Search PubMed⌕ Search

Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 145 records · Page 8Linked to original sources

Construction and expression of eukaryotic expressing vector pCH510 of polypeptide CH50 and its chemotaxis and antitumor function by in vivo transfection.

To construct an eukaryotic expressing vector that expresses CH50, a recombinant Cell I-Hep II bifunctional-domain polypeptide of human fibronectin, and to investigate the chemotaxis to immune cells and the inhibitory effect on the growth of tumor by the expression of the plasmid in vivo, the plasmid was constructed by DNA recombination. Gene transfection was performed in vitro and in vivo. The expressed product was identified by Western blot. The chemotaxis after gene transfection in vivo was observed by histotomy and staining of muscle tissues. The inhibition of gene transfection on solid tumor was observed in mice. The results showed that plasmid pCH510 was constructed by the recombination of the 5'-terminal noncoding region and signal peptide coding region of human fibronectin cDNA and cDNA fragment coding CH50 polypeptide with a 3'-terminal noncoding region of human FN cDNA, and the insertion of the recombinated fragment into plasmid pcDNA3. 1. After transfection with plasmid pCH510, NIH3T3 cells could produce CH50 polypeptide. The transfection of plasmid pCH510 by the injection in muscle of mouse could produce the effects of chemotaxis on immune cells and the inhibition on the growth of solid tumor. It is concluded that plasmid pCH510 can express in cells and in vivo in mouse. The expression of the plasmid in vivo has a chemotactic effect on immune cells and can inhibit the growth of solid tumor.

3T3 Cells↗

WD-repeat proteins: structure characteristics, biological function, and their involvement in human diseases.

Defined by the presence of four or more repeating units containing a conserved core of approximately 40 amino acids that usually ending with tryptophan-aspartic acid (WD), WD-repeat proteins belong to a large and fast-expanding conservative protein family. As demonstrated by the crystal structure of the G protein beta subunit, all WD-repeat proteins are speculated to form a circularized beta propeller structure. The importance of these proteins is not only demonstrated by their critical roles in many essential biological functions ranging from signal transduction, transcription regulation, to apoptosis, but is also recognized by their association with several human diseases. Defining the function of a WD-repeat protein is the current challenge. It is, however, paramount to uncover the function of individual WD-repeat proteins, explore the protein interaction mechanism through WD-repeat domains and, ultimately, understand the complex biological processes and organisms themselves.

Apoptosis↗

Identification of rice black-streaked dwarf fijivirus in maize with rough dwarf disease in China.

Three virus isolates from maize with rough dwarf in different provinces in China were analyzed at the molecular level. When compared to an isolate from diseased rice plants in Hubei Province, all four isolates had identical genomic RNA electrophoretic profiles, which were composed of ten double-stranded (ds) RNAs. Full-length cDNAs of segment 10 (S10) from each of the four isolates were cloned by RT-PCR and the complete sequences were determined. Analysis of the sequences revealed that each consisted of 1801 nucleotides and contained a single open reading frame (ORF) which potentially encoded a protein with 558 amino acids. Further, the sequences showed more than 97.0% and 98.0% identity at nucleotide and amino acid levels, respectively. In addition, their identities to rice black-streaked dwarf virus S10 were significantly higher than those to maize rough dwarf virus S10. Based on these results, it is suggested that the virus which causes this maize disease in China is rice black-streaked dwarf virus.

China↗

Do adolescent vitamin-mineral supplement users have better nutrient intakes than nonusers? Observations from the CATCH tracking study.

OBJECTIVE: Describe whether users of vitamin-mineral supplements differed from nonusers in micronutrient intakes or in nutrition awareness. DESIGN: Cross-sectional, observational study. SUBJECTS: One thousand five hundred thirty-two students now in grade 8, who participated in the Third Child and Adolescent Trial for Cardiovascular Health tracking study and who also provided a single 24-hour dietary recall. STATISTICAL ANALYSES PERFORMED: Mixed-model analysis of covariance was used to ascertain if supplement users had higher vitamin and mineral intakes from food sources, and to examine if supplement users had better nutrition awareness than nonusers. RESULTS: The 24-hour recall showed that 17.6% of the students reported using vitamin-mineral supplements. Users reported a mean of 1.4 supplements, of which 47% were multivitamin or multimineral preparations, 37% were single nutrients, and 16% were combinations. White persons and residents of Minnesota and California were more likely to be supplement users. Users had higher micronutrient intakes from food sources for 16 of the 20 nutrients studied after adjusting for gender, race/ethnicity, site, treatment condition, and within-school variability. Users had higher scores on a health behavior survey for food choice and slightly but not significantly higher nutrition knowledge scores. CONCLUSIONS: Vitamin-mineral supplement use is prevalent among eighth-grade students. Users have higher nutrient intakes from foods, higher total intakes for several micronutrients, higher nutrition awareness, and differ in their demographic characteristics from nonusers.

