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Biomedical subjects

Song Li

Publications and source records attributed to Song Li.

At least 127 records · Page 7Linked to original sources
PubMed2003

[The epidemiology of neural tube defects in high-prevalence and low-prevalence areas of China].

OBJECTIVE: To describe the epidemiology of neural tube defects (NTDs) in high- and low-prevalence areas of China. METHODS: Birth defects surveillance data, collected from 1992 through 1994 was analyzed. These data were collected as part of the Sino-American cooperative project on NTDs prevention. We classified NTDs as anencephaly, encephalocele, high-level and low-level spina bifida (SB) according to location of the lesion (high vs low) and whether the defect was isolated or occurred in association with other birth defects. Rates were compared in the high-prevalence (North) region and the low-prevalence (South) region, after adjusted for classification, urban and rural, season and sex, and calculated the adjusted rate of NTDs. RESULTS: Among seven hundred and eighty-four NTDs cases in 326 874 recorded births (include in livebirth, stillbirth and fetal death with a gestational age of at least 20 weeks), the overall NTDs prevalence in the North was 5.57/1,000 births, and in the South was 0.88/1 000. There were also significant differences in the prevalence of anencephaly, encephalocele, high-level and low-level SB between North (0.97, 0.49, 2.75 and 1.11/1,000 birth) and South (0.36, 0.15, 0.21 and 0.14/1,000 birth) (P < 0.01), with adjusted prevalences in the North 3 - 7 times higher than those in the South. There were significant difference between urban (2.04) and rural areas (6.57/1,000 birth) in the North (P < 0.01), urban (0.52) and rural areas (0.95/1,000 birth) in the South (P < 0.05). Adjusted prevalence rates in the rural were 3 - 4 times higher than those of urban in the North and 1.6 - 1.9 times higher than in the South; The seasonal rate of high-level SB increased between September and November in the North (3.44/1,000 birth), while the seasonal rate of anencephaly decreased between September and November (0.18/1,000 birth) in the South. However there were no seasonal changes in other classified NTDs both in the South and North. CONCLUSIONS: The birth prevalence of NTDs in the North of China was the highest in the world. There were significant differences between the North and the South, urban and rural. There was seasonal change in high-level SB in the North, which was in accordance to the phenotype of NTDs. It was suggested that there might exist etiological heterogeneity among anecephalus, low- and high-level SB.

China↗
PubMed2003

[Detection of the transmitted strains and non-transmitted strains of Mutans streptococci by AP-PCR].

OBJECTIVE: Dental caries is a transmissible infectious disease in which S. mutans plays the major role. The purpose of this study was to detect the S. mutans transmitted strains and non-transmitted strains by AP-PCR fingerprint for laying the foundation of study on the relation between bacterial properties of S. mutans and its transmission. METHODS: Plaque samples were obtained from buccal surfaces of 20 3-4 years old children and their mothers. Caries experience was scored by dmft (DM-FT). Diet regime, breast feeding and care of the children were recorded. 200 Isolates of S. mutans were detected by S. mutans B medium and confirmed biochemically. DNA from each isolate was purified and AP-PCR fingerprinting was conducted. Amplicons were separated by electrophoresis in 1.5% agarose gels. RESULTS: 45 different patterns among the 200 isolates were found. There were 10 mothers (50%) and 15(75%) children owning one genotype while 10 mothers and 5 children owning more than one (2 mothers owning 5 types). The data showed that the mothers harbored a more heterogeneous population of S. mutans than their children. Comparisons in genotypes between children and their mothers discovered that 16(80%) children harbored the same genotypes as their mothers, indicating high transmission in the group of people. Detection of the S. mutans transmitted strains and non-transmitted strains in mothers demonstrated that 10 (50%) mothers harbored not only transmitted strains but also non-transmitted strains, suggesting that different strains had different ability of transmission. CONCLUSION: AP-PCR was capable of detecting the S. mutans transmitted strains and non-transmitted strains. Some S. mutans genotypes had higher ability of transmission than others.

Child, Preschool↗
PubMed2003

[Effects of tobacco on proliferation and attachment of human periodontal ligament fibroblast].

