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Ma Q, Chan P, Yang J. [Association between DLST gene polymorphism and Alzheimer's disease]. ZHONGHUA YI XUE ZA ZHI 2001; 81:1246-8. [PMID: 11825528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To investigate the association between the polymorphic alleles of dihydrolipoamide succinyltransferase (DLST) gene cDNA at position A19117G in intron 13 and C19183T in exon 14 and the risk for sporandic Alzheimer's disease (SAD). METHODS The polymorphism of DLST gene was detected using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques in 105 patients with sporadic Alzheimer disease and 109 normal controls. RESULTS The frequency of AT/AC genotype was found to be significantly higher in SAD patients (21%) than in controls (10%) with an odds ratio of 2.36 (P < 0.05). The frequencies of AC/AC, AT/AT genotypes and AC allele were slightly decreased in cases with SAD as compared with controls. While the frequencies of the GC/GC genotype and GC allele were slightly higher in SAD patients than in controls. However, these differences were not statistically significant (P > 0.05). CONCLUSION The AT/AC genotype of DLST gene is associated with an increased risk for SAD.
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Figueroa KP, Chan P, Schöls L, Tanner C, Riess O, Perlman SL, Geschwind DH, Pulst SM. Association of moderate polyglutamine tract expansions in the slow calcium-activated potassium channel type 3 with ataxia. ARCHIVES OF NEUROLOGY 2001; 58:1649-53. [PMID: 11594924 DOI: 10.1001/archneur.58.10.1649] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND The small-conductance calcium-activated potassium channel gene (hSKCa3) contains 2 CAG repeats, 1 of which is highly polymorphic. Although this repeat is not pathologically expanded in patients with schizophrenia, some studies have suggested an allelic association with schizophrenia. CAG expansions in other genes such as the alpha1 subunit of a brain-specific P/Q-type calcium channel gene cause spinocerebellar ataxia type 6, whereas the length of the CAG repeat in the RAI1 gene modifies the age of onset of spinocerebellar ataxia type 2. OBJECTIVES To evaluate expansions in the hSKCa3 polyglutamine domain as causative for ataxia, and to study the association between the length of the polyglutamine repeat and the presence of ataxia. METHODS We analyzed this repeat in 122 patients with autosomal dominant cerebellar ataxia, or sporadic ataxia, and compared allele distribution with 750 alleles seen in 2 healthy control groups and 172 alleles in patients with Parkinson disease. RESULTS The distribution of alleles in ataxia patients and controls was significantly different by Wilcoxon rank test (P <.001). Twenty-two or more polyglutamine tracts were more common in ataxia patients compared with controls by chi2 analysis (P<.001). CONCLUSION Longer stretches of polyglutamines in a human potassium channel are not causative for ataxia, but they are associated with the presence of ataxia. There is no association with the presence of Parkinson disease.
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Furrer H, Chan P, Weber R, Egger M. Increased risk of wasting syndrome in HIV-infected travellers: prospective multicentre study. Trans R Soc Trop Med Hyg 2001; 95:484-6. [PMID: 11706654 DOI: 10.1016/s0035-9203(01)90011-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
HIV-infected patients from moderate regions who travel in tropical countries may experience clinical disease progression due to exposure to bacteria (including mycobacteria), fungi and parasites. In the Swiss HIV Cohort Study we examined the hypothesis that travelling increases the risk of tuberculosis, wasting syndrome, cryptosporidiosis, isosporiasis, cryptococcosis, coccidiomycosis, histoplasmosis and Salmonella septicaemia. A total of 4549 participants were included (in 1988-98) of whom 596 (13.1%) travelled at least once. During 16,800 person-years of follow-up 231 patients developed at least 1 of the diseases of interest. Wasting syndrome was the only diagnosis significantly associated with travelling (hazard ratio 2.16, 95% confidence interval 1.09 to 4.30). The risk of wasting syndrome ('slim disease') should be taken into account when counselling HIV-infected patients intending to travel in tropical regions.
