Biomedical subjects

P Li

Publications and source records attributed to P Li.

At least 19 recordsLinked to original sources

PubMed2006

Impact assessment of cadmium contamination on rice (Oryza sativa L.) seedlings at molecular and population levels using multiple biomarkers.

Assessment of environmental contamination on ecology (plant) at molecular and population levels is important in risk quantification and remediation study. Random amplified polymorphic DNA (RAPD) assay and related other fingerprinting techniques have been employed to detect the genotoxin-induced DNA damage and mutations. This research compared the effects occurring at molecular and population levels in rice seedlings exposed to cadmium (Cd) concentrations of 15-60 mg l(-1) for 8 days with quartz sand culture. Inhibition of root growth and increase of total soluble protein content in root tips of rice seedlings were observed with the increase of Cd concentration. For the RAPD analyses, 12 RAPD primers of 50-70% GC content were found to produce unique polymorphic band patterns and subsequently were used to produce a total of 180 bands of 179-3056 bp in molecular size in the control root tips of rice seedlings. Results produced by these RAPD primers indicate that changes in RAPD profiles of root tips after Cd treatment include modifications in band intensity and gain or loss of bands by comparison with control. The effect of changes was dose-dependent. Genomic template stability compares favourably with the traditional indices such as root growth and soluble protein content. The DNA polymorphisms detected by RAPD analysis can be applied as a suitable biomarker assay for the detection of genotoxic effects of Cd contamination on plants.

Biomarkers↗

PubMed2006

Rapid eye movement sleep deprivation selectively impairs recall of fear extinction in hippocampus-independent tasks in rats.

Previous studies have shown that rapid eye movement (REM) sleep deprivation (RSD) exerts a detrimental effect on some memory tasks. However, whether post-learning RSD impairs memory for fear extinction, an important model of inhibitory learning, remains to be elucidated. The present study examined the effects of post-extinction RSD from 0 to 6 h and 6 to 12 h on recall of fear extinction tested 24 h after extinction training. We found that RSD from 0 to 6 h significantly increased freezing when recall of extinction of cued fear was tested in the context in which rats received extinction training whereas RSD from 6 to 12 h had no effect (experiments 1 and 2, two hippocampus-independent memory tasks). RSD at either time point had no effect on freezing when recall of extinction of cued fear was tested in the context different from that in which extinction training occurred (experiment 3, a hippocampus-dependent memory task). Additionally, we observed no effect of RSD at either time point on freezing during recall test for extinction of contextual fear (experiment 4, a hippocampus-dependent memory task). These results suggest that the effects of post-extinction RSD on memory for fear extinction are complex. RSD impairs recall of fear extinction in hippocampus-independent tasks, but does not affect recall of fear extinction in hippocampus-dependent tasks. Our findings extend previous research on the effects of RSD on learning and memory and support the notion that REM sleep is involved in memory process of certain tasks.

Acoustic Stimulation↗

PubMed2006

Evaluation of NucliSens EasyQ HIV-1 assay for quantification of HIV-1 subtypes prevalent in South-east Asia.

BACKGROUND: Monitoring anti-retroviral therapy requires that viral load assays for human immunodeficiency virus type 1 (HIV-1) be applicable to diverse HIV-1 subtypes. OBJECTIVES: To evaluate NucliSens EasyQ HIV-1 assay for quantitation of common HIV-1 subtypes prevalent in South-east Asia. STUDY DESIGN: One hundred and nineteen plasma samples collected in Hong Kong and Cambodia were used to compare the performance of NucliSens EasyQ HIV-1 and COBAS Amplicor HIV-1 Monitor version 1.5 assays. Viral RNA extracted from the NucliSens MiniMAG was also used for HIV-1 subtyping. RESULTS: Performance of NucliSens EasyQ correlated well with COBAS Amplicor (r=0.777, p<0.001) and the small mean difference (0.0462log(10)IU/mL) obtained in the Bland and Altman model indicated good agreement between two assays. The NucliSens EasyQ assay demonstrated a 95% sensitivity at 500IU/mL and 100% specificity. Reproducibility of this assay was within log(10)2-4IU/mL and had a coefficient of variation between 2.3% and 10.4%. Among the 109 specimens included in the analysis, HIV-1 subtyping identified 64 CRF01_AE, 38 subtype B, 3 subtype C, 3 CRF07_BC and 1 subtype G viruses. CONCLUSIONS: Performance of NucliSens EasyQ was comparable to COBAS Amplicor for HIV-1 viral load monitoring. RNA extracts from NucliSens MiniMAG could be used for HIV-1 viral load monitoring, subtyping and drug resistance mutations detection. Our findings highlight the versatility of both NucliSens EasyQ and COBAS Amplicor in monitoring prevalent subtypes and rare circulating recombinant forms (CRFs) in the South-east Asia region.

