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Biomedical subjects

Li Sheng

Publications and source records attributed to Li Sheng.

At least 19 recordsLinked to original sources
PubMed2007

Predicted stability and structure of (HXeCCH)n (n=2 or 4) clusters and of crystalline HXeCCH.

Ab initio calculations predict the existence of the dimer and tetramer of HXeCCH. The interaction energies are -6.66 and -19.40 kcal mol-1 for the dimer and tetramer, respectively. For both complexes, larger blue shifts of the Xe-H stretching mode are found, while the Xe-C stretching modes are slightly redshifted. The stability and structure of HXeCCH crystals is predicted by density functional theory calculations with periodic boundary conditions. Strong electrostatic interactions are found between the monomers in the crystal. The results are first evidence for the existence of crystalline materials made of a novel class of noble gas molecules.

Journal Article↗
PubMed2006

Stability and structure of oligomers and polymers made of xenon and hydrocarbons: theoretical predictions.

Calculations at B3LYP level predict the existence of three carbon chain oligomers containing HXeC[triple bond]C- branches: C(7)H(8)Xe(2), C(11)H(12)Xe(3), and C(15)H(16)Xe(4). The geometries and NBO charges of the HXeC[triple bond]C- groups in the species are similar to those of the experimental known HXeC[triple bond]CH molecule, and are insensitive to the length of the carbon chain. The structures of the xenon oligomers are very similar to their hydrocarbon precursors. The energetics for C(11)H(12)Xe(3) is calculated to assess the stability of these polymers. Similar to HXeCCH, C(11)H(12)Xe(3) is kinetically stable and protected by a high barrier of 2.47 eV against dissociation to C(11)H(12)Xe(2)+Xe, and is energetically more stable by 1.30 eV than the C(11)H(11)Xe(2)+Xe+H products, which strongly supports the existence of the molecule. Extrapolation of the results for the oligomers suggests the existence of an extended [-CH(2)CH(C[triple bond]CXeH)-](n) polymer. A strategy for preparation is proposed.

Journal Article↗
PubMed2006

Effects of Cilazapril on atrial electrical, structural and functional remodeling in atrial fibrillation dogs.

BACKGROUND AND PURPOSE: The effects of angiotensin-converting enzyme inhibitor on long-term atrial electrophysiologic and structural remodeling are still unclear. The purpose of this study is to investigate the effects of Cilazapril on atrial electrical, structural, and functional remodeling in atrial fibrillation (AF) dogs induced by chronic rapid atrial pacing. METHODS: Twenty dogs were randomly divided into sham-operated group (n = 6), control group (n = 7), and Cilazapril group (n = 7). One thin silicon plaque containing 4 pairs of electrodes was sutured to each atrium. A pacemaker was implanted in a subcutaneous pocket and attached to a screw-in epicardial lead in the right atrial appendage. The dogs in control group and Cilazapril group were paced at 400 beats per minute for 6 weeks. The dogs in Cilazapril group received Cilazapril (0.5 mg x kg(-1) x d(-1)) 1 week before rapid atrial pacing until pacing stop. Before and after 6-week rapid atrial pacing, atrial effective refractory period (AERP) at 8 sites, AERP dispersion, intraatrium conduction time, inducibility, and duration of AF were measured. Transthoracic and transesophageal echocardiographic examinations included left atrium (LA) maximal volume, LA minimal volume, LA ejection fraction, left atrial appendage (LAA) maximal volume, LAA minimal volume, LAA ejection fraction, LAA maximal forward flow velocity, and LAA minimal backward flow velocity were performed. Atrial collagen volume fraction was analyzed by Masson staining. RESULTS: After 6-week rapid atrial pacing, although there was no significant difference in AERP shortening and AERP rate adaptation reduction between the control group and the Cilazapril group, the inducibility and duration of AF were found to be dramatically lower in the Cilazapril group than those in the control group (AF inducibility, 65.7% vs 95.7%, P < .05; AF duration, 531.5 +/- 301.2 vs 1432.2 +/- 526.5 s, P < .01). The post-tachycardia intraatrium conduction times after 6 weeks with Cilazapril were significantly shorter than those in the control group. Cliazapril could partially prevent AERP dispersion increase induced by chronic rapid atrial pacing. Compared with the control group, the LA and LAA volumes were significantly smaller; LA ejection fraction, LAA ejection fraction, LAA maximal forward flow velocity, and LAA minimal backward flow velocity were dramatically higher in the Cilazapril group. The Cilazapril group had a significantly lower percentage of interstitial fibrosis than the control group. CONCLUSIONS: Cilazapril can suppress structural and functional remodeling and prevent the induction and promotion of AF in chronic rapid atrial pacing dogs.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

