Building-related symptoms are linked to the in vitro toxicity of indoor dust and airborne microbial propagules in schools: A cross-sectional study.

INTRODUCTION: Indoor microbial toxicity is suspected to cause some building-related symptoms, but supporting epidemiological data are lacking. OBJECTIVE: We examined whether the in vitro toxicity of indoor samples from school buildings was associated with work-related health symptoms (building-related symptoms, BRS). METHODS: Administrators of the Helsinki City Real Estate Department selected 15 schools for the study, and a questionnaire on symptoms connected to work was sent to the teachers in the selected schools for voluntary completion. The cellular toxicity of classroom samples was determined by testing substances extracted from wiped indoor dust and by testing microbial biomass that was cultured on fallout plates. Boar sperm cells were used as indicator cells, and motility loss was the indicator for toxic effects. The effects were expressed as the half maximal effective concentration (EC50) at which >50% of the exposed boar sperm cells were immobile compared to vehicle control. RESULTS: Completed symptom questionnaires were received from 232 teachers [median age, 43 years; 190 (82.3%) women] with a median time of 6 years working at their school. Samples from their classrooms were available and were assessed for cellular toxicity. The Poisson regression model showed that the impact of extracts of surface-wiped school classroom dust on teacher work-related BRS was 2.8-fold (95% CI: 1.6-4.9) higher in classrooms with a toxic threshold EC50 of 6µgml-1 versus classrooms with insignificant EC50 values (EC50 >50µgml-1); P<0.001. The number of symptoms that were alleviated during vacation was higher in school classrooms with high sperm toxicity compared to less toxic sites; the RR was 1.9 (95% CI: 1.1-3.3, P=0.03) for wiped dust extracts. CONCLUSIONS: Teachers working in classrooms where the samples showed high sperm toxicity had more BRS. The boar sperm cell motility inhibition assay appears promising as a tool for demonstrating the presence of indoor substances associated with BRS.

Computed tomography data based rapid prototyping model of the temporal bone before cochlear implant surgery.

Rapid prototyping (RP) technique allows automatic fabrication of 3D model parts. This method was applied to make a temporal bone model before cochlear implant surgery. A helical CT scan is used to acquire high resolution data from the middle and the inner ear of the patient. From the scanning data bone structures and soft tissues can be separated because their different grayscale pixel values. By using a guided image processing tool the desired parts of the anatomy can be extracted and 3D data created. The segmented data are processed to the form suitable for creating a high accuracy RP model. The RP model is made in the stereolithography (SLA) process by means of a computer guided HeCd laser beam inducing polymerisation of acrylic solution as it passes layer by layer over the surface of the polymer solution. In this prototype model the anatomy of the temporal bone can be clearly visualised, including, e.g., mastoid cells, tympanic cavity, bony canal of facial nerve, and round and oval windows. The inner ear spaces including vestibule, semicircular canals and cochlear turn are also shaped. The transparent acrylic material allows bonelike mechanical handling. The RP model can be dissected and used in individual surgical planning and simulation prior to cochlear implantation.

New speech-in-noise test in different types of hearing impairment.

A new test was developed to assess speech recognition in noise. The test was designed to be run in a personal computer supplied with a sound card. One thousand disyllabic test words and noise were stored in digitized form on the hard disk of the computer. The measure given by this test is speech recognition threshold in noise (SRTN) corresponding to 50% recognition. The present series of 180 cases with various hearing impairments and 39 controls were examined with speech-in-noise test and conventional audiometry. In keeping with earlier studies, the SRTN turned out to be significantly elevated in cases with sensorineural hearing impairment; this elevation was related to the grade of hearing impairment. On the other hand, no essential difference was seen between the SRTN values of subjects with mixed hearing impairment and persons with normal hearing.

Crucial questions for physiotherapy in Finland.

When planning for health services, questions of production and distribution as well as cost and quality are key issues for health planners and decision makers. The lack of available objective data often makes this work difficult. This paper presents recent efforts in Finland to improve the collection of information needed for planning in the field of physiotherapy.