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PubMedDate not supplied

Non-collagen proteins of stapedial bone matrix in perilymph of otosclerotic patients.

Non-collagen proteins extracted from the otosclerotic stapes footplate, superstructure and temporal cortical bone were compared with the protein patterns of normal and otosclerotic perilymph by analytical isotachophoresis (ITP). Normal and otosclerotic perilymph yielded basically identical isotachophoretic subfractions. Thirteen subfractions were detected moving as anions at pH 9.6 in the normal perilymph, versus 16 subfractions of similar character in the otosclerotic perilymph. Of these 16 protein subfractions, one (which was not detected in the normal perilymph) could be found in the ITP-gram of the stapes footplate non-collagen proteins, but not of the stapes superstructure or temporal cortical bone. Our results support the concept that protein can enter the inner ear fluid spaces from the otosclerotic bone. The biological significance of these proteins has not yet been clarified.

Bone Matrix↗

PubMed1982

Analysis of the phamacokinetics of ribostamycin in serum and perilymph of guinea pigs after single and multiple doses.

The pharmacokinetics of ribostamycin in serum and perilymph of guinea pigs was studied after a single s.c. injection of 400 mg/kg or 14 daily injections of the same dose. The repetitive administration of ribostamycin did not produce functional impairment of the kidney and ototoxicity was slight. The pharmacokinetic data were analysed by non-linear least mean squares regression. Ribostamycin did not accumulate in either serum or perilymph after multiple dosing. The half-life of the drug in perilymph was 15.8 h after a single injection, but 7.6 h after the last of 14 injections. The area under the ribostamycin concentration in perilymph against time curve was also reduced after multiple dosing. These changes were found to be due to a marked increase in the rate of transfer of the drug from perilymph to serum after multiple dosing.

Animals↗

PubMed1979

[Blockage of cochlear aqueduct for examination of perilymph (guinea pig) (author's transl)].

To prevent the perilymph (guinea pig) from contamination with CSF during the sampling the aqueductus cochleae (AC) was blocked by injection of tissue adhesive into the meningeal aperture. The control of an exact blockage of AC was carriedout by examination of perilymph-outflow after opening the cochlea (injection of fluorescein-Na into the CSF-space), analysis of perilymph-protein-concentration, macroscopic and microscopic examination of the temporal bones. In all cochleae we have found the same morphological structures, notwithstanding whether the AC was blocked (for a time from 30 min to 7 weeks) or not: The cochlear aqueduct is filled with a mesh of mesenchymal tissue, which grows more dense towards the cochlear aperture andcontinues into the round window membrane. From scala tympani the AC is always limited by one layer of cells forming a sort of membrane (under light microscope). It seems possible that CSF moves in the inner of the round window membrane between AC and subepithelian space of middle ear mucosa, whereas perilymph of scala tympani is not in direct contact with the flow of CSF. The scala tympanic side of the round window membrane may be a big area for diffusion and there also may be an exchange between CSF and perilymph. The outflow of CSF into the cochlea after experimental opening of the cochlea is an artifact, caused by damage of pressure equilibration between CSF-space and cochlea. 30 min and 5--7 weeks after blockage no morphologicaland electrophysiological alterations from those of the control ears were to be seen. The protein concentration, however, increased significantly 5--7 weeks after blockage from normally about 200 mg/100 ml toalmost the double especially in the scala tympani (see Table 1).

Action Potentials↗

PubMed2003

Detection of human cytomegalovirus DNA in perilymph of patients with sensorineural hearing loss using real-time PCR.

