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PubMed1995

Iron uptake by cultured lens epithelial cells.

BACKGROUND: Transferrin and Fe concentrations increase in the intraocular fluids in pathological conditions and the lens accumulates Fe during ocular inflammation. Tissues take up Fe from transferrin by two mechanisms, receptor-medicated endocytosis of diferric transferrin and a process occurring at the cell membrane which may be mediated by an oxido-reductase. However, Fe metabolism, transport and storage have not been previously investigated in the lens. This study was designed to characterize the uptake of Fe from transferrin by lens epithelial cells in culture. METHODS: Primary, secondary and tertiary cultures of canine lens epithelial cells and cultures obtained from cataractous lenses were studied. Uptake of 59Fe from transferrin by these cultured cells was measured. Transferrin receptor populations were determined in receptor-binding assays. RESULTS: There was a distinct relationship between the amount of Fe-transferrin added and the amount of Fe taken up, which was linear for the primary cultures but significantly reduced for the secondary, tertiary and cataract cultures (252 +/- 21, 169 +/- 14, 153 +/- 14 and 96 +/- 2 ng Fe/mg protein, respectively). Transferring receptor expression in lens cell cultures was reduced 10-fold within 2 days of addition of serum to cells grown in low-Fe, serum-free medium for 1 week. CONCLUSIONS: The reduction of Fe uptake by the subcultured and cataract cell lines probably reflects a decrease in transferrin receptor expression and in the activity of an alternative pathway for Fe transferrin uptake occurring over time. This reduced Fe uptake may result from long-term exposure to relatively high Fe concentration in the media. A reduction in the expression of the transferrin receptor after incubation with high concentrations of Fe supports this conclusion.

2,2'-Dipyridyl↗

PubMed1990

Ocular inflammatory effects of intravitreally injected tumor necrosis factor-alpha and endotoxin.

Intravitreal injection of human recombinant tumor necrosis factor-alpha (TNF) induced inflammation in the rabbit eye characterized by dilation of blood vessels in the iris, disruption of the blood-ocular barriers, infiltration of inflammatory cells into the anterior chamber, and accumulation of prostaglandin E in intraocular fluids. Inflammation first appeared on day 1, increased on day 2, and remained elevated on day 7. The inflammatory cell infiltrate in the anterior segment of the eye was largely monocytic on days 1 and 2; by day 7 large numbers of lymphocytes were also present. TNF-induced ocular inflammation therefore differed from that reported for intravitreally injected endotoxin in terms of time course and the types of inflammatory cells in the aqueous humor. In a series of experiments in which combinations of TNF and endotoxin were used, intravitreal injection of TNF, 24 h after a low dose of Escherichia coli endotoxin, produced no more inflammation than that produced by TNF following an injection of endotoxin vehicle. However, if TNF was injected 24 h before endotoxin, the resulting inflammation was greater than that observed in animals given TNF followed by endotoxin vehicle.

Animals↗

PubMed1993

Postvitrectomy hypotonia: the role of the vitreous and retinochoroidal lesions.

The pathomechanisms of hypotonia after vitrectomy remain obscure. To examine the possible escape of intraocular fluid through the ocular wall, hydraulic fluid conductivity was measured across preparations of retina, pigmented epithelium, and choroid isolated from rabbit eyes 1, 3, 5, or 7 weeks after the production of laser or cryopexy lesions. The hydraulic conductivity measured in a modified Fischbarg-Bourguet chamber, was 0 in controls. At 1 and 3 weeks after transpupillary diode laser coagulation of the equatorial retina, hydraulic conductivity was measurable. However, the conductivity of these preparations returned to 0 by 5 weeks. After transscleral cryopexy, conductivity remained elevated for 7 weeks. Break-up of residual cortical vitreous with hyaluronidase increased the conductivity of "mature" cryopexy lesions to the values obtained 1 week after injury. These results suggest that there is escape of fluid across retinochoroidal lesions; fluid conductance typically decreases over time; an intact cortical gel can hinder conductance and seal the retinochoroidal leak. Thus, the risk factors for hypotonia appear to include extensive retinochoroidal lesions and the absence of a normal cortical vitreous in aphakia and/or after aggressive vitrectomy.

Animals↗

PubMed1993

Intraocular extracellular cyclic nucleotide concentrations: the influence of vitreous surgery.

