Gene expression pattern after insertion of dexamethasone-eluting electrode into the guinea pig cochlea.

A cochlear implant is an indispensable apparatus for a profound hearing loss patient. But insertion of the electrode entails a great deal of stress to the cochlea, and may cause irreversible damage to hair cells and related nerve structure. Although damage prevention effects of dexamethasone have been reported, long-term administration is difficult. In this study, we used a dexamethasone-eluting electrode in the guinea pig cochlea, and compared the gene expression after 7 days insertion with that of a normal electrode and non-surgically treated control by microarray. 40 genes were up-regulated 2-fold or more in the normal electrode group compared to the non-surgically treated group. Most of the up-regulated genes were associated with immune response and inflammation. In the dexamethasone-eluting group, compared to the normal electrode group, 7 of the 40 genes were further up-regulated, while 12 of them were down-regulated and there was a tendency to return to the non-surgical condition. 9 genes were down-regulated 2-fold or less with normal electrode insertion, and 4 of the 9 tended to return to the non-surgical condition in the dexamethasone-eluting group. These genes are certainly involved in the maintenance of the physiological functions of the cochlea. Our results indicate that the dexamethasone-eluting electrode will have an effect on the normalization of homeostasis in the cochlea.

Guanine nucleotide-binding protein 1 is one of the key molecules contributing to cancer cell radioresistance.

Standard fractionated radiotherapy for the treatment of cancer consists of daily irradiation of 2-Gy X-rays, 5 days a week for 5-8 weeks. To understand the characteristics of radioresistant cancer cells and to develop more effective radiotherapy, we established a series of novel, clinically relevant radioresistant (CRR) cells that continue to proliferate with 2-Gy X-ray exposure every 24 h for more than 30 days in vitro. We studied three human and one murine cell line, and their CRR derivatives. Guanine nucleotide-binding protein 1 (GBP1) gene expression was higher in all CRR cells than their corresponding parental cells. GBP1 knockdown by siRNA cancelled radioresistance of CRR cells in vitro and in xenotransplanted tumor tissues in nude mice. The clinical relevance of GBP1 was immunohistochemically assessed in 45 cases of head and neck cancer tissues. Patients with GBP1-positive cancer tended to show poorer response to radiotherapy. We recently reported that low dose long-term fractionated radiation concentrates cancer stem cells (CSCs). Immunofluorescence staining of GBP1 was stronger in CRR cells than in corresponding parental cells. The frequency of Oct4-positive CSCs was higher in CRR cells than in parental cells, however, was not as common as GBP1-positive cells. GBP1-positive cells were radioresistant, but radioresistant cells were not necessarily CSCs. We concluded that GBP1 overexpression is necessary for the radioresistant phenotype in CRR cells, and that targeting GBP1-positive cancer cells is a more efficient method in conquering cancer than targeting CSCs.

Inner hair cells of mice express the glutamine transporter SAT1.

Glutamate has been implicated in signal transmission between inner hair cells and afferent fibers of the organ of Corti. The inner hair cells are enriched in glutamate and the postsynaptic membranes express AMPA glutamate receptors. However, it is not known whether inner hair cells contain a mechanism for glutamate replenishment. Such a mechanism must be in place to sustain glutamate neurotransmission. Here we provide RT-PCR and immunofluorescence data indicating that system A transporter 1 (SLC38A1), which is associated with neuronal glutamine transport and synthesis of the neurotransmitters GABA and glutamate in CNS, is expressed in inner hair cells. It was previously shown that inner hair cells contain glutaminase that converts glutamine to glutamate. Thus, our finding that inner hair cells express a glutamine transporter and the key glutamine metabolizing enzyme glutaminase, provides a mechanism for glutamate replenishment and bolsters the idea that glutamate serves as a transmitter in the peripheral synapse of the auditory system.

