Devorah Khorazo

The Bacterial Flora of the Normal Conjunctiva

The results of 1,122 preoperative cultures of noninflamed conjunctivae are summarized. Staphylocci and diphtheroids are the most frequent bacterial habitants of the normal conjunctiva. Other organisms occur in a relatively small percent of cases. The incidence of diphtheroid organisms increases markedly with advancing age, the increase being most pronounced in the 30- to 50-year group. Pneumococci and green streptococci occur most frequently in children under five. From the Laboratory of Bacteriology of the Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, and the Institute of Ophthalmology of the Presbyterian Hospital, New York City.

Precipitins in the Ocular Tissues of Rabbits Generally and Locally Immunized with Crystalline egg Albumin

The precipitin concentrations in the ocular fluids and tissue juices following general and local immunization with crystalline egg albumin were measured by a capillary technique utilizing minute quantities of reagents. Precipitins were present only in the serum, corneae, sclerae, and conjunctivae of generally immunized rabbits. Of the tissues, the corneal juice contained the greatest precipitin concentration; about one fourth that of the serum. Precipitins were never detected in the aqueous fluids of generally immunized rabbits until after an inflammation of the eye had occurred. Following the injection of egg albumin into the anterior chambers precipitins were found in the tissues of the injected eyes but not in those of the noninjected eyes. The highest concentration was present in the corneal juice. The antibodies appeared in the tissues before they could be detected in the serum and remained in much higher concentration there. No precipitins could be detected in the aqueous fluids of eyes into whose anterior chamber egg albumin had been injected until after they had appeared in the serum and until after a local inflammation had occurred. Following the injection of egg albumin into the cornea the precipitins could be detected in that tissue before they could be found in the serum or elsewhere and they remained there in much higher concentration. The removal of the corneal epithelium and endothelium before the tissue juice was expressed did not affect the precipitin titer of the juice. When only one cornea of each animal was injected no precipitins could be detected in the uninjected corneae. These experiments strongly suggest that the precipitins were formed locally in the connective tissue of the corneal stroma. From the Departments of Ophthalmology and Bacteriology, College of Physicians and Surgeons, Columbia University, and the Institute of Ophthalmology, Presbyterian Hospital, New York City. Read before the Association for Research in Ophthalmology, in Kansas City, Missouri, May 12, 1936.

A Method of Obtaining Undiluted Tissue Juice for the Study of Tissue Antibody Titer

The problem of obtaining suitable material for the determination of the antibody content of tissues or organs has usually been met by grinding the tissues with sand and extracting in a solvent, either physiological saline alone or equal parts of the saline solution and glycerine. The method is tedious and the material obtained has already undergone dilution which is not always desirable. The ease with which tissue juices are obtained by pressure in certain experiments carried out by Dr. Foster of the Department of Biochemistry suggested to us the possibility of extracting organs by this procedure for use in immunological experiments. The method consists in placing the tissue in an hydraulic press and extracting its fluid content under a pressure of approximately 16,000 pounds per square inch. The method may be used for any organ but is particularly serviceable in extracting skin and subcutaneous tissue where the large amount of connective tissue makes other methods of extraction difficult. The tissue to be extracted is cut into pieces and mixed with a large volume of portions of filter paper about 1 cm. square. The whole mixture is cut up further until it consists of a grumous mass of filter paper which has absorbed all the bits of tissue to it. The filter paper offers traction and prevents the tissues from sliding out of the press. This mixture of filter paper and tissue is then wrapped in a piece of cheese cloth and is ready to be pressed for the extraction of its fluid content. The press used is an hydraulic press manufactured by Fred S. Carver of New York City, capable of exerting a pressure of 20,000 pounds per square inch.

Experiments on Purification of Bacteriophage, and a Respiratory Pigment in Escherichia Coli Communis

During a study of the bacteriolytic enzyme, lysozyme, 1 we wished to compare its properties with those of bacteriophage. The method used for the purification of lysozyme was not applicable to bacteriophage because of the extreme sensitivity of phage to the common organic solvents. Previous efforts at purification of bacteriophage have usually employed physico-chemical methods: ultrafiltration through membranes of graded porosity, 2 adsorption, 3 and more lately centrifugation. 4 In the present work the removal of undesired culture medium and bacterial components was attempted by chemical methods and the behavior of phage toward some chemical agents was observed. The phage and coli strains here used were obtained from Dr. M. Holden, of the Department of Bacteriology. The organism gives the sugar reactions of Escherichia coli Communis. The phage was isolated from a normal stool several years ago and has been propagated since on the coli strain. In obtaining phage for concentration an 18-hour culture was inoculated into a liter of beef heart infusion broth (pH 7.4-7.6) and incubated at 37° until clouding was plainly visible. A small amount of the phage broth was added and the flask was incubated another 18 hours. Complete clearing usually occurred and the broth was filtered through a Berkefeld N filter. In titrating the various phage preparations 0.5 cc. of progressive dilutions were placed in sterile Wassermann tubes and 4.5 cc. portions of a 3 to 4-hour culture of the organism were added. A control tube of 0.5 cc. of sterile broth with the culture was used with each series. After 18 hours at 37° readings were made, the highest dilution giving complete clearing being designated as the end point.