Biomedical subjects

Chao Li

Publications and source records attributed to Chao Li.

62 records · Page 4Linked to original sources

PubMed2003

[Endovascular stent-graft repair of aortic arch aneurysms: report of 46 patients].

OBJECTIVE: To evaluate the basic procedure of endovascular stent-graft repair in the treatment of aortic arch aneurysm. METHODS: >From March 2000-February 2002, a total of 46 patients with aortic arch aneurysms were treated with the custom-made endovascular stent-graft. Of them, twenty-three patients (50%) had aneurysms at the middle of the arch, 22 patients (48%) had aneurysms at the arch-descending aorta, and 1 patient (2%) had aneurysm at the descending thoracic aorta. The diameter of all stents was 0.15 - 0.25 times larger than that of the aorta proximal to the entry tear of dissection or the opening of aneurysm. The diameter of the proximal end of the stents was ranged from 34 - 38 mm. The length of stents ranged from 90 - 120 mm. The stent was made of shape memory nitinol. RESULTS: The stent was delivered successfully in 45 patients (98%). None of the patients had any access-related complications. Either the primary entry tear of aortic dissection or the inlet of aneurysm was occluded in 43 patients (96%), with an early endoleak in 2 patients (4%). All truth lumen of the dissection recovered to normal. Of the patients in acute period, 1 was referred to surgical repair and 2 died. Follow-up for 1 month to 23 months, showed late endoleak in 3 patients (7%). Forty-three patients restored normal life. CONCLUSIONS: Endovascular stent-graft could be applied in the repair of aortic arch aneurysm. Further studies are needed to to assess the long-term efficacy of this method.

Adult↗

PubMed2002

Differential expression and regulation by 20-hydroxyecdysone of mosquito ecdysteroid receptor isoforms A and B.

Cloning of the AaEcR-A isoform, along with the previously cloned AaEcR-B isoform, has permitted us to evaluate the expression of AaEcR isoforms during mosquito vitellogenesis. Mosquito EcR isoform transcripts exhibited dramatically different patterns of expression after a blood meal-triggered activation of vitellogenesis in the fat body. The AaEcR-B transcript level rose sharply by 4-h post blood meal (PBM), coinciding with the small ecdysteroid peak, and then declined reaching its lowest level at 16-24-h PBM. In contrast, the AaEcR-A transcript peaked at 16-20-h PBM, coinciding with the large ecdysteroid peak. AaEcR-B and AaEcR-A transcripts exhibited a striking difference in sensitivity to 20-hydroxyecdysone (20E), being maximally activated at 10(-8) and 10(-6) M, respectively. Both ecdysteroid receptor (EcR) isoform mRNAs were transcribed in a cycloheximide-independent manner, suggesting that they are direct targets of 20E. However, AaEcR-A transcription requires continuous presence of 20E, while AaEcR-B mRNA level rose for 4 h and then declined under the same conditions. These results indicate the mosquito EcR isoforms play distinct physiological functions during vitellogenesis in the mosquito fat body.

Animals↗

PubMed2002

Two isoforms of the early E74 gene, an Ets transcription factor homologue, are implicated in the ecdysteroid hierarchy governing vitellogenesis of the mosquito, Aedes aegypti.

In the anautogenous mosquito, Aedes aegypti, vitellogenesis is under the strict control of 20-hydroxyecdysone (20E), which is produced via a blood meal-activated hormonal cascade. Several genes of the ecdysteroid-regulatory hierarchy are conserved between vitellogenesis in mosquitoes and metamorphosis in Drosophila. We report characterization of two isoforms of the mosquito early E74 gene (AaE74), which have a common C-terminal Ets DNA-binding domain and unique N-termini. They exhibited a high level of identity to Drosophila E74 isoforms A and B and showed structural features typical for Ets transcription factors. Both mosquito E74 isoforms bound to an E74 consensus motif C/AGGAA. In the fat body and ovary, the transcript of AaE74 isoform homologous to Drosophila E74B was induced by a blood meal exhibiting its highest level coinciding with the peak of vitellogenesis. In contrast, the transcript of AaE74 isoform homologous to Drosophila E74A was activated at the termination of vitellogenesis. These findings suggest that AaE74A and AaE74B isoforms play different roles in regulation of vitellogenesis in mosquitoes.

