Fatal colchicine overdose: report of a case and review of the literature.

Colchicine poisoning is an uncommon, but potentially life-threatening, toxicologic emergency. A case is reported of a 21-year-old woman who presented to the emergency department approximately 1 hour after ingesting 30 mg of colchicine in a suicide attempt. Her clinical course included gastrointestinal distress, metabolic acidosis, pancytopenia, hypotension, adult respiratory distress syndrome, rhabdomyolysis, and hypocalcemia. Despite aggressive medical management, the patient suffered a cardiac arrest and died 8 days after the ingestion. The clinical features of colchicine poisoning are highlighted and current therapeutic options are discussed.

Long-term non-invasive measurement of intraocular pressure in the rat eye.

To study the optic neuropathy associated with glaucoma, a system for accurate, reliable, and non-invasive monitoring of intraocular pressure (IOP) is required. Of particular interest is the effect of sampling frequency on IOP. To address this issue, ten adult male brown Norway rats (group 1) were acclimatized to a 12-h/12-h light/dark cycle. On 20 days over a 30-day period, rats were anesthetized with short-acting isoflurane (Forane) inhalant anesthesia and IOP for each eye was determined by averaging 15 valid individual readings obtained with a TonoPen 2 tonometer. The last 12 measurement sessions were performed on a daily basis. To determine the minimum tolerable interval between IOP measurement sessions, a second group of 10 animals (group 2) was acclimatized in the same manner as group 1, and IOP was measured every 4 days over a period of 80 days. Next, IOP was measured every 4 days over a period of 28 days, and finally, every 2 days over a period of 19 days. For all group 1 measurements, there was no statistically significant difference between the right and left eye IOP, 14.75 +/- 1.08 (SEM) and 14.90 +/- 1.09 mm Hg, respectively. However, daily measurements produced a steady decrease in IOP and gradual weight loss. For group 2, overall mean right and left eye IOPs were 15.24 +/- 1.28 (SEM) and 15.12 +/- 1.26, respectively and were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Limbal microvasculature of the rat eye.

PURPOSE: To define the microvascular anatomy of anterior segment blood supply and aqueous drainage in the rat eye. METHODS: External limbal blood vessels were studied by direct inspection of normal, living rat eyes and eyes injected intracamerally with fluorescein dye. Intraocular connections of these vessels were then documented with scanning electron microscopy of methylmethacrylate microvascular luminal castings. RESULTS: The rat limbus possesses a circumferential vascular ring consisting of a single artery and a venous plexus. The limbal artery communicates with radial anterior ciliary arteries and with perforating arterioles arising from the long posterior ciliary arteries. The venous plexus is connected to a circumferential Schlemm's canal by numerous transcleral, aqueous-containing collector channels and drains into multiple radial veins located within the episclera. CONCLUSIONS: These findings illustrate anatomic similarities between rats and primates, both in anterior segment blood supply and aqueous humor drainage. The rat limbal artery provides collateral perfusion of the anterior segment from anterior and long posterior ciliary systems. The direct communications between identifiable external aqueous-containing veins, a circumferential episcleral venous plexus, and an internal Schlemm's canal provides the anatomic basis for producing chronically elevated intraocular pressure in rats using retrograde injection of mild sclerosing agents into the aqueous humor outflow pathways, and for administering drugs and other agents to the entire trabecular meshwork and Schlemm's canal.

Noninvasive measurement of rat intraocular pressure with the Tono-Pen.

PURPOSE: The purpose of this study was to evaluate the Tono-Pen 2 tonometer for measuring intraocular pressure (IOP) in the living rat eye. METHODS: One eye from each of 20 adult, anesthetized brown Norway rats (group 1) was cannulated and simultaneously connected to a syringe and a pressure transducer with a chart recorder. We increased IOP from 15 to 45 mmHg in 5-mmHg increments and obtained 15 consecutive readings (ignoring instrument-generated averages) at each pressure increment with a Tono-Pen 2 tonometer. To test the tonopen's ability to measure unknown IOP, transducer pressures were varied randomly in 20 additional animals (group 2), and tonopen readings were obtained in masked fashion. RESULTS: Plotting the mean tonopen readings for each animal against transducer IOP produced a regression formula of y = 4.54 + 0.79x (r = 0.98). Mean group 2 tonopen values plotted against transducer IOP yielded a regression formula of y = 4.75 + 0.78x (r = 0.94). A method comparison analysis showed that the tonopen significantly overestimates pressures at low IOP (< or = 15 mmHg), and it significantly underestimates pressures at high IOP (> or = 30 mmHg). Using two-way analysis of variance, it was determined that the group 2 data did not differ significantly from the group 1 data (P > or = 0.76). Because of this consistency, we generated a correction factor with 95% prediction intervals for Tono-Pen readings. CONCLUSIONS: The Tono-Pen 2 can be used reliably to measure IOP in the normal rat eye.