Biomedical subjects

W J ten Cate

Publications and source records attributed to W J ten Cate.

At least 19 recordsLinked to original sources

PubMed2000

In vitro effects of hydrogen peroxide on the cochlear neurosensory epithelium of the guinea pig.

Reactive oxygen species (ROS) have been postulated to be involved in drug ototoxicity and noise-induced hearing loss. Hydrogen peroxide (H(2)O(2))-induced cell damage in the inner ear was investigated using the neurosensory epithelium of a guinea pig cochlea. Hair cells and supporting cells of the epithelium incubated in Hanks' balanced salt solution were viable up to 6 h. After 2 h of treatment with 0.2 mM H(2)O(2) about 85% of the outer hair cells lost their viability. In contrast inner hair cells slowly began to die after 2 h of H(2)O(2) treatment. The Deiters cells and Hensen cells did not show any signs of damage in the presence of H(2)O(2). Nifedipine, a calcium channel blocker, Quin-2 AM, an intracellular calcium chelator, and 2,2'-dipyridyl, a membrane-permeable iron chelator, all provided partial protection against H(2)O(2)-induced outer hair cell death. The combination of both chelators showed an additional protective effect. The antioxidants N-acetylcysteine and glutathione-monoethyl ester completely protected against H(2)O(2) damage. These results suggest that calcium, iron, and thiol homeostasis play a crucial role in hair cell death caused by H(2)O(2).

2,2'-Dipyridyl↗

PubMed2000

[Immunohistochemical detection of humoral autoantibodies in patients with hearing loss in the last hearing ear].

BACKGROUND: An autoimmune etiology similar to the sympathetic ophthalmia has been discussed for sensorineural hearing loss on the last hearing ear following deafness in the first ear. In sympathetic cochleolabyrinthitis inner ear proteins are thought to be released after laterobasal fracture, which may induce an autoimmune process in the last hearing ear. Animal models have failed to clearly demonstrate the location of the target in the labyrinth, attacked by immunologic processes. Furthermore, it is unclear whether the humoral or cellular pathway is initiating this process. METHODS AND PATIENTS: Serum was acquired from 15 patients with traumatic or post-inflammatory unilateral deafness and slowly progressive or sudden sensorineural hearing loss on the last hearing ear. Deparaffinized sections of rat temporal bones were incubated with patient serum and subjected to immunohistochemical examination. RESULTS: A specific but heterogeneous binding pattern of the labyrinth was found in 14 of 15 patients. CONCLUSION: Our results indicate different autoantibodies in the patient serum, which may be the cause of the hearing loss. Therefore, in patients with sensorineural hearing loss on the last hearing ear, we recommend a therapeutic trial with corticosteroids.

Adrenal Cortex Hormones↗

PubMed1999

Localization of laminin isoforms in the guinea pig cochlea.

OBJECTIVE: To elucidate the pathogenesis of inner ear disorders by examining the distribution of a major component of basement membranes, the glycoprotein laminin. STUDY DESIGN: Animal model. METHODS: Adult guinea pig cochleae were fixed with methanol and sectioned. Sections were examined for the presence of laminins alpha2, alpha5, beta1, and gamma1 using immunohistochemistry. RESULTS: Laminins alpha2, alpha5, and beta1 were not detected. Laminin gamma1 was found in the limbus, spiral ligament, and stria vascularis. CONCLUSIONS: Anti-laminin antibodies have been found in patients with inner ear disorders. Laminin gamma1 demonstrates specific staining at multiple sites in the guinea pig cochlea. These structures may be targets of antibodies causing sensorineural hearing loss.

Adult↗

PubMed1998

Expression of the gap-junction connexins 26 and 30 in the rat cochlea.

