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Biomedical subjects

K L Chan

Publications and source records attributed to K L Chan.

At least 109 records · Page 6Linked to original sources
PubMed1998

Successful right trisegmentectomy for ruptured hepatoblastoma with preoperative transcatheter arterial embolization.

This is the first report of the successful use of percutaneous transcatheter arterial embolization (TAE) in controlling hemorrhage from ruptured hepatoblastoma, allowing early major hepatic resection to be performed safely in a young infant. A 6-month-old girl presented with a huge abdominal mass and was found to have a hepatoblastoma that measured 15 x 10 x 12 cm and arose from the right lobe of her liver on computed tomography (CT) scan examination. The tumor spontaneously ruptured, and she went into shock. TAE with gelfoam cube particles successfully arrested the tumor bleeding and allowed stabilization of her blood pressure with blood transfusion. Right trisegmentectomy was performed 12 hours later. The postoperative course was uneventful. With three courses of cisplatin, vincristine, and 5-fluorouracil after the hepatectomy, the serum alpha-fetoprotein level returned to normal, and the patient has remained well 4 months postoperation.

Angiography↗
PubMed1998

Gadolinium-infusion magnetic resonance angiogram: a new, noninvasive, and accurate method of preoperative localization of impalpable undescended testes.

PURPOSE: This study investigates the usefulness of Gadolinium (Gd)-infusion magnetic resonance angiogram (MRA) in the detection of impalpable undescended testes. METHODS: Magnetic resonance (MRI) examination was performed in 14 patients with 17 impalpable undescended testes (unilateral, n = 11; bilateral, n = 3). MRAwasthen performed as follows: Gadolinium-DTPA-BMA (Omniscan) at 0.3 mmol/kg body weight was injected intravenously, and dynamic coronal examination using fast spoiled gradient recalled sequences was obtained with images taken at early arterial and delay venous phases. The testis was located by detection of the enhanced pampiniform venous plexus. RESULTS: Of the 17 undescended testes, 11 canalicular hypoplastic testes and 3 intraabdominal testes were detected in both routine MRI and MRA. Three atrophic testes were found in the scrotum by MRA but not detected by routine MRI. The detection rates of impalpable testes by MRI and MRA were 82.4% and 100%, respectively. All imaging findings were confirmed by surgical exploration. There was no morbidity associated with MRA. CONCLUSION: Gd-infusion MRA is an accurate and sensitive method of preoperative localization of impalpable testes and is superior to conventional MRI in the detection of atrophic testes.

Adolescent↗
PubMed1998

Virtual intraluminal endoscopy: a new method for evaluation and management of choledochal cyst.

A 12-year-old girl who suffered from cholangitis was treated successfully with appropriate antibiotics. She had undergone an operation in mainland China, the exact nature of which was unknown. After an ultrasound study, she underwent a helical computed tomography (CT) cholangiogram using intravenous meglumine iodoxamine. The volume data were transferred to a workstation and virtual endoscopy rendering reconstruction of bile ducts was performed. Findings of this study showed that she had cyst excision with hepaticojejunostomy (HJ), and her intrahepatic ducts were packed with stones. Virtual endoscopy gave the impression that the examiner was flying inside the lumen and showed the stricture at the HJ anastomosis, the inner surface of the bile ducts, areas of dilated intrahepatic ducts, and the intrahepatic stones. The study overcame the need for an invasive study such as a percutaneous transhepatic cholangiography (PTC) and also facilitated appropriate surgical treatment in a timely fashion. It is believed that virtual intraluminal endoscopy (VIE) is helpful in the evaluation and management of selected cases of choledochal cyst.

Anastomosis, Surgical↗
PubMed1998

Segmental small bowel allograft--ischemic injury and regeneration.

PURPOSE: Small bowel transplantation (SBT) is the ultimate treatment for intestinal failure. It remains unclear as to which intestinal segment is more suitable for use in segmental SBT. The current study aims to assess the susceptibility of various parts of small intestine to ischemia and reperfusion injury and their capacity for regeneration. METHODS: Thirty-two segments of pig jejunum and ileum were isolated with intact vascular pedicles that were clamped for periods varying from 1/2 to 8 hours. Biopsy specimens were taken immediately before clamp release and 20 minutes afterwards. All segments were anastomosed together before abdominal closure. Laparotomy was performed 24 hours later, and biopsy specimens were taken at all segments. All specimens were examined histologically by a pathologist. RESULTS: Evidence of injury was detected after 1.5 hours of ischemia at jejunum, but only after 5 hours at ileum. More severe injury was noted at the initial period on reperfusion, but there was no further deterioration at the later period. Complete reepithelialization occurred after 24 hours even where there had been total villous sloughing at reperfusion, but regeneration was impossible when the crypts had been damaged completely. CONCLUSIONS: Ileum, because it is more resistant to ischemia and reperfusion injury, may be preferred for segmental SBT. Regeneration of the bowel epithelium is fast, provided that the crypts are not damaged completely.

