Topological edge plasmon modes between diatomic chains of plasmonic nanoparticles.

We study the topological edge plasmon modes between two "diatomic" chains of identical plasmonic nanoparticles. Zak phase for longitudinal plasmon modes in each chain is calculated analytically by solutions of macroscopic Maxwell's equations for particles in quasi-static dipole approximation. This approximation provides a direct analogy with the Su-Schrieffer-Heeger model such that the eigenvalue is mapped to the frequency dependent inverse-polarizability of the nanoparticles. The edge state frequency is found to be the same as the single-particle resonance frequency, which is insensitive to the separation distances within a unit cell. Finally, full electrodynamic simulations with realistic parameters suggest that the edge plasmon mode can be realized through near-field optical spectroscopy.

Twists and turns in the body: an imaging spectrum.

Life is full of twists and turns. These surprises can sometimes be wonderfully invigorating. Twists and turns can also occur in the body, however, sometimes with dangerous consequences. Torsion and volvulus are important causes of acute abdominal pain. The clinical symptoms and signs associated with torsion and volvulus are often non-specific and are difficult to diagnose clinically. Clinicians frequently rely on imaging methods to make the diagnosis. Prompt and accurate diagnosis is important to avoid the life-threatening complications of torsion and volvulus. Therefore, it is helpful to be familiar with the features of torsion and volvulus.

Cholecystectomy or not after percutaneous cholecystostomy for acute calculous cholecystitis in high-risk patients.

BACKGROUND/AIMS: This study aims to evaluate the outcomes of percutaneous cholecystostomy for acute calculous cholecystitis in patients with high surgical risk and determine whether subsequent cholecystectomy is beneficial and necessary. Percutaneous cholecystostomy has been shown to be a safe treatment option for patients suffering from acute cholecystitis but at high risk for emergency surgery. Controversies still exist on the approach of the cholecystostomy and the subsequent management of these patients. METHODOLOGY: From January 1996 to March 2004, percutaneous cholecystostomy was performed on 65 patients that suffered from acute calculous cholecystostomy but were considered high risk for emergency surgery (American Society of Anesthesiologists grade III or IV). Their clinical outcomes were described and risk factors for in-hospital mortality and recurrence of cholecystitis were identified by univariate and multivariate analysis. RESULTS: Percutaneous cholecystostomy was successfully performed in all patients (100%). The clinical response rate was 91%. The in-hospital mortality was 12.3%. Shock on admission was found to be a single independent risk factor for in-hospital death (p=0.006; odd ratio = 16.5; 95% CI = 2.2-123.1). Twenty-four patients underwent subsequent cholecystectomy whereas 33 did not. The 1-year and 3-year recurrence of acute cholecystitis were 35% and 46% respectively in patients who did not have subsequent cholecystectomy. Stone size > or = 1cm was independently associated with higher recurrence of acute cholecystitis (p=0.01; hazard ratio = 6.3, 95% CI 1.6-25.5). However, there was no difference in 1-year and 3-year overall survival between patients with or without cholecystectomy (82% Vs 81% and 59% Vs 63%, p=0.79). CONCLUSIONS: Percutaneous cholecystostomy is a safe and promising treatment for acute calculous cholecystitis in patients who are at high risk for emergency surgery. Cholecystectomy after the resolution of cholecystitis and optimization of associated medical illnesses is always advisable in order to prevent recurrent cholecystitis. However, the limited survival of these patients because of their old age and medical co-morbidities should be taken into consideration.

Bleeding pseudoaneurysms complicating upper abdominal surgery.

