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Biomedical subjects

A Axelsson

Publications and source records attributed to A Axelsson.

At least 73 records · Page 4Linked to original sources
PubMed1992

Noise levels from toys and recreational articles for children and teenagers.

This study examined the noise level emitted by toys and recreational articles used by children and teenagers. The results indicate that many of the items tested emit sufficiently intense noise to be a source of noise induced hearing loss in school-age children. While the baby toys provided noise exposure within the limits of national regulations, they are most intense in a frequency range that corresponds to the resonance frequency of the external auditory canal of very young children. Hobby motors emit noise that may require protection depending upon the length of use. Fire-crackers and cap guns emit impulse noises that exceed even conservative standards for noise exposure.

Adolescent↗
PubMed1991

Simulation of batch and continuous reactors with co-immobilized yeast and beta-galactosidase.

A reaction-diffusion model was used to simulate a co-immobilized system utilizing the numerical method of orthogonal collocation. The production of ethanol from deproteinized whey using beta-galactosidase co-immobilized with Saccharomyces cerevisiae in calcium alginate gel beads was chosen as a model system. Calculated concentrations of lactose, glucose, galactose and ethanol were compared with experimental data for a batch reactor and a continuous horizontal packed-bed reactor. The mathematical model has been used to analyse the influence of internal and external mass transfer for the continuous reactor. The external mass transfer was shown to be of minor importance. The introduction of baffles decreased the backmixing in the horizontal packed-bed reactor. Internal mass transfer was found to be the main cause of the reduction in the apparent reaction rate. Thus, much of the expected increase in reaction rate is diminished by mass transfer hindrance when the cell concentration is increased.

Alginates↗
PubMed1991

Inner ear damage from toy cap pistols and fire-crackers.

Groups of guinea pigs comprising 7 animals in each group were exposed to 10, 50 or 100 exposures to fire-crackers or 10, 50 or 100 exposures to toy cap pistol shots. An additional group of 7 animals comprised the control material. The exposures were performed with 15-s intervals at 0.25 m distance for the toy cap pistol shots and at 0.8 m for the fire-crackers. The peak sound level at the ear was 155 dBC for both impulsive sounds. After a 3-week survival period the animals were anesthetized and decapitated. The cochleas were examined histologically in surface preparations and read double-blind. One animal in each group exposed to 10 fire-crackers and 10 toy cap pistol shots showed sensory cell loss. With 50 or 100 toy cap pistol shots or fire-cracker exposures, 24 out of 28 animals showed pronounced sensory cell loss. The present results clearly indicate the risk for noise-induced hearing loss in children playing with toy cap guns and fire-crackers.

Animals↗
PubMed1991

Psychological dimensions in patients with disabling tinnitus and craniomandibular disorders.

Forty-two patients with severe tinnitus and craniomandibular disorders (CMD) are presented from an audiological and psychological point of view. During a 2-week period, the patients rated their mood and their tinnitus. Based upon mood ratings, patients were grouped into three clusters (high, medium and low mood). The three groups differed in a number of respects, audiological as well as psychological. Patients in the low mood group experienced significantly more intense and severe tinnitus and more daily stress than patients in the high mood group. Ratings of irritation and concentration difficulties seemed to be mood related, and discriminated between patients in the low mood group and patients in the moderate and the high mood groups. Difference in hearing level between the left and the right ear was more pronounced in patients with low mood. There were, however, no significant differences between the groups in the stomatognathic variables. It is concluded that the above mentioned audiological and psychological observations should be considered as potentially important for satisfactory management of individual tinnitus patients. Further studies of the effects of optimally compensated hearing on depressed mood in patients with noise-induced hearing loss (NIHL) and tinnitus are required.

Affect↗
PubMed1990

Prevalence of signs and symptoms of craniomandibular disorders in tinnitus patients.

One hundred two tinnitus patients were examined to determine the prevalence of signs and symptoms of CMD. The examination comprised determination of the anamnestic and clinical dysfunction indices according to Helkimo; assessment of the dentition, occlusal factors, and signs of parafunctions; and accomplishment of a tension test. Patients also answered a questionnaire concerning the presence and frequency of CMD symptoms and headaches, as well as influence on tinnitus by mandibular movements, by pressure applied to the TMJ, or by dental therapy. Frequent headaches and fatigue/tenderness in jaw muscles were more prevalent in tinnitus patients than in epidemiologic samples, as was the prevalence of clinical findings of pain on palpation of masticatory muscles, impaired mandibular mobility, and signs of parafunctions. About one-third of the patients reported influence on tinnitus by mandibular movements and/or pressure applied to the TMJs. A theoretic model of causal connections between tinnitus and signs and symptoms of CMD in some tinnitus patients is suggested.

