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Biomedical subjects

Peng Li

Publications and source records attributed to Peng Li.

At least 91 records · Page 5Linked to original sources
PubMed2005

Simultaneous determination of anthraquinones in Rhubarb by pressurized liquid extraction and capillary zone electrophoresis.

Rhubarb, a well-known Chinese herbal medicine, is also used in Europe and other places of the world. Anthraquinones derivatives are thought to be the major active components. A pressurized liquid extraction (PLE) and capillary zone electrophoresis (CZE) separation were developed for simultaneous determination of five anthraquinones including aloe-emodin, emodin, chrysophanol, physcion, and rhein in Rhubarb. The effects of the experimental variables on PLE and CZE have been optimized. The optimum conditions of PLE were: solvent, methanol; temperature, 140 degrees C; particle size, 0.13-0.2 mm; static extraction time, 5 min; pressure, 1500 psi; and one extraction. The best separation of the five anthraquinones could be obtained using 50 mM borate buffer (pH 8.2) containing 25% isopropyl alcohol and 25% acetontrile as modifier, while the separation voltage was 25 kV and the temperature was at 20 degrees C. The method developed is accurate, simple, and reproducible, and could be used for quality control of Rhubarb and its medical preparations.

Anthraquinones↗
PubMed2005

Comparison of surgical stress between laparoscopic and open appendectomy in children.

PURPOSE: The present study aimed to evaluate laparoscopic appendectomy (LA) in comparison with conventional open appendectomy (OA) in children, with special emphasis on the extent of surgical trauma after LA and OA, and to assess whether LA had any clear advantages compared with conventional OA. METHODS: A total of 160 patients with a median age of 7.9 years (range 3-15 years) were studied. Sixty-nine of them underwent LA, and the remaining 91 underwent OA. Serum interleukin (IL) 6 and C-reactive protein (CRP) levels which are thought to play a pivotal role in the pathogenesis of surgical trauma and can also be used to monitor the magnitude of surgical trauma were measured using an enzyme-linked immunosorbent assay before surgery and 12 hours after surgery. In addition, we compared operating time, hospital stay, incidence of wound infection, and incidence of intra-abdominal infection. RESULTS: The operative time of normal and suppurative appendix in the laparoscopic group was significantly shorter than that in the open group, respectively, but the operative time of gangrenous appendix was not different between the laparoscopic group and open group. The hospital stay in the laparoscopic group was also significantly shorter than that in the open group. Postoperatively, 1 patient had port-site infection in the laparoscopic group, whereas 10 had wound infection in the open group; this difference was highly significant (chi2 = 4.19, P < .05). Three patients in the open group and 2 patients in the laparoscopic group had intra-abdominal infection, and the difference had no statistically significant difference (chi2 = 0.10, P < .05). Preoperative IL-6 levels were not different between the 2 groups, but the rise (preoperative vs postoperative) of IL-6 in the laparoscopic group was remarkably less than that in the open group. Similar results were obtained for CRP; serum CRP levels in the basal state were not different between the 2 groups, but the rise (preoperative vs postoperative) of CRP in the laparoscopic group was also substantially less compared with that in the open group. CONCLUSIONS: LA for children was as safe and effective as the open procedure and had significant advantages over OA because of less operating time, less postoperative complications, less surgical trauma, and more rapid postoperative recovery.

Adolescent↗
PubMed2005

Histological characterization of microlesions induced by myocardial contrast echocardiography.

BACKGROUND: Myocardial contrast echocardiography (MCE) has been shown to have a potential for apparently reversible side effects related to the interaction of ultrasound with the contrast microbubbles, including premature ventricular contractions and microvascular leakage. We investigated the potential for high-dose MCE to induce histologically definable microlesions. METHODS: Myocardial contrast echocardiography with 1:4 end-systolic triggering was performed at 1.5 MHz and 1.7 mechanical index in a short axis view of the left ventricle in rats. Two high doses (500 microl/kg) of Optison agent were given 5 minutes apart during 10 minutes of echocardiography. For histology, the hearts were perfused and fixed in 10% neutral-buffered formalin. Slides from rats sacrificed 1 day after MCE were scored blind by a pathologist, and, in addition, photomicrographs in the anterior half were evaluated by digital image analysis. RESULTS: In rats sacrificed 10 minutes after MCE, microvascular leakage and petechiae were highly significant. However, lesions displaying necrotic debris associated with inflammatory infiltrates were not histologically evident at this time. Heart samples 24 hours after MCE showed microlesions with inflammatory infiltrates scattered primarily over the anterior half of the sections. Pathologically, there was inflammatory cell infiltration in areas of 0.6 +/- 0.5% for shams and 3.6 +/- 3.6% for MCE (P < 0.01). Analysis of photographs from the anterior wall found microlesion areas of 0.5 +/- 0.8% for shams and 7.4 +/- 5.0% for MCE (P < 0.02). For rats sacrificed 1 week and 6 weeks after MCE, the microlesions healed to form small fibrous regions interspersed with normal myocytes. CONCLUSION: High-dose MCE has a potential for causing microscale lesions in the myocardium and the possibility of therapeutic applications.

