Effects of gamma-interferon on keratocyte-induced collagen gel contraction and keratocyte proliferation.

PURPOSE: Gamma-interferon has been shown to be an effective immunoregulatory polypeptide that can modulate fibroblastic response. We investigated the effects of gamma-interferon on keratocyte proliferation and keratocyte-induced collagen gel contraction. METHODS: Gamma-interferon in concentrations of 0.01, 1, 100, and 1000 U/ml of media was added to keratocytes embedded in polymerized type I collagen and the gel area was measured after 5 days with an image analysis system. The rate of keratocyte proliferation within and outside the collagen gel under the influence of gamma-interferon was also investigated. RESULTS: Keratocyte-induced collagen gel contraction was significantly inhibited at all concentrations above 0.01 U/ml. The keratocyte proliferation was not affected by low and moderate concentrations and was significantly stimulated at concentration of 1000 U/ml. CONCLUSION: Keratocyte-induced collagen gel contraction is inhibited by gamma-interferon and the mechanism of this effect is not inhibition of keratocyte proliferation by gamma-interferon.

Dichlorotriazinyl aminofluorescein inhibits human keratocyte proliferation in vitro.

PURPOSE: Dichlorotriazinyl aminofluorescein (DTAF) has been used to stain corneal stromal collagen as part of in vivo experimentation. Toxicity of this drug, if present, might alter the observed wound healing. To determine if this drug has any deleterious effect on keratocytes, we evaluated it in vitro. METHODS: Human keratocytes in 96 well plates were exposed to different concentrations of DTAF (10e-7, 10e-6, 10e-5, 10e-4, 10e-3, 10e-2, and 10e-1 mg/ml of media). Exposure times of 1 and 24 hours at each concentration of DTAF were evaluated. The cell number was measured 1 and 3 days after exposure to the drug using a coulter-counter and a hemocytometer. RESULTS: The proliferation of keratocytes after 24 hours of exposure to the drug was inhibited in a dose dependent manner by DTAF, but 1 hour exposure of keratocytes to the drug did not inhibit keratocyte proliferation. CONCLUSION: These results suggest that DTAF has inhibitory effects on human keratocyte proliferation after 24 hours of exposure, while exposure limited to 1 hour does not induce such a change.

Insulin-requiring diabetes mellitus, hyperlipidemia, and anginal chest pains as prominent features of pheochromocytoma.

We report the case of a 60-year-old man with recent onset of poorly controlled diabetes mellitus, frequent anginal chest pains, paroxysmal hypertension, hyperlipidemia, and mild renal insufficiency. The patient was found to have pheochromocytoma of the left adrenal gland, resection of which resulted in total resolution of diabetes, hypertension, chest pain, hyperlipidemia and renal failure.

The effect of dichlorotriazinyl aminofluorescein on human keratocytes in vitro.

Dichlorotriazinyl aminofluorescein (DTAF) has been used to stain corneal stromal collagen as part of in vivo animal experiments for many years. Toxicity of this drug, if present, might alter the observed wound healing. To determine if this drug has any deleterious effect on keratocytes, we evaluated it in vitro. Human keratocytes prepared in 24-well plates were exposed to varying concentrations of DTAF (10(-4), 10(-3), 10(-2), 1, 10, 10(2) micrograms/ml). Exposure times of 1 hour and 24 hours at each concentration of DTAF were evaluated. The cell number was measured 1 and 3 days after initiation of exposure to DTAF using a Coulter counter. Keratocyte proliferation was not affected by 1-hour exposure to DTAF, but keratocyte proliferation measured 3 days after initiation of exposure to DTAF for 24 hours was inhibited in a dose-dependent manner (p = 0.02) and was significantly inhibited at concentrations of 10 and 100 micrograms/ml (p < 0.05). Fluorescent microscopy showed binding of DTAF to keratocytes. We have demonstrated that prolonged exposure to DTAF inhibits proliferation of cultured keratocytes. These results suggest that DTAF-induced cytotoxicity may alter net production of collagen in the corneal stroma in animal models.