Blood-retinal and blood-aqueous barrier permeability, lens autofluorescence and transmission in insulin-dependent diabetic youngsters.

The permeability of the blood aqueous and blood retinal barrier, the lens transmission, and the lens autofluorescence were measured by fluorophotometry in 7 diabetic youngsters treated by conventional therapy (mean age, 10.9 +/- 4.4 years), 9 diabetic youngsters treated by continuous s.c. insulin infusion (mean age, 12.3 +/- 5.0 years), and 13 healthy controls (mean age, 12.4 +/- 5.1 years). The mean permeability value for the blood retinal barrier of the diabetic juveniles did not differ significantly from that of the controls (P greater than 0.4), and no correlation with metabolic control (HbAlc) or duration of diabetes was found (P greater than 0.1). No differences in lens transmission larger than 4% were found. The mean value of lens autofluorescence corrected for normal age-dependency was found to correlate with the metabolic control: an increase of mean HbAlc by 1% resulted in an extra increase of autofluorescence by 11% (P = 0.002). This result suggests that good metabolic control can suppress excess lens autofluorescence, a precursor of cataract.

Uptake and clearance of 5-fluorouridine following subconjunctival and intravitreal injection.

Described are some pharmacokinetic parameters for 5-fluorouridine, a potentially useful intermediate metabolite of 5-fluorouracil (5-FU), following subconjunctival and intravitreal injection in the pigmented rabbit. Immediately following a 500 microgram intravitreal injection of 3H-5-fluorouridine, a peak ipsilateral vitreous concentration of 308 micrograms/ml was measured. This decreased to 199 micrograms/ml at 2 hours, 33 micrograms/ml at 12 hours and 4.4 micrograms/ml at 24 hours, indicating that 5-fluorouridine is cleared from the vitreous at a rate similar to 5-fluorouracil. Aqueous concentrations in the ipsilateral eye reached a maximum at 6 hours (9.6 micrograms/ml) and decreased to 0.8 micrograms/ml at 24 hours. Following subconjunctival injection of 5 mg 3H-5-fluorouridine (0.5 ml), peak ipsilateral anterior chamber concentration of 10.7 micrograms/ml was measured 1 hour after injection and decreased to 2.4 micrograms/ml after 12 hours. Maximum vitreal concentrations of 1.7 micrograms/ml were measured 12 hours after injection.

[Cell populations of transplantable murine tumors of various degrees of histogenesis during their proliferation in the anterior chamber]. / Kletochnye populiatsii perevivnykh myshinykh opukholei raznogo gistogeneza pri ikh proliferatsii v perednei kamere glaza.

Six transplantable murine tumors of different histogenesis were investigated after transplantation to subcutaneous connective tissue (SCT) and the eye anterior chamber (EAC). Cell morphology was studied using light microscopy. DNA contents in the nuclei of tumor cells were investigated with flow cytometry technique. LDH isoenzymes were studied using electrophoresis in polyacrylamide gel. In the case of tumors with near diploid modal class, a redistribution of LDH isoenzyme activity and an increase in morphological differentiation level were obtained. In the case of tumors with modal class differing from the diploid one, a morphological structure changes were revealed, but there were no differences in LDH isoenzyme activity. The data obtained show that the capability of increasing morphological and biochemical differentiation level after cultivation in the EAC of murine transplantable tumors remains even on the late stages of progression in tumors of different histogenesis with near diploid value of modal class.

Diagnosis of anterior chamber metastasis by serologic marker found during anterior chamber paracentesis.

A 29-year-old man developed anterior uveitis unresponsive to intensive topical and systemic therapy. He had recently completed a course of chemotherapy with apparent response and resolution of metastasis from a mixed germ cell tumor (embryonal carcinoma and seminoma). Anterior chamber paracentesis was nondiagnostic on two occasions for metastatic cells. At the time of his second paracentesis a tumor marker, human chorionic gonadotropin-beta subunit, was used to confirm the diagnosis of anterior chamber metastasis to the eye.

Factors associated with poor predictability by intraocular lens calculation formulas.

