- Email: [email protected]
Synthesis of prostaglandins by normal and inflamed ocular tissues of the rabbit
95
ABSTRACTS
A Comparison of the Ocular Response in Man and Rabbit FolIoliving Ruby Laser Irradiation of the Iris IV. (+. UNGEIL,
N. A. P. BROWN
AND E. S. PERKINS,
Londo)t
Since the rabbit is the test animal most frequently used in experimental ophthalmology, it is important to compare the ocular response to noxious stimulation in man and rabbit. Irradiation of the pigmented rabbit iris elicit,s a pronounced defensive reaction which is mediated partly by prostaglandin and partly by an atropine-resistant neurogenic factor (Unger. Perkins and Bass. 1974j. In 27 patient volunteers with closed angle glaucoma undergoing laser iridotomy (under piloc,arpine and/or Diamox treatment) the intraocular pressure increased by a maximum of IUi:! (s.R.M.) mmHg at 40&60 min and in 15 rabbits by a maximum of 31i2 (s.n.nr.) mmHg at 10 min after one to four laser burns of the iris. In the rabbits, sodium fluorescein injected intravenously lo-15 min after irradiation rapidly entered and filled the anterior chamber, while in six patient.s there was no difference bet,ween the lasered eye and the untreated fellow eye. Pretreatment with pilocarpine and/or Diamox had no noticeable effect on the ocular changes in t.he rabbit. The results indicate that the blood-aqueous barrier in the human eye is considerably more stable tlinn in the rabbit. This may be due in part t’o anatomical differences of the ciliary processes.
REFERENCE l.nper.
W. G., Perkins,
E. S., Bass,
M. S. (1974)
Esp.
K’ye Res.
19. 367.
Synthesis of Prostaglandins by Normal and Inflamed Ocular Tissues of the Rabbit I'. HK~TTACHERJEIC,
London
Tissues from normal and inflamed eyes of rabbits were examined for prostaglandin (PG) synthetase activity using intact tissues, homogenates and microsomal preparations. Acute inflammation in the eye was induced with 1Opg s%gelEa endotoxin inject~ed into the vitreous. Twenty-four hr after endotoxin, intact iris-ciliary processes and their homogenates were incubated in vitro for 30 min at 37°C in the absence of any exogenous substrate and co-factors. .Microsomal fractions were also prepared from iris-ciliary processes and were incubated with arachidonic acid in t,he presence of co-factors. For K,, studies. concentrations of arachidonic acid ranging from 2 to 33 pn% were used. Homogenates of iris-ciliary processes of normal and inflamed eyes synthesized 2.3 and 5.6 pg respectively of PGs per g wet weight from endogenous substrate. Similar quantities of PGs were synthesized by intact tissues. Microsomes from inflamed iris-ciliary processes produced .565 ng PG/mg protein/30 min as compared with 190 ng/mg protein/30 min synthesized by normal tissues. The apparent K, of PG-synthetase from inflamed iris-ciliary processes was found to be lower than that of normal PG-synthetase. It is suggest,ed that PG-synthetase activity is modulat,ed during endotoxin-induced inflammation.
Scanning and Transmission Electron Microscopic Study of Alkali-Burned Cornea (4. REXARD,
$2. HIRSCH,
0.
MARQTET
AND
Y.
POULIQITS.
I'ctri.~
Rabbit cornea was burned with 0.5 N-sodium hydroxide for 1 min and washed aith sa,lim. Samples were taken on the lst, 3rd, 5th, 12th. 21st, 30th and 60th days and the epithelial surfaces were examined by SEX and T.E.M. Initially, there was total destruction of both epithelium and endothelium. Regeneration of the epithelium appeared at the periphery of the cornea starting from the conjuctival cells. Five days after injury the epithelium covered the surface but the cells were separated by large intercellular spaces and were joined only by desmosomal attachments. Some goblet cells also migrate with epithelial cells and were found in places on the cornea. Twelve days after burning the epithelium appeared normal. On the endothelial side. t,here were. at the outset, only fibrin and inflammatory cells on the naked surface of Descemet’s membrane. On the fifth day, new, fibroblast-like cells appeared. coming from the cornea1 periphery. These differentiated unto normal endothelial cells in small areas, but the covering of Descemet’s membrane was not complete until the 21st day. New wax-es of fibroblsst-like cells grew over the first layer forming a retro-cornea1 membrane.
