Biomedical subjects

Ying Li

Publications and source records attributed to Ying Li.

At least 109 records · Page 6Linked to original sources

PubMed2006

Nonlinear optical properties of alkalides Li+(calix[4]pyrrole)M- (M = Li, Na, and K): alkali anion atomic number dependence.

A new type of alkalide compound, Li+(calix[4]pyrrole)M- (M = Li, Na, and K), is presented in theory, which may be stable at room temperature. It has been shown by our calculations that the first hyperpolarizability (beta) is considerably large by means of the density functional theory method. The beta values are determined at the B3LYP/6-311++G level (for the alkali atoms the 6-311++G(3df) basis set is employed) as 8.9 x 103, 1.0 x 104, and 2.4 x 104 au for M = Li, Na, and K, respectively. These beta values are much larger than that of electride Li+(calix[4]pyrrole)e- (beta = 7.3 x 103 au) by a factor of 1.2 to 3.4. Comparing to the cryptand calix[4]pyrrole, the beta values of Li+(calix[4]pyrrole)M- are enhanced by 20-60 times. It is revealed, for the first time, that the beta value of alkalide compounds depends on the atomic number of the alkali anion, and it can be enhanced by choosing the akali anions with larger atomic numbers. The alkali anion in the alkalide compound decreases the transition energy and also increases the oscillator strength of the main transition, consequently the beta value is enhanced. This study proposes such a novel way to synthesize and design new NLO materials by using the alkali atom with a larger atomic number to create an anion in alkalide compounds.

Journal Article↗

PubMed2006

Regulation of mitochondria distribution by RhoA and formins.

The distribution of mitochondria is strictly controlled by the cell because of their vital role in energy supply, regulation of cytosolic Ca2+ concentration and apoptosis. We employed cultured mammalian CV-1 cells and Drosophila BG2-C2 neuronal cells with enhanced green fluorescent protein (EGFP)-tagged mitochondria to investigate the regulation of their movement and anchorage. We show here that lysophosphatidic acid (LPA) inhibits fast mitochondrial movements in CV-1 cells acting through the small GTPase RhoA. The action of RhoA is mediated by its downstream effectors: formin-homology family members mDia1 in mammalian cells and diaphanous in Drosophila. Overexpression of constitutively active mutant forms of formins leads to dramatic loss of mitochondrial motility and to their anchorage to actin microfilaments. Conversely, depletion of endogenous diaphanous protein in BG2-C2 cells by RNA interference (RNAi) stimulates the mitochondrial movement. These effects are not simply explained by increased cytoplasm viscosity resulting from an increased F-actin concentration since stimulators of Arp2/3-dependent actin polymerization and jasplakinolide do not cause inhibition. The observed effects are highly specific to mitochondria since perturbations of diaphanous or mDia1 have no effect on movement of other membrane organelles. Thus, mitochondrial movement is controlled by the small GTPase RhoA and this control is mediated by formins.

Animals↗

PubMed2006

Homocysteine, hRIP3 and congenital cardiovascular malformations.

Elevated serum homocysteine (Hcys) levels have been suggested to contribute to congenital cardiovascular malformations, neural tube defects, and cardiovascular diseases. To investigate the mechanisms resulting in cardiovascular diseases and birth defects, Kuang-Hueih Chen et al. identified and characterized a novel gene, named rHCY2, whose expression was markedly up-regulated when Hcys was elevated in rat. In vivo, rHCY2 gene could induce chicken embryonic cells apoptosis and embryonic malformations. Its N-terminal kinase domain is apparently similar to human receptor-interacting serine-threonine kinase 3 (hRIP3). In view of this, we hypothesize that a link between the teratogenic effects of Hcys and hRIP3 is theoretically plausible. However, given the lack of data on the topic, it remains to be seen whether an elevated serum Hcys level will increase the expression of hRIP3. Using normal and abnormal human fetal hearts and cultured normal human fetal cardiomyocytes, we show that congenital cardiovascular malformations are associated with the overexpression of hRIP3, and evidence is found for a certain association between overexpression of hRIP3 and homocysteine-induced congenital cardiovascular malformations. Folic acid and anti-hRIP3 antibodies seem to favor maintenance of the shape and ultrastructure of cultured human fetal cardiomyocytes.

Amino Acid Sequence↗

PubMed2006

Effects of oocyte activation and sperm preparation on the development of porcine embryos derived from in vitro-matured oocytes and intracytoplasmic sperm injection.