OBJECTIVE: To evaluate the effects of nicotine and tobacco extract (ST) on PDLFs morphology, structure, proliferation and attachment. METHODS: PDLFs were cultured in the presence of nicotine and ST at various concentration. The cell changes in the morphology and structure were examined by histological and transmission electrical microscope (TEM). The growth and attachment of cell were measured by MTT method. RESULTS: The size of the cells became smaller gradually and their shapes changed from shuttle type to oval or round when the concentration of nicotine and ST increased, the polarity of the cells was in disorder, ultrastructure showed that the organelles, especially rough-surfaced endoplasmic reticulum and golgi complex decreased in number, microtubule and microfilaments were disassembled, the nuclei became fewer or shrunk, the growth and attachment were dose-dependently inhibited. CONCLUSIONS: Nicotine and ST can change PDLFs' morphology and structure, they may inhibit the growth and attachment through disruption of the cytoskeleton, suggesting nicotine and ST may have pathological role on human periodontitis.

Cell Adhesion↗
PubMed2003

[Sex distribution of neural tube defects and their birth outcome in high- and low-prevalence areas of China].

OBJECTIVE: To describe and analyze epidemiological characteristics of babies with neural tube defects (NTD) by sex and birth outcome in a high-prevalence and a low-prevalence areas of China. METHODS: Birth defects surveillance data collected from 1992 through 1994, as a part of the Sino-American cooperative project on NTD prevention, were used to classify NTD as four categories, i.e., anencephaly, encephalocele, high-level and low-level spina bifida according to the sites of lesion (high vs. low level lesion were cervicothoracic and lumbosacral, respectively). Each category was sub-classified, according to single or compound defect, as isolated external defects (including those with NTD only) or multiple external defects (including those with NTD and another major external birth defects that is not the sequence of a defect such as cleft lip with or without cleft palate). The rates of anencephalus, encephalocele, high- and low-level spina bifida (SB) in males and females and their sex ratios were calculated, adjusted for urban and rural areas, season, category and birth outcome by sex and sites of lesions (high vs. low). RESULTS: Totally, 784 NTD cases were identified from 326 874 recorded births (including live births, stillbirths and fetal deaths with a gestation age of at least 20 weeks). The prevalence rates of anencephalus (1.30 per 1 000 female births) and high-level SB (3.99) in females were higher than those (0.66 and 1.66 per 1 000 male births) in males in the high-prevalence northern regions; with adjusted prevalence rates of females 1.8 - 2.1 times greater than those of males. In the low-prevalence southern regions, the prevalence of high- (0.32 per 1 000 female births) and low-level SB (0.21) in female were higher than those in males, with high- and low-level SB rate of 0.10 and 0.09 per 1 000 male births), with adjusted rates for females of 1.3 - 1.6 times higher than in males. Isolated NTD accounted for more than 80% of all NTD cases, and the prevalence of isolated NTD in females (2.57) was higher than that in males (1.40). CONCLUSIONS: The sex differences in NTD existed between north and south, in accordance with the phenotype of NTD. It suggested that proportion of high level SB and anencephalus in females could increase as the prevalence of NTD going up, anencephaly, high- and low-level SB had the different genetic and environmental background.

China↗
PubMed2003

[The effect of Class III intermaxillary functional orthopedic force on the remodeling of pubescent rhesus monkeys' temporomandibular joint: an radiographic study].

OBJECTIVE: To study the effect of Class III intermaxillary functional orthopedic force on the remodeling of pubescent Rhesus monkeys' TMJ for different lengths of time. METHODS: Six pubescent Rhesus monkeys were divided into test group and control group. Monkeys in the test group wore TMAIII while the control group did not. Cephalometric technology and CT scanning were employed in this study. RESULTS: 1. Compared with the control groups, the cephalometric results showed that the relationship of the occlusion changed in the test groups. The growth of the maxilla was promoted and the development of the mandible was inhibited, but the mandibular length was not decreased. 2. Compared with the control groups, CT scanning results showed that the posterior space of TMJ in the test group narrowed and the anterior space widened. There was a statistical difference between the test group and the control group(P < 0.01), but no difference within the test group. CONCLUSION: Under Class III Orthopedic therapy, the occlusion relation was changed. The growth of maxilla was promoted and the development of mandible was inhibited. The posterior space of TMJ narrowed and the anterior space widened in test group.

Animals↗
PubMed2003

[Premature, low birth weight, small for gestational age and childhood cerebral palsy].