Adolescent↗

Remodeling of atrial dimensions and emptying function in canine models of atrial fibrillation.

OBJECTIVES: Atrial tachycardia-induced remodeling (ATR) and ventricular tachypacing-induced heart failure (HF) create experimental substrates for atrial fibrillation (AF), and both have been reported to produce atrial dilation and hypocontractility. The relative importance of changes in atrial size and contractility in the two models is unknown. This study compared changes in atrial dimensions and emptying in ATR versus HF dog models and related them to AF promotion. METHODS: In ATR dogs (n=11), the right atrium (RA) was paced at 400/min for 42 days. In HF dogs (n=10), the right ventricle was paced at 240 bpm for 2 weeks, followed by 3 weeks at 220 bpm. Transthoracic echocardiography was performed at baseline and weekly thereafter. At a terminal electrophysiological study, RA effective refractory period (ERP) was recorded and AF induced repeatedly by atrial burst pacing to measure mean AF duration (DAF). RESULTS: Left atrial (LA) systolic area increased by 10.0% in ATR versus 48.2% in HF dogs (P=0.008), with significant time-dependent changes in HF (P=0.0001), but not ATR (P=0.16). LA diastolic area increased over time in both groups (P=0.004, 0.0001 for ATR and HF respectively), but increases were much larger in CHF (80.2%) compared to ATR (24.2%, P=0.0002). Similar findings were obtained for RA. Fractional area shortening (FAS) decreased by 19.4% (ATR) versus 41.8% (HF, P=0.007) in LA and 13.7% (ATR) versus 33.7% (HF, P=0.03) in RA. RA ERP correlated with DAF in ATR dogs (r=-0.79, P<0.001), but not in HF dogs (r=0.20, P=NS). DAF and diastolic areas of RA and LA were highly correlated (r=0.71, 0.77; P<0.01 for each) in HF dogs, but not in ATR dogs (r=-0.18, 0.29; P=NS). CONCLUSIONS: Remodeling of atrial size and emptying function is much greater in HF than in ATR. Whereas in ATR, electrophysiological remodeling is of prime importance in AF promotion, structural remodeling (as reflected in changes in atrial size and contraction) appears much more important in HF-induced AF.

Animals↗

AFP-L3: a new generation of tumor marker for hepatocellular carcinoma.

BACKGROUND: Alpha-fetoprotein (AFP) from hepatocellular carcinoma (HCC) displays differential affinity to lectin Lens culinaris agglutinin (LCA) compared to that from chronic hepatitis/liver cirrhosis. According to their binding capability to LCA, total AFP can be separated into three different glycoforms, AFP-L1, AFP-L2, and AFP-L3. AFP-L1 is the non-LCA-bound fraction, which constitutes the major glycoform of AFP in serum of chronic hepatitis and liver cirrhosis. AFP-L3 is the LCA-bound fraction of AFP. It has been reported that malignant liver cells produce AFP-L3, even when HCC is at its early stages, and especially when the tumor mass is supplied by the hepatic artery. Clinical research has determined that AFP-L3 is a highly specific marker for HCC. The AFP-L3 can be detected in the serum of approximately 35% of the patients with small HCC (<2 cm). The AFP-L3-positive HCC has potential for rapid growth and early metastasis. Compared to imaging techniques, it has been shown to have 9-12 months of lead-time in early HCC recognition. Combined sensitivity of AFP-L3 for HCC is 56%, with a specificity of >95%. METHODS: Automated assay for measuring AFP-L3 has been developed and introduced in clinical use. The new automated method for measurement of ALP-L3 is based on liquid phase binding of the AFP-L3 glycoform with LCA and two specific monoclonal antibodies labeled with peroxidase and polysulfated tyrosine peptide, respectively. CONCLUSION: AFP-L3 is a new generation of tumor marker for HCC and yields useful information on HCC for clinical decision making.

Biomarkers, Tumor↗

Sesquiterpene polyol esters from Tripterygium wilfordii.