The objective was to determine the effects of various methods of oocyte activation and sperm pretreatment on development of porcine embryos derived from in vitro-matured oocytes and intracytoplasmic sperm injection (ICSI). The second polar body was extruded in the majority (>78.4%) of in vitro-matured (IVM) oocytes 4h after electrical pulse activation. In embryos generated by ICSI and sham-ICSI, a combination of an electrical pulse, with various chemical activators 4 h later, improved (P < 0.05) blastocyst formation rate compared to activation only with a pulse. Treatment with 6-dimethylaminopurine (DMAP) after electrical activation significantly increased the oocyte activation rate. The effects of exposure of sperm to repeated freeze-thaw cycles (without cryoprotectant) on oocyte activation and the effects of sperm pre-incubated with dithiothreitol (DTT) or Triton X-100 on early embryo development were also examined. Blastocyst formation rates after ICSI did not differ between motile sperm and those rendered immotile by one-time freezing and thawing without cryoprotectant. However, sperm rendered immotile by three cycles of freezing/thawing without cryoprotectant had a significantly lower blastocyst formation rate. Although oocytes injected with sperm pre-incubated with Triton X-100 had a higher normal fertilization rate than those pre-incubated with DTT or one-time frozen/thawed sperm, rates of blastocyst formation and cell numbers were similar among the three groups. In conclusion, various methods of oocyte activation and sperm preparation significantly affected the developmental capacity of early porcine embryos derived from IVM and ICSI.

Animals↗

PubMed2006

Gender and risk factor dependence of cerebral blood flow velocity in Chinese adults.

BACKGROUND AND PURPOSE: The objective of this study is to determine if and how cerebral blood flow velocity and stroke risk factors are related in a stroke free population. METHODS: This cross-sectional study recruited 1323 stroke-free subjects, aged 42-73 years, from a county region in China. Systolic blood flow velocities in cerebral arteries were detected with trans-cranial Doppler. Key factors, such as anthropometry, life-style, medication use, blood pressure and blood biochemical analysis were investigated at the same time. RESULTS: In women, even controlled for major cardiovascular risk factors, cerebral blood flow velocities of common carotid artery, internal carotid artery, middle cerebral artery, anterior cerebral artery and posterior cerebral arteries decreased significantly with age (from 43.8 to 39.3, 48.0 to 42.6, 97.7 to 82.8, 79.2 to 69.4 and 44.1 to 39.7 cm/s in the range of 42-73 years old, p < 0.01 for each). In men, however, this inverse trend only existed in common carotid artery (from 45.6 to 41.7 cm/s, p < 0.01). Multivariate regression showed that most established cardiovascular risk factors (e.g. hypertension, hypercholesterolemia, diabetes mellitus and overweight/obesity) were associated with decreased blood flow velocity in the extra-cranial arteries. However, this association was not present (e.g. diabetes and overweight/obesity) or was inversed (e.g. hypertension and hypercholesterolemia) in the intra-cranial arteries. CONCLUSION: Extra-cranial blood flow velocity is significantly and inversely related to age and cardiovascular risk factors. The relationship between intra-cranial blood flow and risk factors changes and may depend on gender. These finding may have importance in the determination of mechanisms of stroke.

Adult↗

PubMed2006

Identification of a nuclear matrix attachment region like sequence in the last intron of PI3Kgamma.

MARs are not only the structure bases of chromatin higher order structure but also have much biological significance. In this study, the whole sequence of about 100 kb in length from BAC clone of GS1-223D4 (GI: 5931478), in which human PI3Kgamma gene is localized, was analyzed by two online-based computer programs, MARFinder and SMARTest. A strong potential MAR was predicted in the last and largest intron of PI3Kgamma. The predicted 2 kb MAR, we refer to PIMAR, was further analyzed through biochemical methods in vitro and in vivo. The results showed that the PIMAR could be associated with nuclear matrices from HeLa cells both in vitro and in vivo. Further reporter gene analysis showed that in the transient transfection the expression of reporter gene linked with reversed PIMAR was repressed slightly, while in stably integrated state, the luciferase reporter both linked with reversed and orientated PIMAR was enhanced greatly in NIH-3T3 and K-562. These results suggest that the PIMAR maybe has the capacity of shielding integrated heterogeneous gene from chromatin position effect. Through combination of computer program analysis with confirmation by biochemical methods, we identified, for the first time, a 2 kb matrix attachment region like sequence in the last intron of human PI3Kgamma.