Although cytomegalovirus (CMV) has been detected in the inner ear fluid of patients who succumbed to the complications of symptomatic congenital CMV infection, it has not been detected in the inner ear fluid of living patients. In this study, real-time polymerase chain reaction (PCR) was used to measure CMV DNA in clinical samples (including perilymph) collected from five patients with deafness. In case 1, diagnosed as a symptomatic congenital CMV infection, 3 copies/microl of CMV DNA were detected in perilymph, although no viral DNA was detected in peripheral blood mononuclear cells (PBMCs) or urine samples. In case 4, a suspected asymptomatic congenital CMV infection, 36 copies/microg of CMV DNA were detected in PBMCs, but neither perilymph nor urine contained viral DNA. Likewise, in case 5, a case of deafness of unknown origin, 48 copies/microg of CMV DNA were detected in the PBMCs, but none in the perilymph or urine. CMV DNA was not detected in the samples obtained from the remaining two cases with deafness of unknown etiology. To our knowledge, this is the first report to detect CMV DNA in an inner ear sample obtained from a living human subject.

Adult↗

PubMed1990

Susceptibility of the endocochlear potential to pH and osmolarity changes in the perilymph of the cochlea in the guinea pig.

The effects of artificial perilymph at various pH levels and osmolarities on the endocochlear potential (EP) were investigated in a guinea pig model. In 47 ears, the mean EP was 74.5 +/- 0.5 mV in the second turn of the cochlea before perilymphatic perfusion. The artificial perilymph with a pH ranging from 5 to 9 and tonicity less than 1.25 (osmolarity, 345 mosmol/l) did not alter the EP when testings were recorded for at least 1 h. However, after the start of a perfusion with a pH less than 4, the EP declined gradually but recovered to the pre-perfusion level rapidly when the perfusion was stopped. The artificial perilymph with a pH over 10 decreased the EP considerably but showed no recovery, even after cessation of the perfusion. Tonicity more than 1.35 (osmolarity, 372.6 mosmol/l) also decreased the EP, with this decrease paralleling further increases in the tonicity used. From these data, we have concluded that a perilymph perfusate with a pH from 5 to 9 and an osmolarity less than 350 mosmol/l can be used in animal testing without any noxious effects on the EP.

Animals↗

PubMed1984

The effect of furosemide on sodium and potassium concentrations in guinea-pig perilymph.

To observe the effects of furosemide on electrolyte concentrations in inner-ear fluids, experiments were performed on 286 normal guinea-pigs. Intravenous injection of furosemide (15 mg/kg) induced increases of Na concentration in scala tympani perilymph, scala vestibuli perilymph, and cerebrospinal fluid (CSF). K concentrations in both perilymphs and CSF were also increased by furosemide. The increased Na concentrations are thought to be due to the dehydration of body fluids induced by the diuretic action of furosemide. The increase of K concentrations in perilymphs could be attributable to either a characteristic action of furosemide on the electrolyte transport in the inner ear or a secondary change caused by a rise of K concentration in the endolymph.

Animals↗

PubMedDate not supplied

Perilymph fistula: a cause of auditory, vestibular, neurological and psychiatric disorder.

It is suggested that damage by mild trauma, viruses or bone disease to the otic capsule or to the membranes between the cochlea and the middle ear is common, and involved in many syndromes of obscure etiology. The clinical perilymph fistula (PF) syndrome can consist of any combination of the following: tinnitus, deafness, phonophobia, vertigo, ataxia, otalgia, facial palsy, headache, diplopia, blackouts, psychological distress. The following testable hypotheses are proposed: otitis media is due to perilymph in the middle ear, with secondary changes resulting from infection or inflammation: otosclerosis results from a slow leak in the presence of enzymes promoting bone growth: Meniere's syndrome follows reduced perilymph support for the endolymphatic system: Bell's palsy results from a perilymph provoked oedema in the bony facial nerve canal: PFs may be responsible for progressive rubella deafness, and for some cases of migraine, epilepsy, anxiety neurosis and hysteria: psychiatric sequelae of the PF syndrome predominate in the post-concussional syndrome and infantile autism: organisms can pass from the throat into the spinal fluid, causing meningitis or encephalitis. The tinnitus and vertigo are caused by random labyrinthine fluid movements, the headache and diplopia by reduced spinal fluid pressure.

Deafness↗

PubMed1984

Permeability to sodium ions of the endolymph-perilymph barrier.

