Biomedical subjects

J Wong

Publications and source records attributed to J Wong.

At least 37 records · Page 2Linked to original sources

PubMed2006

Comparison of five different abdominal access trocar systems: analysis of insertion force, removal force, and defect size.

Trocar designs have evolved in response to concerns about complication rates and surgical ergonomics. Functional properties of trocar systems that can be objectively measured include insertion force, removal force and the size of the tissue defect. This study will evaluate these properties in 5 common trocar designs. A porcine model was used to evaluate five different trocar systems for insertion force, removal force, and functional and measured tissue defect. Insertion force was lowest for cutting trocars and highest for radially dilating trocars. Removal force was similar for all trocars. Functional and measured tissue defect size was smallest for the hybrid type and radially dilating trocars. An ideal trocar system incorporates a low insertion force, secure retention, and a minimal tissue defect. Of the systems we tested, the hybrid type trocar has similar wound characteristics to the radially dilating trocar with the benefit of reduced insertion force. Further study is required to determine if these properties translate to an actual improvement in patient outcome.

Abdomen↗

PubMed2006

A randomized double blinded study to assess the efficacy of a laser-guided collimator on dental radiography training.

OBJECTIVES: To assess the effect of a laser-guided collimator in intraoral radiography training. METHODS: A custom-made collimator with four red laser diodes on each corner on the rim of an aluminium alloy cubic housing was fabricated. The laser used low power diodes, which are classified as laser-safe by the United States Food and Drug Administration (FDA). When activated, the effective dimensions of the laser beams were 4 cm x 4.5 cm. Eighteen dental hygiene students were randomized into test and control groups. The Laser group used a rectangular collimator with the laser device, while the Non-laser group used a conventional rectangular collimator. Each group attended nine intraoral radiography training sessions. All radiographs were assessed and were classified into three categories: Excellent, Acceptable and Repeat, by a masked academic staff member. Reasons for repeats were marked. Statistical comparisons between the two groups were made. RESULTS: A total of 2334 radiographs were made. Conecut was more common on bitewings than periapicals. The Laser group produced fewer conecuts than the Non-laser group. The Laser group produced more excellent radiographs with fewer repeats than the Non-laser group, but there was not a significant difference. CONCLUSIONS: The laser-guided collimator helped the students to produce fewer repeats in a shorter period of time. It was an effective training aid.

Dental Hygienists↗

PubMed2006

Spontaneous pneumomediastinum in a scuba diver.

Pneumomediastinum usually occurs following an airleak from the lungs, or from a perforated oesophagus. We report on a 30-year-old man who developed pneumomediastinum after scuba diving. The patient presented with acute onset of throat pain, odynophagia, and hoarseness of voice. The literature is reviewed for this condition.

Adult↗

PubMed2006

Fatal septicaemia from Chromobacterium violaceum: case reports and review of the literature.

Chromobacterium violaceum rarely causes infection in humans and its mechanism of pathogenicity is not well understood. Human infection carries a high mortality rate with a fulminating clinical progression. A high index of suspicion is required for diagnosis, and is based on recovering the organisms from blood cultures or other appropriate specimens. We present three cases of human infection managed in a tertiary referral hospital in Hong Kong with a review of the literature.

Adult↗

PubMed2005

Adenosine A2A receptors promote adenosine-stimulated wound healing in bronchial epithelial cells.