Comparison of the diagnostic value of 3 T MRI after intratympanic injection of GBCA, electrocochleography, and the glycerol test in patients with Meniere's disease.

CONCLUSION: 3 T MRI after intratympanic injection of gadolinium-based contrast agent (GBCA) is more useful for the diagnosis of endolymphatic hydrops compared with the glycerol test and electrocochleography (ECoG). OBJECTIVE: To investigate the relationship between 3 T MRI after intratympanic injection of GBCA, the glycerol test, and ECoG in patients with Meniere's disease (MD). METHODS: A total of 20 patients with MD were evaluated. Diluted gadodiamide (a gadolinium-based contrast agent) was administered to the bilateral tympanic cavity by injection through the tympanic membrane. After 24 h, the endolymphatic hydrops was evaluated by a 3.0 T MR scanner. To investigate cochlear hydrops, the glycerol test and ECoG were carried out in all patients. RESULTS: A positive result was observed in 11 patients (55%) in the glycerol test and in 12 patients (60%) by ECoG. The incidence of positive findings when evaluating the same patients with both the glycerol test and ECoG increased to 75%. Nineteen of 20 (95%) patients showed positive results for 3 T MRI.

Loss of astrocyte polarization in the tg-ArcSwe mouse model of Alzheimer's disease.

Aquaporin-4 (AQP4) is the predominant water channel in brain and is selectively expressed in astrocytes. Astrocytic endfoot membranes exhibit tenfold higher densities of AQP4 than non-endfoot membranes, making AQP4 an excellent marker of astrocyte polarization. Loss of astrocyte polarization is known to compromise astrocytic function and to be associated with impaired water and K+ homeostasis. Here we investigate by a combination of light and electron microscopic immunocytochemistry whether amyloid deposition is associated with a loss of astrocyte polarization, using AQP4 as a marker. We used the tg-ArcSwe mouse model of Alzheimer's disease, as this model displays perivascular plaques as well as plaques confined to the neuropil. 3D reconstructions were done to establish the spatial relation between plaques and astrocytic endfeet, the latter known to contain the perivascular pool of AQP4. Changes in AQP4 expression emerge just after the appearance of the first plaques. Typically, there is a loss of AQP4 from endfoot membranes at sites of perivascular amyloid deposits, combined with an upregulation of AQP4 in the neuropil surrounding plaques. By electron microscopy it could be verified that the upregulation reflects an increased concentration of AQP4 in those delicate astrocytic processes that abound in synaptic regions. Thus, astrocytes exhibit a redistribution of AQP4 from endfoot membranes to non-endfoot membrane domains. The present data suggest that the development of amyloid deposits is associated with a loss of astrocyte polarization. The possible perturbation of water and K+ homeostasis could contribute to cognitive decline and seizure propensity in patients with Alzheimer's disease.

Electromagnetic wave propagation in rain and polarization effects.

This paper summarizes our study on microwave and millimeter-wave propagation in rain with special emphasis on the effects of polarization. Starting from a recount of our past findings, we will discuss developments with these and how they are connected with subsequent research.

Semi-quantitative evaluation of endolymphatic hydrops by bilateral intratympanic gadolinium-based contrast agent (GBCA) administration with MRI for Meniere's disease.

