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Biomedical subjects

K T Chan

Publications and source records attributed to K T Chan.

At least 19 recordsLinked to original sources
PubMed2004

Treatment of long, diffuse in-stent restenosis with sirolimus-eluting stents.

Treatment of long, diffuse in-stent restenosis remains a therapeutic challenge. We report the successful use of multiple sirolimus-eluting stents (three 33-mm long stents) in a long, diffuse in-stent restenotic lesion. No major adverse cardiovascular events, including acute/subacute/delayed stent thrombosis, were noted at ten months. Angiography at six months showed widely patent stents with 19% restenosis only at the worst segment.

Aged↗
PubMed2003

The use of a distal occlusion balloon protection device in acute coronary syndrome.

We report our early experience in using the PercuSurge GuardWire Plus system as a distal protection device in patients with acute coronary syndrome and acute myocardial infarction. Forty-three patients received percutaneous coronary intervention with the GuardWire Plus system. Thirteen had unstable angina, five had non-Q myocardial infarction and 25 had ST segment elevation myocardial infarction. Forty-one target lesions were in native coronary vessels and two were in saphenous vein grafts. Total occlusion occurred in 18 patients. The mean occlusion time by the distal protective balloon was 262.8 +/- 114.1 s. Preoperatively, TIMI 0 flow was present in 18, TIMI II flow in two and TIMI III flow in 23 patients. Post-operatively, TIMI II and TIMI III flow were established in two and 41 patients, respectively. All procedures were successful and the GuardWire Plus system was successfully deployed in all but two patients. There was no procedure-related major adverse clinical event. There was no major adverse clinical event at 30 days. There was no device-related complication. We believe that the GuardWire Plus system is safe and feasible in patients with acute coronary syndrome and acute myocardial infarction.

Angina, Unstable↗
PubMed2001

A humanized monoclonal antibody constructed from intronless expression vectors targets human hepatocellular carcinoma cells.

An anti-human hepatocellular carcinoma (HCC) monoclonal antibody, hHP-1, was genetically humanized from a murine monoclonal antibody. In this study, a concept of positional template approach was applied to design the amino acid sequence of hHP-1's variable region, and synthetic DNA fragments for protein expression were produced through overlapping PCR from single strand oligonucleotides. Synthetic DNA fragments and human antibody constant region cDNA were used to construct two CMV promotor-based expression vectors for the antibody light and heavy chains, in which the variable region was connected directly to the constant region without an intron sequence. Completely assembled humanized antibody was successfully expressed in mammalian cells as IgG1 kappa molecules and purified using protein A affinity column. The immunogenicity of the hHP1 was estimated by the amino acid sequence and determined through a HAMA (human anti-murine antibody) serum reaction assay. Results indicated that the immunogenicity of hHP-1 was significantly reduced. In vitro binding activity assay showed that the hHP-1 had retained its binding function to a human HCC SMMC-7721 cell-line, without cross binding to other human normal tissues. Immunofluorescence staining showed that hHP-1 had a strong binding activity to SMMC cells. A competitive binding assay showed that the relative binding activity of hHP-1 was approximately 25% binding activity of the original murine antibody. Our results indicate that a humanized antibody could be produced using intronless vectors and expressed as a complete IgG1 kappa antibody. Hence we believe that hHP-1 could be a potential candidate for HCC treatment.

Amino Acid Sequence↗
PubMed2001

Lumbosacral plexopathy in gunshot wounds and motor vehicle accidents: comparison of electrophysiologic findings.

