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At least 325 records · Page 18Linked to original sources
PubMed1987

Clearance and localization of intravitreal liposomes in the aphakic vitrectomized eye.

The authors have examined the fate of intravitreally injected liposomes in the aphakic, vitrectomized eye of the rabbit. Liposomes labelled with 125[I]-p-hydroxybenzimidylphosphatidylethanolamine were eliminated rapidly from the intraocular fluid. Nonetheless, a significant fraction of these liposomes were found to bind to various ocular tissues including the retina, iris, sclera, and cornea. Ultrastructural studies with gold colloid-loaded liposomes revealed that retinal bound liposomes were attached to the inner limiting lamina but did not penetrate to the internal cells of the retina. Epiretinal cells bound and internalized gold colloid-loaded liposomes suggesting that these cells may be very sensitive to liposome mediated drug delivery.

Animals↗
PubMed1986

Immunological studies of uveitis. 1. Immune complex containing herpes virus antigens in four patients with acute retinal necrosis syndrome.

Four patients with acute retinal necrosis syndrome were examined. Three of them showed elevated antibody titers to varicella-zoster virus during the convalescent stage, while one of them showed an elevated titer to herpes simplex virus type 1, especially in the intraocular fluid. Also, these patients had an elevated circulating immune complex in the acute phase. Western blotting demonstrated that the immune complexes contained varicella-zoster or herpes simplex type 1 antigen, corresponding to the elevated antibody titer to either virus.

Antigen-Antibody Complex↗
PubMed1979

Does a barbiturate drug given in lethal dose enter the cornea?

We wished to see whether sodium phenobarbital (one of the commonest drugs used to commit suicide) given in a lethal dose would enter the cornea. Guinea pigs and rabbits were killed with an overdose of the drug. Using gas chromatography we were able to detect the drug not only in the vascular ocular tissues and the intraocular fluids but also in the avascular tissues such as the cornea.

Animals↗
PubMed1995

Extravascular secretion of t-PA by the intact superfused choroid.

PURPOSE: Demonstrate the continuous extravascular secretion of enzymatically active t-PA by the intact choroid. METHODS: Enucleated rat eyes were dissected under microscopic control to prepare eyecups for superfusion in a small organ culture system. Individual preparations provided access to intact retinal, retinal pigment epithelial, or choroidal surfaces in situ. Cups were superfused with oxygenated Kreb's buffer (100 microliters/minute) at 37 degrees C and pH 7.4 while suspended in a microincubator. Released t-PA activity was measured by an amidolytic assay in 1-minute overflow samples and in cup media after flow interruptions. RESULTS: Minimal basal secretion was detected in the overflow with the retina in place. Interruption of flow (10 minutes) produced a static accumulation of 0.10 +/- 0.01 IU/ml. With the retinal pigment epithelium in place after retinal removal, t-PA release was moderately accelerated. Removal of the retinal pigment epithelium to expose the Bruch's-choroidal surface produced the greatest acceleration. The 10-minute static level was 0.48 +/- 0.13 IU/ml. Release from the scleral shell after choroid removal was negligible. An acute burst release of t-PA activity (1.3 +/- 0.18 IU/ml) followed the infusion of bradykinin (5 to 20 microM) into choroidal cups. CONCLUSION: Choroid appears to be the dominant source of a continuously secreted t-PA in superfused rat eyecup organ cultures. This enzymatically active t-PA is able to pass through an apparently intact Bruch's membrane but is largely impeded by an intact retinal pigment epithelium. It is also possible that retinal pigment epithelium contains inhibitors that could reduce the released t-PA activity. The authors propose that this secretory function of the uveal tissue, which has thus far not been recognized, may be a principal mechanism for the regulation of intraocular fluid circulation and matrix remodeling by plasmin in vivo.

Animals↗
PubMedDate not supplied

[Tissue micro-diastasis and closed micro-cavities of the surgical zone in glaucoma surgery].

Investigation of methods of antiglaucoma surgery in order to control the cicatrization of filtration routes of intraocular fluid discharge is carried out at the Vladivostok Medical Institute since 1989. A total of 662 operations are analyzed, which were carried out using an original method with "inverted trapezium"-shaped dissection of the deep tissues of the sclera. A microsurgical knife designed by the authors and patented was used. The results of operations indicate their sufficiently high hypotensive effect and a low incidence of complications. The authors claim that several filtering components are advisable in antiglaucoma surgery. Simplification of the technique of antiglaucoma operation, based on the concept of micro-diastasis and micro-cavities, deserves to be further researched.

Female↗
PubMed1994

Different concentrations of vasoactive intestinal polypeptide in aqueous humor of patients with proliferative vitreoretinopathy and cataract patients.

