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Biomedical subjects

H T Wong

Publications and source records attributed to H T Wong.

14 recordsLinked to original sources
PubMed2006

Observation of fluorescence emissions from single-bubble sonoluminescence in water doped with quinine.

Sonoluminescence is a phenomenon involving the transduction of sound into light. The detailed mechanism as well as the energy-focusing potentials are not yet fully explored and understood. So far only optical photons are observed, while emissions in the ultra-violet range are only inferred. By doping the fluorescent dye quinine into water with dilute sulphuric acid, the high energy photons can be converted into the optical photons with slower decay constants. These sonoluminescence and fluorescent emissions were observed in coincidence, and the emitted signals of the two modes can be differentiated by their respective timing profiles. Plans for using this technique as a diagnostic tool to quantitatively study ultra-violet and other high energy emissions in sonoluminescence are discussed.

Dose-Response Relationship, Radiation↗
PubMed2005

Intravenous magnesium sulfate to improve outcome after aneurysmal subarachnoid hemorrhage: interim report from a pilot study.

OBJECTIVES: Magnesium sulfate (MgSO4) may be useful in preventing neurological injury after subarachnoid haemorrhage (SAH). In this randomized, double-blind study we evaluated the safety and efficacy of MgSO4 infusion to improve clinical outcome after aneurysmal SAH. METHODS: With ethics committee approval and informed consents, 45 patients with SAH were randomly allocated to receive either MgSO4 80 mmol/day or saline infusion for 14 days. All patients also received intravenous nimodipine. Episodes of vasospasm were treated with hypertensive, hypervolemic therapy. Neurological status was assessed 3 months after haemorrhage using Barthel index and Glasgow outcome scale (GOS). Incidences of cardiac and pulmonary complications were also recorded. Data were compared between groups using Mann-Whitney or Fisher exact tests as appropriate. P < 0.05 was considered significant. RESULTS: Patient characteristics, severity of SAH and surgical treatment did not differ between groups. Although the number of episodes was not reduced, MgSO4 shortened the duration of vasospasm. Patients receiving MgSO4 tended to have fewer neurological deficits, better functional recovery and an improved score in GOS. However, none of these outcome variables reached statistical significance. The incidence of cardiac and pulmonary complications in the MgSO4 group (43%) was also similar to that in the saline group (59%), P = 0.14. CONCLUSIONS: MgSO4 infusion after aneurysmal SAH is well tolerated and may be useful in producing better outcome. A larger study is required to confirm the neuroprotective effect of MgSO4.

Comorbidity↗
PubMed2003

Limit on the electron neutrino magnetic moment from the kuo-sheng reactor neutrino experiment.

A search of neutrino magnetic moment was carried out at the Kuo-Sheng Nuclear Power Station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 kg(-1) keV(-1) day(-1) at 12-60 keV were achieved. Based on 4712 and 1250 h of reactor ON and OFF data, respectively, the limit on the neutrino magnetic moment of mu(nu;(e))<1.3x10(-10)mu(B) at 90% confidence level was derived. An indirect bound of the nu;(e) radiative lifetime of m(3)(nu)tau(nu)>2.8x10(18) eV(3) s can be inferred.

Journal Article↗
PubMed2002

Vertebrobasilar artery dissections: current practice.

Nine patients with vertebrobasilar artery dissections who presented with neurological symptoms or subarachnoid haemorrhage were identified and treated in the Neurosurgical Unit at the Prince of Wales Hospital in Hong Kong. An account of these patients is given and their treatment described. This paper further reviews selected literature to outline the concepts and appropriate management of vertebrobasilar artery dissections.

Adolescent↗
PubMed2001

Three-dimensional virtual-reality surgical planning and soft-tissue prediction for orthognathic surgery.

