Microscopic studies have been performed on skin biopsies from five patients with occupational argyria. Small brown-black granules were present in the dermis on light microscopy and were intensely refractile with dark-field illumination. Electron microscopy showed that the granules were electron-dense, round or oval in shape and varied in size from 30 nm to 100 nm. They were most numerous in relation to the basal lamina of the eccrine sweat glands, but were also present in relation to the basal lamina of the epidermis and dermal elastic fibres. X-ray microanalysis confirmed that many of the granules contained silver and sulphur. However, selenium, mercury, titanium and iron were also identified and it is probable that these elements were deposited in the skin also as a result of occupational exposure.

Three children are described in whom painful subcutaneous nodules developed 1-2 years after the injection of adsorbed diphtheria, tetanus and pertussis vaccine. The diagnosis of aluminium hydroxide granuloma was established by ultrastructural examination with X-ray microanalysis.Mild cutaneous reactions frequently occur with adsorbed diphtheria, tetanus and pertussis (DTP) vaccines (Burland et al, 1968). Persistent nodules are seen less commonly, but previous histological studies have suggested a localized response to retained aluminium hydroxide (Erdohazi & Newman, 1971;Savage, 1973)-We describe three cases of aluminium hydroxide granulomas where the diagnosis was established by ultrastructural examination with X-ray microanalysis. These findings do not appear to have been previously reported. PATIENTS Case IAn 18-month-old boy was referred to a surgeon with several small painful subcutaneous nodules (1-5 mm diameter) over the left deltoid muscle. The nodules had developed over the preceding months following the injection of adsorbed DTP vaccine 13 and 15 months previously. The nodules were excised under general anaesthesia but not submitted for histology. However, a new nodule appeared 3 months later and following removal was submitted for histology. Case 2A 2-year-old girl was referred to a surgeon with a i-month history of a 5-mm diameter painful

We report on an extensive investigation of photodarkening in Yb-doped silica fibers. A set of similar fibers, covering a large Yb concentration range, was made so as to compare the photodarkening induced losses. Careful measurements were made to ensure equal and uniform inversion for all the tested fibers. The results show that, with the specific set-up, the stretching parameter obtained through fitting has a very limited variation. This gives more meaning to the fitting parameters. Results tend to indicate a square law dependence of the concentration of excited ions on the final saturated loss. We also demonstrate self-similarity of loss evolution when experimental curves are simply normalized to fitting parameters. This evidence of self-similarity also supports the possibility of introducing a preliminary figure of merit for Yb-doped fiber. This will allow the impact of photodarkening on laser/amplifier devices to be evaluated.

No abstract