Daisuke Yamashita

Increased Inner Ear Susceptibility to Noise Injury in Mice With Streptozotocin-Induced Diabetes

We aimed to investigate the pathophysiology of diabetes-associated hearing impairment in type 1 diabetes using mice with streptozotocin-induced diabetes (C57BL/6J; male). Hearing function was evaluated 1, 3, and 5 months after induction of diabetes (five diabetic and five control animals per time point) using auditory-evoked brain stem responses (ABRs). Mice (four diabetic and four control) were exposed to loud noise (105 dB) 5 months after induction of diabetes. ABRs were measured before and after noise exposure. Cochlear blood flows were measured by laser-Doppler flowmeter. Spiral ganglion cells (SGCs) were counted. Vessel endothelial cells were observed by CD31 immunostaining. Chronologic changes in the ABR threshold shift were not significantly different between the diabetic and control groups. However, vessel walls in the modiolus of the cochleae were significantly thicker in the diabetic group than the control group. Additionally, recovery from noise-induced injury was significantly impaired in diabetic mice. Reduced cochlea blood flows and SGC loss were observed in diabetic mice cochleae after noise exposure. Our data suggest that diabetic cochleae are more susceptible than controls to loud noise exposure, and decreased cochlear blood flow due to sclerosis of the vessels and consequent loss of SGCs are possible mechanisms of hearing impairment in diabetic patients.

Neurological outcomes in symptomatic congenital cytomegalovirus-infected infants after introduction of newborn urine screening and antiviral treatment

BACKGROUNDnNewborn screening for urinary cytomegalovirus (CMV) and early introduction of antiviral treatment are expected to improve neurological outcomes in symptomatic congenital CMV-infected infants. This cohort study prospectively evaluated neurological outcomes in symptomatic congenital CMV-infected infants following the introduction of hospital-based newborn urinary CMV screening and antiviral treatment.nnnSUBJECTS/METHODSnFollowing institutional review board approval and written informed consent from their parents, newborns were prospectively screened from 2009 to 2014 for urinary CMV-DNA by PCR within 1 week after birth at Kobe University Hospital and affiliated hospitals. CMV-positive newborns were further examined at Kobe University Hospital, and those diagnosed as symptomatic were treated with valganciclovir for 6 weeks plus immunoglobulin. Clinical neurological outcomes were evaluated at age ⩾12 months and categorized by the presence and severity of neurologic sequelae.nnnRESULTSnUrine samples of 6348 newborns were screened, with 32 (0.50%) positive for CMV. Of these, 16 were diagnosed with symptomatic infection and 12 received antiviral treatment. Four infants developed severe impairment (33%), three developed mild impairment (25%), and five developed normally (42%).nnnCONCLUSIONSnThis is the first Japanese report of neurological assessments in infants with symptomatic congenital CMV infection who received early diagnosis and antiviral treatment. Urinary screening, resulting in early diagnosis and treatment, may yield better neurological outcomes in symptomatic congenital CMV-infected infants.

Concomitant chemoradiotherapy for advanced squamous cell carcinoma of the temporal bone.

The purpose of this study was to analyze outcomes for the treatment of locally advanced temporal bone cancer by means of concomitant chemoradiotherapy (CCRT) with a combination of cisplatin (CDDP), 5‐fluorouracil (5‐FU), and docetaxel (TPF).

Magnetic resonance monitoring of superparamagnetic iron oxide (SPIO)-labeled stem cells transplanted into the inner ear

In the field of regenerative medicine, cell transplantation or cell-based therapies for inner ear defects are considered to be promising candidates for a therapeutic strategy. In this paper, we report on a study that examined the use of magnetic resonance imaging (MRI) to monitor stem cells transplanted into the cochlea labeled with superparamagnetic iron oxide (SPIO), a contrast agent commonly used with MRI. First, we demonstrated in vitro that stem cells efficiently took up SPIO particles. This was confirmed by Prussian blue staining and TEM. In MRI studies, T2 relaxation times of SPIO-labeled cells decreased in a dose-dependent manner. Next, we transplanted SPIO-labeled cells directly into the cochlea in vivo and then performed MRI 1h, 2 weeks, and 4 weeks after transplantation. The images were evaluated objectively by measuring signal intensity (SI). SI within the ears receiving transplants was significantly lower (P<0.05) than that of control sides at the 1-h assessment. This novel method will be helpful for evaluating stem cell therapies, which represents a new strategy for inner ear regeneration. To the best of our knowledge, this study is the first to demonstrate that local transplantation of labeled stem cells into the inner ear can be visualized in vivo via MRI.