Use of remote-trip cameras for wildlife surveys and evaluating the effectiveness of conservation activities at a nature reserve in Sichuan province, China.

Monitoring the effectiveness of management activities within reserves is always a complicated task. When the focus of management activities is mammals, it is difficult to monitor their populations in a way that is rapid, effective, and inexpensive. We report on a mammal survey of a reserve in southwest China using remote-trip cameras. We surveyed 329 locations over 2 field seasons in 2002 and 2003. Sixteen species of mammals were detected with these cameras, with four species documented for the first time. After accounting for variation due to slope, aspect, elevation, and habitat type, the distribution of six species was positively associated with the location of conservation stations and/or patrolling routes. Species of medium-sized mammals are excellent candidates for monitoring programs based on these cameras, due to their relative abundance, sufficient size to be detected by the camera units, and sensitivity to human activity. The distribution of mammals relative to management efforts is a relatively rapid means to assess reserve effectiveness. The repeat use of the cameras as part of a monitoring plan should provide a quantifiable measure of reserve effectiveness.

Animals↗
PubMed2006

Investigation on correlation between expression of CD58 molecule and severity of hepatitis B.

AIM: To investigate the correlation between expression of CD58 and severity of hepatitis B. METHODS: The level of soluble CD58 (sCD58) in serum of patients with hepatitis B was detected by enzyme-linked immunosorbent assay. The level of expression of membrane CD58 molecule in PBMC was detected by direct immunofluorescence. The levels of serumal TBIL, DBIL, IBIL, ALT and AST were detected by the automated biochemistry analyzer as well. RESULTS: The levels of sCD58 in serum and membrane CD58 molecule in PBMC of patients with hepatitis B were significantly higher than that in normal controls (P < 0.05). Level of CD58 was related to the levels of serumal TBIL, DBIL, IBIL, ALT and AST. CONCLUSION: The level of CD58 molecule (in both serum and PBMC form) of patients with hepatitis B is related to the degree of liver damage.

CD58 Antigens↗
PubMed2006

High coordination chemically bound compounds of noble gases with hydrocarbons: Ng(CCH)4 and Ng(CCH)6, (Ng=Xe or Kr).

Ab initio calculations predict the existence of the compounds Ng(-C[triple bond]CH)4 and Ng(-C[triple bond]CH)6, where Ng=Xe or Kr. Presently known organic noble gas compounds have a coordination number of two at most. The Ng(-C[triple bond]CH)(4) molecules have D(4h) symmetry, and Ng(-C[triple bond]CH)(6) molecules have O(h) symmetry. The bonding in all these compounds is partly ionic and partly covalent, with significant contributions from both types of bonding. The relatively high vibrational frequencies and the substantial Ng-(C[triple bond]CH) binding energy in these species indicate that these compounds should be fairly stable, at least in cryogenic conditions. These compounds could be a very interesting addition to the range of known organic noble gas compounds. Suggestions are made on possible approaches to their preparation.

Journal Article↗
PubMed2006

Theoretical prediction of chemically bound compounds made of argon and hydrocarbons.

Equilibrium structures, vibrational properties, and stabilities of organo-argon compounds, HArC4H and HArC6H, are studied at the MP2=full/6-311++G(2d,2p) level of theory. Ab initio calculations show that the two molecules are metastable, but protected against the Ar + HY (Y = C4H or C6H) dissociation by high barriers, and these species are energetically stable with respect to the three separate fragments (H + Ar +Y). The implied kinetic stability of HArC4H and HArC6H molecules suggests that these species should very likely be candidates for experimental observation. The results may open possibilities of organic chemistry of light noble gas elements.

