retinol-palmitate and Corneal-Ulcer

Vitamin A-deficient humans and animals are more susceptible to infections than are healthy humans and animals. This study compares the early corneal response (within 24 hours) to an experimental Pseudomonas aeruginosa infection between vitamin A deficient and control rats.. Male WAG/Rij/MCW rats were fed either a vitamin A- deficient diet (A-) or the same diet with retinyl palmitate added back in a nonrestricted manner (N) or under pair-fed conditions (A+) to yield weight-matched rats. Some A-rats were repleted wih retinyl palmitate 16 days before being killed and then given free access to the retinyl palmitate-supplemented diet (R). Twenty-four hours before being killed, the corneas of anesthetized rats were scratched and P. aeruginosa organisms were applied to the corneal surface. The rats were killed using an overdose of sodium pentobarbital. Corneas were either processed for light and electron microscopic examination or extracted for proteinase and myeloperoxidase determination. Corneal myeloperoxidase concentrations relative to neutrophil myeloperoxidase concentrations were used to determine the number of neutrophils in the cornea. Zymography was used to study caseinases, gelatinases, and plasminogen activators. Reverse zymography was used to detect proteinase inhibitors. Similar results were noted at early, mid, and late weight plateau stages of vitamin A deficiency.. Ulceration occurred within 24 hours when low numbers of P. aeruginosa (10(4) cpu) were applied topically onto scratched A- corneas, whereas no ulceration was observed in the A+, R, and N corneas. When higher numbers of P. aeruginosa (10(7)-10(8)) were applied to the scratched corneas, all corneas became ulcerated within 24 hours. The extent of ulceration in the control corneas was greater than that in A- corneas by a factor of two. Only the A- corneas contained inflammatory cells with unusual striated deposits in phagolysosomes. The total number of neutrophils in the cornea and the concentrations of caseinases, plasminogen activators, and gelatinases in the infected corneal extracts were similar; however, the concentrations of cysteine proteinase inhibitors were elevated under A- conditions.. Vitamin A deficiency alters the response of the cornea to a P. aeruginosa infection during the first 24 hours. The alterations observed are probably due to multiple factors: an insufficient tear film for bacterial clearance and migration of neutrophils, epithelial keratinization, alterations in corneal wound healing, and changes in polymorphonuclear function.

Topics: Animals; Anticarcinogenic Agents; Blotting, Western; Cornea; Corneal Ulcer; Disease Models, Animal; Disease Susceptibility; Diterpenes; Electrophoresis, Polyacrylamide Gel; Endopeptidases; Eye Infections, Bacterial; Female; Liver; Male; Neutrophils; Peroxidase; Pseudomonas Infections; Rats; Retinyl Esters; Vitamin A; Vitamin A Deficiency

Post-measles corneal ulceration resembling keratomalacia is frequently seen in young children in northern Nigeria. The concentration of retinol in plasma has been found to be depressed more by measles than by malnutrition. In order to determine whether this could be due to a specific influence of measles on the uptake, storage and release of retinol by the liver or its subsequent transport in the plasma, retinyl ester was administered parenterally to assess its effect on the concentration of circulating holo retinol-binding protein. A water-miscible preparation of retinyl palmitate was administered by intramuscular injection to well- and malnourished children with and without acute measles. In all cases, the concentration of both retinol and retinol-binding protein rose appreciably with 24 h of administration of the vitamin preparation. Thus the failure of post-measles corneal lesions to respond to orally or parenterally administered vitamin A would not appear to be due to the inability of such vitamin A to increase the level of circulating retinal in the plasma of children with measles.

Topics: Child, Preschool; Corneal Ulcer; Diterpenes; Humans; Infant; Injections, Intramuscular; Measles; Nigeria; Nutrition Disorders; Retinol-Binding Proteins; Retinol-Binding Proteins, Plasma; Retinyl Esters; Vitamin A