Corrosion Behavior of Ultrafine-Grained CoCrFeMnNi High-Entropy Alloys Fabricated by High-Pressure Torsion

The influence of the nanocrystalline structure produced by severe plastic deformation (SPD) on the corrosion behavior of CoCrFeMnNi alloys with Cr contents ranging from 0 to 20 at.% was investigated in aqueous 0.5 M H₂SO₄ and 3.5% NaCl solutions. The resistance to general corrosion and pitting became higher in both the solutions, with higher passivation capability observed with increasing Cr content, and it is believed that the high corrosion resistance of CoCrFeMnNi alloys can be attributed to the incorporation of the Cr element. However, the impact of the nanocrystalline structure produced by SPD on the corrosion behavior was negligibly small. This is inconsistent with reports on nanocrystalline binary Fe–Cr alloys and stainless steels processed by SPD, where grain refinement by SPD results in higher corrosion resistance. The small change in the corrosion behavior with respect to grain refinement is discussed, based on the passivation process of Fe–Cr alloys and on the influence of the core effects of HEAs on the passivation process.     

Medical migration: A qualitative exploration of the atypical path of Japanese international medical graduates

Background: International Medical Graduates (IMGs) are commonly understood to move from low to high resource countries with motivations including improved financial situations and cultures of emigration. A presumable exception to the above themes would be the Japanese IMG population. The aim of this study was to develop an understanding of the Japanese IMG experience.

Methods: Using a grounded theory approach, we interviewed 19 Japanese IMGs working in the US and 16 Japanese IMGs working in Japan who had completed US clinical training. Questions addressed decision-making to pursue US clinical training, goals for the training, and career decision-making upon completing the training. Data collection and constant comparative analysis were conducted iteratively to identify emerging themes.

Results: The emerging model of the Japanese IMG experience is focused around pivotal experiences that often include dissatisfaction with the quality of Japanese clinical training and personal exposures to US clinical education. Further decision-making in the pursuit of US residency is influenced by educator training quality, and clinical training and career opportunities. The desire to improve Japanese clinical training commonly influences career decision-making after US training.

Conclusions: The Japanese IMG experience contrasts numerous perceptions of international physician migration and, in turn, enhances understanding of this paradigm.     

Enhancement of reactive oxygen species and induction of apoptosis in streptozotocin-induced diabetic rats under hyperbaric oxygen exposure

An important source of reactive oxygen species (ROS) production is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which on activation induces superoxide production via oxidation in the mitochondria, inflammation and stress; such ROS are implicated in the pathogenesis of diabetic complications, including neuropathy. Hyperbaric oxygen (HBO) treatments are applied various diseases including diabetic patients with unhealing foot ulcers, however, and also increases the formation of ROS. In a previous study, we showed that a clinically recommended HBO treatment significantly enhanced oxidative stress of pancreatic tissue in the diabetic rats. However, no study has been undertaken with regard to the effects of HBO on the activity and gene expression of the NADPH oxidase complex and on apoptosis in the pancreas of diabetic animals. The purpose of this study was to investigate the effect of HBO exposure on gene expression of the NADPH complex, and pancreatic expression of genes related to apoptosis via the mitochondria, using the NADPH oxidase inhibitor apocynin. The mRNA expression of genes related to NADPH oxidase complex and apoptosis increased significantly (P < 0.05) in the pancreas of diabetic rats under HBO exposure. Similarly, activities of NADPH oxidase and caspase-3 changed in parallel with mRNA levels. These results suggest that oxidative stress caused by HBO exposure in diabetic animals induces further ROS production and apoptosis, potentially through the up-regulation of NADPH oxidase complex. Thus, this study can contribute to development of a better understanding of the molecular mechanisms of apoptosis via the mitochondria in diabetes, under HBO exposure.     

The effect of body respirator on the desaturation during the night in Duchenne muscular dystrophy

Recently body respirator (BR) has been used to control respiratory failure in patients with late stage Duchenne muscular dystrophy (DMD). We examined the effect of BR using a pulse oximeter. Arterial oxygen saturation (SaO2) for the night (21:00-7:00) was monitored in 15 DMD patients (5 cases without BR, 3 cases with BR partially for the night and 6 cases with BR all night long) and the desaturation (SaO2 less than 90%) time was followed three times (Jan. '87, Nov. '87, Apr. '88) in each patient. Desaturation time did not increase in 4 cases without BR. But in one case without BR it increased so much that we decided to put the patient on BR. In 3 cases with BR partially for the night, desaturation was well controlled when they used BR. No marked increase of desaturation was found in 4 cases with BR all night long. 2 of these cases were changed from cuirass type BR to jacket type BR and were getting on satisfactorily. Thoracic cage expansion of jacket type was larger than that of cuirass type, and it was found that jacket type was valuable. Also, we investigated the cause of desaturation by recording SaO2, nasal flow, thoracic cage motion and abdominal motion at the same time by making use of a polygraphy. The result showed that the main cause of desaturation was the resistance of thoracic cage motion against BR. And we think research and development is needed.     

Induction of Mucosal B-Cell Memory by Intranasal Immunization of Mice with Respiratory Syncytial Virus

The capacity of live or inactivated respiratory syncytial virus (RSV) to induce B-cell memory in respiratory-associated lymphoid tissues of mice was examined. Eight weeks after primary inoculation with either live or inactivated RSV, adult BALB/c mice were challenged with 4 × 10⁵ PFU of RSV. Protection from viral shedding and mucosal production of RSV-specific antibodies were examined at various time points after challenge. We found that primary immunization with live, but not inactivated, RSV induced complete and durable protection upon challenge within the upper and lower respiratory tract. Also, primary immunization with live, but not inactivated, RSV enhanced the production of mucosal RSV-specific immunoglobulin A (IgA) upon challenge. Secondary mucosal IgA responses were characterized by (i) the early production of mucosal IgA by B cells that reside in organized nasal-associated lymphoid tissues, cervical lymph nodes, and bronchial lymph nodes, and (ii) the subsequent production of RSV-specific IgA by mucosal effector tissues, such as the tracheal lamina propria and lung. These findings suggest that primary infection of mice with live RSV might induce mucosal IgA-committed memory B cells. A greater understanding of the characteristics of RSA-specific mucosal memory B cells may facilitate the development of an RSV vaccine.