Magnetic Resonance Imaging Compatibility of the Polymer-based Cochlear Implant

ObjectivesIn this study, we compared the magnetic resonance (MR) image artifacts caused by a conventional metal-based cochlear implant and a newly developed liquid crystal polymer (LCP)-based device.MethodsThe metal-based cochlear implant system (Nurobiosys Co.) was attached to side of the head of a subject and the LCP-based device was attached to opposite side. In both devices, alignment magnets were removed for safety. Magnetic resonance imaging (MRI) was performed on a widely used 3.0 T and an ultra-high 7.0 T MRI machine. 3.0 and 7.0 T MR images were acquired using T1- and T2*-weighted gradient echo sequences, respectively.ResultsIn the 3.0 T images, the metal-based device on the left side generated the significant amount of artifacts. The MR images in the proximity of the metal package were obscured by the artifacts in both axial and sagittal views. On the other hand, the MR images near the LCP-based device were relatively free from the artifacts and clearly showed the brain structures. 7.0 T MR images showed the more severe distortion in the both sides but the metal-based cochlear implant system caused a much larger obscure area than the LCP-based system.ConclusionThe novel LCP-based cochlear implant provides a good MRI compatibility beyond present-day cochlear implants. Thus, MR images can be obtained from the subjects even with the implanted LCP-based neural prosthetic systems providing useful diagnostic information. Furthermore, it will be also useful for functional MRI studies of the auditory perception mechanism after cochlear implantations as well as for positron emission tomography-MRI hybrid imaging

Perinatal Outcome in Twin Pregnancies Complicated by Gestational Diabetes Mellitus: A Comparative Study

The purpose of this study is to compare perinatal outcomes of twin pregnancies complicated by gestational diabetes (GDM) with those unaffected by GDM. A total of 1,154 twin pregnancies who delivered at Cheil General Hospital, between January 1998 and December 2002 were recruited to participate in a retrospective analysis. Out of these twin pregnancies, 37 women were had GDM. Four pregnancies exposed to GDM were excluded due to the loss of medical records; therefore 33 twin pregnancies exposed to GDM were enrolled. We matched the GDM pregnancies with pregnancies unaffected by GDM in a 1:2 ratio; therefore there were 33 GDM/66 without GDM who delivered during the study period. Our findings show that there were no significant differences including birth weight, Apgar score, respiratory distress syndrome, meconium aspiration pneumonia, transient tachypnea of new born, hyperbilirubinemia, hypoglycemia, hypocalcemia and congenital anomalies. Therefore, well controlled GDM may not increase perinatal complications in twin pregnancies. Careful pregnancy management and fetal surveillance in twin pregnancies is important to decrease perinatal complications and maintain a sound pregnancy and healthy offspring

The Distribution of Fetal Nuchal Translucency Thickness in Normal Korean Fetuses

The aim of present study was to establish normative data for the distribution of nuchal translucency (NT) thickness in normal Korean fetuses. The data were collected from pregnant women with singleton pregnancies in whom fetal ultrasound was performed and the fetal NT thickness was measured between 11 and 14 weeks of gestation. Among them, a total of 2,577 fetuses with a known normal outcome were included in this study. The distribution of multiple of median (MoM) values of the NT thickness with crown-rump length (CRL) in 10-mm intervals and the 95th percentile of MoM were calculated with the linear regression method. The present study showed that NT measurements increase with increasing CRL and a false positive rate increases with increasing gestational age. Therefore, a fixed cut-off point through the first trimester was not appropriate and each NT measurement should be examined according to the gestational age. The present study offers normative data of the fetal NT thickness in a Korean population, which can be used as reference for screening chromosomal aberrations or other congenital abnormalities in the first trimester

The complete mitochondrial genome of Yuukianura szeptyckii Deharveng & Weiner 1984 (Collembola: Neanuridae)

The complete mitochondrial genome of Yuukianura szeptyckii Deharveng & Weiner 1984 was sequenced, assembled, and annotated. The mitochondrial genome of Y. szeptyckii has a length of 15,771 bp and contains 13 protein-coding genes (PCGs), 22 transfer (tRNA) genes, and 2 ribosomal RNA (rRNA) genes. Y. szeptyckii was closely clustered with the following species of Neanuridae: Bilobella aurantiaca and Friesea grisea

Nanocage-Confined Synthesis of Fluorescent Polycyclic Aromatic Hydrocarbons in Zeolite