The pathophysiological events leading to cellular proliferation in proliferative vitreoretinopathy are largely unknown. An involvement of neuropeptides in that disease has recently been discussed, as substance P was found to be highly enriched in the intraocular fluid of patients with proliferative vitreoretinopathy. In the present study, aqueous humor was analyzed for another neuropeptide, vasoactive intestinal polypeptide. Radioimmunoassay revealed significantly increased levels of that polypeptide in the aqueous humor of patients with proliferative vitreoretinopathy as compared with cataract patients who served as controls. As vasoactive intestinal polypeptide contributes to the environment of the retinal pigment epithelial cell layer and induces proliferation of these cells in vitro, this peptide may be involved in the pathogenetic mechanisms leading to cellular proliferation in proliferative vitreoretinopathy.

Aqueous Humor↗
PubMed1994

[Protein composition of the vitreous body in proliferative diabetic retinopathy. An analysis with 2-D-electrophoresis].

Gradient SDS-polyacrylamide gel electrophoresis is a useful technique for characterization of soluble human vitreous protein. However, this technique is limited in the case of suboptimal discrimination power. In this study, we used 2-D electrophoresis to analyse the protein composition of proliferative diabetic retinopathy (PDR) intraocular fluid (n = 10), and compared it with normal vitreous (n = 10) and serum (n = 10). In normal vitreous, the protein content consisted mainly of albumin, transferrin, alpha 1-antitrypsin, IgG, and prealbumin as confirmed by the comparison with protein standards. Compared to vitreous controls, all PDR samples were shown to have lower amounts of transferrin, alpha 1-antitrypsin, and prealbumin. However, the amounts of IgG were higher than in the controls. This reflects a shift to a serum-like protein profile, indicating a blood-retinal barrier breakdown. However, we also detected in PDR vitreous three protein spots in a low-molecular-weight range (5-10 kDa) none of which could be found in native vitreous or in serum. Therefore, additional local protein synthesis appears to be present in the pathogenesis of PDR. 2-D electrophoresis permits precise characterization of the soluble vitreous proteins which may be associated with the fibrovascular proliferative vitreoretinal response.

Blood Proteins↗
PubMedDate not supplied

[Focused ultrasound: experimental morphological research].

Morphology of rabbit eyes enucleated in various periods after ultrasound exposure was studied to elucidate the hypotensive effect of focussed ultrasound. Histologic findings suggest two mechanisms of focussed ultrasound effect: inhibited secretion of intraocular fluid at the expense of focal necrosis of ciliary body epithelium and creation of transscleral route of chamber fluid discharge as a result of sclera thinning at the site of intervention.

Animals↗
PubMedDate not supplied

[The late results of surgery in glaucoma over 5 years. A modification of sinusotrabeculectomy].

Modified sinusotrabeculectomy is technically simple, low traumatic, and therefore was used in elderly patients and in those with grave concomitant diseases. Sinusotrabeculectomy helps preserve the anterior chamber of the eye during surgery, that is why the postoperative period runs a more smooth course. When the anterior chamber is emptied during surgery, the anterior chamber recovers slowly in the postoperative period in elderly patients and patients with high intraocular pressure before surgery at the expense of reduced intraocular fluid production, and ciliochoroidal detachment develops more frequently.

Adult↗
PubMed1993

[Histological observations on the sclera in uveal effusion].

The author performed sclerectomy in six cases of uveal effusion syndrome and examined the excised sclera histologically. From the findings of the sclera during the surgery and histological findings of the excised sclera, uveal effusion syndrome was divided into three groups: 1) nanophthalmos, 2) non-nanophthalmos with hypertrophic sclera, 3) non-nanophthalmos with normal thick sclera. In all cases, glycosaminoglycans were found to be deposited around the scleral collagen fibers. In the nanophthalmic eyes (group 1) and non-nanophthalmic eyes with the hypertrophic sclera (group 2), much glycosaminoglycans were demonstrated around the collagen bundles and enlarged the collagen bundle spaces. In these groups, sclerectomy procedures were successful and, based on the successful result of the operation, the cause of uveal effusion was considered to be disturbance of outflow of intraocular fluid through the hypertrophic sclera. In non-nanophthalmic eyes with normal thick sclera (group 3), few glycosaminoglycans was demonstrated around the collagen bundles with less abnormality, and sclerectomy procedure was not effective. In this group, the occurrence of uveal effusion was another cause but abnormal sclera.

Adult↗
PubMed1998

Intercellular Transport-metabolic interactions in the nervous tissue developing under conditions of afferentation deficit (transplants in the anterior eye chamber).

