Enhanced performance of a novel anodic PdAu/VGCNF catalyst for electro-oxidation in a glycerol fuel cell.

This study presents a novel anodic PdAu/VGCNF catalyst for electro-oxidation in a glycerol fuel cell. The reaction conditions are critical issues affecting the glycerol electro-oxidation performance. This study presents the effects of catalyst loading, temperature, and electrolyte concentration. The glycerol oxidation performance of the PdAu/VGCNF catalyst on the anode side is tested via cyclic voltammetry with a 3 mm2 active area. The morphology and physical properties of the catalyst are examined using X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Then, optimization is carried out using the response surface method with central composite experimental design. The current density is experimentally obtained as a response variable from a set of experimental laboratory tests. The catalyst loading, temperature, and NaOH concentration are taken as independent parameters, which were evaluated previously in the screening experiments. The highest current density of 158.34 mAcm-2 is obtained under the optimal conditions of 3.0 M NaOH concentration, 60 °C temperature and 12 wt.% catalyst loading. These results prove that PdAu-VGCNF is a potential anodic catalyst for glycerol fuel cells.

Increased production of interferon-gamma by tumour infiltrating T lymphocytes in nasopharyngeal carcinoma: indicative of an activated status.

Undifferentiated nasopharyngeal carcinomas (UNPC) are characterised by an association with Epstein-Barr virus and an abundant lymphoid stroma. We studied the functional status of the infiltrating T cells in ten UNPC biopsies using an immunohistochemical approach. Twelve non-NPC biopsies were included as controls. Tumour cells of UNPC were positive for HLA class I (10/10) and II (8/10), LMP1 (3/10), and CD86 (6/10). Tumour infiltrating T cells (TILs) were detected with antibodies directed at CD3, CD4, and CD8, and shown to be comparable to that in the control biopsies. Although expression of CD28 was shown to be decreased in TILs, expression of CD25 and IFN-gamma at a relatively high percentage could be consistently detected in the UNPC biopsies. These data suggest that TILs in UNPC are in an activated status, and this T cell response is possibly directed at the tumour cells.

Elevated blood levels of soluble tumor necrosis factor receptors in nasopharyngeal carcinoma: correlation with humoral immune response to lytic replication of Epstein-Barr virus.

Nasopharyngeal carcinoma (NPC) is tightly associated with Epstein-Barr virus (EBV) infection and a heavy infiltration of lymphoid cells in the tumor tissue. Although various lines of evidence have shown that the immune systems of NPC patients have the potential to attack the tumor cells, it is not yet understood how this potential is blocked. In this study we determined the circulatory soluble tumor necrosis factor receptors (sTNFRI and sTNFRII), which are proven to be inhibitory to the anti-tumor effects of tumor necrosis factor-alpha (TNF-alpha), in NPC patients. The serum concentration of both sTNFRI and sTNFRII was determined with an ELISA method, and shown to be significantly higher in 28 NPC patients than in matched healthy controls. This elevation was found to be positively correlated with the serum titers of IgA against EBV early antigens and viral capsid antigens in NPC patients, suggesting that the increased serum concentration of sTNFRI and sTNFRII is possibly due to the EBV infection in NPC tumor cells. This is partly supported by FACS analysis of the circulatory T cells. Phenotypical expression of activation markers such as CD25, CD38, CD69 and CD71 in blood T cells was not significantly different between the NPC and control individuals, indicating the elevation of the sTNFRs is indeed derived from the local immune response in the tumor area. Based on these results, it seems that the increased sTNFRs may act as an inhibitor to decrease the host immune response towards tumor cells in NPC patients.

A distinct expression of CC chemokines by macrophages in nasopharyngeal carcinoma: implication for the intense tumor infiltration by T lymphocytes and macrophages.