The extract (T(II)) of Tripterygium wilfordii Hook f. afforded four sesquiterpene esters: 1beta,2beta,5alpha,8beta,11-pentaacetoxy-4alpha-hydroxy-3alpha(2'-methylbutanoyl)-15-nicotinoyl-7-oxo-dihydroagarofuran; 1beta,5alpha,11-triacetoxy-7beta-benzoyl-4alpha-hydroxy-8beta-nicotinoyl-dihydroagarofuran; 1beta,2beta,5alpha,11-tetraacetoxy-8alpha-benzoyl-4alpha-hydroxy-7beta-nicotinoyl-dihydroagarofuran; 5alpha-benzoyl-4alpha-hydroxy-1beta,8alpha-dinicotinoyl-dihydro- agarofuran as well as one other known sesquiterpene ester. Their structures were established on the basis of spectroscopic studies.

Circular Dichroism↗

Study on the kinetics of cerium(III) adsorption-desorption on different soils of China.

The kinetics of Ce(III) adsorption-desorption on four typical soils in China has been studied by using the batch method with the radioactive nuclide 141Ce. Results indicated that Ce(III) adsorption was rapid and nearly finished in less than 0.5 min. Desorption procedure was about completed in 1-30 min in the tested soils. Ce(III) desorption equilibrium times vary with different soils. The amounts of Ce(III) desorption on different soils in the same time were different. The Elovich equation proved to be the best models for fitting the data of Ce(III) desorption reactions in fluvo-aquic soil and black soil; and the parabolic-diffusion equation was the best model in red earth and loess soil.

Adsorption↗

Determination of surface free energy of interactive dry powder liposome formulations using capillary penetration technique.

The surface free energy of interactive dry powder formulations consisting of varying ratios of lactose plus liposomal ciprofloxacin were determined using capillary penetration technique. Powder is produced by jet-milling after mixing with lyophilized liposomal ciprofloxacin with inhalation grade lactose powder (Pharmatose 325M). Measurement of the weight gained during intrusion of different liquids in a packed column of powder is combined with dynamic considerations to give the surface free energy, gamma(sv). Confidence in methodology was gained by determining gamma(sv) for PMMA microspheres and comparing to literature values. Values of gamma(sv) are then obtained for unmilled Pharmatose 325M powder (gamma(sv)=54.2 mJ m(-2)), milled Pharmatose 325M (gamma(sv)=54.2 mJ m(-2)) and lipid:lactose formulations with weight ratios of 1:5, 1:10 and 1:20. All the powder liposomal formulations are found to have the same gamma(sv)=48.0 mJ m(-2), suggesting that adhesive forces in the three interactive powders should be similar barring any confounding roughness effects.

Journal Article↗

Simulation of biomass gasification with a hybrid neural network model.

Gasification of several types of biomass has been conducted in a fluidized bed gasifier at atmospheric pressure with steam as the fluidizing medium. In order to obtain the gasification profiles for each type of biomass, an artificial neural network model has been developed to simulate this gasification processes. Model-predicted gas production rates in this biomass gasification processes were consistent with the experimental data. Therefore, the gasification profiles generated by neural networks are considered to have properly reflected the real gasification process of a biomass. Gasification profiles identified by neural network suggest that gasification behavior of arboreal types of biomass is significantly different from that of herbaceous ones.

Biomass↗

Immunosuppressive sesquiterpene alkaloids from Tripterygium wilfordii.

Nine new sesquiterpene pyridine alkaloids [wilfornines A (1), B (2), C (3), D (4), E (5), F (8), and G (9); wilfordinines I (6) and J (7)] and six known compounds (10-15) were isolated from a clinically used extract (T(II)) of Tripterygium wilfordii. The structures of 1-9 were elucidated by spectroscopic and chemical methods. The inhibitory effects on cytokine production of 1-3 and several related compounds were evaluated. Compounds 10 and 14 showed significant inhibitory effects on cytokine production.

Alkaloids↗

Mdr1 transfection causes enhanced apoptosis by paclitaxel: an effect independent of drug efflux function of P-glycoprotein.