Gap junction channels which are responsible for direct intercellular communication are composed of connexin proteins. Different connexins are distributed in a tissue-specific manner. Up to now only connexin26 has been identified to be widely expressed in the inner ear. In order to investigate the role of additional gap junction proteins, the expression of connexin30 and 43 was investigated in the rat cochlea. Connexin26 and connexin30 were both expressed in the spiral limbus, the spiral ligament, the stria vascularis and between supporting cells of the organ of Corti. Double-labeling experiments suggest that both connexins are partly colocalized between cells. Weak staining of connexin43 could only be detected in the stria vascularis, the spiral ligament and between organ of Corti supporting cells. The corresponding transcripts for connexin26, 30 and 43 could be detected by Northern blot analysis. The expression of different gap junction channels in the cochlea suggests functional diversity. Gap junctions in the inner ear may control ion concentrations of cochlear fluids or act as conduits through which glucose and other metabolites diffuse.

Animals↗

PubMed1998

[Hearing loss caused by high dose carboplatin therapy].

BACKGROUND: Carboplatin is regarded as a non-ototoxic or low-grade ototoxic chemotherapeutic agent. METHOD: We report on three patients with a recurrence of testicular cancer after cisplatin chemotherapy who suffered hearing loss after subsequent high-dose carboplatin therapy. RESULTS: Audiometry demonstrated carboplatin-induced hearing loss primarily in the mid-range and high frequencies up to 45 dB at 3 kHz and up to 55 dB at 8 kHz. In two of three patients, transitory-evoked otoacoustic emissions were absent after carboplatin therapy. CONCLUSION: Following first-line cisplatin chemotherapy, salvage treatment with high-dose carboplatin can generate hearing loss in the middle and high frequencies.

Adult↗

PubMed1998

[Case report of epithelioid hemangioendothelioma of the frontal region metastatic to the parotid gland].

BACKGROUND: The epithelioid hemangioendothelioma is a soft tissue tumor of vascular origin. Typical localisations are subcutis, cutis, liver, lungs and bones. It has been described in 1982 by Weiss and Enzinger as a separate tumor entity. Due to the unpredictable biological behaviour of the tumor, a borderline malignancy is assumed. CASE REPORT: We report on the case of a 44-year old woman with a metastasising epithelioid hemangioendothelioma in the head and neck area. The primary tumor was located in the subcutis of the left forehead. Due to local recurrences surgical treatment was performed three times after the initial removal in 1993. At the time of the last local recurrence in 1996, a tumor in the left parotid gland was diagnosed and was the reason for a lateral parotidectomy. Pathohistologically, a metastasis of the epithelioid hemangioendothelioma was found. Postoperative radiotherapy was performed and no recurrence occurred until now (22 months follow-up). CONCLUSION: Metastatic epithelioid hemangioendotheliomas are rarely found in the head and neck area. Literature has not yet reported on metastasis formation in the parotid gland. The case illustrates the potentially malignant behaviour of epithelioid hemangioendotheliomas. Hence, therapy should consist of a combination of radical tumor removal and post-operative radiotherapy.

Adult↗

PubMed1997

Postnatal expression of the alpha-thyroid hormone receptor in the rat cochlea.

Thyroid hormone receptors belong to the superfamily of nuclear receptors which are expressed in many tissues. Reduced levels of thyroid hormones in acquired or congenital hypothyroidism can lead to hearing loss which may be irreversible. In this study we investigated immunohistochemically the postnatal distribution of the triiodothyronine alpha receptor in the rat cochlea. Cell regions of high sensitivity towards thyroid hormones should have a high density of thyroid hormone receptors. Strong immunoreactivity for the alpha-thyroid hormone receptor was observed in spiral ganglion cells as well as inner and outer hair cells of the cochlea. Staining could be detected during all stages investigated from the first postnatal day up to day 30 and exhibited mainly a nuclear pattern. These observations suggest that spiral ganglion cells and hair cells are target regions of thyroid hormones in the adult and developing cochlea. Thyroid hormones could thus play an important role in the maturation of the inner ear.

Animals↗

PubMed1997

Development of 11 beta-hydroxysteroid dehydrogenase expression in the rat cochlea.