Nasopharyngeal carcinoma (NPC) is characterized by harboring Epstein-Barr virus genes in the tumor cells and an intense infiltration of leukocytes in the tumor tissue. These infiltrating cells are mainly composed of T lymphocytes and macrophages. The mechanism of this intense infiltration has long been a puzzle. We attempted to address this issue by studying the expression of CC chemokines, which are responsible for recruiting both T cells and macrophages, by an immunohistochemical approach. In biopsies obtained from nasopharynx of 17 NPC patients that contained tumor cells, expression of macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, macrophage chemoattractant protein-1 (MCP-1), MCP-2, MCP-3, and RANTES was detected in the tumor-infiltrating cells, with MIP-1alpha and MCP-1 found in nearly all biopsies and the others relatively less frequently. Furthermore, expression of interferon-gamma (IFN-gamma) was also observed in tumor-infiltrating cells. In contrast, CC chemokines and IFN-gamma were rarely expressed in the 13 control biopsies that were either normal or with nonspecific inflammation, and in 4 biopsies from untreated NPC patients that contained no tumor cells. Using an immunofluorescent double-staining method, MIP-1alpha and MCP-1 were identified to be associated with macrophages, and IFN-gamma with T cells. Moreover, expression of CCR2 and CCR5, the receptors for these chemokines, was also detected in the tumor-infiltrating cells. These data indicate that the intense tumor infiltration by T cells and macrophages is a result of active recruitment. It seems possible that the intense infiltration of leukocytes in NPC tumor tissue is initiated by the activated tumor-reactive T cells. T cells migrate into the tumor tissue in an antigen-specific mode, and IFN-gamma secreted from these pioneer T cells activates tissue macrophages to express CC chemokines, especially MIP-1alpha and MCP-1, which consequently recruit more T cells and macrophages into the tumor tissue.

Complications of foreign bodies in the esophagus.

Major complications of foreign bodies in the esophagus carry significant morbidity and mortality risks. A retrospective case control study was performed to assess the factors associated with major complications. In total, 273 patients seen within a 7-year period were divided into 2 groups; 253 had no or minor complications, and 20 had major complications. Age, sex, duration of the foreign body, total white cell count (TWC), and nature and site of the foreign body were analyzed in the 2 groups. The major complication rate was 7.3%. Duration of the foreign body and TWC were the only statistically significant factors associated with major complications. Six patients required open neck exploration, 1 had an open thoracotomy, and 13 were treated by endoscopic removal. There were 2 deaths. Given the significant morbidity and mortality risks, we conclude that patients with a prolonged history of a foreign body in the esophagus and a raised TWC should be treated urgently.

The role of radiation in delayed hearing loss in nasopharyngeal carcinoma.

Although radiation damage to the inner ear can be induced experimentally in animals, its incidence in humans as a complication of therapy for nasopharyngeal carcinoma (NPC) remains a matter of conjecture due to inadequate histological validation. A case of advanced NPC with a mixed conductive and neurosensory hearing loss is presented that at necropsy showed tumour invasion of the VIIIth cranial nerve in the internal auditory meatus with associated infection. The architecture of the organ of Corti was well-preserved despite heavy doses of radiation but degeneration, the cause of which could not be substantiated, was present in the auditory nerve pathway. A diagnosis of radiation damage to the end-organ of hearing in the absence of supporting histological evidence should be made with caution.

Rhinosporidiosis: an unusual cause of nasal masses gains prominence.

INTRODUCTION: Rhinosporidiosis is a rare cause of nasal masses locally, with only two cases reported over a 35-year period. METHODS: Four patients with rhinosporidiosis, all from the Indian subcontinent, were managed at our tertiary referral centre over a recent five-year period. They presented with nasal masses and the diagnosis was confirmed by histological examination. RESULTS: All patients were treated by local excision of the nasal masses, and two also received dapsone therapy after surgery. During follow-up, local recurrence was found in two patients, one of whom had received dapsone. CONCLUSION: With a significant number of foreign workers from endemic regions, this uncommon disease may be observed more frequently in the future. It is thus important to consider the diagnosis of rhinosporidiosis in patients from endemic regions presenting with nasal masses. The mainstay of treatment should be wide surgical excision.

Subclavian-oesophageal fistula as a complication of foreign body ingestion: a case report.

Foreign bodies in the upper aerodigestive tract are very common. In the local community, the commonest foreign body encountered in the oesophagus is the fish bone. Impaction in the thoracic oesophagus can lead to perforation and the subsequent formation of an arterial-oesophageal fistula. Such fistulae are inevitably aorto-oesophageal in nature. A subclavian-oesophageal fistula is described in this patient.

