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Biomedical subjects

Lei Zhang

Publications and source records attributed to Lei Zhang.

At least 163 records · Page 9Linked to original sources
PubMed2006

[Capacity of monitoring system on birth defects during 1990s in China].

OBJECTIVE: To understand the status and capacity of monitoring system on birth defects in China. METHODS: Data regarding 27 groups of birth defects from 57 monitoring programs in World Atlas of Birth Defects (2nd Edition) published by WHO/ICBDMS/EUROCAT/HGP and descriptive analysis by their ranking and contribution were carried out. RESULTS: Both hospital-based (Chinese Birth Defects Monitoring Network, CBDMN) and population-based (Birth Defect Surveillance System in Thirty Counties of Four Provinces, Beijing) monitoring systems showed the same characteristics as below: (1) Not enough groups were monitored, with trisomy 13/18 and congenital heart disease not reported. (2) Prevalence on those 'easily observed' group was high and cleft lip with or without cleft palate in CBDMN ranked 5 among 57 programs, with similar situation in polydactyly. (3) While prevalence rates of internal system and choromosal anomaly were low, CBDMN ranked 56 with Beijing the only non-reported city among all the 57 programs. (4) Unreasonable relationship was seen with prevalence of cleft lip was 5.76,4.02 times higher than that of cleft palate in CBDMN and in Beijing program. Which was 1.58 times of the world's means. Prevalence rates of anencephaly and total anotia/microtia rose 10.39% while spina bifida, hydrocephaly, and gastroschisis had a 4%-5% increase. The prevalence of hypospadias decreased by 4.13% and Down syndrome by 3.02%. CONCLUSION: The capacity of birth defects monitoring, both hospital-based and population-based, was poor in the 1990s, in China.

Capacity Building↗
PubMed2006

[Reliability evaluation for thirteen parameters describing anteroposterior apical base relationship in Angle Class II division 1 patients].

OBJECTIVE: To study 13 different cephalometric measurements of the anteroposterior jaw relationship in Angle Class II division 1 statistically and geometrically, and to discuss the effects of various factors on this relationship, and then to choose the most adequate measurements. METHODS: 120 patients with skeletal malocclusion Angle Class II division 1 were selected. The samples consisted of 60 men and 60 women between 20 to 28 years of age. Lateral cephalometric radiograph for each patient was taken in natural head posture by the same operator. A wire plumb line and suspended weight recorded the true vertical on each radiograph. The subject was then asked to determine the self-balanced position of the head. After determining the self-balanced neutral position, the subject was asked to look into his/her own eyes in the mirror. ANB angle, A-B plane angle, Wits appraisal, AF-BF distance, AXB angle, AB/SN4 distance, AB/PP distance, AXD angle, AD/SN distance, SGn/AB angle, APDI, FABA angle, beta angle and AB/HP distance were measured. Coefficient correlations among measurements were tabulated to determine which combination would produce a higher value. Fuzzy grouping analysis was made. RESULTS: Statistically significant and highly correlated relationships was found among many measurements except Wits appraisal and SGn/AB angle. The thirteen measurements could be divided into five clusters. CONCLUSION: The cephalometric measurements except Wits appraisal and SGn/AB angle can be used to evaluate anteroposterior jaw relationship. The AB/SN4 distance is the most adequate measurements. ANB angle, A-B plane angle, AF-BF distance, AXB angle, AB/PP distance, APDI, FABA angle and beta angle are similar in describing anteroposterior apical base relationship in Angle Class II division 1 patients.

Cephalometry↗
PubMed2006

[Posterior glass fiber-reinforced composite resin-bonded fixed partial dentures: A 3-dimensional modeling and finite element numerical analysis].

The method of modeling and mesh generation about 3-unit tooth/restoration complex were established. The three-dimensional finite element models were subjected to four types of occlusal load applied to pontic element to evaluate 3 fiber framework designs and 3 cavities preparation configurations. By comparing the difference of stress distribution, following conclusions were obtained: the principal stress under buccal-lingual cusp load in traditional fiber framework pontic increased by 6.22% compared to that in pure composite resin pontic; optimized fiber framework obviously reduced stress level under any load; modified cavities exhibited better stress transfer and decreased share stress at adhesive interface than traditional cavities.

Composite Resins↗
PubMed2006

[Polymorphism of five short tandem repeat loci on chromosome X in Hebei Han population].