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Patterson L, Avery N, Chan P, Parlow JL. The addition of fentanyl does not alter the extent of spread of intrathecal isobaric bupivacaine in clinical practice. Can J Anaesth 2001; 48:768-72. [PMID: 11546717 DOI: 10.1007/bf03016692] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Fentanyl is commonly added to intrathecal local anesthetic solutions. In vitro data has shown fentanyl to render isobaric local anesthetics hypobaric, and alter the spread in artificial cerebrospinal fluid. This study examined whether the addition of fentanyl to isobaric bupivacaine with morphine leads to a clinically important alteration in the extent of spread of anesthesia. METHODS Forty-four ASA I-III patients undergoing lower limb orthopedic procedures completed this double-blind, placebo-controlled trial. Patients were randomized into one of two groups, receiving intrathecal bupivacaine 15 mg and preservative-free morphine 200 microg without (Control group), or with the addition of fentanyl 0.02 mg (Fentanyl group). Patients were maintained at a slight head-up tilt. Variables studied over three hours included sensory level to cold and pinprick, motor blockade (Bromage scale), and circulatory data. RESULTS No differences existed between the Fentanyl and Control groups with respect to highest level of block for cold: T4 (T2-T5) vs T3.5 (T3-T8) respectively (median, 95% confidence interval) or pinprick: T4 (T3-T6) vs T4.5 (T3-T8). Similarly, there was no difference in the time taken to reach maximum block height to cold (20 +/- 9 vs 23 +/- 13 min, mean +/- SD) or pinprick (20 +/- 9 vs 24 +/- 13 min). CONCLUSION The addition of fentanyl 0.02 mg to 0.5% bupivacaine with morphine does not affect the maximal block height or time to maximal block in clinical practice.
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Farrer M, Chan P, Chen R, Tan L, Lincoln S, Hernandez D, Forno L, Gwinn-Hardy K, Petrucelli L, Hussey J, Singleton A, Tanner C, Hardy J, Langston JW. Lewy bodies and parkinsonism in families with parkin mutations. Ann Neurol 2001; 50:293-300. [PMID: 11558785 DOI: 10.1002/ana.1132] [Citation(s) in RCA: 344] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous work has established that compound mutations and homozygous loss of function of the parkin gene cause early-onset, autosomal recessive parkinsonism. Classically, this disease has been associated with loss of dopaminergic neurons in the substantia nigra pars compacta and locus ceruleus, without Lewy body pathology. We have sequenced the parkin gene of 38 patients with early-onset Parkinson's disease (<41 years). Two probands with mutations were followed up. Clinical evaluation of their families was performed, blinded to both genetic and pathological findings. Chromosome 6q25.2-27 haplotype analysis was carried out independently of the trait; parkin gene expression was examined at both the RNA and protein levels. Haplotype analysis of these families revealed a common chromosome 6, with a novel 40 bp exon 3 deletion that cosegregated with disease. In the proband of the smaller kindred, an exon 7 R275W substitution was identified in addition to the exon 3 deletion; RNA analysis demonstrated that the mutations were on alternate transcripts. However, Lewy body pathology typical of idiopathic Parkinson's disease was found at autopsy in the proband from the smaller kindred. These data suggest that compound heterozygous parkin mutations and loss of parkin protein may lead to early-onset parkinsonism with Lewy body pathology, while a hemizygous mutation may confer increased susceptibility to typical Parkinson's disease.
