Parametrically Tunable Soliton-Induced Resonant Radiation by Three-Wave Mixing.

We show that a temporal soliton can induce resonant radiation by three-wave mixing nonlinearities. This constitutes a new class of resonant radiation whose spectral positions are parametrically tunable. The experimental verification is done in a periodically poled lithium niobate crystal, where a femtosecond near-IR soliton is excited and resonant radiation waves are observed exactly at the calculated soliton phase-matching wavelengths via the sum- and difference-frequency generation nonlinearities. This extends the supercontinuum bandwidth well into the mid IR to span 550-5000 nm, and the mid-IR edge is parametrically tunable over 1000 nm by changing the three-wave mixing phase-matching condition. The results are important for the bright and broadband supercontinuum generation and for the frequency comb generation in quadratic nonlinear microresonators.

Diagnosis and surgical outcomes of intraparotid facial nerve schwannoma showing normal facial nerve function.

The findings of intraparotid facial nerve schwannoma (FNS) using preoperative diagnostic tools, including ultrasonography (US)-guided fine needle aspiration biopsy, computed tomography (CT) scan, and magnetic resonance imaging (MRI), were analyzed to determine if there are any useful findings that might suggest the presence of a lesion. Treatment guidelines are suggested. The medical records of 15 patients who were diagnosed with an intraparotid FNS were retrospectively analyzed. US and CT scans provide clinicians with only limited information; gadolinium enhanced T1-weighted images from MRI provide more specific findings. Tumors could be removed successfully with surgical exploration, preserving facial nerve function at the same time. Gadolinium-enhanced T1-weighted MRI showed more characteristic findings for the diagnosis of intraparotid FNS. Intraparotid FNS without facial palsy can be diagnosed with MRI preoperatively, and surgical exploration is a suitable treatment modality which can remove the tumor and preserve facial nerve function.

Low dose of gamma irradiation enhanced boronophenylalanine uptake in head and neck carcinoma cells for boron neutron capture therapy.

This study attempted to increase the boron uptake of human head and neck carcinoma SAS cells for BNCT by using a gamma dose of 0.1 Gy for combined treatment. Intracellular boron concentrations in 25 µgB/mL medium of BPA treated and BPA combined gamma-irradiation treated SAS cells were 73.8±1.73 and 95.15±1.36 ppm, respectively. After neutron irradiation, the G2/M-phase cell populations of untreated, BPA treated and BPA combined gamma-irradiation treated SAS cells were 19.31±1.71%, 52.47±2.25% and 59.19±2.63%, respectively. Experimental results indicate that the low dose gamma radiation with combination BPA treatment has the highest killing rate after neutron irradiation. Capable of significantly increasing the G2/M arrest after neutron irradiation, the combined treatment of a low dose of gamma irradiation with 25 µg B/mL medium of BPA also provided a higher killing effect for BNCT.

Telephone pre-anaesthesia assessment for ambulatory breast surgery.

OBJECTIVE: To review the efficacy of telephone preoperative anaesthesia assessment in patients undergoing ambulatory breast surgery. DESIGN: Retrospective study. SETTING: Day Surgery Centre, Tung Wah Hospital, Hong Kong. PATIENTS: Patients with breast lumps to be excised were seen by dedicated breast surgeons and informed of day procedures and preoperative anaesthesia assessment. Those who fulfilled the selection criteria of age (18-45 years) and American Society of Anesthesiologists grade I were recruited for telephone anaesthesia assessment preoperatively. The patients were contacted by senior day surgery nurses via telephone before the scheduled operation date, and information was retrieved using a standard assessment form. Prospective data from January 2002 to December 2007 were analysed. MAIN OUTCOME MEASURES: Proportion of patients who successfully underwent day surgery after telephone preoperative anaesthesia assessment. RESULTS: Of 482 patients receiving ambulatory surgery for breast lumps during the study period, 283 patients were selected for preoperative telephone anaesthesia assessment. Five (2%) patients with problems identified by this method underwent further assessment at the Day Surgery Centre; the remaining 278 (98%) required no further assessment and proceeded to have a successful day surgery procedure. CONCLUSION: Preoperative anaesthesia assessment by telephone is an effective means of preoperative assessment in selected patients undergoing ambulatory breast surgery.

Suitability of boron carriers for BNCT: accumulation of boron in malignant and normal liver cells after treatment with BPA, BSH and BA.

Hepatocellular carcinoma remains widely prevalent in tropical Africa and south-east Asia. At present, there are no effective treatments for hepatoma and its prognosis is extremely poor unless the tumor was diagnosed in an early stage and resected before metastasis. Therefore, boron neutron capture therapy (BNCT) may provide an alternative therapy for treatment of hepatocellular carcinoma. In this study, the intracellular concentrations of L-boronophenylalanine (BPA), sodium borocaptate (BSH) and boric acid (BA) were examined in human hepatoma HepG2 and liver Clone 9 cell cultures. With the use of 25 microgB/mL media of BPA, BSH and BA, the intracellular uptake of boron in HepG2 and Clone 9 cells was compared. The suitability of BPA, BSH and BA were further evaluated on the basis of organ-specific boron distribution in normal rat tissues. BPA, BSH and BA were administered via intraperitoneal injection into rats with corresponding boron concentrations of 7, 25, and 25mg/kg body weight, respectively. The accumulation rates of BPA, BSH and BA in HepG2 cells were higher than that of Clone 9 cells. Boron concentration in BPA, BSH and BA treated HepG2 cells were 1.8, 1.5, and 1.6-fold of Clone 9 cells at 4h, respectively. In both HepG2 and Clone 9 cells, although the concentration of boron in BPA-treated cells exceeded that in BA-treated ones, however, cells treated with BPA had similar surviving fraction as those treated with BA after neutron irradiation. The accumulation ratios of boron in liver, pancreas and kidney to boron in blood were 0.83, 4.16 and 2.47, respectively, in BPA treated rats, and 0.75, 0.35 and 2.89, respectively, in BSH treated rats at 3h after treatment. However, boron does not appear to accumulate specifically in soft tissues in BA treated rats. For in situ BNCT of hepatoma, normal organs with high boron concentration and adjacent to liver may be damaged in neutron irradiation. BPA showed high retention in pancreas and may not be a good drug for BNCT of hepatoma. BSH had higher retention in liver but low level in pancreas and spleen appears to be a better candidate BNCT drug for hepatoma. These preliminary results provide useful information on future application of BNCT for hepatoma.