PURPOSE: We previously reported that in patient tumors the expression of the mdrl p-glycoprotein (Pgp) resulted in a lower paclitaxel-induced inhibition of DNA precursor incorporation, but a higher apoptosis (Clin. Cancer Res. 4:2949-2955, 1998). The present study was to evaluate these findings in an experimental system where the Pgp effect can be studied without confounding factors such as the intra- and inter-tumor heterogeneity associated with patient tumors. METHODS: To separate the effect of Pgp on intracellular paclitaxel accumulation from its effects on drug sensitivity, we compared the drug activity at various extracellular and intracellular drug concentrations using the human breast MCF7 tumor cells and its mdr1-transfected variant BC19 cells. RESULTS: Compared to MCF7 cells, BC19 cells showed a 9-fold higher Pgp level and >13-fold higher mdrl expression. Intracellular paclitaxel accumulation was 80-130% lower in BC19 cells when the extracellular concentrations were < or = 100 nM, but the difference was reduced to <15% differences at higher extracellular concentrations of > or = 1,000 nM. For the G2/M block effect MCF7 cells were 43-fold more sensitive than BC19 cells at equal extracellular concentration, and 3.5-fold more sensitive at comparable intracellular concentrations. On the contrary. BC19 cells were more sensitive to the apoptotic effect: BC19 cells showed equal or higher apoptosis compared to MCF7 cells at extracellular concentrations above 100 nM, and a 30-100% higher apoptosis at comparable intracellular concentrations. CONCLUSIONS: These results confirm our previous observations in patient tumors and indicate that enhanced Pgp expression is associated with enhanced sensitivity to the apoptotic effect of paclitaxel and reduced sensitivity to its G2/M block effect, via yet-unknown mechanisms that are unrelated to the effect of Pgp on intracellular drug accumulation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

High prevalence of Mycoplasma pneumoniae in intestinal mucosal biopsies from patients with inflammatory bowel disease and controls.

Intestinal microflora are believed to play an important role in the pathogenesis of inflammatory bowel disease (IBD). Mycoplasma have been suggested previously as organisms of ubiquitous distribution with the potential to cause inflammatory diseases, including IBD in susceptible individuals. The aim of this study was to determine the frequency of the presence of M. pneumoniae DNA in intestinal biopsies from patients with IBD and non-IBD controls using a microplate polymerase chain reaction-hybridization assay (PCR-ELISA). A total of 260 endoscopic biopsies (49 from 19 patients with Crohn's disease, 76 from 27 patients with ulcerative colitis, and 135 from 43 non-IBD controls) were used in this study. Overall, M. pneumoniae-specific DNA was detected in 100 endoscopic biopsy samples (38.5%). Among them, the detection rate of M. pneumoniae DNA was significantly higher in biopsies from patients with CD (59.2%) than in those from patients with UC (26.3%) or non-IBD controls (37.7%) (chi2 = 13.65, P < or = 0.001). The high prevalence of M. pneumoniae in both IBD patients and controls suggest this organism is ubiquitous and may persist in the intestinal mucosa. Epidemiological studies in IBD suggest acquisition of some agents early in life probably during epidemics in temperate latitudes. M. pneumoniae could be one of the ubiquitous agents implicated in the pathogenesis of IBD.

Adult↗

The alpha-linolenic acid content of green vegetables commonly available in Australia.

Green vegetable consumption has long been considered to have health benefits mainly due to the vitamins, minerals and phytonutrients (such as vitamin C, folate, antioxidants etc) contained in a vegetable-rich diet. Additionally, green vegetables are known to contain a relatively high proportion of omega-3 polyunsaturated fatty acids (PUFAs), primarily in the form of alpha-linolenic acid (18:3n-3). However, there are no data available on the fatty acid composition and concentration of green vegetables commonly consumed in Australia. The present study determined the fatty acid content of 11 green vegetables that are commonly available in Australia. The total fatty acid concentrations of the vegetables under study ranged from 44 mg/100 g wet weight in Chinese cabbage to 372 mg/100 g in watercress. There were three PUFAs in all vegetables analyzed; these were 16:3n-3, 18:2n-6, and 18:3n-3 fatty acids. Sample vegetables contained significant quantities of 16:3n-3 and 18:3n-3, ranging from 23 to 225 mg/100 g. Watercress and mint contained the highest amounts of 16:3n-3 and 18:3n-3, and parsley had the highest amount of 18:2n-6 in both percentage composition and concentration. Mint had the highest concentration of 18:3n-3 with a value of 195 mg/100 g, while watercress contained the highest concentration of 16:3n-3 at 45 mg/100 g. All 11 green vegetables contained a high proportion of PUFAs, ranging from 59 to 72% of total fatty acids. The omega-3 PUFA composition ranged from 40 to 62% of total fatty acids. Monounsaturated fatty acid composition was less than 6% of total fatty acids. The proportion of saturated fatty acids ranged from 21% in watercress and mint to 32% of total fatty acids in Brussels sprouts. No eicosapentaenoic and docosahexaenoic acids were detected in any of the samples. Consumption of green vegetables could contribute to 18:3n-3 PUFA intake, especially for vegetarian populations.

Australia↗

ErbB2, but not ErbB1, reinitiates proliferation and induces luminal repopulation in epithelial acini.