OBJECTIVE: To investigate the relationship between perinatal risk factors such as premature, low birth weight, small for gestational age and childhood cerebral palsy (CP). METHODS: A cross sectional survey was carried out among 305,263 children aged 1 - 6 years old in seven cities of Jiangsu Province, China from May to July 1997. The perinatal risk factors were analysed. RESULTS: Four hundred and eighty-four cases of CP were found among this population. The prevalence of CP for children aged 1 - 6 years old was 1.59 per thousand. The prevalence of CP were strongly correlated to prematurity (RR = 25.16), low birth weight (RR = 19.63), and also highly correlated to small for gestational age (RR = 4.34). For smaller groups divided by small for gestational age (SGA), appropriate for gestational age (AGA), large for gestational age (LGA) and then by gestational age, prematurity was found to be at high risk in SGA (RR = 9.29), AGA (RR = 28.34) and LGA (RR = 21.41) groups. For groups divided by gestational age and then by SGA, AGA and LGA, SGA was found to have significantly high risk in premature (RR = 1.45), mature (RR = 4.41) and postmature (RR = 3.19) groups. Nine groups were divided by the gestational age along with SGA, AGA and LGA, rates of CP were found to be significantly higher in most groups than in the term AGA group. Compared with the rate of CP in the term AGA group, the RR were calculated and showed as followings (from higher to lower), premature SGA (RR = 40.99), premature AGA (RR = 28.34), premature LGA (RR = 21.08), postmature SGA (RR = 8.39), mature SGA (RR = 4.41) and postmature AGA (RR = 2.63). CONCLUSION: Prematurity and small for gestational age are both independent risk factors for cerebral palsy. Postmaturity and large for gestational age are not risk factors.

Cerebral Palsy↗
PubMed2003

[Study of the methods of determining the isoflavones in herbs of Trifolium pratense extractive].

OBJECTIVE: To study the methods of determining the amount of Isoflavones in red clover extractive. METHOD: RP-HPLC is employed to determine the Isoflavones, with a C18 RP Column, a moble phase of MeOH-CH3CN-0.1%H3PO4 and a detection wavelength of 260 nm. RESULT: After being water-solved, the four groups of flavoes elements satisfactorily separated, the amount of feeding in a range of 0.024-0.336 microg which has a good linear relationship with the peaks, and the total isoflavones determining results repetition, RSD=10.1%. CONCLUSION: A simple, reliable and effective quality-control method is given.

Chromatography, High Pressure Liquid↗
PubMed2002

Activation of Rac1 by shear stress in endothelial cells mediates both cytoskeletal reorganization and effects on gene expression.

Hemodynamic shear stress is a fundamental determinant of vascular remodeling and atherogenesis. Changes in focal adhesions, cytoskeletal organization and gene expression are major responses of endothelial cells to shear stress. Here, we show that activation of the small GTPase Rac is essential for gene expression and for providing spatial information for shear stress-induced cell alignment. Fluorescence resonance energy transfer (FRET) localizes activated Rac1 in the direction of flow. This directional Rac1 activation is downstream of shear-induced new integrin binding to extracellular matrix. Additionally, Rac1 mediates flow-induced stimulation of nuclear factor kappaB (NF-kappaB) and the subsequent expression of intercellular cell adhesion molecule 1 (ICAM-1), an adhesion receptor involved in the recruitment of leukocytes to atherosclerotic plaque. These studies provide a unifying model linking three of the main responses to shear stress that mediate both normal adaptation to hemodynamic forces and inflammatory dysfunction of endothelial cells in atherosclerosis.

Animals↗
PubMed2002

Genomic analysis of smooth muscle cells in 3-dimensional collagen matrix.

The proliferation, differentiation, and protein synthesis of vascular smooth muscle cells (SMCs) play important roles in vascular remodeling. Here, we compared the genetic programming and signaling of SMCs in collagen matrix as a three-dimensional (3-D) environment and on a two-dimensional (2-D) surface. By using DNA microarrays with 9600 genes, we showed that 77 genes were expressed more than twofold and 22 genes were less than one-half in 3-D matrix, when compared with the 2-D condition. The higher expression level of cyclin-dependent kinase inhibitor 1 (p21) in 3-D matrix suggests that p21 may be responsible for the lower proliferation rate in 3-D matrix. The expression level of collagen I was higher in 3-D matrix, suggesting that SMCs in 3-D matrix have increased matrix synthesis. In addition, SMCs in 3-D matrix had less stress fibers and focal adhesions, and a lower level of tyrosine phosphorylation of focal adhesion kinase (FAK). Overexpression of FAK attenuated the expression of p21 and collagen I in 3-D matrix, suggesting that FAK functions as a molecular switch for cell cycle regulation and matrix synthesis. The information generated in this study helps to elucidate the molecular basis of the modulation of SMC phenotypes by the extracellular matrix.

