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Biomedical subjects

A T Chan

Publications and source records attributed to A T Chan.

At least 73 records · Page 4Linked to original sources
PubMed1996

Endoscopic cystgastrostomy: role of endoscopic ultrasonography.

We report a case of successful endoscopic cystgastrostomy guided by endoscopic ultrasound after an unsuccessful attempt of "blind" drainage. Endoscopic drainage of pseudocysts without endoscopic ultrasonography is an appropriate initial approach by experienced endoscopists in carefully selected patients. In cases in which an intraluminal impression by the pseudocyst is not well visualized, or the conventional approach has not established drainage, endoscopic ultrasound provides excellent localization for the therapeutic maneuver.

Drainage↗
PubMed1996

Thoracoscopic talc insufflation versus talc slurry for symptomatic malignant pleural effusion.

BACKGROUND: Talc has been generally accepted to be the most effective sclerosant for chemical pleurodesis, although the optimal route of administration remains unclear. METHODS: We designed a prospective, randomized study to compare video-assisted thoracoscopic talc insufflation with bedside talc slurry in the treatment of malignant pleural effusion. From September 1993 to November 1995, 57 patients were recruited and randomized to either video-assisted thoracoscopic talc insufflation under general anesthesia (n = 28) or talc slurry by the bedside (n = 29). Patients with poor general condition (Karnofsky score less than 30%), poor pulmonary function (forced expiratory volume in 1 second less than 0.5 L), or trapped lungs were excluded from this study. Five grams of purified talc was used for either video-assisted thoracoscopic talc insufflation or talc slurry. RESULTS: There was no statistically significant difference between the two groups of patients with respect to age, sex ratio, chest drainage duration, postprocedural hospital stay, parenteral narcotics requirement, complications, or procedure failure (ie, recurrence). CONCLUSIONS: Video-assisted thoracoscopic talc insufflation has not been shown to be a superior approach compared with talc slurry in our study. Because the former demands more resources, we advocate that talc slurry should be considered as the procedure of choice in the treatment of symptomatic malignant pleural effusion in patients who do not have trapped lungs.

Aged↗
PubMed1995

A prospective randomized study of chemotherapy adjunctive to definitive radiotherapy in advanced nasopharyngeal carcinoma.

PURPOSE: A prospective randomized trial was conducted to compare chemoradiotherapy against radiotherapy alone in the treatment of locoregionally advanced nasopharyngeal carcinoma. METHODS AND MATERIALS: Eighty-two patients with histologically proven nasopharyngeal carcinoma who had either Ho's N3 staging or any N stage with a nodal diameter of > or = 4 cm were entered. Seventy-seven patients were evaluated for tumor response and survival. The patients were randomized to receive two cycles of cisplatin 100 mg/m2 Day 1,5-fluorouracil 1000 mg/m2 24-h infusion Days 2, 3, and 4 before radical radiotherapy, and four cycles of postradiotherapy chemotherapy (37 patients) or radiotherapy alone (40 patients). All patients received radical radiotherapy to the nasopharynx and neck. The nasopharynx and upper neck were treated to 66 Gy by conventional fractionation and the lower neck to 58 Gy. Booster radiotherapy (7.5 Gy/two fractions/week) was given to any residual nodes after standard radiotherapy. RESULTS: The patient characteristics, including staging, were similar in both arms. The overall response rate to neoadjuvant chemotherapy was 81% (19% complete response, 62% partial response). The rates of radiotherapy for boosting parapharyngeal disease or residual lymph nodes were not significantly different in the two arms. The overall complete response rate to chemoradiotherapy was 100%, and to radiotherapy alone, 95%. Toxicities in the chemoradiotherapy arm were mainly myelosuppression, nephrotoxicity, and nausea and vomiting. The degree of mucositis was not significantly different in the two arms. There was no treatment-related death. The median follow up was 28.5 months. The 2-year overall survival was 80% in the chemoradiotherapy arm and 80.5% in the radiotherapy arm. The 2-year disease-free survival was 68% in the chemoradiotherapy arm and 72% in the radiotherapy arm, without significant difference between the two arms. The locoregional relapse rate, distant metastatic rate, and median time to relapse were also not significantly different between the two arms. CONCLUSION: Despite promising tumor response rates from Phase II trials, this prospective randomized trial has demonstrated no benefit from adjunctive chemotherapy to radiotherapy in the treatment of locoregionally advanced nasopharyngeal carcinoma.