The endocochlear potential and Na+ activity in the endolymph were simultaneously measured with a double-barreled Na+ selective liquid membrane electrode. The modified Na+ conductance and permeability coefficient of the endolymph-perilymph barrier were calculated from the rate of change in the endolymph Na+ concentration relative to the Na+ electrochemical gradient across the barrier during permanent anoxia. In normal guinea pigs the Na+ conductance of the endolymph-perilymph barrier is approximately 5 times less than its K+ conductance. Exposure to noise or treatment with kanamycin suppresses the cochlear microphonics but does not result in significant alterations in the Na+ permeability of the endolymph-perilymph barrier. It is likely that the Na+ permeability of the endolymph-perilymph barrier is not involved in the physiological processes which lead to the cochlear damage produced by noise or kanamycin.

Action Potentials↗

PubMed1988

Volume flow rate of perilymph in the guinea-pig cochlea.

The rate of longitudinal flow of perilymph has been measured using an ionic tracer technique. Spread of the tracer trimethylphenylammonium (TMPA) along the perilymphatic scalae was monitored with ion-selective microelectrodes following injection of a minute bolus (approximately 50 nl) of 150 mM TMPAC1 one turn away. This amount of TMPA had virtually no toxic effect on cochlear function. The spread of tracer by longitudinal volume flow and passive diffusion were separated by comparing tracer movements in both apical and basal directions along the scalae in two groups of animals. Experimental findings were compared with a mathematical model which combined diffusion and volume flow. Our results demonstrated that when electrodes were completely sealed into the cochlea, the rate of longitudinal volume flow in scala tympani was extremely slow, approximately 1.6 nl/min in the apical direction. Longitudinal flow was not detectable in scala vestibuli. When the otic capsule was perforated, flow rates of over 1 microliter/min were recorded in scala tympani, probably as a result of cerebrospinal fluid entry through the cochlear aqueduct. When the cochlea was sealed (with recording electrodes in place) and cerebrospinal fluid pressure was released, there was no significant basally-directed flow of perilymph in scala tympani. These findings support the concept that perilymph composition is maintained by local, cochlear mechanisms which do not involve longitudinal volume flow. They provide strong evidence that perilymph is not secreted in one region and resorbed at a spatially distant site.

Action Potentials↗

PubMed1989

Perilymph composition in scala tympani of the cochlea: influence of cerebrospinal fluid.

A commonly used technique to obtain cochlear perilymph for analysis has been the aspiration of samples through the round window membrane. The present study has investigated the influence of the volume withdrawn on sample composition in the guinea pig. Samples of less than 200 nl in volume taken through the round window showed relatively high glycine content, comparable to the level found in samples taken from scala vestibuli. If larger volumes are withdrawn, lower glycine levels are observed. This is consistent with cerebrospinal fluid (having a low glycine content) being drawn into scala tympani through the cochlear aqueduct and contaminating the sample. The existence of a concentration difference for glycine between scala tympani perilymph and cerebrospinal fluid suggests the physiologic communication across the cochlear aqueduct is relatively small in this species. The observation of considerable exchange between cerebrospinal fluid and perilymph, as reported in some studies, is more likely to be an artifact of the experimental procedures, rather than of physiologic significance. Alternative sampling procedures have been evaluated which allow larger volumes of uncontaminated scala tympani perilymph to be collected.

Animals↗

PubMed1992

Intense sound increases the level of an unidentified amine found in perilymph.