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Chan P, Ashcroft GP, Cranfield KA. Operating theatre exsanguinators pose a low risk for transmission of infection. Anaesthesia 2001; 56:810. [PMID: 11493259 DOI: 10.1046/j.1365-2044.2001.02181-19.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chen YJ, Tsai CF, Chiou CW, Chan P, Chen SA. Effect of nitric oxide on strophanthidin-induced ventricular tachycardia. Pharmacology 2001; 62:213-7. [PMID: 11359997 DOI: 10.1159/000056097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Nitric oxide (NO) has been demonstrated to have several effects on the heart. Through the stimulation of guanylate cyclase, NO increases cyclic GMP and decreases intracellular calcium. The purpose of this study was to evaluate the effects of NO on ventricular arrhythmia induced by strophanthidin in guinea pigs and dogs. In experiment 1, after strophanthidin-induced ventricular tachycardia, guinea pigs received different doses of L-arginine (0, 25, 50, 100, 200, and 400 mg/kg; n = 10 for each dose), 200 mg/kg L-arginine combined with 100 mg/kg N(G)-nitro-L-arginine methylester (L-NAME, n = 10), or 200 mg/kg D-arginine (n = 10). In experiment 2, after strophanthidin-induced ventricular tachycardia, dogs (n = 7) received 200 mg/kg L-arginine. By 12-lead ECG, monophasic action potentials in left and right ventricles were recorded throughout the study. In experiment 1, guinea pigs which received 200 mg/kg or 400 mg/kg L-arginine had greater incidences of ventricular tachycardia termination (60 and 80%, respectively) than those which received 0, 25, 50, and 100 mg/kg L-arginine (0, 0, 20, and 30%, respectively), those which received L-arginine with L-NAME (0%), and those which received D-arginine (0%). In experiment 2, 5 (71%) of the dogs had successful termination of ventricular tachycardia. These findings suggest that L-arginine was effective in treating strophanthidin-induced ventricular tachycardia in vivo and that the underlying mechanism is through a NO pathway.
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Chang JJ, Chen TH, Chan P, Chen YJ, Hsu FL, Lo MY, Lin JY. The in vitro inhibitory effect of tannin derivatives on 3-hydroxy-3-methylglutaryl-coenzyme a reductase on vero cells. Pharmacology 2001; 62:224-8. [PMID: 11359999 DOI: 10.1159/000056099] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Coronary heart disease is still the major cause of death in industrialized countries. Multiple primary or secondary interventional trials to lower serum cholesterol in humans have resulted in significant reduction of coronary events and death, one of the major reasons attributed to developing a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor such as pravastatin. Developing new inhibitors of cholesterol synthesis is still common in the pharmaceutical industry. Tannin comprises a large group of natural polyphenolic compounds possessing antioxidant effects. The methods for analysis of specific inhibitors of mevalonate biosynthesis have already been well established by using Vero cells, a cell line obtained from kidneys of African green monkeys. Tannin derivatives isolated from different traditional Chinese herbs were dissolved in DMSO and incubated with Vero cells with or without the addition of 1 mmol/l mevalonate or 5 mmol/l sodium acetate for 24 h in order to observe cell growth. Pravastatin, a specific HMG-CoA reductase inhibitor, was used as positive control which could inhibit Vero cells growth effectively and cell growth inhibition was reversible after adding 1 mmol/l mevalonate. More than 50 tannin derivatives were used for the study, but only two compounds - proanthrocyanidin A-2 (belonging to the flavan-3-ol group) and 1,2,3,6-tetra-O-galloyl-beta-D-glucose (belonging to the gallotannin group) - showed significant growth inhibition of Vero cells. This study showed that some isolated tannin derivatives from traditional herbs were effective HMG-CoA reductase inhibitors which might be developed into new hypocholesterolemic agents.
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Chen TH, Liu JC, Chang JJ, Tsai MF, Hsieh MH, Chan P. The in vitro inhibitory effect of flavonoid astilbin on 3-hydroxy-3-methylglutaryl coenzyme A reductase on Vero cells. ZHONGHUA YI XUE ZA ZHI = CHINESE MEDICAL JOURNAL; FREE CHINA ED 2001; 64:382-7. [PMID: 11584575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
BACKGROUND Epidemiological studies have shown that hypercholesterolemia is a major risk factor for coronary heart disease. In clinical trials of lipid lowering therapy, 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase inhibitor has been shown to decrease cardiac events and mortality. Flavonoids are polyphenolic natural antioxidants existing in vegetables, fruits and beverages such as tea and wine. Previous studies have shown that some antioxidants had hypocholesterolemic effect, and flavonoid intake was associated with the decrease of mortality from coronary artery disease. The aim of this study was to evaluate the inhibitory effect of flavonoids on HMG-CoA reductase. METHODS The methods for analysis of specific inhibitors of mevalonate biosynthesis have been well-established, using Vero cells, a cell line obtained from kidneys of African green monkeys. Flavonoids isolated from different traditional Chinese herbs were dissolved in DMSO and incubated with Vero cells with or without the addition of 1 mM mevalonate or 5 mM sodium acetate in order to observe cell growth for 24 h. RESULTS Concentrations of 1 mM mevalonate or 5 mM sodium acetate were added into culture medium in order to observe the effect on cell growth. Different concentrations of pravastatin to inhibit cell growth were used as a positive control. About 40 flavonoid compounds were used for study, only one compound, astilbin (belonging to the flavonol group), showed significant inhibition of Vero cell growth. CONCLUSIONS This study shows that one flavonoid compound, isolated from traditional medicinal herbs, may be an effective HMG-CoA reductase inhibitor which might be developed into a new hypocholesterolemic agent.