OBJECTIVE: To investigate the polymorphism of DXS6801, DXS6809, DXS7423, DXS7424, DXS9902 five loci in Hebei Han population. METHODS: The PCR products were detected by the polyacrylamide gel electrophresis and DNA sequencing analysis. RESULTS: Among 114 irrelative males and 118 irrelative females from Hebei Han population, 31 alleles were found in the 5 loci. One hundred and one haplotypes of the male were detected and the haplotype diversity reached 0.9975. CONCLUSION: The five loci are relatively abundant in polymorphic information for identification and paternity test. And the obtained data of Hebei Han population can be applied to the X-short tandem repeat genetic data bank.

Alleles↗
PubMed2006

[Primary study on acid tolerance mechanism of a wild aciduric Rhizobium strain isolated from Pueraria lobata].

An aciduric Rhizobium strain, named as PR389, was isolated from the nodule of wild Pueraria lobata which grew in yellow soil (pH 4.6) on the Jin-yun Mountain in Bei-bei, Chong-qing city. The isolated strain, which could grow under pH 4.6 distinct from the optimal pH 6.5-7.5 for rhizobium, showed some typical features of aciduric rhizobium. This was also confirmed by the proton flux assay. Compared to the acid-sensitive Rhizobium strain PR21, the cell membrane of PR389 could hold back excessive H entering cell. This feature can protect PR389 from harm of acid. In the test of acid tolerance, the aciduric ability of strain PR389 under low acidic (pH 3.8) was restrained by antibiotic chloramphenicol. It was speculated that special proteins in the cells of PR389 could be induced and synthesized in acidic environment.

Acids↗
PubMed2006

[The cloned ctxA gene of vibrio cholerae expresses in E. coli].

OBJECTIVE: To construct the expression vector of Vibrio cholerae ctxA gene, and realize the Vibrio cholerae ctxA gene to express in E. coli, and lay a basis for future research on the immunogenicity and immunoadjuvant. METHODS: The ctxA gene, an cholera toxin subunit gene (ctxA) of Vibrio cholerae, was obtained by polymerase chain reaction (PCR) from DNA of Vibrio cholerae, and cloned into prokaryotic expressed vector pET32a(+) with thioredoxin (Trx) gene. The recombinant plasmid (pET-ctxA) was analyzed to identify with restriction-endonuclease digestion, PCR and DNA sequencing analysis. And then the pET-ctxA was transferred into E. coli strain BL21 (DE3) for transformation. The ctxA expression of pET-ctxA was induced with isopropy-beta-D-thiogalactoside (IPTG) and the fused protein Trx-CTA was examined by SDS-PAGE and Western blot techniques. RESULTS: Restriction endonuclease digestion, PCR and DNA sequencing analyses showed that the ctxA gene of 787 bp was amplified from Vibrio cholerae DNA, and the recombinant plasmid pET-ctxA was successfully constructed, and the ctxA expression in prokaryotic cell was detected by SDS-PAGE and Western blot techniques. CONCLUSION: The ctxA gene of Vibrio cholerae, in fused protein form with Trx, got a high expression in E. coli.

Cholera Toxin↗
PubMed2006

Influence of temperature on performance of anaerobic digestion of municipal solid waste.

The influence of temperature on the performance of anaerobic reactors for treating the organic fraction of municipal solid waste (OFMSW) was studied. Batch digestion of OFMSW was carried out for 32 d at different temperature (25 degrees C, 35 degrees C, 45 degrees C and 55 degrees C) conditions for total solid concentrations (TS) 17% with the ratio of total organic carbon to nitrogen (C/N) being, 25:1 respectively, while keeping other parameters constant such as inoculum, start-up pH, reactor volume (2 L) and so on. Temperature can influence the methanogenic bacteria activity, accordingly inhibiting the OFMSW biodegradation and stabilization efficiency. Anaerobic reactors excelled at TS reduction, total volatile solid reduction, chemical oxygen demand reduction, increasing cumulative biogas production, whose rate was at temperature (35 degrees C and 55 degrees C) conditions. Methane concentration in the biogas was above 65% in four reactors. In addition, the fluctuation of temperatures resulted in the biogas production variation. The data obtained indicated that temperature had a significant influence on anaerobic process.

Bacteria, Anaerobic↗
PubMed2006

[Anterior chamber phakic intraocular lens implantation in highly myopic eyes].