The hypothesis tested was that intense sound increases the levels of a substance such as glutamate, a putative neurotransmitter and neurotoxic substance, in the perilymph compartment of the cochlea. Artificial perilymph was perfused through the perilymphatic compartment of the guinea pig cochlea and the effluent collected during successive 10-min periods. The effects of perfusing an artificial perilymph containing normal levels of Na+ (NARP) were compared to the effects of perfusing an artificial perilymph containing very low concentrations of Na+ (VLNa). The effluent was collected during ambient noise and during increasing intensities of broad-band noise (10 min at 106, 112, 118 and 124 dB SPL). Levels of amines in the effluent were measured by HPLC utilizing precolumn o-phthalaldehyde (OPA) derivatization and fluorescence detection. VLNa increased the levels of glutamate and several other amines in effluent from the cochlea compared to levels obtained in NARP. Compared with its level during ambient room noise, the concentration of an unidentified amine labeled Unk 2.5 increased during intense noise (124 dB SPL). Intense noise induced no detectable changes in the concentrations of glutamate and fifteen other amines. The chemical identity and role of Unk 2.5 remain to be determined.

Amines↗

PubMed2004

Identification of a novel Cochlin isoform in the perilymph: insights to Cochlin function and the pathogenesis of DFNA9.

The COCH gene mutated in DFNA9, an autosomal dominant hereditary sensorineural hearing loss and vestibular disorder, encodes Cochlin. Previously, we reported three bovine Cochlin isoforms, p63s, p44s, and p40s, which exhibit significant molecular heterogeneity in vivo. Here we have characterized Cochlin isoforms by generating four isoform-specific anti-Cochlin antibodies. The same three Cochlin isoforms, p63s, p44s, and p40s, were detected in human and cow inner ear tissue; however, p44s and p40s were not detected in perilymph. We identified a novel short 16kDa isoform in human perilymph and a 18-23kDa isoform in cow perilymph, named Cochlin-tomoprotein (CTP), corresponding to the N-terminus of full-length Cochlin (p63s) and the LCCL domain. Notably, CTP contains all of the known mutation sites associated with DFNA9. The pathogenesis of DFNA9 is not fully clarified as yet, and this novel perilymph-associated CTP isoform might provide mechanistic clues to how mutations in the COCH gene damage the inner ear function.

Amino Acid Sequence↗

PubMed2001

Quantification of solute entry into cochlear perilymph through the round window membrane.

The administration of drugs to the inner ear via the round window membrane is becoming more widely used for both clinical and experimental purposes. The actual drug levels achieved in different regions of the inner ear by this method have not been established. The present study has made use of simulations of solute movements in the cochlear fluids to describe the distribution of a marker solute in the guinea pig cochlear fluid spaces. Simulation parameters were derived from experimental measurements using a marker ion, trimethylphenylammonium (TMPA). The distribution of this ion in the cochlea was monitored without volume disturbance using TMPA-selective microelectrodes sealed into the first and second turns of scala tympani (ST). TMPA was applied to perilymph by irrigation of the intact round window membrane with 2 mM solution. At the end of a 90 min application period, TMPA in the first turn, 1.4 mm from the base of ST, reached an average concentration of 330 microM (standard deviation (S.D.) 147 microM, n = 8). TMPA in the second turn, 7.5 mm from the base of ST reached a concentration of 15 microM (S.D. 33 microM, n = 5). The measured time courses of TMPA concentration change were interpreted using the Washington University Cochlear Fluids Simulator (V 1.4), a public-domain program available on the internet at http ://oto.wustl.edu/cochlea/. Simulations with parameters producing concentration time courses comparable to those measured were: (1) round window permeability: 1.9 x 10(-80 cm/s; (2) ST clearance half-time: 60 min; (3) longitudinal perilymph flow rate: 4.4 nl/min, directed from base to apex. Solute concentrations in apical regions of the cochlea were found to be determined primarily by the rate at which the solute diffuses, balanced by the rate of clearance of the solute from perilymph. Longitudinal perilymph flow was not an important factor in solute distribution unless the bony otic capsule was perforated, which rapidly caused substantial changes to solute distribution. This study demonstrates the basic processes by which substances are distributed in the cochlea and provides a foundation to understand how other applied substances will be distributed in the ear.

Animals↗

PubMed2000

Blood-perilymph barrier and ototoxicity: an in vivo study in the rat.