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Zheng YT, Chan WL, Chan P, Huang H, Tam SC. Enhancement of the anti-herpetic effect of trichosanthin by acyclovir and interferon. FEBS Lett 2001; 496:139-42. [PMID: 11356198 DOI: 10.1016/s0014-5793(01)02391-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Trichosanthin (TCS) is a type I ribosome-inactivating protein that has a wide range of pharmacological activities. The present study investigated the effectiveness of TCS on herpes simplex virus (HSV-1). The anti-viral activity and toxicity of TCS on Vero cells were measured. Results showed that the ED(50), TD(50) and the therapeutic indices were 38.5, 416.5 and 10.9 microg/ml, respectively. Anti-viral activity of TCS was substantially potentiated when it was used in conjunction with other anti-viral agents. The ED(50) of TCS was reduced 125-fold by acyclovir at a concentration of 0.001 microg/ml, which was practically devoid of significant anti-viral activity. Similarly, the ED(50) of TCS was reduced 100-fold by interferon-alpha2a at a concentration of 100 IU/ml. In conclusion, TCS is effective against HSV-1 and other anti-viral agents such as acyclovir or interferon can potentiate its action substantially.
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Lam TP, Irwin M, Chow LW, Chan P. The use of focus group interviews in Asian medical education evaluative research. MEDICAL EDUCATION 2001; 35:510-513. [PMID: 11328523 DOI: 10.1046/j.1365-2923.2001.00898.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
OBJECTIVE To evaluate the use of focus group interviews in Asian medical education evaluative research. METHODS Randomly selected medical students were invited to participate in 30 focus group interviews to provide in-depth data about the effect on their learning of the introduction of early clinical skills. Efforts were made to meet all the students to help them understand the objectives of the focus group. Confidentiality was emphasised and a non-faculty interviewer was recruited for the interviews. RESULTS The students considered the use of focus groups to be a more meaningful way of collecting students' opinions than other methods, for example structured questionnaire, because it allowed an interactive discussion. They also felt that having an independent non-faculty interview moderator had encouraged them to express their opinions more candidly during the interviews. CONCLUSION The use of focus group interviews among Asian medical students for evaluative research is practical and efficient.
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Cheng JT, Liu IM, Yen ST, Juang SW, Liu TP, Chan P. Stimulatory effect of D-ephedrine on beta3-adrenoceptors in adipose tissue of rats. Auton Neurosci 2001; 88:1-5. [PMID: 11474539 DOI: 10.1016/s1566-0702(01)00225-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effect of ephedrine on beta3-adrenoceptos (beta3-AR) was studied in the isolated adipose tissue of Wistar rat. Incubation with D-ephedrine (0.1-10 microM) induced a concentration-dependent decrease of uptake of [14C]-deoxy-D-glucose into white adipose tissues (WAT). The inhibitory effect of D-ephedrine was potentiated by BRL 37344, the agonist of beta3-AR and concentration-dependently inhibited by SR 59230A, the selective antagonist of beta3-AR. The action of D-ephedrine on beta3-AR was further blocked by the antibodies for beta3-AR, but not the immunoglobulin. in a concentration-dependent manner. Moreover, D-ephedrine increased glycerol release from the isolated brown adipose tissues (BAT) and this action was also abolished by SR 59230A at concentration sufficient to block beta3-AR. Thus, these results suggest that D-ephedrine has the ability to activate beta3-AR both in WAT and BAT of Wistar rats in vitro.
