A conserved genetic module that encodes the major virion components in both the coliphage T4 and the marine cyanophage S-PM2.

Sequence analysis of a 10-kb region of the genome of the marine cyanomyovirus S-PM2 reveals a homology to coliphage T4 that extends as a contiguous block from gene (g)18 to g23. The order of the S-PM2 genes in this region is similar to that of T4, but there are insertions and deletions of small ORFs of unknown function. In T4, g18 codes for the tail sheath, g19, the tail tube, g20, the head portal protein, g21, the prohead core protein, g22, a scaffolding protein, and g23, the major capsid protein. Thus, the entire module that determines the structural components of the phage head and contractile tail is conserved between T4 and this cyanophage. The significant differences in the morphology of these phages must reflect the considerable divergence of the amino acid sequence of their homologous virion proteins, which uniformly exceeds 50%. We suggest that their enormous diversity in the sea could be a result of genetic shuffling between disparate phages mediated by such commonly shared modules. These conserved sequences could facilitate genetic exchange by providing partially homologous substrates for recombination between otherwise divergent phage genomes. Such a mechanism would thus expand the pool of phage genes accessible by recombination to all those phages that share common modules.

A 10-year review of an industrial dermatitis clinic.

During a 10-year period, 678 patients were seen at an occupational dermatitis clinic attached to a District General Hospital. Of these, 424 were accepted as having an occupational dermatosis. The pattern of skin lesions and the patch test findings were those associated with a diversified light industrial setting coupled with a large traditional furniture industry. Fifty-one per cent of all cases were regarded as being allergic but the proportion varied greatly from one industry to another. Positive patch tests were obtained to the Standard European Series in 50.3% but additional tests increased this to 64%. In the furniture industry most of the positive reactions occurred only with such additional tests. The significance of the patch test reactions is discussed in relation to the findings in 992 unselected patients seen in the contact dermatitis clinic during a 3-year period.

Comparison of patch test results in two adjacent areas of England. II. Medicaments.

A 3-year study of patch test reactions to the Standard European Battery (S. E. B.) has been carried out in two adjacent areas of South-east England with the same climatic and cultural background. The source of materials and method of testing were identical; all observers have worked together in the same Contact Dermatitis Clinic and the interpretation of reactions can therefore be considered to be consistent. The main differences between the two areas lay in the pattern of employment and in local prescribing habits. Only the second aspect is considered here. Seven allergens--lanolin, neomycin, parabens, iodochlorhydroxyquinoline, ethylene diamine, caine 'mix' and chlorocresol--accounted for approximately 30% of all positive patch test reactions. 'Medicament sensitivity' correlated well with the known prescribing habits of both regions. Certain sites were shown to be especially important in the pathogenesis of medicament contact sensitivity.

[Some atypical forms of eczema in children (author's transl)]. / Sur quelques formes atypiques d'eczéma chez l'enfant.

Among 466 children under the age of 12 years who presented with eczema in a 5-year period, 68 p. 100 were atopic. 136 had various atypical signs of atopy. 44 suffered from pityriasis alba of sufficient intensity to justify referral for this reason; 10 had the typical features of seborrhoeic dermatitis of infants. 27 suffered from "forefoot" eczema ("juvenile plantar dermatosis"). The course and characteristics of this condition are discussed and compared with the series recently described in the West of Scotland. Our cases were exactly similar except for an aggravation in the summer months and the fact that our cases responded poorly to topical corticosteroids alone though improved with coal tar. Atopy and contact sensitivity to shoe materials are rare in both groups. We feel that this may be classified as "frictional" dermatitis and agree with our Scottish colleagues that the introduction of nylon socks during the last ten years may be important.