Albumins↗
PubMed2005

Hypoxia inhibits the migratory capacity of human monocyte-derived dendritic cells.

Hypoxia, a prominent characteristic of inflammatory tissue lesions and solid tumour microenvironments, is a crucial stimulus capable of modulating the expression of specific genes involved in leucocyte recruitment. Although studies have shown that hypoxia can affect leucocyte migration by influencing the expression of migration-related genes, such as matrix metalloproteinases (MMP) and their endogenous tissue inhibitors of matrix metalloproteinases (TIMP), it remains unclear whether hypoxia can affect the migration of dendritic cells (DC). In this study, we showed that human monocyte-derived DC under hypoxic conditions in a transwell system have significantly reduced migratory capacity compared to normoxic controls. A moderate phenotypic change of hypoxic DC was observed. In hypoxic DC, we detected a twofold increase in TIMP-1 transcript levels, and downregulated expression of MMP-9 and membrane type 1-MMP genes by threefold and 17-fold, respectively. Our results suggest that hypoxia may inhibit DC migratory activity by regulating the balance between MMP and TIMP gene expression.

Cell Differentiation↗
PubMed2005

Exploring the diversity of myxobacteria in a soil niche by myxobacteria-specific primers and probes.

The diversity of myxobacteria in a soil niche was explored using culture-dependent and -independent methods. Conventional cultivation for bacteriolytic myxobacteria produced six types of myxobacteria, which were identified as two Myxococcus spp., two Corallococcus spp., a Cystobacter sp. and a Nannocysts sp. Hybridization analysis of the soil bacterial 16S rRNA gene library with myxobacteria-specific probes revealed that myxobacteria accounted for less than 1% in the bacterial community. A Cystobacterineae 16S rRNA genes-rich library was further established from the soil DNA by polymerase chain reaction amplification with a Cystobacterineae-specific primer combined with a universal bacterial primer. Screening of the special library using Cystobacterineae- and Sorangineae-specific probes produced approximately 45% and 3% positive signals respectively. Sixty-four positive clones were randomly selected for sequencing. Except three repeats, the sequences were diverse ranging from 0.3% to 21.3%, and homologous with the known myxobacteria at 77.6-99.8%, including 57 in Cystobacterineae, one close to Nannocystis and three much more distant from the known myxobacteria. The sequences in the Cystobacterineae can further be divided into at least 12 groups, of which most were unreported. The results suggest that myxobacteria in nature are much more diverse than were ever known, even in one soil niche.

Culture Media↗
PubMed2005

The critical role of calpain versus caspase activation in excitotoxic injury induced by nitric oxide.

The pathogenesis of various acute and chronic neurodegenerative disorders has been linked to excitotoxic processes and excess generation of nitric oxide. We investigated the deleterious effects of calpain activation in nitric oxide-elicited neuronal apoptosis. In this model, nitric oxide triggers apoptosis of murine cerebellar granule cells by an excitotoxic mechanism requiring glutamate exocytosis and receptor-mediated intracellular calcium overload. Here, we found that calcium-dependent cysteine proteases, calpains, were activated early in apoptosis of cerebellar granule cells exposed to nitric oxide. Release of the proapoptogenic factors cytochrome c and apoptosis-inducing factor from mitochondria preceded neuronal death. However, caspases-3 was not activated. We observed that procaspase-9 was cleaved by calpains to proteolytically inactive fragments. Inhibition of calpains by different synthetic calpain inhibitors or by adenovirally mediated expression of the calpastatin inhibitory domain prevented mitochondrial release of cytochrome c and apoptosis-inducing factor, calpain-specific proteolysis and neuronal apoptosis. We conclude that (i) signal transduction pathways exist that prevent the entry of neurons into a caspase-dependent death after mitochondrial release of cytochrome c and (ii) that calpain activation links nitric oxide-triggered excitotoxic events with the execution of caspase-independent apoptosis in neurons.

Animals↗
PubMed2005

Rate-dependent AV delay optimization in cardiac resynchronization therapy.