In this study, we evaluated and compared two groups of posterior chamber intraocular lens (IOL) implantation cases. One group consisted of patients whose postoperative refraction was accurately predicted by IOL calculation formulas, while the other group included patients whose postoperative refraction was poorly predicted by the same formulas. We found that although postoperative astigmatism was greater in the poorly predicted group, preoperative to postoperative changes in astigmatism did not differ between the two groups. The poorly predicted group also had a shorter average axial length, a greater proportion of females, and an increased variability in most of the measurements we performed. The two groups did not differ significantly in terms of measured postoperative anterior chamber depth, age at the time of the surgery, IOL power and style implanted, complication rate, or preoperative corneal integrity.

Ocular penetration of (125I)IVDU, a radiolabeled analogue of bromovinyldeoxyuridine.

Following topical application of (125)IVDU, the radiolabeled analogue of bromovinyldeoxyuridine ([E]-5-[2-bromovinyl]-2'-deoxyuridine), as 0.5% or 0.3% eyedrops, to rabbits, (125I)IVDU appeared in the anterior chamber fluid at drug levels well above the minimum concentration (0.01 microgram/mL) required for inhibition of herpes simplex virus type 1 replication. These findings are consistent with the efficacy of 0.5% bromovinyldeoxyuridine eyedrops in the topical treatment of herpes simplex uveitis.

A fresh look at iontophoresis.

The rate of penetration of fluorescein and gentamicin ions into the anterior chamber of the rabbit was increased more than 100-fold by the passage of 1 mamp; the amount of drug that penetrates is better controlled by iontophoresis than by instillation. The potential value, the safety and the limitations of this procedure are discussed, and a theoretical basis for the increase is provided. Practical methods of using iontophoresis in the clinic are described. A 30-s application should result in a therapeutic level of the antibiotic in the anterior segment over a 12-hour period in eyes with an intact epithelium.

Distributions of 35S-sulfate and 3H-glucosamine in the angular region of the hamster: light and electron microscopic autoradiography.

The distribution of 35S-sulfate and 3H-glucosamine in the angular region of the hamster was studied by light and electron microscopic autoradiography following intraperitoneal injection of these compounds to hamsters. Exposed silver grains of 35S-sulfate were concentrated in the trabecular meshwork, sclera, and cornea, and grains of 3H-glucosamine were localized in the trabecular region. The radioactivity of both isotopes was observed in the Golgi apparatuses of the endothelial cells of the angular aqueous plexus and the trabecular meshwork. The grains were noted over the entire cytoplasm, except for the nucleus, and then were incorporated into the amorphous substance and collagen fibers in the region adjacent to the angular aqueous sinus. These results suggest that endothelial cells in the angular region synthesize and secrete the sulfated glycosaminoglycans and hyaluronic acid.

[Hepatitis B surface antigen in a donor's eye]. / Hepatitis B-Surface Antigen im Spenderauge.

In ophthalmology not too much attention is given to infectious disease due to hepatitis B virus. On enucleated donors' eyes with known hepatitis B viraemia we determined the distribution of HBsAG (hepatitis B surface antigen). Virus-associated antigen could not only be demonstrated in vascularized structures, but also in corneal epithelium and anterior chamber fluid.

Ocular neuropeptides.

This article deals with the neuropeptides found in the eye and their actions. Substance P (SP) and VIP have been found in the anterior chamber of the eye. Here SP is localized in the sensory nerves of the sclera, cornea, iris, ciliary body and ciliary processes. It is supposed to be a sensory transmitter but can also be liberated by peripheral nerve endings as a response to various trauma. When this happens in the eye, for instance, after irritation of the Vth cranial nerve, SP causes an intense and long lasting miosis and may have some further actions as well. VIP has been demonstrated in nerves (probably cholinergic) of the posterior choroid and ciliary body. It is a potent vasodilator and may regulate choroideal blood flow. The retina is especially rich in different neuropeptides. SP, VIP, neurotensin, enkephalin, somatostatin, glucagon and gonadotropin-releasing hormone have all been demonstrated in the inner plexiform layer of the retina of various animal species. Specific information about the physiological role of retinal neuropeptides is still scarce but research is in progress. Considering the clinical significance of the new information about ocular neuropeptides, SP seems to be the most important substance. Recently a synthetic SP antagonist was reported to block the inflammatory response in the rabbit eye, which suggests a clinical use for this type of compounds.