Anastomosis, Surgical↗
PubMed1998

Unusual structural abnormality in a biplane transesophageal transducer with normal imaging function.

We encountered a case of an unusual structural abnormality in a biplane transesophageal echocardiography transducer. One of the steel wires making up the flexion cable responsible for anterior flexion was ruptured with one end piercing through the sheath, and this defect did not affect the imaging function of the transducer. Measures to detect this defect should be incorporated into the routine care of the transesophageal transducer.

Echocardiography, Transesophageal↗
PubMed1998

Bioavailability and pharmacokinetics of acyclovir tablet preparation.

The bioavailability of a generic preparation of acyclovir (Avorax) was compared with the innovator product, Zovirax. Twelve healthy volunteers participated in the study, conducted according to a randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration time curve (AUC(0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the Tmax or the logarithmic transformed AUC(0-infinity) and C(max) values of the two preparations. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC(0-infinity) values of Avorax over those of Zovirax was found to lie between 0.85 and 1.06, while that of the logarithmic transformed Cmax values was between 0.95 and 1.25, being within the bioequivalence limit of 0.80-1.25. Moreover, the elimination rate constant (k(e)), elimination half-life (t(1/2)), and apparent volume of distribution (Vd) values obtained with the two preparations were comparable and not significantly different statistically.

Acyclovir↗
PubMed1998

Pharmacokinetic and bioequivalent study of a generic Metoprolol tablet preparation.

A study was conducted to compare the in vivo bioavailability of a generic metoprolol tablet preparation (Metoprolol) with that of the innovator product, Betaloc. Both preparations have a labeled dose of 100 mg metoprolol tartrate. Twelve healthy adult male volunteers participated in the study, which was conducted according to a standard two-way crossover design with a washout period of 1 week. The bioavailability was compared using the total area under the plasma level versus time curve (AUC0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the logarithmically transformed AUC0-infinity values or the logarithmically transformed Cmax values of the two preparations. However, a statistically significant difference was observed between the Tmax values, but may not be therapeutically significant or important. Moreover, the 90% confidence interval (CI) for the ratio of the logarithmically transformed AUC0-infinity values of Metoprolol over those of Betaloc was calculated to be between 0.94 and 1.02, while that of Cmax was between 0.98 and 1.01, both of which are within the acceptable limit of 0.80-1.25. From the data obtained, it was also observed that a high proportion of our volunteers of Asian origin appeared to be poor metabolizers of metoprolol, which was consistent with what had been observed in our previous study of another preparation of metoprolol.

Adrenergic beta-Antagonists↗
PubMed1998

Paediatric liver transplantation: Queen Mary Hospital experience.

OBJECTIVE: To assess the results of paediatric liver transplantation in our institution. METHODS: From September 1993 to November 1996, 10 living-related liver transplants (LRLT) and 3 reduced-size liver transplants (RSLT) were performed on 12 children at our hospital. The medical records of the patients were reviewed. All patients suffered from end-stage liver disease resulting from biliary atresia with failed Kasai's operations. Their ages at initial transplantation ranged from 8 months to 11 years. Excluding the 2 older children aged 7.5 and 11 years, the remaining patients were aged 10.5 months on the average and weighed 6 to 9.5 kg (mean: 6.8 kg) at the time of initial transplantation. RESULTS: All living donors were discharged on postoperative day 4 to 8 and resumed their previous normal activities. All recipients were alive with normal liver function and growing after a follow-up period of 3-40 months (mean: 21 months). The patient survival rate was 100%. One patient with RSLT had hepatitis of undetermined aetiology and underwent retransplant with a graft from her mother. The graft survival rate was 92%. Postoperative complications included: postoperative bleeding (n = 3), hepatic vein stenosis (n = I), biliary-enteric anastomotic stenosis (n = 3), intestinal perforation (n = I) and portal vein thrombosis (n = I). They were all treated promptly. In all patients, the hepatic artery (diameter ranged from 1.5 to 2.5 mm) anastomosis was achieved by microvascular technique. There was no hepatic artery thrombosis in our patients. CONCLUSION: With technical refinements, early detection and prompt treatment of complications, and advances in immunotherapy, excellent results can be achieved in paediatric liver transplantation.

