Spontaneous formation of boron nitride nanotube fibers by boron impurity reduction in laser ablation of ammonia borane.

Highly crystalline and few-walled boron nitride nanotubes (BNNTs) had been synthesized by laser ablation using only ammonia borane as a precursor. As a molecular precursor, ammonia borane supplied both B and N atoms with a ratio of 1:1, and BNNTs were formed via the homogeneous nucleation of BN radicals, not the growth from boron nano-droplets, which is a generally accepted growth mechanism of the laser-grown BNNTs. Owing to the absence of amorphous boron impurities, the van der Waals interaction among BNNTs became effective and thus a BNNT fibers was formed spontaneously during the BNNT synthesis. The BNNT growth and the subsequent fiber formation are found to occur only at high pressures of a surrounding gas. The mechanism behind the critical role of pressure was elucidated from the perspective of reaction kinetics and thermal fluid behaviors. A polarized Raman study confirmed that the BNNT fiber formed exhibits a good alignment of BNNTs, which implies great potential for continuous production of high-quality BNNT fibers for various applications.

Safety and tolerability of intradiscal implantation of combined autologous adipose-derived mesenchymal stem cells and hyaluronic acid in patients with chronic discogenic low back pain: 1-year follow-up of a phase I study.

BACKGROUND: Adipose tissue-derived mesenchymal stem cells (AT-MSCs) offer potential as a therapeutic option for chronic discogenic low back pain (LBP) because of their immunomodulatory functions and capacity for cartilage differentiation. The goal of this study was to assess the safety and tolerability of a single intradiscal implantation of combined AT-MSCs and hyaluronic acid (HA) derivative in patients with chronic discogenic LBP. METHODS: We performed a single-arm phase I clinical trial with a 12-month follow-up and enrolled 10 eligible chronic LBP patients. Chronic LBP had lasted for more than 3 months with a minimum intensity of 4/10 on a visual analogue scale (VAS) and disability level ≥ 30% on the Oswestry Disability Index (ODI). The 10 patients underwent a single intradiscal injection of combined HA derivative and AT-MSCs at a dose of 2 × 107 cells/disc (n = 5) or 4 × 107 cells/disc (n = 5). Safety and treatment outcomes were evaluated by assessing VAS, ODI, Short Form-36 (SF-36), and imaging (lumbar spine X-ray imaging and MRI) at regular intervals over 1 year. RESULTS: No patients were lost at any point during the 1-year clinical study. We observed no procedure or stem cell-related adverse events or serious adverse events during the 1-year follow-up period. VAS, ODI, and SF-36 scores significantly improved in both groups receiving both low (cases 2, 4, and 5) and high (cases 7, 8, and 9) cell doses, and did not differ significantly between the two groups. Among six patients who achieved significant improvement in VAS, ODI, and SF-36, three patients (cases 4, 8, and 9) were determined to have increased water content based on an increased apparent diffusion coefficient on diffusion MRI. CONCLUSIONS: Combined implantation of AT-MSCs and HA derivative in chronic discogenic LBP is safe and tolerable. However, the efficacy of combined AT-MSCs and HA should be investigated in a randomized controlled trial in a larger population. TRIAL REGISTRATION: ClinicalTrials.gov NCT02338271 . Registered 7 January 2015.

Clinical characteristics and determinants of exercise-induced pulmonary hypertension in patients with preserved left ventricular ejection fraction.

AIMS: Recent studies have shown that exercise-induced pulmonary hypertension (EIPH) is not rare in patients with preserved left ventricular ejection fraction (LVEF). However, the determinants and clinical implication of EIPH in these patients are unclear. METHODS AND RESULTS: This study included 1383 patients who were referred for exercise echocardiography to evaluate unexplained exertional dyspnoea or chest discomfort. Pulmonary artery systolic pressure (PASP) was estimated from the maximal velocity of the tricuspid regurgitant jet added to a right atrial pressure of 10 mmHg. EIPH was defined as PASP ≥50 mmHg during exercise. The EIPH group consisted of about one-third of all patients (436 patients, 31.5%). Patients with EIPH were older, more commonly male and had shorter exercise times. In resting echocardiographic findings, the patients with EIPH had worse diastolic function associated with a lower e' value (7.0 ± 2.0 vs. 7.5 ± 2.3 cm/s, P< 0.001), a longer deceleration time (238.9 ± 54.9 vs. 232.8 ± 46.0 ms, P= 0.043), and a higher E/e' ratio (10.1 ± 2.9 vs. 9.1 ± 2.7, P< 0.001) compared with those without EIPH. In multivariable analysis, age (P< 0.001), resting E/e' ratio (P< 0.001), and resting PASP (P< 0.001) were identified as independent determinants of EIPH. CONCLUSION: EIPH was documented in one-third of patients with preserved LVEF. Age, resting E/e' ratio, and resting PASP were independently associated with EIPH. Therefore, EIPH should be considered as a cause of unexplained exercise intolerance in patients with preserved LVEF.

A case report of paraneoplastic pemphigus associated with esophageal squamous cell carcinoma.

Paraneoplastic pemphigus is an autoimmune blistering and erosive mucocutaneous syndrome associated with underlying neoplasm. It is primarily associated with lymphoproliferative disorders, and uncommonly with malignancies of epithelial origin. We report on a case of a 68-year-old male who presented with whole body bullous and erosive skin lesions. Findings on upper gastrointestinal endoscopy and skin biopsy revealed esophageal squamous cell carcinoma and paraneoplastic pemphigus. Palliative chemotherapy and systemic glucocorticoid were started, however, the patient died of overwhelming sepsis on the ninth day of chemotherapy. This case demonstrates that paraneoplastic pemphigus can occur in esophageal squamous cell carcinoma and could be a cause of morbidity.

A case of swallow syncope associated with cold beverage ingestion.

Swallow syncope (also known as deglutition syncope) is a relatively rare type of syncope that is treatable if diagnosed correctly. We report a case of a 39-year-old man with recurrent swallow syncope. The patient did not have structural heart disease. He developed a complete atrioventricular block upon drinking a cold beverage (Chilsung cider) while undergoing a repeated head-up tilt test. The patient was advised to avoid cold beverages and has been symptom free for 5 months.