High-peak-power optically pumped passively mode-locked semiconductor laser with minimal components.

A high-peak-power sub-500-fs mode-locked optically pumped semiconductor laser is innovatively developed with only three components of a semiconductor gain chip, a semiconductor saturable absorber, and a focusing lens. The developed laser near the threshold pump power of 3.9 W can be operated with stable fundamental mode locking. The laser output can be naturally turned into the stable harmonic mode locking (HML) with the order gradually changing from 2nd to 8th by increasing the pump power from 4.0 W to 5.0 W. Due to the onset of the high-order transverse modes, the order of HML is fixed at 8th for a pump power greater than 5.0 W. For the HML with order less than 8th, the overall peak power and pulse width in the HML are approximately 0.36 kW and 550 fs, respectively. In the operation of 8th-order HML, the minimum pulse width and maximum peak power can reach 480 fs and 0.95 kW, respectively.

Burnout and well-being in young doctors in Hong Kong: a territory-wide cross-sectional survey.

INTRODUCTION: This territory-wide study evaluated the level of burnout and health status among young doctors in Hong Kong. METHODS: All young doctors in Hong Kong, defined as residents-in-training or doctors within 10 years of their specialist registration, were invited to participate in an online cross-sectional survey. This survey used standardised questionnaires including the Copenhagen Burnout Inventory (CBI) for burnout, Patient Health Questionnaire-9 for depression, and general health questionnaires. RESULTS: In total, 514 doctors completed the survey; 284 were doctors within 10 years of their specialist registration, while 230 were residents-in-training. There were 277 women (54%); among all respondents, the mean age was 33.7 ± 6.1 years. Using a CBI subscale cut-off score of ≥50 (moderate and higher), 72.6% (n=373) of respondents reported personal burnout; 70.6% (n=363) of respondents reported work-related burnout; and 55.4% (n=285) of respondents reported client-related burnout. Furthermore, 24% (n=125) of respondents were "somewhat dissatisfied" with their present job position; 4% (n=19) of respondents were "very dissatisfied" with their present job position. The prevalence of depression among respondents was 21% (n=110). CONCLUSIONS: In this territory-wide cross-sectional survey of young doctors in Hong Kong, a high prevalence of burnout was identified among young doctors; respondents exhibited a considerable level of depression and substantial dissatisfaction with their current positions. Strategies to address these problems must be formulated to ensure the future well-being of the medical and dental workforce in Hong Kong.

Reduction of postural nasal resistance following oropharyngeal surgery in patients with moderate-severe obstructive sleep apnea.

BACKGROUND: Patients with obstructive sleep apnea (OSA) have elevated nasopharyngeal resistances due to increased turbulent airflow. The study aims to investigate the effect of oropharyngeal surgery on nasal resistance in patients with various severity levels of OSA. METHODOLOGY: Patients with greater or equal to 5 events hourly on the apnea-hypopnea index (AHI) were enrolled. Patients with retropalatal obstruction underwent uvulopalatopharyngoplasty, while patients with concurrent retrolingual obstruction under- went uvulopalatopharyngoplasty (UPPP) plus tongue base suspension. Before surgery and after surgery, subjective outcomes were assessed using a visual analog scale (VAS), and objective outcomes were assessed using overnight polysomnography and rhinomanometry. The limitation of the study was that UPPP instead of expansion sphincter pharyngoplasty was performed in this study. RESULTS: Sixty-two patients were enrolled, while 30 patients were diagnosed as mild OSA (group Mild) and 32 patients were mo- derate-severe OSA (group MS). The preoperative VAS of nasal obstruction in recumbency during sleep was significantly reduced after surgery in group MS. However, no significant differences between preoperative and postoperative VAS were found in group Mild. The postoperative anterior and posterior total nasal resistances (TNR) in sitting and supine positions were not significantly different from those before surgery in group. In contrast, the postoperative posterior TNR in supine position was 0.292±0.301(Pa/ cm3/s), compared with 0.425±0.343(Pa/cm3/s) preoperatively. CONCLUSIONS: Oropharyngeal surgery improves nasal obstruction during sleep and lowers the supine TNR measured in poste- rior rhinomanometry in patients with moderate-severe OSA. Oropharyngeal surgery is a possible treatment for postural nasal obstruction in patients with moderate-severe OSA.