OBJECTIVE: To characterize the differences between injuries to the lumbosacral (LS) plexus caused by gunshot wounds (GSW) and motor vehicle crashes (MVC) with regard to the location and extent of involvement. DESIGN: A retrospective review of electrophysiologic data from an electromyography laboratory of a county hospital. Nineteen patients with GSW and ten patients with MVC diagnosed by electromyography with an LS plexopathy were included in the study. Injuries were categorized by the number of anatomic quadrants of the LS plexus: upper anterior, upper posterior, lower anterior, and lower posterior. Comparison of upper vs. lower portions and bilaterality of LS plexus involvement was also made. Statistical analyses were performed with two-tailed Fisher's exact and general association tests. RESULTS: Lower portions of the plexus were involved more frequently in patients with MVC compared those observed in patients with GSW. Upper portions of the LS plexus were more involved compared with the lower portions in patients with GSW injuries. More sections of the plexus were involved in patients with MVC compared with those in patients with GSW. CONCLUSIONS: Compared with patients with MVC, patients with GSW had a greater chance of involvement of the upper portion of the plexus. The reverse was true for the lower portion. Hopefully this information will aid the electromyographer and rehabilitation team in the diagnosis and treatment of traumatic plexopathies caused by different etiologies.

Accidents, Traffic↗
PubMed2001

Differential expression of a stress-modulating gene, BRE, in the adrenal gland, in adrenal neoplasia, and in abnormal adrenal tissues.

Genes that modulate the action of hormones and cytokines play a critical role in stress response, survival, and in growth and differentiation of cells. Many of these biological response modifiers are responsible for various pathological conditions, including inflammation, infection, cachexia, aging, genetic disorders, and cancer. We have previously identified a new gene, BRE, that is responsive to DNA damage and retinoic acid. Using multiple-tissue dot-blotting and Northern blotting, BRE was recently found to be strongly expressed in adrenal cortex and medulla, in testis, and in pancreas, whereas low expression was found in the thyroid, thymus, small intestine and stomach. In situ hybridization and immunohistochemical staining indicated that BRE was strongly expressed in the zona glomerulosa of the adrenal cortex, which synthesizes and secretes the mineralocorticoid hormones. It is also highly expressed in the glial and neuronal cells of the brain and in the round spermatids, Sertoli cells, and Leydig cells of the testis, all of which are associated with steroid hormones and/or TNF synthesis. However, BRE expression was downregulated in human adrenal adenoma and pheochromocytoma, whereas its expression was enhanced in abnormal adrenal tissues of rats chronically treated with nitrate or nitrite. These data, taken together, indicate that the expression of BRE is apparently associated with steroids and/or TNF production and the regulation of endocrine functions. BRE may play an important role in the endocrine and immune system, such as the cytokine-endocrine interaction of the adrenal gland.

Adrenal Gland Neoplasms↗
PubMed2000

Sacroiliac joint pain referral zones.

OBJECTIVE: To determine the patterns of pain referral from the sacroiliac joint. STUDY DESIGN: Retrospective. PARTICIPANTS/METHODS: Fifty consecutive patients who satisfied clinical criteria and demonstrated a positive diagnostic response to a fluoroscopically guided sacroiliac joint injection were included. Each patient's preinjection pain description was used to determine areas of pain referral, and 18 potential pain-referral zones were established. OUTCOME MEASURES: Observed areas of pain referral. RESULTS: Eighteen men (36.0%) and 32 women (64.0%) were included with a mean age of 42.5 years (range, 20 to 75 yrs) and a mean symptom duration of 18.2 months (range, 1 to 72 mo). Forty-seven patients (94.0%) described buttock pain, and 36 patients (72.0%) described lower lumbar pain. Groin pain was described in 7 patients (14.0%). Twenty-five patients (50.0%) described associated lower-extremity pain. Fourteen patients (28.0%) described leg pain distal to the knee, and 6 patients (14.0%) reported foot pain. Eighteen patterns of pain referral were observed. A statistically significant relationship was identified between pain location and age, with younger patients more likely to describe pain distal to the knee. CONCLUSIONS: Pain referral from the sacroiliac joint does not appear to be limited to the lumbar region and buttock. The variable patterns of pain referral observed may arise for several reasons, including the joint's complex innervation, sclerotomal pain referral, irritation of adjacent structures, and varying locations of injury with the sacroiliac joint.