CONCLUSION: Bilateral intratympanic administration of a gadolinium-based contrast agent (GBCA) in MRI was successfully performed and proved to be beneficial in the semi-quantitative evaluation of endolymphatic hydrops. Such image-based diagnosis will lead to re-revaluation and reclassification of the diagnostic criteria for Meniere's disease (MD). OBJECTIVE: To visualize endolymphatic hydrops semi-quantitatively in patients with MD, by using bilateral intratympanic GBCA administration with MRI. PATIENTS AND METHODS: A total of 13 patients were evaluated, including 12 with MD and one with acute low-tone sensorineural hearing loss. Diluted gadodiamide (a kind of GBCA) was administered to the bilateral tympanic cavity by injection through the tympanic membrane. After 24 h, the endolymphatic hydrops was evaluated with a 3.0 T MR scanner. The areas enhanced by gadodiamide were measured semi-quantitatively. RESULTS: Three-dimensional, fluid-attenuated inversion recovery (3D-FLAIR) MRI showed that the gadodiamide successfully penetrated the round window membrane, entering the perilymphatic space and delineating the gadodiamide-enhanced perilymphatic and gadodiamide-negative endolymphatic spaces of the inner ear. All the patients with MD showed a reduced gadodiamide-enhanced area representing the perilymphatic space, and the quantitative ratio was 0.15 to 0.85. Furthermore, endolymphatic hydrops was also demonstrated in the patient with atypical MD who had fluctuating low frequency sensorineural hearing loss without vertigo.

Endolymphatic hydrops and therapeutic effects are visualized in 'atypical' Meniere's disease.

A 53-year-old male with fluctuating low frequency sensorineural hearing loss and tinnitus, but without vertigo, was evaluated by MRI obtained by intratympanic injection of a gadolinium-based contrast agent (GBCA) before and after the administration of isosorbide. The endolymphatic hydrops was semi-quantitatively evaluated by a 3.0-T MR scanner. For quantification, the affected side/contralateral side ratios were calculated. A gadodiamide (a kind of GBCA)-enhanced space surrounding the endolymph in the affected side with a 0.50 ratio (which may have represented endolymphatic hydrops) improved after isosorbide therapy to a 0.98 ratio. Thus, endolymphatic hydrops was demonstrated in a patient with 'atypical' Meniere's disease (MD), suggesting that at least some atypical MD may share similar etiology with, and therefore be a continuum of, MD. Also, therapeutic effects could be visualized by using MRI. Therefore, MRI-based diagnosis of MD-related disease will be a powerful tool not only because of its precision but also its usefulness for therapeutic evaluation.

Differences in the expression of genes between normal tissue and squamous cell carcinomas of head and neck using cancer-related gene cDNA microarray.

CONCLUSION: This study clearly showed the molecular characteristics of head and neck squamous cell carcinoma (HNSCC) on the basis of gene expression patterns. OBJECTIVE: cDNA microarray has recently been shown to have the ability to represent the expression patterns of large numbers of genes from a small amount of tissue, potentially enabling definition of groups of patients with similar biological behavior of cancer. Although gene expression profiling using this technique has proven helpful for predicting the prognosis in various cancers, little is known regarding HNSCC. The aim of this study was to investigate the differences in the expression of various genes between normal tissue and cancers of patients with HNSCC by cDNA microarray. PATIENTS AND METHODS: We extracted mRNA from 17 HNSCC patients and used cDNA microarray analysis to investigate the gene expression patterns. The present study was not designed to perform an inclusive search for genes but rather to focus on cancer-related genes. RESULTS: Seven independent genes were found to be up-regulated in cancer tissues: matrix metalloproteinase-1, -3, and -10, interleukin-8, cadherin 3, hexabrachion, and interferon gamma-inducible protein 10. Hyaluronic acid-binding protein 2, keratin 4, and keratin 13 were categorized as down-regulated. The hierarchical clustering and dendrogram for 17 cancer samples and 425 genes could be grouped into three clusters.

Genetic features, clinical phenotypes, and prevalence of sensorineural hearing loss associated with the 961delT mitochondrial mutation.

To examine the frequency of the 961delT mitochondrial point mutation, considered to be associated with aminoglycoside-induced hearing loss, restriction fragment length polymorphism (RFLP) analysis was performed in (1) 334 unrelated sensorineural hearing loss (SNHL) patients and (2) 56 patients with aminoglycoside antibiotic injection history. Approximately 2% of the SNHL patients had the 961delT mutation, raising the possibility of a relatively high prevalence of this mutation among hearing impaired populations. However, the following findings cast doubt on whether this mutation is truly associated with hearing loss: (1) a similar frequency found in the control subjects, (2) hearing loss that was not segregated within the families, (3) rates of heteroplasmy and aging that were not correlated with the severity of hearing loss, and (4) a low prevalence among the aminoglycoside-induced hearing loss patients (1/56=1.8%). The present analysis did not agree with the concept that the 961delT mutation causes aminoglycoside-induced hearing loss.

