Dextran 40-containing incubation media: effect on lens electrolyte and water balance

Pyogenic granuloma

A retrospective review of cases of pyogenic granuloma seen at the King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia between 1984-1991 is described. Epidemiology and the factors that led to the granuloma formation were examined and only cases documented histopathologically were included in the review. Of the 110 cases, 80% developed the granuloma at the site of the previous surgery (especially entropion repair, and dacryocystorhinostomy with a stent tube or with a Jones tube) while 20% did not have a prior surgery. Recurrence occurred in 7% and these patients were in the group who had a prior surgery. Surgical procedures lead to an increased tendency for the formation of pyogenic granuloma due to different mechanisms acting via a mechanical or chemical irritation and an inhibition of re-epithelialization.

Lenticular energy metabolism during exogenous calcium deprivation and during recovery: effects of dextran-40

Phosphatic metabolites of the intact rabbit lens were quantitated as a function of time by phosphorus-31 nuclear magnetic resonance (P-31 NMR) spectroscopy during in vitro incubations at 37 degrees C in calcium-sufficient and calcium-deficient modified Earle's buffer with and without the osmotic agent, Dextran-40. Intralenticular pH was determined from the resonance shift position of inorganic orthophosphate (Pi). Incubation of lenses in calcium-deficient buffer resulted in a pronounced, time-dependent decrease in lenticular adenosine triphosphate (ATP) levels. The half-life of ATP within the lens was 11 hr under these experimental conditions. A concomitant, essentially stoichiometric increase in adenosine diphosphate and Pi levels was observed also. The other phosphatic metabolites were unaffected by exogenous calcium deprivation except for adenosine and inosine monophosphate which accumulated with time. Dextran-40 (6%), which has been shown to prevent lens swelling under these same experimental conditions, did not influence the metabolic responses of the lens to external calcium deprivation and did not facilitate subsequent restoration of lens phosphatic metabolites following restoration of a physiologic calcium concentration to the supporting medium. The Dextran-40 did, however, promote the retention of intralenticular pH environment during the experimental period. These findings suggest that the previously reported Dextran-40-dependent recovery of intralenticular sodium and potassium concentrations to control levels following 10 hr of incubation in calcium-deficient media cannot be attributed to a direct energy-sparing action of Dextran-40 on lenticular energy metabolism. Instead, the mechanistic basis for the action of Dextran-40 would appear to be related to its colloid osmotic properties and its ability to prevent lenticular swelling, which otherwise occurs in the absence of Dextran under these experimental conditions.