Adult↗
PubMed1999

Modulation of Ca2+-dependent anion secretion by protein kinase C in normal and cystic fibrosis pancreatic duct cells.

The study investigated the role of protein kinase C (PKC) in the modulation of agonist-induced Ca2+-dependent anion secretion by pancreatic duct cells. The short-circuit current (ISC) technique was used to examine the effect of PKC activation and inhibition on subsequent ATP, angiotensin II and ionomycin-activated anion secretion by normal (CAPAN-1) and cystic fibrosis (CFPAC-1) pancreatic duct cells. The ISC responses induced by the Ca2+-mobilizing agents, which had been previously shown to be attributed to anion secretion, were enhanced in both CAPAN-1 and CFPAC-1 cells by PKC inhibitors, staurosporine, calphostin C or chelerythrine. On the contrary, a PKC activator, phorbol 12-myristate 13-acetate (PMA), was found to suppress the agonist-induced ISC in CFPAC-1 cells and the ionomycin-induced ISC in CAPAN-1 cells. An inactive form of PMA, 4alphad-phorbol 12, 13-didecanote (4alphaD), was found to exert insignificant effect on the agonist-induced ISC, indicating a specific effect of PMA. Our data suggest a role of PKC in modulating agonist-induced Ca2+-dependent anion secretion by pancreatic duct cells. Therapeutic strategy to augment Ca2+-activated anion secretion by cystic fibrosis pancreatic duct cells may be achieved by inhibition or down-regulation of PKC.

Adenosine Triphosphate↗
PubMed1999

Telomerase activity in thyroid malignancy.

Telomerase activity seems to play a role in the development and pathogenesis of thyroid carcinoma. Its incidence of expression and its application as a tumor marker remain to be elucidated. Thyroid tissues obtained during thyroidectomy from 1996-1998 were rapidly frozen and stored at -80 degrees C until processed. Telomerase activity was determined using telomeric repeat amplification protocol (TRAP). Histology of the tissue examined (67 benign and 59 malignant) was reviewed. Telomerase activity was detected in 15 of 52 papillary carcinomas (29%); 1 of 1 thyroid lymphoma (100%); 1 of 2 anaplastic carcinomas (50%); and 2 of 16 lymphocytic thyroiditis specimens (13%). Telomerase activity was not detectable in 35 normal thyroid, 9 follicular adenoma, 7 nodular hyperplasia, 2 follicular carcinoma, and 2 medullary carcinoma. Lymphocytic thyroiditis was detected in 8 of 37 (22%) apparently normal thyroid tissues adjacent to papillary thyroid carcinoma and telomerase activity was present in 2 of these 8 specimens (25%). In conclusion, telomerase does not appear to be frequently activated in papillary thyroid carcinoma. The association of lymphocytic thyroiditis with papillary thyroid carcinoma may limit its clinical usefulness as a tumor marker.

Adolescent↗
PubMed1991

Sclerosing peritonitis complicating prolonged use of chlorhexidine in alcohol in the connection procedure for continuous ambulatory peritoneal dialysis.

Sclerosing peritonitis (SP) is an uncommon but serious complication of CAPD with various suggested etiologies. We have documented 14 cases of SP in 18 patients who had used chlorhexidine in alcohol (ChA) in the connection procedure for CAPD. Thirteen died. Nine of the 14 patients had been transferred to hemodialysis or renal transplantation, yet all still developed symptoms of SP within a few months after transfer - even the 5 who were originally asymptomatic. The main symptoms of SP were peritoneal ultrafiltration failure, exudative bloody ascites and intestinal obstruction. They presented at around 5 years (30-80 months) after commencement of CAPD. Most deaths were related to intestinal obstruction. Four other patients with a comparable duration of ChA exposure were continued on CAPD with the Travenol Spike System (TSS), without further exposure to ChA. They were all asymptomatic of SP after 9-12 months. Comparing the 2 groups of asymptomatic patients, those transferred to TSS had a much better outcome after 9 months than those transferred to HD or renal transplantation (P = 0.0476). We suggest that ChA is the main cause of SP in our patients and that continuing CAPD without further exposure to ChA is a better alternative than stopping CAPD to prevent the progression of SP.