Levels of cAMP (23.1 pmol/ml) and cGMP (22.6 pmol/ml) are nearly equal in normal rabbit vitreous, although aqueous cAMP levels (29.9 pmol/ml) are 10 times higher than aqueous cGMP levels (2.6 pmol/ml) (P < 0.01). Intravitreal cAMP values decrease slightly 1 week after vitrectomy and lensectomy and return to normal whether the retina is attached, detached, or surgically removed. In contrast, intravitreal cGMP levels are profoundly depressed at 7 days (approximating normal aqueous levels) and are more than 50% lower than normal 30-42 days after surgery. The presence of these cyclic nucleotides in intraocular fluid and their responsiveness after surgery may signify a potential regulatory role in the physiologic responses of the eye to retinal detachment and its repair.

Animals↗

PubMed2003

[Practical advice for recovery and successful processing of anterior chamber puncture and vitrectomy samples].

For the diagnosis of unclear intraocular inflammation which threatens visual acuity and does not respond to therapy, the collection of intraocular fluid from the anterior chamber or the vitreous body is sometimes required. After surgery the correct and speedy processing of the rapidly degrading fluid determines the quality and reliability of the laboratory results. This article describes the different steps which are important after surgery to ensure optimal results for the different diagnostic laboratory procedures. If specimens are to be sent to cytology or microbiology laboratories, processing directly after surgery is necessary, while material which has to undergo PCR analysis, should remain untreated.

Biopsy↗

PubMed1998

The lens influences aqueous humor levels of transforming growth factor-beta 2.

BACKGROUND: Transforming growth factor-beta 2 (TGF-beta 2) is a pluripotent cytokine which has been suggested to play a number of roles in ocular physiologic and pathologic states. Intraocular fluid (i.o.f.) levels of TGF-beta 2 are quite high. Although the sources of ocular TGF-beta are not completely defined, the retinal pigment epithelium, the epithelium of the ciliary body and trabecular meshwork cells all secrete it. In this study we utilized canine lens and rabbit ciliary pigmented epithelial cell cultures to quantitate the in vitro secretion of TGF-beta 2. In addition, the effects of aphakia or the presence of cataractous lenses on IOF TGF-beta 2 levels were determined. METHODS: Lens and ciliary body epithelial cell culture supernatants and aqueous humors were assayed for total TGF-beta 2 levels by ELISA and bioassay. RESULTS: TGF-beta 2 accumulated in the media bathing lens epithelial cell cultures (0.7 +/- 0.03 ng/ml at day 2) and ciliary pigmented epithelial cell cultures (0.8 +/- 0.06 ng/ml at day 2) in a time-dependent manner. Surprisingly, aqueous humor from aphakic rabbit eyes contained significantly higher levels of TGF-beta 2 than their contralateral phakic controls. Furthermore, aqueous humor from canine eyes with cataracts also contained significantly higher levels of TGF-beta 2 than normal eyes. CONCLUSIONS: These results suggest that the lens secretes TGF-beta 2 and that the presence and status of the lens may influence IOF TGF-beta 2 levels.

Animals↗

PubMed1998

Correlation of varicella-zoster virus copies and final visual acuities of acute retinal necrosis syndrome.

BACKGROUND: Herpes viruses may play an important role in acute retinal necrosis (ARN) syndrome, and raised antibody titer or virus genome have been detected in intraocular fluids of patients with ARN. In spite of aggressive anti-viral therapy, the clinical courses and final visual acuities among these patients have varied. Our purpose was to estimate the amount of virus and compare it to final visual acuity in patients with ARN. METHODS: The number of varicella-zoster virus copies in aqueous and vitreous before and after administration of anti-viral therapy were estimated by polymerase chain reaction (PCR) and by semi-nested PCR in 12 eyes of 11 patients with ARN and were compared with clinical characteristics. RESULTS: Viral genome DNA was amplified in ocular fluids diluted between 10(-3) and 10(-6) in patients whose final visual acuities were 0.3 or less. Conversely, the dilution required was between 10(-1) to 10(-3) in the patients whose final visual acuities were 0.4 or better. The difference was statistically significant. Further, patients in the latter group reacted to the anti-viral drug acyclovir more promptly than did the former patients. CONCLUSION: Our results showed that final visual acuity may partly depend on the number of virus copies in ocular fluids. The number of virus copies tended to be higher in elderly or immunocompromised patients than in others, and the treatment was less efficacious in these patients.