Polycyclic aromatic hydrocarbons (PAHs) attract much attention for applications to organic light-emitting diodes, field-effect transistors, and photovoltaic cells. The current synthetic approaches to PAHs involve high-temperature flash pyrolysis or complicated step-bystep organic reactions, which lead to low yields of PAHs. Herein, we report a facile and scalable synthesis of PAHs, which is carried out simply by flowing acetylene gas into zeolite under mild heating, typically at 400 degrees C and generates the products of 0.30 g g(-1) zeolite. PAHs are synthesized via acetylene polymerization inside Ca2+-ion-exchanged Linde type A (LTA) zeolite, of which the alpha-cage puts a limit on the product molecular size as a confined-space nanoreactor. The resultant product after the removal of the zeolite framework exhibits brilliant white fluorescence emission in N-methylpyrrolidone solution. The product is separated into four different color emitters (violet, blue, green, and orange) by column chromatography. Detailed characterizations of the products by means of various spectroscopic methods and mainly mass spectrometric analyses indicate that coronene (C24H12) is the main component of the blue emitter, while the green emitter is a mixture of planar and curved PAHs. The orange can be attributed to curved PAHs larger than ovalene, and the violet to smaller molecules than coronene. The PAH growth mechanism inside Ca2+ -exchanged LTA zeolite is proposed on the basis of mass spectral analyses and density functional theory calculation

Nanocage-confined synthesis of fluorescent polycyclic aromatic hydrocarbons in zeolite

Polycyclic aromatic hydrocarbons (PAHs) attract much attention for applications to organic light-emitting diodes, field-effect transistors, and photovoltaic cells. The current synthetic approaches to PAHs involve high-temperature flash pyrolysis or complicated step-by-step organic reactions, which lead to low yields of PAHs. Herein, we report a facile and scalable synthesis of PAHs, which is carried out simply by flowing acetylene gas into zeolite under mild heating, typically at 400 °C and generates the products of 0.30 g g–1 zeolite. PAHs are synthesized via acetylene polymerization inside Ca2+-ion-exchanged Linde type A (LTA) zeolite, of which the α-cage puts a limit on the product molecular size as a confined-space nanoreactor. The resultant product after the removal of the zeolite framework exhibits brilliant white fluorescence emission in N-methylpyrrolidone solution. The product is separated into four different color emitters (violet, blue, green, and orange) by column chromatography. Detailed characterizations of the products by means of various spectroscopic methods and mainly mass spectrometric analyses indicate that coronene (C24H12) is the main component of the blue emitter, while the green emitter is a mixture of planar and curved PAHs. The orange can be attributed to curved PAHs larger than ovalene, and the violet to smaller molecules than coronene. The PAH growth mechanism inside Ca2+-exchanged LTA zeolite is proposed on the basis of mass spectral analyses and density functional theory calculations

The complete mitochondrial genome of Allonychiurus kimi (Lee, 1973) (Collembola: Onychiuridae)

The complete mitochondrial genome of Allonychiurus kimi (Lee, ) was sequenced, assembled, and annotated. The mitochondrial genome of A. kimi is 14,386 bp in length and contains 13 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes. A. kimi was closely clustered with the following species of the family Onychiuridae: Onychiurus orientalis, Orthonychiurus forlsomi, and Tetrodontophora bielanensis

A Calcitonin-Negative Neuroendocrine Tumor Derived from Follicular Lesions of the Thyroid

Neuroendocrine lesions of the thyroid are rare. The most common types are medullary thyroid carcinomas (MTCs) and C-cell hyperplasia. MTCs originate from thyroid parafollicular cells that secrete calcitonin which serves as a serum marker of MTCs. Here, the rare case of a calcitonin-negative neuroendocrine tumor (NET) derived from follicular lesions of the thyroid is described. A 34-year-old man presented at our hospital for the surgical management of an incidental thyroid nodule that was observed on an ultrasound sonography (USG) of the neck. Initially, USG-guided aspiration cytology was performed, and a MTC was suspected. The expressions of thyroglobulin and thyroid transcription factor-1, which are thyroid follicular cell markers, and synaptophysin and chromogranin A, which are neuroendocrine markers, was confirmed following surgical pathology. However, the staining of calcitonin, a marker of MTCs, was not observed. A nonmedullary NET of the thyroid is uncommon, and the distinction between calcitonin-negative NETs and MTCs of the thyroid may be important due to differences in their clinical courses and management