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Biomedical subjects

C L Chan

Publications and source records attributed to C L Chan.

At least 19 recordsLinked to original sources
PubMed2004

Protective effects of Danshensu from the aqueous extract of Salvia miltiorrhiza (Danshen) against homocysteine-induced endothelial dysfunction.

Homocysteine (Hcy) is a by-product of methionine metabolism. An imbalance of Hcy in the body may lead to hyperhomocysteinemia, a condition with elevated Hcy concentration in blood that may be one of the risk factors responsible for the development of several vascular diseases (thromboembolism, atherosclerosis, stroke, vascular diseases and dementia). Radix Salvia miltiorrhiza (Danshen), a well-known Chinese medicinal herb that can activate and improve blood microcirculation, is noticeable for its beneficial effect in treating cardiovascular diseases. The present study is to demonstrate the protective effect of Danshen extract against the homocysteine-induced adverse effect on human umbilical vein endothelial cell (HUVEC). Homocysteine (5 mM) not only decreased the cell viability but also caused the disruption of capillary-like structure formation in vitro. The protective effect of Danshen aqueous extract and its active compounds on endothelial cell function were demonstrated through an in vitro tube formation assay, which mimics the new blood vessel formation. To identify the active components in the aqueous extract of Danshen, the content was characterized by instrumental analysis using high performance liquid chromatography with diode array detector (DAD) and electrospray tandem mass spectrometry (ESI-MS/MS). Interestingly, Danshen extract and its pure compounds showed different effectiveness in protecting HUVEC against Hcy-induced injury according to the following descending order: Danshen aqueous extract, 3-(3,4-dihydroxy-phenyl)-2-hydroxy-propionic acid (Danshensu), protocatechuic acid, catechin and protocatechualdehyde. We believed that such findings might provide evidence in understanding the beneficial effects of Danshen on the cardiovascular system.

Benzaldehydes↗
PubMed2003

Childbirth expectations of Chinese first-time pregnant women.

BACKGROUND: This topic had not been researched previously and the information gained could have implications for midwives working with Chinese women everywhere. AIMS: To explore the specific childbirth expectations of Hong Kong Chinese first-time pregnant women. METHODS: This was a cross-sectional descriptive survey study and a Chinese version of the Childbirth Expectations Questionnaire was used to collect data. The sample consisted of 186 first-time pregnant women who first attended the antenatal clinic at a large public hospital in a major geographical region of Hong Kong. RESULTS: Results showed that the Chinese pregnant women, the majority of who had not attended childbirth education classes, had high expectations of support from both their partners and midwives during labour and delivery. Conversely, expectations toward their own ability to cope with pain were relatively low. In addition, the pregnant women expressed concerns about the severity of labour pain and indicated low expectations about minimal use of medical interventions during labour. CONCLUSIONS: This study results add to the existing literature about childbirth expectations of first-time pregnant Hong Kong Chinese women. Midwife educators should incorporate the findings into childbirth education classes to help pregnant women develop realistic and positive expectations.

Adaptation, Psychological↗
PubMed2001

Synthesis, structural characterization, and photophysics of dinuclear gold(II) complexes [(Au(dppn)Br)(2)](PF(6))(2) and [(Au(dppn)I)(2)](PF(6))(2) with an unsupported Au(II)-Au(II) Bond.

A series of novel dinuclear gold(II) complexes having an unsupported Au(II)-Au(II) bond with well-defined oxidation state at the gold center were synthesized. Red shifts in both the low-energy absorption and emission bands were observed upon increasing the donor ability of the coordinated halogen atoms.

