Effect of Actinomycin D on Virus-induced Ribonucleic Acid Polymerase Formation in Foot-and-Mouth Disease Virus-Infected Baby Hamster Kidney Cells

Actinomycin D, at a concentration that inhibits cellular ribonucleic acid (RNA) synthesis, inhibited the production of foot-and-mouth disease virus-induced RNA polymerase in baby hamster kidney cells. Inhibition was proportional to exposure time and reached 85% when actinomycin D was added 90 min before infection. Polymerase production was inhibited to the same extent in growth and minimal media, and the kinetics of its appearance were slightly different than in untreated cells. Enzyme preparations from actinomycin-treated cells having one-third to one-tenth the activity of untreated samples gave products with RNA profiles similar to those of controls. The 37S viral peak, 20S ribonuclease-resistant peak, and 26 to 28S peaks were present in all cases. Actinomycin D did not consistently inhibit virus production in either medium. Insulin did not prevent the actinomycin induced inhibition of polymerase and virus production from occurring.     

Clinical Use of a New Mitral Disc Valve

A disc valve of new design was used successfully for the replacement of the mitral valve in patients with rheumatic mitral valve disease. This valve would appear to have the following advantages over the mitral ball valve prosthesis:• Lower left atrial pressure after replacement.• Elimination of the hazard of left ventricular outflow tract obstruction with mitral valve replacement.• Decreased incidence of thromboembolization.• Abolition of possibility of ventricular septal irritation.Despite the better outlook for this valve compared with the ball valve for mitral valve substitution, the mitral valve should always be repaired whenever feasible. Repair is possible in the majority of patients.     

Oxyphenbutazone (Tandearil?) in Rhinoplasty—A Clinical Evaluation of Effectiveness

To evaluate the effectiveness of Oxyphenbutazone as an anti-inflammatory agent, a double-blind study of Oxyphenbutazone and a placebo in a group of 42 patients who had nasal cosmetic operations involving osteotomy was carried out. The observations included direct objective measurement of the width of the palpebral fissure after operation, grading of the severity of postoperative edema and ecchymosis from photographs, and observations by the patients regarding the clearing of the postoperative discoloration. It appeared from the results of these observations that Oxyphenbutazone is not effective in preventing postoperative edema in such operations or in promoting more rapid resolution of postoperative edema. It did appear to enhance the clearing of postoperative periorbital ecchymosis.     

INTRAVENOUS NUTRITION—A Clinical Evaluation of a 50 Per Cent Dextrose in Water Solution,Containing 1 mg. of Hydrocortisone per 100 ml

A 50 per cent dextrose in water solution, containing 1 mg. of hydrocortisone per 100 ml., was used successfully in 70 patients for intravenous nutritional maintenance and repletion. There were no adverse systemic effects during or following 216 infusions. The only undesirable local reaction was the rare occurrence of pain in the arm when the concentrated solutions were given too rapidly. Glycosuria was minimal if the infusion rate did not exceed 0.85 gm. of glucose per kilogram of body weight per hour, particularly if 50 units of insulin were added to each 550 ml. bottle of 50 per cent dextrose. In patients without significantly elevated serum potassium content, 30 mEq. of potassium chloride, acetate or phosphate was added to each bottle to prevent hypokalemia.Preliminary observations suggest that this new solution may be given safely intravenously, without need for cutdowns or plastic catheters, if the needle is carefully inserted and well immobilized in the arm vein and the duration of the infusion is not too prolonged. Further studies on the effect of such high caloric supplementation plus protein hydrolysates in parenteral nutritional repletion and maintenance are indicated.     

Ultraviolet Radiation Effects on Ehrlich Ascites Tumor Cells : Observations Using a Flying Spot Ultraviolet Microscope

A flying spot ultraviolet microscope, employing a fast scan and pulsed operation of the raster, has been used to induce radiation damage in ascites tumor slide cultures, and to study by time-lapse cinematography the progressive stages of cell damage. The cells observed came from a strain (EF₇) of the Ehrlich ascites carcinoma. Irradiated cells were found to show a characteristic syndrome of damage, involving blebbing at the cell surface, while control cells in the adjacent areas of the preparation remained unchanged. The end of the blebbing period is marked by swelling of the cells, and the time taken for this phenomenon to occur was used as a measure of the severity of the damage. It was found that the time required for swelling is dependent on the size of the dose employed, as well as on the sensitivity of the cells. This latter sensitivity was found to decline as the physiological age of the tumor increased. If ultraviolet illumination below 255 mµ is excluded, no symptoms of damage occur, even when very large doses are used. These observations are discussed in relation to the nature of the system in the cell which is affected.     

Limitations of Fibrinogen-Polymyxin Medium in Detecting Coagulase-Positive Staphylococci in Raw Milk

A fibrinogen-polymyxin medium and Staphylococcus Medium 110 were used in the isolation of coagulase-positive staphylococci in raw milk. Results indicated that both media allow the growth of some rods and of many coagulase-negative cocci. A significantly greater number of coagulase-positive staphylococci were identified by the tube test than were revealed by halo formation on fibrinogen-polymyxin medium.