Intraocular pressure measurement in patients with instrastromal corneal ring segments.

PURPOSE: To study the measurement of intraocular pressure after implantation of Intacs (ICRS) intrastromal corneal ring segment, a device that is positioned circumferentially in the peripheral corneal stroma to correct myopia. The device changes the corneal curvature by shortening arc length. Since the ring segments are made of polymethylmethacrylate, this may cause localized changes in corneal elasticity so intraocular pressure measurement may be affected. METHODS: We measured the intraocular pressure of 12 eyes in which the ICRS had been in place longer than 6 months. We used Goldmann applanation and Tono-Pen tonometers over the central corneal and the paracentral corneal areas. We also measured the intraocular pressure with the Tono-Pen applanated directly over the intrastromal corneal ring segments. RESULTS: The resulting intraocular pressure measurements were similar for the Tono-Pen tonometer readings over the central cornea, paracentral cornea, and the Goldmann applanation tonometer readings over the central cornea (P < .01). Our measurements using the Goldmann applanation tonometer on the paracentral corneal area showed artificially elevated intraocular pressure in the 40 to 60 mmHg range. We were not able to obtain consistent results when we measured the intraocular pressure using the Tono-Pen on the corneal area directly overlying the intrastromal corneal ring segment implants. CONCLUSION: Consistent intraocular pressure measurements on eyes with the ICRS can be obtained with the Goldmann applanation tonometer over the central corneal area or with the Tono-Pen tonometer over the central or paracentral corneal areas.

High-output heart failure due to a renal arteriovenous fistula in a pregnant woman with suspected preeclampsia.

A 29-year-old nulliparous woman had development of hypertension, proteinuria, and congestive heart failure during the third trimester of her pregnancy. Her symptoms and cardiovascular changes were consistent with congestive heart failure and severe preeclampsia. The underlying pathophysiology was believed to be caused by the high-output state of pregnancy and by the increased peripheral vascular resistance of preeclampsia. The patient underwent an elective cesarean section, but her cardiovascular symptoms did not resolve. Soon after delivery, the patient was found to have an arteriovenous fistula of the right renal artery that caused the high-output cardiac state. Embolization and surgical removal of the arteriovenous fistula resulted in complete resolution of the patient's high-output heart failure. All previously reported cases of renal arteriovenous fistulas and malformations that have occurred during pregnancy are reviewed.

Effect of transforming growth factor-beta on plasminogen activator production of cultured human uveal melanoma cells.

PURPOSE: Human uveal melanoma cells have been shown to produce plasminogen activator (PA), an enzyme which can enhance tumor metastasis by promoting degradation of extracellular matrix. This study used cultured human uveal melanoma cells to determine whether the PA production of uveal melanoma cells could be modulated by transforming growth factor-beta2 (TGF-beta2), a mitogen present in the uvea. METHODS: Five different cell lines of human uveal melanoma of differing cellular morphology (2 spindle, 2 epithelioid, 1 mixed) derived from tumors from different locations in the eye (3 choroidal, 1 ciliochoroidal, 1 orbital) were grown in serum-free media, in the presence or absence of TGF-beta2 (1ng/ml to 100ng/ml). After 24 hrs, the conditioned media were collected and quantitated for PA activity by measuring the radial diffusion in fibrin-agarose clot and for total PA concentration using an enzyme-linked immunoassay. RESULTS: Among the cell lines studied, all produced PA. Cell lines derived from intraocular tumors secreted tissue-type PA (tPA), and TGF-beta2 stimulated tPA activity and secretion of cell lines containing epithelioid cells but had no effect on spindle cells. In contrast, tumor cells isolated from an orbital tumor secreted urokinase (uPA), activity and secretion of which was inhibited by TGF-beta2. CONCLUSIONS: We conclude that cultured human uveal melanoma cells produce either tPA or uPA, and TGF-beta2 can have a variable effect on PA production of these cells.

Assay of excised oxidative DNA lesions: isolation of 8-oxoguanine and its nucleoside derivatives from biological fluids with a monoclonal antibody column.

An immunoaffinity column is described that facilitates the analysis of oxidative damage products of DNA and RNA in urine, blood plasma, and medium isolated from cultures of Escherichia coli. In intact animals, lesions (adducts) excised from DNA are transported from the cell through the circulation and excreted in urine. In bacteria, DNA adducts are excreted directly into the medium. In either case, the adducts can be assayed as a measure of oxidative damage to DNA. A monoclonal antibody that recognizes 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxo8dG;8-hydroxy-2'-deoxyguanosine), a bio-marker of oxidative damage to DNA, has been isolated, and its substrate binding properties have been characterized. The relative binding affinities of this monoclonal antibody for oxo8dG, unmodified nucleosides, or derivatives of Gua made it suitable for the preparation of immunoaffinity columns that greatly facilitate the isolation of oxo8dG, 8-oxo-7,8-dihydroguanine, and 8-oxo-7,8-dihydroguanosine from various biological fluids. Quantitative analysis of these adducts in urine of rats fed a nucleic acid-free diet and in the medium from cultures of E. coli suggests that oxo8-7,8-dihydroguanine is the principal repair product from oxo8-dG in DNA of both eukaryotes and prokaryotes. The results support our previous estimate of about 10(5) oxidative lesions to DNA being formed and excised in an average rat cell per day.