Cambodia↗

PubMed2006

Optimization of pressurized liquid extraction of five major flavanoids from Lysimachia clethroide.

As an alternative of traditional extraction method, pressurized liquid extraction (PLE) was applied for five flavanoids extraction from Lysimachia clethroide. The operational parameters of PLE, such as extraction solvent, temperature, pressure, static extraction time, flush volume and cycles were optimized by univariate approach coupled with central composite design (CCD) in order to obtain the highest extraction efficiency. The optimized result employed 50% acetonitrile aqueous as extraction solvent, 100 degrees C of extraction temperature, 1500 psi of extraction pressure, 25 min of static time, 70% flush volume, and only one cycle to extract the target compounds completely. Finally, the contents of five major flavanoids in L. clethroides from different sources were determined simultaneously by the combination of the presented PLE and HPLC method.

Calibration↗

PubMed2006

Decrease in density of INa is in the common final pathway to heart block in murine hearts overexpressing calcineurin.

Overexpression of calcineurin in transgenic mouse heart results in massive cardiac hypertrophy followed by sudden death. Sudden deaths are caused by abrupt transitions from sinus rhythm to heart block (asystole) in calcineurin-overexpressing (CN) mice. Preliminary studies showed decreased maximum change in potential over time (dV/dt(max)) of phase 0 of the action potential. Accordingly, the hypothesis was tested that decreased activity of the sodium channel contributes to heart block. Profound decreases in activity of sodium currents (I(Na)) paralleled the changes in action potential characteristics. Progressive age-dependent decreases were observed such that at 42-50 days of life little sodium channel function existed. However, this was not paralleled by decreased protein expression as assessed by immunocytochemistry or by Western blot. Since calcineurin can interact with the ryanodine receptor, we assessed whether chronic in vitro treatment with BAPTA-AM, thapsigargin, and ryanodine could rescue the decrease of I(Na). All of these treatments rescued I(Na) to levels indistinguishable from wild type. The nonspecific PKC inhibitor bisindolylmaleimide I also rescued the decrease of I(Na). To assess whether decreased sodium channel activity contributes to sudden death in vivo, the response to encainide (20 mg/kg) was assessed: 6 of 10 young CN mice died because of asystole, whereas 0 of 10 wild-type mice died (P < 0.01). Moreover, encainide produced exaggerated prolongation of the QRS width in sinus beats before the heart block. Catecholamine tone appears necessary to support life in older CN mice because propranolol (1 mg/kg) triggered asystolic death in five of six CN mice. We conclude that decrease in sodium channel activity is in the common final pathway to asystole in CN mice.

Action Potentials↗

PubMed2006

Vif-deficient HIV reverse transcription complexes (RTCs) are subject to structural changes and mutation of RTC-associated reverse transcription products.

Reverse transcription (RTn) in HIV-infected cells occurs in a nucleoprotein complex termed the reverse transcription complex (RTC). RTCs containing RT activity and integrase (IN) were shown to be heterogeneous in size and density on sucrose velocity and equilibrium gradients. WT and Vif-deficient (Deltavif) RTCs produced by infection with virus from permissive cells displayed similar sedimentation characteristics, while RTCs from Deltavif virus produced in non-permissive cells demonstrated a reduction in the major RTC form and more of the RTn products in rapidly sedimenting structures. APOBEC3G derived from virions did not co-sediment with RTCs, but RTCs from Deltavif infections showed elevated levels of mutations in RTn products, consistent with APOBEC3G and other mutational mechanisms. The most mutated transcripts were present within rapidly sedimenting RTCs. Thus, virus without functional vif, produced from non-permissive cells, forms abnormal RTCs that contain increased mutation of RTC-associated RTn products in newly infected target cells.

