports of residents' experience in performing planned extracapsular cataract extraction. With appropriate training and faculty supervision, residents learning to perform phacoemulsification and intraocular lens implantation can achieve acceptable results.

Cataract Extraction↗
PubMed1991

The effects of fibronectin on the adherence of bacteria to corneal epithelium.

The aim of our experiments was to determine whether treatment with topical fibronectin led to increased adherence of Staphylococcus aureus or Pseudomonas aeruginosa to rabbit corneas with epithelial defects. No significant effect of fibronectin was demonstrated. For all strains of S. aureus tested, the number of recoverable organisms was decreased at 24 h compared to 1 h. None of the rabbits developed infectious keratitis.

Administration, Topical↗
PubMed1989

The effects of freezing and antibiotics on the viability of Acanthamoeba cysts.

The effects of cryotherapy and antibiotics (paromomycin, neomycin, or propamidine isethionate) on the viability of Acanthamoeba polyphaga and Acanthamoeba castellani cysts were studied in vitro. Either cryotherapy or exposure to antibiotic led to a decrease in the number of viable A castellani detected; A polyphaga showed variable response to the antibiotics tested. The combination of cryotherapy and antibiotic therapy was more cysticidal than either modality alone and eliminated detectable viable organisms in five of six experiments. Of the antibiotic solutions tested, paromomycin (15 mg/mL) was the most effective.

Acanthamoeba↗
PubMed1989

The use of fluorescein-conjugated lectins for visualizing atypical mycobacteria.

We investigated the feasibility of using fluorescein-conjugated lectins for visualizing and differentiating two species of atypical mycobacteria. Pure cultures of Mycobacterium fortuitum and Mycobacterium chelonei were established, as was an experimental model of infectious keratitis involving these two organisms. Samples from the pure cultures and corneal scrapings were placed on glass slides, fixed, and incubated with one of a panel of 22 fluorescein-conjugated lectins. The slides were examined using an epifluorescence microscope. Fluorescein-conjugated concanavalin A brightly stained both species of atypical mycobacteria, in both the pure culture and experimental keratitis samples. Several additional fluorescein-conjugated lectins (wheat germ agglutinin, succinylated wheat germ agglutinin, Phaseolus vulgaris erythroagglutinin, and Psophocarpus tetragonolobus agglutinin) brightly stained M chelonei, but only moderately stained M fortuitum. These staining patterns are consistent with the known carbohydrate compositions of the cell walls of atypical mycobacteria and suggest that fluorescein-conjugated lectins may be useful for the visualization of these organisms in corneal infections.

Abscess↗
PubMed1989

Bacterial keratitis after radial keratotomy.

The authors identified nine patients with culture-proven keratitis after radial keratotomy (RK). Three patients became infected in the immediate post-operative period, and six patients had delayed-onset keratitis. Gram-negative rods were the predominant pathogens in late-onset keratitis (4 of 6 infections). Gram-positive cocci were implicated in all three postoperative infections. The inferior corneal quadrants were involved in seven of nine patients. Two episodes of late-onset keratitis were associated with contact lens wear. Five of these patients had transverse incisions or greater than eight radial cuts. All six patients regained visual acuity of 20/40 or better. Two additional cases of early-onset and six cases of late-onset keratitis with many features similar to these cases have been reported previously.

Adult↗
PubMed1986

The autoimmune nature of aqueous tear deficiency.

Twenty-two patients with aqueous tear deficiency (ATD) were examined for the presence of the following autoantibodies: immunofluorescent antinuclear antibody (ANA) and Sjögren's syndrome antibodies A and B (SS-A and SS-B). These autoantibodies were found in 17 (82%) patients but not in control subjects, and they correlated with the severity of symptoms and ocular surface changes. Bacterial keratitis, often recurrent and bilateral, and progressive sterile corneal stromal melting developed in six autoantibody-positive ATD patients. Eight antibody-positive patients had labial salivary or lacrimal gland biopsies, and all showed similar histologic features with marked destruction of the glandular architecture by lymphocytic infiltration. Immunoglobulin and complement were not detected in the glandular tissue. Circumstantial evidence suggests that an abnormal immunologic reaction, possibly related to Epstein-Barr viral (EBV) infection, is the cause of the glandular destruction and tear deficiency.