Complex maxillofacial malformations continue to present challenges in analysis and correction beyond modern technology. The purpose of this paper is to present a virtual-reality workbench for surgeons to perform virtual orthognathic surgical planning and soft-tissue prediction in three dimensions. A resulting surgical planning system, i.e., three-dimensional virtual-reality surgical-planning and soft-tissue prediction for orthognathic surgery, consists of four major stages: computed tomography (CT) data post-processing and reconstruction, three-dimensional (3-D) color facial soft-tissue model generation, virtual surgical planning and simulation, soft-tissue-change preoperative prediction. The surgical planning and simulation are based on a 3-D CT reconstructed bone model, whereas the soft-tissue prediction is based on color texture-mapped and individualized facial soft-tissue model. Our approach is able to provide a quantitative osteotomy-simulated bone model and prediction of postoperative appearance with photorealistic quality. The prediction appearance can be visualized from any arbitrary viewing point using a low-cost personal-computer-based system. This cost-effective solution can be easily adopted in any hospital for daily use.

Humans↗
PubMed2000

Plasmids encoding foot-and-mouth disease virus VP1 epitopes elicited immune responses in mice and swine and protected swine against viral infection.

VP1 is a capsid protein of foot-and-mouth disease virus (FMDV) and contains epitopes of the virus. Plasmids encoding two VP1 epitopes (amino acid residues 141-160 and 200-213) and a host-self immunoglobulin molecule were constructed to produce a new type of FMD DNA vaccine. Two plasmids, namely, pCEIM and pCEIS, containing mouse immunoglobulin (IgG) or swine IgG were subjected to immunogenicity testing in mice and swine, respectively. In mice administrated pCEIM in the abdomen using a genegun, both FMDV-specific T-cell proliferation and neutralizing antibodies were detected. In swine immunized with pCEIS at the back of the ear, immune responses were achieved after the second administration. Swine showed a T-cell proliferative response with a stimulation index (SI) of up to 8.1 and a neutralizing antibody response that was able to protect suckling mice from 10(2) LD(50) (lethal dose 50) FMDV challenge. To compare the immunogenicity of the DNA-based vaccine candidate, versus the protein-based vaccine candidates, a second group of swine was immunized with the protein F1-scIgG, which was encoded by the plasmid pCEIS. Injection with F1-scIgG elicited a T-cell proliferative response of SI < 1.7 and a neutralizing antibody response that protected suckling mice from up to 10(5) LD(50) FMDV challenge. In the challenge test, three of three swine immunized with pCEIS were fully protected from FMDV challenge.

Animals↗
PubMed2000

An immunoglobulin G based chimeric protein induced foot-and-mouth disease specific immune response in swine.

Epitopes containing the residues 141aa-160aa and 200aa-213aa from foot-and-mouth disease (FMD) serotype O1K HK type FMDV VP1 were joined to a swine immunoglobulin G single heavy chain constant region (scIgG), creating a novel chimeric protein, named F1-scIgG. In this study, inoculation with F1-scIgG induced both FMD virus-neutralizing antibody response and T cell response in swine. Antisera from these F1-scIgG-inoculated swine protected suckling mice against 1000 lethal dose 50 (1000LD(50)) FMD challenge. F1-scIgG-inoculated swine were also fully protected against 50LD(50) FMD virus challenge. The present study demonstrates the clear potential for viral epitopes linked with self-Ig in novel FMD vaccine design.

Animals↗
PubMed2000

Comparison of the intraocular pressure-lowering effect of latanoprost and timolol in patients with chronic angle closure glaucoma: a preliminary study.

