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Biomedical subjects

I Chowers

Publications and source records attributed to I Chowers.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of microcirculation patterns and MIB-1 immunoreactivity in iris and posterior uveal melanoma.

PURPOSE: To compare melanomas confined to the iris and those involving either the ciliary body or choroid for the histologic features of microcirculation patterns and tumor cell proliferation indices. DESIGN: Retrospective comparative human tissue study. PARTICIPANTS: Ninety-eight uveal melanomas were studied, including 18 tumors confined to the iris, 30 tumors involving the ciliary body, and 50 tumors confined to the choroid. METHODS: Formalin-fixed, paraffin-embedded sections from each tumor were stained with hematoxylin-eosin and with periodic acid-Schiff. Adjacent histologic sections were stained with the MIB-1 antibody that reacts with the Ki-67 antigen. MAIN OUTCOME MEASURES: Microcirculation patterns were assessed in the periodic acid-Schiff-stained sections. Proliferative activity was assessed in the MIB-1-stained sections. The mean MIB-1 positive cell count per high-power field (HPF) was calculated in 10 HPF (x 40) in the area of maximal immunoreactivity. Two observers evaluated each MIB-1-stained section, and the interobserver reproducibility was assessed. RESULTS: Histologic microcirculation patterns associated with death from metastatic disease in ciliary body and choroidal melanomas (parallel vessels with cross-linking and networks of back-to-back loops) were not found in any of the iris melanomas. By contrast, 34% and 63% of the choroidal and ciliary body melanomas, respectively, showed at least one of these patterns. The mean positive cell count per HPF +/- standard error was 19.9 +/- 3.5, 27 +/- 5.3, and 1.9 +/- 0.4 in choroidal, ciliary body, and iris melanoma, respectively (P: = 0.003, Kruskal-Wallis test). CONCLUSIONS: Melanoma confined to the iris is characterized by a low rate of proliferation and the histologic absence of microcirculation patterns associated with metastatic posterior uveal melanoma. Both features are consistent with the relatively benign nature of iris lesions compared with melanomas involving the ciliary body or choroid.

Adult↗
PubMed2001

Proliferative activity and p53 expression in primary and recurrent pterygia.

PURPOSE: To assess p53 expression and proliferative activity in primary and recurrent pterygia from the same eyes. DESIGN: Retrospective comparative human tissue study. PARTICIPANTS: Tissue from excised primary pterygia that did not recur (group A, n = 10) was compared with tissue from primary pterygia that recurred (group B, n = 10) and to the recurrent pterygia tissue that was excised from subjects in group B (group C, n = 10). Ten normal conjunctivas served as controls (group D). METHODS: Sections from each pterygium were immunostained with the MIB-1 and bp53. 12 monoclonal antibodies that react with Ki-67 and p53 antigens, respectively. MAIN OUTCOME MEASURES: Proliferative activity was calculated as the mean of the MIB-1 positive cell count per eyepiece grid in high magnification (x40) (positive cell count/grid). Percentage of positive cells of all cells in the grid area was evaluated in the p53-stained sections. RESULTS: Proliferative activity was found in the epithelium overlying the pterygia and normal conjunctiva. The mean MIB-1 positive cell count/grid +/- standard error was 2.84 +/- 1.07, 1.74 +/- 0.82, 3.83 +/- 1.35, and 0.86 +/- 0.33 in groups A, B, C, and D, respectively (P = 0.17, Kruskal-Wallis). P53 staining was found in 50% of pterygia in groups A, B, and C; none of the normal conjunctival tissues showed p53 immunoreactivity. Four of five p53-positive tissues in group B were p53-negative in group C. In the p53-positive pterygia, less than 10% of cells were p53 positive. However, p53-positive pterygia had higher mean MIB-1 positive cell count/grid +/- standard error as compared with the p53-negative lesions, 4.56 +/- 0.94 vs 1.39 +/- 0.59 (P = 0.021, Mann-Whitney). CONCLUSIONS: p53 immunoreactivity and high proliferative activity in the epithelium overlying the pterygium are not associated with recurrence of pterygium.