Acyclovir↗

PubMed2005

Morphofunctional characteristics of blood mononuclear cells during in vitro culturing under dynamic conditions.

The primary culture of human blood mononuclear cells was incubated on fibrous membranes under a constant directional flow of the nutrient medium modulating intraocular fluid flow. Incubation was performed for 24, 48, and 72 h. Intracellular enzyme activity of mononuclear cells increased under dynamic conditions. Differentiation of blood monocytes and circulating fibroblast precursors into macrophageal cells and mature cells, respectively, was accelerated.

Alkaline Phosphatase↗

PubMed1992

Does the lens serve as a 'sink' for iron during ocular inflammation?

Twenty-four hours after induction of ocular inflammation by intravitreal injection of endotoxin (10 ng), the intraocular fluid (IOF, aqueous and vitreous humors) concentration of iron (Fe) increased. This was presumably due to entry of the plasma Fe-binding protein, transferrin, into the IOFs through disrupted blood ocular barriers. After 1 day of inflammation the Fe concentration in lenses from the inflamed eye was 60% greater than that measured in contralateral control lenses. By day 15, lens Fe concentration had returned to levels of the contralateral control lenses. There was a distinct relationship between the dose of endotoxin used and the amount of Fe accumulated by the lens. The Fe concentration in lenses from eyes injected with 100 ng endotoxin was 0.376 +/- 0.027 micrograms g-1 wet weight compared to 0.214 +/- 0.014 micrograms g-1 in lenses from eyes injected with 0.25 ng endotoxin. In a previous study, copper (Cu) concentration in the IOFs was elevated to the same extent as Fe in response to intravitreal injection of endotoxin. However, in the present study, lenticular Cu concentration was unaltered at the highest (100 ng) dose of endotoxin. Since the increase in lens uptake was selective for Fe, there may be a specific Fe uptake mechanism in this ocular tissue. The physiological reasons for and possible pathological consequences of such a process are discussed.

Animals↗

PubMedDate not supplied

The blood-ocular barriers.

The introduction of the concept of blood-ocular barriers in the ophthalmic literature is briefly reviewed. Two main blood-ocular barriers are proposed: the blood-aqueous barrier and the blood-retinal barrier. The blood-aqueous barrier is formed by an epithelial barrier located in the nonpigmented layer of the ciliary epithelium and in the posterior iridial epithelium, and by the endothelium of the iridial vessels. Both these layers have tight junctions of the "leaky" type. The pereability of the blood-aqueous barrier shows a significant degree of pressure-dependent diffusion associated with transport activity, resembling the standing gradient osmotic flow model. The blood-retinal barrier is located at two levels, forming an outer barrier in the retinal pigment epithelium and an inner barrier in the endothelial membrane of the retinal vessels. Both these membranes have tight junctions of the "nonleaky" type. The permeability of the blood-retinal barrier resembles cellular permeability in general, diffusion being directly related to the predominant roles of lipid solubility and transport mechanisms. Finally, the clinical significance of the blood-ocular barrier is analyzed. The metabolism of cornea and lens and the regulation of intraocular fluids are directly influenced by the blood-aqueous barrier. Similarly, an alteration of the blood-retinal barrier appears to play an important role in the development of vascular retinopathies, pigment epitheliopathies, and retinal edema.

Animals↗

PubMed1989

Active transport and metabolic characteristics of polyamines in the rat lens.

Putrescine, spermidine and spermine were transported into the rat lens against a concentration gradient. This process appeared to be energy-dependent and involved a carrier system different from those for amino acids. Competition experiments suggested that the three polyamines were transported by the same system or very similar systems. Incorporated spermine was converted to spermidine and putrescine, and spermidine was converted to putrescine. In contrast, the conversion of putrescine to spermidine and spermine, or the conversion of spermidine to spermine was not observed. Furthermore, ornithine was not utilized for the synthesis of putrescine. These metabolic characteristics of the polyamines in the rat lens were correlated with the extremely low activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase. Other enzymes of polyamine metabolisms, however, were relatively active. In conclusion, the lens has a very low ability for the de novo synthesis of polyamines. The polyamines in the lens are considered to be supplied form the surrounding intraocular fluid by an active transport system specific for polyamines.

