Contact dermatitis to polyester spin finishes
A female laboratory assistant, aged 28, showed yellow stained palms and nails when examined for paronychia of two fingers. Determination of amylase involved contact with dinitro salicylic acid (DNSA) in several steps. It was found that plastic gloves used in dishwashing the utensils were rapidly penetrated by DNSA. Though she did not work with DNSA for 4 months, the yellow stains did not disappear. Yellow stains were now also observed on her cheeks and soles. For about 2 months she had been taking a drug containing Nitrazepam, 5phenyl-7-nitro-lH -1.4-benzodiazepin-2(3H)-on. She stopped using Nitrazepam and the yellow staining decreased, but when she again beg~n to have contact with DNSA in her work, the yellow stains had not disappeared completely. They increased again on palms and nails but not on cheeks or soles. She then moved to another place and it has not been possible to examine her again. It is obvious that the patient's skin was first stained yellow by DNSA. It can only be suspected but not established with certainty that Nitrazepam gave yellow stains on her cheeks and soles. We did not find reports on yellow staining from Nitrazepam, nor does the manufacturer have any such reports on file. It is known that aromatic nitro compounds stain skin, nails and hair yellow. Thus explosives, e.g. trinitrotoluene, give such staining. Some of the aromatic nitro compounds are yellow and can then stain by simple contamination. However, there is staining by chemical reaction, but the nature of this reaction seems to be only partly studied. Aromatic nitro compounds might combine with amino acids in three ways: The phenols act as weak acids and form salts with aminogroups in basic amino acids, e.g. histidine, lysine and argmme. DNSA acts in the same way. Aromatic nitro compounds may form charge transfer complexes with aromatic rings. Some amino acids, e.g. tryptophane, tyrosine and phenylalanine contain such rings. When the aromatic nitro compounds contain, for example, a halogen or a sulfonyl group, they may form covalent linkages with amino acids. Many of the aromatic nitro compounds are yellowish and the compounds formed may therefore become stained. Particularly the covalent linkage can change the color and strong yellow staining may arise from weak or uncolored aromatic nitro compounds.
Contact Allergenicity of Methylene-bis(thiocyanate) in the Guinea Pig Maximization Test
Methylene-bis(thiocyanate) (MBTC), an antimicrobial agent used in water-cooling systems, soluble cutting oils, and paper mills, was evaluated for its skin sensitization potency in both the induction and elicitation phases in a modified guinea pig maximization test (GPMT). MBTC showed strong sensitization potential in GPMT, so that a topical application using a patch with a relatively high concentration of MBTC (10,000 ppm) was able to sensitize 100% of guinea pigs alone, without an intradermal injection. At a dose of 5 ppm in both the intradermal injection and the topical application, the compound produced skin sensitization in 60% of animals. The strongest positive skin reaction was elicited not in the group of animals sensitized with 5,000 ppm MBTC, the highest induction dose tested, but in the group treated with 500 ppm MBTC. The lowest elicitation concentration was 50 ppm in groups sensitized with 50 or 500 ppm MBTC. MBTC-sensitized animals cross-reacted to benzyl thiocyanate, chloromethyl thiocyanate, and 2-(thiocyanomethylthio) benzothiazole, but not to calcium thiocyanate, methyl isothiocyanate, or methylene dicyanide. The data showed that the presence of a thiocyanomethyl group in the chemical structure of a compound is essential for cross-reactivity in MBTC-sensitized animals.
Synthesis of 2,4-dideoxy-.beta.-D-erythro-hexopyranosyl nucleosides
The synthesis of 1-(2,4-dideoxy-β-D-erythro-hexopyranosyl)thymine (12) 1 was accomplished using two different synthetic routes. It was obtained starting either from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose or from tri-O-acetyl-D-glucal. The other modified nucleosides, with either a cytosine, guanine, or adenine moiety, were synthesized using the second reaction scheme. Deoxygenation reactions were accomplished with the (2,4-dichlorophenoxy)thiocarbonyl derivatives generated in situ