Journal Article↗
PubMed2006

[Effect of local mild hypothermia on expression of aquaporin-4 following intracerebral hemorrhage in rats].

OBJECTIVE: To examined the effect of local mild hypothermia on the expression of aquaporin-4 (AQP-4) following intracerebral hemorrhage (ICH) in rats and clarified the mechanism of hypothermia on brain edema formation following ICH. METHODS: Two hundreds and forty male Wistar rats were randomly divided into two groups: the intracerebral hemorrhage (ICH) group, in which autologous arterial blood were stereotaxically injected into right caudate nucleus; the local mild hypothermia (ICH + H) group, in which the rats were given 4 h local mild hypothermia after the injection of blood. Each group was divided into 6 subgroups: control, 6 h, 24 h, 72 h, 5 d and 7 d after operation; Brain water content was determined by dry-wet weight method and the permeability of BBB was measured by Evans-Blue extravasation. RT-PCR and Western blot were respectively used to evaluate AQP-4 mRNA and protein expression. RESULTS: In ICH group, compared with control, ICH significantly increased BWC, the permeability of BBB and the expression of AQP-4 mRNA, all began at 6 h and peaked at 72 h (P < 0.01), the increased protein expression of AQP-4 began at 24 h and also peaked at 72 h (P < 0.01). AQP-4 expression positively correlated, both at the mRNA and the protein level, with the permeability of BBB (r = 0.78 and r = 0.76 respectively). In ICH + H group, compared with ICH group, the elevation of BWC, BBB permeability and AQP-4 protein expression were strongly attenuated at all time point by hypothermia treatment (P < 0.01), while AQP-4 mRNA levels demonstrated a modest attenuation from 48 h. At 72 h, AQP-4 mRNA optical density (A) decreased from 1.25 +/- 0.03 (ICH group) to 1.04 +/- 0.02 (P < 0.01), AQP-4 protein expression (A) decreased from 0.77 +/- 0.08 (ICH group) to 0.25 +/- 0.04 (P < 0.01). CONCLUSIONS: This study indicates that BBB breakdown can increase the expression of AQP-4; local mild hypothermia can significantly reduce brain edema formation after ICH by suppressing the elevation of AQP-4 protein expression; Inhibition of BBB breakdown and the elevation of AQP-4 protein expression with local mild hypothermia appear to contribute to brain protection in this model.

Animals↗
PubMed2006

Lexical-semantic organization in bilingual children: evidence from a repeated word association task.

PURPOSE: This study examined lexical-semantic organization of bilingual children in their 2 languages and in relation to monolingual age-mates. METHOD: Twelve Mandarin-English bilingual and 12 English monolingual children generated 3 associations to each of 36 words. Responses were coded as paradigmatic (dog-cat) or syntagmatic (dog-bark). RESULTS: Within the bilingual group, word association performance was comparable and correlated between 1st and 2nd languages. Bilingual and monolingual children demonstrated similar patterns of responses, but subtle group differences were also revealed. When between-group comparisons were made on English measures, there was a bilingual advantage in paradigmatic responding during the 1st elicitation and for verbs. CONCLUSION: Results support previous studies in finding parallel development in bilinguals' 1st- and 2nd-language lexical-semantic skills and provide preliminary evidence that bilingualism may enhance paradigmatic organization of the semantic lexicon.

Analysis of Variance↗
PubMed2006

Effective induction of type 1 cytotoxic T cell responses in mice with DNA vaccine encoding two hepatitis C virus cytotoxic T lymphocyte epitopes.

The aims of this study were to explain whether a multiple cytotoxic T lymphocyte (CTL) epitope-based anti-hepatitis C virus (HCV) DNA vaccine can induce specific CTL responses to each HCV CTL epitope independently and long-term CD8(+) T cell memory responses, and to determine the cytokine secretion pattern and subtype of epitope-specific cytotoxic T cells. A multi-CTL epitope gene, which consists of two epitopes of HCV (H-2(d)-restricted HCV core(133142) and E1(315322)), was cloned into the eukaryotic expression vector pcDNA3.1. BALB/c mice (H-2(d) restricted) were vaccinated intramuscularly with this multi-CTL epitope-based DNA vaccine. The epitope-specific CTLs against target cells (P815,H-2(d) restricted) pulsed with various CTL epitope peptides were detected by lactate dehydrogenase release assay, and the precursor frequency of epitope-specific CTLs was determined by limiting dilution analysis. Cytokines (interleukin [IL]-2, IL-4, and interferon-) in culture supernatants were determined by enzyme-linked immunosorbent assay. The multi-CTL epitope-based DNA vaccine directed against two HCV CTL epitopes could induce specific CTL responses to each of the two CTL epitopes independently and long-term CD8(+) T cell memory responses. The epitope-specific cytotoxic T cells produced helper T cell type 1 cytokines. This work demonstrated that multiepitope DNA vaccination is a potential strategy to control HCV infection.