Aedes↗

PubMed2002

Molecular biology of mosquito vitellogenesis: from basic studies to genetic engineering of antipathogen immunity.

Elucidation of molecular mechanisms underlying stage- and tissue-specific expression of genes activated by a blood meal is of great importance for current efforts directed towards utilizing molecular genetics to develop novel strategies of mosquito and pathogen control. Regulatory regions of such genes can be used to express anti-pathogen effector molecules in engineered vectors in a precise temporal and spatial manner, designed to maximally affect a pathogen. The fat body is a particularly important target for engineering anti-pathogen properties because in insects, it is a potent secretory tissue releasing its products to the hemolymph, an environment or a crossroad for most pathogens. Recently, we have provided proof of this concept by engineering stable transformant lines of Aedes aegypti mosquito, in which the regulatory region A. aegypti vitellogenin (Vg) gene activates high-level fat body-specific expression of a potent anti-bacterial factor, defensin, in response to a blood meal. Further study of the Vg gene utilizing Drosophila and Aedes transformation identified cis-regulatory sites responsible for state- and fat body-specific activation of this gene via a blood-meal-triggered cascade. These analyses revealed three regulatory regions in the 2.1-kb upstream portion of the Vg gene. The proximal region, containing binding sites to EcR/USP, GATA, C/EBP and HNF3/fkh, is required for the correct tissue- and stage-specific expression at a low level. The median region, carrying sites for early ecdysone response factors E74 and E75, is responsible for a stage-specific hormonal enhancement of the Vg expression. Finally, the distal GATA-rich region is necessary for extremely high expression levels characteristic to the Vg gene. Furthermore, our study showed that several transcription factors involved in controlling the Vg gene expression, are themselves targets of the blood meal-mediated regulatory cascade, thus greatly amplifying the effect of this cascade on the Vg gene. This research serves as the foundation for the future design of mosquito-specific expression cassettes with predicted stage- and tissue specificity at the desired levels of transgene expression.

Aedes↗

PubMed2002

The second National Epidemiological Survey on illicit drug use at six high-prevalence areas in China: prevalence rates and use patterns.

AIMS: This is the first part of the Second National Epidemiological Survey on Illicit Drug Use in six high-prevalence areas in China in 1996. The scale of illicit drug abuse and patterns of use in the survey areas were assessed. DESIGN, SETTING AND PARTICIPANTS: 67 319 registered permanent residents in the community and those who were at institutions at the point of the survey (15 years old and over, males 34 755, 51.6%; females 32 564, 48.4%) in selected areas in China were screened and interviewed by trained psychiatrists. MEASUREMENTS: Demographics and drug-related data were assessed using the Epidemiological Inventory for Illicit Drug Use developed by the authors. Illicit drugs in this study were defined as a group of psychoactive substances controlled by international and national laws, used for non-medical purposes, including opiate, cocaine, amphetamine-type stimulants (ATS), cannabis, hallucinogens, etc. FINDINGS: The lifetime prevalence of illicit drug use was 1.60% (male, 2.58%, female 0.57%), and 1-year prevalence was 1.17% (male 1.80%, female 0.48%). There were 67 cases who used a drug initially before 1952; no new cases of illicit drug use could then be found during the period of 1952-86. However, the number of new drug users in each year has been rising steadily since 1986. The majority of drugs used were opiates in which heroin dominated, although there was some variability among the six sites. The main routes of administration were inhalation and intravenous injection. More than half the users (59.1%) took drugs on seven occasions or less per week, and 15.8% users used drugs on 21 occasions or more per week. CONCLUSION: Compared with the data from the 1993 survey, illicit drug use has continued to escalate across the areas, calling for priority concern in various sections of the country.

Adolescent↗

PubMed2002

[Expression of TPO mimetic peptide chimeric proteins with human IgG1 Fc fragments and their biological characters].