Adult↗
PubMed1990

Sclerosing peritonitis complicating continuous ambulatory peritoneal dialysis with the use of chlorhexidine in alcohol.

Sclerosing peritonitis (SP) is an uncommon but serious complication of CAPD with various suggested etiology. We have documented 14 cases of SP in 18 CAPD patients using chlorhexidine in alcohol (ChA) in the connection procedure; 13 died. Nine of the 14 patients had been transferred to haemodialysis or renal transplantation, yet all still developed symptoms of SP within a few months after transfer even though 5 of them were originally asymptomatic. The main symptoms of SP were peritoneal ultrafiltration failure, exudative bloody ascites and intestinal obstruction. They present at around 5 years (30-80 months) after commencement of CAPD. Four other patients with a comparable duration of ChA exposure were continued on CAPD with a Travenol Spike System (TSS) without further exposure to ChA. They were all asymptomatic of SP after 9-12 months. Comparing the 2 groups of asymptomatic patients at 9 months after transfer, those transferred to TSS have a much better outcome than those transferred to HD or renal transplantation (P = 0.0476). We concluded that ChA is the main cause of SP in our patients and continuing CAPD without further exposure to ChA is a better alternative than stopping CAPD in preventing the progression of SP.

Adult↗
PubMed1986

Giant cell tumor of the distal end of the radius treated by the resection and free vascularized iliac crest graft.

Juxtaarticular giant cell tumor involving the distal radius presents a special problem of reconstruction after tumor excision. A tailored block of vascularized iliac crest graft with its feeding artery (i.e., the deep circumflex iliac artery) joined to the ulnar artery was used as a replacement for the resected distal radius, thereby creating a new wrist joint. Excellent graft survivals were observed in all four cases. The wrists, when assessed 24-48 months after surgery, were found to have good ranges of movement, although with mild dorsal subluxation. These results compared well with other means of wrist reconstruction (i.e., the vascularized fibular graft). Although conventional means of arthrodesis give acceptable hand function, the absence of wrist motion is unacceptable to the young and active, who may prefer the method described in this article.

Adult↗
PubMed1982

Species differences in the urinary excretion of the novel primary amine conjugate: tocainide carbamoyl O-beta-D-glucuronide.

The metabolism of the antiarrhythmic drug tocainide (I) has been shown previously to occur via a novel pathway involving the addition of carbon dioxide to the primary amine nitrogen of I followed by conjugation with glucuronic acid. The product of this reaction, tocainide carbamoyl O-beta-D-glucuronide (II), the principal metabolite of I in humans, has been found to cyclize under strongly basic conditions to form 3-(2,6-xylyl)-5-methylhydantoin (III). Thus, evidence for the existence of II can be obtained by two different procedures: conversion of II to III in the presence of strong base and by hydrolysis of II with beta-glucuronidase. The principal purpose of the present investigation was to identify suitable species for studies of the mechanism involved in the formation of II, as well as to find an animal model suitable for toxicological evaluation of tocainide and structurally related compounds. Eight animal species were examined to identify those capable of metabolizing I into II. The fraction of an intraperitoneal dose excreted in urine as II was estimated by measurement of tocainide released by beta-glucuronidase mediated hydrolysis of urine and by the quantitation of III formed after alkalinization of urine samples. Urinary recovery of unchanged drug ranged from 9.5% of the dose in the gerbil to 48.7% in the cat. The percent of the dose excreted in urine as acid hydrolyzable conjugates ranged from less than 1% in the gerbil to a mean of 13% in the rabbit. Guinea pigs, dogs, cats, rabbits, and pigtail monkeys excreted amounts of II ranging from 0.2 to 2.4% of the dose. Thus, none of the species appeared to be a suitable model for the study of the mechanism of formation of II because of the quantitative insignificance of this pathway.

