Tatsuya Furukawa

Study of the wurtzite zinc-blende mixed-structured GaAs nanocrystals grown on Si (111) substrates

The structure and growth mechanism of GaAs nanocrystals grown on Si (111) substrates by using the molecular beam epitaxy method have been studied using transmission electron microscopy. The isolated nanocrystals had hexangular shapes, with aspect ratio ∼1 and high symmetry. The crystal structure of the GaAs nanocrystals contains a mixture of a stable state of zinc-blende and a metastable state of wurtzite. A number of thin wurtzite layers parallel to the Si (111) plane are introduced into the zinc-blende GaAs nanocrystals as stacking faults. Formation of partial dislocations near the GaAs/Si interface and the small difference in the Gibbs free energy between the zinc-blende and wurtzite structures could cause formation of wurtzite as stacking faults in the zinc-blende structure

Nonsteroidal Anti-inflammatory Drug Treatment for Desmoid Tumor Recurrence after Surgery

D esmoid tumors are rare nonmetastasizing fibrous lesions that tend to invade locally. The main treatment for desmoids is wide local excision, but incomplete resection of the tumor margin occasionally occurs, resulting in relapse and the need for repeat operation. Chemotherapy and radiotherapy have been attempted with good responses for unresectable or recurrent lesions, but the side effects may offset the advantages. We present a case of desmoid tumor in the neck region. Hyogo Cancer Center Institutional Review Board approval and informed consent were obtained. This patient underwent 5 operations, but the tumor continued to relapse after every surgery. Intriguingly, the tumor finally regressed after the use of a nonsteroidal anti-inflammatory drug (NSAID) for neck pain.

Epigenetic down-regulation of SOX2 is an independent poor prognostic factor for hypopharyngeal cancers

We recently reported that a small subset (7%) of oesophageal squamous cell carcinomas completely lacking SOX2 expression had unique clinicopathological features and a dismal prognosis. The aim of the present study was to elucidate whether the findings obtained in oesophageal cancers are applicable to hypopharyngeal squamous cell carcinomas (HPSCCs) or oropharyngeal squamous cell carcinomas (OPSCCs).

Postoperative hypoparathyroidism after total thyroidectomy for thyroid cancer

OBJECTIVES Postoperative hypoparathyroidism (HPT) is one of the most common complications in total thyroidectomy for thyroid carcinoma. Parathyroid glands (PTGs) are at risk of being damaged during total thyroidectomy and central neck dissection mainly due to inadvertent removal, interruption of the blood supply or hematoma formation. The purpose of this study was to evaluate the efficacy of our surgical procedure to preserve for parathyroid function retrospectively and to clarify the risk factors of HPT after total thyroidectomy for thyroid cancer. PATIENTS AND METHODS Sixty-five patients undergoing total thyroidectomy with central neck dissection for thyroid cancer were enrolled in this retrospective study. Cancers were diagnosed as stage I in 15 patients, stage II in 24 patients, stage III in 19 patients, and stage IV in 7 patients. Lateral neck dissection and upper mediastinal dissection were simultaneously performed in 47 patients and one patient, respectively. Parathyroid glands (PTGs) were preserved in situ in 34 patients. Among 31 patients in whom PTG could not be preserved in situ, two or more PTGs were autotransplanted in 9 patients and one PTG was autotransplanted in 18 patients. PTG was not autotransplanted in 4 patients, since it could not be identified during the surgery. RESULTS Postoperative transient HPT and permanent HPT were observed in 44 (68%) patients and in 12 (18%) patients, respectively. Among 34 patients in whom PTGs were preserved in situ, transient HPT and permanent HPT were observed in 17 (50%) patients and in 6 (2%) patients, respectively. Among 31 patients in whom PTG were not preserved in situ, postoperative permanent HPT was observed in all 4 patients without PTG autotransplantation, and 6 (33%) out of the 18 patients who had one PTG autotransplantation. On the other hand, none of the 9 patients who had two or more PTG autotransplantation at the time of thyroidectomy developed permanent HPT (P=0.04). The patients with large tumor (≥40mm) and/or gross extra glandular invasion had a significantly higher risk of permanent postoperative HPT compared with the patients without these pathological features (P<0.01). CONCLUSIONS Two or more PTG should be autotransplanted in case where PTG is not preserved in situ to prevent postoperative HPT after total thyroidectomy with central neck dissection, especially in cases of large tumor and/or gross extrathyroidal extension.