OBJECTIVE: To compare the intraocular pressure (IOP)-reducing effect and side effects of 0.005% latanoprost once daily to 0.5% timolol twice daily in patients with primary chronic angle closure glaucoma (CACG). DESIGN: Randomized, double-masked two-center clinical trial. PARTICIPANTS: Thirty-two Asian patients with CACG, defined as glaucomatous optic neuropathy with a compatible visual field defect and at least 6 clock hours of synechial angle closure on gonioscopy were recruited. All patients had previous peripheral iridotomy (PI) with IOP >21 mmHg after PI and were thereafter controlled (IOP <22 mmHg) with one or two pressure-reducing drugs. INTERVENTION: After a washout period, the patients were randomized to a 2-week treatment period with either placebo in the morning and 0.005% latanoprost in the evening or 0.5% timolol twice daily. MAIN OUTCOME MEASURES: The short-term IOP reduction of latanoprost and timolol in patients with CACG. IOP was measured at baseline, and after 2, 7, and 14 days of treatment. In addition, the short-term ocular and systemic adverse events of the two drugs were evaluated. RESULTS: Thirty patients completed the study. Two patients in the timolol group were withdrawn because of inadequate IOP control. Compared with baseline, the IOP after 2 weeks of treatment was statistically significantly reduced by 8.8 +/- 1.1 mmHg (mean +/- SEM, P < 0.001) in the latanoprost group, and by 5.7 +/- 0.9 mmHg (P < 0.001) in the timolol group. The difference in IOP reduction between the two treatment groups was 3.1 +/- 1.5 mm Hg in favor of latanoprost (P = 0.04). The main ocular adverse events reported in both treatment groups were conjunctival hyperemia and discomfort. CONCLUSIONS: In this preliminary study, a significantly greater IOP reduction was achieved with 0.005% latanoprost once daily compared with 0.5% timolol twice daily in patients with CACG. The results suggest that latanoprost may be a therapeutic choice for the medical treatment of primary CACG.

Adrenergic beta-Antagonists↗
PubMed2000

Sequence variations of precore/core and precore promoter regions of hepatitis B virus in patients with or without viral reactivation during cytotoxic chemotherapy.

Reactivation of the hepatitis B virus (HBV) is a well-described complication among cancer patients undergoing cytotoxic chemotherapy. Mutations in the preC/C and the preC promoter regions of HBV have been reported in some patients who developed this condition. A G-to-A mutation at nt 1896 in the preC/C region (HBeAg negative/ anti-HBe positive) has been associated with more severe liver disease than that caused by wild type virus. In addition, it has been suggested that patients with these mutations may be more likely to reactivate than those with the wild type virus. Whether or not such mutations were present before the commencement of or developed during the course of cytotoxic chemotherapy is not known. In this study, 28 cancer patients (consisting of 14 consecutive patients who developed HBV reactivation and another 14 who had no reactivation during cytotoxic chemotherapy) are reported. The objectives were firstly, to determine the prechemotherapy HBeAg status and nucleotide sequences of the preC/C and preC promoter regions of HBV in order to determine if these parameters affected the rate of reactivation, and secondly, for those who developed reactivation, to determine whether the mutations were present before chemotherapy or developed during, possibly as a result of, cytotoxic chemotherapy. HBV DNA was amplified by PCR and nucleotide sequencing performed on samples taken prior to chemotherapy and at the time of reactivation. Results revealed that 16 of the 28 patients were HBeAg negative/anti-HBe positive. Of these 16, four (57%) of the seven patients who had nt 1896 mutation, but only one (17%) of the six who had the wild type HBV genome, developed reactivation. Three had no detectable HBV DNA. In the majority of cases, the type of virus, i.e. wild/mutant at preC/C, that was detected during the reactivation was identical to that detected in the pretreatment samples. With respect to the preC promoter region, the two commonest mutations detected were at nt 1762 (A to T) and nt 1764 (G to A). When this region was translated into amino acid sequences, stop codons leading to truncated X protein at carboxyl terminus were found in four patients, three of whom developed HBV reactivation. We conclude that chronic HBV carriers who are HBeAg negative/anti-HBe positive with nt 1896 mutation (G to A) may be more likely to develop HBV reactivation during cytotoxic chemotherapy than those with the wild type virus. Cytotoxic chemotherapy does not appear to select out mutant HBV, or to be consistently mutagenic in patients who develop HBV reactivation. The occurrence of stop codons in the amino acid sequences of the X protein in three patients who developed HBV reactivation, including one who was detected only at the time of reactivation, is of particular interest, as such mutant viruses remain replication competent.

Adult↗
PubMed1999

Augmentation of filtering blebs with perfluoropropane gas bubble: an experimental and pilot clinical study.