Animals↗
PubMed1982

Finger tip injuries--a prospective study on seven methods of treatment on 200 cases.

7 common methods of treatment were selected at random for 200 cases of finger tip injuries. The methods included split skin grafting, full-thickness skin grafting, volar V-Y advancement, Kutler's bilateral V-Y advancement, revision amputation, cross-finger flap and simple dressing. These cases were seen weekly until healing was completed and then at 3 and 6 months. A proper functional assessment was given to each case at the last visit. The results were analysed along the parameters of wound healing, appearance, scar condition, sensory return, finger joint movements, motor-power and sick-leave benefits. The best results were obtained from the volar V-Y advancement method. Results were most unfavourable when cross-finger flaps were used. This latter method, therefore, was condemned. Simple dressing gave excellent results if one disregarded the lengthy period of wound healing, a somewhat tender scar and possible beaking of the nails. The other methods gave satisfactory results but had no outstanding advantage.

Amputation, Traumatic↗
PubMed1982

Complications in treatment of trochanteric fractures using Ender's nails--a review of 120 patients.

A prospective study of 120 Chinese patients with trochanteric fractures treated with the surgical method of Ender's Nailing was undertaken. The average age of the patients was 79 years (ranged from 57 to 105 years). The follow-up period ranged from 4 to 18 months, with an average of 8 1/2 months. The mortality rate was 6%. There was no incidence of non-union, delayed union or deep wound infection. Local complications included extrusion of the nails, perforation of the femoral head, supracondylar fracture of the femur, mild limb shortening and external rotational deformity. Hip and knee pain occurred in a small percentage of patients but these tended to improve with time. Weight bearing walking could be started in the first week after operation in most of the patients. The functional result at 6 months was good in 73% of the patients. This method had the advantage of a limited surgical approach, minimal blood loss and good functional result. Analysis of the causes of the local complications indicated that if operative precautions were taken, morbidity could be reduced.

Aged↗
PubMed1981

[Effect of strophanthin and celanide on the dynamics of development of postischemic cerebrovascular phenomena].

In acute experiments on anesthetized cats with artificial respiration and isolated autohemoperfusion of the cerebral vessels by the pump of stabilized capacity (heparin was injected intravenously), cerebral ischemia was evoked by the stopping of the perfusion pump for 15 minutes. In the postischemic period (after perfusion resumption), 2 phases of the perfusion pressure (PP) changes were noted: at the beginning the PP lowering followed by the long-term increase (above the basic level). It is assumed that the PP changes reflect the time course of the development of suggestive postischemic cerebrovascular phenomena: hyper- and hypoperfusion. Preliminary intravenous injection (40-90 min before ischemia) of strophanthine and celanide (0.05 and 0.1 mg/kg) enhanced and extended the first phase and hampered the development of the second phase PP changes. Administration of strophanthine 90-120 min after ischemia (during the PP increase phase) did not alter the cerebrovascular resistance to the blood flow. Under these conditions the response of the cerebral vessels to strophanthine decreased as compared to that in intact (non-ischemized) cats.

Animals↗
PubMedDate not supplied

[The clinical efficacy of and tolerance for lariam (mefloquine) in tropical malaria in the south of the Socialist Republic of Vietnam].

The study was performed in the area of distribution of tropical malaria resistant to 4-aminoquinolines (Vietnam) on 30 patients receiving lariam (mefloquine). The results were compared to the standard therapy with quinine and fansidar. They indicate a high efficacy of and a good tolerance to the drug tested. The use of lariam leads to a more rapid (as compared to the standard treatment) elimination of parasitemia and complete eradication of the disease relapses. The findings make it possible to recommend lariam for the prevention and treatment of tropical malaria.

Adolescent↗