Adolescent↗
PubMed1989

Noise and vibration interactions: effects on hearing.

There is the suggestion in the literature that vibration may potentiate the effects of noise and may thus increase the risk of hearing loss in a variety of exposure situations. However, in human experimental studies, which, by necessity, are limited to low levels of exposure, the effects measured are relatively small. A very limited number of animal studies have also shown an enhanced noise-induced hearing loss in the presence of vibration, but the scope of these studies is limited. The animal studies (chinchilla) that form the basis of this report were performed using a 30-Hz, 3g rms and a 20-Hz, 1.3g rms cage vibration separately and in combination with continuous noise (95-dB, 0.5-kHz octave band) and impact noise (113, 119, or 125 dB peak SPL) exposure paradigms. All exposures lasted for 5 days. The impact noise exposures were designed to have approximately equal total energy. Temporary and permanent threshold shifts were measured using evoked potentials, and sensory cell loss was measured using surface preparation histology. The results obtained from some of the noise/vibration paradigms showed that such exposures can alter some of the dependent measures of hearing. This effect was statistically significant only for the stronger vibration exposure conditions and was evident primarily in the extent of the outer hair cell losses and in the shape of the PTS audiogram.

Animals↗
PubMed1989

The influence of carbogen on susceptibility to TTS.

A group of 20 male subjects were exposed to noise in each of four separate conditions. In two conditions they inhaled carbogen (95% oxygen, 5% carbon-dioxide). In two others they inhaled compressed air. In two conditions they were exposed to noise after inhalation and in two they were exposed to noise during the inhalation. The results indicated that carbogen inhalation reduced the magnitude of TTS but only in the 'During' condition.

Adolescent↗
PubMed1989

Tinnitus--a study of its prevalence and characteristics.

Three thousand six hundred randomly selected adults in the city of Gothenburg (425,000 inhabitants) stratified by age and gender, were questioned by mail concerning tinnitus. We received 66% useful answers, 14.2% suffered from tinnitus 'often' or 'always'. Tinnitus was more common in males than in females. Tinnitus was much more common in the left than in the right ear. 2.4% of the whole population suffered from the worst severity degree, 'tinnitus plagues me all day'. Tinnitus was clearly more common with hearing loss than with subjectively normal hearing. Sleep disturbances were common and increased with tinnitus severity. A majority of the questioned subjects wanted further examination and treatment.

Adult↗
PubMed1988

The influence of physical exercise on susceptibility to noise-induced temporary threshold shift.

In order to investigate whether physical exercise would influence susceptibility to temporary threshold shift (TTS), 9 subjects were exposed to a narrow-band noise at 105 dB SPL for 10 min three times in each of four test conditions. In three of the test conditions, noise exposure was combined with physical exercise at a level of 40% of the individual subject's maximum work capacity. Under these conditions, subjects were exposed to the noise before, during, or after exercise. In the fourth condition, subjects were exposed to the noise only. The results indicated that noise with simultaneous exercise increased the TTS susceptibility when compared with the other test conditions (p less than or equal to 0.05).

Adult↗
PubMed1988

Acute acoustic trauma. An emergency condition.

This paper reviews 16 selected patients reporting for acute acoustic trauma (AAT). All patients had a fairly recent pre-accident audiogram. Most of the patients were tested audiologically immediately after the acoustic accident. All patients were men, with ages varying between 16 and 50 years. Eight patients received pharmacological treatment with low-molecular-dextran intravenously, papaverin perorally and prednisolone perorally. The high-frequency pure-tone average (3-4-6 kHz) was more affected than the pure-tone average (0.5-1-2 kHz). In 2 patients, the converse was true. The most affected frequencies were 3, 4, and 6 kHz. The initial maximum hearing loss varied between 15 and 70 dB. In 6 patients, extra-high-frequency audiometry (8-20 kHz) was performed and in all patients an asymmetry was demonstrated. Younger patients had somewhat more hearing improvement after AAT than older patients. It also appears that patients reporting early had a somewhat better healing course than patients reporting later.

Accidents↗
PubMed1988

Hearing loss at age 7, 10 and 13--an audiometric follow-up study.

