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Biomedical subjects

C Angelborg

Publications and source records attributed to C Angelborg.

At least 19 recordsLinked to original sources
PubMed1994

The cochlear blood flow: a comparison between the laser Doppler and the microsphere surface methods.

Since the introduction in the early 1980s, of the laser Doppler (LD) method for measuring cochlear blood flow (CBF) it has been debated whether the measured changes reflect the total or regional blood flow and whether the method per se influences the CBF. In order to answer those questions, the effect of one vasodilating drug, sodium nitroprusside, was investigated after topical application on the round window membrane (RWM) with respect to its influence on CBF. Two different techniques, the microspheres surface method and the LD method, were used. Untreated animals and animals which received saline or nicotine acid on the RWM were used as controls. The effects on CBF and blood pressure (BP) were continuously registered with LD. When a maximal flow had stabilized, 6 x 10(6) microspheres were injected into the left side of the heart. After the microspheres had been distributed within the body, the animals were killed. Both cochleae were microdissected and the microspheres counted turn by turn in the lateral wall. The number of spheres in the two ears was compared and the difference was recorded as the increase caused by the drug. The percentage change in CBF measured using the LD was compared with that obtained by using the microsphere surface method (MSM). No change in CBF measured by the two techniques was registered in the untreated animals, or after saline or nicotinic acid, while sodium nitroprusside induced a substantial increase in CBF. The mean percentage change of CBF measured with the LD method was compared with the calculated mean percentage change of microspheres for all turns in the cochlea, and in the first turn. Student's t-test and the linear correlation coefficient were calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1994

Ultrasound treatment of Ménière's disease.

This article reviews the technical data about ultrasonography devices, the mode of action of ultrasound waves on vestibular structures, when to use this technique, and the surgical procedure. It also presents the results of this treatment obtained during the last 10 years in the authors' various institutions.

Adolescent↗
PubMed1991

Low-pressure chamber test in Menière's disease.

Lowering of the ambient pressure has been reported to have a positive effect on the symptoms in Menière's disease. In order to further investigate this hypothesis the symptoms in the long-term span were studied in 54 Menière patients who had undergone low-pressure chamber tests. Lowering of the ambient pressure can induce a temporary but not a permanent hearing improvement in patients with Menière's disease. The results also indicate positive effects on other symptoms in Menière's disease, but this could not be statistically proven.

Atmosphere Exposure Chambers↗
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

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↗
PubMed1987

Colored microspheres for blood flow determinations twice in the same animal.

The regional cochlear blood flow has been studied in the rabbit cochlea by mapping the distribution of non-radioactive microspheres in serial sections of plastic embedded cochleas. By using microspheres of two different colors injected at two different times, it is now possible to measure the 'regional' cochlear blood flow twice in the same animal.

Animals↗
PubMed1987

Effect of galactose and isosorbide on cochlear blood flow.

Cochlear blood flow in the rabbit was determined before and after injection of hyperosmotic solutions of galactose and isosorbide. After doses similar to those which can produce hearing improvements in patients with Ménière's disease, cochlear blood flow was increased by 30-60%.

Animals↗
PubMed1987

A histopathological study of the inner ear after the administration of hyaluronan into the middle ear of the guinea pig.

Hyaluronan, 19 mg/ml, was administered into the middle ear cavity of guinea pigs. A control group was subjected to a sham operation. Fourteen days after administration the animals were killed and a macroscopic examination of all middle ears was performed. Surface preparations of the organ of Corti were made and examined by light microscopy. Hair cell loss along the length of the sensory epithelium was quantified. No toxic effect of hyaluronan could be detected either in the middle ear or in the sensory cells in the cochlea. Thus hyaluronan is potentially useful for facilitating middle ear surgery.

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↗
PubMed1986

Pharmacological treatment of Menière's disease. A review of common remedies with special emphasis on vasodilators, including hyperosmolar substances and hearing.

A review is given of common pharmacological therapies for Menière's disease. The use of vasodilators and hyperosmotic agents is discussed on the bases of clinical and experimental investigations. Osmotic reduction of intralabyrinthine water seems to play a major role in the induced hearing gain but positive effects on the inner ear blood flow cannot be excluded.

Hearing↗
PubMed1985

Blood flow in the peripheral vestibular system.

A quantitative estimation of the vestibular blood flow was made in normal rabbits using the microsphere method. The total inner ear blood flow was 4 mg per minute, the cochlear blood flow was 3 mg per minute, and the vestibular blood flow was 1 mg per minute.

Animals↗
PubMed1984

Regional blood flow in the rabbit cochlea.

A new technique evaluates microcirculation in the different parts of the cochlea. It is a synthesis of two previously known methods--the microsphere method and the soft surface-specimen method. We studied the cochlear blood flow in ten albino rabbits using nonradioactive microspheres. The local distribution of microspheres in the cochlea was determined and the total cochlear blood flow calculated.

Animals↗
PubMed1984

Determination of the regional cochlear blood flow in the rat cochlea using non-radioactive microspheres and serially sectioned cochleas.

The regional blood flow to the rat cochlea has been studied using a method which combines the microsphere method with observation of serially-sectioned, plastic-embedded cochleas. Direct quantitation of the microspheres in a reference blood sample and in the different vascular areas of the cochlea allows the analysis of blood flow patterns with respect to the different capillary beds.

Animals↗
PubMed1984

Computerized reconstruction of the regional blood flow in the rodent cochlea.

The regional blood flow in the cochlea has been studied by mapping the distribution of microspheres in 22 micron thick serial sections of plastic embedded rat and rabbit cochleas. Using a computer-assisted reconstruction technique, a graphic display of the microspheres in each cochlea is obtained. From this display, microspheres may be counted and their distribution may be observed both in relation to the different vascular areas and with respect to the length of the cochlea. This technique, coupled with quantitation of the microspheres in a reference blood sample, offers a method for calculating total and regional cochlear blood flow using non-radioactive microspheres. In addition, this technique allows analysis of blood flow patterns with respect to the different capillary beds along the length of the cochlea. Thus it may be possible to determine if regional blood flow displays a longitudinal gradient, as do other functional, morphologic and biochemical characteristics of the cochlea.

Animals↗
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↗