OBJECTIVE: To investigate the stability, predictability and safety of angle-supported phakic intraocular lens (IOL) implantation in high myopia. METHODS: Seventy-six myopic eyes of 40 patients treated with anterior chamber angle-supported phakic IOL (Phakic6H) implantation were followed. The average myopia diopter was (-15.89 +/- 3.78) D (-9.50 to -26.25 D) and the best corrected visual acuity (BCVA) was (0.82 +/- 0.20) (0.5 to 1.0). The average follow-up time was 12 months. All the treated eyes were observed for anterior segment changes, uncorrected visual acuity (UCVA), BCVA, refraction, intraocular pressure (IOP) and corneal endothelium preoperatively and postoperatively. All data were analyzed in statistics. RESULTS: One year after the surgery, the average UCVA was (1.00 +/- 0.35) (0.3 to 1.5) and BCVA was (1.18 +/- 0.29) (0.5 to 1.5). The average residual refraction was (-0.40 +/- 0.64) D (-2.00 to +0.50 D). In 96.1% of eyes, the average residual refraction was within +/- 1.0 diopter. The average corneal endothelial count before and one year after the surgery was (3174 +/- 248)/mm(2) and (3067 +/- 320)/mm(2) (P < 0.01) respectively. The intraocular pressure before and one year after the surgery was (16.12 +/- 2.32) mmHg and (15.29 +/- 3.38) mmHg (P < 0.05) respectively. Two patients (4 eyes) complained of halo and glare. One patient's (2 eyes) pupils were oval and another one (2 eyes) showed decentered phakic IOL. Macular hemorrhage occurred in one patient (2 eyes) after eight months of surgery. CONCLUSIONS: Angle-supported phakic IOL implantation is effective for treatment of high myopia and the results are predictable. It deserves further clinical investigation. The effectiveness and safety of this kind of phakic IOL should be further observed for a long period of time.

Adult↗
PubMed2005

Anti-oxidative effect of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf in chronic bronchitis rats.

The study was to evaluate the effect of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf (TAL) on expression of antioxidative mediators by alveolar macrophages (AM) in rats with chronic bronchitis (CB), CB was induced by endotracheal instillation of lipopolysaccharedes (LPS) followed by Bacillus Calmette-Guérin (BCG) injection through caudal vein 1 week later. Treatment groups received TAL at there different doses (50, 150, or 450 mg/kg daily, intragastrically (i.g.)) or dexamethasone (1.2 mg/kg daily i.g.) for 2 weeks, 7 days after LPS injection. AM were then isolated and incubated. Superoxide dismutase (SOD) and methylene dianiline (MDA) levels in AM were measured by commercial kits; meanwhile, heme oxygenase-1 (HO-1) expression and its mRNA expression in AM were detected by immunocytochemistry and RT-PCR, respectively. HO-1 activity of the lung was also detected by a specific biochemistry reaction. The levels of MDA and HO-1 expressed by cultured AM and the HO-1 activity in the lung of the TAL groups were significantly lower than those from the CB group without treatment (p < 0.01 and p < 0.05, respectively), while the SOD levels were increased in a dose-dependent manner by TAL treatment. These results suggest that TAL inhibits HO-1 expression and MDA production and up-regulates SOD expression in AM from CB rats, which might be one of molecular mechanisms of its anti-inflammatory effects in CB rats.

Administration, Oral↗
PubMed2005

Role of the PAR1 receptor 8th helix in signaling: the 7-8-1 receptor activation mechanism.

The protease-activated receptors are tethered ligand G protein-coupled receptors that are activated by proteolytic cleavage of the extracellular domain of the receptor. The archetypic protease-activated receptor PAR1 strongly activates G(q) signaling pathways, but very little is known regarding the mechanism of signal transference between receptor and internally located G protein. The recent x-ray structure of rhodopsin revealed the presence of a highly conserved amphipathic 8th helix that is likely to be physically interposed between receptor and G protein. We found that the analogous 8th helix region of PAR1 was critical for activation of G(q)-dependent signaling. Engineering an 8th helix alpha-aneurysm with a downwards-directed alanine residue markedly interfered with signal transference to G(q). The 8th helix-anchoring cysteine palmitoylation sites were important for the affinity of ligand-dependent G protein coupling but did not affect the maximal signal. A network of H-bond and ionic interactions was found to connect the N-terminal portion of the 8th helix to the nearby NPXXY motif on transmembrane helix 7 and also to the adjacent intracellular loop-1. Disruption of these pairwise interactions caused additive defects in coupling to G protein, indicating that the transmembrane 7-8th helix-i1 loop may move in a coordinated manner to transfer the signal from PAR1 to G protein. This "7-8-1" interaction network was found to be prevalent in G protein-coupled receptors involved in endothelial signaling and angiogenesis.

Amino Acid Sequence↗
PubMed2005

Synthesis of bifunctionalized mesoporous organosilica spheres for high-performance liquid chromatography.

