Rapid Nitriding of Titanium Alloy with Fine Grains at Room Temperature.

Multifunctional surfaces are required to design safe engineering products for human lives. Heating in a nitrogen atmosphere (nitriding) improves the tribological properties but reduces the strength of titanium (Ti) alloys owing to grain coarsening. A rapid nitriding method for Ti alloys forms the nitrided layer on the surface of a Ti alloy by bombarding with commercially pure Ti fine particles with a nitrided phase at room temperature within a short period. Furthermore, fine grains of Ti alloy are formed in the nitrided layer because of the impact of the Ti particles. These results reveal that this room-temperature method resolves the trade-off between the rapid formation of a nitrided layer and the suppression of grain coarsening for Ti alloys.

Effect of TiB Orientation on Near-Threshold Fatigue Crack Propagation in TiB-Reinforced Ti-3Al-2.5V Matrix Composites Treated with Heat Extrusion.

TiB-reinforced Ti-3Al-2.5V matrix composites, in which TiB whiskers are oriented parallel to the direction of heat extrusion, were fabricated via mechanical alloying and hot isostatic pressing (HIP). To investigate the near-threshold fatigue crack propagation in TiB-reinforced Ti-3Al-2.5V matrix composites, stress intensity factor K-decreasing tests were conducted for disk-shaped compact specimens having two different orientations of TiB whiskers at force ratios from 0.1 to 0.8 under ambient conditions. The crack growth rates, da/dN, for the composites incorporating TiB whiskers oriented perpendicular to the direction of crack growth were constantly lower than those obtained in the case where the orientation was parallel at the same stress intensity range ΔK, while the threshold stress intensity range, ΔKth, was higher. This effect can be explained by the increase in the degree of roughness-induced crack closure resulting from the perpendicular TiB, because fatigue cracks preferentially propagated across the boundaries between the matrix and the TiB in certain regions. In contrast, the effective threshold stress intensity range, ΔKeff,th, for composites was unaffected by the TiB orientation at low force ratios.

Strengthening Mechanism of Titanium Boride Whisker-Reinforced Ti-6Al-4V Alloy Matrix Composites with the TiB Orientation Perpendicular to the Loading Direction.

We fabricated fully dense titanium boride (TiB) whisker-reinforced Ti-6Al-4V alloy matrix (Ti6Al4V-TiB) composites, with a homogeneous dispersion, a TiB orientation perpendicular to the loading direction (; two-dimensional random direction) and an intimate Ti/TiB interface without an intermediate interfacial layer in the Ti-6Al-4V alloy matrix, by spark plasma sintering. Microstructural analysis allows us to present the tensile properties of the Ti6Al4V-TiB composites with the theories for discontinuous fiber-reinforced composites. The Ti6Al4V-TiB 10 vol.% composite yielded a Young's modulus of 130 GPa, an ultimate tensile strength (UTS) of 1193 MPa and an elongation of 2.8%. The obtained experimental Young's modulus and UTS of the Ti6Al4V-TiB composites were consistent with the theoretical values estimated by the Halpin-Tsai and Shear-lag models. The good agreement between our experimental results and these models indicates that the TiB whiskers behave as discontinuous fibers in the Ti-6Al-4V alloy matrix.

Definition of p53 overexpression and its association with the clinicopathological features in luminal/HER2-negative breast cancer.

AIMS: A suitable cut-off value for p53 overexpression and its usefulness as a prognostic factor in luminal/HER2-negative breast cancer were evaluated. PATIENTS AND METHODS: A retrospective analysis of 1,987 patients with luminal/HER2-negative breast cancer who underwent surgery between 2001 and 2009 was performed. RESULTS: p53 expression ≥50% was present in 9% of the patients. Moreover, these patients had significantly lower estrogen/progesterone receptor-positive rates, higher Ki-67 values, larger tumors, disease-positive nodes, higher nuclear grade, and shorter disease-free survival than patients with p53 expression <50% (p<0.0001). Therefore, status of p53-positive cells ≥50% was classified as p53 overexpression. These findings indicate that p53 overexpression is associated with unfavorable characteristics and prognosis. CONCLUSION: The suitable cut-off value for p53 overexpression was determined to be 50%, and p53 overexpression appears to be a significant prognostic factor in patients with luminal/HER2-negative breast cancer.

New evidence about thyroid cancer prevalence: prevalence of thyroid cancer in younger and middle-aged Japanese population.

We have made a cross-sectional investigation of men in the Japanese military for the presence of thyroid abnormalities and thyroid cancer to document the prevalence of thyroid disease in these persons. Six thousand, four hundred and twenty-two Japanese military men and women were screened for thyroid disease by history, physical examination and ultrasound examination. Among them, 6,182 were men 50 years of age, 47 were women 50 years of age, and 149 were men 40 years of age and 44 were women 40 years of age. Among the 50 years old men, thyroid nodules were found in 924 men (14.9%): Nineteen individuals (0.31%) had thyroid cancers ranging from 1 mm to 30 mm in diameter (12.5 mm in mean), pathological TNM staging revealed 7 cases of stage I, 2 cases of stage II and 9 cases of stage III. There was a significant increase in thyroid nodules in 50 years old men compared to that in 40 year old men, but there was no significant difference between men and women (p>0.05). Our data document that the detection rate of thyroid cancer in 50 years old men was 0.31%, and the rate of thyroid nodules increased with age in men, but the frequency of thyroid nodules were similar in men and women of the same age.