BACKGROUND: During cardiac resynchronization therapy (CRT), cardiac performance is dependent on an optimized atrioventricular delay (AVD). However, the optimal AVD at different heart rates has not been defined yet during CRT. METHOD: The effects of an increase in heart rate by pacing or physical exercise on optimal AVD were studied in 36 patients with biventricular pacemakers/defibrillators. The velocity time integral (VTI) in the left ventricular outflow tract (LVOT) was measured with pulsed Doppler either at three different paced heart rates in the supine position or in seated position before and after physical exercise. RESULTS: The baseline AVD was optimized to 99 +/- 19 ms in the supine and 84 +/- 22 ms in the seated position. When the heart rate was increased by DDD pacing, there was a positive linear relationship between an increase in heart rate, in AVD and in VTI (LVOT-VTI + 0.047 cm/s per 10 beats per minute (bpm) heart rate increase per 20 ms increase in AVD, P = 0.007). A similar but more pronounced relationship was found after physical exercise in the seated position (LVOT-VTI + 0.146 cm/s per 10 bpm heart rate increase per 20 ms increase of AVD, P = 0.013). This effect was observed in patients with and without AV block and mitral regurgitation. CONCLUSIONS: In conclusion, the systolic performance of the dilated ventricle, which depends on an elevated preload, is critically affected by the appropriate timing of the AVD during exercise. In contrast to normal pacemaker patients, in CRT the relatively short baseline AVD should be prolonged at increased heart rates. Further studies with other means of measuring exercise cardiac performance are needed to confirm these unexpected findings.

Atrioventricular Node↗
PubMed2005

Effect of cardiac resynchronization therapy on longitudinal and circumferential left ventricular mechanics by velocity vector imaging: description and initial clinical application of a novel method using high-frame rate B-mode echocardiographic images.

Cardiac resynchronization therapy (CRT) has emerged as an important method to treat patient with symptomatic heart failure with evidence of intraventricular dyssynchrony. Tissue Doppler imaging by echocardiography has been shown to be an excellent tool for the assessment of mechanical left ventricular dyssynchrony and the selection of patients for CRT. However, there are some patients who do not show symptomatic improvement following CRT. One possible explanation for this is the need to optimize not only longitudinal synchrony, but also improve the circumferential and radial dynamics of the left ventricle. Doppler imaging does not allow reliable assessment of the latter because of the angle-dependency of the technique. Velocity Vector Imaging (VVI) is a newer technique which is angle-independent and thus provides an avenue to evaluate short-axis mechanics of the left ventricle. We describe a case in which VVI was used to assess the left ventricular dynamics in a patient with heart failure who did not respond to CRT.

Algorithms↗
PubMed2005

Influence of contrast agent dose and ultrasound exposure on cardiomyocyte injury induced by myocardial contrast echocardiography in rats.

PURPOSE: To detect specific cardiomyocyte injury induced by myocardial contrast material-enhanced echocardiography (ie, myocardial contrast echocardiography) in rats and to ascertain the influences of contrast material dose and ultrasound exposure on this injury. MATERIALS AND METHODS: All animal procedures were approved by the university committee for the use and care of animals. Myocardial contrast echocardiography with 1:4 electrocardiographic (ECG) triggering was performed at 1.5 MHz in 61 anesthetized rats. Evans blue (EB) dye was injected as the vital stain for cardiomyocyte injury. At the start of myocardial contrast echocardiography, which lasted 10 minutes, perflutren lipid microsphere-based contrast material was infused through the tail vein for 5 minutes. Premature heartbeats were counted from the ECG record. The numbers of EB-stained cells counted on sections of heart specimens obtained 24 hours after myocardial contrast echocardiography and then either fresh frozen or embedded in paraffin were determined by using fluorescence microscopy. Results were compared statistically by using t tests and Mann-Whitney rank sum tests. RESULTS: EB-stained cells were concentrated in the anterior region of the myocardium. In the paraffin-embedded specimens, EB-stained cells were often accompanied by but largely separate from areas of inflammatory cell infiltration. At end-systolic triggering with a 50 microL/kg dose of microsphere contrast material, the EB-stained cell count increased with increasing peak rarefactional pressure amplitude, with significantly increased cell counts at 1.6 MPa (P < .02) and 2.0 MPa (P < .005) relative to the cell counts at sham myocardial contrast echocardiography. Premature heartbeats had a similar exposure-response relationship; however, number of premature heartbeats and EB-stained cell count did not appear to be directly related (coefficient of determination r2 = 0.03). The EB-stained cell counts at end-diastolic triggering were not significantly different from those at end-systolic triggering (P > .1). EB-stained cell counts increased with increasing contrast material dose, from 10 to 50 microL/kg, at 2.0 MPa. CONCLUSION: Cardiomyocyte injury was induced by the interaction of ultrasound pulses with contrast agent microbubbles during myocardial contrast echocardiography in rats, and the numbers of injured cells increased with increasing contrast agent dose and ultrasound exposure.