Diagnosis and management of lens-induced glaucoma.

Lens-induced glaucoma may occur as either secondary angle-closure or open-angle glaucoma. Dislocation or swelling of the lens can cause pupillary block and subsequent angle-closure glaucoma. Leakage of soluble lens proteins from a relatively intact cataractous lens can result in a severe secondary open-angle glaucoma (phacolytic glaucoma). Heavy molecular weight protein, believed to be of lens origin, has now been identified in 12 of 12 anterior chamber specimens from such patients. This liberated lens protein can directly obstruct the trabecular outflow pathways. After extracapsular cataract surgery or after lens trauma, liberated fragments of lens material may mechanically impair the drainage of aqueous humor through the outflow channels (lens particle glaucoma). The diagnosis and management of these different lens-induced glaucomas are reviewed. With proper recognition, these glaucomas are promptly cured by the surgical removal of the lens (material).

Ocular reaction to the use of wet-pack versus dry-pack intraocular lenses.

This study confirms preliminary indications that dry-pack sterilized lenses cause a more marked anterior chamber reaction than wet-pack sterilized lenses during the immediate post-op period. After the first two weeks, this difference is not evident.

Fluorophotometry and the blood-ocular barrier in experimental systemic hypertension.

Fluorophotometry was used to evaluate alterations in the blood-ocular barrier to fluorescein in rats with experimental hypertension. One hour after intravenous injection of fluorescein, 16.6 mg/kg, concentrations in the anterior chamber were increased from mean normotensive values of 135 micrograms/mL to 299 micrograms/mL (P = .005) in animals with severe hypertension. Fluorescein concentrations in the vitreous also were increased from 50 micrograms/mL in normotensive rats to 109 micrograms/mL (P = .005) in hypertensive animals. With increasing duration of systemic pressures above 160 mm Hg, anterior chamber fluorescein concentrations rose from base-line of 135 micrograms/mL to 210 micrograms/mL after one to four weeks of hypertension, and to 394 micrograms/mL after five to eight weeks (P = .005). Similarly, vitreous concentrations increased from baseline of 50 micrograms/mL to 76 micrgrams/mL and 136 micrograms/mL (P = .005) after the shorter and longer periods of hypertension. Control of hypertension with return of systolic pressure to below 120 mm Hg caused a reversal of the abnormal fluorescein permeability.

Characterization of bovine anterior-lens-capsule basement-membrane collagen. 2. Segment-long-spacing precipitates: further evidence for large N-terminal and C-terminal extensions.

Collagen extracted from bovine anterior lens capsule basement membrane under minimally degradative conditions can be precipitated in the form of segment-long-spacing crystallites. Positive and negative stain preparations of these precipitates, using uranyl acetate, show the crystallites to have an asymmetric band pattern, indicating unidirectional orientation of all molecules in each crystallite. Non-banded globular masses appear at both ends of most of the crystallites, giving the segment-long-spacing aggregates the form of dumbells, with a total length of 300 nm. Repeated pepsin digestion removes first one then both globular regions leaving the helical region intact but with a length still equal to 300 nm. It thus appears that the pepsin-susceptibile protein is folded back over and covers the ends of the helical regions. Preparations with the most intact end regions tend to aggregate in fibrous segment-long-spacing form, that is, in end-interacted strings or nets. The very prominent molecular end-region interaction suggests a similar filamentous but non-periodic organization within native basement membrane.

Intraocular penetration of subconjunctivally administered 14C-fluorouracil in rabbits.

Fluorouracil is given for a variety of neoplasms by various administrative routes. Toxicity of susceptible normal tissue limits systemic dosage, but at this level intraocular tissue may not receive tumor-inhibiting concentrations. Subconjunctival administration of 6.25 mg of 14C-fluorouracil in 0.5-mL dosages resulted in a peak anterior chamber concentration of 69.5 micrograms/mL and a peak vitreous concentration of 10.5 micrograms/mL over the 12 hours tested. This resulted in no visible ocular damage. The intraocular levels achieved were greater than the concentration reported to inhibit selected tumors. The total dosage administered was considerably below the level of systemic toxicity.