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At least 271 records · Page 15Linked to original sources
PubMed1982

Immunologic study on the inner ear. Immunoglobulins in perilymph.

The immunoglobulin composition of perilymph (PL) was measured using electroimmunodiffusion, and transfer of serum antibodies to PL was studied using a passive hemagglutination test in chinchillas and guinea pigs. The mean values of IgG an albumin in PL were two to four times greater than those in CSF. In guinea pigs, IgA was found in 93% of the PL and 32% of the CSF samples, but in chinchillas only trace amounts of IgA were found in 50% of the PL and 15% of the CSF samples. No IgM was detected in PL or CSF of either species. This study suggests that a greater portion of the immunoglobulins in PL probably is derived from perilymphatic blood vessels as a filtrate and that the perilymphatic inner ear immune system is independent from that of the CSF.

Animals↗
PubMed2003

Aquaporin-mediated fluid regulation in the inner ear.

1. The sensory functions of the inner ear (hearing and balance) critically depend on the precise regulation of two fluid compartments of highly desparate ion composition, i.e., the endolymph and the perilymph. 2. The parameters volume, ion composition, and pH need to be held at homeostasis irrespective of the hydration status of the total organism. 3. Specific cellular water channels, aquaporins, have been shown to be essential for the fluid regulation of several organs, e.g., kidney, lung, and brain. 4. Because of functional similarities of water regulation in the kidney and inner ear this review initially summarizes some aquaporin functions in the kidney and then focuses on 6 out of 11 mammalian aquaporins that are present in the inner ear (AQP1-6). 5. Their potential role in the inner ear fluid control will be discussed on the basis of the respective expression patterns and individual pore properties. 6. Further, a working model is presented of how the endolymphatic sac may contribute to inner ear fluid regulation.

Animals↗
PubMed1982

X-ray analysis of biological fluids: contribution of microdroplet technique to biology.

Electron probe analysis by x-ray spectrometry is used in biology for simultaneous determination of the concentrations of any elements with a higher atomic number than that of carbon in single samples with volumes of 0.01 to 0.5 nl. In this technique, deposits prepared from identical volumes of biological fluids and standard solutions are totally covered by the electron beam, and the measured x-ray intensities for each element directly compared. The possibility of intensity quantification depends on the thinness of the dried deposits obtainable by various preparatory techniques. Factors affecting the accuracy of the results include droplet stability under the electron beam, the identity of the degree of oxidation of the elements in biological fluids and standards, sample mass thickness, beam voltage, and matrix effects. Minimum detectable concentrations in the 0.05 mmol.l-1 range are now achievable. This technique is the only one applicable in cases where available volumes are too small to determine the concentrations of several elements on the same sample (for instance of Na, Mg, S, P, Cl, K, Ca, Fe and Co), or even to determine the concentration of a single element (e.g. Mg). Although the droplet technique has so far mainly been used in renal physiology, it has also been applied in reproductive and digestive physiology. Isolated cells are analyzed according to the same principle of totally covering the cell by the electron beam. During the last decade, the vast increase in the relevant literature has testified to the contribution of the microdroplet technique to various fields of biology.

Absorption↗
PubMedDate not supplied

Effect of increased perilymphatic pressure on endocochlear potential.

A study was done to determine how increased fluid pressure in the inner ear influences cochlear blood flow. Hydrostatic pressure was applied to the scala vestibuli or scala tympani in guinea pigs. Endocochlear potential, which is sensitive to the lack of oxygen, was measured through the round window membrane or through the stria vascularis. Cochlear blood flow was confirmed by intravenous injection of India ink. When the perilymphatic pressure was raised to a relatively high level, endocochlear potential decreased, ina similar way as in response to anoxia, because of the cessation of the cochlear blood flow. This change was completely reversible upon applications of pressure for brief periods of time. We consider that the cochlear blood flow ceases when the fluid pressure reaches the level of intracochlear arterial pressure.

Animals↗
PubMedDate not supplied

Pathology of Ménière's disease as it relates to the sac and tack procedures.

