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Biomedical subjects

B Engström

Publications and source records attributed to B Engström.

At least 55 records · Page 3Linked to original sources
PubMed1990

Hearing and cochlear morphology in patients treated with a combination of cytostatics.

Patients with small-cell carcinoma of the lung were treated at the Department of Lung Medicine. They all received the same combination treatment with repeated doses of doxorubicin, vincristine, cyclophosphamide and methotrexate. In 26 patients, hearing was tested with repeated audiograms during treatment. The follow-up time varied between one and 19 months (mean, 6 months). There was no significant impairment of hearing during the follow-up period. Postmortem fixation of the temporal bones was performed in 7 patients and the cochlear morphology studied. No specific alterations in cochlear morphology which could be attributed to the cytostatics were found.

Adult↗
PubMed1989

The combined effect of cisplatin and furosemide on hearing function in guinea pigs.

The effect of the combined administration of cisplatin and furosemide on the electrophysiological hearing thresholds and endocochlear DC potential (EP) was studied in guinea pigs. A lack of interaction was found in animals given repeated intraperitoneal injections of a low dose of cisplatin with a pharmacological dose of furosemide. An ototoxic interaction occurred when a moderately high dose of cisplatin was administered intravenously at a time when the strial function was most affected by a very high dose of furosemide. The interaction was seen both as a decreased EP and a pronounced shift of auditory thresholds. It is concluded that the stria vascularis plays a role in the ototoxic mechanism of cisplatin.

Animals↗
PubMed1989

The ototoxic effect of cisplatin on guinea pigs in relation to dosage.

The effect on the electrophysiological hearing thresholds and the endocochlear DC potential (EP) was studied in four groups of guinea pigs receiving different doses of cisplatin. By multiple low-dose intraperitoneal injections a permanent hearing loss was produced without a permanent decrease of the EP. On the other hand, when cisplatin was given as a single high-dose intravenous injection, there was an impairment of the electrophysiological hearing thresholds and EP, depending upon the level of cisplatin dose. It is concluded that cisplatin-induced hearing loss is not necessarily a sequela to a loss of EP.

Animals↗
PubMed1989

Noise level, inner hair cell damage, audiometric features, and equal-energy hypothesis.

Rabbits were exposed to 2- to 7-kHz noise either for a short duration at a high sound-pressure level (15 or 30 min at 115 dB SPL), or a long duration at a low level (512 h at 85 dB SPL). The high-level exposure produced a hearing loss in the frequency range 2-6 kHz, whereas the low-level exposure gave maximum hearing loss at 12-20 kHz. The 115-dB exposure caused significantly more damage to inner hair cells than the 85-dB exposure. The implications of the present results for evaluating audiograms, equal-energy hypothesis, risk criteria, and subjective auditory features are pointed out.

Animals↗
PubMed1989

Acoustic middle ear reflexes in laboratory animals using clinical equipment: technical considerations.

Acoustic middle ear muscle reflexes (AMR) were examined in nonanesthetized rabbits using clinical oto-impedance devices to determine the feasibility of utilizing clinically available instruments in studies of laboratory animals, particularly with regard to parameters such as probe tone frequency and intensity. The Karolinska Sjukhuset clinical impedance instrument and the Madsen Electronics ZO174 standard clinical impedance meter were used. The results of this study show that reliable AMRs and tympanograms can be obtained from rabbits with both clinical instruments. Probe tone frequencies in the range of 800-1,200 Hz were most effective for eliciting tympanograms and the AMR in rabbits. The probe tone level was also found to be an important factor, with the most reliable sound pressure level being around 70 dB SPL, and below that of the reflex threshold. Both clinical instruments recorded AMR threshold elevations in animals with 7th-nerve and cochlear lesions. AMR decay was observed at 8 and 12 kHz, but no decay was seen in normal-hearing animals up to 4 kHz, suggesting that this frequency may be suitable for detecting and measuring pathological decay in the rabbit. The overall results suggest that standard oto-impedance instruments with a probe tone frequency of 1,000 Hz may be used effectively in experimental studies of several aspects of the AMR in laboratory animals, such as rabbits.

Acoustic Impedance Tests↗
PubMed1988

Eighth nerve fiber firing features in normal-hearing rabbits.