Antibodies, Monoclonal↗
PubMed2001

Gene transfer by viral vectors into blood vessels in a rat model of retinopathy of prematurity.

AIMS: To test the feasibility of gene transfer into hyaloid blood vessels and into preretinal neovascularisation in a rat model of retinopathy of prematurity (ROP), using different viral vectors. METHODS: Newborn rats were exposed to alternating hypoxic and hyperoxic conditions in order to induce ocular neovascularisation (ROP rats). Adenovirus, herpes simplex, vaccinia, and retroviral (MuLV based) vectors, all carrying the beta galactosidase (beta-gal) gene, were injected intravitreally on postnatal day 18 (P18). Two sets of controls were also examined: P18 ROP rats injected with saline and P18 rats that were raised in room air before the viral vectors or saline were injected. Two days after injection, the rats were killed, eyes enucleated, and beta-gal expression was examined by X-gal staining in whole mounts and in histological sections. RESULTS: Intravitreal injection of the adenovirus and vaccinia vectors yielded marked beta-gal expression in hyaloid blood vessels in the rat ROP model. Retinal expression of beta-gal with these vectors was limited almost exclusively to the vicinity of the injection site. Injection of herpes simplex yielded a punctuate pattern of beta-gal expression in the retina but not in blood vessels. No significant beta-gal expression occurred in rat eyes injected with the retroviral vector. CONCLUSIONS: Adenovirus is an efficient vector for gene transfer into blood vessels in an animal model of ROP. This may be a first step towards utilising gene transfer as a tool for modulating ocular neovascularisation for experimental and therapeutic purposes.

Animals↗
PubMed2000

Retinitis pigmentosa associated with Fuchs' heterochromic uveitis.

OBJECTIVE: To investigate whether the combination of Fuchs' heterochromic uveitis (FHU) and retinitis pigmentosa (RP) in the same patient is coincidental or represents a true association. METHODS: We have examined the frequency of FHU in 338 patients with RP and in 1984 patients who were seen in our primary care ophthalmic clinic because of reasons other than RP. RESULTS: Of 338 patients with RP, 4 (1.2%) had the typical findings of FHU. Three of them had Usher syndrome type II, and 1 had RP simplex. By contrast, only 1 patient in the control group had FHU (5%), and the difference in the frequency of FHU between the 2 groups was significant (P=.002, Fisher exact test). CONCLUSIONS: Fuchs' heterochromic uveitis is associated with RP. Since autoimmune phenomena have been previously described in patients with RP, it is conceivable that RP predisposes to the development of FHU. Arch Ophthalmol. 2000;118:800-802

Adolescent↗
PubMed1999

Laser pointer maculopathy.

PURPOSE: To report a case of macular damage from a laser pointer. METHOD: Case report. A 19-year-old woman had an acute reduction of visual acuity in the right eye after deliberately staring into a commercial class 2 laser pointer for approximately 10 seconds. RESULTS: The patient's best-corrected visual acuity was RE: 20/40, and she had two small pericentral scotomata, as well as a hypopigmented ring-shaped lesion in the fovea. Within 8 weeks, her visual acuity improved to 20/20 and visual field returned to normal, but a subjective relative decrease in brightness of objects viewed by the right eye was apparent. Retinal pigment epithelial abnormality persisted. CONCLUSIONS: Commercial laser pointers, commonly used for teaching and entertainment purposes, may cause notable macular damage if abused. Morphologically, this may manifest as foveal retinal pigment epithelial disturbance.

Acute Disease↗
PubMed1999

Neurotrophic corneal endothelial failure complicating acute Horner syndrome.