A high-fat diet delays age-related hearing loss progression in C57BL/6J mice.

Objective Age-related hearing loss (AHL), or presbycusis, is the most common sensory disorder among the elderly. We used C57BL/6J mice as an AHL model to determine a possible association between AHL and a high-fat diet (HFD). Methods Forty C57BL/6J mice were randomly assigned to a control or HFD group. Each group was divided into the following subgroups: 1-, 3-, 5- and 12-month groups (HFD, n = 5/subgroup; control, n = 5/subgroup). Nine CBA/N-slc mice were also used as a 12-month control (n = 5) or 12-month HFD (n = 4) group. The mice were fed a HFD or normal (control) diet throughout this study. Hearing function was evaluated at 1, 3, 5 and 12 months using auditory evoked brainstem responses (ABRs). Spiral ganglion cells (SGCs) were also counted. Results The elevation of ABR thresholds (at 4 and 32 kHz) at 3 and 5 months was significantly suppressed in the HFD group compared with the control groups for C57BL/6J mice. After 12 months, the elevation of ABR thresholds was significantly suppressed in the HFD group at all frequencies for C57BL/6J mice. In contrast, CBA/N-slc mice displayed opposite outcomes, as ABR thresholds at all frequencies at 12 months were significantly elevated in the HFD group compared with the control group. For the C57BL/6J mice at 12 months, SGC numbers significantly decreased in all parts of the cochleae in the control group compared with the HFD groups. In contrast, for the CBA/N-slc mice, SGC numbers significantly decreased, particularly in the upper parts of the cochleae in the HFD group compared with the control groups. Conclusions The elevation in ABR thresholds and SGC loss associated with aging in the HFD-fed C57BL/6J mice were significantly suppressed compared with those in the normal diet-fed mice. These results suggest that HFD delays AHL progression in the C57B/6J mice.

Oral candidiasis mimicking tongue cancer

Candida species inhabit the mucosal surfaces of healthy individuals. Major forms of oral candidiasis are pseudomembranous and atrophic form, but chronic hyperplastic candidiasis (CHC) is rarely seen. We encountered a nodule caused by candidal infection on a forearm flap in the oral cavity mimicking a recurrent tongue cancer, which revealed as CHC by histopathological examination. Like other forms of oral candidiasis, the nodule well responded to the treatment of antifungal agents and eventually disappeared. When an intraoral nodule is observed, the possibility of CHC should be taken into consideration.

Metabolomic profiling in inner ear fluid by gas chromatography/mass spectrometry in guinea pig cochlea.

The composition and homeostasis of inner ear fluids are important in hearing function. The purpose of this study was to perform metabolomic analysis of the inner ear fluid in guinea pig cochlea, which has not been previously reported in literature, using gas chromatography/mass spectrometry (GC/MS). Seventy-seven kinds of metabolites were detected in the inner ear fluid. Six metabolites, ascorbic acid, fructose, galactosamine, inositol, pyruvate+oxaloacetic acid, and meso-erythritol, were significantly more abundant, and nine metabolites, phosphate, valine, glycine, glycerol, ornithine, glucose, citric acid+isocitric acid, mannose, and trans-4-hydroxy-L-proline, were less abundant in the inner ear fluid than in plasma. The levels of ten metabolites, 3-hydroxy-butyrate, glycerol, fumaric acid, galactosamine, pyruvate+oxaloacetic acid, phosphate, meso-erythritol, citric acid+isocitric acid, mannose, and inositol, in the inner ear fluid significantly changed after loud noise exposure. These observations may help to elucidate various clinical conditions of sensorineural hearing loss, including noise-induced hearing loss.

