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Usher syndrome is a recessive hereditary disease group with clinical and genetical heterogeneity leading to handicapped hearing and visual loss until middle age. It is the most common cause for deaf-blindness. Three distinct phenotypes and five distinct genotypes are already known. In Finland the distribution of known Usher types is different than elsewhere. Usher syndrome type III (USH3) is common in Finland and it is thought to include 40% of patients. Progressive hearing loss is characteristic of USH3. Elsewhere USH3 has been regarded as a rarity covering only several percent of the whole Usher population. The aim of this paper is to describe, for the first time, the course of visual handicap and typical refractive errors in USH3 and compare it with other USH types. From a total patient sample consisting of 229 Finnish USH patients, 200 patients' visual findings were analyzed in a multicenter retrospective follow-up study. The average progress rate during a 10-year follow-up period in different USH types was similar. The essential progress occurred below the age of 40 and was continuous up to that age. Visual acuity dropped below 0.05 (severely impaired) at the age of 37 and the visual fields were of tubular shape without any peripheric islands at the average age of 30. Clinically significant hypermetropia with astigmatism seems to be a pathognomonic clinical sign of USH3.

Emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) from municipal waste incineration are currently a subject of considerable public concern because of their extreme toxicity. PCDD/F formation in incineration processes is being studied widely, but studies on inhibition are quite sparse, especially in a pilot-plant scale. In this work, the effect of four gaseous inhibitors (sulfur dioxide, ammonia, dimethylamine, and methyl mercaptan) on PCDD/PCDF formation in the combustion of liquid fuel was studied using a pilot-scale plant. The inhibitors were injected into the flue gas stream after the first economizer at a temperature of 670 °C and just before the second economizer at 410 °C. Both the chlorophenol and PCDD and PCDF concentrations decreased when inhibitors were added. Particle-phase PCDD/F concentrations in particular decreased by up to 98%. The results suggest that the formation of PCDD/Fs is hindered in the particle phase at the early stages of the PCDD/F formation chain, probably even before precursors such as chlorophenols have been formed.