Animals↗

PubMed2006

Selective refocusing pulses in magic-angle spinning NMR: characterization and applications to multi-dimensional protein spectroscopy.

Band-selective pulses are frequently used in multi-dimensional NMR in solution, but have been used relatively less often in solid-state NMR applications because of the complications imposed by magic-angle spinning. In this work, we examine the frequency profiles and the refocusing efficiency of several commonly employed selective general rotation pi pulses through experiments and numerical simulations. We demonstrate that highly efficient refocusing of transverse magnetization can be achieved, with experiments that agree well with numerical simulations. We also show that the rotational echo is shifted by a half rotor period if a selective pulse is applied over an integer number of rotor periods. Appropriately synchronizing indirect evolution periods with selective pulses ensures proper phasing of cross peaks in 2D spectra. The improved performance of selective pulses in multi-dimensional protein spectroscopy is demonstrated on the 56-residue beta1 immunoglobulin binding domain of protein G (GB1).

Carbon Isotopes↗

PubMed2006

Distinct expression and localization of serine protease HtrA1 in human endometrium and first-trimester placenta.

Mammalian embryos cannot survive without the placenta. Development of the human placenta requires trophoblast proliferation, differentiation, and invasion as well as highly coordinated modulation of the maternal uterus. HtrA1 is a member of the recently identified mammalian HtrA (high temperature requirement factor A) serine protease family with a high level of expression in the placenta. In this study, we examined whether HtrA1 expression (mRNA and protein) is associated with placental development in the human. HtrA1 is up-regulated in both endometrial glands and decidual cells during endometrial preparation for embryo implantation and during first-trimester pregnancy at placentation. HtrA1 expression was also detected in certain trophoblast subtypes during early pregnancy. The villous syncytiotrophoblast and cytotrophoblast showed the strongest expression while the interstitial extravillous trophoblast showed the lowest or no expression of HtrA1. The distinct distribution of HtrA1 at the maternal-trophoblast interface suggests that HtrA1 may play a role in placental development.

Decidua↗

PubMed2006

Genotyping fetal paternally inherited SNPs by MALDI-TOF MS using cell-free fetal DNA in maternal plasma: influence of size fractionation.

The determination of fetal point mutations from fetal cell-free DNA (cf-DNA) in maternal plasma is technically challenging due to the preponderance of maternal sequences. It has recently been shown that fetal cf-DNA sequences are smaller than maternal ones and that the selection of small cf-DNA fragments by size fractionation by agarose gel electrophoresis leads to the enrichment of fetal cf-DNA sequences, thereby permitting the detection of otherwise masked fetal point mutations. In a separate development, the use of MALDI-TOF MS has also been shown to facilitate the detection of fetal point mutations from cf-DNA in maternal plasma. In this study, a combination of these approaches was examined. cf-DNA was extracted from 18 maternal plasma samples, 10 taken at term and 8 obtained early in the second trimester. A total of 41 SNP loci were examined in size-fractionated and total cf-DNA using either a conventional homogeneous MassEXTEND (hME) assay or a nucleotide-specific single allele base extension reaction (SABER) assay. The analysis of total cf-DNA indicated that size fractionation considerably enhanced the sensitivity of the standard hME assay, especially for samples taken early in pregnancy. Size fractionation also rendered the signals obtained by the SABER assay more precise.

Alleles↗

PubMed2006

Royal crown-shaped electride Li3-N3-Be containing two superatoms: new knowledge on aromaticity.

The structure and aromaticity of a royal crown-shaped molecule Li(3)-N(3)-Be are studied at the CCSD(T)/aug-cc-pVDZ level. This molecule is a charge-separated system and can be denoted as Li(3) (2+)N(3) (3-)Be(+). It is found that the Li(3) (2+) ring exhibits aromaticity mainly because the Li(3) (2+) ring can share the pi-electron with the N(3) (-3) ring. The 4n+2 electron counter rule can be satisfied for the Li(3) (2+) subunit if the shared pi valence electron of N(3) (3-) subunit is also taken into account. This new knowledge on aromaticity of a ring from the interactions between subunits is revealed first time in this paper. Li(3)-N(3)-Be can be also regarded as a molecule containing two superatoms (Li(3) and N(3)), which may be named as a "superomolecule." Li(3)-N(3)-Be is a new metal-nonmetal-metal type sandwich complex. The N(3) (3-) trianion in the middle repulses the electron clouds of the two metal subunits (mainly to the Li(3) superatom) to generate an excess electron, and thus Li(3)-N(3)-Be is also an electride. This phenomenon of the repulsion results in: (a) the HOMO energy level increased, (b) the electron cloud in HOMO distended, (c) the area of the negative NICS value extended, and (d) the VIE value lowered. So the superomolecule Li(3)-N(3)-Be is not only a new metal-nonmetal-metal type sandwich complex but also a new type electride, which comes from the interaction between the alkali superatom (Li(3)) and the nonmetal superatom (N(3)).