Xeroderma pigmentosum clinical practice guidelines

Xeroderma pigmentosum (XP) is a genetic photosensitive disorder in which patients are highly susceptibe to skin cancers on the sun‐exposed body sites. In Japan, more than half of patients (30% worldwide) with XP show complications of idiopathic progressive, intractable neurological symptoms with poor prognoses. Therefore, this disease does not merely present with dermatological symptoms, such as photosensitivity, pigmentary change and skin cancers, but is “an intractable neurological and dermatological disease”. For this reason, in March 2007, the Japanese Ministry of Health, Labor and Welfare added XP to the neurocutaneous syndromes that are subject to government research initiatives for overcoming intractable diseases. XP is one of the extremely serious photosensitive disorders in which patients easily develop multiple skin cancers if they are not completely protected from ultraviolet radiation. XP patients thus need to be strictly shielded from sunlight throughout their lives, and they often experience idiopathic neurodegenerative complications that markedly reduce the quality of life for both the patients and their families. Hospitals in Japan often see cases of XP as severely photosensitive in children, and as advanced pigmentary disorders of the sun‐exposed area with multiple skin cancers in adults (aged in their 20–40s), making XP an important disease to differentiate in everyday clinical practice. It was thus decided that there was a strong need for clinical practice guidelines dedicated to XP. This process led to the creation of new clinical practice guidelines for XP.

Patterns of lymph node metastasis of parotid cancer

OBJECTIVEnTo define the incidence and pattern of spread of lymph node metastasis from parotid cancers and to clarify the risk factors and appropriate extent of neck dissection (ND) for individual patient with parotid cancer.nnnMETHODSnA total of 72 patients with parotid gland cancer treated by surgery between 1994 and 2013 were analyzed retrospectively by reference to medical records. In line with our protocol, patients with clinically positive lymph nodes and/or cT3/T4 disease were generally selected to undergo ND.nnnRESULTSnPathological examinations revealed mucoepidermoid carcinoma in 23 patients, carcinoma ex pleomorphic adenoma in 11, adenoid cystic carcinoma in 9, salivary duct carcinoma in 9, acinic cell carcinoma in 8, squamous cell carcinoma in 5, adenocarcinoma NOS in 4, epithelial myoepithelial carcinoma in 2, and basal cell carcinoma in 1. Thirty-three patients underwent neck dissection: modified radical ND (MRND) in 13, and elective ND (END) in 20. Postoperative RT (PORT) was performed in 33 patients. Among 13 cN+ patients, 10 were pN+ and lymph node metastasis was distributed mainly in levels I, II, III and V. Among 59 cN- patients, clinical T1, T2, T3 and T4 classifications accounted for 10, 24, 10 and 15 patients, respectively. The incidence of occult lymph node metastasis was 22%. Occult lymph node metastasis was mostly seen in the intraparotid, levels I and II of patients with cT4 disease. Among the ND group, 12 necks were pathologically negative for cancer (pN0). Relapse of neck lymph node metastasis occurred only in two patients treated by MRND with pathologically positive lymph nodes (pN+). These patients developed local and distant metastasis within 1 year after neck lymph node recurrence, and subsequently died of the cancer. pN+ was found in 19/30 high grade (63%), 1/10 intermediate grade (10%), and 3/32 low grade (9.4%). Among 33 patients who received PORT, only 1 patient relapsed neck lymph node.nnnCONCLUSIONnFor patients with clinically positive lymph nodes, ipsilateral modified radical neck dissection (levels I-V) is recommended. Elective neck dissection is strongly recommended for patients with T3N0 or T4N0 disease, and the extent of ND should include at least level I/II. PORT for patients with high-risk features may improve the outcome of good neck control.

Hearing Dysfunction in Xpa-Deficient Mice

Xeroderma pigmentosum (XP) is a rare recessive heredity disease caused by DNA repair impairment characterized by photosensitivity and neurologic symptoms in half of the cases. There are eight subtypes of XP: XP-A–XP-G and XP variant. Among eight subtypes, XP complementation group A (XP-A) display the lowest DNA repair ability and the severest cutaneous and neurologic symptoms. While its pathogenesis of skin symptoms have been well-studied, that of neurological symptoms, including sensorineural hearing loss (SNHL) remains unknown. Basic studies have suggested that SNHL may be caused by inner ear damage, including damage to the spiral ganglion neurons and organ of Corti, and that the XP-A is associated with most severe form of SNHL in humans. Here, we report the occurrence of SNHL in Xpa-deficient mice. Xpa-deficient mice and wild-type mice underwent measurements for auditory brainstem response, and the results revealed that Xpa-deficient mice exhibited significantly greater (p < 0.01) ABR thresholds at 4, 8, and 16 kHz than the wild-type mice. Furthermore, the number of spiral ganglion neurons was reduced in Xpa-deficient mice compared with that in wild-type mice, indicating that hearing loss may be related to spiral ganglion neuron deficiency, consistent with the few reports published in human patients with XP. These results provide important insights into the pathogenesis of SNHL in patients with XP-A.