Intercellular transport-metabolic interactions were investigated at the ultrastructural level in the grafts of the embryonic rat hippocampus and septum developing for 3 to 12 months in the anterior eye chamber of adult rats. The signs of highly increased transport from the blood capillaries ingrowing from the host's iris into the grafts (multiple pinocytotic vesicles in the endothelium and pericytes) were observed. The glial cells, which were accumulated at the graft surface, had pinocytotic invaginations and microvilli, which indicated their possible participation in the active transport of metabolites from the surrounding intraocular fluid. An increased level of direct communications, manifested in pinocytoses and large gap junctions between apposed nerve and glial cells was also present within the grafts. Moreover, microphagocytosis, as internalization of surface membrane fragments with adjacent cytoplasm of the neighbouring structure (including dendrites and axons), was often observed in the grafted tissue. It is suggested that the observed communications between neuronal and glial cells may participate in both trophic and functional interactions. An increase in the level of nonsynaptic interactions in the grafted nervous tissue may be regarded as a manifestation of the compensatory adaptation to the absence of normal tissue surrounding afferent connections and efferent targets.

Animals↗
PubMed1997

Retinal artery and vein pressures in the dog and their relationship to aortic, intraocular, and cerebrospinal fluid pressures.

The relationship between retinal arterial (Pra) and aortic (Pa) pressures is unknown, and the relationship between retinal vein (Prv) pressure and intraocular pressure (IOP) is not clear. Also unclear is the effect of cerebrospinal fluid pressure (CSFp) upon retinal venous pressure. We aimed to measure the relationships among Pra, Prv, Pa, IOP, and CSFp. Dogs were anesthetized while IOP, CSFp, and Pa were monitored. Pipettes with 2.5-micron diameter tips, connected to a servonulling pressure transducer, were used to record pressures from the retinal arteries and veins. Across a range of IOP (16-22 mmHg), CSFp (0-21 mmHg), and Pa (23-195 mmHg) the Pra = 0.72 Pa + 4.3 (r = 0.99, n = 61, P < 0.01), which suggests that the relationship between Pra and Pa is linear over a broad range of systemic blood pressures. The correlation coefficient between Prv and IOP was greater than 0.96 (P < 0.01) at all venous sites and whether IOP was greater than or less than CSFp. The transmural pressure varied along the retinal vein from 1.3 +/- 0.3 mmHg (+/-95% CI, n = 30) at 1 disk diameter from the optic disk rim to 0.3 +/- 0.2 mmHg (n = 66) at the optic disk, with a 0.9-mmHg/mm pressure gradient. These are the first measurements demonstrating a retinal vein transmural pressure close to zero.

Animals↗
PubMed1995

Modeling the effects of anterior chamber fluid viscosities on intraocular pressure following glaucoma filtering surgery.

BACKGROUND: Hypotonia, flat anterior chamber, and choroidal effusion are not infrequent and undesirable consequences of glaucoma filtering surgery. Methods developed so far to prevent or combat these complications have only been moderately successful. Viscous fluids admixed to the aqueous humor are known to influence fluid dynamics and hence intraocular pressure during variable time intervals following surgery. It was the intention of the authors to develop a mathematical model which predicts the influence of sodium hyaluronate determining the intraocular pressure following injection into the anterior chamber. METHODS: The model is based on first-order approximations and derives from the theory of rheology and fluid dynamics in narrow tubes, and is essentially based on Hagen-Poiseuille's law. RESULTS: The predictions of the model (to be published in a paper to follow) were verified in experiments on owl monkeys and showed a high degree of predictive power. CONCLUSIONS: One may conclude that sodium hyaluronate, injected once or repeatedly with fine canulas into the anterior chamber, qualifies as an important tool to maintain normal on near-normal intraocular pressure in the immediate and late postoperative phase following surgery.

Anterior Chamber↗
PubMed1989

Bacterial contamination of intraocular and extraocular fluids during extracapsular cataract extraction.

Fluid aspirated from the anterior chamber and fluid drained from the conjunctival sac during 101 extracapsular cataract operations was examined for bacterial contamination. Bacteria were grown by enrichment culture from the conjunctival sac of 90 eyes and from the anterior chamber aspirate of 29 eyes. Conjunctival fluid, stained with fluorescein, was demonstrated to flow into the anterior chamber during the aspiration stage of extracapsular cataract extraction and during intraocular lens implantation. It is suggested that this fluid from the conjunctival sac, contaminated with bacteria, routinely enters the anterior chamber during extracapsular cataract extraction and is the likely source of some cases of post-operative endophthalmitis.

Anterior Chamber↗
PubMed1988

Effect of plasma osmolality and intraocular pressure on fluid movement across the blood-retinal barrier.

The inward permeability of the blood-retinal barrier to carboxyfluorescein was determined in monkey eyes with and without rhegmatogenous retinal detachment (RD). In the absence of changes in the diffusional permeability of the retinal pigment epithelium (RPE), inward permeability changes reflect changes in fluid flow across the RPE. Intravenous injection of mannitol resulted in a 15 mosmol/kg increase in plasma osmolality which decreased inward permeability 37% in eyes with RD and 21% in eyes with vitrectomy alone. When the intraocular pressure was raised 20 mm Hg above normal, inward permeability decreased 29% in eyes with RD and 32% in normal eyes. It is concluded that fluid flow across the blood-retinal barrier is influenced by both plasma osmolality and intraocular pressure.

Animals↗