Phosphate-buffered Solution Control Research Articles

A New Classification System Predicting Keratomalacia After Trauma in Vitamin A Deficiency

The purpose of this study was to develop a classification system to predict keratomalacia after trauma in vitamin A-deficient eyes and to determine whether citrate impedes polymorphonuclear leukocyte infiltration into the cornea, thus preventing keratomalacia. Preliminary classification studies showed that a 7.0-mm corneal epithelial scrape, before clinical findings of corneal xerosis, did not induce keratomalacia. Primary studies were conducted concurrently on the same animals to develop the classification system and test the effect of citrate in vitamin A deficiency. A 7.0-mm corneal epithelial scrape was performed on vitamin A-deficient eyes in various stages of corneal xerosis and treated as follows. Experiment 1: group 1, 10% citrate drops; group 2, phosphate buffer solution (PBS) drops; experiment II: group 3, drops and subconjunctival injection of 10% citrate; group 4, drops and subconjunctival injection of PBS. Corneal abrasion in eyes with 2+ corneal xerosis yielded keratomalacia in 50% of cases; the remainder healed with xerotic epithelium. Eighty-three percent of eyes with > 2+ xerosis developed keratomalacia after corneal abrasion, whereas only 7.1% of eyes with < 2+ xerosis advanced to this stage. In experiment I, 27% of citrate-treated eyes and 38% of PBS-treated eyes developed keratomalacia (not significant). In experiment II, two of six citrate-treated eyes perforated and one eye developed keratomalacia. One of six control PBS eyes perforated and four developed keratomalacia. We correlated the degree of corneal xerosis with the occurrence of keratomalacia after corneal trauma. This led to the development of a classification scale that is of research and clinical significance. Additionally, citrate did not significantly reduce keratomalacia or perforation in the vitamin. A-deficient eye.

Topical and Subcutaneous ??-Interferon Fails to Suppress Corneal Neovascularization

Corneal neovascularization is a potentially blinding complication of a variety of corneal disorders. alpha-Interferon has been shown to inhibit endothelial cell migration and proliferation. It has been used successfully in the treatment of pediatric pulmonary hemangioma and hairy cell leukemia. This study was undertaken to evaluate the effect of topical and subcutaneous (s.c.) alpha-interferon on corneal neovascularization. Corneal neovascularization was induced in 40 male New Zealand white rabbits by placing silk sutures (7.0) bilaterally in each rabbit eye at the 3 and 9 o'clock positions of the cornea, 3 mm from the limbus. Animals were randomized into two main treatment groups for topical (group 1) and s.c. (group 2) administration of interferon. Group 1 (n = 24) was then randomized into four subgroups and treated daily with topical doses of (a) rabbit specific alpha-interferon; (b) alpha-interferon plus 1% prednisolone acetate; (c) 1% prednisolone acetate; and (d) buffered phosphate control. Group 2 (n = 16) was randomized into two subgroups that received s.c. injections every other day of (a) alpha-interferon and (b) phosphate buffer. Rate of corneal neovascularization was documented photographically, with the end-point being the arrival of vessels at the suture for each group. The results of this study indicated that at the concentration and dosing regimens we used, neither topical nor s.c. alpha-interferon inhibits the rate of corneal vascular growth significantly when compared with our phosphate buffered solution control group (p = 0.88 and p = 0.84, respectively). Prednisolone acetate appeared to be the most effective in inhibiting corneal neovascularization (p = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of bovine chorioallantoic membrane explants with three strains of Brucella abortus

Summary Chorioallantoic membrane (cam) explants were used to determine the in vitro growth and cytotoxic potential of 3 strains of Brucella abortus. Bovine cam explants were inoculated with 2 × 107 colony-forming units of the pathogenic strain 2308, attenuated strain 19, or the rough strain RB51 of B abortus. After inoculation, the explants were harvested and examined at 2 or 4 hours, 12 or 14 hours, and 24 or 26 hours of incubation. Bacterial growth associated with each explant was determined by counting colony-forming units. The degree of cellular damage in each explant associated either with bacterial growth or bacterial toxins was evaluated by morphometric analysis after trypan blue staining. Significant differences were not detected in the numbers of bacteria of any strain of B abortus in the cam explants at comparable time intervals. The rate of growth of the bacteria in cam explants was higher between 2 and 12 hours after inoculation than between 12 and 24 hours after inoculation. Cytotoxic effects associated with strain 2308 were significantly (P &lt; 0.05) greater than that caused by other strains. Cytotoxic effects associated with strain 19 and rough strain RB51 were similar, and both were significantly (P &lt; 0.05) greater than the phosphate buffer solution control. Chorioallantoic membrane explants inoculated with a filtrate of heat-killed strain 2308 induced minimal cellular damage, compared with that caused by the viable bacteria. These results indicated that the number of B abortus in trophoblasts was independent of the degree of cellular damage.