Acetyltransferases↗

PubMed2004

Clinical characteristics of acute HSV-2 retinal necrosis.

PURPOSE: To report the clinical features and evaluate the visual outcome of eleven cases of herpes simplex virus-2 (HSV-2) related acute retinal necrosis syndrome (ARN). DESIGN: Retrospective interventional case series. METHODS: Twelve eyes of eleven patients from two European centers, diagnosed with HSV-2 related acute retinal necrosis syndrome were retrospectively reviewed. Herpes simplex virus-2 DNA was detected by polymerase chain reaction in intraocular fluids (aqueous and/or vitreous). Findings at initial examination, clinical evolution with antiviral therapy, complications and final visual acuity were evaluated. RESULTS: Herpes simplex virus-2 DNA was detected in all cases. No sample was positive for more than one virus. The mean age of disease in the first eye was 36 years (ranged from 10 to 57 years). Five patients were women and six were men. All patients were immunocompetent. Previous medical history included neonatal herpes (n = 1), previous ARN (n = 3), trauma (n = 1) and systemic corticosteroid administration before occurrence of ARN (n = 3). Preexisting pigmented chorioretinal scars were found in three cases. Patients were treated with high dose intravenous acyclovir or foscarnet +/- intravitreal ganciclovir +/- interferon. The mean follow-up was 14.5 months (from 5 to 22 months). At the end of the follow-up period, five eyes (41.7%) showed improvement of visual acuity of two or more lines. Final visual acuity was 20/60 or better in four eyes (33.3%), 20/400 or better in four eyes (33.3%) and less than 20/400 in four eyes. CONCLUSION: History of neonatal herpes, triggering events such as neurosurgery, periocular trauma, high-dose corticosteroids, and chorioretinal scars suggest that HSV-2 retinitis reflects reactivation of HSV-2 infection.

Acyclovir↗

PubMed2005

Adenoma arising from nonpigmented ciliary epithelium concomitant with neovascularization of the optic disk and cystoid macular edema.

PURPOSE: To report a case of adenoma of the nonpigmented ciliary epithelium concomitant with marked neovascularization of the optic disk and cystoid macular edema (CME). DESIGN: Observational case report. METHODS: A 34-year-old woman presented with a nonpigmented, vascularized tumor behind the iris and neovascularization of the optic disk (NVD). Visual acuity decreased gradually as a result of the development of CME. RESULTS: Iridocyclectomy to excise the tumor was performed 8 months after initial examination. Histopathologic study revealed an adenoma arising from the NPCE. The levels of vascular endothelial growth factor were significantly elevated in both aqueous and vitreous humor obtained at surgery. The NVD and CME regressed after surgery, and the postoperative visual acuity improved to 20/40. CONCLUSIONS: NVD and CME may develop secondary to adenoma of the nonpigmented ciliary epithelium. Increased levels of vascular endothelial growth factor in intraocular fluids may play a role in NVD and CME development.

Adenoma↗

PubMed2005

Incidence of intraoperative complications during phacoemulsification in vitrectomized and nonvitrectomized eyes: prospective study.

PURPOSE: To compare the incidence of intraoperative complications during phacoemulsification surgery in patients with and without prior pars plana vitrectomy (PPV). SETTING: Department of Ophthalmology, Norfolk, and Norwich University Hospital, Norwich, United Kingdom. METHODS: Prospective collection of operative complications in 2000 consecutive cataract extractions performed by 1 surgeon (R.L.B.). Details of all patients who had intraoperative complications including age at operation and sex were recorded. It was also noted whether the eye previously PPV. Complications recorded were posterior capsule rupture (PCR) with and without vitreous loss, iris trauma, loss of nuclear fragment into vitreous, and choroidal hemorrhage. RESULTS: Of 2000 eyes, 117 had previous PPV. Of these, there were 2 (1.70%) cases of PCR. There were no cases of iris trauma, choroidal hemorrhage, or dropped nucleus fragments into the posterior chamber. Nonvitrectomized eyes totaled 1883. Rates of complications were as follows: PCR without vitreous loss, 0.16%; PCR with vitreous loss, 0.53%; iris trauma, 0.16%; choroidal hemorrhage, 0.16%; and dropped nucleus fragment in the vitreous, 0.11%. CONCLUSION: Despite well-known difficulties encountered in vitrectomized eyes such as zonular damage, increased mobility of the lens-iris diaphragm, and altered intraocular fluid dynamics, the incidence of intraoperative complication rates is similar to nonvitrectomized eyes in the hands of an experienced surgeon.