Cell Culture Techniques↗
PubMed2002

Systemic gene therapy in human xenograft tumor models by liposomal delivery of the E1A gene.

The adenovirus type 5 E1A protein has been demonstrated to elicit antitumor effects through the induction of apoptosis, inhibition of cell cycle progression, induction of differentiated epithelial phenotypes, repression of oncogene expression and function, and sensitization to chemotherapeutic agents and radiation. These unique properties have led to use of the E1A gene in adenoviral and lipid-based gene therapy systems, and it has demonstrated antitumor effects in tumor xenograft model systems. However, the delivery systems used in those studies are best suited for local or intratumoral delivery rather than systemic delivery. Because the effective treatment of many primary tumors as well as metastatic disease requires systemic delivery systems, a novel gene delivery system composed of liposome/protamine/DNA (LPD) was investigated for systemic delivery of the E1A gene. Athymic nude mice bearing human breast (MDA-MB-361) or head and neck (WSUHN-31) tumor xenografts were treated i.v. with LPD-E1A, and the expression of E1A protein and effects on tumor growth were assessed. In the MDA-MB-361 breast model, expression of E1A protein was detected in the tumors after LPD-E1A treatment, which was associated with down-regulation of HER-2/neu protein expression and the presence of apoptotic cells. Tumor volume was also smaller in mice treated with LPD-E1A than in controls in both of the xenograft models. Lastly, LPD-E1A in combination with paclitaxel was more effective than LPD-E1A or paclitaxel alone in the MDA-MB-361 model. Additional preclinical and clinical development of LPD-E1A is warranted for the treatment of advanced or metastatic cancer.

Adenovirus E1A Proteins↗
PubMed2002

Differential regulation of Rho GTPases by beta1 and beta3 integrins: the role of an extracellular domain of integrin in intracellular signaling.

Integrins mediate cell adhesion and signal transduction at focal adhesions. Here we investigate the roles of integrin beta subunits in the regulation of actin cytoskeletal structure and the activities of Rho and Rac. The overexpression of beta3 integrin in Chinese hamster ovary cells enhances Rho activity and stress fiber formation, whereas the overexpression of beta1 integrin increases Rac activity and lamellipodia formation. The overexpression of a mutant beta1-3-1 integrin, in which the extracellular I-domain-like sequence of beta1 integrin has been replaced with the corresponding sequence of beta3 integrin, also enhances Rho activity and the formation of stress fibers. Our results demonstrate that beta1 and beta3 integrins differentially regulate the activities of Rho family GTPases and that the extracellular domains of integrin beta subunits play a critical role in transducing the extracellular ligand-binding information into specific intracellular signaling events.

Actins↗
PubMed2002

Evidence for cooperativity between the four binding sites of dimeric ArsD, an As(III)-responsive transcriptional regulator.

ArsD is a trans-acting repressor of the arsRDABC operon that confers resistance to arsenicals and antimonials in Escherichia coli. It possesses two-pairs of vicinal cysteine residues, Cys(12)-Cys(13) and Cys(112)-Cys(113), that potentially form separate binding sites for the metalloids that trigger dissociation of ArsD from the operon. However, as a homodimer it has four vicinal cysteine pairs. Titration of the steady-state fluorescence of ArsD with metalloids revealed positive cooperativity, with a Hill coefficient of 2, between these sites. Disruption of the Cys(112)-Cys(113) site by mutagenesis of arsD, but not the Cys(12)-Cys(13) site, largely abolished this cooperativity, indicative of interactions between adjacent Cys(112)-Cys(113) sites within the dimer. The kinetics of metalloid binding were determined by stopped flow spectroscopy; the rate increased in a sigmoidal manner, with a Hill coefficient of 4, indicating that the pre-steady-state measurements reported cooperativity between all four sites of the dimer rather than just the intermolecular interactions reported by the steady-state measurements. The kinetics of Sb(III) displacement by As(III) revealed that the metalloid-binding sites behave differentially, with the rapid exchange of As(III) for Sb(III) at one site retarding the release of Sb(III) from the other sites. We propose a model involving the sequential binding and release of metalloids by the four binding sites of dimeric ArsD, with only one site releasing free metalloids.

Antimony↗
PubMed2002

The role of the dynamics of focal adhesion kinase in the mechanotaxis of endothelial cells.

