Cochlear Melanocytes and MITF Signaling

Melanocytes occur not only in the skin and eyes but in the cochlea, where they exist as intermediate cells of the stria vascularis. Intermediate cells play an important role for cochlear function: Na+K+-ATPase and potassium channels of intermediate cells are essential for production of endocochlear potential and for preparation of ionic milieu in the stria. Consistent with this notion, melanocyte deficiency due to some gene disruptions results in hearing impairment in mice and humans. Mitf/MITF is essential for development and maturation of melanocytes, including strial intermediate cells. Disruption of MITF causes deafness, heterochromia irides, and leucodermia in Waardenburg syndrome type 2 individuals, whereas that of Mitf causes phenotypes of deafness, microphthalmia, and white coat in mice. Again, all of these phenotypes may be explained by a lack of melanocytes. Many signal transduction pathways target the Mitf/MITF gene or Mitf/MITF protein, and disruption of these pathways sometimes results in the phenotype similar to that caused by Mitf/MITF disruption. If not all, certainly many roads lead to MITF in melanocytes

Papillary Thyroid Carcinoma Arising from a Median Ectopic Thyroid with No Thyroglossal Duct Remnant

Thyroid carcinomas arising from ectopic thyroid tissue are uncommon;most of them arise from thyroid tissue in thyroglossal cysts. A rare case of a 66-year-old woman with papillary thyroid carcinoma arising from median ectopic thyroid tissue lacking a thyroglossal duct remnant is reported. The tumor was resected by Sistrunk's procedure, and the patient's postoperative course was good

Tracheal Stenosis Caused by Unnoticed Foreign Bodies

We describe an extremely rare case of tracheal stenosis caused by unnoticed microscopic fiber-like foreign bodies. A 66-year-old woman complained of dyspnea with inspiratory stridor. Magnifying electroendoscopy and computed tomography revealed stenosis involving the entire circumference of the tracheal lumen. Tracheotomy and biopsy were performed. Histologically, the lesion showed chronic inflammation with a deposition of fiber-like foreign bodies. The patient had no history of trauma or inhalation injury, but had undergone intratracheal intubation on 4 occasions. The lesion was incised using semiconductor laser photoresection, and the postoperative course was good. To the best of our knowledge, this represents the first report in the English literature of tracheal stenosis caused by unnoticed foreign bodies. The origin of these fiber-like foreign bodies remains unclear but might be related to chronic inflammation resulting from intratracheal intubations

A BIST Scheme for Dynamic Comparators

This paper proposes a built-in self-test (BIST) scheme for detecting catastrophic faults in dynamic comparators. In this scheme, a feedback loop is designed using the characteristics of the comparator; monitoring the voltage in the feedback loop can determine the presence of a circuit fault. The proposed BIST scheme and the circuit under testing are realized at the transistor level. The proposed BIST scheme was simulated using HSPICE. The simulated fault coverage is approximately 87.8% with 90 test circuits. To further verify the effectiveness of the proposed BIST scheme, six faults were injected into the real circuit. The test results were consistent with the simulation results