Adult↗
PubMed1995

A retrospective study of the use of cisplatinum-5-fluorouracil neoadjuvant chemotherapy in cervical-node-positive nasopharyngeal carcinoma (NPC).

A retrospective study on 422 nasopharyngeal carcinoma (NPC) patients with cervical nodal metastases treated between 1984 and 1987 was performed. 169 received neoadjuvant chemotherapy (CHEMO) with cisplatinum and 5-fluorouracil for two or three courses prior to definitive radiotherapy and 253 were treated by radical radiotherapy alone (NCHEMO). While the primary tumour (T-stage) prognosticators had been comparable between the two groups, CHEMO had significantly more advanced cervical nodal metastases with bulkier nodes and more low-cervical and supraclavicular nodes (P < 0.05) which could account for its overall worse survival, poorer regional tumour control and a trend towards worse systemic tumour control. The worse regional control in CHEMO for Ho's N1 could be the result of more bulky nodes and more tumours infiltrating the skull base and/or causing cranial nerve(s) palsy. There was no statistical or apparent difference between CHEMO and NCHEMO for the same Ho's overall stages of NPC with comparable nodal and primary tumour characteristics for the clinical endpoints of actuarial survival rate (ASR), disease-free survival rate (DFS), free of local failure survival rate (FLF), and free from distant metastases survival rate (FDM), despite the presence of significantly more fixed nodes and bulky nodes. This suggests a possible beneficial effect of the neoadjuvant chemotherapy. However, multivariate analysis has not shown the administration of the neoadjuvant chemotherapy to be of prognostic significance. Even though the chemotherapy was well tolerated with little toxicity, we recommend against the routine use of neoadjuvant chemotherapy in cervical-node-positive NPC outside the context of a prospective randomised clinical trial.

Adolescent↗
PubMed1995

Acute monoblastic leukaemia with conjunctival tumours.

We describe an unusual occurrence of bilateral conjunctival tumours in a 25-year-old woman. This was the first sign of relapse of acute monoblastic leukaemia. There was also both marrow relapse and subsequent skin infiltration. No central nervous system involvement was detected. The tumours appeared as pink raised lesions in the upper conjunctivae of both eyes. They were not associated with pain or visual impairment. Conjunctival tumour biopsy revealed a dense mononuclear cell infiltration. Complete remission (conjunctival tumours, skin infiltration and bone marrow) was attained following systemic chemotherapy in combination with intrathecal chemotherapy.

Adult↗
PubMed1995

A rare site and appearance for lymphomatous recurrence.

A patient with a recurrence of large cell lymphoma is reported. There was psoas muscle involvement, which showed ring enhancement post-intravenous contrast on CT scan. Ring enhancement in skeletal muscle infiltration by lymphoma has not been described previously.

Adult↗
PubMed1995

Video-assisted thoracoscopic wedge resections of pulmonary metastatic osteosarcoma: should it be performed?

We studied the use of video-assisted thoracoscopic (VAT) surgery in the management of metastatic osteosarcoma. From September 1993 to March 1994, we performed a total of 11 VAT wedge resections of pulmonary metastatic osteosarcoma in seven patients (six males, one female, age 12 to 46 years). Three patients had bilateral procedures performed either under the same anaesthesia or in stages. One patient had two operations on the same side. The average number of nodules excised was three. Two patients subsequently required formal lobectomies when the metastatic tumours were either too big or too close to the hilum for safe wedge resections. There was one death on postoperative day 3 due to dysrhythmia. One patient died 5 months later from a progression of his underlying disease. Two patients remained disease free up to 8 and 12 months, respectively, from their first operations. The average postoperative chest drain duration was 1.4 +/- 0.7 days and hospital stay 2.3 +/- 1.1 days. The procedure was well tolerated and postoperative morbidity was minimal. We conclude that although VAT wedge resection of pulmonary metastatic osteosarcoma is feasible technically and is associated with a short hospital stay and minimal morbidity, this approach cannot be recommended when complete resection of all metastases is the goal as the technique relies heavily on computed tomographic scans to detect nodules. Recurrence of metastasis from 4 to 6 months in three of seven patients argues against VAT surgery being an adequate procedure. The high cost of the staplers, in addition, is a secondary consideration.

Adolescent↗
PubMed1994

IL-2-dependent NK cell responses discovered in virus-infected beta 2-microglobulin-deficient mice.