The rationale for endolymphatic sac and tack operations is to prevent the further accumulation of endolymph, the former by draining endolymph into extralabyrinthine tissues and the latter by shunting endolymph into the perilymphatic space. While the basic concepts are reasonable enough, the probability of achieving these objectives seems remote. There appears to be adequate clinical evidence, however, to show that these procedures are of therapeutic value in selected cases. It is tempting to speculate that these surgical insults to the labyrinth, with the associated inflammatory and biochemical changes, alter the function of cells which control fluid physiology and thus improve the symptoms of Ménière's disease.

Adult↗
PubMed1989

Congenital perilymphatic fistula: a prospective study in infants and children.

A 3-year prospective study of 244 children (aged 5 months to 17 years) with sensorineural hearing loss of unknown cause revealed that 57 children (23%) had radiographic evidence of abnormalities of the temporal bone, detected by computed tomography scan, and/or progression of sensorineural hearing loss. Of these 57 children, 42 (74%) underwent surgical exploration, with 15 children (26%) of this subgroup demonstrating active congenital perilymphatic fistula. The prevalence of congenital perilymphatic fistula in a large, closely monitored population of children with unexplained sensorineural hearing loss appears to be at least 6% (15 of 244 children). The incidence may be higher because some congenital perilymphatic fistulae may leak intermittently and not be observed during middle ear surgery. Therefore, in children with suspected sensorineural hearing loss, early and frequent audiological evaluations should be made to rule out progressive/fluctuating sensorineural hearing loss. These children should also have radiographic imaging of their temporal bone by computed tomography scan. The use of both methods is the best indicator for congenital perilymphatic fistula.

Adolescent↗
PubMedDate not supplied

Effects of carbon dioxide in the middle ear cavity upon the cochlear potentials and cochlear pH.

To elucidate the effects of CO2 in the middle ear upon the cochlea, measurements were made of the cochlear potentials (compound action potential and endocochlear potential) and of the pH of the inner ear fluids and the organ of Corti. Gas containing CO2 did not affect the AP threshold, except for a slight decrease in AP threshold elicited by an 8 kHz tone burst with 10% CO2 flow. The EP did not vary with CO2 gas. The CO2 gas mixture reduced the pH in perilymph significantly, by 0.11 +/- 0.05 with 5% CO2 and by 0.17 +/- 0.04 with 10% CO2, in comparison with 100% N2. The CO2 gas slightly but significantly decreased the endolymph pH, by 0.05 +/- 0.04 with 5% CO2 and by 0.09 +/- 0.06 with 10% CO2. The removal of perilymph led to a greater acidification of endolymph with CO2 gas. Acidification of the organ of Corti was also noted with the CO2 gas flush. These findings indicate that CO2 in the middle ear influences the acid-base regulation of inner ear fluids and the cochlear function.

Animals↗
PubMed1986

Production of endolymph in the semicircular canal of the frog Rana esculenta.

The mechanisms of secretion of endolymph were studied in vitro in the isolated inner ear of the frog. Prior to in vitro experiments, the composition of perilymph was evaluated in vivo and compared to that of plasma. Composition of perilymph resembled that of an extracellular fluid, although Na and Cl concentrations were higher and K concentration was lower in perilymph than in plasma water. No difference in Ca and Mg concentrations was observed between these two fluids. Osmolality averaged 227 mosmol/kg H2O in perilymph and 183 mosmol/kg H2O in plasma. Endolymph in frog inner ear corresponded in chemical pattern to mammalian endolymph. K and Na concentrations in endolymph collected from the ampulla of the posterior vertical semicircular canal averaged 121.1 mM and 2.5 mM, respectively. Osmolality of endolymph was 237 mosmol/kg H2O. K and Na concentrations were unaltered when inner ears were incubated for 24 h either at 15 degrees C or at 4 degrees C. Addition of ouabain (10(-4) M) to the perilymph-like bathing solution altered greatly Na and K composition of endolymph after incubation for 3 h at 15 degrees C. The Na and K concentration gradients between endolymph and the bath were abolished after incubation for 24 h. Ligatures of the posterior vertical semicircular canal were performed at different sites to isolate some parts of the canal, i.e. the ampulla and the non-ampullar duct. K concentration in the ampulla after incubation for 24 h remained as high as 20 times that in the bath. This K gradient was abolished in the presence of ouabain (10(-4) M). High K concentration could be maintained in the non-ampullar part of the semicircular canal only if the latter communicated with the ampulla. It is concluded that endolymph is actively secreted into the ampulla of the semicircular canal. Na+-K+-activated ATPase in the ampullar dark cells may energize the ouabain sensitive ionic transports that are involved in the production of endolymph. Endolymph secreted into the ampulla would spread intraluminally to account for the high K and low Na concentrations of the fluid which fills the non-secretory part of the semicircular canal.