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Chan P, Clarke P, Daniel FJ, Knight SR, Seevanayagam S. Efficacy study of video-assisted thoracoscopic surgery pleurodesis for spontaneous pneumothorax. Ann Thorac Surg 2001; 71:452-4. [PMID: 11235687 DOI: 10.1016/s0003-4975(00)02446-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND This study aims to assess the efficacy of video-assisted thoracoscopic surgery pleurodesis in the treatment of spontaneous pneumothorax with particular reference to the rate of recurrence after abrasion pleurodesis and postoperative neuralgia. METHODS One hundred one patients who underwent 109 video-assisted thoracoscopic surgery pleurodesis procedures in the Austin & Repatriation Medical Centre between January 1992 and June 1998 were identified from a computerized database. The follow-up period was from 8 months to 7 years and 1 month (mean, 44.4 months). Patients were telephoned and asked as to whether recurrence occurred, and if so, when it occurred and how it was treated. They were asked to grade their current pain level from 0 to 6. RESULTS Eighty-two patients were contacted, corresponding to 88 video-assisted thoracoscopic surgery pleurodesis procedures that were followed up (80.7%). There were five recurrences (5.7%). The pain level was rated as 0 in 64 cases (72.7%), 1 in 27 cases (23.9%), 2 in 1 case (1.1%), and 3 in 2 cases (2.3%). CONCLUSIONS These data suggest that video-assisted thoracoscopic surgery pleurodesis is a valid alternative to thoracotomy with pleurectomy for treatment of spontaneous pneumothorax with an acceptable recurrence rate and minimal amount of postoperative neuralgia.
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Yang Y, Yan J, Churchwell M, Beger R, Chan P, Doerge DR, Fu PP, Chou MW. Development of a (32)P-postlabeling/HPLC method for detection of dehydroretronecine-derived DNA adducts in vivo and in vitro. Chem Res Toxicol 2001; 14:91-100. [PMID: 11170512 DOI: 10.1021/tx000149o] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyrrolizidine alkaloids are naturally occurring genotoxic chemicals produced by a large number of plants. Metabolism of pyrrolizidine alkaloids in vivo and in vitro generates dehydroretronecine (DHR) as a common reactive metabolite. In this study, we report the development of a (32)P-postlabeling/HPLC method for detection of (i) two DHR-3'-dGMP and four DHR-3'-dAMP adducts and (ii) a set of eight DHR-derived DNA adducts in vitro and in vivo. The approach involves (1) synthesis of DHR-3'-dGMP, DHR-3'-dAMP, and DHR-3',5'-dG-bisphosphate standards and characterization of their structures by mass and (1)H NMR spectral analyses, (2) development of optimal conditions for enzymatic DNA digestion, adduct enrichment, and (32)P-postlabeling, and (3) development of optimal HPLC conditions. Using this methodology, we have detected eight DHR-derived DNA adducts, including the two epimeric DHR-3',5'-dG-bisphosphate adducts both in vitro and in vivo.