Adenosine produces a wide variety of physiological effects through the activation of specific adenosine receptors (A(1), A(2A), A(2B), A(3)). Adenosine, acting particularly at the A(2A) adenosine receptor (A(2A)AR), is a potent endogenous anti-inflammatory agent and sensor of inflammatory tissue damage. The complete healing of wounds is the final step in a highly regulated response to injury. Recent studies on epidermal wounds have identified the A(2A)AR as the main adenosine receptor responsible for altering the kinetics of wound closure. We hypothesized that A(2A)AR promotes wound healing in bronchial epithelial cells (BECs). To test this hypothesis, the human BEC line BEAS-2B and bovine BECs (BBECs) were used. Real-time RT-PCR of RNA from unstimulated BEAS-2B cells revealed transcriptional expression of A(1), A(2A), A(2B) and A(3) receptors. Western blot analysis of lysates from BEAS-2B cells and BBECs detected a single band at 44.7 kDa in both the BECs, indicating the presence of A(2A)AR. In a wound healing model, we found that adenosine stimulated wound repair in cultured BBECs in a concentration-dependent manner, with an optimal closure rate observed between 4 and 6 h. Similarly, the A(2A)AR agonist 5'-(N-cyclopropyl)carboxamidoadenosine (CPCA) augmented wound closure, with a maximal closure rate occurring between 4 and 6 h. Inhibition of A(2A)AR with ZM-241385, a known A(2A)AR antagonist, impeded wound healing. In addition, ZM-241385 also attenuated adenosine-mediated wound repair. Kinase studies revealed that adenosine-stimulated airway repair activates PKA by ligating A(2A)AR. Collectively, the data suggest that the A(2A)AR is involved in BEC adenosine-stimulated wound healing and may prove useful in understanding purinergic-mediated actions on airway epithelial repair.

Adenosine↗

PubMed2005

Clinico-biochemical prediction of biliary cause of acute pancreatitis in the era of endoscopic ultrasonography.

BACKGROUND: Occult biliary stones escape detection on conventional investigations, and clinico-biochemical systems proposed for predicting biliary pancreatitis has low predictive values. AIM: To evaluate the accuracy of clinico-biochemical parameters for prediction of biliary pancreatitis in patients undergoing endoscopic ultrasonography. METHODS: Early endoscopic ultrasonography was performed on 139 patients presenting with acute pancreatitis within 24 h of admission. The aetiologies of all patients were determined after complete evaluations, and clinico-biochemical characteristics of patients with a biliary cause (biliary group) and non-biliary causes (non-biliary group) were compared. RESULTS: Biliary pancreatitis was diagnosed in 107 patients and 32 patients had non-biliary causes. The biliary group belonged to a significantly older age group, had a female predominance, significantly more derangement of liver function and a higher incidence of severe attack of acute pancreatitis. On multivariate analysis, female sex, age >58 years and serum alanine aminotransferase >150 U/L were independent predictive factors for biliary cause of acute pancreatitis. Using these three factors for prediction of biliary cause, the sensitivity was 93% and overall accuracy was 85%. CONCLUSION: Clinico-biochemical prediction for biliary cause of acute pancreatitis improves in the era of endoscopic ultrasonography with a higher sensitivity and overall accuracy. In centres where endoscopic ultrasonography is inaccessible or local expertise is unavailable, clinico-biochemical prediction of biliary cause of acute pancreatitis may provide a useful alternative in the initial management of this group of patients.

Acute Disease↗

PubMed2005

Evaluation of anti-Helicobacter pylori IgG2 antibody for the diagnosis of Helicobacter pylori infection in western and Chinese populations.

BACKGROUND: The performance of commercial Helicobacter pylori diagnostic kits developed for particular geographic regions has often been found to be of poor diagnostic value when applied to other regions, possibly because of infections being caused by different H. pylori strains in different regions. AIM: To evaluate the performance of an IgG2 anti-H. pylori enzyme-linked immunoassay test (Helirad Alert) for detection of H. pylori infection in both Australian and Hong Kong (Chinese) subjects. METHODS: Serum samples were tested for H. pylori specific IgG2 and IgG antibodies by enzyme-linked immunoassay kits using identical antigen preparation in 168 Australian and 160 Hong Kong (Chinese) subjects diagnosed with dyspepsia. RESULTS: Using a cut-off value determined by analysis of H. pylori-negative Australian samples, the sensitivity, specificity and accuracy of the IgG2 assay were 77.8, 97.4 and 91.1%, respectively, for the Australian samples and 96.3, 83.8 and 90% for Hong Kong samples. For the IgG assay, sensitivity, specificity and accuracy were 87.0, 99.1 and 95.2% for Australian samples and 97.5, 75 and 86.3% for Hong Kong samples respectively. Receiver-operating characteristic analysis showed better discrimination of H. pylori status when the IgG2 assay was applied to Hong Kong samples, while the IgG assay was better in the Australian samples. CONCLUSION: These data demonstrate that the Helirad Alert enzyme-linked immunoassay could provide a reliable method for screening H. pylori infection in both western and Chinese populations.