OBJECTIVE: To review the management of ruptured pseudoaneurysms following upper abdominal surgery. DESIGN: Retrospective study. SETTING: Minimal access surgery centre, Hong Kong. PATIENTS: Patients who were diagnosed to have a pseudoaneurysm after undergoing major upper abdominal surgery were recruited during the period of 1998 to 2006. MAIN OUTCOME MEASURES: Success rate of haemostasis, re-bleeding rate, re-intervention rate, and mortality. RESULTS: During the study period, a total of eight patients (median age, 61 years) were managed in our department for bleeding pseudoaneurysms following cholecystectomy, gastrectomy, or Whipple's operation. Five patients underwent upper endoscopy as the initial investigation. In four of these five patients, visceral artery pseudoaneurysms were identified by angiography and haemostasis was achieved without re-bleeding. The one for whom angiographic identification of the bleeding source failed, was successfully treated subsequently by open plication. In three other patients, open surgical haemostasis was resorted to and achieved in two of them. However, one of the latter had re-bleeding, which was successfully treated by embolisation. The one who failed open identification of the bleeding source, was eventually also treated successfully by embolisation. The overall success rates of embolisation and open surgery were 80% and 67%, respectively, and the re-bleeding rates were 0% and 33%, respectively. The corresponding mortality rates were 20% and 33%; both deaths were associated with multi-organ failure. There were no procedure-related complications following embolisation. CONCLUSIONS: Based on our experience, visceral angiography can enable the diagnosis and treatment of ruptured pseudoaneurysm in a single session. The procedure is safe, the re-bleeding rate is low, and it is as effective as alternative treatments, and should be considered a first-line intervention in patients with bleeding pseudoaneurysms complicating upper abdominal surgery.

Evidence of cisplatin-induced senescent-like growth arrest in nasopharyngeal carcinoma cells.

Cellular senescence is a programmed cell response leading to growth arrest in human diploid fibroblasts. We have shown that a nasopharyngeal carcinoma cell line, CNE1, following treatment by the DNA-damaging agent cisplatin, can undergo cellular senescent-like growth arrest, similar to fibroblasts, judged by cellular morphological changes and the expression of senescence-associated beta-galactosidase (SA-beta-gal). This senescent-like change was dose related; at 0.5 microgram/ml, the percentage of cisplatin-induced SA-beta-gal-positive cells was high (40-96%), and the staining was intense. Higher doses (1.0 and 2.0 micrograms/ml) of cisplatin induced lower SA-beta-gal expression (30-70%), and the process was irreversible. This cisplatin-induced cellular senescent-like response was not due to the inhibition of telomerase activity. Our results indicate that cellular senescent-like pathways exist in nasopharyngeal carcinoma cells and can be induced by cisplatin. Our evidence suggests that cellular senescent-like responses may be a cellular protection mechanism that acts differently in response to different degrees of cellular damage.

Atypical manifestations in a patient with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a chronic systemic inflammatory disease associated with the production of various autoantibodies and involvement of multiple organs. Necropsy findings in a 65 year old woman with SLE who had multiple aortic aneurysms and dissections, as well as other unusual manifestations, are described. The case illustrates the occurrence of and the difficulties encountered in the diagnosis of several diseases, namely aortic aneurysm, aortic dissection, acute pancreatitis, and Penicillium marneffei infection.

Tension pneumocephalus--a rare complication of radiotherapy in nasopharyngeal carcinoma.

A patient with nasopharyngeal carcinoma (NPC) treated by radiotherapy developed tension pneumocephalus due to a naso-cranial fistula. The fistula was due to a pathological fracture at the base of skull affected by bone necrosis. The clinical features, neuro-radiological and post-mortem findings are presented. This is the first case report of pneumocephalus in association with NPC. The brain showed florid subarachnoid and intraventricular air collection under tension, low grade meningitis, foreign body giant cell reaction in the arachnoid membrane and multifocal cerebral infarction. Late radiation necrosis was also found in the left temporal lobe. The cause of the tension pneumocephalus in relation to radiation bone necrosis and the possible role of pneumocephalus in producing the multifocal cerebral infarction are discussed. The more common radiation necrosis of brain is also discussed. The pathogenesis of the pneumocephalus in this patient is distinctly different from the more common causes such as head injury and surgery.

Outpatient laparoscopic cholecystectomy in Hong Kong: patient acceptance.