Animals↗
PubMed2005

A dammarane glycoside derived from ginsenoside Rb3.

A dammarane glycoside, designated compound Mx (C-Mx), was isolated from the hydrolysate of 20(S)-protopanaxadiol type ginsenosides containing G-Rb(3) from Panax notoginseng leaves with crude snailase. Its chemical structure was elucidated to be 20-O-beta-D-xylopyranosyl(1-->6)-beta-D-glucopyranosyl-20(S)-protopanaxadiol on the basis of spectral analysis. Its cytotoxicity against breast cancer cell line MCF-7 and effects on the sensitivity to doxocubicin of doxocubicin-resistant MCF-7 cells were also investigated. The new compound showed moderate cytotoxicity and partial reversal of doxocubicin resistance.

Anti-Bacterial Agents↗
PubMed2005

Novel potato micro-tuber-inducing compound, (3R,6S)-6-hydroxylasiodiplodin, from a strain of Lasiodiplodia theobromae.

A novel potato micro-tuber-inducing compound was isolated from the culture broth of Lasiodiplodia theobromae Shimokita 2. The structure of the isolated compound was determined as (3R,6S)-6-hydroxylasiodiplodin by means of spectroscopic analyses, the modified Mosher method, and chemical conversion. The compound showed potato micro-tuber-inducing activity at a concentration of 10(-4) M, using the culture of single-node segments of potato stems in vitro.

Ascomycota↗
PubMed2005

[The prokaryotic expression and the establishment of the putative indirect ELISA assay for the HA gene for avian influenza virus (AIV) H5N1 subtype].

Using a pair of specific primers designed according to the relevant nucleotide sequence from GenBank, the HA1 gene of H5N1 subtype AIV was amplified with PCR method. The PCR product was cloned into pET-32a(+) to get a prokaryotic recombinant plasmid pET-HA1. The target gene was successfully expressed in the host cell BL21 (DE3) when induced with IPTG. The expression was optimized with proper inducing conditions of 0.8 mmol/L IPTG and 3 hours induction. The highest expression of the target protein added up to 32.7% of the total bacterial protein. Western blot analysis proved the recombinant protein has good reactive ability against H5N1 subtype AIV positive serum. The optional working circumstances for the iHA-ELISA assay (antigenicity concentration: 4 microg/mL; serum dilution: 1:200) was tried out with chess titration. The positive criterion of this ELISA assay is OD(the tested serum) > 0.5 and OD(the tested serum)/OD(the negative serum) > 2.0.

Animals↗
PubMed2005

Differentiation of mesenchymal stem cells into dopaminergic neuron-like cells in vitro.

OBJECTIVE: To explore the way to induce mesenchymal stem cells (MSCs) to differentiate into dopaminergic neurons in vitro. METHODS: MSCs were obtained from rat bone marrow, cultured and passaged. MSCs used in this experiment had multipotency, which was indirectly proved by being induced to differentiate into chondrocytes and adipocytes. MSCs were cultured in medium containing 0.5 mmol/L IBMX for 2 days. Then the medium was replaced with induction medium, which contained GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments. The surface markers of the differentiated neurons, such as NSE, nestin, MAP-2a, b and TH were detected by immunocytochemistry and Western blot after MSCs were cultured in induction medium for 7 days and 15 days. RESULTS: MSCs differentiated into neural progenitors and expressed nestin after MSCs were incubated with medium containing IBMX for 2 d. After the medium was replaced with induction medium containing many inducing agents, MSCs differentiated into neuron-like cells and dopaminergic neuron-like cells and expressed NSE, MAP-2a, b and TH. The percentage of NSE-positive cells, MAP-2a, b-positive cells and TH-positive cells was 30.032 +/- 2.489%, 41.580 +/- 5.101% and 34.958 +/- 5.534%, respectively after MSCs were induced in medium containing GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments for 15 days. CONCLUSION: MSCs can differentiate into dopaminergic neuron-like cells and are a new cell source for the treatment of neurodegeneration diseases and have a great potential for wide application.

Adipocytes↗
PubMed2005

[Epidemiological investigation on congenital heart disease in several regions of Yunnan province].