Mucocele-like tumor associated with ductal carcinoma in situ diagnosed as mucinous carcinoma by fine-needle aspiration cytology: report of a case.

Mucocele-like tumors (MLTs) of the breast are rare, with only 11 cases reported from Japan and 35 cases from other countries. MLTs of the breast were first described by Rosen in 1986. They are believed to be related to atypical ductal hyperplasia, ductal carcinoma, or mucinous carcinoma. It is difficult to diagnose this tumor preoperatively, and especially difficult to differentiate between benign and malignant forms. We report a case of MLT associated with ductal carcinoma in situ, which was initially diagnosed as fibroadenoma by mammography and ultrasonography, and as mucinous carcinoma by fine-needle aspiration cytology. We discuss the characteristic findings of imaging and the appropriate clinical treatment of this tumor. The characteristic image first signals the possibility of this tumor, following which the diagnosis can be confirmed by pathological examination of a fully excised tumor specimen. Breast-conserving surgery is recommended because of the low risk of high-grade malignancy, even when malignancy is confirmed, and lymph node dissection may be avoided.

Mucinous carcinoma of the duodenum associated with hereditary nonpolyposis colorectal cancer: report of a case.

We herein report a rare case of primary mucinous carcinoma of the duodenum associated with hereditary nonpolyposis colorectal cancer (HNPCC). A 50-year-old man known to have HNPCC based on the Amsterdam criteria I was admitted because of the presence of a duodenal tumor. Duodenoscopy revealed an ulcerated tumor in the posterior wall of the second portion of the duodenum and the malignancy was confirmed by a biopsy. He underwent a pylorus-preserving pancreaticoduodenectomy with a regional lymph node dissection. The histological diagnosis was mucinous carcinoma of the duodenum with lymph node metastasis. High-frequency microsatellite instability (MSI-H) was identified in both the colon and a duodenal specimen based on a microsatellite assay. A germline mutation in the hMSH2 gene was also identified. Even though extracolonic malignancies are associated with HNPCC, duodenal cancer is nevertheless very rare, and only two cases have been reported over the past 20 years. The present case is therefore only the third such case and the patient is herein described with a brief review of the literature.

Complication of thyroidectomy in patients with radiation-induced thyroid neoplasms.

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.

Latency period of thyroid neoplasia after radiation exposure.

OBJECTIVE: To determine the temporal sequence for developing benign and malignant thyroid neoplasms after radiation. SUMMARY BACKGROUND DATA: Therapeutic radiation is associated with thyroid neoplasms in humans and animals. Some question whether thyroid cancers develop de novo or from benign thyroid neoplasms. Little information, however, is available concerning the time to development of benign and malignant thyroid neoplasms after radiation exposure. METHODS: We retrospectively analyzed the records of 171 consecutive patients who had a history of exposure to radiation and were treated surgically at University of California, San Francisco-affiliated hospitals for thyroid neoplasms between 1960 and 1999. RESULTS: There were 66 men and 105 women aged 9 to 80 years (mean, 47.0 years). One hundred patients had benign and 71 had malignant tumors (58 papillary cancers, 10 follicular cancers, 1 Hurthle cell cancer, 1 medullary cancer, and 1 carcinosarcoma). The mean latency period for benign tumors was longer than that for malignant lesions (mean, 34.1 and 28.4 years, P = 0.018; median, 38.0 years and 30.0 years, P = 0.001). Follicular carcinomas developed sooner (mean, 20.5 years; median, 20 years) than did follicular adenomas (mean, 35.3 years; median, 36.5 years; P = 0.003, P = 0.0009). Patients with papillary thyroid cancers presenting as occult papillary cancers (<1 cm) and as a dominant nodule had similar latency periods (mean, 34.0 and 28.0 years P = 0.29; median, 37.5 and 30.5 years, P = 0.09), respectively. CONCLUSION: Although there could be selection bias regarding referral of patients, our data document that malignant thyroid tumors after radiation exposure, including follicular carcinomas, present earlier than do benign thyroid tumors. Occult and manifest papillary thyroid cancers present at about the same time interval after radiation exposure. Our findings question whether benign thyroid neoplasms progress to malignant thyroid neoplasms and that most occult thyroid cancers do not progress to malignant thyroid cancers in radiation-exposed patients.

Parathyroid gland volume increases with postmaturational aging in the rat.

To examine the pathophysiology of the age-related rise in the plasma concentration of parathyroid hormone (PTH), we studied the relationships among plasma immunoreactive PTH (iPTH), parathyroid gland volume, parathyroid cell proliferation rate, renal function, and blood Ca(2+) in male Fischer 344 rats aged 6-28 mo. Plasma iPTH increased 2.5-fold between 6 and 28 mo and correlated with parathyroid gland volume (r = 0.87). Gland volume began to increase as early as 6-12 mo of age and by 28 mo was threefold greater than at 6 mo. Gland expansion was a consequence of hyperplasia stimulated in part by an increase in cell proliferative activity late in life. Blood Ca(2+) and plasma inorganic phosphorus did not change significantly with age. Glomerular filtration rate decreased with age but only after the age of 24 mo. Unlike what has been observed in the human, these data suggest that the age-related increase in plasma iPTH in the rat is linked to parathyroid gland hyperplasia and that early gland growth does not appear to be associated with hypocalcemia or renal insufficiency, but rather to developmentally related metabolic changes. Later in life (>24 mo), the increase in parathyroid cell proliferation rate, further hyperplastic expansion of the gland, and increase in iPTH secretion appear to be associated with renal insufficiency.