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Biomedical subjects

J Niskanen

Publications and source records attributed to J Niskanen.

14 recordsLinked to original sources
PubMed2001

Ways to promote a noise control programme.

The purpose of this study was to find out the proper ways to promote and to start a noise control programme in small and medium size industries. The situation of the noise control programme was inspected in four industrial enterprises. The noise exposure and the noise sources were studied and recommendations for noise reduction were given. The information concerning the noise control programme and noise levels was given to the personnel. How the noise control programme was started in the companies and which were the best ways to promote the programme were examined after 1 year. Noise reduction work was carried out in companies during the past year and new ideas were awaiting investment. The systematic noise control programme was not written on paper or connected to a risk management programme. The lack of proper models of a programme, lack of time and knowledge of easy means to reduce the noise were reasons for missing noise control programmes. The best ways to push up the noise control programme were to give information and examples of the programme. The EU-directive concerning machines and its noise information was a help in the noise reduction work connected with new investments.

Health Promotion↗
PubMed1999

[An odd ECG].

Explore the source record for details and available documents.

Arrhythmias, Cardiac↗
PubMed1995

Cutaneous heat loss in children during anaesthesia.

We have measured non-evaporative, cutaneous heat loss using heat flux transducers at eight skin sites in five children during anaesthesia and compared the data with basal metabolic heat production. The effect of disposable surgical covering and a radiant heater on heat flux was examined. The mean total heat flow rate before draping was 3-9 W higher than the basal metabolic rate after induction of anaesthesia with a simultaneous decrease in rectal temperature. Mean cutaneous heat loss was 62 (SD 9) W m-2 (9.5 (2.1) kJ kg-1 h-1) in children older than 1 yr and 84 W m-2 (17.2 kJ kg-1 h-1) in a 3-month-old infant. Disposable drapes diminished cutaneous heat loss by 29% and a radian heater by 77%. Heat conduction to the mattress was 21 (7) W m-2. These results showed that the decrease in core temperature after induction of anaesthesia was genuine cooling, that is heat loss exceeded heat production.

Anesthesia, General↗
PubMed1995

Prevention of the adverse health effects of cold by using infrared heaters.

The aim of the work has been to develop a planning guide for local infrared heating systems and to compare the results to the heaters in the work place. The planning process for radiators is started by defining the goal ambient temperature and then the electric power needed for the radiators. The planning result should always be compared to the recommendations for infrared radiation. The usefulness of the planning instructions were tested by building a local heater for a cooled storage where a computer was used. The increase in operative temperature and the physiological responses of workers were measured as well as the change in the thermal sensations after using heaters. With these heaters the operative temperature increases 7 degrees C. The skin temperature of the fingers increased about 7 degrees C, which is meaningful, when finger dexterity is needed in using computers. Also the thermal sensations increased all over the body. Both the planning instructions developed and the local heating system turned out to be very useful. Also the low costs of local heaters are a good reason for using them. However the exact direction and the narrow bean cone of the heaters are important in obtain the maximum benefit from them.

Body Temperature↗
PubMed1995

Vibration syndrome in railway track maintenance workers.

An inquiry was sent to all railway maintenance workers in three railway districts in Finland and hand-arm vibration was measured on the handlebars of tools used by maintenance workers. The study group included 252 (82%) subjects, whose mean age was 41 years and who had worked in track maintenance for 14 years (SD 9). In Finland there are over 600 railway maintenance workers who use vibrating tools. The frequency-weighted acceleration of hand-arm vibration was calculated according to the ISO 5349 standard. Hand-held tamping machines had caused most of the vibration exposure, and aw4h was 10.6 m/s2 measured on the handlebar of tamping machine, but many workers also used other vibrating tools. The annual vibration level was 2.5 m/s2 when the use of all vibrating tools and the exposure time was taken into account. In the questionnaire the prevalence of vibration-induced white finger (VWF) was 14% in the entire material, and the prevalence of VWF increased significantly with the total duration of the maintenance work. In addition, 39% of the subjects had suffered numbness of the hands, and the prevalence of hand numbness also increased significantly with the total duration of maintenance work. According to the measurements of vibration and the prevalence of hand symptoms the present investigation indicates vibration syndrome as being related to railway track maintenance work. In the exposure group, where tamping machines mainly were used and exposure to other vibration was small, the prevalence of VWF was also significantly higher, but the prevalence of hand numbness insignificant compared with the control group. In this study vascular and nerve hand symptoms were considered to cause serious trouble in work by 4-11% of the maintenance workers.