Phenyl-functionalized mesoporous ethane-silicas with spherical morphology were synthesized by one-step co-condensation of phenyltrimethoxysilane (PTMS) and 1,2-bis(trimethoxysily)ethane (BTME) using a triblock copolymer EO(20)PO(70)EO(20) (P123) as template with the aid of a co-surfactant (cetyltrimethylammonium bromide, CTAB) and a co-solvent (ethanol) in acidic medium. Powder X-ray diffraction (XRD), nitrogen sorption measurement and scanning electron microscopy (SEM) show that phenyl-functionalized ethane-silica has wormhole-like mesostructure and perfect spherical morphology. The chemical stability of phenyl-functionalized mesoporous ethane-silica in basic medium is greatly improved owing to the ethane groups bridged in the mesoporous framework. This work also demonstrates that the phenyl-functionalized mesoporous ethane-silica spheres are excellent packing materials for potential application in the reversed-phase high-performance liquid chromatography (HPLC).

Chromatography, High Pressure Liquid↗
PubMed2005

Characterization and expression profile analysis of a new cDNA encoding taxadiene synthase from Taxus media.

A full-length cDNA encoding taxadiene synthase (designated as TmTXS), which catalyzes the first committed step in the Taxol biosynthetic pathway, was isolated from young leaves of Taxus media by rapid amplification of cDNA ends (RACE). The full-length cDNA of TmTXS had a 2586 bp open reading frame (ORF) encoding a protein of 862 amino acid residues. The deduced protein had isoelectric point (pI) of 5.32 and a calculated molecular weight of about 98 kDa, similar to previously cloned diterpene cyclases from other Taxus species such as T. brevifolia and T. chinenisis. Sequence comparison analysis showed that TmTXS had high similarity with other members of terpene synthase family of plant origin. Tissue expression pattern analysis revealed that TmTXS expressed strongly in leaves, weak in stems and no expression could be detected in fruits. This is the first report on the mRNA expression profile of genes encoding key enzymes involved in Taxol biosynthetic pathway in different tissues of Taxus plants. Phylogenetic tree analysis showed that TmTXS had closest relationship with taxadiene synthase from T. baccata followed by those from T. chinenisis and T. brevifolia. Expression profiles revealed by RT-PCR under different chemical elicitor treatments such as methyl jasmonate (MJ), silver nitrate (SN) and ammonium ceric sulphate (ACS) were also compared for the first time, and the results revealed that expression of TmTXS was all induced by the tested three treatments and the induction effect by MJ was the strongest, implying that TmTXS was high elicitor responsive.

Amino Acid Sequence↗
PubMed2005

Preferential inhibition of human phosphodiesterase 4 by ibudilast.

Ibudilast ophthalmic solution exhibited an improved clinical efficacy over cromoglycate in the treatment of allergic conjunctivitis. To further characterize its principal mode of action, the phosphodiesterase (PDE) inhibitory profile of ibudilast has been examined using human recombinant enzymes. Ibudilast, but not the other commonly used anti-allergic ophthalmic solutions including cromoglycate, ketotifen, tranilast and levocabastine, potently inhibits purified human PDE4A, 4B, 4C and 4D with IC50 values at 54, 65, 239 and 166 nM, respectively. Ibudilast effectively blocks lipopolysaccharide (LPS)-induced tumor necrosis factor (TNFalpha, IC50 = 6.2 microM) and N-formyl-Met-Leu-Phe (fMLP)-induced leukotriene (LT) B4 biosynthesis (IC50 = 2.5 microM) in human whole blood, which are 3 and 6-fold more potent than cilomilast, respectively. The attenuated inflammatory and allergic responses from the potent and preferential PDE4 inhibition of ibudilast may have contributed significantly to its beneficial pharmacological responses and distinguishes ibudilast from the other ophthalmic solutions in the treatment of ocular allergy.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2005

Cysteamine increases expression and activity of H+-K+-ATPase of gastric mucosal cells in weaning piglets.