Autoantibodies↗
PubMed1986

Epstein-Barr viral stromal keratitis.

We have identified seven patients with clinical and serological features suggestive of Epstein-Barr viral (EBV) stromal keratitis. Four had discrete, sharply demarcated, multifocal, pleomorphic or ring-shaped granular anterior stromal opacities with normal intervening stroma, seemingly distinct from adenoviral or herpes simplex stromal keratitis. Two had soft, blotchy, pleomorphic, multifocal infiltrates, predominantly involving the peripheral cornea at all depths, and with minimal neovascularization, resembling syphilitic stromal keratitis. One patient had features or both forms of keratitis. OUr experience suggests that EBV may be more commonly associated with stromal keratitis than recognized previously.

Adolescent↗
PubMed1986

T cell subsets in the immune rejection of murine heterotopic corneal allografts.

Using a previously described murine heterotopic corneal allograft model, we examined the roles of delayed-type hypersensitivity (DTH) and cytotoxic T lymphocytes (CTL) in corneal allograft rejection. We have previously shown that normal C57BL/6 mice consistently reject heterotopic corneal allografts within 14 days of grafting. These hosts develop antigen-specific CTL responses but no evidence of DTH reactivity. The absence of DTH suggested that this T cell subset was unnecessary for corneal allograft rejection. The present studies using T cell-deficient mice selectively reconstituted with specific T cell subsets confirmed this suspicion. T cell-deficient (i.e., adult thymectomized, lethally irradiated, bone marrow-reconstituted = ATXBM) C57BL/6 mice were selectively reconstituted with the following categories of syngeneic lymph node cells (LNC): BALB/c skin-immune LNC treated with anti-Lyt 1 antibody + complement; BALB/c skin- or cornea-immune LNC treated with anti-Lyt 2 antibody + complement; or BALB/c cornea- or skin-immune LNC not treated with antibody. ATXBM mice reconstituted with syngeneic Lyt 1-depleted, BALB/c skin-immunized LNC failed to develop DTH, yet rapidly rejected BALB/c corneal allografts. Similarly, ATXBM mice reconstituted with Lyt 1-depleted cornea-immune LNC did not demonstrate DTH responses but were able to reject 100% of the corneal allografts in an accelerated fashion. By contrast, corneal allograft rejection was significantly delayed in ATXBM mice reconstituted with cornea-immune LNC partially depleted of Lyt 2+ T cells. Collectively, the results indicate that: heterotopic corneal allografts can be rejected in the absence of DTH; heterotopic corneal allografts fail to induce allospecific DTH; and partial depletion of Lyt 2+ CTL leads to a prolongation of heterotopic corneal allograft survival. Thus, the primary T cell-dependent immune effector elements responsible for heterotopic corneal allograft rejection appears to reside in the cytolytic T lymphocyte population.

Animals↗
PubMed1985

Mucus fishing syndrome.

Twenty-five patients are described with a variety of external ocular diseases including keratoconjunctivitis sicca, blepharitis, and allergic conjunctivitis, who presented with persistence of symptoms of irritation, foreign body sensation, and apparent excessive mucus production, with mild conjunctival inflammation despite appropriate treatment of the underlying disease. All patients were found to have evidence of trauma to the conjunctival epithelium due to mechanical removal of the excess mucus from the surface of the globe or inferior cul-de-sac. The surface irritation created by the mechanical damage led to a further increase in mucus production, creating a cycle that we have termed mucus fishing syndrome. Cessation of this behavior coupled with ongoing therapy of the underlying disease led to resolution of signs and symptoms in all patients.

Adult↗