Many antineoplastic agents can cause myelosuppression and thrombocytopenia. Thrombopoietin (TPO) is believed to be the major cytokine affecting the proliferation and maturation of megakaryocytes and increasing circulating platelet levels. We have designed and synthesized a TPO mimetic peptide, it can increase circulating platelet levels in vivo. For increasing half-life and forming dimer, the peptide was expressed as chimeric proteins with human IgG1 Fc fragments. The cDNA of TPO mimetic peptide was synthesized chemically and linked respectively to 5' terminus of human IgG1 Fc cDNA fragments in various length (Fc1: Fc 5' 648 bp; Fc2: Fc 5' 270 bp; Fc3: Fc 5' 267 bp; Fc4: Fc 5' 90 bp), and cloned into expression plasmid pET28a (+) for constructing four recombinant plasmids. By transforming the four recombinant plasmids into E. coli. BL21 (DE3) respectively, we got 3 kinds of engineered E. coli which express TPO + Fc chimeric proteins(28 kD TPO + Fc1, 12 kD TPO + Fc2 and 12 kD TPO + Fc3) at high level respectively, the expressed proteins were purified with DEAE-Sepharose FF and S-Sepharose FF column. The bioactivities of the expressed chimeric proteins(TPO + Fc1, TPO + Fc2 and TPO + Fc3), TPO mimetic peptide, and PEG4000 coupled TPO mimetic peptide were evaluated with Ba/F3-mp1 in vitro and with carboplatin-induced thrombocytopenia mice in vivo, the expressed chimeric proteins have higher activity than TPO mimetic peptide both in vitro and in vivo, the EC50 on Ba/F3-mp1 cells were 13, 10, 10, 50, and 25 nmol/L respectively, all of them can increase circulating platelet counts. Their imol/Lunogenicity were valuated in mice, none of them can elicit mice to produce antibodies to TPO mimetic peptide, meanwhile three TPO + Fc chimeric proteins can elicit mice to produce antibodies to human IgG1 Fc. These studies have laid basis for production of TPO mimetic peptide by genetic engineering.

Animals↗

PubMed2002

[Screening of TNF-alpha antagonist peptides from a random peptide library displayed with Escherichia coli flagellar].

Tumor necrosis factor(TNF-alpha) plays an improtant role in the process of anti-infection and anti-cancer. It can both protect and make damage to the host. In order to find new way of inhibiting its host-damaging activity, An E. coli flagella displayed random peptide library was constructed and TNF-alpha antagonist peptides were screened using the peptide library. After 5 rounds of panning and DNA sequencing, six peptide sequences were obtained. Two of them(TBP2, TBP3) have the same sequence frame of V--N-WG. After primary comparation of TNF-alpha binding ability, four peptides were synthesised and purified with RP-HPLC. The activity of inhibiting TNF-alpha was detected with L929 cell and MTT method. The data show that TBP2 and TBP3 can inhibit 90% of TNF-alpha activity when TNF-alpha gives about 30% cell toxicity on L929. The two sequences have not been reported.

Escherichia coli↗

PubMedDate not supplied

Long-term viability and mechanical behavior following laser cartilage reshaping.

OBJECTIVE: To investigate the long-term in vivo effect of laser dosimetry on rabbit septal cartilage integrity, viability, and mechanical behavior. METHODS: Nasal septal cartilage specimens (control and irradiated pairs) were harvested from 18 rabbits. Specimens were mechanically deformed and irradiated with an Nd:YAG laser across a broad dosimetry range (4-8 W and 6-16 seconds). Treated specimens and controls were autologously implanted into a subperichondrial auricular pocket. Specimens were harvested an average +/- SD of 208 +/- 35 days later. Tissue integrity, histology, chondrocyte viability, and mechanical property evaluations were performed. Tissue damage results were compared with Monte Carlo simulation models. RESULTS: All laser-irradiated specimens demonstrated variable tissue resorption and calcification, which increased with increased dosimetry. Elastic moduli of the specimens were significantly either lower or higher than controls (all P<.05). Viability assays illustrated a total loss of viable chondrocytes within the laser-irradiated zones in all treated specimens. Histologic examination confirmed these findings. Experimental results were consistent with damage profiles determined using numerical simulations. CONCLUSION: The loss of structural integrity and chondrocyte viability observed across a broad dosimetry range underscores the importance of spatially selective heating methods prior to initiating application in human subjects.

Animals↗