Transoral videolaryngoscopic surgery for papillary carcinoma arising in lingual thyroid

Carcinoma arising in lingual thyroid is an extremely rare entity accounting for only 1% of all reported ectopic thyroids. Here, we report a case of carcinoma arising in lingual thyroid, which has been successfully managed by transoral resection and bilateral neck dissections. A lingual mass 4-cm in diameter with calcification was incidentally detected by computed tomography at medical check-up. No thyroid tissue was observed in normal position. Ultrasound examination showed bilateral multiple lymphadenopathies. Fine needle aspiration biopsy from lymph node in his right neck was diagnosed as Class III and thyroglobulin level of the specimen was 459ng/ml. Due to the difficulty in performing FNA of the lingual masses, right neck dissection was performed in advance for diagnostic purpose. Pathological examination showed existence of large and small follicular thyroid tissues in several lymph nodes, suggesting lymph node metastasis from thyroid carcinoma. Two months after the initial surgery, video-assisted transoral resection of lingual thyroid with simultaneous left neck dissection was performed. Postoperative course was uneventful. Papillary carcinoma was found in the lingual thyroid and thyroid tissues were also found in left cervical lymph nodes. Video-assisted transoral resection was useful for the treatment of thyroid cancer arising in lingual thyroid.

Isosorbide-Induced Decompression Effect on the Scala Media: Participation of Plasma Osmolality and Plasma Arginine Vasopressin

OBJECTIVE The correlation between the isosorbide-induced decompression effect on the endolymphatic space and plasma osmolality (p-OSM) or plasma arginine vasopressin (p-AVP) was investigated on comparing two different dosages of isosorbide (2.8 and 1.4 g/kg) to elucidate why the decompression effect is delayed with a large dose of isosorbide. MATERIALS AND METHODS Two experiments were performed using 80 guinea pigs. Experiment 1 was designed to morphologically investigate the sequential influence of the oral intake of 1.4- and 2.8-g/kg doses of isosorbide on the endolymphatic volume. The animals used were 50 guinea pigs (control: 10, experimental: 40). All animals underwent surgical obliteration of the endolymphatic sac of the left ear. One month after the surgery, control animals were sacrificed 3 hours after the intake of distilled water, and experimental animals were sacrificed 3 and 6 hours after the isosorbide intake. All of the left temporal bone served for the quantitative assessment of changes in the endolymphatic space, and the cross-sectional area of the scala media was measured from the mid-modiolar sections of the cochlea.Experiment 2 was designed to investigate changes in p-OSM and p-AVP levels 3 hours after the oral intake of isosorbide. Animals used were 15 guinea pigs (control: 5, experimental: 10). The control group received the oral administration of distilled water (4 ml/kg), and the experimental animals were subdivided into two groups consisting of 10 animals each by the dosage of isosorbide (1.4 or 2.8 g/kg). All animals were sacrificed for the measurement of p-OSM and p-AVP concentrations 3 hours after the intake of water or 70% isosorbide solution. RESULTS Morphologically, an isosorbide-induced decompression effect was noted in animals with both 1.4- and 2.8-g/kg doses of isosorbide. According to the regression analysis, however, the volumetric decrease of the endolymphatic space was more evident in cases with the small dose (1.4 g/kg) 3 hours after the intake (analysis of covariance [ANCOVA], p < 0.001). Six hours after, the decompression effect was significantly greater in cases with the large dose (2.8 g/kg) (ANCOVA, p < 0.001).Isosorbide intake caused a rise in p-OSM levels dose-dependently. The Cochran-Cox test revealed that the differences in the mean values among control and isosorbide groups were significant (p < 0.01). Regarding the p-AVP level, a significant increase was evident in cases with the large dose (2.8 g/kg) (p < 0.01, Cochran-Cox test), and not in cases with the small dose (1.4 g/kg). CONCLUSION An isosorbide-induced decompression effect of the endolymphatic space was evident in spite of two different dosages of isosorbide (2.8 and 1.4 g/kg). Three hours after the isosorbide intake, however, the decompression effect was more marked in the group with the small dose (1.4 g/kg). Since significant rises in p-OSM and p-AVP were evident in the group with the large dose, this early rise of p-AVP due to dehydration seems to be the major reason for the delayed decompression effect in cases with a large isosorbide intake.

Structural Stabilities in GaAs Nanocrystals Grown on Si (111) Surface

Structural stabilities in GaAs nanocrystals grown on the Si (111) substrate have been studied by transmission electron microscopy in order to see the structure and growth mechanism. The GaAs nanocrystals grown epitaxially on the Si (111) surface kept at 573 K have thin shapes consisting of a flat surface which is parallel to the Si (111) surface. The crystalline structure of the initial growth layer, below approximately 5 nm in thickness is zincblend, but with increasing thickness the structure changes to the wurtzite structure by formation of orderly-arranged stacking faults. The small difference in the driving force between wurtzite and the zincblende structure could lead to a situation where the kinetic rate of nucleus formation is higher for the wurtzite structure than for the zincblende structure. It would highly increase the probability that the wurtzite structure is formed as a non-equilibrium state.