Cisplatin and gentamicin are two ototoxicants that are supposed to be transported by the paracellar route, i.e. via cellular junctions, to the perilymphatic compartment. This study was initiated to test the hypothesis that susceptive variation of individuals to ototoxic drugs may be explained by variability in transport properties. The transport of radioactive mannitol through the blood-perilymph barrier was correlated in vivo with the acute effect of cisplatin and gentamicin on auditory function. Transport of radioactive mannitol across the blood-perilymph barrier was monitored by sampling of scala vestibuli perilymph at 60 and 120 min after an intravenous infusion of the tracer to nephrectomized Long Evans rats. Counting of hair cell loss was performed in the animals receiving 16 mg/kg body weight cisplatin. The transport of radioactive mannitol across the blood-perilymph barrier did not correlate with the ototoxic effect of cisplatin, evaluated as changes in the auditory-evoked brainstem response thresholds or loss of outer hair cells. The results provide evidence that the barrier function is not involved in the interindividual variability of the ototoxic effect of cisplatin. Furthermore, it can be postulated that neither cisplatin nor gentamicin induce a disruption of endothelial cell junction stability in the inner ear.

Animals↗

PubMed2003

In vivo observation of dynamic perilymph formation using 4.7 T MRI with gadolinium as a tracer.

OBJECTIVE: To investigate the pharmacokinetics of gadolinium in the perilymphatic fluid spaces of the cochlea in vivo using high-resolution MRI to obtain information concerning perilymph formation. MATERIAL AND METHODS: A Bruker Biospec Avance 47/40 experimental MRI system with a magnetic field strength of 4.7 T was used. Anesthetized pigmented guinea pigs were injected with the contrast agent Gd-diethylenetriaminepentaacetic acid-bismethylamide and placed in the magnet. The signal intensity of Gd in the tissues was used as a biomarker for dynamic changes in the perilymphatic fluid. RESULTS: The most rapid uptake of Gd in the perilymphatic fluid spaces occurred in the lower part of the modiolus, followed by the second turn of the scala tympani. Within the scala tympani, the distribution of Gd in the basal turn was significantly lower than that in the other turns. Destruction of the cochlear aqueduct was followed by an increase in Gd uptake in the perilymph instead of a reduction. CONCLUSIONS: These findings offer further evidence that the pervasive perilymphatic fluid derives from the cochlear blood supply via the cochlear glomeruli, which are in close proximity to the scala tympani within the modiolus, and the capillary in the spiral ligament. Cerebrospinal fluid communicates with perilymph via the cochlear aqueduct but is not the main source of perilymph. These findings are of relevance to the treatment of inner ear diseases, as well as to our understanding of the flow and source of perilymphatic fluid.

Animals↗

PubMed1981

Pharmacokinetics of gentamicin in perilymph and endolymph of the rat as determined by radioimmunoassay.

The kinetics of gentamicin in the inner ear fluids of the rat were studied with a sensitive radioimmunoassay. Continuous infusion over a broad range (7.5--150 micrograms/min) was used to obtain equilibrium. The lowest rate of infusion produced plasma concentrations after 45 min that were within the range of peak serum levels desirable in humans. The purity of perilymph and endolymph was ensured by measurement of sodium and potassium concentrations. The concentration of gentamicin in perilymph was linearly related to its concentration in plasma, which depended on the rate of infusion. After six days of constant infusion of gentamicin at 15 microgram/min, the concentrations in plasma, perilymph, and endolymph averaged 25.8, 5.1, and 1.2 micrograms/ml, respectively, for five of 11 rats. Gentamicin cleared from the perilymph with a half-life of 3 hr.

Animals↗

PubMed2000

Transferrin microheterogeneity in human perilymph.