11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) catalyzes the transformation of active glucocorticoid (GC) steroids to inactive 11-oxosteroids, as well as the reverse reaction. 11 beta-HSD was previously demonstrated specifically in the spiral ligament of the lateral cochlear wall where it was co-localized with adrenal steroid receptors. These findings imply that 11 beta-HSD regulates binding of corticoids to their inner ear receptors. The GC receptor expression initially occurs around the critical maturation period of the cochlear duct. 11 beta-HSD, which is an integral part of the cochlear steroid receptor system, could indirectly affect glucocorticoid-mediated induction processes. In this study the expression of 11 beta-HSD was studied in the postnatal rat cochlea from the 3rd to 30th postnatal day. Bouin's fixed, paraffin-embedded cochlear sections were processed for immunocytochemical detection of 11 beta-HSD using polyclonal antibodies against 11 beta-HSD. 11 beta-HSD expression appeared at the 12th postnatal day at low levels in spiral ligament tissues. From the 15th postnatal day, 11 beta-HSD expression was stronger and similar to that of the adult cochlea. No additional inner ear tissue region expressed 11 beta-HSD enzyme during the observed period. 11 beta-HSD expression coincides with the onset of functional maturity of the rat cochlear duct. The expression of 11 beta-HSD is preceded by the expression of GC receptors which appeared at the 7th postnatal day in the rat cochlea. These results further suggest an integrative role of the cochlear steroid receptor system in the homeostasis and functional maturation of the cochlea.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1996

[Diagnosis and therapy of thyroid tissue of the base of the tongue].

Lingual thyroid tissue is the most frequent ectopic location of the thyroid gland, although its clinical incidence is low with 1 in 100,000 cases occurring. We describe a 25-year-old woman who presented with dysphagia due to lingual thyroid tissue. Suppressive hormone therapy did not have a significant effect. Surgical therapy was used when obstructive symptoms increased. The lingual thyroid was resected partially while the remaining gland was transposed into a lateral submental region. Diagnostic procedures using such imaging techniques as scintigraphy, ultrasound, computed tomography and magnetic resonance imaging and therapeutic options are discussed.

Adult↗

PubMed1995

Effect of stress on cochlear glucocorticoid protein: acoustic stress.

Levels of glucocorticoid (GR) receptor protein were determined by a quantitative enzyme-linked immunosorbent assay (ELISA) technique in inner ear tissue of rats exposed daily to 85 dB SPL white noise for 4 hours on 3 consecutive days. GR levels in spiral ligament and organ of Corti tissues were detected using a monoclonal antibody to the GR receptor, BuGR2. A non-significant 13% decrease in GR levels of spiral ligament tissues was observed in the noise exposed animals relative to untreated animals. A statistically significant decrease of 27% in GR protein levels was seen in the organ of Corti region (P < 0.03), however. There was a concomitant increase of serum corticosterone levels (P < 0.03) in noise exposed animals as opposed to those of controls. These results indicate a tissue specific response of GR receptor to acoustic stress. Inner ear GR protein therefore may be a useful marker in determining the effect of stress on the inner ear. Finally, such data may be applicable to support the hypothesis that stress is an etiological agent in Ménière's disease.

Acoustic Stimulation↗

PubMed1995

Glucocorticoid receptor expression in the postnatal rat cochlea.

The glucocorticoid receptor (GR) expression in the neonatal rat cochlea was investigated by utilization of a polyclonal antibody against GR, the immunoreactivity of which exhibited a distinct, age-dependent developmental pattern in tissues of the spiral ligament (SL). Immunostaining of GR appeared initially at the 7th postnatal day (PND), increased rapidly between the 14th and 21st PND, and reached adult-like expression levels by the 21st PND. Less pronounced, developmentally regulated expression patterns of GR were observed in cells of the spiral limbus (SLi), spiral ganglion (SG), organ of Corti (OC), and cochlear nerve (CN). For example, high expression levels of GR were observed in the SLi, SG and OC at 3 PND; subsequently, GR immunoreactivity levels decreased from 7 to 14 PND, and then GR immunoreactivity intensified in these regions by 21 PND. No remarkable changes in GR expression were observed in stria vascularis (SV). These data indicate that GR expression in the inner ear is tissue and age-specific, and that GR expression parallels both Na,K-ATPase expression and endocochlear potential development.

Aging↗

PubMed1994

Effects of low-sodium, high-potassium dietary intake on cochlear lateral wall Na+,K(+)-ATPase.