School children are regularly tested in Sweden at age 7, 10 and 13. We report the audiometric results of 2264 school children tested at these three ages. Audiometry was performed as hearing screening at 0.5, 1, 2, 4, 6, 8 kHz with a screening level of 20 dBHL. Unilateral hearing losses with one test frequency affected were most common and bilateral hearing losses were least common. The hearing loss was more common in boys than in girls at all ages. Hearing loss at 2 kHz in boys at age 7 were uncharged in most cases (13/17 boys still failing screening at age 13). High frequency losses were most common, particularly at age 10 and 13 and more prevalent in boys than in girls, suggesting early noise induced hearing loss as an etiology.

Adolescent↗
PubMed1987

The effects of noise on histological measures of the cochlear vasculature and red blood cells: a review.

This paper compiles the results from seven experiments which have investigated noise exposure effects on histological measures of the cochlear vasculature and red blood cells. Two of these studies included at least two experimental conditions and all evaluated numerous histological parameters in several cochlear vessels. The combined results suggest that noise has a consistent general effect of reducing apparent cochlear blood flow as indicated by decreased RBC density, increased aggregation of RBCs, increased variability in RBC density, decreased number of RBC columns, increased vessel lumen irregularity and encroachment of perivascular cells upon the lumen wall. When considered at the level of the individual vessels, however, inconsistent results were observed. Fewer effects were noted in experiments which permitted animals to survive after the noise exposure than in those which sacrificed the animals immediately. Impulse noise resulted in more frequent vascular sequelae than did continuous noise. Further, impulse noise more frequently influenced vessels of the external wall than did continuous noise.

Animals↗
PubMed1987

The effects of smoking and physical exercise on temporary threshold shifts.

The Temporary Threshold Shifts (TTS) of 9 habitual smokers and 9 non-smokers were determined twice (via Békésy sweep procedures) after each of three conditions: 10 min of physical exercise, 10 min of 105 dB SPL exposure to a third octave band noise centered around 2 kHz, and 10 min of both exercise and noise. Smokers evidenced less TTS than did non-smokers, particularly when exposed to both noise and exercise and especially in the range of 2.5 to 5 kHz. Heart rate and systolic blood pressure increased more for smokers than for non-smokers, particularly when they were required to exercise. Oral temperature was positively correlated with the magnitude of TTS.

Adolescent↗
PubMed1987

Hearing loss in school children. A longitudinal study of sensorineural hearing impairment.

In a longitudinal study, 2325 children were hearing tested at age 7, 10 and 13 with screening audiometry. The screening level was 20 dB HL. Approximately 75% of the children passed the screening level at all ages. Hearing loss was more frequent in boys than in girls at age 13 (16%:9%). The left ear was more commonly affected than the right ear. High frequency dips increased for boys with age, but not for girls. The increasing incidence of hearing loss for boys with age is probably due to noisy leisure time activities.

Adolescent↗
PubMed1986

Comparison of tympanometry and otomicroscopy during healing of otitis media.

One hundred ears in 50 children with acute otitis media during healing were examined with tympanometry and the objective measures were compared with the subjective evaluation of otomicroscopy by four otolaryngologists independently. Tympanometric findings could more often correctly suggest reduced tympanic membrane mobility than did otomicroscopy, but both methods gave an equally good indication of middle ear effusion. However, otomicroscopy was necessary when evaluating the colour and the appearance of the tympanic membrane and revealed middle ear effusion in a few cases with 'normal' tympanometry. As a rule: normal tympanometry (Jerger type A) was closely correlated with a normal tympanic membrane and a normal middle ear without effusion; pathological tympanometry (Jerger type B) was accompanied by middle ear effusion and needed follow-up; ears with tympanometric pressure more negative than -150 mmH2O but more positive than a flat curve needed otomicroscopy to identify middle ear effusion.

Acoustic Impedance Tests↗
PubMed1986

Temporary threshold shift induced by noise exposure and moderate salicylate intake.

Temporary threshold shift was examined in 10 voluntary subjects who were exposed on 5 occasions to noise only and on 5 additional occasions to noise after intake of 1 g acetylsalicylic acid (ASA). The results showed no evidence that moderate doses of ASA potentiate temporary threshold shift. Subjects tested before and 1 hour after intake of ASA showed hearing improvement after intake of ASA. This threshold shift was confirmed, by a control trial, to depend on a practice effect rather than on the ASA.

Adolescent↗