Adult↗

PubMed2005

Brain tissue oxygenation monitoring in acute brain injury.

Cerebral ischemia is one of the most important causes of secondary insults following acute brain injury. While intracranial pressure monitoring in the intensive care unit constitutes the cornerstone of neurocritical care monitoring, it does not reflect the state of oxygenation of the injured brain. The holy grail of neuromonitoring is a modality that would reflect accurately real time the status of oxygenation in the tissue of interest, is robust, artefact free and that which provides information that can be used for therapeutic interventions and to improve outcome. Such a device could conceivably be used to augment the sensitivity of current multi-modality monitoring systems in the neurocritical management of brain injured patients. This article examines the availability of data in the literature to support clinical use of local tissue oxygen probes in intensive care.

Animals↗

PubMed2005

Recruitment of TRADD, FADD, and caspase 8 to double-stranded RNA-triggered death inducing signaling complexes (dsRNA-DISCs).

Rapid elimination of virus-infected cells by apoptosis is an efficient anti-viral strategy. Double-stranded RNA (dsRNA), a viral product, is potently and rapidly apoptogenic in susceptible cells. Caspase 8 plays an important role in the dsRNA-induced apoptosis; however, the mechanisms of caspase 8 activation in response to dsRNA are unknown. We demonstrate here that, in HeLa cells, the dsRNA-triggered activation of caspase 8 is independent of ongoing proteins synthesis (and is, therefore, independent of changes in pro- and anti-apoptotic gene expression) and involves the formation of multiprotein dsRNA-triggered death inducing signaling complexes (dsRNA-DISCs). DsRNA-DISCs contain FADD, TRADD, and caspase 8; however, several experimental approaches suggest that death ligands and death receptors (such as Fas/Apo1 and DR4/Apo2) are not involved in the formation of dsRNA-DISCs.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Inhibition of glycogen synthase kinase 3beta suppresses coxsackievirus-induced cytopathic effect and apoptosis via stabilization of beta-catenin.

Coxsackievirus B3 (CVB3), a common human pathogen for viral myocarditis, induces a direct cytopathic effect (CPE) and apoptosis on infected cells. To elucidate the mechanisms that contribute to these processes, we studied the role of glycogen synthase kinase 3beta (GSK3beta). GSK3beta activity was significantly increased after CVB3 infection and addition of tyrosine kinase inhibitors blocked CVB3-triggered GSK3beta activation. Inhibition of caspase activity had no inhibitory effect on CVB3-induced CPE; however, blockage of GSK3beta activation attenuated both CVB3-induced CPE and apoptosis. We further showed that CVB3 infection resulted in reduced beta-catenin protein expression, and GSK3beta inhibition led to the accumulation and nuclear translocation of beta-catenin. Finally, we found that CVB3-induced CPE and apoptosis were significantly reduced in cells stably overexpressing beta-catenin. Taken together, our results demonstrate that CVB3 infection stimulates GSK3beta activity via a tyrosine kinase-dependent mechanism, which contributes to CVB3-induced CPE and apoptosis through dysregulation of beta-catenin.

Apoptosis↗

PubMed2005

Management of spontaneous perforation of esophageal cancer with covered self expanding metallic stents.