PURPOSE: The authors report the clinical findings of a unique case of rapid corneal endothelial decompensation in association with acute Horner syndrome. STUDY DESIGN: Case report and literature review. METHODS: The authors followed a 38-year-old woman who developed Horner syndrome after right jugular vein catheterization during cardiac valvular surgery. Shortly after the operation, Horner syndrome accompanied by conjunctival hyperemia and stromal corneal edema developed in the right eye. Over the course of 4 months, the eye became painful, the corneal endothelial cell count dropped precipitously, and the stromal edema worsened, causing a difference of 100 microm in central corneal thickness compared to the unaffected eye. Deep stromal vascularization started at the limbus, resembling interstitial keratitis. RESULTS: A 3-week course of topical steroid treatment resulted in a dramatic improvement in the stromal corneal edema and regression of the deep stromal vascularization. Ocular and right hemicranial pain subsided shortly thereafter. CONCLUSION: The authors hypothesize that corneal endothelial failure in this unique case may have resulted from traumatic sympathectomy. According to experimental evidence in the reviewed ophthalmologic literature, sympathetic innervation may have a neurotrophic role in the cornea. Corneal pathology similar to the authors' case has been described in hemifacial atrophy (Parry-Robson syndrome), a disorder that is assumed to result from sympathetic denervation and that can be produced in animals by cervical sympathectomy. The authors therefore hypothesize that sympathetic denervation of the cornea may rarely cause endothelial decompensation and corneal edema. To the authors' knowledge, this is the first reported case of corneal endothelial failure in Horner syndrome.

Acute Disease↗
PubMed1999

Cone and rod dysfunction in the NARP syndrome.

AIMS: Description of the ophthalmic manifestations of the NARP (neuropathy, ataxia, retinitis pigmentosa) syndrome that is associated with a point mutation in position 8993 of the mitochondrial DNA (mtDNA). METHODS: A mother and her two children, all carrying the 8993 mtDNA mutation, were examined. Two had manifestations of the NARP syndrome. A complete ocular and systemic examination was performed on all three patients. RESULTS: The clinical examination, electroretinogram, and visual fields revealed a typical cone-rod dystrophy in the son, and a typical cone dystrophy in the daughter. The mother had no ocular manifestations of the disease. CONCLUSIONS: NARP is a recently described, maternally inherited mitochondrial syndrome in which a retinal dystrophy, among other abnormalities, is related to a mutation of the mtDNA at nucleotide 8993. This study demonstrates the great variability of the ocular manifestations in the NARP syndrome. It also indicates that the retinal dystrophy in at least some NARP patients affects primarily the cones.

Adolescent↗
PubMed1999

Immunostaining of the estrogen receptor in conjunctival primary acquired melanosis.

Conjunctival primary acquired melanosis (PAM) is a frequent precursor of conjunctival melanoma. Since there is indirect evidence that the conjunctiva is an estrogen-responsive tissue, and since it was suspected that estrogen has a role in the etiology of melanoma, we decided to evaluate whether PAM may be responsive to estrogen. Formalin-fixed, paraffin-embedded sections from 13 cases of PAM and 2 cases of conjunctival melanoma were immunostained with an estrogen-receptor (ER)-specific antibody. All lesions and the normal conjunctival tissue adjacent to the lesions were found to be ER negative. It is concluded that PAM and normal conjunctiva are not sensitive directly to estrogen. When considering previously reported data, it is conceivable that the normal conjunctiva, but not PAM, is indirectly affected by estrogen.

Adolescent↗
PubMed1999

Mitomycin-C in combined or two-stage procedure trabeculectomy followed by penetrating keratoplasty.