OBJECTIVE: To investigate the distribution of congenital heart disease (CHD) aged 3 - 18 in several regions of Yunnan province. METHODS: Cross-rectional studies were carried out among 48 638 children from Xishuangbanna, Dali, Baoshan Longling, Luxi Mangshi and Gejiu in Yunnan province with stratified, clustered sampling. RESULTS: The overall morbidity of CHD was 5.08 per thousand with 5.09 per thousand in males and 5.07 per thousand in females. Morbidity rates in different regions were 2.75 per thousand in Xishuangbanna, 7.85 per thousand in Dali, 9.59 per thousand in Baoshan Long ling, 4.80 per thousand in Gejiu, 16.99 per thousand in Luxi Wuchalu. However, in the same area, rates were different among different residents:3.25 per thousand in Gejiu, and was 9.10 per thousand in Laochang stannum mine, 11.20 per thousand in Datunxuanchang; 5.74 per thousand at the city of Baoshan Longling, 11.35 per thousand at countryside; 4.90 per thousand at the city of Dali, 8.71 per thousand at countryside; 1.69 per thousand at the city of Xishuangbanna, 4.40 per thousand at country. Morbidity rates in different ethnic groups were as follows: 5.39 per thousand in Dai, 6.83 per thousand in Jinuo, 0 per thousand in Hani, 8.12 per thousand in Bai, 14.18 per thousand in Jingpo. CONCLUSION: There were significant regional and ethnic differences seen in Yunnan on the mobidity of CHD which was different from the domestic literature reported.

Adolescent↗
PubMed2005

[Dynamic distribution characters of herbaceous vegetation root systems in abandoned grasslands of Loess Plateau].

The investigation on the vertical distribution characters of herbaceous vegetation root systems in abandoned and natural grasslands of Loess Plateau by the method of soil auger showed that there were no significant differences in root system distribution patterns between different sampling points, and the related root indexes could be used to indicate the vertical distribution characters of vegetation roots. The main root indexes including root biomass and root length were decreased with increasing soil depth, but increased with increasing abandoned years. After abandoned for more than 20 years, the root distribution characters of abandoned grassland were approached to that of natural grassland. The root extinction coefficient decreased with increasing abandoned years, indicating that more and more roots were concentrated in surface soil layer with the increase of abandoned time, which was helpful to the improvement of soil physical and chemical properties, and beneficial to the new species intrusion and vegetation succession.

Biomass↗
PubMed2005

[Experimental investigation of effects of adenovirus transduced tissue factor pathway inhibitor-2 gene on growth of laryngeal squamous carcinoma].

OBJECTIVE: To investigate the inhibitory effects of adenovirus transduced TFPI-2 gene on the growth of laryngeal squamous carcinoma. METHODS: Recombinant adenoviruses carrying human TFPI-2 gene were amplified and identified. The nude mouse model of laryngeal squamous carcinoma was established by intracutaneous injection of Hep-2 cells. Mice in the treated group were injected with recombinant adenoviruses with Ad-TFPI-2 (adenoviruses-TFPI-2) in peritumor tissue while mice in control group were injected with equivalent null plasmids. After treatment, the tumor weight and volume of tumor in each mouse were measured respectively. The morphological changes of tumor cells were observed using transmission electron microscope and proliferating cell nuclear antigen (PCNA) expression was examined using immunohistochemistry. RESULTS: The Ad-TFPI-2 virus titer was 2.8 x 10(12) PFU/ml after amplification. The average tumor weight and volume in Ad-TFPI-2 treated group were (1.20 +/- 0.34) cm3 and the volume (1.52 +/- 0.39) g, which were significantly lower than the tumor weight (2. 08 +/- 0.52) cm3 and (2.67 +/- 0.47) g in the control group (P < 0. 01). Apoptosis was observed in the tumors of Ad-TFPI-2 treated group. The PCNA index in Ad-TFPI-2 group was (54.9% +/- 12.4%), which was obviously lower than that (75.8% +/- 11.2%)in control group (P < 0.01). CONCLUSION: Peritumor injection of Ad-TFPI-2 can inhibit the growth of laryngeal squamous carcinoma in nude mouse model.

Adenoviridae↗
PubMed2005

[Experimental study on induction of the normal human melanocytes apoptosis in vitro by cycloheximide and TNF-alpha].

OBJECTIVE: To investigate the effects of cycloheximide and TNF-alpha on melanocyte (MC). METHODS: Melanocyte apoptosis was studied with MTT, transmitting electron microscopy and fluorescence labeling of alive cells. RESULTS: We added TNF-alpha and cycloheximide in melanocytes, and the typical apoptosis appeared 24 hours later, with chromatin condensation, nuclear pyknosis and apoptotic bodies formation. The results of cytometry showed the typical apoptotic peak. CONCLUSION: TNF-alpha and cycloheximide together could inhibit MC proliferation and induce MC apoptosis.

Adolescent↗