Optimal management of esophageal perforation is controversial, especially in the presence of malignancy. Esophagectomy has traditionally been employed for patients with malignant perforations. However, in patients with advanced disease, other less invasive treatment options may be of benefit. We present two cases of spontaneous perforation of advanced esophageal cancer successfully managed by insertion of covered self-expanding metallic stents and a review of the literature.

Aged↗

PubMed2005

Place(ment) matters: students' clinical experiences and their preferences for first employers.

BACKGROUND: Although a significant volume of nursing research has focused on students' experiences of clinical placements, to date, none has considered these experiences in the context of workforce recruitment and specifically how they may impact upon preferences for working for health care providers. METHODS: In this context, the research used a place-sensitive geographical perspective and a combined questionnaire (n = 650), interview (n = 30) and focus group (n = 7) method to collect data on the complex range of clinical experiences which together impact upon the perceived attractiveness of different health care settings. FINDINGS: The data identified a range of experiential factors associated with mentorship, ward management, learning opportunities and racism. An important finding was that although students' experiences are obtained at the micro ward level, even if they may not necessarily reflect what happens throughout the hospital, they potentially impact, both positively and negatively, upon their broader perceptions of the hospital and the likelihood of seeking work there. IMPLICATIONS: The study highlighted a variety of issues that should be addressed by both higher education institutions and hospitals so that they may be able to provide a more consistent and positive experience for students. In the longer term, this may pay dividends through increased recruitment of new graduates.

Career Choice↗

PubMed2005

Portal vein embolisation prior to extended right-sided hepatic resection.

OBJECTIVES: To determine whether preoperative portal vein embolisation improves the operative outcome of patients undergoing extended right-sided hepatic resection for hepatobiliary malignancy. DESIGN: Prospective non-randomised study. SETTING: University teaching hospital, Hong Kong. PATIENTS: Ninety-two patients underwent extended right-sided hepatic resection for hepatobiliary malignancy during a 45-month period (January 2000 to September 2003). Among them, 15 (16%) underwent portal vein embolisation via a percutaneous ipsilateral approach (n=9) or through the ileocolic vein with a mini-laparotomy (n=6). The remaining 77 (84%) patients underwent hepatic resection without portal vein embolisation. MAIN OUTCOME MEASURES: Operative morbidity and mortality. RESULTS: Patients undergoing portal vein embolisation were older (69 years vs 55 years; P=0.009), and had significantly worse preoperative renal function (creatinine, 96 micromol/L vs 86 micromol/L; P=0.039) and liver function (bilirubin, 23 micromol/L vs 12 micromol/L; P<0.001). Portal vein embolisation resulted in an increase in the future liver remnant of 9% (interquartile range, 7-13%) of the estimated standard liver volume. The operating time for patients receiving portal vein embolisation was significantly longer (medium, 660 min vs 420 min; P<0.001) with more complicated surgery performed in terms of concomitant caudate lobectomy and hepaticojejunostomy. There was no hospital mortality in patients who underwent portal vein embolisation whereas five without the treatment died (P=0.587). The operative morbidity of patients who underwent portal vein embolisation and those who did not was 20% and 30%, respectively (P=0.543). CONCLUSIONS: In older patients who have worse preoperative liver and renal functions, portal vein embolisation enhances the possibility to perform extended right-sided hepatic resection for hepatobiliary malignancies with potentially lower operative mortality and morbidity.

Aged↗

PubMed2005

Intra-arterial thrombolysis for retinal artery occlusion: the Calgary experience.

