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Biomedical subjects

K E Rarey

Publications and source records attributed to K E Rarey.

At least 55 records · Page 3Linked to original sources
PubMed1991

Response of the stria vascularis to corticosteroids.

Structural changes in the cellular architecture of the stria vascularis in adrenalectomized rats were quantitated by stereological methods after the administration of either aldosterone or dexamethasone. The volume densities of the differing strial components from steroid-administered animals were determined to approximate those of sham-adrenalectomized animals in general. The increased volume density of intercellular space as was observed following adrenalectomy, however, was only restored after the administration of aldosterone. These data correlate a recovery of the cellular architecture of the stria vascularis in adrenalectomized animals with the restoration of endogenous levels of adrenal steroids. These findings provide further information with regard to the effects of varying serum levels of corticosteroids on inner ear morphology.

Adrenal Insufficiency↗
PubMed1990

Quantitative assessment of the rat stria vascularis.

Stria vascularis tissues from standardized regions in the basal, middle and apical turns of the rat cochlear duct were assessed quantitatively. Strial width, number of marginal cells across the strial width, radial area, as well as the volume density of the different components of the stria vascularis were determined for each standardized region. Strial width, number of marginal cells across the strial width and the radial area were greatest in the basal region and least in the apical region of the cochlea. The volume density of intermediate cells and capillary space was statistically unchanged in the three examined regions of the stria vascularis. However, the volume density of marginal cells and that of basal cells were different between regions. The volume density of marginal cells was highest in the basal turn while the volume density of basal cells was greatest in the apical turn. An objective assessment of the response of the stria vascularis to environmental conditions can be made by kant of its cellular architecture, providing a means to compare the effects of various agents between animal models used to study human inner ear dysfunction.

Animals↗
PubMed1990

Morphometry of ampullar dark cells.

The morphologic characteristics of rat ampullar dark cells were analyzed quantitatively. Four parameters were measured: cell area per micron baseline length, membrane surface density, volume density of intercellular space, and volume density of vacuoles. No statistically significant difference was observed for any parameter, either between dark cell regions of the superior, lateral, and posterior ampullae or between different regions of dark cells within a given ampulla. The membrane surface density of the ampullar dark cells was similar to that reported for principal cells of the cortical collecting duct in the kidney. The volume density of the intercellular spaces of the dark cells was very constant, unlike that reported for epithelia involved in isotonic fluid transport. Vacuoles were found to comprise only a small portion of protoplasm in the dark cells. This new morphometry provides a basis on which to examine the response of ampullar dark cells to differing experimental conditions.

Animals↗
PubMed1990

Free amino acid analysis of guinea pig perilymph: a possible clinical assay for the PLF enigma?

Controversy prevails regarding the accuracy of the clinical diagnosis of perilymphatic fistula (PLF). The diagnosis of PLF has been based on the subjective evaluation of vestibular function tests and the intraoperative macroscopic visualization of "clear fluid" from the oval/round windows at the time of exploratory tympanotomy. However, the subjective visual characterization of PLF varies among observing surgeons. Furthermore, perilymph can be "contaminated" with serum, blood, cerebrospinal fluid (CSF), and local anesthesia. This article presents a scientific biochemical microassay for the free amino acid profile of perilymph. Microaliquots of uncontaminated perilymph were sampled from the bilateral round windows (scala tympani) of 20 guinea pigs and analyzed for 19 free amino acid concentrations (FAAC) by high-performance liquid chromatography (HPLC). These samples were compared with the FAAC of guinea pig serum samples. Perfect predictor value ranges were nonoverlapping for 12 of 19 free amino acids in perilymph vs. plasma. Amino acid microassay of middle ear fluid for verification of "true" perilymph vs. nonperilymph fluids by the identification of nonoverlapping FAA markers may allow scientific verification of the existence of PLF in "suspected" patients.

Amino Acids↗
PubMed1989

Decreased adenosine triphosphatase activity in the absence of adrenocorticosteroids.