Journal Article↗
PubMed2001

Chinese nasopharyngeal carcinoma patients treated with radiotherapy: association between satisfaction with information provided and quality of life.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is highly prevalent in southern China. Prominent acute side effects of radiotherapy create problems in daily living and working that can generate considerable financial difficulties. A better adjustment to a diagnosis of NPC appears to be associated with an improved rate of recovery, a better quality of life (QoL), a quicker return to work, and normal functioning. Patient satisfaction with physician consultation and the way information is provided in particular may have significant bearing on QoL. The current study reports on short-term QoL after radiotherapy in NPC patients as a function of satisfaction with the information provided. METHODS: Newly referred Hong Kong Chinese NPC patients (n = 211) completed interview measures at baseline before the initiation of radiotherapy, at 4 months after baseline (immediate posttreatment consultation) (FU 1), and again at 8 months (short-term postradiation period) after baseline (FU 2). Satisfaction with the information provided was measured by five items selected from the cognitive subscale of the Medical Interview Satisfaction Scale (MISS). QoL was measured by the Chinese version of the Functional Assessment of Cancer Therapy-General Scale (FACT-G (Ch)). RESULTS: After adjustment for overall patient satisfaction (the PSQ-9), optimism, worry about family, anger, eating ability, subjective health, family income, and occupation at FU 1, treatment between baseline and FU 1, and disease recurrence after baseline, the 5-item MISS at FU 1 (beta = 0.21, P < 0.01) was found to significantly predict patient QoL at FU 2. Adjustment for baseline QoL and disease stage did not appear to alter this relation (beta = 0.20, P < 0.01). CONCLUSIONS: To the authors' knowledge, there is very little research concerning NPC. The results of the current study reinforced the need to improve physicians' information provision during consultations with Chinese NPC patients shortly after the end of treatment.

Analysis of Variance↗
PubMed2001

The anti-initial transcribed sequence, a portable sequence that impedes promoter escape, requires sigma70 for function.

The anti-sequence, a portable element extending from +1 to +15 of the transcript, is sufficient to prevent promoter escape from a variety of strong final sigma70 promoters. We show here that this sequence does not function with even the strongest final sigma32 promoter. Moreover, a particular class of substitutions in final sigma70 that disrupt interaction between Region 2.2 of final sigma70 and a coiled-coiled motif in the beta'-subunit of RNA polymerase antagonizes the function of the anti-element. This same group of mutants prevents lambdaQ-mediated anti-termination at the lambdaP(R') promoter. At this promoter, interaction of final sigma70 with the non-template strand of the initial transcribed sequence (ITS) is required to promote the pause prerequisite for anti-termination. These mutants prevent pausing because they are defective in this recognition event. By analogy, we suggest that interaction of final sigma70 with the non-template strand of the anti-ITS is required for function of this portable element, thus explaining why neither final sigma32 nor the Region 2.2 final sigma70 mutants mediate anti-function. Support for the analogy with the lambdaP(R') promoter comes from preliminary experiments suggesting that the anti-ITS, like the lambdaP(R') ITS, is bipartite.

Base Sequence↗
PubMed2001

Vanilloid receptor 1 immunoreactivity in inflamed human bowel.

Vanilloid receptor 1 (VR1) is expressed by sensory neurons. Once activated, these neurons evoke the sensation of burning pain and release neuropeptides that induce neurogenic inflammation. We used immunoblotting and immunostaining to estimate the density of VR1 in colonic tissues of patients with inflammatory bowel disease and of controls. Our study results indicate that VR1 immunoreactivity is greatly increased in colonic nerve fibres of patients with active inflammatory bowel disease. Thus, the discovery of new drugs that can bind the VR1 receptor, or antagonise endogenous inflammatory substances that activate this receptor, could lead to new therapies for pain and dysmotility.

Humans↗
PubMed2001

ATP-gated ion channel P2X(3) is increased in human inflammatory bowel disease.

P2X(3) is a novel ATP-gated cation channel that is selectively expressed by small-diameter sensory neurones in rodents, and may play a role in nociception by binding ATP released from damaged or inflamed tissues. We have studied, for the first time, P2X(3) immunoreactivity in human inflammatory bowel disease, using Western blotting and immunohistochemistry. A major 66-kDa specific protein was found by Western blotting in all colon extracts. In the inflamed group there was a significant two-fold increase in the relative optical density of the 66-kDa band (21.2 +/- 3.1; n=8) compared to controls (11.4 +/- 3.7; n=8; P=0.009). In the control colon, P2X(3)-immunoreactive neurones were scattered throughout the myenteric and submucosal plexuses, with some neurones showing immunopositive axons/dendrites. The pattern of immunostaining was similar to the neuronal marker peripherin. In general, the intensity of the staining was greater in myenteric than submucosal neurones. The number of P2X(3)-immunoreactive neurones was significantly increased in the myenteric plexus of inflamed colon compared to controls (n=13; P=0.01). In humans, unlike rodents, P2X(3) is thus not restricted to sensory neurones. Increased P2X(3) in inflamed intestine suggests a potential role in dysmotility and pain, for which it represents a new therapeutic target.