Biliary Atresia↗
PubMed1998

In vitro susceptibility studies of Malaysian Plasmodium falciparum isolates and clones against schizontocidal drugs.

Five Malaysian isolates of the protozoan Plasmodium falciparum Welch were cultured in vitro following the method of Trager and Jensen (1976, 1977) and subsequently cloned using the limiting dilution method of Rosario (1981). Thirty clones were obtained and were later characterized against schizontocidal drugs, chloroquine, mefloquine and quinine, using the modified in vitro microtechnique. Results showed that these local isolates were heterogeneous and most of the clones exhibited similar pattern of susceptibility as their parent isolate except for ST 168 clone and two ST 195 clones that were sensitive but two ST 165 clones, two ST 168 clones and five ST 195 clones were resistant against quinine, respectively. Results also indicated that they were pure clones compared to their parent isolate because their drug susceptibility studies were significantly different (p < 0.05).

Animals↗
PubMed1997

Electrorotation of liposomes: verification of dielectric multi-shell model for cells.

The reliability of multi-shell dielectric models, used to describe the ac electrokinetic behaviour of cells, has been tested by performing electrorotation and dielectrophoretic measurements on unilamellar, oligolamellar, and multilamellar liposomes of diameters ranging from 5 to 24 microm. Fluorescence microscopy, flow cytometry and electron spin resonance were used to characterise the morphology and membranes of the liposomes. The dielectric properties of the various types of liposomes, based on appropriate dielectric shell models, were then analysed using a general purpose, recursive, algorithm. Through simulations, the confidence levels that can be assigned to parameters derived through application of simple shell models are estimated. From this, we confirm that electrorotation data enable accurate determinations to be made of the dielectric properties of the outermost membrane of liposomes, and provide good indications of the level of complexity of the shells and internal compartments. We also demonstrate that, used with sufficient additional information, such as that provided by dielectrophoresis, electrorotation data yields unique solutions for the dielectric parameters of liposome-like particles.

Electric Conductivity↗
PubMed1997

Childhood intussusception: ultrasound-guided Hartmann's solution hydrostatic reduction or barium enema reduction?

A comparison was made of the efficacy of ultrasound guided Hartmann's solution hydrostatic reduction on 23 patients (US group) with the same number of consecutive patients in whom hydrostatic reduction was done by barium enema (BE group) under fluoroscopy for childhood intussusception. The US group was diagnosed by ultrasound scan and reduction was attempted under the guidance of ultrasonography with Hartmann's solution at 100 mm Hg pressure. Excluded were patients older than 12 years, patients in shock, patients with peritonitis, bowel perforation, and gross abdominal distension as well as recurrent intussusception of more than three episodes. There were three patients excluded in this group. The diagnosis of intussusception and complete reduction were confirmed by gastrografin enema. This US group had three recurrences (3 of 26, 11.5%), one lead point (1 of 23, 4.4%), and 19 successful reductions (19 of 26, 73%). Incidentally, there were also three patients excluded in this period of barium enema reduction. There was only one recurrence (1 of 24, 4.2%), one leadpoint (1 of 23, 4.4%), and 12 successful reductions (12 of 24, 50%) in these 23 BE patients. The success rates for the ileo-colic intussusceptions with Hartmann's solution reduction and barium enema reduction were 91% (19 of 21) and 55% (12 of 22), respectively (P = .00865). There was no complication in either group, and the accuracy of diagnosing a complete reduction was 100% in both forms of reduction. Hence, ultrasound-guided hydrostatic reduction for childhood ileocolic intussusception is preferred because it is safe, accurate, has a higher success rate, and can avoid radiation exposure risk.

Barium Sulfate↗
PubMed1997

Liver transplantation in children: the experience of Queen Mary Hospital, Hong Kong.