INTRODUCTION: Retinal artery occlusion represents a medical emergency with poor prognosis for visual recovery. Spontaneous improvement is estimated to occur in less than 15% of central retinal artery occlusion (CRAO) cases and conventional treatments have provided only limited benefit. Intra-arterial thrombolysis has been reported as a potentially efficacious and safe treatment. METHODS: We performed a retrospective chart review of all retinal artery occlusion cases treated with intra-arterial recombinant tissue-type plasminogen activator (rtPA) from January 1998 to May 2004. Patients received Goldmann perimetry visual field testing at a variable interval following the procedure (2 days-2.5 years). Visual acuity (VA) was re-assessed in May 2004. RESULTS: Eight cases (59-77 years) were treated for CRAO, 6-18 hours post-onset with intra-arterial rtPA (10-20 mg over 15-60 minutes); one case of branch occlusion (BRAO) was treated with 30 mg rtPA over 75 minutes, 12 hours post-onset. Among the six patients with CRAO assessed in clinic, three experienced improvement in VA by two or more gradations (Snellen lines); three improved by one gradation. However, none achieved a final VA better than 20/300. The case of branch occlusion improved to a VA of 20/20. All patients had residual monocular field defects. CONCLUSIONS: Our findings reveal a limited benefit for intra-arterial tPA compared to the rate of spontaneous improvement and conventional forms of therapy for retinal artery occlusion.

Adult↗

PubMed2004

Long-term oral branched chain amino acids in patients undergoing chemoembolization for hepatocellular carcinoma: a randomized trial.

BACKGROUND: Patients undergoing transarterial chemoembolization for hepatocellular carcinoma have advanced tumour or severe cirrhosis and frequently have associated protein-calorie malnutrition. The role of nutritional supplements for such patients is unclear. AIM: To investigate, in a randomized controlled trial, any benefit of the long-term administration of branched chain amino acids in patients undergoing chemoembolization for hepatocellular carcinoma. METHODS: Forty-one patients received oral branched chain amino acids for up to four courses of chemoembolization and 43 patients did not receive any nutritional supplement. Morbidity, liver function, nutritional status, quality of life and long-term survival were compared between the two groups. RESULTS: The administration of branched chain amino acids resulted in a lower morbidity rate compared with the control group (17.1% vs. 37.2%, P = 0.039). In particular, the group given branched chain amino acids showed a significantly lower rate of ascites (7.3% vs. 23.2%, P = 0.043) and peripheral oedema (9.8% vs. 27.9%, P = 0.034). Significantly higher serum albumin, lower bilirubin and a better quality of life were observed after chemoembolization in the group given branched chain amino acids. However, there was no significant difference in survival between the two groups. CONCLUSIONS: Nutritional supplementation with oral branched chain amino acids is beneficial in increasing the serum albumin level, reducing the morbidity and improving the quality of life in patients undergoing chemoembolization for inoperable hepatocellular carcinoma.

Adult↗

PubMed2004

Workshop on partial breast irradiation: state of the art and the science, Bethesda, MD, December 8-10, 2002.

Breast conserving surgery followed by radiation therapy has been accepted as an alternative to mastectomy in the management of patients with early-stage breast cancer. Over the past decade there has been increasing interest in a variety of radiation techniques designed to treat only the portion of the breast deemed to be at high risk for local recurrence (partial-breast irradiation [PBI]) and to shorten the duration of treatment (accelerated partial-breast irradiation [APBI]). To consider issues regarding the equivalency of the various radiation therapy approaches and to address future needs for research, quality assurance, and training, the National Cancer Institute, Division of Cancer Treatment and Diagnosis, Radiation Research Program, hosted a Workshop on PBI in December 2002. Although 5- to 7-year outcome data on patients treated with PBI and APBI are now becoming available, many issues remain unresolved, including clinical and pathologic selection criteria, radiation dose and fractionation and how they relate to the standard fractionation for whole breast irradiation, appropriate target volume, local control within the untreated ipsilateral breast tissue, and overall survival. This Workshop report defines the issues in relation to PBI and APBI, recommends parameters for consideration in clinical trials and for reporting of results, serves to enhance dialogue among the advocates of the various radiation techniques, and emphasizes the importance of education and training in regard to results of PBI and APBI as they become emerging clinical treatments.