Changes in adenosine triphosphatase activity and cellular integrity of rat inner-ear tissues were observed after removal of adrenal steroids via bilateral adrenalectomy. Statistical significance of total and magnesium ion-dependent adenosine triphosphatase activities of the stria vascularis, spiral ligament, and ampullar dark cells from adrenalectomized animals was detected when compared with those of controls as demonstrated by fluorometric microassay. Although there was a similar reduction of activity in utricular dark-cell tissues, no significant difference between the treated and control animals was observed. An increase of intercellular space and a decrease in basolateral infoldings of cells of the stria vascularis and dark cell regions of adrenalectomized animals were observed. Such data collectively provide indirect evidence that adrenal steroids are involved in the cellular regulation of inner-ear tissues that are concerned with fluid and ionic microhomeostasis.

Adenosine Triphosphatases↗
PubMed1989

Presence of type I and type II/IB receptors for adrenocorticosteroid hormones in the inner ear.

Aldosterone-Type I and dexamethasone-Type II/IB receptor complexes were identified in cytosol prepared from both cochlear and vestibular tissue samples. The specific binding capacity of Type I receptors in the cochlear tissues was approximately equal to that in the vestibular tissues. Likewise, the binding capacity of Type II/IB receptors in the cochlea was approximately equal to that in the vestibular endorgans. Based on the total specific binding measured with dexamethasone, the Type II/IB receptors appeared to outnumber the Type I receptors in cochlear and vestibular tissues by a factor of approximately 2.6; however, when adjustments were made for the probable cross-binding of dexamethasone to Type I receptors, these ratios were decreased to approximately 1.6. The existence of protein receptors for adrenocorticosteroid hormones demonstrated in the present study clearly suggests a mechanism whereby such hormones may directly regulate fluid and ionic gradients in the inner ear.

Aldosterone↗
PubMed1989

Establishment of inner ear epithelial cell culture: isolation, growth and characterization.

Select epithelial regions of the bovine inner ear were established and maintained in cell culture. Marginal cells from the stria vascularis and dark cells from the posterior wall of the utricle were isolated, dissociated and placed in culture medium. Within 24 h, cellular islands of hexagonal-shaped, epithelial-like cells from both the stria vascularis and posterior utricular wall were readily identifiable by inverted light microscopy. Ultrastructural examination of both the cultured stria marginal cells and utricular dark cells revealed that both cell types had numerous microvilli on their apical surfaces and interdigitating infoldings of their basolateral surfaces. Apical tight junctional complexes were present between apposing cells. These findings demonstrate that inner ear bovine epithelial cells can be successfully isolated and maintained in culture, and that such cells retain certain of their in vivo morphological characteristics.

Animals↗
PubMed1988

Margins of safety with transantral orbital decompression.

This study involves evaluation of the surgical limits of transantral orbital apex decompression (as described by Ogura) by performing the operation on 17 cadaveric half-heads. Measurements were then made of the proximity of bone removal to several vital structures including the optic nerve, carotid artery siphon, cavernous sinus, and frontal lobe dura. Entrance into the sphenoid sinus was found to be routine. Adequate decompression requires maximum removal of bone at the orbital apex and incision of the periorbita without damage to the adjacent vital structures. This requires; 1. knowledge of ethmoid and sphenoid sinus anatomy and recognition of anatomic variations, 2. removal of bone under direct visualization, and 3. incisions of the periorbita be made most posteriorly first to prevent prolapse of orbital fat anteriorly which obscures vision of the critical orbital apex periorbita.

Adult↗
PubMed1987

Comparative ototoxicity of gentamicin in the guinea pig and two strains of rats.

Gentamicin ototoxicity and nephrotoxicity were compared in two strains of rats, Sprague-Dawley and Fisher-344, and in the Hartley albino guinea pig. Treatment groups consisting of 8 male rats of each strain and four male guinea pigs were dosed subcutaneously for 14 days with either 80 or 100 mg/kg of gentamicin sulfate in saline. Brainstem auditory evoked response (BAER) thresholds were recorded from each animal in each group on day 11 post-administration. Blood urea-nitrogen and serum creatinine were measured in blood obtained on day 11 post-administration as measures of nephrotoxicity. Kidney weight/body weight ratios were also determined. Loss of sensory hair cells was observed in the basal region of the organ of Corti from all animals treated with 100 mg/kg of gentamicin. The hair cell loss and BAER threshold elevations were greatest in the guinea pigs. Fisher-344 rats showed more extensive hair loss and greater BAER threshold elevations than Sprague-Dawley rats. The Fisher-344 rats exhibited increased blood urea-nitrogen and kidney weight/body weight ratios. Sprague-Dawleys did not suffer any nephrotoxic effects. These data indicate that the Fisher-344 rat is useful animal in which to study aminoglycoside ototoxicity as it exhibits both functional and morphological changes after gentamicin administration.