Prognostic impact of pre-treatment neutrophil-to-lymphocyte ratio (NLR) in nasopharyngeal carcinoma: A retrospective study of 180 Taiwanese patients.

OBJECTIVES: Nasopharyngeal cancer (NPC) is an endemic disease in Taiwan. Prognostic factors the anatomical TNM stage are important for its prognostic stratification. An elevated neutrophil-to-lymphocyte ratio (NLR) has been reported to be associated with poor prognosis in various solid tumours. In this study, we analysed the prognostic impact of the NLR in NPC in Taiwan. DESIGN: Single-institution retrospective study. SETTING: Medical centre. PARTICIPANTS: One hundred and eighty patients with NPC treated at the Far Eastern Memorial Hospital, Taiwan, from January 2007 to December 2013. MAIN OUTCOME MEASURES: The association between the clinical or haematological presentations and the prognosis. RESULTS: The majority of the 180 patients included in this study were men (80%) and were <65 years old (91.7%). A neck mass (55.6%) was the most common clinical presentation, followed by nasal (39.4%) and aural (30.6%) symptoms. In addition, the majority (75.4%) of patients had advanced stage (III and IV) disease. Patients with a high NLR (≧3.6) had significantly lower progression-free survival, overall survival and disease-specific survival rates. The association between high NLR and poor prognosis was more pronounced in patients with advanced disease than in those with early-stage NPC. The results of a multivariate analysis revealed that advanced age, clinical symptoms including headache, diplopia and facial numbness, advanced disease stage, and high NLR were independent prognostic factors. CONCLUSION: A high NLR is an independent poor prognostic factor of NPC in Taiwan.

A real-time prediction model for post-irradiation malignant cervical lymph nodes.

OBJECTIVE: To establish a real-time predictive scoring model based on sonographic characteristics for identifying malignant cervical lymph nodes (LNs) in cancer patients after neck irradiation. METHODS: One-hundred forty-four irradiation-treated patients underwent ultrasonography and ultrasound-guided fine-needle aspirations (USgFNAs), and the resultant data were used to construct a real-time and computerised predictive scoring model. This scoring system was further compared with our previously proposed prediction model. RESULTS: A predictive scoring model, 1.35 × (L axis) + 2.03 × (S axis) + 2.27 × (margin) + 1.48 × (echogenic hilum) + 3.7, was generated by stepwise multivariate logistic regression analysis. Neck LNs were considered to be malignant when the score was ≥ 7, corresponding to a sensitivity of 85.5%, specificity of 79.4%, positive predictive value (PPV) of 82.3%, negative predictive value (NPV) of 83.1%, and overall accuracy of 82.6%. When this new model and the original model were compared, the areas under the receiver operating characteristic curve (c-statistic) were 0.89 and 0.81, respectively (P < .05). CONCLUSIONS: A real-time sonographic predictive scoring model was constructed to provide prompt and reliable guidance for USgFNA biopsies to manage cervical LNs after neck irradiation.

Effects of comorbidity and medication use on the haemodynamic status during office-based laryngeal procedures: A prospective cohort study.