Breast Neoplasms↗

PubMed2004

Influence of laparoscopy on postoperative recurrence and survival in patients with ruptured hepatocellular carcinoma undergoing hepatic resection.

BACKGROUND: Use of laparoscopy in patients with gastrointestinal cancer has been associated with port-site and peritoneal tumour metastases. The effect of laparoscopy on tumour recurrence and long-term survival in patients undergoing resection of ruptured hepatocellular carcinoma (HCC) remains unknown. METHODS: Between June 1994 and December 2001, 59 patients with ruptured HCC underwent surgical exploration with a view to hepatic resection. Laparoscopy with laparoscopic ultrasonography was performed in 33 patients; the other 26 patients underwent exploratory laparotomy without laparoscopy. Perioperative and long-term outcomes were compared between the two groups. RESULTS: Exploratory laparotomy was avoided in 12 of 13 patients with irresectable HCC who had a laparoscopy. The hospital stay of these 12 patients was significantly shorter than that of eight patients found to have irresectable HCC at exploratory laparotomy (median 11 versus 15 days; P = 0.043). Twenty patients had a laparoscopy followed by open resection of HCC, whereas 18 patients underwent laparotomy and resection without laparoscopy. There were no significant differences in disease-free (16 versus 19 per cent; P = 0.525) and overall (32 versus 48 per cent; P = 0.176) survival at 3 years between the two groups. The tumour recurrence pattern was similar between the two groups, and there were no port-site or wound metastases. CONCLUSION: Use of diagnostic laparoscopy in patients with ruptured HCC helps avoid unnecessary exploratory laparotomy. The present data suggest that laparoscopy does not have an adverse effect on tumour recurrence or survival in patients who undergo resection.

Adult↗

PubMed2004

Delayed portal vein thrombosis after experimental radiofrequency ablation near the main portal vein.

BACKGROUND: Portal venous blood flow may protect adjacent tumour cells from thermal destruction with radiofrequency ablation (RFA). This study aimed to investigate the local effect of RFA on the main portal vein branch, and the completeness of cellular ablation in its vicinity, with or without a Pringle manoeuvre using a porcine model. METHODS: This was an in vivo study on 23 domestic pigs. RFA using a cooled-tip electrode was performed 5 mm from the left main portal vein branch under ultrasonographic guidance for 12 min with (n = 10) or without (n = 10) a Pringle manoeuvre. Ten pigs were killed 4 h after the procedure to study the early effects of RFA and ten others were killed 1 week later to determine any delayed effect. As a control, sham operations with a Pringle manoeuvre for 12 min were performed on three pigs. The flow velocity changes of portal vein and hepatic artery were measured using Doppler ultrasonography, and the completeness of cellular ablation around the portal vein was assessed qualitatively by histochemical staining and quantitatively by measuring intracellular levels of adenosine 5'-triphosphate (ATP). RESULTS: In the absence of the Pringle manoeuvre, there was no significant change in mean(s.d.) portal vein flow velocity before RFA (20.0(3.5) cm/s) and at 4 h (18.5(2.5) cm/s) (P = 0.210) and 1 week (19.5(2.2) cm/s) (P = 0.500) after the procedure. Gross and histological examination of the portal vein branches showed no damage without the Pringle manoeuvre. In all pigs that underwent RFA with a Pringle manoeuvre, the portal vein was occluded 1 week after the operation; histological examination of the affected portal vein showed severe thermal injury and associated venous thrombosis. The local effect of RFA on the hepatic artery was similar. With intact portal blood flow during RFA, complete ablation of liver tissue around the pedicle was demonstrated by histochemical staining and measurement of the intracellular ATP concentration. CONCLUSION: RFA was safe when applied close to the main portal vein branch without a Pringle manoeuvre, with complete cellular destruction. Use of the Pringle manoeuvre resulted in delayed portal vein and hepatic artery thrombosis and injury to the hepatic artery and bile duct.

Animals↗