Seven living-related liver transplants (LRLT) and two reduced-size liver transplants (RSLT) were performed on eight children who suffered from end-stage liver disease, having previously undergone one to three abdominal operations. Their ages at initial transplantation ranged from 8 months to 11 years (mean 35 months, median 12 months). Excluding the two older children aged 7 and 11 years, respectively, the rest of the children weighed 6 to 9.5 kg (mean 7.3 kg) at the time of the initial transplantation. Seven left lateral segments (S2 + 3) and two left lobes (S2 + 3 + 4) were used; of these the smallest graft had a graft-to-recipient body weight ratio of 0.9%. The volunteer living donors were four mothers, two fathers and one sister who were selected after medical and psychiatric evaluations, and their suitability was confirmed by hematological, biochemical, and radiological criteria. During a follow-up period of 3 to 30 months, all eight children are alive and well with normal liver function, one of them having undergone a retransplant LRLT because of hepatitis of undetermined etiology following a RSLT 1.5 years earlier. All seven donors had an uneventful postoperative course and were discharged on day 4 to 7 postoperatively. They have all resumed normal day-to-day activities. There were no complications in the donor group. A variety of complications occurred in the recipients, all of which were overcome. Operating microscope was used to perform all the arterial anastomoses using microvascular techniques. This method has proven to be a major factor in preventing arterial thrombosis even with the smallest of arterial anastomosis where a 1.5-mm diameter recipient artery was anastomosed to a 2.5-mm diameter donor hepatic artery.

Activities of Daily Living↗
PubMed1997

Early and late results of excision of choledochal cysts.

BACKGROUND/PURPOSE: Reports on the late results of choledochal cyst excision with hepaticojejunostomy in children are relatively few. METHODS: Of the 84 patients who had choledochal cyst who came under our care, 79 have had definitive surgery, three are awaiting surgery, one is being observed with Caroli's disease, and the parents of one child have refused surgery. Thirty-eight patients treated decades ago had internal drainage procedures. Since 1972, 41 patients have had cyst excision with hepaticojejunostomy using a 40-cm Roux loop without an antireflux procedure. Early complications in those who underwent cyst excision with hepaticojejunostomy included anastomotic leak in three patients who required reoperation, cholangitis in two, and fluid collection in the gall-bladder bed that required no intervention in one. RESULTS: During a follow-up period ranging from 4 months to 17 years (mean, 8.5 years), anastomotic stricture, cholangitis, and intrahepatic stone formation developed in two children after being well for 8 years and over 11 years. These children required additional surgical procedures to overcome their problems. Asymptomatic intrahepatic stones 2 years after cyst excision with hepaticojejunostomy developed in a third child. There was no mortality in the entire group that underwent cyst excision and they are all enjoying a good quality of life. CONCLUSIONS: Careful, long-term follow-up is important in children who have choledochal cyst excision with hepaticojejunostomy.

Adolescent↗
PubMed1997

Long-term follow-up of childhood duodenal ulcers.

PURPOSE: This study reports the long-term results in children who have duodenal ulcers diagnosed by endoscopy who were treated with H2-receptor antagonist. METHODS: The medical records of 32 children admitted into The Queen Mary Hospital with endoscopically proven duodenal ulcers between 1975 and 1988 were reviewed to evaluate the long-term outcome of childhood duodenal ulcers after initial treatment with H2-receptor antagonist (H2RA). Follow-up details were updated and patients who had been lost to follow-up were recalled. The age of the 22 boys and 10 girls at the time of diagnosis of the ulcers ranged from 3 to 16 years (mean, 11.8 yrs). The duration of follow-up ranged from 8.5 to 21 years (mean, 11.6 yrs). RESULTS: Their primary presentations included epigastric pain (n = 9, 28.0%); nonsteroidal antiinflammatory drug (NSAID)-induced gastrointestinal bleeding (GIB, n = 6, 18.7%); unprovoked GIB (n = 12, 37.5%); perforation (n = 4, 12.5%); and pyloric obstruction (n = 1, 3.0%). All 13 patients who had NSAID-induced ulcers (pain and bleeding) responded to H2RA therapy and required no further treatment. All 14 patients who had unprovoked ulcers who presented with pain or bleeding did not respond to H2RA treatment. Ulcer healing was achieved only after eradication of Helicobacter pylori with antibiotics (n = 8) or definitive surgery involving either truncal vagotomy and pyloroplasty (VP, n = 4) or proximal gastric vagotomy (PGV, n = 2). The patient who had gastric outlet obstruction had vagotomy and antrectomy. All four patients who had perforation were initially treated with patch repair, but two had persistent ulceration despite H2RA treatment and required PGV. Complications developed in none of the four patients who had PGV, whereas two of the four patients with VP had problems (diarrhea, n = 1; bezoar obstruction, n = 1). CONCLUSIONS: Unprovoked childhood duodenal ulcer is associated with significant long-term morbidity and requires continued follow-up. The majority of the ulcers are resistant to H2RA treatment alone and ultimately require either eradication of H. pylori or surgery. In the absence of obstruction, PGV may be enough to resolve the ulcer diathesis.

Adolescent↗