In vivo NK cell responses to lymphocytic choriomeningitis virus were studied in CD8+ T cell-deficient mice. On day 7 after infection, dramatically elevated splenic NK cell activities were observed in both beta 2-microglobulin-negative (beta 2-m-/-) mice deficient in CD8+ T cells and anti-CD8-treated C57BL/6 animals. The enhanced responses could be attributed to increased numbers of activated NK1.1+CD3- cells. The day 7 NK cell responses in beta 2-m-/- mice, but not in normal C57BL/6 animals, were cyclosporin A sensitive and coincided with IL-2 production and high affinity IL-2R expression on NK cells. Proof that IL-2 played an essential role in day 7 responses was provided by the observation that IL-2-/- x beta 2-m-/- mice lacked the late NK cell activation. Taken together, these results showed that NK cells can be activated and expanded by an IL-2-dependent pathway. Because these responses can only be measured in the absence of CD8+ T lymphocytes, an exciting model of networking between T and NK cells in response to viruses is postulated.

Animals↗
PubMed1994

Cerebrovascular event following taxol infusion.

We report a patient with advanced carcinoma of the ovary treated with salvage taxol infusion who experienced a cerebrovascular event 36 hours afterwards. No similar case has been reported to date.

Adenocarcinoma, Mucinous↗
PubMed1993

Cholinergic regulation of phase II interdigestive pancreatic secretion in humans.

Small fluctuations in cholinergic input may be involved in the regulation of human interdigestive pancreatic secretion. To determine the effects of small changes in cholinergic tone on phase II interdigestive trypsin secretion, we gave cholinergic agonists or antagonists to 17 healthy fasting subjects who underwent gastrointestinal intubation. Duodenal trypsin outputs, gastroduodenal motility, and plasma levels of pancreatic polypeptide (PP) as a marker of cholinergic tone were measured during intravenous infusion of bethanechol (0, 5, or 40 micrograms.kg-1.h-1) or atropine (0, 4, or 16 micrograms.kg-1.h-1) given during phase II alone or in combination based on a 3 x 3 factorial design. Data were evaluated by a response surface analysis of the average log values for the test period (using the average of log values of the control period as a covariate). Bethanechol increased trypsin output (p < 0.05) and plasma concentrations of PP (p < 0.05) within the ranges of spontaneous fluctuations of trypsin output and PP during phase II, but did not disrupt the periodicity of pancreatic secretion or the characteristic cyclical pattern of interdigestive motility and induction of phase III activity. Atropine markedly decreased trypsin output (p < 0.05) and plasma concentrations of PP (p < 0.05) and abolished the cycling of interdigestive pancreatic secretion and motor activity. These data suggest the hypothesis that cholinergic pathways participate in the control of interdigestive pancreatic secretion during phase II, while enzyme secretion during phase III may be regulated by other mechanisms.

Acetylcholine↗
PubMed1992

Adrenergic modulation of interdigestive pancreatic secretion in humans.

Whether the adrenergic pathways participate in the control of interdigestive pancreatic function in humans is uncertain. To determine if changes in alpha- or beta-adrenergic tone modulate interdigestive pancreatic enzyme output, 16 healthy subjects were intubated with an orojejunal tube to collect and quantify pancreatic trypsin secretion and record motility. After observation of a complete interdigestive cycle (control period), eight groups of two subjects each received 2-hour intravenous infusions of the alpha- and beta-agonist epinephrine (50 ng.kg-1.min-1), the alpha-antagonist phentolamine (5 mg/2 min followed by 500 micrograms/min), the beta-antagonist propranolol (5 mg/2 min followed by 80 micrograms/min), or saline as control, alone or in combination. Drugs were assigned in a random mode according to a 2(3) factorial design. Analysis of variance showed that epinephrine decreased trypsin output by 43% (P less than 0.05). By contrast, trypsin output was increased fourfold in the presence of phentolamine (P less than 0.01), whereas propranolol had no effect. These data suggest that an inhibitory alpha-adrenergic tone modulates human interdigestive pancreatic enzyme secretion whereas beta inputs are less important.

Adrenergic Fibers↗
PubMed1988

Human pancreatic secretion during phase II antral motility of the interdigestive cycle.