OBJECTIVES/HYPOTHESIS: Assay for beta2-(asialo-) transferrin has been advocated for use in diagnosis of cerebrospinal fluid (CSF) leak or perilymphatic fistula based on the fact that it is present in these fluids but not in serum. Quantitation of the sensitivity of transferrin assays has not been reported previously. The present study was undertaken to quantify the sensitivity of a microelectrophoretic assay of beta2-transferrin and assess its potential applicability to clinical diagnosis of perilymphatic fistula. STUDY DESIGN: The initial part of the study was a prospective bench biochemistry assessment of assay sensitivity and reliability. Subsequent application of the assay was a blinded prospective clinical trial. METHODS: Transferrin is a ubiquitous monomeric glycoprotein consisting of 679 amino acids, two iron-binding sites, and two N-linked complex glycan chains. The N-glycan chains branch in variable degree, carrying from zero to eight sialic acid residues. This variation in sialylation has been termed "microheterogeneity." When both iron-binding sites are saturated, the microheterogeneity of sialic acid content results in isoelectric points ranging from pH 5 to pH 6. Thus these nine transferrin variants can be distinguished by isoelectric focusing. Samples of transferrin solution or body fluids (serum, CSF, and perilymph) were incubated in iron-loading buffer to saturate both iron-binding sites and then subjected to isoelectric focusing (IEF). The separated proteins were immunoprecipitated in the IEF gel and silver stained for visualization. Serial dilutions of pure transferrin solution were used to determine assay sensitivity. Neuraminidase was used to digest sialic acid side chains from pure transferrin in solution, and the reaction product was used as a reference standard for comparison to assay of unknown fluids. Patient inner ear fluid samples obtained during stapedectomy or cochlear implantation were used to assess clinical applicability of the assay. RESULTS: This microelectrophoretic technique, using only 0.3 microL of iron-loaded sample, was able to consistently detect less than 250 pg of transferrin in solution and separate the different sialylation variants based on their isoelectric points. Assay of patient serum samples clearly demonstrated transferrin microheterogeneity. Assay of CSF consistently showed the predicted beta2-(asialo-) transferrin band. Assay of inner ear fluid samples also demonstrated transferrin microheterogeneity. However, no inner ear fluid samples had detectable levels of beta2-transferrin. Presumably, perilymph sample dilution during iron loading and by admixture with serum, local anesthetic, or middle ear secretions lowered the beta2-transferrin concentration below the detection limen of the assay. CONCLUSIONS: Microelectrophoretic assay of iron-loaded transferrin can detect as little as 250 pg of protein and can identify microheterogeneity in serum, CSF, and perilymph. However, dilutional effects of sample handling and preparation can lower the beta2-transferrin concentration of inner ear fluid samples below the detection limen of the assay. Thus, depending on the relative amounts of serum and perilymph (or CSF) in a mixed sample, electrophoretic separation of transferrin variants may not be diagnostic.

Fistula↗

PubMed2004

Detection of herpesvirus DNAs in perilymph obtained from patients with sensorineural hearing loss by real-time polymerase chain reaction.

OBJECTIVES/HYPOTHESIS: Perilymph and peripheral blood mononuclear cells (PBMCs) from patients with bilateral severe sensorineural hearing loss (SNHL) were evaluated for the presence of DNA from cytomegalovirus (CMV), herpes simplex virus (HSV), and human herpesvirus (HHV)6. STUDY DESIGN: A prospective clinical study. METHODS: The subjects were 14 patients who underwent cochlear implantation and 1 patient who underwent gentamicin injection in the inner ear. We attempted to detect viral DNA from perilymph and PBMCs by real-time polymerase chain reaction (rtPCR). RESULTS: CMV DNA was detected in two perilymph specimens obtained from patients who were diagnosed as congenitally symptomatic CMV infection, although no CMV DNA was detected in PBMCs. Neither HSV DNA nor HHV6 DNA was detected in any other perilymph specimens. CMV DNA was detected in three PBMC samples, HSV DNA was detected in two samples, and HHV6 DNA was detected in six samples. CONCLUSION: CMV may persistently infect the inner ear of patients with congenital CMV infection, and rtPCR analysis may prove to be a valuable tool for investigating the etiology of SNHL.

Adult↗