Journal Article↗

PubMed2006

Prospective cohort study of the association between use of low-dose oral contraceptives and stroke in Chinese women.

PURPOSE: To clarify the association between use of widely distributed low-dose combined oral contraceptives (COCs) in China and the risk of stroke in order to decrease adverse reactions to COCs. METHODS: A prospective surveillance cohort study was undertaken in 25 towns in two counties in Jiangsu Province, China. Women (44,408 ) on hormonal contraceptives (HC) and 75,230 women with an intrauterine device (IUD) were followed up from July 1997 to June 2000 to study the difference in the incidence of stroke. RESULTS: The incidence of haemorrhagic stroke (age- and county-standardised rate) was far higher than that of ischaemic stroke (34.74 vs. 11.25 per 100,000 person years) among HC cohort. The relative risk (RR) of incidence of haemorrhagic stroke in the HC cohort (52 cases) was 2.72 times compared with that in the IUD cohort (23 cases). Compared with IUD users, the current users of HC had a higher RR of 4.20 (95%CI, 2.11-8.36) of haemorrhagic stroke, and still reached 2.17 (95%CI, 1.16-4.06) among past users after they stopped taking COCs for more than 10 years. The RR of haemorrhagic stroke was 3.09 (95%CI, 1.26-7.57) among women who had last used low-dose COCs during the previous 5 years. In women aged less than 45 years, compared to IUD users, the haemorrhagic stroke was strongly associated with current use of low-dose combined norethisterone pills, with RR being 19.06 (95%CI, 3.08-118.03). CONCLUSIONS: There is an increased risk of haemorrhagic stroke among Chinese users of long-term low-dose oral contraceptives, which appears to persist long after discontinuation.

Adult↗

PubMed2006

Relationship between clinical predictors and tubulointerstitial damage in adult-onset primary nephrotic syndrome.

BACKGROUND: Tubulointerstitial damage (TID) is an important mediator in the progression of chronic proteinuric nephropathies. Our aim in this study was to evaluate the relationship between several clinical predictors and TID in adult-onset primary nephrotic syndrome in China. METHODS: One hundred ninety-five adult inpatients who were diagnosed with primary nephrotic syndrome based on clinical presentation and biopsy results were enrolled in this study from March 2003 to September 2005. The degree of TID was graded by a semiquantitative method including <2 score and >or=2 score. RESULTS: In all patients, the rate of glomerulosclerosis was correlated with the severity of TID. Serum creatinine and uric acid (r = 0.183, p = 0.012 and r = 0.377, p = 0.00001, respectively) but not serum lipid or total 24-h urinary protein were related with TID. In 64 patients, urinary excretion of IgG (r = 0.443, p = 0.00001) but not of albumin, transferrin, retinal-binding protein, or alpha1-microglobulin were significantly associated with the extent of TID. Proteinuria selectivity index based upon IgG also correlated significantly with the extent of TID (p = 0.0001) (score 0-1 vs. score >or=2). CONCLUSIONS: These results showed that serum creatinine and uric acid, the excretion of urinary IgG and proteinuria selectivity index based upon IgG, were highly correlated with the severity of TID in adult-onset primary nephrotic syndrome. These clinical parameters might be useful for predicting the development and progression of proteinuric nephropathy as independent risk factors.

Adolescent↗

PubMed2006

Actin homolog MreBH governs cell morphogenesis by localization of the cell wall hydrolase LytE.

MreB proteins are bacterial actin homologs involved in cell morphogenesis and various other cellular processes. However, the effector proteins used by MreBs remain largely unknown. Bacillus subtilis has three MreB isoforms. Mbl and possibly MreB have previously been shown to be implicated in cell wall synthesis. We have now found that the third isoform, MreBH, colocalizes with the two other MreB isoforms in B. subtilis and also has an important role in cell morphogenesis. MreBH can physically interact with a cell wall hydrolase, LytE, and is required for its helical pattern of extracellular localization. Moreover, lytE and mreBH mutants exhibit similar cell-wall-related defects. We propose that controlled elongation of rod-shaped B. subtilis depends on the coordination of cell wall synthesis and hydrolysis in helical tracts defined by MreB proteins. Our data also suggest that physical interactions with intracellular actin bundles can influence the later localization pattern of extracellular effectors.