Otitis externa--the clinical pattern in a tertiary institution in Singapore.

Otitis externa is a common condition in the tropics. Most of the data related to the condition have arisen from Western sources. Locally, the aetiology and the pathogens identified have not been systematically studied. A prospective study involving 107 patients was conducted. Otomycosis was frequently encountered. Coagulase negative Staphylococcus and Aspergillus niger were the most common bacteria and fungus cultured respectively. Gentamicin and polymyxin B were the most effective topical agents against Pseudomonas aeruginosa. Self-cleaning of the ears was the most common predisposing factor.

Use of complementary and alternative medicine in head and neck cancer patients.

OBJECTIVE: To determine the prevalence and profile of patients who use complementary and alternative medicine, within a cohort of head and neck cancer patients. STUDY DESIGN: Cross-sectional survey. SUBJECTS AND METHODS: Ninety-three consecutive head and neck cancer patients being followed up at the department of otolaryngology head and neck surgery were surveyed using an interviewer-administered questionnaire. RESULTS: The prevalence of complementary and alternative medicine use was 67.8 per cent. Patients who used complementary and alternative medicine were more likely to be female, better educated and younger, compared with non-users. A total of 82.5 per cent (52/63) perceived complementary and alternative medicine to be effective, even though they were aware of the lack of research and endorsement by their physician regarding such medicine. CONCLUSION: The use of complementary and alternative medicine by head and neck cancer patients is common, regardless of efficacy or cost. Clinicians should routinely ask patients about their use of complementary and alternative medicine, to facilitate communication and enable appropriate use of such medicine.

Early experience in free tissue transfer in the reconstruction of head and neck defects.

INTRODUCTION: This study aims to retrospectively review our early experience with free tissue transfer in the reconstruction of head and neck defects following extirpation of head and neck cancers in a tertiary hospital in Singapore. METHODS: A total of 25 patients underwent free tissue transfer between June 1998 and Oct 2003. An overall descriptive analysis was carried out by looking at the following outcome measures: length of hospitalisation, duration of intensive care unit (ICU) stay, readmission for complication, and failure rate. RESULTS: There were 21 men and four women in our study cohort, with their age ranging from 28 to 89 (mean 59.8) years. The mean length of stay was 12.6 (SD 7.3) days and mean stay in ICU was 1.6 days. Two patients (8.0 percent) were readmitted within a 30-day period after discharge for flap-related complications. Six patients (24 percent) developed flap-related complications. Two patients developed pharyngocutaneous fistula, three patients developed flap venous congestion and one patient developed minor donor site haematoma. Salvage anastomotic revision was performed in all the three congested flaps. One of the flaps was successfully revived, while the other two flaps were lost. Hence, our flap success rate was 92 percent (23/25). CONCLUSION: Our early experience shows that free tissue transfer is a safe surgical option in the reconstruction of head and neck defects. Our success rate is 92 percent. We believe that subsequent results would continue to improve with advances in technical skill and experience.

Ambulatory thyroid surgery: an audit of safety and outcomes.

INTRODUCTION: Elective hemithyroidectomy is a common operation with a low complication rate. The aim of this study was to conduct an audit on the safety and efficacy of ambulatory hemithyroidectomy in carefully-selected patients. METHODS: This is a cohort study of 114 patients who were scheduled to have either ambulatory (50 patients) or inpatient (64 patients) hemithyroidectomy over a two-year period. Selection for day case surgery was based on pre-established criteria and patient preference. Preoperative patient characteristics, indications for surgery, operative characteristics, histological diagnoses and surgical complications are compared. RESULTS: Of the 50 patients selected for day case surgery, 45 (90 percent) were discharged on the day of surgery. The complication rates of the two groups were similar. Two patients required admission for wound complications and the other three were admitted for non-medical reasons. CONCLUSION: The overall complication rate was low. There were no differences in the rate of complications between ambulatory and inpatient hemithyroidectomies. Ambulatory hemithyroidectomy can be performed safely for a select group of patients in the setting of appropriate facility and management protocol.