Animals↗
PubMed2006

[Relationship between adiponectin and beta-cell function in abdominal visceral obesity women].

OBJECTIVE: To investigate the relationship between adiponectin and beta-cell function in abdominal visceral obesity women. METHODS: Nine abdominal visceral obesity women (VO), 9 normal subjects (C) and 7 patients with type 2 diabetes mellitus (T2DM) were enrolled in the study. Beta-cell function and insulin sensitivity were determined by hyperglycemic clamp, fasting serum adiponectin was assayed by ELISA and regional body fat was measured by MRI. RESULT: The levels of first phase insulin release (FPIR), glucose disposal rates (GDR), insulin sensitivity index (ISI) and adiponectin were significantly elevated in control group compared with VO group and T2DM group. As compared with T2DM group, the levels of adiponectin, FPIR, second phase insulin release (SPIR) and maximum insulin release (INS(max)) increased significantly in VO group. Multiple stepwise regression analysis showed that age, FPIR and GDR were positively correlated to adiponectin (B=0.145, 0.194, 0.277 respectively, all P<0.05), while waist-hip ratio was negatively correlated with adiponectin (B=-7.424, P<0.05). CONCLUSION: The visceral obesity women have lower adiponectin levels, and hyperadiponectinemia may be the link with insulin secretion.

Abdominal Fat↗
PubMed2006

[Inducement of cytotoxic T cell responses in mice by constructing a multi-CTL epitope-based DNA vaccine].

AIM: To construct a multi-CTL epitope-based DNA vaccine to induce specific CTL responses. METHODS: Multi-CTL epitope gene which encoded two HCV epitopes(H-2(d)) was cloned into the eucaryotic expression vector pcDNA3.1 to construct a multi-CTL epitope-based DNA vaccine. BALB/c mice were vaccinated with the DNA vaccine and the specific CTL responses to target cells (P815, H-2(d)) pulsed by different CTL epitope peptide were detected. RESULTS: The multi-CTL epitope-based DNA vaccine which directed against two HCV CTL epitopes induced specific CTL responses to each of the two CTL epitopes independently and enhanced the total specific CTL response. CONCLUSION: The multi-CTL epitope-based DNA vaccine is constructed by using multi-CTL epitopes linked as encoding sequence through natural flanking amino acid residues. It can not only induce specific CTL responses to each CTL epitope independently but also enhance the total specific CTL response.

Animals↗
PubMed2006

Atorvastatin attenuating down-regulation of peroxisome proliferator-activated receptor gamma in preventing cardiac hypertrophy of rats in vitro and in vivo.

PURPOSE: To investigate whether the role of atorvastatin in suppression of cardiac hypertrophy is potentially associated with the change of peroxisome proliferator-activated receptor gamma (PPARgamma) expression, and the anti-inflammatory effect in vitro and in vivo. METHOD: Cardiac hypertrophy was established by angiotensin II in neonatal cardiac myocytes in vitro and incomplete ligation of abdominal aorta of SD rats in vivo. PPARgamma and cytokines mRNA expression was evaluated by RT-PCR, and the rate of protein synthesis in cardiac myocytes by 3H-leucine incorporation. RESULTS: Atorvastatin attenuated downregulation of PPARgamma mRNA and inhibited brain natriuretic peptide (BNP), interleukin-1beta (IL-1beta) and matrix metalloproteinase 9 (MMP9) mRNA expression, as well as 3H-leucine incorporation in a dose-dependent manner in vitro. Furthermore, atorvastatin reduced the mRNA expression of BNP, IL-1beta and MMP9, and enhanced PPARgamma mRNA expression, and diminished the pressure overload-induced increase in the ratio of heart weight to body weight, left ventricular wall thickness and myocyte diameter of rats in vivo. CONCLUSION: Atorvastatin prevents cardiac hypertrophy of rats, probably associated with the modulation of PPARgamma and the inhibition of myocardial inflammation. Atorvastatin may play a role in prevention and treatment of cardiovascular diseases characterized by cardiac hypertrophy.