The effect of a low Na+, high K+ diet on Na+,K(+)-ATPase levels in cochlear lateral wall tissues was investigated in laboratory rats by using an enzyme-linked immunosorbent assay. The low Na+, high K+ diet induced high aldosterone plasma levels in the animals as well as changes in plasma cation levels. Animals that received a low Na+, high K+ diet demonstrated a statistically significant (97%) increase in Na+,K(+)-ATPase levels in the stria vascularis when compared to animals that received a control diet. This increase in strial Na+,K(+)-ATPase levels was blocked only 70% by administration of the aldosterone antagonist, spironolactone. Findings therefore indicate that strial Na+,K(+)-ATPase may be modulated by both aldosterone and Na+,K+ plasma levels. Na+,K(+)-ATPase levels in the spiral ligament were not affected by the experimental treatment. These findings suggest that spiral ligament Na+,K(+)-ATPase levels may be regulated by factors other than aldosterone and Na+,K+ plasma levels. This study provides further insight into the mechanisms of the beneficial effects of salt restriction and potassium loading in patients with Méniére's disease.

Aldosterone↗

PubMed1994

Expression of Na+,K(+)-ATPase alpha 1 subunit mRNA in the developing rat cochlea.

The distribution of Na+,K(+)-ATPase alpha 1 subunit mRNA was identified using in situ hybridization in the developing rat cochlea. The expression of alpha 1 subunit mRNA in stria vascularis (SV) was observed in all time points studied, 1 to 30 postnatal day (pnd) rats. The adult expression level was attained between 11 to 14 pnd. Surprisingly, alpha 1 subunit mRNA in spiral ligament (SL) and spiral limbus (SLi) was expressed in a more distinct time-dependent manner. At 7 pnd, the alpha 1 subunit mRNA expression was observed initially in the tissues of the SL. At 11 pnd, alpha 1 subunit expression appeared in SLi. Between 11 and 14 pnd, an adult-like pattern of Na+,K(+)-ATPase alpha 1 subunit mRNA expression was attained in the SL and SLi. These data suggest that the expression of Na+,K(+)-ATPase alpha 1 subunit mRNA in these areas are closely related to the development of the rat EP, as its expression in the stria vascularis.

Animals↗

PubMed1994

Na,K-ATPase alpha and beta subunit isoform distribution in the rat cochlear and vestibular tissues.

The distribution of five Na,K-ATPase subunit isoforms (alpha 1, alpha 2, alpha 3, beta 1 and beta 2) in rat cochlear and vestibular tissues was determined by immunocytochemical techniques using subunit isoform specific polyclonal antibodies. The expression of Na,K-ATPase alpha and beta subunit isoforms varied among different cell regions of the inner ear. The alpha 1 subunit isoform was more extensively distributed in all inner ear tissues than the alpha 2 or alpha 3 subunit isoforms. The beta 1 subunit isoform was distributed primarily in spiral ligament and inner hair cells of the cochlea, and in crista ampullaris and macula of the saccule. The beta 2 subunit isoform was most abundant in the stria vascularis, dark cells of the ampullae and utricle. The alpha 1 beta 1 subunit combination of Na,K-ATPase was most commonly found in the spiral ligament, while the alpha 1 beta 2 combination was most abundant in the stria vascularis. Similarly, alpha 1 beta 2 was confined more to the dark cells of the ampullae and utricle. The alpha 3 beta 1 subunit combination of Na,K-ATPase was identified in the inner hair cells of the cochlea and the sensory regions of the vestibular end organs. These observations may reflect functional diversity of Na,K-ATPase in the individual inner ear regions and may provide insight into the differences between fluid and ion transport in the inner ear and that of other transporting tissues. Overall, the distribution pattern further indicates that the different isoform combinations have specific roles.

Animals↗

PubMed1994

Density of marginal cell basolateral membranes in basal, middle, and apical turns of the rat cochlea.