PURPOSE: To evaluate the efficacy and safety of application of mitomycin-C (MMC) in combined and separate trabeculectomy and penetrating keratoplasty for the treatment of coexisting corneal disease and glaucoma. METHODS: A retrospective evaluation of 11 eyes of 10 patients was conducted. A combined trabeculectomy with MMC and penetrating keratoplasty procedure was performed in eight eyes (group 1), and keratoplasty was performed after a previous trabeculectomy with MMC in three eyes (group 2). RESULTS: In group 1, seven of the eight eyes had controlled intraocular pressure (IOP) and clear corneal graft at the end of the follow-up period (range, 5-60 months; mean duration, 16.7 months). In group 2, all three eyes had controlled IOP at the end of the follow-up period (range, 4-30 months; mean duration, 14 months); two of these patients had clear corneal grafts, and graft failure occurred in the remaining patient. Complications included transient flat anterior chamber and corneal epithelial defects, each of which occurred in a single eye in group 1, and progressive cataract, which occurred in a single eye in group 2. CONCLUSION: Mitomycin-C was found to be safe and efficient in the present series, controlling IOP in 10 of 11 eyes (91%) with coexisting corneal disease and glaucoma. The transplanted corneas remained clear in 9 of 11 eyes (82%). Complications related to MMC included a reversible epithelial defect that occurred in one eye.

Adolescent↗
PubMed1998

Deep stromal inflammation--a possible new ocular manifestation of Crohn's disease.

Crohn's disease, an inflammatory bowel disease, is infrequently associated with epithelial and subepithelial corneal inflammation. However, deep stromal inflammation has not been described previously in association with Crohn's disease. We report on a 52-year-old male who suffered from anterior uveitis and deep stromal inflammation. Complete ocular and systemic workup revealed an active asymptomatic Crohn's colitis; no other possible cause for the ocular inflammation was found. We conclude that deep stromal inflammation, in addition to the previously reported corneal epithelial inflammation, may be associated with Crohn's disease.

Colitis↗
PubMed1998

MIB-1 and PC-10 immunostaining for the assessment of proliferative activity in primary acquired melanosis without and with atypia.

AIMS: To compare the proliferative activity of intraepithelial melanocytes in primary acquired melanosis (PAM) without atypia and PAM with atypia by immunohistochemical staining for the Ki-67 antigen and the proliferating cell nuclear antigen (PCNA). METHODS: Formalin fixed, paraffin embedded sections from 35 archival specimens of PAM without atypia (n = 19) and with atypia (n = 16) were studied by immunostaining with MIB-1 and PC-10 monoclonal antibodies that react with the Ki-67 antigen and PCNA respectively. The results were calculated as the mean number of positive cells per eyepiece grid. All specimens were evaluated by two masked observers, and the interobserver reproducibility was assessed. RESULTS: The means of the positive cell count in PAM with atypia were significantly higher compared with PAM without atypia for both observers, in both the PC-10 and the MIB-1 stained sections. In a linear least square model that estimated the interobserver and between group variation, the difference of MIB-1 and PC-10 positive cell count between PAM without and with atypia remained highly significant. The difference between the observers was not significant. CONCLUSIONS: Immunostaining with MIB-1 and PC-10 demonstrated that PAM with atypia has higher proliferative activity than PAM without atypia. This method was found to be reproducible between different observers.

Antigens, Nuclear↗
PubMed1996

Vinblastine toxicity to the ocular surface.

Local ocular exposure to antineoplastic drugs occurs either during regular use of some of these drugs in ophthalmology or accidentally during the general use of these drugs. Many ocular side effects have been described after such intentional or accidental exposures. We describe a case of accidental ocular trauma by vinblastine. As in one of the only two previously published cases of ocular trauma by vinblastine, our patient showed acute keratopathy with a drop in visual acuity followed by the development of dry eyes and a subepithelial corneal scar. In addition, in an attempt to further evaluate the clinical course and the benefits of steroid treatment, nine rabbits were studied after ocular instillation of vinblastine. After the trauma, local steroid treatment was given in one eye of each rabbit; the second eye served as a control. The animal studies showed acute conjunctivitis and keratopathy with increasing severity in the first days and improvement thereafter. That course was similar to the one manifested in our patient. Local steroid treatment in the rabbit eye had no effect as compared with the control group. A possible mechanism for the induction of dry eyes is discussed.

Accidents, Occupational↗