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Biomedical subjects

K L Wong

Publications and source records attributed to K L Wong.

At least 19 recordsLinked to original sources
PubMed2003

Isolation and characterization of viruses related to the SARS coronavirus from animals in southern China.

A novel coronavirus (SCoV) is the etiological agent of severe acute respiratory syndrome (SARS). SCoV-like viruses were isolated from Himalayan palm civets found in a live-animal market in Guangdong, China. Evidence of virus infection was also detected in other animals (including a raccoon dog, Nyctereutes procyonoides) and in humans working at the same market. All the animal isolates retain a 29-nucleotide sequence that is not found in most human isolates. The detection of SCoV-like viruses in small, live wild mammals in a retail market indicates a route of interspecies transmission, although the natural reservoir is not known.

Amino Acid Sequence↗
PubMed2003

Determination of the charge state distribution of a highly ionized coronal Au plasma.

We present the first definitive measurement of the charge state distribution of a highly ionized gold plasma in coronal equilibrium. The experiment utilized the Livermore electron beam ion trap EBIT-II in a novel configuration to create a plasma with a Maxwellian temperature of 2.5 keV. The charge balance in the plasma was inferred from spectral line emission measurements which accounted for charge exchange effects. The measured average ionization state was 46.8+/-0.75. This differs from the predictions of two modeling codes by up to four charge states.

Journal Article↗
PubMed2002

Displaced fractures of the hip in children. Management by early operation and immobilisation in a hip spica cast.

Fractures of the hip in children have been associated with a very high rate of serious complications including avascular necrosis (up to 47%) and coxa vara (up to 32%). Over a period of 20 years, we have treated displaced fractures by early anatomical reduction, internal fixation and immobilisation in a spica cast to try to reduce these complications. We have reviewed 18 patients who had a displaced non-pathological fracture of the hip when under 16 years of age. Their mean age at the time of the injury was eight years (2 to 13). They returned for examination and radiography at a mean follow-up of eight years (2 to 17). Each patient had been treated by early (" 24 hours) closed or open reduction with internal fixation and 16 had immobilisation in a spica cast. By Delbet's classification, there was one type-I, eight type-II, eight type-III, and one type-IV fractures. There were no complications in 15 patients. Avascular necrosis occurred in one patient (type-III), nonunion in one (type-II, one of the two patients who did not have a cast) and premature physeal closure in one (type-I). There were no cases of infection or complications as a result of the cast. Our treatment of displaced hip fractures in children by early reduction, internal fixation, and immobilisation in a spica cast gave reduced rates of complications compared with that of large published series in the literature.

Adolescent↗
PubMed2001

Spherical growth and surface-quasifree vibrations of Si nanocrystallites in Er-doped Si nanostructures.

Si-based Er-doped Si nanostructures were fabricated for exploring efficient light emission from Er ions and Si nanocrystallites. High-resolution transmission electron microscopy observations reveal that Si nanocrystallites are spherically embedded in the SiO2 matrix. Energy-dispersive x-ray analysis indicates that the Er centers are distributed at the surfaces of nanocrystallites surrounded by the SiO2 matrix. Low-frequency Raman scattering investigation shows that Lamb's theory can be adopted to exactly calculate the surface vibration frequencies from acoustic phonons confined in spherical Si nanocrystallites and the matrix effects are negligible.

Journal Article↗
PubMed2001

Inhibitory effect of stevioside on calcium influx to produce antihypertension.