Animals↗
PubMed1988

Development of pressure monitoring and controlling system for quantitative analysis of experimentally induced perilymph fistula.

The cause of perilymph fistula, a subgroup of sudden deafness, has not been clearly understood. To study its etiology quantitatively, the inner ear pressure monitoring system with a computer controlled pressurizing device and three types of low-pressure monitoring sensors was constructed and utilized in ex vivo experiments using white guinea pigs. Hypothesizing that cerebrospinal pressure increases cause rupture of the round window membrane, direct and indirect pressurization to cerebrospinal region and simultaneous measurement of inner ear and cerebrospinal pressures were carried out. Ruptures of the round window membranes were seen in the experiments with direct saline infusion into the cochlea when the increment of inner ear pressure exceeded 500 mmH2O. There was no sign of rupture when squeezing abdomen was employed as an indirect pressurization, although cerebrospinal pressure increased.

Animals↗
PubMed2003

Expression of G protein alpha subunits in the lateral wall of the rat cochlea.

Expression of five G protein alpha subunits was investigated in the rat cochlea by reverse transcription-polymerase chain reaction (RT-PCR) in order to understand their role in the cochlear signal transduction mechanisms. Immunohistochemical techniques were employed to study their distribution in the lateral wall of the cochlea. Total RNA was extracted with guanidine thiocyanate from cochleas and brains of 14-21-day-old rats. The extract was treated with DNase to degrade genomic DNA. After RT, the resulting cDNA was amplified by PCR using primers specific for the nucleotide sequences representing alpha subunits of heterotrimeric G proteins. The results indicated that mRNA for all five alpha subunits was expressed in the brain and cochlear samples. For immunohistochemical localization, temporal bones of 6-week-old rats were fixed in 4% paraformaldehyde and 0.1% glutaraldehyde and processed for embedding in paraffin wax. The dewaxed, midmodiolar sections of the cochlea were incubated with subunit-specific polyclonal antibodies. The pattern of immunoreactivity varied for the five G protein alpha subunits studied in the stria vascularis and spiral ligament. The significance of these findings and the role of G protein alpha subunits in cochlear fluid homeostasis are discussed.

Animals↗
PubMed1981

X-ray microanalysis of fluid spaces in the frozen cochlea.

The cochlea is quick-frozen and then opened while under liquid nitrogen to expose the scalae of all turns in the mid-modiolar section. Still under liquid nitrogen, the cochlea is transferred to the cold stage of a pre-vacuum chamber especially constructed for attachment to the scanning electron microscope. Under partial vacuum, it is moved to the cold stage in the high vacuum chamber of a field-emission scanning electron microscope. Energy dispersive X-ray analysis demonstrates the relative levels of sodium, potassium, and chlorine in the fluid spaces of the cochlea.

Animals↗
PubMed1980

Detection of endotoxin in ear specimens from patients with chronic otitis media by means of the limulus amebocyte lysate test.

The limulus amebocyte lysate (LAL) test is the most sensitive procedure for the detection of endotoxic lipopolysaccharides. The test was applied to middle ear fluids, cholesteatomas, and granulation tissue specimens from 31 patients in parallel with bacteriologic examination. The LAL test and bacteriologic examination yielded concordant results with 26 out of 28 specimens. A positive LAL test was obtained with 11 specimens containing endotoxin-producing organisms. The test became positive within 60 min of incubation in 10 out of 11 specimens and in 1 specimen between 1 and 24 h, suggesting that, in the majority of specimens, endotoxin was present in the specimen itself and that the result was not due to the in vitro multiplication of the microorganisms. All negative tests remained negative for 24 h. It is conceivable that endotoxin present in ear fluids may contribute to the pathologic changes in chronic otitis media.

Adolescent↗