Paclitaxel, 5-fluorouracil and hydroxyurea concurrent with radiation in locally advanced nasopharyngeal carcinoma.

BACKGROUND: Concurrent chemoradiotherapy (CRT) is the standard treatment for locally advanced nasopharyngeal carcinoma (NPC). We conducted a phase II trial using paclitaxel, 5-fluorouracil and hydroxyurea concurrent with radiation (TFHX). PATIENTS AND METHODS: Fifty-nine patients with locally advanced NPC were treated with CRT consisting of 4-day continuous infusions of paclitaxel (20 mg/m(2)/d) and 5-fluorouracil (600 mg/m(2)/d), and oral hydroxyurea 500 mg bid for nine doses, every 3 weeks concurrent with radiotherapy (RT). RT consisted of once daily 200cGy fractions 5 times per week to a total of 7000cGy. RESULTS: Complete response was seen in 86% and 71% of patients at 4 and 12 months after CRT. The median follow-up was 34 months. Twenty-three patients experienced relapse. Sixteen deaths occurred: 13 from progressive disease. Three-year overall survival and progression-free survival were 72% and 54% respectively, with locoregional and distant control rates of 83% and 64% at 3 years respectively. Grade 3 to 4 acute toxicities included oropharyngeal mucositis in 81% of patients treated, dermatitis in 63%, weight loss in 32%, and neutropenia in 22%. Neutropenic fever was seen in 14%. There were no treatment-related deaths from acute toxicity. CONCLUSIONS: TFHX is shown to be feasible in NPC. Non-cross resistant induction chemotherapy should be further studied with this regimen.

Celecoxib reduces microvessel density in patients treated with nasopharyngeal carcinoma and induces changes in gene expression.

BACKGROUND: Celecoxib is a selective cyclooxygenase-2 inhibitor with antitumor and antiangiogenic activity. We sought to determine pharmacodynamic change in tumors of patients with nasopharyngeal carcinoma (NPC) treated with celecoxib. METHODS: Tumor biopsies were obtained before and after treatment with celecoxib 400 mg b.i.d. for 14 days in patients with newly diagnosed, untreated NPC. Tumor angiogenesis and cell proliferation were assessed by immunohistochemistry and gene expression by microarray analysis. Plasma celecoxib concentrations were obtained on days 8 and 14. RESULTS: Paired samples were analyzed in 15 patients. Microvessel density was reduced in post-treatment samples and mean celecoxib levels reached therapeutic levels. Thirty-five genes (27 down-regulated, eight up-regulated) were differentially expressed on microarray analysis (p < 0.001). Down-regulated genes included cell cycle regulation-related (cyclin-dependent kinase 2, YES1), transcription factor (TRIP-Br2), whereas the antigen processing and presentation-related gene HLA-DM B was up-regulated. CONCLUSION: Celecoxib reduced angiogenesis and induced tumor transcriptional changes. Further characterization of these transcriptional changes in vivo is needed to provide further insights into the effects of celecoxib in neoplastic tissue. Our findings provide a rationale for clinical studies aimed at assessing the efficacy of celecoxib in the treatment of NPC.

Comparison of histology between recurrent tonsillitis and tonsillar hypertrophy.

To elucidate the aetiology of tonsillar hypertrophy and recurrent tonsillitis, it is important to determine whether a difference exists between these two conditions in microanatomical architecture. The aim of this study was to investigate the difference in follicle size and numbers in tonsils for patients with tonsillar hypertrophy and recurrent tonsillitis using an image analysis method. Our results showed that there was no significant difference in the mean follicle numbers per counting field (40x magnification) between recurrent tonsillitis (4.5 +/- 2.1) and tonsillar hypertrophy (3.8 +/- 0.5). However, the mean follicle area in the tonsillar hypertrophy group (0.23 +/- 0.02 mm2) is significantly (P < 0.01) larger than in the recurrent tonsillitis group (0.15 +/- 0.02 mm2). Our study demonstrates that tonsillar hypertrophy is characterized histologically by an enlargement of follicles compared with chronic tonsillitis, indicating a hyperplastic condition of lymphoid cells in the germinal centres. It may also explain the difference in aetiology and/or immune defence mechanism underlying these two conditions.