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Corselli J, Chan P, et al., Cseh S. Ovarian stimulation and ultrasound-guided oocyte retrieval in baboon (Papio cynocephalus anubis) during pituitary suppression with a gnrh agonist. Acta Vet Hung 2001. [DOI: 10.1556/avet.49.2001.4.8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Chan P, Hsu FL. The in vitro-inhibitory effect of flavonoid astilbin on 3-hydroxy-3-methylglutaryl coenzyme a reductase on vero cells. Heart Lung Circ 2000. [DOI: 10.1046/j.1443-9506.2000.06978.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chan P, Chang JJ, Chen FC, Wu MS, Tomlinson B, Cheng JT. Effects of trilinolein on superoxide dismutase activity and mrna levels in aortic smooth muscle cells. Clin Exp Pharmacol Physiol 2000; 27:1002-6. [PMID: 11117219 DOI: 10.1046/j.1440-1681.2000.03385.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Atherosclerotic cardiovascular disease is still the leading cause of death in Western countries. Oxygen free radicals are considered to be intimately involved in the development of atherosclerosis. Anti-oxidants may help to protect mammalian cells from the damage induced by these reactive oxygen species. Many reports have indicated that anti-oxidants used in the treatment or prevention of disease could modify the levels of superoxide dismutase (SOD). However, the effects of long-term anti-oxidant treatment on the levels of SOD in smooth muscle cells (SMC) is still unclear. In the present study, the effects of the lipophilic anti-oxidant trilinolein on the activity and gene expression of SOD in SMC were evaluated. 2. After 2 days incubation with 0.1 micromol/L trilinolein, the activity and mRNA levels of SOD were increased in rat aortic SMC (A7r5), but there was no significant change in these parameters with a higher concentration of 1 micromol/L trilinolein. 3. In contrast, after 7 days incubation with trilinolein, both the activity and mRNA levels of SOD were lowered in a dose-dependent manner. 4. These data emphasize the importance of choosing an optimal dosage for supplementation with anti-oxidants in humans for the scavenging of oxygen free radicals.
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Chadwick DR, Harrison BJ, Chan P, Chong L, Peachell P. Vasoactive and proliferative effects of parathyroid hormone and parathyroid hormone-related peptide on human vascular smooth muscle. Br J Surg 2000; 87:1529-33. [PMID: 11091241 DOI: 10.1046/j.1365-2168.2000.01575.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Hyperparathyroidism is associated with an increased incidence of hypertension and cardiovascular disease. Experiments in rats suggest that this results from desensitization of the normally inhibitory effects of parathyroid hormone-related peptide (PTHrP) on vascular smooth muscle cells (VSMCs) by previous exposure to parathyroid hormone (PTH). METHODS Isometric tension in vitro was measured in segments of vessels obtained at neck surgery from six normotensive patients with hyperparathyroidism and 12 eucalcaemic controls undergoing thyroid surgery. Vessels were precontracted with noradrenaline to allow the vasodilatory effects of PTH and PTHrP to be observed. Human VSMCs were cultured in 0.5, 5 and 15 per cent serum with or without PTH (10(-11) to 10(-7) nmol l-(1)) and proliferation was assessed by cell counts after 14 days. RESULTS Vasodilatation of arterial segments produced by both PTH 20 nmol l(-1) and PTHrP 100 nmol l(-1) did not differ significantly between control and hyperparathyroidism groups (P > 0.08, Mann-Whitney U test). Vasodilatation by PTHrP was not reduced by preincubation of vessels in vitro with PTH 50 nmol l(-1) for 1 h (P > 0.36, Wilcoxon test). No effects of PTH on serum-induced proliferation of human VSMCs were observed. CONCLUSION These data imply that homologous desensitization to PTHrP is not implicated in the pathogenesis of vascular disease in patients with hyperparathyroidism.