The authors performed a prospective evaluation of 60 Hong Kong Chinese patients with symptomatic gallstones and gallbladder polyps undergoing outpatient laparoscopic cholecystectomy in a regional hospital in Hong Kong from March 1996 to May 1998 to determine the feasibility, satisfaction, and acceptance of this procedure among Chinese patients. Patients with American Society of Anesthesiologists grade I and II gallstones or polyps were selected. Exclusion criteria included 1) history of upper abdominal operations, attacks of acute cholecystitis, cholangitis, or pancreatitis; 2) abnormal liver function; and 3) ultrasonographic evidence of contracted gallbladder, thickened gallbladder wall, dilated common bile duct, or common bile duct stones. Patients discharged at 5:00 PM on the day of cholecystectomy were defined as having undergone outpatient procedure. Patients were asked about procedure acceptance, rated on a scale of 1 to 10 (best), using a standardized questionnaire 4 weeks after operation. The study included 21 men and 39 women with mean age of 40.5 years (range, 27-59). There were no conversions to open procedures in the series. There were 6 (10%) unanticipated postoperative hospital admissions; all patients were discharged on the first postoperative day. Another patient was readmitted 3 days after operation because of a common bile duct stone. Overall patient acceptance of outpatient laparoscopic cholecystectomy was good, with a mean score of 8.6 of 10. Thirteen patients (22%) expressed dissatisfaction with being discharged earlier than they had expected, and 9 (15%) would have preferred inpatient care. Forty-eight patients (80%) resumed full daily activities by the first postoperative day; the remaining 12 did so by the end of the first week. Among the 44 working patients, only 4 (9%) resumed full duty within the first postoperative week; 29 (66%) did so by the second week and the remaining 11 (25%) returned to work after the third week. By selecting appropriate subjects, outpatient laparoscopic cholecystectomy is feasible and highly accepted among Hong Kong Chinese patients. Approximately one quarter of the patients preferred a longer postoperative stay or inpatient care.

Accuracy and efficiency of X-ray requests initiated by triage nurses in an accident and emergency department.

A study was carried out from 1 March 1995 to 31 March 1995 in the Accident & Emergency department, Pamela Youde Nethersole Eastern Hospital, Hong Kong. The aim was to assess the feasibility of requesting X-rays by triage nurses based on a pre-set protocol prior to patients being seen by a doctor. Judgement of the attending physician was used as the gold standard by which to judge the need for radiographs requested by the triage nurse. In addition, the senior medical officer or consultant would judge whether the triage nurse had applied the protocol correctly. A total of 934 patients were included in the study and 883 (94.54%) patients had X-rays requested by the triage nurse. Only 5.44% of the radiographs requested by nurses were considered to haven been unnecessary by the doctor. There was no statistically significant difference in agreement for the child and adult groups. In 917 (98%) of cases, nurses had adhered to the protocol. A saving of an average of 18.59 minutes of total service time was obtained during the study. Requesting of X-ray by triage nurse was feasible

Combined percutaneous and endoscopic approach in management of dropped gallstones following laparoscopic cholecystectomy.

Dropped gallstones due to accidental perforation of gallbladder wall during laparoscopic cholecystectomy are often encountered. However, dropped gallstones as nidus of infection with subsequent abscess formation is a rare complication of laparoscopic cholecystectomy (0.3%). Most of the reported cases of complicated dropped stones required open surgical drainage. Minimally invasive measures were less frequently employed. We report a case of dropped gallstones that were removed endoscopically through a percutaneous drainage tract.

Trace gas detection by laser intracavity photothermal spectroscopy.

A novel laser intracavity photothermal detector is described. In this scheme, sample absorption of the pump laser power takes place within the cavity of a probe He-Ne laser causing modulation in the gain and in turn the output power. Comparison of this intracavity detector with two other photothermal techniques, namely, phase fluctuation optical heterodyne spectroscopy and thermal beam deflection, is made in terms of practicality and sensitivity. For in situ measurements, sensitivity of 0.5 x 10(-7) cm(-1) for a probe length of 3 cm has been achieved.

Influence of saline media on the fluorescence emission of Bacillus spores.

Single-particle levitation in conjunction with 264.3-nm laser excitation is used to measure the fluorescence emission of individual particles of Bacillus globigii spores. With precise humidity control, the fluorescence emission of wetted and desiccated Bacillus spore particles is measured from 300 to 450 nm. Comparison of spectra for Bacillus spores suspended in a standard buffer aqueous solution and for a desiccated 10-mum-diameter aggregate Bacillus spore particle shows that the spectra is virtually indistinguishable. However, at 85% relative humidity, corresponding to a 4.5M sodium chloride solution, the spore spectra redshifts by approximately 25 nm. It is postulated that the spectra redshifting is a result of specific interactions between the tyrosine fluorophore of the Bacillus spore and the phosphate moieties in the buffer solution.