Adult↗
PubMed1995

Hand-arm vibration and terrain vehicles.

Hand-arm vibration was measured on the handlebars of terrain vehicles (N = 36) and a postal inquiry was made among N = 2705 reindeer herders (snowmobile drivers). Since many subjects had also used other vibrating tools the snowmobile group proper (N = 334) was established. In the whole group 19% of the subjects reported having experienced white finger attacks and 48% numbness of the hands. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation using the ISO 5349 standard predicted the prevalence of white finger well in the snowmobile group proper. The vibration levels were 1.6-7.9 m/s2 on snowmobiles, 5.5-11.8 m/s2 on all-terrain vehicles and 6.9-12.7 m/s2 on terrain motorcycles. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is need for health care, technical improvements, and other protection means to reduce the symptoms of vibration in driving terrain vehicles.

Adult↗
PubMed1994

Calculation of mean skin temperature and changes in body heat content during paediatric anaesthesia.

Mean skin temperature and changes in body heat content were calculated in several different ways from measurements made in five children during operation. Mean skin temperatures were calculated from 162 sets of measurements using 15, 12, eight, seven and four skin sites with various formulae modified according to age. The results of other formulae were compared with age-adjusted, area-weighted 15-site mean skin temperature which was used as a reference. Changes in body heat content were calculated from Burton's equation in different ways and errors from different variables in the formula were evaluated. Mean skin temperature from 12 skin sites was within 0.5 degrees C of the 15-point reference method, and that from four sites within 1 degree C. The core temperature selected and the weighting coefficients used in calculating mean body temperature were more important sources of error in the determination of change in body heat content than was mean skin temperature.

Anesthesia, General↗
PubMed1994

Whole body vibration and the snowmobile.

The whole body vibration from the seat and foot board was measured during ten years from 11 different snowmobiles to evaluate the exposure and the need for technical improvements. In a questionnaire more than half of the drivers had back pains but only a few of them considered the whole body vibration as a health hazard. However in the literature there is often comments on spinal injuries related to shock vibration. The frequency-weighted acceleration of snowmobile vibration was from 1 to 6.1 m/s2 and the risk evaluation using the ISO standard predicted the problems. Speed and the unevenness of the driving terrain caused vibration. The damping depends on the properties of the seat, terrain and speed limits. Also the driving posture is important. Especially on the snowmobile tracks the whole body vibration was high and according to modern knowledge more attention should be paid the technical properties of snowmobiles.

Humans↗
PubMed1994

Service of snowmobiles in the wilderness and villages.

The maintenance of terrain vehicles like snowmobiles has been developed for arctic wilderness use by paying attention to occupational health, safety and quality and efficiency of work. A small tent carried on a snowmobile sledge supplied with heating and lighting equipment was planned, built and tested. It was sized based on an ergonomic survey for the servicing of snowmobiles. The planned thermal and occupational aims were reached at temperatures down to -35 degrees C. Two movable, shielded fluorescent lamps with total of 140 W electric power was enough to produce 150 lx illumination and the local illumination for the repair point was 700 lx. The 8 kW warm air fan had enough power to hold the temperature inside at the desired level with an outside temperature of -35 degrees C. The fan was also used as a local heater by conducting warm air to the hands and tools. The temperature of the fingers was close to the comfort level, when repair work was carried in the tent. When the repair work was carried out outside, the finger temperature was near the risk of cold injury. The handles of the tools were made from heat insulating materials, which raised the contact skin temperature with about 3 degrees C.

Cold Temperature↗
PubMed1994

Developing the snowmobile helmet.

