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Biomedical subjects

E Hultcrantz

Publications and source records attributed to E Hultcrantz.

At least 37 records · Page 2Linked to original sources
PubMed1988

Cochlear blood flow increases after systemic hemodilution: comparison of simultaneous laser Doppler flowmetry and radioactive microsphere measurements.

Guinea pig cochlear blood flow was measured before and after systemic normovolemic hemodilution with high molecular weight dextran. Absolute determinations of blood flow (in the cochlea, brain, kidney and lung) were accomplished by use of radioactive-labeled (85Sr or 141Ce) microspheres. Relative measurements of the cochlear blood flow changes were made simultaneously by the use of a laser Doppler flowmeter. The flowmeter probe was placed on the first cochlear turn. Hemodilution to an average systemic hematocrit of 20% increased cochlear blood flow by 250% as measured with microspheres. The laser Doppler instrument significantly underestimated the actual flow increase giving an indication of 148%. Furthermore, the data, when analyzed on an individual trial basis, showed a very poor correlation between the two methods. The theoretical basis for these findings in relation to the use of the laser Doppler instrument is discussed.

Animals↗
PubMed1988

Children with tonsillar obstruction: indications for and efficacy of tonsillectomy.

One hundred and twenty-two children between 1 1/2 and 14 years of age with symptoms suggesting tonsillar obstruction have been investigated. Each patient's history was analysed and the symptoms scored according to their incidence and severity. In addition, the size of the tonsils was evaluated. Eighty-five patients were chosen for tonsillectomy. The children with signs and symptoms of tonsillar obstruction improved greatly immediately after tonsillectomy. Severe symptoms of obstruction were observed in children with nearly normal tonsil size, as well as in those with very large tonsils. It is therefore just as important to obtain a careful history as it is to evaluate the size of the tonsils before deciding about surgery.

Adolescent↗
PubMed1988

The microsphere method for studies of inner ear blood flow.

The microsphere method was adapted in 1974 for studies of cochlear blood flow. Since then it has been used in Uppsala, Sweden, at the Department of Otolaryngology, University Hospital, for investigations of the blood flow circulation in the inner ear. The experience with the technique, the subjects, the actual projects and the results are presented and discussed.

Animals↗
PubMed1988

Sleep apnea in children without hypertrophy of the tonsils.

Two 12-year-old boys with severe sleep apnea syndrome but normal-sized tonsils were satisfactorily corrected by tonsillectomy and uvulopalatopharyngoplasty. One of the boys had muscular hypotony as contributing cause of the condition. The other had mandibular hypoplasia in combination with a long soft palate. Thorough preoperative anamnesis and examination in a sleep laboratory are necessary to determine which cases will benefit from surgery in spite of normal-sized tonsils and which surgical procedure will be most helpful.

Child↗
PubMed1982

Cochlear blood flow related to hyperosmotic solution.

Glycerol and urea can induce positive threshold shifts in Menire's disease whereas mannitol and ethanol do not seem to possess this ability. As an impaired blood supply is suspected to be part of the mechanism behind Menière's disease, the difference in ability of the various hyperosmotic solutions to improve hearing might depend on different effects on the cochlear blood flow. The microsphere method was used to study the cochlear blood flow in albino rabbits before and after administration of hyperosmotic solutions of glycerol, urea and mannitol. The cochlear blood flow increased by about 30% after administration of all solutions. As no difference was found in the effect on cochlear blood flow by the different substances and as the increase in cochlear blood supply was only modest, it would appear that the increment of cochlear blood flow is not a main factor behind the hearing improvements in Menire's disease after glycerol and urea ingestion.

Animals↗
PubMed1982

Effect of nicotinic acid on cochlear blood flow.

Effects of nicotinic acid on cochlear blood flow were studied in rats by the microsphere method. One measurement was performed before drug administration and the second after i.v. injection of the nicotinic acid 25 mg/kg body weight. No measurable effect on cochlear blood flow was observed in normal animals. In one group of animals the cervical sympathetic trunks were cut and the distal part on one side was electrically stimulated during the measurements. On the unstimulated side the cochlear blood flow was significantly higher than in intact animals, but uninfluenced by nicotinic acid. On the sympathetically stimulated side a significant increase of the cochlear blood flow occurred after nicotinic acid administration.

Animals↗
PubMed1982

The effect of glycerol on cochlear blood flow.

Cochlear and cerebral blood flows were measured in albino rabbits by the microsphere method before and 15 min after intravenous administration of glycerol. Both cochlear and cerebral blood flow were significantly increased. The increase in cochlear blood circulation is interpreted as a contributory factor in producing the improvements in hearing threshold seen in the positive glycerol test in Ménière's disease.

Animals↗
PubMed1981

Effect of ethanol on cochlear blood flow.