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Wang J, Liu Z, Chan P. Lack of association between cytochrome P450 2E1 gene polymorphisms and Parkinson's disease in a Chinese population. Mov Disord 2000; 15:1267-9. [PMID: 11104220 DOI: 10.1002/1531-8257(200011)15:6<1267::aid-mds1035>3.0.co;2-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Chong NS, Yin WS, Chan P, Cheng MC, Ko HL, Jeng SC, Lee JJ. Evaluation of absorbed radiation dose to working staff during cardiac catheterization procedures. ZHONGHUA YI XUE ZA ZHI = CHINESE MEDICAL JOURNAL; FREE CHINA ED 2000; 63:816-21. [PMID: 11155758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
BACKGROUND Cardiac catheterization has been used frequently for the evaluation and treatment of patients with heart diseases. The working staff, particularly cardiologists who perform these procedures, have the highest potential risk of receiving high radiation doses due to close contact with patients. The purpose of this study was to measure and evaluate the accumulated radiation dosage of the cardiologists while they were performing clinical procedures in the cardiac catheterization laboratory. The working environment of the catheterization laboratory was also monitored for radiation. METHODS Thermoluminescent dosimeters (TLDs) with very high sensitivity were employed for dose evaluations. They were taped to various parts of the body of the cardiologists during catheterization procedures. For environmental monitoring, TLDs were also distributed at several sites of the catheterization rooms for a period of 2 to 4 weeks. RESULTS The study showed that the left wrist of the cardiologists received the highest radiation dose (338 microsieverts [microSv]/procedure) and the left lens received the second highest dose (149 microSv/procedure) during the procedures. The dose to the knees was unexpectedly high (92 microSv/procedure), partly due to radiation leakage from the lead curtain shielding under the patient couch. On average, the effective radiation dose per year was 37 mSv/y for a cardiologist who performs 10 catheterization procedures per week. Compare this to the occupational exposure limit of 50 mSv/y. The estimated accumulated equivalent dose to the lens was 152 mSv/y, which exceeded the regulatory limit for occupational exposure. CONCLUSIONS Using proper lead shielding and increasing the distance from the radiation source are good strategies for reducing the radiation dose in medical staff. The work area outside the catheterization room was considered safe because the radiation level was essentially equivalent to the background radiation level.
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Chan C, Lehmann M, Chan K, Chan P, Chan C, Gruendig B, Kunze G, Renneberg R. Designing an amperometric thick-film microbial BOD sensor. Biosens Bioelectron 2000; 15:343-53. [PMID: 11219747 DOI: 10.1016/s0956-5663(00)00090-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thick film oxygen electrodes manufactured by screen print method have been used as a transducer for a biochemical oxygen demand (BOD) sensor. The kinetics of the immobilized yeast, Arxula adeninivorans (Arxula) has been studied. The apparent KM of immobilized Arxula (> 100 microM) is higher than free cells of Arxula (70 microM). The increase in KM caused by the effect of immobilization extends the linear range of the sensor. End-point measurement and quasi-kinetic measurement have been studied comparatively as measurement procedures with a good correlation. The Vmax for end-point measurement is 790.7 microM/s and that for quasi-kinetic measurement is 537.3 microM/s. The limit of detection is calculated 1.24 mg/l BOD. Using the quasi-kinetic measurement, instead of end-point measurements, the measuring time can be reduced from 5-30 min to 100 s. The sensor layer thickness or increase in the layer of covering gel can increase the KM that is accompanied with the extension of the linear range of the sensor. Nevertheless, increase in the layer of covering gel will not increase the saturation signal. Domestic wastewater was checked by the thick film BOD sensor and the results are satisfactory.
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Chan P, Tomlinson B, Chen YJ, Liu JC, Hsieh MH, Cheng JT. A double-blind placebo-controlled study of the effectiveness and tolerability of oral stevioside in human hypertension. Br J Clin Pharmacol 2000; 50:215-20. [PMID: 10971305 PMCID: PMC2014988 DOI: 10.1046/j.1365-2125.2000.00260.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/1998] [Accepted: 06/15/2000] [Indexed: 11/20/2022] Open
Abstract
AIMS Stevioside is a natural plant glycoside isolated from the plant Stevia rebaudiana which has been commercialized as a sweetener in Japan for more than 20 years. Previous animal studies have shown that stevioside has an antihypertensive effect. This study was to designed to evaluate the effect of stevioside in human hypertension. METHODS A multicentre, randomized, double-blind, placebo-controlled study was undertaken. This study group consisted of 106 Chinese hypertensive subjects with diastolic blood pressure between 95 and 110 mmHg and ages ranging from 28 to 75 years with 60 subjects (men 34, women 26; mean +/- s.d., 54.1+/-3.8 years) allocated to active treatment and 46 (men 19, women 27; mean +/- s.d., 53.7+/-4.1 years) to placebo treatment. Each subject was given capsules containing stevioside (250 mg) or placebo thrice daily and followed-up at monthly intervals for 1 year. RESULTS After 3 months, the systolic and diastolic blood pressure of the stevioside group decreased significantly (systolic: 166.0+/-9.4-152.6+/-6.8 mmHg; diastolic: 104.7 +/- 5.2-90.3+/-3.6 mmHg, P<0.05), and the effect persisted during the whole year. Blood biochemistry parameters including lipid and glucose showed no significant changes. No significant adverse effect was observed and quality of life assessment showed no deterioration. CONCLUSIONS This study shows that oral stevioside is a well tolerated and effective modality that may be considered as an alternative or supplementary therapy for patients with hypertension.