Stevioside is a sweet-tasting glycoside occurring abundantly in the leaves of Stevia rebaudiana (Compositae). It has been used popularly in Japan and Brazil as a sugar substitute for decades. Previous study has shown that it lowered blood pressure in spontaneously hypertensive rats (SHRs) when administered intravenously. This study shows that intraperitoneal injection of stevioside 25 mg/kg also has antihypertensive effect in SHRs. In isolated aortic rings from normal rats, stevioside could dose-dependently relax the vasopressin-induced vasoconstriction in both the presence and absence of endothelium. However, stevioside had no effect on phenylephrine- and KCl-induced phasic vasoconstriction. In addition, stevioside lost its influence on vasopressin-induced vasoconstriction in Ca(2+)-free medium. The results indicate that stevioside caused vasorelaxation via an inhibition of Ca(2+) influx into the blood vessel. This phenomenon was further confirmed in cultured aortic smooth muscle cells (A7r5). Using 10(-5) M methylene blue for 15 min, stevioside could still relax 10(-8) M vasopressin-induced vasoconstriction in isolated rat aortic rings, showing that this vasorelaxation effect was not related to nitric oxide. The present data show that the vasorelexation effect of stevioside was mediated mainly through Ca(2+) influx inhibition.

Animals↗
PubMed2001

Complications of thermal capsulorrhaphy of the shoulder.

BACKGROUND: The purpose of this study was to evaluate the rate of recurrence and the prevalence of complications related to the use of thermal energy for the treatment of glenohumeral instability. METHODS: A survey was conducted of all members of the American Shoulder and Elbow Surgeons, the Arthroscopy Association of North America, and the American Orthopaedic Society for Sports Medicine. The survey focused on the rate of recurrence, the number of axillary nerve injuries, and the prevalence of capsular insufficiency seen in revision surgery after thermal capsulorrhaphy of the shoulder. RESULTS: Three hundred and seventy-nine surgeons responded to the survey. Of 236,015 shoulder procedures performed over the last five years, 14,277 (6%) involved the use of thermal energy (1,077 involved laser energy; 9,013, monopolar radiofrequency; and 4,187, bipolar radiofrequency) for the treatment of glenohumeral instability. The rates of recurrent instability after laser, monopolar radiofrequency, and bipolar radiofrequency capsulorrhaphy were 8.4%, 8.3%, and 7.1%, respectively. Of the patients with recurrent instability, 363 (twenty-one treated with laser energy, 220 treated with monopolar radiofrequency, and 122 treated with bipolar radiofrequency) required revision surgery. In this group of patients with revision surgery, seven (33%) of the twenty-one treated primarily with laser energy, thirty-nine (18%) of the 220 treated primarily with monopolar radiofrequency, and twenty-five (20%) of the 122 treated primarily with bipolar radiofrequency exhibited signs of capsular attenuation at the time of the revision. A total of 196 patients (1.4%) (three treated with laser energy; 133, with monopolar radiofrequency; and sixty, with bipolar radiofrequency) had a postoperative axillary neuropathy; 93% of the 196 had a sensory deficit only. Of these patients, 95% recovered completely, with the sensory deficits lasting an average of 2.3 months and the combined deficits, an average of four months. CONCLUSIONS: The use of thermal energy for the treatment of shoulder instability has promising short-term results. The rates of recurrent instability are low. However, when recurrent instability occurs, capsular insufficiency may be present. Axillary nerve injury was reported in 1.4% of the patients, in most of whom it resolved spontaneously.

Adult↗
PubMed2001

Simplified technique to remove posteriorly dislocated lens implants.

Visual loss caused by posterior dislocation of an intraocular lens (IOL) may be managed by placement of a secondary IOL without removal of the dislocated IOL. However, the improved visual acuity may lead to visual disturbances from the mobile, dislocated IOL. Removal of dislocated implants through the pars plana entails risks of a large pars plana incision to include hemorrhage, hypotony, and a greater potential for vitreous traction caused by extraction across the vitreous base. Removal via the corneal limbus lessens these risks but is made more difficult in the presence of a coexisting posterior chamber IOL. The technique reported allows a controlled conversion from posterior to anterior segment surgical techniques that may aid in either the removal or repositioning of posteriorly dislocated lens implants.

Aged↗
PubMed2000

Two-part and three-part fractures: open reduction and internal fixation versus closed reduction and percutaneous pinning.