The Na-K-ATPase activity within stria vascularis tissues has been observed to decrease from basal to apical cochlear turns. This reduction in Na-K-ATPase activity in more apical regions of the cochlea may be accounted for, at least in part, by a lower density of Na-K-ATPase-containing basolateral membranes of the marginal cells. This study was performed to compare the surface density of marginal cell basolateral membranes in standardized basal, middle, and apical turns of the rat cochlea. Montages of transmission electron microscopic micrographs of standardized regions of the rat stria vascularis were morphometrically analyzed. Surface area of marginal cell basolateral membrane was determined per unit stria vascularis volume and per unit marginal cell volume. Results demonstrated that the surface density of marginal cell basolateral membrane per stria vascularis volume of the standardized basal region increased 20 percent compared to that of the standardized apical region (p < or = .1). Surface density of marginal cell basolateral membranes per marginal cell volume was similar in all three standardized turns. The observed longitudinal differences in surface density of marginal cell basolateral membranes per stria vascularis volume may account, in part, for the biochemical cochlear Na-K-ATPase activity gradient from base to apex.

Animals↗

PubMed1993

Dynamics of Na,K-ATPase sites in lateral cochlear wall tissues of the rat.

The objective of this study was to determine whether varying levels of either the synthetic glucocorticoid, dexamethasone, or the mineralocorticoid, aldosterone, modulate the quantity of Na,K-ATPase sites in stria vascularis and spiral ligament tissues. Surgically adrenalectomized male rats were administered different dosages of dexamethasone or aldosterone for 7 days and subsequently were sacrificed. Na,K-ATPase alpha-subunits of stria vascularis and spiral ligament homogenates were determined quantitatively by enzyme-linked immunosorbent assay, using a monoclonal antibody shown to react with lateral wall Na,K-ATPase alpha-subunit. Elevated serum levels of dexamethasone were correlated with significantly increased Na,K-ATPase alpha-subunit levels in both the stria vascularis and spiral ligament (P < 0.05). Elevated serum levels of aldosterone were correlated with increased Na,K-ATPase alpha-subunits in the stria vascularis, but not in the spiral ligament (P < 0.1). These data further indicate a positive correlation between increased serum levels of adrenal steroids and induction of Na,K-ATPase synthesis by such steroids, particularly by dexamethasone.

Adrenalectomy↗

PubMed1993

Tissue specific levels of glucocorticoid receptor within the rat inner ear.

Individual, rat inner ear tissues were isolated and processed for determination of levels of glucocorticoid (GR) receptor by an Enzyme Linked Immuno-Sorbant Assay (ELISA). Differing levels of GR receptor between seven sampled inner ear regions were measured. Levels of GR receptors in the spiral ligament tissues were found to be significantly higher compared to all other tissue samples. GR levels in the tissues of stria vascularis and organ of Corti were different from one another but both were statistically higher than those detected in the vestibular tissue samples (dark cell regions, cristae ampullares and maculae utriculi), which had the lowest GR receptor levels measured. Intermediate levels of GR receptor were found in the endolymphatic sac region. It is suggested that the varying levels of inner ear GR receptors may be indicative of differing biological responses among the given tissues, as well as differences in the magnitudes of such responses to circulating glucocorticoids.

Analysis of Variance↗

PubMed1993

Localization of glucocorticoid receptors and glucocorticoid receptor mRNAs in the rat cochlea.

The distribution of glucocorticoid (GR) receptor messenger RNAs (mRNAs) and GR receptors was studied by in situ hybridization histochemistry and immunocytochemistry, respectively. In situ hybridization histochemistry was performed with a biotin-labeled riboprobe complementary to rat GR receptor mRNA. GR receptor mRNAs were demonstrated in spiral ligament cells, spiral limbus cells, and spiral ganglion cells. GR receptor mRNAs were demonstrated neither in cells of the stria vascularis nor in cells of the organ of Corti region. With the use of a monoclonal and a polyclonal antibody, GR receptors were observed in the spiral ligament cells, stria vascularis cells, spiral limbus cells, and spiral ganglion cells by immunocytochemistry. Binding of anti-GR-receptor antibodies to a lesser extent was observed in the organ of Corti region; however, cellular distribution of the GR receptors could not be resolved with the applied techniques. These results suggest that the GR receptor is expressed differently in the heterogeneous cochlear tissues.

Animals↗