Neural activity of single eighth nerve fibers was recorded with glass microelectrodes in anesthetized normal-hearing rabbits. The units had a spontaneous rate ranging from 0 to approximately 120 spikes/s. In a large number of fibers this rate was below 2 spikes/s. The frequency tuning curves (FTCs) had a tip and a tail region for fibers with a high or medium characteristic frequency (CF). For low-frequency units the FTC was more symmetrically U-shaped. The tip threshold reached the behavioral threshold and units with thresholds of up to more than 60 dB above the mean behavioral threshold were found. There was a weak negative correlation between spontaneous rate and tip threshold. Frequency selectivity, Q10, was about 2 for units with CF below 2 kHz and about 5 for those with CF above 4 kHz. The peristimulus time (PST) histogram showed an initial peak, a plateau, and poststimulus inhibition. For the majority of fibers the dynamic range was 20-30 dB. Some fibers did not reach saturation within the stimulus intensity available. The tip-to-tail distance was 50 dB for high-frequency units at one octave below CF, a matter of potential interest for further studies of animals with inner ear lesions.

Animals↗
PubMed1987

Ototoxicity of cisplatin.

Ototoxicity is one of the unwanted side effects of cisplatin treatment. The first sign of hearing loss usually appears 3-4 days after the drug administration and occurs primarily in the higher frequencies. One hundred and eighty-six women treated with a moderate dose of cisplatin (50 mg/m2 every 4 weeks) for gynaecological cancer were studied. No significant loss of hearing was detected in the speech frequency range. Since the cisplatin concentration in the inner ear is highest after a single high dose injection, systemic audiometric monitoring is advisable during cisplatin therapy with single high dose regimen.

Animals↗
PubMed1987

An ultrastructural and functional study of the inner ear after administration of hyaluronan into the middle ear of the guinea pig.

A single dose of hyaluronan, 19 mg/ml was administered into the right middle ear cavity of guinea pigs. The auditory function of the right ear was tested by recording the gross neural action potential (N1) before, directly after, and 28 days after the administration of hyaluronan. In a control group the right ear was sham-operated and the gross neural action potential (N1) was recorded twice; on the day of the sham operation and 28 days later. All animals were killed 28 days after the operation. All treated as well as sham-operated ears and every second intact ear were studied by scanning electron microscopy (SEM.) No ear had signs of hearing deterioration. Macroscopically, most of the hyaluronan was eliminated from the middle ear after 28 days. In the histological examination, pathological stereocilia were found in the apical turn of the cochlea in the ears to which hyaluronan was administered, the sham operated and the intact ears.

Animals↗
PubMed1987

Selected pathological findings in the human cochlea.

Out of a material of 45 patients with known audiograms where the inner ears had been fixed with an aldehyde within 7 h after death, 4 cases were chosen for detailed morphological examination. The general findings in the ageing human cochlea are presented as well as the findings in the 4 specific cases.

Aged↗
PubMed1986

A study of changes in the information routines in a neurological ward.

The purpose of this study was to investigate whether changes in the method of organizing medical and nursing care in the neurological ward would affect the patients' satisfaction with information during their stay in the ward. The changes consisted of systematic information routines, systematic follow-up and feedback of information which was provided by a 'mentor' system and systematic routines for written communication between informants and 'mentors' about the patients' need for information. A general improvement of the information to the patients occurred. General information was judged almost completely adequate with the aid of the new routines. The effect of the organizational changes upon the patients' satisfaction with medical information could not be fully studied. The physicians continued to give information about diagnosis, prognosis and after-care very late during the patients' hospital stay and this information was not followed up at all during the experimental period.

Adolescent↗
PubMed1986

Communication and decision-making in a study of a multidisciplinary team conference with the registered nurse as conference chairman.

It was decided that the medical and nursing staff had to communicate verbally concerning the patient's need for information and to make decisions concerning steps to be taken when satisfying the patient's need for information. The aim of this study was, accordingly, to investigate if a training programme for registered nurses as chairperson of the multidisciplinary team conference (MTC) changed the communication and decision pattern during the neurological ward conference. The training material provided instructions and a scheme for the chairperson of the MTC. The training was carried through with the help of patient case reports and role play. Data were collected through tape recordings of the communication at ten MTCs before the training and ten MTCs after the training. The strictly medical communication was less illuminated, while the patient's psychological needs, especially concerning the patient's need for information, were better illuminated than before the training. After the training 42 information problems were reported and two before. For half of them, decisions were made on the steps to be taken in order to fulfil the patient's need. For the other half, the discussion concerning the patient's need for information was communicated between the staff. Only the decision-making was missed.

Communication↗