Surgical management of two-part and three-part proximal humerus fractures is difficult and requires familiarity with more than one method of fixation. Poor bone quality, comminution, and the deforming forces of the rotator cuff on the tuberosities influence the choice of operative approach and fixation techniques. Closed reductions and percutaneous pinning offer the potential advantage of minimal soft-tissue dissection; however, good bone quality and minimal comminution are prerequisites. Selected two-part surgical neck fractures and valgus-impacted fractures lend themselves well to this technique. Open reduction and internal fixation is indicated in two-part surgical neck fractures with poor bone quality or extensive comminution, two-part greater tuberosity or lesser tuberosity fractures, and most three-part fractures. The choice of surgical approach is dictated by the fracture pattern and includes an extended deltopectoral approach and a superior deltoid-splitting approach. Fixation techniques are myriad and are dependent on the fracture pattern. Potential fixation methods include intramedullary rods, interfragmentary sutures or wires, and extramedullary plates and screws or blade plates. Successful results are predicated on obtaining adequate enough fixation to allow early passive motion. Results also are influenced by the quality of the reduction and patient compliance.

Bone Nails↗
PubMed1999

Therapeutic benefits of infrared (810-nm) diode laser macular grid photocoagulation in prophylactic treatment of nonexudative age-related macular degeneration: two-year results of a randomized pilot study.

OBJECTIVE: This pilot study collected preliminary information on the effectiveness and safety of infrared (810-nm) diode laser macular grid photocoagulation in patients with nonexudative age-related macular degeneration (AMD). Results from this pilot study were used in designing a larger, multicenter, randomized clinical trial. DESIGN: A multicenter, randomized, controlled, clinical trial. PARTICIPANTS: A total of 229 eyes of 152 patients with AMD were enrolled in the pilot study. Seventy-five patients with 1 eye eligible (75 eyes) were enrolled in the unilateral arm of the study; 77 patients with both eyes eligible (154 eyes) were enrolled in the bilateral arm of the study. In the unilateral study arm, 32 eyes were randomized to the observation group, 27 eyes were treated with visible endpoint burns, and 16 eyes were treated with invisible endpoint (subthreshold) lesions. In the bilateral study arm, 77 eyes were in the observation group, 36 eyes were treated with visible burns, and 41 eyes were treated with subthreshold (invisible) lesions. INTERVENTION: Eyes were treated with infrared (810-nm) diode laser macular grid photocoagulation using either visible burns or subthreshold (invisible) lesions and compared to eyes receiving no treatment. MAIN OUTCOME MEASURES: Reduction of drusen, change in visual acuity, and rate of choroidal neovascularization (CNV) membrane formation. RESULTS: At 12 months after treatment, 62% of eyes treated with visible burns had a clinically significant reduction in drusen, whereas this proportion (65%) was reached in 18 months for eyes treated with subthreshold lesions. At 24 months' follow-up, treated eyes had a significant reduction in drusen compared to observation eyes (P < 0.0001). Visual acuity was significantly improved in treated eyes at 12, 18, and 24 months compared to observation eyes (P < 0.001). Choroidal neovascularization formation was similar in treated and observation eyes through 24 months' follow-up. Complications included CNV associated with six eyes treated with visible burns and a juxtafoveal laser scar in one eye treated with visible burns. CONCLUSIONS: Infrared (810-nm) diode laser macular grid photocoagulation in patients with nonexudative AMD significantly reduces drusen levels (P < 0.0001) and significantly improves visual acuity (P < 0.001) when either visible endpoint burns or subthreshold endpoint lesions are used. Complications were fewer using subthreshold endpoint lesions. A larger, multicenter, prospective clinical trial with longer follow-up is needed to determine the efficacy of treatment in reducing the rate of CNV formation. Data from this clinical pilot study have been used to design the Prophylactic Treatment of AMD Trial (PTAMD), a multicenter, randomized, prospective clinical trial currently in progress comparing subthreshold (invisible) treatment to observation in eyes with nonexudative AMD.

Aged↗
PubMed1998

Comparison of local infiltration of tenoxicam and intravenous tenoxicam for postoperative analgesia in herniorrhaphy.