OBJECTIVE: Office-based laryngeal procedures (OBLPs) are emerging as effective alternative modalities for vocal disorders. This study systematically investigates the haemodynamic status of patients, specifically focusing on the potential effects of underlying comorbidity and medication use. DESIGN: Prospective cohort study. SETTING: Tertiary referral centre. PARTICIPANTS: We prospectively recruited 214 consecutive patients who received OBLPs during January-December 2015. All procedures were performed under local anaesthesia without sedation, in an upright (sitting) position. MAIN OUTCOME MEASURES: We measured heart rate (HR), systolic and diastolic blood pressure, and oxygen saturations at baseline (before procedure), immediately after local anaesthesia to the pharynx and larynx, immediately after completing of procedure, and 20 minutes after the procedure. RESULTS: Systolic, diastolic blood pressures and HR all significantly increased after local anaesthesia, and gradually decreased after the procedure (P<.01). Oxygen concentration remained unchanged. Patients with comorbidity and those receiving vasoactive medications showed significantly higher perioperative blood pressures than the other patients (P<.05), but the trend remained similar. Prominent hypertension (systolic ≥160 mm Hg or diastolic ≥100 mm Hg) was noted in 17 patients, more commonly in patients with older age, higher baseline blood pressures and receiving vasoactive medications. Only 2% of patients with normal baseline measurements developed prominent hypertension perioperatively. Tachycardia (HR≥100 bpm) developed in 22 patients, more frequently in patients with higher baseline HRs, and perceiving greater discomforts. CONCLUSION: This study revealed that routine haemodynamic monitoring may not be necessary for all the OBLPs, but should be considered for older patients, those with higher baseline blood pressure or HR, sensitive patients who might be more susceptible to perioperative discomfort, and those receiving vasoactive medications.

Involvement of two distinct signalling pathways in IGF-1-mediated central control of hypotensive effects in normotensive and hypertensive rats.

AIMS: Insulin-like growth factor-1 (IGF-1) is abundantly expressed in the nucleus tractus solitarii (NTS). In a previous study, we revealed that the induction of nitric oxide (NO) production in the NTS reduces blood pressure (BP). It is well known that both acute administration and chronic administration of IGF-I reduce BP. The aim of this study was to evaluate the short-term hypotensive effect of IGF-1 in the NTS and to delineate the underlying molecular mechanisms of IGF-1 in the NTS of normotensive WKY rats and spontaneously hypertensive rats (SHRs). METHOD: Microinjections of the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and the MAP kinase-ERK kinase (MEK) inhibitor PD98059 into the NTS in WKY rats and SHRs were used to study the involvement of IGF-1-induced depressor effects. RESULT: An IGF-1 (7.7 pmol) injection into the NTS resulted in a significant decrease in BP and HR in WKY rats and SHRs. Immunoblotting and immunohistochemical analysis showed that the microinjection of LY294002 (0.6 pmol) or PD98059 (3.0 pmol) into the NTS attenuated the IGF-1-induced depressor effects and Akt or ERK phosphorylation in WKY rats. An attenuation effect of LY294002, but not PD98059, was found in the SHRs. However, the mRNA and protein expression levels of the IGF-1R showed no significant differences in the NTS of the WKY rats and the SHRs. CONCLUSION: These results suggest that distinct Akt and ERK signalling pathways mediated the IGF-1 control of the central depressor effects in WKY rats and SHRs. ERK signalling defects may be associated with the development of hypertension.

Three-dimensional analysis of the surface registration accuracy of electromagnetic navigation systems in live endoscopic sinus surgery.

BACKGROUND: Studies on the performance of surface registration with electromagnetic tracking systems are lacking in both live surgery and the laboratory setting. This study presents the efficiency in time of the system preparation as well as the navigational accuracy of surface registration using electromagnetic tracking systems. METHODOLOGY: Forty patients with bilateral chronic paranasal pansinusitis underwent endoscopic sinus surgery after undergoing sinus computed tomography scans. The surgeries were performed under electromagnetic navigation guidance after the surface registration had been carried out on all of the patients. The intraoperative measurements indicate the time taken for equipment set-up, surface registration and surgical procedure, as well as the degree of navigation error along 3 axes. RESULTS: The time taken for equipment set-up, surface registration and the surgical procedure was 179 +- 23 seconds, 39 +- 4.8 seconds and 114 +- 36 minutes, respectively. A comparison of the navigation error along the 3 axes showed that the deviation in the medial-lateral direction was significantly less than that in the anterior-posterior and cranial-caudal directions. CONCLUSION: The procedures of equipment set-up and surface registration in electromagnetic navigation tracking are efficient, convenient and easy to manipulate. The system accuracy is within the acceptable ranges, especially on the medial-lateral axis.