Both ErbB1 and ErbB2 are overexpressed or amplified in breast tumours. To examine the effects of activating ErbB receptors in a context that mimics polarized epithelial cells in vivo, we activated ErbB1 and ErbB2 homodimers in preformed, growth-arrested mammary acini cultured in three-dimensional basement membrane gels. Activation of ErbB2, but not that of ErbB1, led to a reinitiation of cell proliferation and altered the properties of mammary acinar structures. These altered structures share several properties with early-stage tumours, including a loss of proliferative suppression, an absence of lumen, retention of the basement membrane and a lack of invasive properties. ErbB2 activation also disrupted tight junctions and the cell polarity of polarized epithelia, whereas ErbB1 activation did not have any effect. Our results indicate that ErbB receptors differ in their ability to induce early stages of mammary carcinogenesis in vitro and this three-dimensional model system can reveal biological activities of oncogenes that cannot be examined in vitro in standard transformation assays.

Animals↗

The occurrence of trans-18:1 isomers in plasma lipids classes in humans.

OBJECTIVE: The aim of this study was to examine the distribution of trans fatty acids (TFA) in plasma lipid classes and the relationship with dietary intake of TFA. DESIGN: After a 2 week baseline (habitual) diet, all subjects consumed a moderate fat (MF) diet for 3 weeks with the fat being derived mainly from margarine and the rest from lean beef, and then a very low fat (VLF) diet for 3 weeks with the TFA being derived only from the lean beef. Blood samples were collected 2 days prior to the end and also on the last day of each dietary period. SETTING: Deakin Institute of Human Nutrition, Deakin University, Geelong, Australia. SUBJECTS: Ten free-living mildly hypercholesterolaemic subjects aged 22-66 were recruited in Geelong. OUTCOME MEASURES: TFA intake was calculated from analyses of Australian margarines, butter, lean meat and animal fat. The TFA in plasma lipid fractions were separated by AgNO3 thin-layer chromatography and quantitated by capillary gas-liquid chromatography using internal standards. RESULTS: The phospholipid (PL) fraction contained more than 60% of the trans-18:1 isomers in the plasma lipids in all subjects. On the baseline diet, the predominant positional isomer of trans-18:1 in PL was delta11, whereas in the other lipid classes it was the delta9 isomer. The concentration of the delta9 isomer increased on the MF diet, particularly in the PL fraction, while the concentration of the delta11 isomer decreased in all fractions. On the VLF diet, the total TFA level decreased by approximately 50%, mainly due to decreases in the TFA isomers in the PL and TG fractions. Changes in plasma total and PL TFA, PL delta9, delta10 and delta11 were strongly correlated with dietary TFA intake (P < 0.0001). There were also significant association between dietary TFA intake and PL delta12 (P = 0.003), triacylglycerol delta9 (P=0.009), delta11 (P=0.0005), total triacylglycerol (P=0.023) and free fatty acid TFA (P = 0.042). CONCLUSIONS: The results suggest that the measurement of trans-18:1 in plasma PL and TAG, and plasma total TFA could be used to estimate the intake of TFA.

Adult↗

A stearic acid-rich diet improves thrombogenic and atherogenic risk factor profiles in healthy males.

OBJECTIVE: To determine whether healthy males who consumed increased amounts of dietary stearic acid compared with increased dietary palmitic acid exhibited any changes in their platelet aggregability, platelet fatty acid profiles, platelet morphology, or haemostatic factors. DESIGN: A randomized cross-over dietary intervention. SUBJECTS AND INTERVENTIONS: Thirteen free-living healthy males consumed two experimental diets for 4 weeks with a 7 week washout between the two dietary periods. The diets consisted of approximately 30% of energy as fat (66% of which was the treatment fat) providing approximately 6.6% of energy as stearic acid (diet S) or approximately 7.8% of energy as palmitic acid (diet P). On days 0 and 28 of each dietary period, blood samples were collected and anthropometric and physiological measurements were recorded. RESULTS: Stearic acid was increased significantly in platelet phospholipids on diet S (by 22%), while on diet P palmitic acid levels in platelet phospholipids also increased significantly (8%). Mean platelet volume, coagulation factor FVII activity and plasma lipid concentrations were significantly decreased on diet S, while platelet aggregation was significantly increased on diet P. CONCLUSION: Results from this study indicate that stearic acid (19g/day) in the diet has beneficial effects on thrombogenic and atherogenic risk factors in males. The food industry might wish to consider the enrichment of foods with stearic acid in place of palmitic acid and trans fatty acids.

Adult↗