Actins↗

PubMed2006

Molecular evolution of prolactin gene family in rodents.

In this study, we identified two novel members of prolactin gene family in rat by blast searches against the published genomic database. A further analysis showed that gene duplications leading to PRL gene family in rodents occurred after rodents diverged from other mammals. Major reorganization of the gene loci in rodents was largely completed before the split of rat and mouse. But PL-I and PL-II genes are the exceptions, which have clustered in a species-specific manner in the phylogenetic tree. By combining results from gene conversion testing, relative chromosomal location comparison and estimated time for gene duplication, we believe that rodent PL-1 and PL-II genes are species-specific and are the results of serial duplications which occurred after the divergence of mouse and rat. Our analysis also reveals that continual gene duplication and divergence occurred during the evolution of rodent PRL gene family.

Amino Acid Sequence↗

PubMed2006

Olfactory ensheathing cells: ripples of an incoming tide?

Until now, brain and spinal cord injuries that sever nerve fibres have resulted in a degree of incurable functional loss. An incoming tide of research is now beginning to challenge this as yet unbreached sea wall. One of the most promising approaches involves a recently discovered type of cell, the olfactory ensheathing cell, which can be obtained from the adult nasal lining. In animal models transplantation of cultured olfactory ensheathing cells into an injured spinal cord induces regeneration, remyelination of severed spinal nerve fibres, and functional recovery. Although several clinical centres worldwide have shown an interest in applying this approach to patients with spinal cord injury, there is no agreement on cell technology, and claims of beneficial results lack independent confirmation. Important aspects still need to be worked out at the laboratory level. Overall, the outlook is optimistic, but there is still some way to go.

Animals↗

PubMed2006

The politics of sexual orientation issues in American schools.

Schools are increasingly expected to address the needs of gay, lesbian, bisexual, and transgender students. However, the controversial nature of sexual orientation programs and policies makes this a politically sensitive undertaking. This empirical study analyzes the extent to which public school districts across the United States have implemented policy recommendations and describes, according to 4 theoretical policy models, factors that influence their ability to do so. The survey found that most districts have not institutionalized recommended policies or programs. Recommendations for school health professionals based on factors found to be significantly associated with the implementation of programs are discussed.

Adolescent↗

PubMed2006

Cell-free DNA in maternal plasma: is it all a question of size?

Fetal cell-free DNA (cf-DNA) represents only a small fraction of the total cf-DNA in maternal plasma. This feature has rendered it difficult to reliably distinguish fetal alleles which are not very disparate from maternal ones, such as those involving point mutations, by conventional polymerase chain reaction (PCR)-based approaches. It has recently been shown that cell-free fetal DNA molecules have a smaller size than comparable cf-DNA molecules of maternal origin, and that this feature can be exploited for the selective enrichment of fetal DNA sequences, thereby permitting the detection of otherwise masked fetal genetic traits. By the use of this approach, we have shown that it is possible to detect fetal genetic loci for microsatellite markers, as well as point mutations involved in disorders such as achondroplasia and beta-thalassemia.

Achondroplasia↗

PubMed2006

Detection of SNPs in the plasma of pregnant women and in the urine of kidney transplant recipients by mass spectrometry.

Recently, it has been discovered that cell-free fetal DNA is smaller than corresponding maternal DNA. Therefore, circulating fetal DNA can be enriched by size-fractionation. Such a selection improves the non-invasive prenatal diagnosis of paternally inherited single gene mutations. Recent studies showed that MALDI-TOF mass spectrometry (MS) can be used to reliably detect fetal-specific single-nucleotide polymorphisms (SNPs) in maternal plasma. In this study, we looked at whether the size-fractionation approach could improve the detection of paternally inherited SNPs by MS assay. Our results indicated that the size-fractionation approach improved the analysis of paternally inherited SNP alleles. Our previous studies showed that donor-derived STR sequences could be detected in the urine of kidney transplant recipients. Here, we also examined whether donor-specific SNPs could be detected in recipient's urine by MS.

DNA↗