Dose-dependent effects of D-methionine for rescuing noise-induced permanent threshold shift in guinea-pigs.

The purpose of this study was to examine the dose-response effectiveness of d-methionine (d-met) in rescuing a noise-induced permanent threshold shift (PTS) and cochlear biochemistry following noise exposure. One hour after being exposed to continuous broadband white noise at 105dB sound pressure level (SPL) for 6h, guinea-pigs were treated five times at 12-h intervals with 200, 400, or 600mg/kg d-met or sterile 0.9% saline (each group, N=6) by intraperitoneal injection. Six guinea-pigs with normal hearing that were not exposed to noise served as control animals. Although administration of d-met 200mg/kg did not significantly reduce the mean PTS, treatment with d-met 600mg/kg achieved a complete rescue response. The level of rescue from noise-induced PTS following treatment with 200, 400, or 600mg/kg d-met was dose dependent. The attenuation of the noise-induced decreases in the activities of the Na(+), K(+)-ATPase and Ca(2+)-ATPase following treatment with 200, 400, or 600mg/kg d-met was also dose dependent. Likewise, d-met-dose-dependent decreases in mean lipid peroxidation and nitric oxide levels were observed in the d-met treated groups. Significant attenuation of increased oxidative stress and decreased ATPase activities was concurrent with the d-met-mediated improvements in noise-induced auditory dysfunction.

Angioplasty and stenting for intracranial atherosclerotic stenosis: position statement of the Hong Kong Society of Interventional and Therapeutic Neuroradiology.

As a means of preventing secondary ischaemic stroke, angioplasty and stenting are considered potentially beneficial for patients with severe intracranial atherosclerotic stenosis. However, the role of stenting has been challenged since the publication of the first randomised controlled trial on Stenting versus Aggressive Medical Management for Preventing Recurrent stroke in Intracranial arterial Stenosis (SAMMPRIS). This indicated that aggressive medical management was superior to stenting using Wingspan to prevent recurrent stroke, because stenting has a high peri-procedural stroke and death rate. In this paper, we review the management of intracranial atherosclerosis, revisit the skepticism on stenting, and state our position on the topic in the form of recommendations. These are based on the prevalence of the disease in Hong Kong, the high risk of recurrent stroke despite medical therapy in the presence of haemodynamic intracranial stenosis without sufficient collaterals, an analysis of the weak points of SAMMPRIS, and results of clinical studies in Hong Kong.

Isolated adult Langerhans' cell histiocytosis in cervical lymph nodes: should it be treated?

OBJECTIVE: We report an extremely rare case of Langerhans' cell histiocytosis involving isolated cervical lymph nodes, and we discuss the diagnosis and treatment of this infrequent disease. METHOD: We present a case report and literature review concerning this disease entity. RESULTS: A 54-year-old man presented with persistent, multiple, left neck masses. Histopathological study of lymph node specimens showed proliferation of Langerhans' cells coupled with eosinophilic and neutrophilic microabscesses. Positive immunohistochemical staining for Cluster of Differentiation 1a (CD1a) in Langerhans' cells confirmed the diagnosis. No other abnormalities were noted on a series of image studies. The patient was managed with 'watchful waiting' without subsequent therapy. The neck lesions regressed gradually over time, and the patient did well over a two-year follow-up period. CONCLUSION: The clinical presentation of Langerhans' cell histiocytosis is highly variable, and the choice of treatment depends on the involved organs. Definitive diagnosis depends on identification of characteristic immunohistochemical or ultrastructural features of the biopsy specimen. Watchful waiting may be an effective management strategy in cases of adult isolated lymph node Langerhans' cell histiocytosis, due to its possible spontaneous regression.