Animals↗
PubMed2005

Dual-level direct dynamics studies on the reaction Cl + CHBr(2)Cl.

Theoretical investigations are carried out on the multichannel reaction CHBr(2)Cl + Cl by means of direct dynamics methods. The minimum energy path (MEP) is obtained at the BH&H-LYP/6-311G(d,p) level, and energetic information is further refined at the CCSD(T)/6-311+G(2df,2p) (single-point) level. The rate constants for three reaction channels, H-abstraction, Br-abstraction, and Cl-abstraction, are calculated by using the improved canonical variational transition state theory (ICVT) incorporating with the small-curvature tunneling (SCT) correction. The theoretical overall rate constants are in good agreement with the available experimental data and are found to be k=2.58 x 10(-15) T(1.18) exp(-861.17/T) cm(3)molecule(-1)s(-1) over the temperature range 200--2400 K. For the title reaction, H-abstraction reaction channel is the major channel at the lower temperatures, while as the temperature increases, the contribution of Br-abstraction reaction channel should be taken into account. At 2180 K, the rate constants of these two pathways are equal. Cl-abstraction reaction channel is minor channel over the whole temperature region.

Journal Article↗
PubMed2005

Association between a dopamine-4 receptor polymorphism and blood pressure.

BACKGROUND: Dopamine receptor genes are candidates for hypertension susceptibility. Locally released dopamine increases renal sodium excretion, and defective renal dopamine receptor signaling has been shown to play a role in hypertension. Dopamine-4 receptors are expressed in juxtaglomerular and cortical collecting cells, where dopamine activation could alter sodium and water metabolism and affect blood pressure (BP). The dopamine-4 receptor (DRD4) gene has a 16 amino acid (48 base pairs [bp]) repeat polymorphism located in exon 3 where a G-protein binding area is encoded. The long allele (defined as at least one 7 to 10 repeat) has been associated with the personality trait Novelty Seeking and with substance abuse, but associations between dopamine-4 receptor polymorphisms and BP have not been reported. METHODS: We genotyped 479 female and 385 male subjects of white ethnicity at the DRD4 repeat polymorphism site and classified each subject as having either the long or short genotype. RESULTS: We found associations between the DRD4 long allele and increased systolic BP (P = .031), diastolic BP (P = .034), and a history of regular alcohol use (P = .008). Furthermore, for systolic BP (P = .009) and pulse pressure (P = .002), we found evidence for an interaction between dopamine-4 receptor alleles and age, indicating that the effects of dopamine-4 receptor variants on BP increase with age. CONCLUSION: In this white population, the long variant of the DRD4 gene is associated with a 3-mm Hg higher systolic and 2-mm Hg higher diastolic BP.

Adult↗
PubMed2005

The precocious two-year-old: status of the lexicon and links to the grammar.

This is a study of the lexical and grammatical abilities of 16 lexically precocious talkers. These children, aged 2;0 were compared to their age-matched peers, 22 typical talkers aged 2;0, and their expressive vocabulary-matched peers, 22 typical talkers aged 2;6. Individual differences in children's lexical knowledge at 2;0 were stable--evident in parent report, laboratory observation, and an experimental fast-mapping paradigm. In accordance with the continuity hypothesis, the lexically precocious children were also grammatically precocious, having a greater representation of grammatical types and tokens and more advanced combinatorial language than their typical age-matches. Their grammatical development was very similar to that of their older vocabulary-matched peers. Limits on continuity were highly constrained with no true dissociation between the lexicon and the grammar in 33 cases examined. We conclude that, among two-year-olds, grammatical development is more tightly associated with the size of the lexicon than with chronological age.

Age Factors↗