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Nandi PL, Chan JN, Chan CP, Chan P, Chan LP. Undergraduate medical education: comparison of problem-based learning and conventional teaching. Hong Kong Med J 2000; 6:301-6. [PMID: 11025850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
OBJECTIVE To review the literature on studies comparing all aspects of problem-based learning with the conventional mode of teaching. DATA SOURCES Medline literature search (1980 through 1999) and the references cited in retrieved articles. DATA SELECTION Studies and meta-analyses that compared the newer problem-based learning curriculum and the conventional lecture-based mode of teaching undergraduate medical students. Areas of comparison included the academic process; programme evaluation; academic achievement; graduates' performance, specialty choices, and practice characteristics; and the attitude of students and teachers towards the programmes. DATA EXTRACTION Data were extracted independently by multiple authors. DATA SYNTHESIS Students of the problem-based learning curriculum found learning to be "more stimulating and more humane" and "engaging, difficult, and useful", whereas students of the conventional curriculum found learning to be "non-relevant, passive, and boring". Students who used the problem-based learning method showed better interpersonal skills and psychosocial knowledge, as well as a better attitude towards patients. Students using the conventional model, however, performed better in basic science examinations. Teachers tended to enjoy teaching the newer curriculum. Although the two curricula encourage different ways of learning, there is no convincing evidence of improved learning using the problem-based learning curriculum. CONCLUSION A combination of both the conventional and newer curricula may provide the most effective training for undergraduate medical students.
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Tong YC, Wang CJ, Chan P, Cheng JT. Effect of N-(biphenylyl-methyl)imidazole, a type 1 angiotensin II receptor inhibitor, on the contractile function of the rat corpus cavernosum. Urol Int 2000; 64:149-53. [PMID: 10859546 DOI: 10.1159/000030516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effect of N-(biphenylyl-methyl)imidazole, losartan potassium, a newly developed antihypertensive type 1 angiotensin II receptor antagonist on the rat erectile function, was studied. Sexually active 9-week-old male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were given losartan 60 mg/kg intraperitoneal injections. Mean blood pressure (MBP) dropped significantly in both SHR and WKY rats (for SHR: from 140 +/- 8 to 114 +/- 5 mm Hg, p < 0.05, n = 8; for WKY: from 113 +/- 7 to 79 +/- 9 mm Hg, p < 0.05, n = 8). On the contrary, the intracavernous pressure (ICP) of SHR and WKY rats did not differ significantly from that of the corresponding controls receiving saline injections (p > 0.05, n = 8 for each group). For the chronic study, the rats were fed with losartan 30 mg/kg/day for 30 days. MBP decreased significantly in SHR but not in WKY rats (for SHR: from 137 +/- 7 to 113 +/- 5 mm Hg, p < 0.05, n = 8; for WKY: from 110 +/- 6 to 107 +/- 5 mm Hg, p > 0.05, n = 8). The ICP of the losartan-treated rats was not significantly different from that of control rats (p > 0.05, n = 8 for each group). In contrast, WKY rats receiving guanethidine 1 mg/kg/day for 30 days showed significantly decreased ICP. Angiotensin II (10(-9)-10(-5) M) and losartan (10(-9)- 10(-5) M) did not induce significant contractile responses of the cavernosal strip when tested in vitro. On the other hand, methoxamine 10(-4) M induced good contractile responses. In conclusion, the present study demonstrated that angiotensin II did not cause significant change in the contractile status of rat corpus cavernosum. Correspondingly, the type 1 angiotensin II inhibitor effectively lowered blood pressure but did not affect cavernosal contractile function, thus is useful clinically in the treatment of hypertensive disorders without significant detrimental effects on male sexual function.
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