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Biomedical subjects

Hui Li

Publications and source records attributed to Hui Li.

394 records · Page 22Linked to original sources
PubMed1999

Osteogenic potential of rabbit dermal fibroblasts cultured in vitro: a scanning electron microscopic study.

OBJECTIVE: To investigate further into the osteogenic potential of rabbit dermal fibroblasts with scanning electron microscope. METHODS: Split-thickness rabbit skin was processed into small chips that were cultured in vitro and then subjected to scanning electron microscopic study. RESULTS: The fibroblasts swam out from the skin chips and they increased in number rapidly and became confluent. The cells exhibited squamous configuration, possessing arboreal bifurcation and forming multi-layer structure. The fibroblasts then excreted numerous minute granules, heaping up on and around the cells. Thenceforth emerged on the cell surface fine needle-like crystals, that agglomerated with the granules to form nodules. The fibroblasts orientated themselves in a radiating pattern around the large nodules. Neighboring nodules could be linked up into trabecular structures. CONCLUSIONS: Sequence of events of new bone formation by rabbit dermal fibroblasts cultured in vitro is fully depicted and confirmed.

Journal Article↗
PubMed1999

Long-term effectiveness of infancy low-dose hepatitis B vaccine immunization in Zhuang minority area in China.

AIM:To observe the long-term effectiveness of low-dose immunization strategy and risk factors of HBsAg carriers in immunized children of Zhuang minorities of Longan County in the 9th year after infancy immunization.METHODS:Two epidemiologic methods,a cross-sectional follow-up study and a case-control study,were used for the evaluation of the serological effect and the determination of the risk factors. Hepatitis B virus markers were detected with radioimmunoassay.RESULTS:The protective anti-HBs-positive rate was 43.8% in 1183 children aged 1-9 years,who were immunized with three doses of 10&mgr;g hepatitis B vaccine in infancy according to 0, 1 and 6 months schedul.It declined from 87.9% in the first year to 37.1% in the 9th year after vaccination.The HbsAg-positive rate was 1.6%, not increasing with age during 9 years after the infant immunization program. Compared with 14.0% of HbsAg-positive rate of the baseline survey in 1985, the effectiveness of hepatitis B vaccine immunization was 88.6%. Of 36 immunized children with positive HBsAg, 89.1% were likely attributable to HBsAg positivity of their mothers.CONCLUSION:The long-term effectiveness of infancy low-dose hepatitis B vaccine immunization is high,and the booster is not needed 9 years after the vaccination in the Zhuang minority area where hepatitis B is highly endemic.A high-dose immunization strategy should be recommended in order to further decrease the current HbsAg-positive rate.

Journal Article↗
PubMed1999

Survey of coverage, strategy and cost of hepatitis B vaccination in rural and urban areas of China.

AIM:In order to understand the coverage, immunization strategy and cost of hepatitis B (HB) vaccination of China in recent years.METHODS:A two-stage household random sampling method was used in the survey.RESULTS:The survey carried out at 112 Disease Surveillance Points (DSPs) of 25 provinces, autonomous regions and municipalities of China in 1996, showed that the coverage rates of HB vaccination among neonates were 96.9% in the urban DSPs and 50.8% in the rural DSPs in 1993-1994,while in students aged 7-9 years, they were 85.8% and 31.5% in 1994, respective-ly. Up to 1994, 97.5% of the urban DSPs and 73.9% of the rural DSPs on a neonate vaccination against HB program were included in EPI. About 93% of the urban DSPs and 44% of the rural DSPs did HBsAg and HBeAg screening for all or part of pregnant women. The neonates received the regimen of high-dose HB vaccine in combination with hepatitis B immune globin (HBIG) if their mothers were HBsAg and/or HBeAg positive in pregnancy,otherwise they received the low-dose vaccine (10&mgr;gX3). Part of DSPs had a lower neonate coverage due to unreasonable allocation of the vaccines (used for adults not at risk) or higher cost or insufficient supply of the vaccines. It is necessary to evaluate the quality of serological lab test to HBVMs in the maternal prescreening.CONCLUSION:Remarkable achievements have been made according to the national planning and policy of HB immunization in China.

Journal Article↗
PubMed1998

Ultrastructural investigation of traumatic avascular necrosis of femoral-head.