Animals↗
PubMed1987

Response of epithelial cells of the choroid plexus in the ferret model for Reye's syndrome.

The structural integrity of epithelial cells of the lateral choroid plexus tissues from the ferret model for Reye's syndrome was examined by transmission electron microscopy after the animals were inoculated intranasally with influenza B, were administered aspirin, and/or were fed an arginine deficient diet singly and in combination. No cellular alteration in the choroidal epithelium was caused by influenza B nor by aspirin, however, the synthetic diet produced random intercellular edema. The structural integrity of choroidal epithelial cells appeared intact after ferrets were infected with influenza B and were given aspirin in combination. Cellular changes were seen, however, after each of these agents was combined with the presentation of the arginine-deficient diet. Intracytoplasmic vacuoles were observed in tissues of the choroid plexus from animals inoculated with influenza B and fed the arginine-deficient diet. Both intercellular vacuolization and intercellular edema were seen in the choroidal epithelia after ferrets were administered aspirin and were fed the synthetic diet. Such cellular changes observed in the choroidal epithelia in response to the paired presentation of these agents were not as severe as those seen in the choroid plexuses of animals in which all three agents were given in combination. These results support the hypothesis that metabolic events that occur after the administration of these agents collectively impact on epithelial cells of the choroid plexus.

Animals↗
PubMed1986

Ototoxicity of cisplatin vs. platinum analogs CBDCA (JM-8) and CHIP (JM-9).

Cis-diamminedichloroplatinum (cisplatin), a divalent platinum compound and cell-cycle nonspecific chemotherapeutic agent, produces a permanent high-frequency sensorineural hearing loss and a dose-related cumulative renal insufficiency with tubular necrosis and interstitial nephritis. Synthetic platinum analogs are presently being tested to identify an analog with greater antitumor activity, but less ototoxicity and nephrotoxicity than cisplatin. The objectives of this study were to analyze the potential cochlear and nephrotoxic effects of two synthetic platinum analogs presently in phases I and II of clinical trials, CBDCA [JM-8 or cis-diammine, 1,1-cyclobutane dicarboxylato (2)-0,0(1)-platinum (NSC-241240)] and CHIP [JM-9 or cis-dichloro-trans-dihydroxybisisopropylamine platinum IV (NSC-256927)]. Cytocochleography, auditory brain-stem evoked response (ABR), double-blind light microscopy of renal tissues, and gamma emission analysis of 195mpt localization in viscera and inner ear were employed in the evaluation of cisplatin and platinum analogs (JM-8 and JM-9) in adult guinea pigs. Final results indicate that the investigational chemotherapeutic analogs CBDCA (JM-8) and CHIP (JM-9) do not produce the ototoxicity and nephrotoxicity characteristic of cisplatin. Furthermore, these findings demonstrate 195mpt localization in the vestibular labyrinth and confirm previous platinum distribution studies in the organ of Corti and stria vascularis tissues.

Animals↗
PubMed1986

Vestibular morphological analysis of the effects of cisplatin vs. platinum analogs, CBDCA (JM-8) and CHIP (JM-9).

Synthetic second generation chemotherapeutic platinum analogs are presently being tested to identify an analog with greater antitumor activity, but less ototoxicity and nephrotoxicity than cisplatin. The objective of this study was to analyze potential vestibular effects of cisplatin and of the two platinum analogs, CBDCA (cis-diammine 1,1-cyclobutane dicarboxylato [2]-0,0(1) platinum or JM-8) and CHIP (cis-dichlorotrans-dihydroxy-bis(isopropylamine) platinum [IV] or JM-9) using scanning and transmission electron microscopy of vestibular neuroepithelium from the albino guinea pig. Vestibular neuroepithelial damage was not demonstrated in either cisplatin- or the analog-treated animals when administered at equitoxic doses.

Animals↗
PubMed1985

The ferret as a model for inner ear research.