ABSTRACTS
A Comparison of the Ocular Response in Man and Rabbit FolIoliving Ruby Laser Irradiation of the Iris IV. (+. UNGEIL,
N. A. P. BROWN
AND E. S. PERKINS,
Londo)t
Since the rabbit is the test animal most frequently used in experimental ophthalmology, it is important to compare the ocular response to noxious stimulation in man and rabbit. Irradiation of the pigmented rabbit iris elicit,s a pronounced defensive reaction which is mediated partly by prostaglandin and partly by an atropine-resistant neurogenic factor (Unger. Perkins and Bass. 1974j. In 27 patient volunteers with closed angle glaucoma undergoing laser iridotomy (under piloc,arpine and/or Diamox treatment) the intraocular pressure increased by a maximum of IUi:! (s.R.M.) mmHg at 40&60 min and in 15 rabbits by a maximum of 31i2 (s.n.nr.) mmHg at 10 min after one to four laser burns of the iris. In the rabbits, sodium fluorescein injected intravenously lo-15 min after irradiation rapidly entered and filled the anterior chamber, while in six patient.s there was no difference bet,ween the lasered eye and the untreated fellow eye. Pretreatment with pilocarpine and/or Diamox had no noticeable effect on the ocular changes in t.he rabbit. The results indicate that the blood-aqueous barrier in the human eye is considerably more stable tlinn in the rabbit. This may be due in part t’o anatomical differences of the ciliary processes.
REFERENCE l.nper.
W. G., Perkins,
E. S., Bass,
M. S. (1974)
Esp.
K’ye Res.
19. 367.
Synthesis of Prostaglandins by Normal and Inflamed Ocular Tissues of the Rabbit I'. HK~TTACHERJEIC,
London
Tissues from normal and inflamed eyes of rabbits were examined for prostaglandin (PG) synthetase activity using intact tissues, homogenates and microsomal preparations. Acute inflammation in the eye was induced with 1Opg s%gelEa endotoxin inject~ed into the vitreous. Twenty-four hr after endotoxin, intact iris-ciliary processes and their homogenates were incubated in vitro for 30 min at 37°C in the absence of any exogenous substrate and co-factors. .Microsomal fractions were also prepared from iris-ciliary processes and were incubated with arachidonic acid in t,he presence of co-factors. For K,, studies. concentrations of arachidonic acid ranging from 2 to 33 pn% were used. Homogenates of iris-ciliary processes of normal and inflamed eyes synthesized 2.3 and 5.6 pg respectively of PGs per g wet weight from endogenous substrate. Similar quantities of PGs were synthesized by intact tissues. Microsomes from inflamed iris-ciliary processes produced .565 ng PG/mg protein/30 min as compared with 190 ng/mg protein/30 min synthesized by normal tissues. The apparent K, of PG-synthetase from inflamed iris-ciliary processes was found to be lower than that of normal PG-synthetase. It is suggest,ed that PG-synthetase activity is modulat,ed during endotoxin-induced inflammation.
Scanning and Transmission Electron Microscopic Study of Alkali-Burned Cornea (4. REXARD,
$2. HIRSCH,
0.
MARQTET
AND
Y.
POULIQITS.
I'ctri.~
Rabbit cornea was burned with 0.5 N-sodium hydroxide for 1 min and washed aith sa,lim. Samples were taken on the lst, 3rd, 5th, 12th. 21st, 30th and 60th days and the epithelial surfaces were examined by SEX and T.E.M. Initially, there was total destruction of both epithelium and endothelium. Regeneration of the epithelium appeared at the periphery of the cornea starting from the conjuctival cells. Five days after injury the epithelium covered the surface but the cells were separated by large intercellular spaces and were joined only by desmosomal attachments. Some goblet cells also migrate with epithelial cells and were found in places on the cornea. Twelve days after burning the epithelium appeared normal. On the endothelial side. t,here were. at the outset, only fibrin and inflammatory cells on the naked surface of Descemet’s membrane. On the fifth day, new, fibroblast-like cells appeared. coming from the cornea1 periphery. These differentiated unto normal endothelial cells in small areas, but the covering of Descemet’s membrane was not complete until the 21st day. New wax-es of fibroblsst-like cells grew over the first layer forming a retro-cornea1 membrane.