- Email: [email protected]
1415. Improving tests for chrome sensitivity
METHODS FOR ASSESSING TOXICITY,
735
1414. A refinement in phototoxicity testing Sams, W. M., Jr. (1966). The experimental production of drug phototoxicity in guinea pigs. II. Using artificial light sources. Archs Derm. 94, 773. A previous review (Cited in F.C.T. 1966, 4, 90) described the complexity of the mechanism of photosensitization by certain drugs and chemical agents, as a result of which difficulties have been encountered in the development of adequate tests for phototoxic potential in animals. A refinement in technique is now described. In testing guinea-pigs for photosensitization induced by chlorpromazine, demethylchlortetracycline and chiorothiazide, irradiation by fluorescent lamps, high-pressure mercury vapour lamps and a carbon-arc lamp was employed. The normal erythema effect produced on the animals' ears by irradiation alone tended to mask any true phototoxic reaction. Normal erythema could however be prevented or greatly decreased by interposing a transparent plastics sheet (Mylar) between the animal and the source. The time of irradiation was lower than was necessary when a glass screen was employed, and could be reduced to 8 hr with a fluorescent lamp or I-2 hr with a mercury lamp if a thin plastics sheet (0.00025 or 0.0005 ,~) was used in preference to a thicker one. Irradiation changes the transmission characteristics of the plastics sheet, which needs frequent replacement. Under a variety of conditions used, chlorpromazine consistently exhibited a positive effect but the other two drugs rarely induced a phototoxic response. 1415. Improving tests for chrome sensitivity Epstein, S. (1966). Detection of chromate sensitivity: Intradermal versus patch testing. Ann. Allergy 24, 68. Zelger, J. & Wachter, H. (1966). Ober die Beziehungen zwischen Chromat-und DichromatAllergic: Ein Beitrag zur Analyse der Chrom(Vl)-Allergie. Dermatologica "132, 45. We have already seen that a wide variation in the threshold for various salts of trivalent chromium (Cr m) is encountered during patch testing (Cited in F.C.T. 1967, 5, 433). The two papers now discussed deal with the application of potassium chromate (1) and dichromate (II) as test materials in patients with chrome sensitivity. Epstein (cited above) has studied the possibility that intradermal tests with weak solutions will reveal sensitivity in cases where patch tests are negative. He has found 0.1 ml of a 0.01 solution of II to be a reliable intradermal reagent. In patients sensitized to Cr this dose provoked a papular reaction exceeding 5 mm diameter and persisting for at least 48 hr. Such a test appears not to confer sensitization to Cr, though its use with other materials, particularly antibiotics, calls for some caution. Zelger & Wachter (cited above) have compared the sensitivity of the epicutaneous patch test when a solution of I buffered at pH I 1-7 and a solution of 1I buffered at pH 1.5 are used. In a series of 50 patients with Cr allergy tested with these two reagents, the threshold concentration of I1 required to provoke a reaction was 2-10 times higher than that of 1, in terms of the Cr content of the reagents. The difference is attributed to the alkaline reaction of the solution of I and its greater degree of ionization. 1416. A chemical test for tissue response to pulmonary irritants Dixon, J. R., Wagner, W. D., Martin, T. D., Keenan, R. G. & Stokinger, H. E. (1966). Metal shifts as early indicators of response from low-grade pulmonary irritation. Toxic. appl. Pharmac. 9, 225. In order to detect early tissue injury from pulmonary irritants, changes have been followed in the concentrations of metals and reduced glutathione (GSH) in the lungs and liver of rats following brief exposure to ozone (I). Rats were exposed to varying concentrations of I for 4 hr and the copper (Cu), zinc (Zn), molybdenum (Mo) and GSH contents of the lungs and liver were determined 3 and 20 hr
735
1414. A refinement in phototoxicity testing Sams, W. M., Jr. (1966). The experimental production of drug phototoxicity in guinea pigs. II. Using artificial light sources. Archs Derm. 94, 773. A previous review (Cited in F.C.T. 1966, 4, 90) described the complexity of the mechanism of photosensitization by certain drugs and chemical agents, as a result of which difficulties have been encountered in the development of adequate tests for phototoxic potential in animals. A refinement in technique is now described. In testing guinea-pigs for photosensitization induced by chlorpromazine, demethylchlortetracycline and chiorothiazide, irradiation by fluorescent lamps, high-pressure mercury vapour lamps and a carbon-arc lamp was employed. The normal erythema effect produced on the animals' ears by irradiation alone tended to mask any true phototoxic reaction. Normal erythema could however be prevented or greatly decreased by interposing a transparent plastics sheet (Mylar) between the animal and the source. The time of irradiation was lower than was necessary when a glass screen was employed, and could be reduced to 8 hr with a fluorescent lamp or I-2 hr with a mercury lamp if a thin plastics sheet (0.00025 or 0.0005 ,~) was used in preference to a thicker one. Irradiation changes the transmission characteristics of the plastics sheet, which needs frequent replacement. Under a variety of conditions used, chlorpromazine consistently exhibited a positive effect but the other two drugs rarely induced a phototoxic response. 1415. Improving tests for chrome sensitivity Epstein, S. (1966). Detection of chromate sensitivity: Intradermal versus patch testing. Ann. Allergy 24, 68. Zelger, J. & Wachter, H. (1966). Ober die Beziehungen zwischen Chromat-und DichromatAllergic: Ein Beitrag zur Analyse der Chrom(Vl)-Allergie. Dermatologica "132, 45. We have already seen that a wide variation in the threshold for various salts of trivalent chromium (Cr m) is encountered during patch testing (Cited in F.C.T. 1967, 5, 433). The two papers now discussed deal with the application of potassium chromate (1) and dichromate (II) as test materials in patients with chrome sensitivity. Epstein (cited above) has studied the possibility that intradermal tests with weak solutions will reveal sensitivity in cases where patch tests are negative. He has found 0.1 ml of a 0.01 solution of II to be a reliable intradermal reagent. In patients sensitized to Cr this dose provoked a papular reaction exceeding 5 mm diameter and persisting for at least 48 hr. Such a test appears not to confer sensitization to Cr, though its use with other materials, particularly antibiotics, calls for some caution. Zelger & Wachter (cited above) have compared the sensitivity of the epicutaneous patch test when a solution of I buffered at pH I 1-7 and a solution of 1I buffered at pH 1.5 are used. In a series of 50 patients with Cr allergy tested with these two reagents, the threshold concentration of I1 required to provoke a reaction was 2-10 times higher than that of 1, in terms of the Cr content of the reagents. The difference is attributed to the alkaline reaction of the solution of I and its greater degree of ionization. 1416. A chemical test for tissue response to pulmonary irritants Dixon, J. R., Wagner, W. D., Martin, T. D., Keenan, R. G. & Stokinger, H. E. (1966). Metal shifts as early indicators of response from low-grade pulmonary irritation. Toxic. appl. Pharmac. 9, 225. In order to detect early tissue injury from pulmonary irritants, changes have been followed in the concentrations of metals and reduced glutathione (GSH) in the lungs and liver of rats following brief exposure to ozone (I). Rats were exposed to varying concentrations of I for 4 hr and the copper (Cu), zinc (Zn), molybdenum (Mo) and GSH contents of the lungs and liver were determined 3 and 20 hr