Adult↗

PubMed2001

Fungal endophthalmitis following cataract surgery: clinical presentation, microbiological spectrum, and outcome.

PURPOSE: To determine the clinical presentation, microbiological spectrum, and outcome in cases of fungal endophthalmitis following cataract surgery. DESIGN: Observational case series. METHODS SETTING: Tertiary referral hospital. PATIENTS: Retrospective analysis of 27 cases of smear- and culture-proven fungal endophthalmitis. INTERVENTION: Pars plana vitrectomy in 18 eyes, where the corneal condition did not preclude the same. All eyes received intravitreal amphotericin B and dexamethasone along with systemic antifungal agents. MAIN OUTCOME MEASURES: Functional success: Final visual acuity of 3/60 or better with attached retina. Anatomical success: Final visual acuity of better than light perception with preserved anatomy of globe. RESULTS: The majority of the eyes (22 of the 27) had early onset and diffuse presentation (that is, anterior segment as well as posterior vitreous exudates). Substantial corneal involvement was seen in 14 eyes (51.85%). Aspergillus sp. was the most common isolate. Multivariate analysis using forward stepwise logistic regression showed corneal involvement as the single most important risk factor in determining final visual outcome (P =.0429). CONCLUSIONS: Early onset and diffuse presentation, which mimics bacterial endophthalmitis, stresses the importance of both bacterial and fungal cultures from intraocular fluids to reach a diagnosis apart from the clinical judgment. Corneal involvement was the most important predictor of outcome in cases of fungal endophthalmitis.

Adult↗

PubMed1997

Intraocular molluscum contagiosum after a corneoscleral laceration.

PURPOSE: To report molluscum contagiosum as a cause of severe posttraumatic intraocular inflammation. METHODS: A 9-year-old girl developed severe intraocular inflammation in the right eye after a corneoscleral laceration. She underwent vitrectomy, and bacterial and fungal cultures of intraocular fluids were negative. A pedunculated white-tan mass removed from her right optic nerve head was sent for histologic evaluation. RESULT: Histologic examination of the tissue showed stratified keratinizing squamous epithelium with intracytoplasmic inclusions consistent with molluscum contagiosum. CONCLUSIONS: It is likely that infected epithelial cells were implanted at the time of injury. Vitrectomy as debridement was curative.

Child↗

PubMed1991

Delayed-onset pseudophakic endophthalmitis.

We reviewed 19 cases of delayed-onset pseudophakic endophthalmitis in which diagnostic cultures were performed at one month or more after cataract extraction with posterior chamber intraocular lens implantation. We isolated four different organisms in these 19 cases: 12 Propionibacterium species (63%), three Candida parapsilosis (16%), three Staphylococcus epidermidis (16%), and one Corynebacterium species (5%). Because of the unusual delayed-onset features of these cases and the retrospective nature of this study, a variety of treatment regimens were used. Twelve patients had recurrence of marked inflammation despite an apparent initial cure, and ten of these patients had positive culture results on repeat examination of intraocular fluids. Nine patients continued to be treated with topical corticosteroids postoperatively to suppress low-grade inflammation. Of the 19 patients, 16 had final visual acuity of 20/400 or better. Delayed-onset pseudophakic endophthalmitis had a more favorable visual prognosis, compared to acute-onset endophthalmitis.

Adrenal Cortex Hormones↗

PubMed1980

Acute leukemic infiltration of the vitreous diagnosed by pars plana aspiration.

A 30-year-old man with acute lymphoblastic leukemia, null cell, L2 type developed a unilateral dense cellular vitreous infiltrate while in apparent remission. Cytopathologic examination of material aspirated from the vitreous established the diagnosis of lymphoblastic infiltration. Prompt radiotherapy and chemotherapy rapidly reduced the vitreous infiltration and cleared cells from the cerebrospiral fluid. Intraocular involvement by the leukemic process was the initial sign of central nervous system involvement. Acute lymphoblastic leukemia should be added to the list of lymphoproliferative disorders capable of vitreous infiltration, and which can be identified by vitreous aspiration and cytopathologic examination.

Adult↗