The migration of vascular endothelial cells (ECs) is critical in vascular remodeling. We showed that fluid shear stress enhanced EC migration in flow direction and called this "mechanotaxis." To visualize the molecular dynamics of focal adhesion kinase (FAK) at focal adhesions (FAs), FAK tagged with green fluorescence protein (GFP) was expressed in ECs. Within 10 min of shear stress application, lamellipodial protrusion was induced at cell periphery in the flow direction, with the recruitment of FAK at FAs. ECs under flow migrated with polarized formation of new FAs in flow direction, and these newly formed FAs subsequently disassembled after the rear of the cell moved over them. The cells migrating under flow had a decreased number of FAs. In contrast to shear stress, serum did not significantly affect the speed of cell migration. Serum induced lamellipodia and FAK recruitment at FAs without directional preference. FAK(Y397) phosphorylation colocalized with GFP-FAK at FAs in both shear stress and serum experiments. The total level of FAK(Y397) phosphorylation after shear stress was lower than that after serum treatment, suggesting that the polarized change at cell periphery rather than the total level of FAK(Y397) phosphorylation is important for directional migration. Our results demonstrate the dynamics of FAK at FAs during the directional migration of EC in response to mechanical force, and suggest that mechanotaxis is an important mechanism controlling EC migration.

Actins↗
PubMed2002

[Level of plasma lysophosphatidic acid in patients with cerebral ischemic attack, a preliminary study].

OBJECTIVE: To study the level of plasma lysophosphatidic acid (LPA) in patients with TIA, cerebral thrombosis or possible ischemic attack. METHODS: Phospholipid was extracted from plasma of patients with TIA, cerebral thrombosis or possible ischemic attack by organic solvent. Lysophosphatidic acid was isolated further. The quantity of LPA was determined by assaying its phosphorous component. RESULTS: LPA level of patients with TIA, cerebral thrombosis or possible ischemic attack were 2.14 +/- 1.02, 1.50 +/- 0.85, and 1.73 +/- 1.14 micromol/L blood plasma respectively, all significantly higher than that in control group (1.00 +/- 0.70 micromol/L, P < 0.05). The plasma LPA level decreased after anticoagulant treatment. CONCLUSION: As a molecular marker released by activated platelets in vivo, plasma PLA may be valuable in diagnosis of cerebral ischemic attack.

Adult↗
PubMed2002

A low frequency of non-founder BRCA1 mutations in Ashkenazi Jewish breast-ovarian cancer families.

The 185delAG and 5382insC founder mutations account for the majority of mutations identified in BRCA1 in Ashkenazi Jewish breast and breast-ovarian cancer families. Few non-founder BRCA1 mutations have been identified to date in these families. We initially screened a panel of 245 Ashkenazi Jewish breast-ovarian cancer families with an affected proband and at least one other case of breast or ovarian cancer for founder mutations in BRCA1 and BRCA2. Founder mutations were identified in 85 families (185delAG in 44 families, 5382insC in 16 families, and the BRCA2 6174delT in 25 families). The 160 negative families were then screened for the entire BRCA1 gene by a combination of DGGE and PTT. We identified one novel frameshift mutation in BRCA1 in exon 14 (4572del22) that truncated the protein at codon 1485. The family contained three cases of early-onset ovarian cancer (41 years, 43 years, and 52 years) and one case of breast cancer (at age 54 years subsequent to an ovarian cancer). In addition, three missense variants of unknown significance (exon 11 C3832T (P1238L), exon 15 G4654T (S1512I), and exon 15 G4755A (D1546N)) were found in single families. These missense variants have been previously identified in other families [BIC Database] and are considered to be "unclassified variants, favoring polymorphism." Non-founder BRCA1 mutations are rare in Ashkenazi Jewish breast/ovarian cancer families.

Adult↗
PubMed2002

Complex roles of CpG in liposomal delivery of DNA and oligonucleotides.

Unmethylated CpG in bacterial DNA has recently been recognized as a danger signal to the mammalian immune system. This CpG signal can be greatly amplified when DNA is delivered via a lipidic vector. The CpG effects are affected by the administration route, and can be either beneficial or harmful. In this review, we will summarize our current understanding about the mechanism of action of the immunostimulatory motifs. Emphasis will be placed on the discussion of the complicated roles of CpG when CpG DNA or oligonucleotides are administered in vivo using liposomes as a delivery vehicle.

Adjuvants, Immunologic↗