OBJECTIVE: To investigate ultrastructurally into traumatic avascular necrosis of femoral head. METHODS: Femoral heads were procured during endoprosthetic replacement for 8 cases of intracapsular fracture of femoral neck, which had been subjected to internal fixation and developed Stage II avascular necrosis. The specimens were processed and studied under transmission electron microscope. RESULTS: In the normal bone tissues of the avascular necrotic femoral heads, the collagen fibrils constituting the collagen bundles of the bone matrix were of uniform diameter, and were regularly arrayed with orientation. In the necrotic bone tissues of the avascular femoral heads, the collagen fibrils were of unequal diameter, and were haphazardly arrayed without orientation. From the trabeculae of the avascular femoral heads emerged three different conditions of osteocytes: (1) In the trabeculae of normal bone tissues, the osteocytes belonged to both degenerative phase and formative phase osteocytes with the latter showing signs of degeneration; (2) In the necrotic trabeculae, the osteocytes perished leaving behind empty lacunae; (3) Over the trabeculae of the interface region could be discerned many active osteogenic cells, which were on their way of transformation into osteoblasts. In the trabeculae here, the osteocytes belonged to both formative phase and degenerative phase osteocytes. CONCLUSIONS: These results suggest that in the femoral heads with traumatic avascular necrosis, there is active osteogenetic activity around the necrotic bone tissues, amply implying a local reparative response following partial bone necrosis.

Journal Article↗
PubMed1998

Persistence of hepatitis B vaccine immune protection and response to hepatitis B booster immunization.

AIM:To identify the persistence of immune protection of China-made, plasma derived hepatitis B vaccine after infancy immunization and the time table of booster immunization.METHODS:A cross-sectional follow-up study and an experimental study on booster were used for the evaluation of the serological effect 7 years after vaccination and the antibody anamnestic response. Radioimmunoassay was used for the detection of hepatitis B virus markers. RESULTS:The protective anti-HBs positive rates of 1018 children, who were vaccinated according to the regimen of three doses of 10 &mgr;g hepatitis B vaccine in their infancy, declined from 75.0% during the first two years to 48.2% in the 7th year after the first dosage, however, the positive rates for HBsAg and anti-HBc always fluctuated at a low frequency. A total of 144 subjects aged 6 or 7 years, who were negative for both HBsAg and anti-HBc before booster, were selected from 1018 children of the follow-up study, and boosted with 1&mgr;g intradermally or 2&mgr;g hypodermically hepatitis B vaccines. Their anti-HBs GMT and anti-HBs positive rates were 190.6mIU/ml and 89.6% in the first month after booster,significantly higher than 14.7mIU/ml and 54.9% before booster (P < 0.01), and declined back to 25.3mIU/ml and 75.5% in the 12th month; among 65 children with the anti-HBs negative before booster, 40 had a level of anti-HBS< = 100mIU/ml one month after booster, suggesting retention of immune memory in most of them.CONCLUSION:No need for revaccination against hepatitis B in the 7th year after the initial immunization due to better persistence of immune protection of the vaccine and retention of immune memory to hepatitis B virus in the vast majority of the vaccinees.

Journal Article↗
PubMedDate not supplied

Effects of ethanol on embryonic and neonatal rat testes in organ cultures.

Ethanol exposure in adult animals and humans has shown to elicit significant inhibitory effects on the function of male reproduction, but consequences of ethanol exposure on the embryonic and early postnatal testis development are not known. The current study investigated the effect of ethanol on embryonic and neonatal testis development using an organ culture technique. In embryonic day 13 (E13) testis organ cultures, ethanol had no effect on the testicular cord formation, the expression of Müllerian-inhibiting substance (MIS) in Sertoli cells or the number of gonocytes. Similarly, in the ethanol-treated embryonic day 18 (E18) testes, both the number of gonocytes and the expression of GATA-4 and MIS were similar to those from the control testes. In contrast, in postnatal day 3 (P3) testes, ethanol at concentrations of 150 and 200 mM significantly decreased the number of gonocytes without affecting the expression of GATA-4 and MIS in Sertoli cells. This effect was shown to be resulting from the enhanced apoptosis of gonocytes. In addition, ethanol abnormally activated retinoic acid receptor alpha (RARalpha), as indicated by increased nuclear localization of RARalpha with increasing doses of ethanol treatment. These observations suggest that the effect of ethanol on testis varies at different stages during embryonic and neonatal testis development. Furthermore, germ cells may be the main target for the action of ethanol on the early postnatal testis.

Animals↗
PubMedDate not supplied

Solvent effects on focused microwave assisted extraction of polyphenolic acids from Eucommia ulmodies.