Adenosine Triphosphate↗
PubMed2001

Balloon endometrial thermoablation--an alternative management of adenomyosis with menorrhagia and dysmenorrhoea.

A 45 years old Chinese housewife presented with menorrhagia and dysmenorrhoea due to adenomyosis failed to respond to various medical treatments. She was treated with balloon thermoablation. The total menstrual blood loss (MBL) decreased from 96.94 ml before to 37.57 ml, six months after thermoablation. The pictorial blood loss chart (PBLC) showed similar decrease in blood loss. Dysmenorrhoea was also cured. At three year follow up, there was no recurrence. This is the first report which shows thermoablation decreases MBL objectively and can be tried to treat adenomyosis.

Catheterization↗
PubMed2000

Measuring quality of life of Chinese cancer patients: A validation of the Chinese version of the Functional Assessment of Cancer Therapy-General (FACT-G) scale.

BACKGROUND: Few cancer specific quality-of-life (QoL) measures from the West have been translated for use with Chinese-speaking patients, and no substantial validation of these translations with adequately large cohorts has been published previously, to the authors' knowledge. The Functional Assessment of Cancer Therapy-General (FACT-G) is a well-validated QoL instrument that is specific to cancer patients. The scale was translated into Chinese and the psychometric properties of this translated scale (FACT-G [Ch]) were tested with a Chinese sample in Hong Kong, China. METHODS: A total of 1262 Chinese cancer patients were selected in 3 samples from 5 Hong Kong regional hospitals. Quantitative and qualitative data were used to assess the cultural equivalence, factor structure, reliability, and validity of the FACT-G (Ch). RESULTS: Focus group discussions indicated that the FACT-G was seen as covering QoL domains identified as important and relevant to Chinese cancer patients, though in some respects it was seen as having limited scope in this sample. Psychometrically, the factor structure of the FACT-G deviated from that of the original work. The FACT-G (Ch) had acceptable reliability (Cronbach alpha 0.85). The convergent validity of the FACT-G (Ch) with a generic QoL measure (WHOQOL-BREF[HK]) was 0.72 (P < 0.001), and divergent validity showed low correlations of less than 0.15 (P < 0.05) with non-QoL measures. CONCLUSIONS: Focus group data indicated that the FACT-G translation into Chinese was seen as a conceptually relevant and moderately sufficient QoL measure. Psychometrically, the instrument had acceptable properties, but conceptual differences from the original version were suggested. Although more work is needed to increase its adequacy, the translated scale has reasonable utility for use with Chinese populations in clinical settings.

Adult↗
PubMed2000

Characterization of prostanoid receptors mediating inhibition of histamine release from anti-IgE-activated rat peritoneal mast cells.

1. Prostanoid receptors mediating inhibition of anti-IgE induced histamine release from rat peritoneal mast cells have been characterized pharmacologically. PGD2 and the specific DP receptor agonists BW 245C and ZK 118182 were the most potent inhibitors with half-maximal concentrations of 0.26, 0.06 and 0.02 microM respectively. The maximum inhibition attainable was 60-65% with 10(-5) M BW 245C and ZK 118182. 2. Among several EP receptor agonists investigated, only PGE2 and the EP2/EP3 receptor agonist misoprostol induced significant inhibition (46.8 +/- 4.7% at 10(-4) M and 18.7 +/- 6.8% at 10(-5) M respectively). The IP receptor agonists cicaprost and iloprost were both less potent than the DP agonists in inhibiting histamine release (45.2 +/- 3.3% and 35.1 +/- 2.5% inhibition respectively at 10(-5) M), whereas PGF2 alpha and the TP receptor agonist U-46619 were only marginally effective. 3. The EP4/TP receptor antagonist AH 23848 failed to affect the inhibitory actions of PGD2 or PGE2 even at 10(-5) M, whereas the DP/EP1/EP2 receptor antagonist AH 6809 slightly enhanced the effect of PGD2 at 10(-6) M. 4. At concentrations of 3 x 10(-6) to 10(-5) M, the putative DP receptor antagonist ZK 138357 dose-dependently suppressed the inhibitory activities of the DP agonists, PGE2 and cicaprost. The antagonism of ZK 138357 against the DP receptor agonists appeared to be competitive with pA2 values of around six. 5. In conclusion, these data support our earlier proposal that an inhibitory DP receptor is the predominant prostanoid receptor in rat peritoneal mast cell. The properties of this receptor in relation to putative DP receptor subtypes reported in the literature are discussed.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2000

