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A good prognosis is often achieved in patients who have undergone treatment for human papillary carcinoma of the thyroid. On the assumption that this may be partly attributable to an apoptotic tendency of this special type of tumor, we measured DNA fragmentation, cell death by enzyme-linked immunosorbent assay (ELISA), and the expression of apoptosis-related genes. DNA fragmentation occurred more extensively in malignant tumor cells than in benign thyroid tumors or normal thyroid tissue, as examined by agarose gel electrophoresis and confirmed by the quantitative method using an ELISA kit. Although only expression of the tumor suppressor gene, p53, was increased in the tumor tissue, no expression of other genes, such as Fas, TNF, c-myc, c-fos or bcl-2, was observed in the normal, benign, or malignant tumor tissues, indicating that the roles of these gene functions, if any, were minimal in these tissues. Since p53 is closely related to cellular apoptosis and no point mutation was observed in the transcripts expressed by malignant cells, apoptosis and/or the production of an angiogenesis inhibitor induced by wild-type p53 molecules may be related to the favorable prognosis of patients treated for papillary carcinoma of the thyroid.

Hypothesis The complication rate for thyroidectomy is the same in patients with and without a history of radiation exposure. Design Retrospective medical record review of 171 consecutive patients who had a previous history of radiation treatment and had undergone a thyroid operation from 1961 to 1999. Setting University of California, San Francisco, Medical Center and affiliated hospitals. Patients We selected 107 patients with a history of radiation exposure who had undergone thyroid operations (81 total thyroidectomies) and 107 control patients who underwent comparable operations but had no history of radiation exposure. Results Among patients with a history of radiation exposure (mean age, 47.2 years), there was 1 recurrent nerve injury, 1 external nerve injury, 20 patients with transient hypocalcemia, and 1 patient with a hematoma. Among patients without a history of radiation exposure (mean age, 47.5 years), there were 2 recurrent nerve injuries, 18 patients with transient hypocalcemia, and 1 patient with a hematoma. All cases of hypocalcemia and recurrent nerve injury in both groups were transient. One patient had a permanent superior laryngeal nerve injury. In patients who underwent operations since January 1, 1990, duration of hospitalization was 1.2 days in patients with a history of radiation exposure (65 patients) and 1.1 days in patients without (101 patients). Conclusions Our data document that the risk of transient and permanent complications after total thyroidectomy is similar in patients with and without a history of radiation exposure. The relatively low long-term complication rate supports prophylactic total thyroidectomy for patients with thyroid nodules and a history of radiation exposure.

鉄鉱石を熱媒体として重質油を熱分解し軽質油を得るとともに, 同時に生成するコークスを還元剤として還元鉄を製造するKKIプロセスにおいて, 原料油30バーレル/日のパイロットプラントの実験データにより, 2塔式循環流動層における循環推進力モデルを導いた.すなわち, 反応塔, 加熱塔の両塔をたすきがけで結ぶ移送管をオーバフローで流下するいわゆる自然循環において, 鉱石の循環推進力は, 流動層本体下部と移送管下部との合流部での両者の静圧差によって求められるというものである.このモデルにより, 鉱石の循環量および循環方向のコントロールは流動層本体と移送管へ吹き込むスチーム量を変え, 両者の静圧差を変化させることで容易に行うことができる.

Mode conversion of a Gaussian beam due to random fluctuations of a turbulent medium is discussed. The mean-square value of the mode-conversion coefficient (i.e., the power occupation of the higher mode in the perturbed field) is obtained by the perturbation technique. The results show that mode conversion decreases in the neighborhood of the focal point of a focused beam and that the decrease at that point becomes significant when the aperture size is large compared with the scale of the turbulence of the medium. The influence of the anisotropy of the fluctuations on mode conversion is also discussed.

In order to clarify the effects of nitriding and hybrid surface modification process combining nitriding and induction hardening on fatigue properties of SCM435H steel, high cycle fatigue tests were carried out with a rotational bending machine at room temperature. Observations of fracture surfaces and measurement of hardness and residual stress distributions were carried out to investigate the fracture mechanism. It was revealed that hybrid surface modification process generated a compressive residual stress field and hardened even at center of the specimen. Fatigue strength of hybrid surface modified specimens was much higher than that of substrate and nitrided specimens. This was because a transition of fracture mode from internal to surface fracture; fatigue fracture of nitrided specimens occurred at inside of the hardened layer, in the case of hybrid surface modified specimens, however, fatigue crack initiated at the surface of the specimen with higher hardness and higher compressive residual stress.