An open microwave-assisted extraction system was used to extract gallic acid, protocatechuic acid, chlorogenic acid and caffeic acid from Eucommia ulmodies. The effect of extraction variables, especially solvent, on the recoveries of these polyphenolic compounds was investigated using factorial design. As extracting solvent for these compounds, methanol produced a higher recovery than pure water. For straight chain alcohol solvents, the lower the carbon number, the higher the recoveries of the polyphenolic acids. The optimal ratio of methanol:water:glacial acetic acid in the solvent mixture used in microwave-assisted extraction was 2:8:0.3 (v/v) and this solvent could be directly used as the mobile phase in HPLC separation without additional intermittent treatment as reported in literature. The extraction under the condition of 50% microwave power and 30 s irradiation at a solvent:sample ratio of 10 (mL/g) was found to be the most advantageous. The repeatability test of extraction and chromatographic analysis was satisfactory for the analysis of these polyphenolic compounds.

Chemistry Techniques, Analytical↗
PubMedDate not supplied

Low-density lipoprotein reconstituted by pyropheophorbide cholesteryl oleate as target-specific photosensitizer.

To target tumors overexpressing low-density lipoprotein receptors (LDLr), a pyropheophorbide cholesterol oleate conjugate was synthesized and successfully reconstituted into the low-density lipoprotein (LDL) lipid core. Laser scanning confocal microscopy studies demonstrated that this photosensitizer-reconstituted LDL can be internalized via LDLr by human hepatoblastoma G(2) (HepG(2)) tumor cells.

Binding, Competitive↗
PubMedDate not supplied

Pyropheophorbide 2-deoxyglucosamide: a new photosensitizer targeting glucose transporters.

To prepare near-infrared fluorescence imaging and photodynamic therapy agents targeted at glucose transporters, pyropheophorbide 2-deoxyglucosamide (Pyro-2DG) was synthesized and evaluated in a 9L glioma rat model. Fluorescence imaging studies demonstrate that Pyro-2DG is selectively accumulated in the tumor. Upon its photoactivation, we demonstrate that this agent efficiently causes selective mitochondrial damage to the region of a tumor that was photoirradiated after administration of this agent, but does not affect tissues photoirradiated in the absence of the agent or tissues treated with the agent that are not photoirradiated. Preliminary confocal microscopy studies suggest that Pyro-2DG is delivered and trapped in tumor cells via the GLUT/hexokinase pathway and therefore is useful both as a tumor-targeted NIR fluorescence imaging probe and as a PDT agent for the destruction of cancer.

Animals↗
PubMedDate not supplied

Possible participation of pICln in the regulation of angiogenesis through alternative splicing of vascular endothelial growth factor receptor mRNAs.

In this study, the authors applied a modified Antisense Display method to human vascular endothelial cells (ECs) in culture to isolate new angiostatic genes. Screening of a 10mer antisense oligodeoxyribonucleotide (oligo) repertoire identified a subpool that consistently stimulated EC growth. Subsequent screening of oligos with increasing chain length led to the isolation of a unique growth-stimulatory 14mer, 5'-TTCCACATCATATT-3'. cDNA/EST data-base search and expression analyses in ECs indicated pICln as the corresponding gene. A longer unique antisense oligo against a different region of pICln mRNA was found to also enhance EC growth and tube formation and to decrease mRNAs for soluble Flt-1 and neuropilin-1 vascular endothelial growth factor (VEGF) receptors, the angiostatic factors that are generated by alternative RNA splicing. Conversely,pICln overexpression suppressed EC growth and increased the mRNAs for both soluble Flt-1 and soluble neuropilin-1. The present findings thus suggest that pICln plays a role in autocrine regulation of angiogenesis, probably through alternative splicing.

Alternative Splicing↗
PubMedDate not supplied

Pancreatic adenocarcinoma: the different CT criteria for peripancreatic major arterial and venous invasion.

OBJECTIVE: To establish preliminarily the different diagnostic criteria for peripancreatic arterial and venous invasion in pancreatic carcinoma by comparing their multidetector-row computed tomography (MDCT) appearances with surgical exploration. METHODS: Among 101 patients with pancreatic carcinoma examined by MDCT, 54 candidates accepting surgery were preoperatively evaluated for vascular invasion based on CT signs (A-E): arterial embedment in tumor or venous obliteration; tumor involvement exceeding one-half of the circumference of the vessel; vessel wall irregularity; vessel caliber stenosis; teardrop superior mesenteric vein (SMV). The peripancreatic major vessels (n = 224) were examined carefully by surgeons during the operation. RESULTS: During surgical exploration, 78 vessels were found to be invaded. With sign A (B, C, or D) as the CT criterion for peripancreatic vascular invasion, the sensitivity of arterial and venous invasion was 66% (97%, 45%, or 41%) and 14% (49%, 63%, or 55%), respectively; the specificity of absence of arterial and venous invasion was 100% (91%, 99%, or 100%) and 100% (all 100%). In this study, there were 3 SMVs appearing teardrop (sign E), which were all confirmed to be invaded. CONCLUSIONS: It is recommended that the CT diagnostic criteria for arterial and venous invasion should be dealt with differently. The criteria of arterial invasion are the presence of sign A or the combination of sign B with one of signs C and D. The criteria of venous invasion are the presence of one of the following signs: sign A, sign B, sign C, sign D, and sign E.