BACKGROUND: The major complaint of herniorrhaphy is postoperative pain which occurs during the first 24 h after operation. Tenoxicam has a long half-life of 60-80 h. Local infiltration of the drug concentrates the pain control effects in the local area. The local infiltration dose can be smaller than the recommended systemic dose needfully to reach the target area to be effective. Therefore we studied the effect of preoperative local infiltration of tenoxicam on postoperative pain. METHODS: Sixty patients, belonging to ASA classes I and II, undergoing unilateral herniorrhaphy, were randomly assigned to 4 groups. General anesthesia was induced with thiamylal 5 mg/kg, fentanyl 2 micrograms/kg, and atracurium 5 mg/kg. Group 1 (G1) patients were preoperatively injected with 10 mg of tenoxicam in 10 ml normal saline or distilled water, in the operative area. Group 2 (G2) and Group 3 (G3) patients were preoperatively given intravenous tenoxicam, 20 mg and 10 mg, respectively. Group 4 (G4) patients were not given preoperative local infiltration or intravenous tenoxicam to serve as control group. The pain score was assessed at 2 h, 9 h, 24 h postoperatively in all groups. We recorded the total amount of acetaminophen used and the form of administration of the analgesic drug. All patients received general anesthesia in uniform technique. RESULTS: Pain score and amount of analgesic drug required in G1 (local infiltration group) patients were significantly decreased compared with the other groups. The postoperative pain score of Visual Analog Scale (VAS) and analgesic requirement in the four groups were ranked as follows: G1 < G2 < G3 < G4. No significant difference was observed between G2, G3 and G4. Only the pain score in G2 patients significantly decreased (p < 0.05) during the late postoperative period (24 h) when compared with G4 patients. CONCLUSIONS: Preoperative local infiltration of tenoxicam can decrease postoperative pain score significantly during the most painful period (24 h) in herniorrhaphy.

Adult↗
PubMed1998

Views of obstetric patients who refuse regional anesthesia in cesarean section.

BACKGROUND: Regional anesthesia for cesarean section has gained widespread popularity. However, there are still a good few of obstetric patients who refuse it. This study was to investigate the reasons for refusing regional anesthesia in order to gain some insights into the attitudes and concerns of patients. METHODS: Three hundred and twenty-four obstetric patients scheduled for Cesarean section were interviewed just before entering the operating room. They were asked to give one or two reasons for refusing regional anesthesia. RESULTS: Two hundreds of them refused regional anesthesia. The most frequent reasons were apprehension of witnessing the operation (auditory or visional) (45.42%) and fear of backache following regional anesthesia (14.58%). CONCLUSIONS: Anesthesiologists should be aware of patients' feeling or concern and could be capable and willing to discuss with them the relevant problems.

Adolescent↗
PubMed1997

Development and prospective validation of a clinical index to predict survival in ambulatory patients referred for cardiac transplant evaluation.

BACKGROUND: Risk stratification of patients with end-stage congestive heart failure is a critical component of the transplant candidate selection process. Accurate identification of individuals most likely to survive without a transplant would facilitate more efficient use of scarce donor organs. METHODS AND RESULTS: Multivariable proportional hazards survival models were developed with the use of data on 80 clinical characteristics from 268 ambulatory patients with advanced heart failure (derivation sample). Invasive and noninvasive models (with and without catheterization-derived data) were constructed. A prognostic score was determined for each patient from each model. Stratum-specific likelihood ratios were used to develop three prognostic-score risk groups. The models were prospectively validated on 199 similar patients (validation sample) by calculation of the area under the receiver operating characteristic curve for 1-year event-free survival, the censored c-index for event-free survival, and comparison of event-free survival curves for prognostic-score risk strata. Outcome events were defined as urgent transplant or death without transplant. The noninvasive model performed well in both samples, and increased performance was not attained by the addition of catheterization-derived variables. Prognostic-score risk groups derived from the noninvasive model in the derivation sample effectively stratified the risk of an outcome event in both samples (1-year event-free survival for derivation and validation samples, respectively: low risk, 93% and 88%; medium risk, 72% and 60%; high risk, 43% and 35%). CONCLUSIONS: Selection of candidates for cardiac transplantation may be improved by use of this noninvasive risk-stratification model.