APOBEC-3G Deaminase↗

PubMed2006

Comparison of haemodynamic responses to orotracheal intubation with GlideScope videolaryngoscope and fibreoptic bronchoscope.

BACKGROUND AND OBJECTIVE: The GlideScope videolaryngoscope is a newly developed laryngoscope for tracheal intubation recently introduced into clinical anaesthesia. In this randomised clinical study, we compared the haemodynamic responses to orotracheal intubation using a GlideScope videolaryngoscope and a fibreoptic bronchoscope. METHODS: Fifty-six adult patients, ASA I-II scheduled for elective plastic surgery under general anaesthesia requiring orotracheal intubation were randomly allocated to either the GlideScope videolaryngoscope group or the fibreoptic bronchoscope group. After a standard intravenous anaesthetic induction, orotracheal intubation was performed. Noninvasive blood pressure and heart rate were recorded before and after induction, at intubation and for 5 min after intubation at 1 min intervals. RESULTS: As compared with the post-induction values the orotracheal intubations using a fibreoptic bronchoscope and a GlideScope videolaryngoscope resulted in the significant increases in blood pressures which did not exceed their baseline values. In the two groups, heart rates at intubation and within 2 min after intubation were significantly higher than their baseline values. However, there were no significant differences in blood pressures and heart rates at all time points, their maximal values and maximal percent changes during the observation and the times required to reach their maximal values between the two groups. CONCLUSIONS: The orotracheal intubations using a fibreoptic bronchoscope and a GlideScope videolaryngoscope produce similar haemodynamic responses.

Adolescent↗

PubMed2006

Simultaneous determination of saponins and fatty acids in Ziziphus jujuba (Suanzaoren) by high performance liquid chromatography-evaporative light scattering detection and pressurized liquid extraction.

The seed of Ziziphus jujube Mill. var. spinosa (Bunge) Hu ex H. F. Chou, Suanzaoren in Chinese, is one of commonly used Chinese medicines. Saponins and fatty oil contains several fatty acids in Suanzaoren are responsible for its therapeutic activities. In this study, a new HPLC coupled with evaporative light scattering detection (ELSD) and pressurized liquid extraction (PLE) method was developed for the simultaneous quantitative determination of 11 major components of 2 saponins and 9 fatty acids, namely jujuboside A, jujuboside B, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, arachidic acid and docosanoic acid in Suanzaoren. Simultaneous separation of these eleven compounds was achieved on a C18 analytical column. The mobile phase consisted of (A) 0.1% aqueous acetic acid and (B) methanol with 0.1% acetic acid using a gradient elution. The drift tube temperature of ELSD was set at 75 degrees C, and nitrogen flow-rate was 1.8l/min. All calibration curves showed good linearity (r(2)>0.9955) within test ranges. This method showed good reproducibility for the quantification of these eleven components in Suanzaoren with intra- and inter-day variations of less than 3.41 and 4.37%, respectively. The validated method was successfully applied to quantify 11 investigated components in nine commercial samples of Suanzaoren.

Calibration↗

PubMed2006

Upregulation and activation of PKC alpha by ErbB2 through Src promotes breast cancer cell invasion that can be blocked by combined treatment with PKC alpha and Src inhibitors.