We determined if changes in the irregular motor activity of phase II, the dominant motility phase in awake fasting humans, are associated with fluctuations in pancreatic secretion by intubating the upper gastrointestinal tract of 15 healthy humans and recording antral and duodenal motility and obtaining duodenal samples for one or two interdigestive motility cycles. Antral phase II activity was graded as having low, intermediate, or high frequency of contractions and related to duodenal trypsin output and plasma concentrations of motilin and human pancreatic polypeptide (HPP), a marker of vagal cholinergic tone. Low, intermediate, and high phase II motor activities were significantly associated with trypsin outputs (U/10 min; mean +/- SE) of 576 +/- 137, 1,441 +/- 225, and 3,621 +/- 521, respectively (P less than 0.001). Plasma motilin levels did not vary with the grades of phase II motility (P greater than 0.1), but levels of plasma HPP and the grades of phase II motility were positively correlated (P less than 0.001). The close correlation among motility, pancreatic secretion, and plasma HPP during phase II suggests that vagal cholinergic pathways are involved in the common regulatory mechanism controlling phase II interdigestive motility and pancreatic secretion.

Adolescent↗
PubMed1986

Estimated versus measured basal energy requirements in patients with Crohn's disease.

Increased energy expenditure associated with active inflammation has been thought to be one cause of weight loss in patients with Crohn's disease. Our aim was to test this hypothesis by determining if resting energy expenditure (REE) measured by indirect calorimetry was greater than the predicted energy expenditure (PEE) calculated from the Harris-Benedict formula (variables--sex, age, height, and weight) in each patient. Fifty-four patients with radiographic evidence of Crohn's disease were studied. There was a highly significant relationship (p less than 0.001) between REE and PEE, which can be expressed as follows: REE = 39.40 + 0.99 (PEE). The mean REE was 1427 +/- 228 kcal/day, whereas the mean PEE was 1404 +/- 197 kcal/day. Patients with the lowest weights when expressed as percentages of ideal body weights had the greatest resting energy expenditure per kilogram of body weight (r = -0.73, p less than 0.001). The mean REE per kilogram per day was 25 +/- 4 kcal, and only 4 of 54 patients (7%) had REE greater than or equal to 30 kcal/kg X day. Thus, REE measured by indirect calorimetry in Crohn's disease patients was not significantly higher than PEE that can be estimated from the Harris-Benedict equation. These findings show that most Crohn's disease patients without fever or sepsis do not have increased REE.

Adult↗
PubMedDate not supplied

Pathogenesis of steatorrhea in primary biliary cirrhosis.

To investigate the pathophysiology of steatorrhea in primary biliary cirrhosis, the severity of steatorrhea, small bowel histology and function, cholestasis, exocrine pancreatic secretion and liver histology were studied. Twenty-four primary biliary cirrhotic patients had a quantitative stool fat collection, serum bilirubin and alkaline phosphatase and liver biopsies. From this group, ten had further studies: a small bowel biopsy (n = 7); a D-xylose test (n = 9); measurement of pancreatiobiliary concentrations and outputs after intravenous cholecystokinin (n = 10); essential amino acid perfusion of the duodenum (n = 9), and eating a test meal (n = 7). D-xylose absorption was normal, and only one patient had a minimal small bowel mucosal abnormality. Pancreatic lipase outputs in response to cholecystokinin were low in two primary biliary cirrhotic patients, but were greater than 10% of normal. Postprandial lipase outputs were normal except in one patient who had abnormal duodenal acidification. Mean enzyme outputs in primary biliary cirrhotic patients were normal in response to essential amino acid perfusion; but 6 had low lipase and 5 had low trypsin outputs which were associated with decreased bile acid outputs (p less than 0.03). Severity of steatorrhea was associated with reduced bile acid outputs and concentrations (r = 0.82; p less than 0.0001), degree of cholestasis (serum bilirubin; r = 0.88; p less than 0.001) and advanced histologic stages (p less than 0.005). Severe intraluminal bile acid deficiency combined with a submaximal intraluminal stimulus (essential amino acids) may be associated with decreased exocrine pancreatic secretion in primary biliary cirrhosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMedDate not supplied

Post-endarterectomy carotid ultrasonic duplex scanning concordance with contrast angiography.

The results of ultrasonic duplex scanning combined with spectral analysis are compared with the results of contrast angiography in patients after endarterectomy in which recurrence of carotid arterial disease was suspected. Thirty-six patients underwent a duplex scan study within 3 months of their post-operative angiogram, performed at their physician's discretion (44 studies). The overall accuracy of the method was 80%. Our ability to predict a greater than 50% diameter reduction along with total occlusion was 94%. The measure of agreement corrected for chance between arteriography and duplex scanning as expressed by the Kappa statistic was 0.675 +/- SE (K) 0.096. This level of agreement compared favorably to that of inter- and intra-observer variability in reading cerebral angiograms. The accuracy reported justifies the clinical use of ultrasonic duplex scanning in the detection of recurrent stenosis after carotid endarterectomy.

Blood Flow Velocity↗