The cochlear and cerebral blood flow was studied in rabbits with the microsphere method before and 15 min after i.v. administration of ethanol. In a series of control experiments only saline was injected. No alteration was measured in the cochlear and cerebral blood flow after the administration of saline, whereas both cochlear and cerebral blood flow showed an increase after ethanol administration. The results are discussed in relation to changes in serum osmolality and hearing in patients with Menière's disease.

Animals↗
PubMed1981

Does loud sound influence the intracochlear oxygen tension?

The effect of loud sound on the perilymphatic oxygen tension was studied in anesthetized guinea pigs. Pure tone (4 kHz) and broad-band noise were given at 85-130 dB SPL for 3-8 min. No effects were seen either in the animals exposed to pure tone or in the animals exposed to 85 dB broad-band noise. In the animals exposed to noise at 130 dB SPL both increases and decreases of perilymphatic oxygen were measured but the changes were only of about 12% or less. The response to anoxia was normal. In animals with hypotension ( less than 8 kPa) the perilymphatic PO2 fluctuated with the blood pressure. When the sound was delivered directly into the opened bulla the measured PO2 dropped immediately but was found to be caused by the cooling effect of an air current produced by the noise. Flushing the opened bulla with nitrogen, air or oxygen caused the same temperature-induced drop of measured PO2. The results and the artifacts are discussed.

Animals↗
PubMed1980

The effect of CO2-breathing on cochlear blood flow.

The cochlear blood flow was measured with the microsphere methods, before and during CO2-inhalation, in anesthetized rabbits. Different gas mixtures and exposure times were used. The greatest increase of cochlear blood flow was measured after 5 min inhalation of 7% CO2 in air (115%) and the least increase (44%) in animals breathing 7% CO2 in oxygen. The difference is explained as due to a vasoconstriction caused by a high oxygen tension counteracting the vasodilating effect of CO2.

Acidosis, Respiratory↗
PubMed1980

Early effects of cervical sympathetic stimulation on cerebral, ocular and cochlear blood flow.

Autoregulatory mechanisms may be expected to modify effects of vasomotor nerve stimulation in many tissues. Attempts were made to reveal a distinct early, but transient effect of cervical sympathetic stimulation on cerebral, retinal and cochlear blood flow. The labelled microsphere method was used to determine regional blood flow during electrical stimulation of the cervical sympathetic chain for 15-25 s and 5 min. At a frequency of 6 Hz there was 5% reduction in cerebral flow at 15-25 s and 7% at 5 min. In the choroid plexus the mean reduction was 22% at 15-25 s but decreased 10% after 5 min. In the cerebellum, optic nerve and retina, sympathetic stimulation had no appreciable effect on the blood flow. In the cochlea and iris, the blood flow reductions were 25 and 32%, respectively, on both occasions. In the choroid, vasoconstriction increased with time, whereas in the masseter muscle there was a decrease. Thus in the present experiments no indication was found of an autoregulatory escape phenomenon in the brain, the eye or the cochlea. Some escape was noted in the masseter muscle.

Animals↗
PubMed1980

Effects of CO2 inhalation on cochlear blood circulation.

The cochlear blood flow was measured with the microsphere method before, during and after CO2 inhalation in anesthetized rabbits. Different gas mixtures and exposure times were used. The greatest increase of cochlear blood flow was measured after 5 min inhalation of 7% CO2 in air (115%) and the least increase (44%) in animals breathing 7% CO2 in oxygen. The difference is explained as due to a vasoconstriction caused by a high oxygen tension counteracting the vasodilating effect of CO2. The treatment with CO2 of supposed vascular diseases in the cochlea is discussed and the negative effects due to respiratory acidosis are emphasized.

Animals↗
PubMed1979

Noise and cochlear blood flow.

The effect of noise after unilateral transection of the cervical sympathetic trunk on cochlear blood flow was studied in anesthetized cats. The sound pressure level was 100 dB and the exposure time 6 min. Neither noise nor sympathectomy were found to affect the blood flow.

Animals↗
PubMed1979

The effect of noise on cochlear blood flow in the conscious rabbit.

The cochlear blood flow was measured with the microsphere method in unanesthetized rabbits, prior to and during noise-exposure. Different sound pressure levels were used: 100 dB, 115 dB and 120 dB. Some of the animals had the cervical sympathetic trunk cut unilaterally. The effects of the delivered noise on the organ of Corti were studied in other rabbits with scanning electron microscopy. In spite of ultrastructural changes indicating damage of sensory cells after 115 dB and 120 dB exposure no changes of the total cochlear blood flow could be observed. After unilateral section of the cervical sympathetic trunk the cochlear blood flow was less on the intact side (25%) already prior to noise exposure and the difference was not significantly affected by noise. Different sizes of microspheres were used: 8.2, 8.4, 8.7, 9,2 mum. The 8.2 and 8.4 mum-spheres seemed well fitted for measurements of cochlear blood flow but passed the cerebral capillaries to a high extent. Control experiments using both 8.2/8.4 mum-spheres and 15 mum-spheres were performed and the degree of passage in different tissues was estimated.

Animals↗