Although ErbB2 is known to enhance breast cancer metastasis, the signaling events responsible for this remain elusive. Alpha-isozyme of protein kinase C (PKCalpha), which is involved in cancer development and progression, has been suggested to be activated by ErbB2 without direct evidence. In addition, the roles of PKCalpha in ErbB2-mediated cancer cell malignancy have not been clearly identified. In this study, we investigated whether ErbB2 can activate PKCalpha and determined what role PKCalpha plays in ErbB2-mediated breast cancer cell invasion. We expressed wild-type and mutant ErbB2 with altered signaling capacities in MDA-MB-435 breast cancer cells and revealed that overexpression or activation of ErbB2 in MDA-MB-435 cells upregulated and activated PKCalpha and that downregulation of ErbB2 by small-interfering RNA decreased the expression and activity of PKCalpha in BT474 breast cancer cells. These in vitro results were supported by data from breast cancer patient samples. In 150 breast cancer tumor samples, ErbB2-overexpressing tumors showed significantly higher positive rates of PKCalpha membrane immunohistochemistry staining than that of ErbB2-low-expressing tumors. Mechanistically, we found that PKCalpha is co-immunoprecipitated with Src and PKCalpha expression and activity can be decreased by Src inhibitor PP2 and by the expression of a dominant-negative mutant of Src. Moreover, ErbB2-mediated upregulation of urokinase-type plasminogen activator receptor (uPAR) is reduced by either the PKCalpha inhibitor Go6976 or the Src inhibitor PP2, and the combination of Go6976 with PP2 is superior to either agent alone in suppressing uPAR expression and cell invasion. These results demonstrate that PKCalpha is critical for ErbB2-mediated cancer cell invasion and provide valuable insights for current and future PKCalpha and Src inhibitor clinical trials.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2006

The specificity of Sushi peptides for endotoxin and anionic phospholipids: potential application of POPG as an adjuvant for anti-LPS strategies.

Sushi peptides [S1 (Sushi 1 peptide) and S3] are derived from the LPS (lipopolysaccharide; also known as endotoxin)-binding domains of an LPS-sensitive serine protease, Factor C, from the horseshoe crab (Carcinoscorpius rotundicauda). S1 and S3 interact at high affinity with LPS. The intermolecular disulphide bonding in the S3 dimer is indispensable for its LPS binding, disruption and consequent neutralization. Simultaneously, the specific interaction between the Sushi peptides and bacterial membrane phospholipids further explains the selective propensity of these peptides for the gram-negative bacteria. Our findings yield insights into a complex molecular paradigm in which the juxtaposition of LPS molecules and the anionic phospholipid POPG (1-palmitoyl-2-oleoyl phosphatidylglycerol) on the bacterial outer membrane confers such interfacial properties which create the optimal environment for the interaction between the peptides and bacterial membrane lipids.

Adjuvants, Pharmaceutic↗

PubMed2006

Illness-related factors, stress and coping strategies in relation to psychological distress in HIV-infected persons in Hong Kong.

This study examined the relationships among illness-related factors, stress, coping strategies and psychological distress in HIV-infected persons in Hong Kong (N=118). Multiple regression analyses were used to examine the models of psychological distress as a function of demographic factors, illness-related factors, psychosocial stressors and coping. Results showed that positive thinking was inversely related to psychological distress and avoidance was associated with higher level of anxiety. However, the use of problem solving was found to be inversely related to anxiety. Results are discussed in the context of Chinese culture and the service in Hong Kong.

Adaptation, Psychological↗

PubMed2006

Blood pressure and heart rate changes during intubation: a comparison of direct laryngoscopy and a fibreoptic method.

Blood pressure and heart rate changes during nasotracheal intubation under general anaesthesia were studied in 100 patients who were randomly allocated to fibreoptic bronchoscope or direct laryngoscopy intubation. Noninvasive blood pressure and heart rate were recorded before and immediately after anaesthesia induction, at anaesthesia intubation and every minute thereafter for 5 min. Nasotracheal intubation was accompanied by significant increases in blood pressure and heart rate compared to baseline values in both groups. Blood pressure and heart rate at intubation, and the maximum values of blood pressure during the observation were significantly higher in the fibreoptic bronchoscope group. However, the maximum values of heart rate were not significantly different between the two groups. Fibreoptic nasotracheal intubation may result in more severe pressor and tachycardiac responses than direct laryngoscopic nasotracheal intubation.

Adult↗

PubMed2006

Traditional Chinese medicine in cancer care: perspectives and experiences of patients and professionals in China.