With the annually increasing use of snowmobiles in the Nordic countries the amount of accidents is also increasing. The head is the location of some of the most serious injuries with head injuries comprising 12% of all injuries. At the time being there is no special standard for the snowmobile helmet and there are mainly two kinds of helmet models on the market: full face and open face helmets. The most significant differences between the helmets were observed in the subjective evaluation, whereas the differences were minimal in technical evaluation. According to this study an open face helmet was more comfortable than a full face helmet. The present helmets have many deficiencies such as the lack of thermal comfort, high weight, slow removal of mist from the visor and unsatisfactory hearing protection. The aim of future development projects should be to make a more comfortable and lighter helmet. One important aspect of the project could be to integrate hearing protectors and an information channel in the helmet.

Craniocerebral Trauma↗
PubMed1990

Site-directed mutagenesis of a thermostable alpha-amylase from Bacillus stearothermophilus: putative role of three conserved residues.

The relationship between structure, activity, and stability of the thermostable Bacillus stearothermophilus alpha-amylase was studied by site-directed mutagenesis of the three most conserved residues. Mutation of His-238 to Asp involved in Ca2+ and substrate binding reduced the specific activity and thermal stability, but did not affect the pH and temperature optima. Replacement of Asp-331 by Glu in the active site caused almost total inactivation. Interestingly, in prolonged incubation this mutant enzyme showed an altered end-product profile by liberating only maltose and maltotriose. Conservative mutation of the conserved Arg-232 by Lys, for which no function has yet been proposed, resulted in lowered specific activity: around 12% of the parental enzyme. This mutant enzyme had a wider pH range but about the same temperature optimum and thermal stability as the wild-type enzyme. Results obtained with different mutants were interpreted by computer aided molecular modeling.

Amino Acid Sequence↗
PubMed1985

Effects of high dose progestin on serum lipids and lipid metabolizing enzymes in patients with endometrial cancer.

The effect of high dose medroxyprogesterone acetate (MPA) on serum lipids, on adipose tissue lipoprotein lipase (LPL) and serum lecithin cholesterol acyltransferase activities were studied in 15 postmenopausal patients with endometrial cancer. After 2 weeks of MPA treatment total cholesterol decreased by 14% (P less than 0.001) and HDL cholesterol by 33% (P less than 0.01) from the respective pretreatment values; correspondingly the ratio of HDL to total cholesterol decreased (P less than 0.05). The decrease of HDL2 cholesterol was 35% (P less than 0.01) and that of HDL3 cholesterol 15% (P less than 0.01). The levels of serum triglycerides decreased significantly (P less than 0.05) during the treatment period. Serum LCAT activity was significantly lower (P less than 0.05) after treatment than before, but adipose tissue LPL activity was not altered. The mean serum testosterone level decreased significantly (P less than 0.001) from the pretreatment values. Significant positive correlations were present between LPL activity and MPA concentrations and between LPL activity and testosterone concentrations after the drug treatment.

Adipose Tissue↗
PubMed1982

Effect of pindolol on serum lipids and lipid metabolizing enzymes.

1 The effect on plasma lipids of pindolol given orally over a 6 month period to 20 patients with essential hypertension was studied. 2 During therapy an adipose tissue biopsy was taken from nine patients for the determination of lipoprotein lipase (LPL) activity and serum samples were taken for lecithin cholesterol acyltransferase (LCAT) assays. An additional biopsy and serum samples were taken after a 3 weeks' break in pindolol treatment. 3 Plasma free fatty acid and triglyceride concentrations remained similar during treatment. 4 Plasma total cholesterol was slightly lower (P less than 0.05) at 6 months than at 1 month. 5 HDL cholesterol concentration and the ratio of HDL to total cholesterol increased slightly, and the increase of HDL-cholesterol was significant (P less than 0.05) at 1 month. 6 LCAT activity was significantly higher (P less than 0.01) during pindolol treatment than after the break in it. No significant changes in adipose tissue LPL activities were found before and after the break of treatment.

Adipose Tissue↗