Adult↗
PubMedDate not supplied

Redox ratio of mitochondria as an indicator for the response of photodynamic therapy.

The effect of photodynamic therapy (PDT) treatment on the metabolic state of tumor mitochondria is investigated by imaging of tumor redox status. PDT is performed using the photosensitizer pyropheophorbide-2-deoxyglucosamide (Pyro-2DG), which utilizes the glucose import pathway. It is found that Pyro-2DG-induced PDT resulting in a highly oxidized state of tumor mitochondria. This is determined from the redox ratio changes derived from the intrinsic oxidized flavoprotein (Fp) and reduced pyridine nucleotide (PN) [i.e., reduced nicotinamide adenine dinucleotide (NADH)] fluorescence signals observed using a cryoimager. Thus, the redox ratio is a sensitive indicator for providing reliable and informative measurements of PDT-induced tissue damage. In the PDT treated region of the tumor, highly oxidized flavoprotein and diminishing NADH fluorescence is detected, suggesting that flavoprotein and NADH are oxidized by singlet oxygen produced in the photosensitization process.

Animals↗
PubMedDate not supplied

High payload delivery of optical imaging and photodynamic therapy agents to tumors using phthalocyanine-reconstituted low-density lipoprotein nanoparticles.

To improve the labeling efficiency of a low-density lipoprotein (LDL)-based photosensitizer (PS) for achieving high probe to protein payload, a tetra-t-butyl silicon phthalocyanine bearing two oleate moieties at its axial positions, SiPcBOA, is designed and synthesized. Using this novel strategy, SiPcBOA reconstituted LDL (r-SiPcBOA-LDL) with a very high payload (SiPcBOA to LDL molar ratio >3000 to 35001:1) is obtained. Using electron microscopy, we find reconstituted LDL (rLDL) with such a high payload essentially retains the mean particle size of native LDL. Since acetylated LDL binds to scavenger receptors of endothelial and microglial cells instead of LDLR, SiPcBOA reconstituted acetylated LDL (r-SiPcBOA-AcLDL) is also prepared to serve as a negative control to validate the LDL receptor (LDLR) targeting specificity. Confocal microscopy studies demonstrate that the internalization of r-SiPcBOA-LDL by human hepatoblastoma G2 (HepG2) tumor cells is mediated by LDLR pathway. The in vitro photodynamic therapy (PDT) response of HepG2 cells to r-SiPcBOA-LDL is compared to SiPcBOA (free drug control) using a clonogenic assay. The slopes of the linear regression fit to the logarithmic data for these two plots are significantly different from each other (p=0.0007), indicating greatly enhanced efficacy of LDLR-targeted PDT.

Cell Line, Tumor↗
PubMedDate not supplied

Targeted photodynamic therapy agent with a built-in apoptosis sensor for in vivo near-infrared imaging of tumor apoptosis triggered by its photosensitization in situ.

Imaging apoptotic cells or tissues after cancer therapy in situ would be a very useful tool for assessing proper treatment conditions and therapeutic outcome. By combining therapeutic and imaging functions, we have designed a multifunctional, membrane-permeable, and cancer-specific agent that triggers and images apoptosis in targeted cells. We chose photodynamic therapy (PDT) as an appropriate cancer treatment modality and caspase 3 as an apoptosis-specific imaging target. This targeted photodynamic therapy agent with a built-in apoptosis sensor (TaBIAS) induces photodamage only to target cells and simultaneously identifies those that are apoptotic by its near-infrared fluorescence. It contains a fluorescent photosensitizer used as an anticancer drug and a cancer-associated folate receptor homing molecule connected to a caspase 3 cleavable peptide linker that has a fluorescence quencher on the opposing site. We demonstrated that PDT-triggered cleavage of the peptide linker by caspase 3, one of the key executioner caspases, results in a detectable increase in fluorescence in folate receptor-overexpressing cancer cells and tumors. The presence of apoptosis was confirmed in vitro by flow cytometry and ex vivo by Apoptag assay, supporting the ability of TaBIAS to specifically induce and image apoptosis in situ.

Animals↗