Although traditional Chinese medicine (TCM) is widely used in Chinese cancer centres, it is a brand new area for formal scientific evaluation. As the first step of developing a research programme on clinical evaluation of TCM for cancer patients, we conducted a qualitative study to explore the perspectives and experiences of Chinese cancer patients and TCM professionals. Twenty-eight persons participated in two cancer patient focus groups and one professional focus group. Semi-structured interviews were audiotaped, transcribed and translated. Textual transcripts and field notes underwent inductive thematic analysis. We found that patients' decision to use TCM for cancer is a self-help process with a deep cultural grounding, which is related to the traditional Chinese philosophy of life. Participants perceived TCM to be an effective and harmless therapy. They highly valued the fact that TCM is tailored to patients, and believed it was the basis of an optimal and safe treatment. Participants also highlighted the long-term positive effects, the benefit of group interventions and the low cost as important features of TCM. Subjects believed that conducting clinical research would be crucial for the recognition and dissemination of TCM in Western countries. The findings of this study are expected to contribute to the knowledge base on the current TCM use for cancer in China, and to provide useful information for developing future clinical research in this area in Western countries.

Adult↗

PubMed2006

The clinical observation of difficult laryngoscopy and difficult intubation in infants with cleft lip and palate.

BACKGROUND: The aims of this study were to evaluate the incidence of difficult laryngoscopy in infants with cleft lip and palate and to observe its relationships with age, sites, and degrees of deformities. METHODS: A total of 985 infants aged 1 month to 3 years, undergoing repair of cleft lip and palate were included in this study. The infants suffering from unilateral cleft lip, simple cleft palate, and combined bilateral cleft lip and palate were 465, 421, and 79 respectively. They were divided into three groups according to age; 1-6 months group, 6-12 months group and 1-3 years group. RESULTS: The total incidence of difficult laryngoscopy was 4.77%. The incidence of difficult laryngoscopy was closely related to age, sites and degrees of deformities, and micrognathia. The incidence of difficult laryngoscopy was 7.06% in 1-6 months group, 2.90% in 6-12 months group, and 3.13% in 1-3 years group, and was greatest for infants with combined bilateral cleft lip and palate, less for those with left cleft lip and least for those with right cleft lip and simple cleft palate. The incidences of difficult laryngoscopy in infants with and without micrognathia were 50% and 3.83% respectively. The incidences of moderately difficult, difficult, and failed intubations were 1.02%, 0.91%, and 0.102% respectively. CONCLUSIONS: Infants with cleft lip and palate, left cleft lip and alveolus, combined bilateral cleft lip and palate, micrognathia, and age <6 months were the important risk factors for difficult laryngoscopy. Difficult intubation occurred mainly in infants with laryngoscopic views of grade III and IV.

Child, Preschool↗

PubMed2006

A comparative study of hemodynamic responses to orotracheal intubation with fiberoptic bronchoscope and laryngoscope in children.

BACKGROUND: The purposes of this study were to further identify the hemodynamic responses to orotracheal intubation in children, using a fiberoptic bronchoscope (FOB) and a direct laryngoscope (DLS), and to validate whether the FOB can attenuate the hemodynamic response to orotracheal intubation compared with the DLS. METHODS: Forty-three children, ASA PS I-II scheduled for elective plastic surgery under general anesthesia requiring orotracheal intubation were randomly allocated to either the DLS group (n = 20) or the FOB group (n = 23). Noninvasive systolic blood pressure (SBP) and heart rate (HR) were recorded before (baseline values) and after anesthesia induction (postinduction values), at intubation and every minute for the first 5 min after intubation. The maximal values of SBP and HR during the observation were also recorded. The product of HR and SBP [rate pressure product (RPP)] at each time point was calculated. RESULTS: In the DLS group, SBP, HR, and RPP at intubation and 1 min after intubation were significantly higher than postinduction values, but did not exceed baseline values. In the FOB group, SBP, HR, and RPP at intubation increased significantly compared with baseline and postinduction values. In the two groups, the maximal values of SBP, HR, and RPP during the observation were significantly higher than baseline values. Except for the HR at intubation, there were no significant differences in other hemodynamic parameters during the observation and the time required to reach maximal values of SBP, HR, and RPP between the two groups. CONCLUSIONS: Orotracheal intubation using FOB and DLS in children may cause similar increases in SBP and HR. Compared with the DLS, the FOB had no advantage in attenuating the hemodynamic responses to orotracheal intubation.