Endoleaks following conventional open abdominal aortic aneurysm repair.

OBJECTIVE: to describe the complication of <<< >>> following conventional open abdominal aortic aneurysm (AAA) repair. DESIGN: prospective case study. SETTING: two specialist vascular surgical centres. PATIENTS AND METHODS: six patients who had successful conventional open AAA repair. RESULTS: six patients presented with back or abdominal pain or hypotension between one and eighteen months later. An endoleak at the distal anastomosis was noted in five of the cases and one endoleak at the proximal anastomosis. All six cases were successfully repaired; two of these patients required Dacron graft replacement, whilst in four cases only direct resuturing was needed. There was no evidence of infection. CONCLUSIONS: an endoleak is not a phenomenon confined to stent grafts. It should be considered in all patients who present with back or abdominal pain within eighteen months of open AAA repair. The combination of computed tomography (CT) scan and digital subtraction angiography is most useful for preoperative diagnosis.

Abdominal Pain↗
PubMed2000

Fogarty balloon dilatation for intraoperative arterial spasm.

OBJECTIVE: to describe an intraoperative technique using a Fogarty balloon to treat arterial spasm following vascular bypass and endarterectomy. DESIGN: prospective case control study. SUBJECTS AND TREATMENT: twenty-two patients following femorodistal bypass surgery and one patient following carotid endarterectomy, with arterial spasm in the distal run-off on completion angiography, were treated with Fogarty balloon dilatation. MATERIALS: Fogarty balloon catheter (Baxtertrade mark). RESULTS: twenty-three patients (100%) with arterial spasm were successfully treated by Fogarty balloon as demonstrated on completion angiography. No complications were seen. CONCLUSION: this simple technique removes vascular spasm rapidly and produces an excellent angiographic result.

Angiography↗
PubMed2000

Liquid chromatography-atmospheric pressure chemical ionization mass spectrometry as a tool for the characterization of anthraquinone derivatives from Chinese herbal medicine.

We have examined the anthraquinone derivatives of a Chinese herb medicine 'Rhubarb' by using HPLC/MS/MS, equipped with an atmospheric pressure chemical ionization source. The simultaneous determination of five ingredients in the sample extracts by HPLC/MS/MS was demonstrated. Product ion spectra of these components in the extracts were obtained and matched against known standards. Concentrations of these active ingredients were estimated by multiple reaction monitoring in the negative ion mode using a single HPLC run.

Anthraquinones↗
PubMed1999

The interface of sigma with core RNA polymerase is extensive, conserved, and functionally specialized.

The sigma subunit of eubacterial RNA polymerase is required throughout initiation, but how it communicates with core polymerase (alpha(2)betabeta') is poorly understood. The present work addresses the location and function of the interface of sigma with core. Our studies suggest that this interface is extensive as mutations in six conserved regions of sigma(70) hinder the ability of sigma to bind core. Direct binding of one of these regions to core can be demonstrated using a peptide-based approach. The same regions, and even equivalent residues, in sigma(32) and sigma(70) alter core interaction, suggesting that sigma(70) family members use homologous residues, at least in part, to interact with core. Finally, the regions of sigma that we identify perform specialized functions, suggesting that different portions of the interface perform discrete roles during transcription initiation.

Amino Acid Sequence↗