Study of condensational growth of water droplets by Mie resonance spectroscopy.

An optical technique using MIE resonance scattering spectroscopy to monitor the growth of a saline solution droplet is presented. This technique utilizes a quadrupole particle trap to suspend a charged NaCl solution droplet in a water vapor environment and a CO(2) laser to momentarily perturb the droplet-vapor equilibrium. The condensational growth of this droplet is monitored by means of multiple Mie resonances observed at right angle scattering. A least-squares fit, used to evaluate the condensation coefficient of water, shows that the value tends to approach unity. In addition, this new approach reduces the error in dry salt size measurement to <1%.

Fine-needle aspiration in hepatocellular carcinoma. Combined cytologic and histologic approach.

Cytologic features of fine-needle aspiration (FNA) of hepatocellular carcinoma (HCC) have not been well documented. Most previous reports described only the the morphologic features of the tumor cells without considering the sinusoidal stroma. Cytohistologic correlation on tissue from the same aspirate has rarely been done. This report describes the cytologic patterns of 50 cases of HCC in terms of histologic pattern observed in cell blocks prepared from the same aspiration specimen and classified according to the World Health Organization (WHO) classification. Tumors were classified according to the predominant pattern. Thirty-two cases gave the trabecular pattern. Smears could be subdivided into a central-sinusoidal pattern (23 cases) and a peripheral-sinusoidal pattern (nine cases). One case gave the pseudoglandular pattern. Seventeen cases gave the compact pattern with inconspicuous sinusoids. In all cases sinusoids were easily recognized in cell block sections. Other cytologic features such as intranuclear cytoplasmic inclusions, eosinophilic globules, and bile secretion could be seen in both smears and cell blocks. Mallory's hyalin and ground glass inclusions were only recognized in cell blocks. More attention should be paid to the sinusoidal stroma for diagnosis of HCC in FNA; cell blocks should be more widely utilized to this effect; cytologic patterns could be classified according to the WHO histologic classification.

A retrospective review of transcatheter hepatic arterial embolisation for ruptured hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is a disease with a high prevalence in South East Asia. It is not uncommon to encounter rupture of the tumour in an emergency situation. Operative measures in this situation are often associated with high mortality rates. Transcatheter arterial embolisation (TAE) appears to be an effective alternative to surgery and is increasingly used by many centres. In this study, we have reviewed the outcome of our patients after receiving TAE and tried to identify prognostic indicator(s). PATIENTS AND METHODS: From 1996 to 2000, we had retrospectively reviewed the outcome of 31 patients who had undergone TAE for rupture of HCC and compared their survival with respect to different prognostic indicators. RESULTS: The were 31 patients with a mean age of 53 years. At the time of rupture, 19 patients had Child's A, 5 Child's B and 7 of Child's C disease. The most common presentation was abdominal pain (14 patients). Bleeding was successfully arrested in all 31 patients. The most common complication was fever (13 patients). The overall mean survival was 126 days. Eight patients died within 30 days of admission, the major cause of death was liver failure, which occurred in 6 patients. In addition, we had also postulated several prognostic indicators for patients' survival. The results showed that only those with a bilirubin level below 50 umol/L and who presented with shock had a poor outcome. CONCLUSION: TAE should be considered in the initial management of patients with ruptured HCC. It is effective in arresting tumour bleeding and allows the patient to have subsequent definitive management.

High-resolution CT findings in patients with severe acute respiratory syndrome: a pattern-based approach.

OBJECTIVE: We retrospectively reviewed high-resolution CT (HRCT) examinations of the lungs performed in 27 confirmed cases of severe acute respiratory syndrome (SARS). The HRCT findings at different phases of the illness were analyzed. CONCLUSION: A defined pattern of HRCT findings is observed in different phases of SARS, which is characterized by focal ground-glass and crazy paving patterns in a scattered distribution at presentation, followed by development of interstitial thickening, consolidation, pleural reaction, and scarring. Spontaneous pneumomediastinum is a distinct complication during the course of the illness.