Anesthesia, General↗

PubMed2006

CCR2 allele polymorphisms in 15 Chinese ethnic populations.

Chemokine receptor-2 (CCR2) is a co-receptor for the entry of human immunodeficiency virus-1 (HIV-1) into the target cells. A mutation in CCR2 (CCR2-64I) exhibited a protective effect to delay the progression of acquired immunodeficiency syndrome (AIDS). To study the mutant frequency and polymorphism of CCR2 in Chinese populations, 1082 individuals from 15 Chinese populations distributing widely from north to south were collected. The genotypes of CCR2-64I were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with the digestion of restriction endonuclease FokI. Of the 1082 individuals, 352 (32.53%) were carriers of CCR2-64I allele, 257 of whom (23.75%) were heterozygotes (CCR2-64V/I), whereas 95 (8.78%) were homozygotes (CCR2-64V/V). The frequency of the CCR2-64I allele in those tested individuals was 20.66%. This prevalence of CCR2-64I was higher than what was known for American and European populations. Moreover, the frequencies of CCR2-64I were generally higher in northern China than they were in southern China, and the frequencies had significant variance in 15 populations of China (chi2 = 27.135, P = 0.018).

Alleles↗

PubMed2006

Cellular interactions of virion infectivity factor (Vif) as potential therapeutic targets: APOBEC3G and more?

Vif is an HIV accessory protein whose primary function is to negate the action of APOBEC3G, a naturally occurring cellular inhibitor of HIV replication. Vif acts by binding to APOBEC3G, inducing its protein degradation within infected cells and reducing its levels in progeny virions. Interventions that interfere with the Vif-APOBEC3G interaction, raise intracellular or virion associated levels of APOBEC3G, or reduce intracellular levels of Vif, all could hold promise as potential therapeutic approaches aimed at enhancing the cells innate antiviral activity. Levels of APOBEC3G might be increased or Vif levels decreased, by strategies targeting protein synthesis, protein degradation or cellular localisation and function, and properties of APOBEC3G and Vif relevant to these strategies are discussed. Recent data have suggested that Vif may have other mechanisms of action apart from the above activities against APOBEC3G, including effects against other anti-viral mechanisms independent of APOBEC3G cytidine deaminase activity. In addition to interaction with APOBEC3G, Vif may have other accessory functions, which are discussed in relation to potential therapies that may affect multiple stages of the HIV life cycle. Future development of strategies that combine enhancement of APBOEC3G functional with inhibition of multiple Vif functions may become useful tools for HIV therapy.

APOBEC-3G Deaminase↗

PubMed2005

Optimization of pressurized liquid extraction for Z-ligustilide, Z-butylidenephthalide and ferulic acid in Angelica sinensis.

Pressurized liquid extraction, one of the most promising and recent sample preparation techniques, offers the advantages of reducing solvent consumption and allowing for automated sample handling. It is being exploited in diverse areas because of its distinct advantages. However, because the extraction is performed at elevated temperatures using PLE, thermal degradation could be a concern. Z-ligustilide, one of the biologically active components in Angelica sinensis, is an unstable compound, which decomposes rapidly at high temperature. In this study, we carried out a comparative study to evaluate PLE as a possible alternative to current extraction methods like Soxhlet and sonication for simultaneous extraction of Z-ligustilide, Z-butylidenephthalide and ferulic acid in A. sinensis. The operating parameters for PLE including extraction solvent, particle size, pressure, temperature, static extraction time, flush volume and numbers of extraction were optimized by using univariate approach coupled with central composite design (CCD) in order to obtain the highest extraction efficiency. Determination of Z-ligustilide, Z-butylidenephthalide and ferulic acid were carried out by means of high performance liquid chromatography with diode-array detector. The results showed that PLE was a simple, high efficient and automated method with lower solvent consumption compared to conventional extraction methods such as Soxhlet and sonication. PLE could be used for simultaneous extraction of Z-ligustilide, Z-butylidenephthalide and ferulic acid in A. sinensis.

4-Butyrolactone↗