OBJECTIVE: To evaluate the use of perfluoropropane (C3F8) gas bubble in the augmentation of glaucoma-filtering blebs. DESIGN: Experimental animal study and a pilot clinical study. PARTICIPANTS: Twenty rabbits in the animal study and 20 humans in the pilot study participated. INTERVENTION: Twenty patients underwent trabeculectomy for medically uncontrolled glaucoma. Surgical techniques were similar to those used in standard limbus-based trabeculectomies. The Tenon's capsule and conjunctival wound were closed separately using continuous sutures. Before the final knots were tied, 0.1 to 0.2 ml of 15%:85%-C3F8:air mixture gas bubble was introduced into the subconjunctival space with a silicone tube attached to a 27-gauge Rycrof cannula. The sutures were immediately knotted on withdrawal of the tube. The patients were reviewed after surgery for the appearance, size, and location of the gas bubble. The bleb morphology and intraocular pressures were also monitored. MAIN OUTCOME MEASURES: The parameters measured were intraocular pressure control, Snellen visual acuity, appearance of the bleb in relation to its elevation and degree of inflammation of the subconjunctival tissue, and characteristics of the gas bubble (e.g., size, number, and position). RESULTS: The gas bubbles stayed in the conjunctival bleb for an average duration of 17 days (range, 13-27 days). In all cases, the gas bubbles helped to maintain the filtering bleb until their complete resolution. No excessive inflammation was noted in the filtering blebs. The mean preoperative intraocular pressure was 27.3 +/- 5.5 millimeters of mercury (mmHg), and the mean postoperative intraocular pressure was 14.5 +/- 2.3 mmHg, with only two patients requiring supplementary topical medication. All cases resulted in good filtering blebs with satisfactory intraocular pressures after 16 months of follow-up. CONCLUSIONS: Subconjunctival C3F8 gas bubbles, via a "spacer" effect, aid the maintenance of filtering blebs in the early postoperative period. This technique may be useful in augmenting or salvaging blebs at risk of failure.

Adult↗
PubMed1999

Genomic cloning and chromosomal localization of the mouse Mab21l2 locus.

A second mouse gene related to the nematode mab-21 gene has been isolated. This gene, Mab21l2, encodes a transcript with an open reading frame discretely organized in a single exon. It shares 93.3% and 55.5% amino acid identity with the human and worm mab-21 respectively. FISH analysis determined that this gene is on chromosome 3 at a position between bands 3E3 and 3F1. This newly identified mouse gene will be useful in future examination of mab-21 gene function in vertebrate models.

Amino Acid Sequence↗
PubMed1995

Venous ligation for cavernous leak impotence--a report on 30 cases.

We report our experience with the surgical treatment of 30 patients with venous leak impotence seen at the Division of Urology, Toa Payoh Hospital, over a period from April 1991 to August 1993. The patients were assessed by history, clinical examination, hormonal evaluation and intracavernosal injection of papaverine. Confirmation of venous leak impotence was obtained by pharmaco-cavernosography in all patients; dynamic cavernosometry was performed in the later part of the series. Surgical treatment consisted of ligation and stripping of the deep dorsal vein, ligation of all its emissary and circumflex tributaries for all patients, with crural plication and suspensory ligament re-approximation in selected patients. Peroperative intracavernosal injection of papaverine was used to identify veins and to assess the adequacy of the extent of venous ligation. The mean age of the patients was 40 years. The average operative time was 2 hours. The usual period of hospitalisation was 3 days. Patients were followed up for an average period of 15.6 months. Success was defined as having adequate erections for normal coitus; the success rates at 1, 3, 6, 9 and 12 months were 76.2%, 61.9%, 52.4%, 42.9% and 38.1%, respectively.

Adult↗
PubMed1979

Microchemical analysis for 13 constituents of plasma from healthy children.

Normal values for 13 chemical constituents of plasma were estimated from results for 837 presumably healthy children. Ninety microliters of specimen was analyzed for lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, inorganic phosphorus, total calcium, total cholesterol, total proteins, albumin, uric acid, urea nitrogen, alanine aminotransferase, total bilirubin, and glucose. We used two Abbott ABA-100 Bichromatic Analyzers interfaced directly to the ABA Data Management System. For each test age- and sex-related variations were assessed and normal values were estimated for six different age groups.

Adolescent↗