Clinical features of patients with GJB2 (connexin 26) mutations: severity of hearing loss is correlated with genotypes and protein expression patterns.

Mutations in the GJB2 (connexin 26, Cx26) gene are the major cause of nonsyndromic hearing impairment in many populations. Genetic testing offers opportunities to determine the cause of deafness and predict the course of hearing, enabling the prognostication of language development. In the current study, we compared severity of hearing impairment in 60 patients associated with biallelic GJB2 mutations and assessed the correlation of genotypes and phenotypes. Within a spectrum of GJB2 mutations found in the Japanese population, the phenotype of the most prevalent mutation, 235delC, was found to show more severe hearing impairment than that of V37I, which is the second most frequent mutation. The results of the present study, taken together with phenotypes caused by other types of mutations, support the general rule that phenotypes caused by the truncating GJB2 mutations are more severe than those caused by missense mutations. The present in vitro study further confirmed that differences in phenotypes could be explained by the protein expression pattern.

Identification of differentially expressed genes in salivary gland tumors with cDNA microarray.

OBJECTIVE: The final goal of this study is to develop a pre-operative fine needle aspiration biopsy (FNA) diagnostic system based on gene expression profiles. As the first step to that end, the present study was performed to determine whether the cDNA microarray system is applicable for histological evaluation of parotid gland tumors. METHODS: We investigated molecular characteristics on the basis of gene expression patterns of the two most common types of salivary gland tumors (pleomorphic adenomas and Warthin tumors) and normal salivary gland tissues, using the cDNA microarray system. RESULTS: Pleomorphic adenomas and Warthin tumors can be classified by cDNA microarray. In pleomorphic adenomas, 11 independent genes were found to be up-regulated and 2 genes were down-regulated. In Warthin tumors, five independent genes were found to be up-regulated, and six genes were down-regulated. In hierarchical clustering analysis, cases were further grouped into two clusters according to the histological type. Furthermore, cDNA microarray enabled pleomorphic adenomas to be subclassified into three clusters according to the histological subtypes. CONCLUSIONS: This study suggested that cDNA microarray may be useful and applicable for the pre-operative diagnosis (such as FNA) of the salivary gland tumor.

The effect of hypergravity on the inner ear: CREB and syntaxin are up-regulated.

cDNA microarray analysis of differential mRNA expression in the rat inner ear under hypergravity identified 20 up-regulated and 2 down-regulated genes. The results demonstrated that various response and/or adaptation processes occur at the level of the peripheral organs. From among the genes assessed by microarray, up-regulation of CREB and syntaxin was confirmed by real time PCR and these two molecules were found to be immunocytochemically localized in the primary afferent neurons. Since CREB is believed to be involved in the formation of long term memory, and syntaxin is known as one of the synaptic molecules involved in the exocytosis of synaptic vesicles, the up-regulation of CREB and syntaxin may reflect synaptic plasticity occurring in the peripheral vestibular system.

Microtubule associated protein (MAP1A) mRNA was up-regulated by hypergravity in the rat inner ear.

Differential display analysis of differential mRNA expression in the rat inner ear under hypergravity identified two down- and four up-regulated genes. The up-regulation of microtubule associated protein 1A (MAP1A) in one of these was confirmed by real-time polymerase chain reaction. Since MAP1A is believed to work as a cell stabilizer connecting the actin with microtubule, this is possibly a response to strengthen this stabilizer under hypergravity. The MAP1A gene is the first found to be affected by gravity change in the inner ear.