Cardiac Output, Low↗
PubMed1997

Dyspnea resulting from phrenic nerve paralysis after interscalene brachial plexus block in an obese male--a case report.

Phrenic nerve paralysis is a common complication in interscalene brachial plexus block. This complication is often ignored by most anesthesiologists because no clinical symptoms occur in patients who have no underlying lung disease. We present a case of an obese male suffering from dyspnea due to phrenic nerve block after interscalene brachial plexus block. The decreased respiratory reserve and direct compressing effect of the abdominal organs on the diaphragm in the supine position are thought to be the risk factors in this obese patient. Also discussed are the incidence, diagnostic methods, clinical presentation and treatments of phrenic nerve paralysis during interscalene brachial plexus block.

Adult↗
PubMed1996

Effect of celiac ganglionectomy on tachykinin innervation, receptor distribution and intestinal responses in the rat.

Substance P (SP) is an important neurotransmitter in the control of intestinal motility and is found in both the enteric and sympathetic nervous systems. This study examined the effect of celiac ganglionectomy on (1) mechanical properties of the circular muscles of the duodenum, ileum and proximal colon, (2) circular muscle responses to SP and neurokinin A. (3) distribution of substance P-like immunoreactive nerves, and (4) the distribution of neurokinin 1 and neurokinin 2 receptors. Celiac ganglionectomy resulted in an effective sympathectomy as evidenced by a marked decrease in norepinephrine content and tyrosine hydroxylase staining in the duodenum, ileum and proximal colon. The in vitro length/tension characteristics of the circular muscle of the duodenum, ileum and colon were unchanged after ganglionectomy. In all regions of the gut studied, substance P and neurokinin A caused dose-dependent contractions that were unaltered by celiac ganglionectomy. Immunohistochemistry revealed moderate substance P-like immunoreactive fibers in the myenteric plexus, submucosal plexus and circular muscle of the ileum, while in the colon, substance P-like immunoreactivity was intense in the myenteric plexus, and moderate in the circular muscle. In vitro autoradiography showed minimal binding of SP (NK1 receptor) or neurokinin A (NK2 receptor) in the ileum and significantly greater binding in the circular muscle layer of the colon. Celiac ganglionectomy did not affect substance P-like immunoreactivity, or NK1 or NK2 receptor binding. A greater contractile response to neurokinins was seen in the colon than in the duodenum or ileum, which paralleled the receptor density. The studies demonstrate that surgical celiac ganglionectomy, unlike chemical sympathectomy, does not affect the substance P innervation, receptor density or physiological responses of the intestine. The greater contractile response of the colon than the ileum parallels the greater receptor density rather than the peptide content as determined by immunhistochemistry.

Animals↗
PubMed1996

Evaluation of fluorinated indole derivatives for electron-capture negative ionization mass spectrometry: application to the measurement of endogenous 5-methoxyindole-3-acetic acid in rat.

A series of N-trifluoroacetyl/pentafluoropropionyl-O-trifluoroethyl/ pentafluoropropyl/heptafluorobutyl ester derivatives of 5-methoxyindole-3-acetic acid (5MIAA) were synthesized. Under electron-capture negative ionization conditions, the N-trifluoroacetyl derivatives were found to yield relatively abundant, analyte-specific M-. molecular ions and [M-HF]-., [M-HF-CF2CO]-. and [M-CF3CO]- fragment ions, while the N-pentafluoropropionyl derivatives yielded predominantly the reagent-specific pentafluoroacylium C2F5CO- ion. 5-[2H3]Methoxyindole-3-acetic acid was prepared in high yield by a new synthetic procedure and used as the internal standard in subsequent gas chromatographic/mass spectrometric analysis. Using the N-trifluoroacetyl-O-pentafluoropropyl ester derivative, femtomole to low picomole per gland/organ per g ml-1 levels of endogenous 5MIAA were identified and determined in the rat pineal gland, retina, whole brain and serum.

Animals↗