Viral infections have long been suspected to be causative agents in a number of inner ear dysfunctions. With few exceptions, the virus has not been demonstrated as the direct agent leading to hearing loss and/or vertigo. Selective inner ear changes have been observed recently in sensory and nonsensory epithelial cells in the ferret model for Reye's syndrome after intranasal inoculation with influenza B combined with aspirin administration and the creation of an arginine deficiency. Such findings suggest that these agents act synergistically on the inner ear, particularly on cells that are metabolically active, and that the ferret may now be a useful model to examine the role of certain upper respiratory tract viruses implicated in inner ear disorders, singly and in combination with other agents that may cause metabolic alterations.

Animals↗
PubMed1984

Altered auditory brainstem evoked responses in the ferret model for Reye's syndrome.

The effects of influenza B, aspirin and hyperammonemia on the functional integrity of the cochlea were examined using the ferret model for Reye's syndrome. Auditory brainstem evoked responses (ABR) were recorded from treated ferrets and compared to those recorded from controls. Delayed latencies of all waves, as well as increased I-IV Interwave latencies were observed in recordings from treated ferrets. Importantly, the latencies of Wave I, nerve generator potential from the eighth nerve, and Wave IV, response potential from the brainstem nuclei, increased on Days 3 and 5 of the study. However, recorded ABR from treated ferrets on Day 10 showed that while the latencies of Wave IV were approximate to those of controls, Wave I remained delayed. These results suggest that systemic effects of influenza B, aspirin and hyperammonemia may lead acutely to both peripheral and central auditory dysfunction, and that the functional integrity of the central auditory system may recover more quickly than that of the peripheral system. Furthermore, these results suggest that such effects may lead to acute transient hearing impairment in patients with Reye's syndrome.

Ammonia↗
PubMed1984

Inner ear anomalies in Waardenburg's syndrome associated with Hirschsprung's disease.

Congenital inner ear anomalies are reported in temporal bones of a 22-month-old boy with Waardenburg's syndrome and Hirschsprung's disease. Although no changes in the central auditory pathway were identified, peripheral lesions of the cochlear and vestibular membranous labyrinth were observed. Bilateral atrophy of the organ of Corti and stria, and a sparsity of spiral ganglion cells were observed in the cochlea. Degeneration of the vestibular end organs, including a loss of Scarpa's ganglion cells, was also seen. This is the first report of temporal bone histopathology associated with Waardenburg's syndrome and Hirschsprung's disease. The pathoembryology of these inner ear anomalies associated with aganglionosis of the colon supports the hypothesis that Waardenburg's syndrome and Hirschsprung's disease are hereditary defects of neural crest cells.

Abnormalities, Multiple↗
PubMed1983

Brain microvessel endothelial cells in tissue culture: a model for study of blood-brain barrier permeability.

Endothelial cells were prepared from bovine microvessels and grown in tissue culture. They contained factor VIII/von Willebrand antigen, the most specific market available for determination of the endothelial origin of cells in culture. The cultured cells formed complex tight junctions and contained few pinocytotic vessels. These properties are responsible for formation of the blood-brain barrier in vivo. When monolayers of the endothelial cells were exposed briefly to a calcium-free solution or treated with 1.6 M arabinose, distinctive morphological changes occurred in the intercellular contacts. In either case, a normal structure was reestablished following return to control medium. To assess the effect of these treatments on transcellular permeability, we measured the movement of sucrose labeled with carbon 14 across a monolayer of endothelial cells cultured on a collagen-coated nylon mesh. Removal of external calcium increased the rate of sucrose movement by 120%; the arabinose treatment increased transcellular flux by 40%.

Animals↗
PubMed1983

Inner ear pathology associated with Reye's syndrome.

Severe pathological changes were observed in the inner ear tissues of a 2-month-old patient who died of Reye's syndrome after 5 days of hospitalization. In the organ of Corti, the inner hair cells appeared to be more severely damaged than the outer hair cells. Various degrees of degeneration were observed in all non-sensory epithelial cells lining the cochlear duct. In most turns of the cochlear duct, Reissner's membrane was ruptured and/or collapsed onto the organ of Corti. Likewise, both sensory and non-sensory cells of the vestibular end organs were markedly degenerated. These observations suggest that the inner ear tissues are acutely affected in patients with Reye's syndrome, and that the changes may cause impairment of hearing and/or equilibrium in patients who recover.

Acoustic Maculae↗