AIM: To determine the in vivo and in vivo effects of cysteamine (CS) on expression and activity of H(+)-K(+)-ATPase of gastric mucosal cells in weaning piglets. METHODS: Eighteen litters of newborn Xinhuai piglets were employed in the in vivo experiment and allocated to control and treatment groups. From 12 d of age (D12), piglets in control group were fed basal diet, while the treatment group received basal diet supplemented with 120 mg/kg CS. Piglets were weaned on D35 in both groups. Six piglets from each group (n = 6) were slaughtered on D28 (one week before weaning), D35 (weaning), D36.5, D38, D42, and D45 (36 h, 72 h, one week and 10 d after weaning), respectively. Semi-quantitative RT-PCR was performed to determine the levels of H(+)-K(+)-ATPase mRNA in gastric mucosa. H(+)-K(+)-ATPase activity in gastric mucosa homogenate was also determined. Gastric mucosal epithelial cells from piglets through primary cultures were used to further elucidate the effect of CS on expression and activity of H(+)-K(+)-ATPase in vivo. Cells were treated for 20 h with 0.001, 0.01, and 0.1 mg/mL of CS (n = 4), respectively. The mRNA expression of H(+)-K(+)-ATPase and somatostatin (SS) as well as the H(+)-K(+)-ATPase activity were determined. RESULTS: in vivo, both mRNA expression and activity of H(+)-K(+)-ATPase in gastric mucosa of control group exhibited a trend to increase from D28 to D45, reaching a peak on D45, but did not show significant age differences. Furthermore, neither the mRNA expression nor the activity of H(+)-K(+)-ATPase was affected significantly by weaning. CS increased the mRNA expression of H(+)-K(+)-ATPase by 73%, 53%, 30% and 39% on D28 (P = 0.014), D35 (P = 0.017), D42 (P = 0.013) and D45 (P = 0.046), respectively. In accordance with the mRNA expression, H(+)-K(+)-ATPase activities were significantly higher in treatment group than in control group on D35 (P = 0.043) and D45 (P = 0.040). In vivo, CS exhibited a dose-dependent effect on mRNA expression and activity of H+-K+-ATPase. Both H(+)-K(+)-ATPase mRNA expression and activity in gastric mucosal epithelial cells were significantly elevated after 20 h of exposure to the moderate (H(+)-K(+)-ATPase expression: P=0.03; H(+)-K(+)-ATPase activity: P = 0.014) and high concentrations (H(+)-K(+)-ATPase expression: P=0.017; H(+)-K(+)-ATPase activity: P = 0.022) of CS. Significant increases in SS mRNA expression were observed to accompany the elevation of H(+)-K(+)-ATPase expression and activity induced by the moderate (P = 0.024) and high concentrations (P = 0.022) of CS. Low concentration of CS exerted no effects either on expression and activity of H(+)-K(+)-ATPase or on SS mRNA expression in cultured gastric mucosal epithelial cells. CONCLUSION: No significant changes are observed in mRNA expression and activity of H(+)-K(+)-ATPase in gastric mucosa of piglets around weaning from D28 to D45. CS increases expression and activity of gastric H(+)-K(+)-ATPase in vivo and in vivo. SS is involved in mediating the effect of CS on gastric H(+)-K(+)-ATPase expression and activity in weaning piglets.

Animals↗
PubMed2005

Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation.

In this paper, we study the morphological transition of bacterial colonies exposed to ultraviolet radiation by modifying the bacteria model proposed by Delprato Our model considers four factors: the lubricant fluid generated by bacterial colonies, a chemotaxis initiated by the ultraviolet radiation, the intensity of the ultraviolet radiation, and the bacteria's two-stage destruction rate with given radiation intensities. Using this modified model, we simulate the ringlike pattern formation of the bacterial colony exposed to uniform ultraviolet radiation. The following is shown. (1) Without the UV radiation the colony forms a disklike pattern and reaches a constant front velocity. (2) After the radiation is switched on, the bacterial population migrates to the edge of the colony and forms a ringlike pattern. As the intensity of the UV radiation is increased the ring forms faster and the outer velocity of the colony decreases. (3) For higher radiation intensities the total population decreases, while for lower intensities the total population increases initially at a small rate and then decreases. (4) After the UV radiation is switched off, the bacterial population grows both outward as well as into the inner region, and the colony's outer front velocity recovers to a constant value. All these results agree well with the experimental observations [Phys. Rev. Lett. 87, 158102 (2001)]. Along with the chemotaxis, we find that lubricant fluid and the two-stage destruction rate are critical to the dynamics of the growth of the bacterial colony when exposed to UV radiation, and these were not previously considered.

Bacillus subtilis↗
PubMed2005

Pre-mental foramen mandibulotomy for resecting tumors of tongue base and parapharyngeal space.

BACKGROUND: Resection of tumors arising from the tongue base and the parapharyngeal space is difficult for exposure and manipulation because of their obscure location. The aim of this study was to evaluate the surgical approach of the pre-mental foramen mandibulotomy for resecting the tumors of tongue base and parapharyngeal space. METHODS: Fifty-one patients with tumors of tongue base and parapharyngeal space were treated using the mandibulotomy approach on the pre-mental foramen. In the present study, this technique was described in detail. The patients were followed up for three months to six years with a mean of 26 months. RESULTS: The tumors of tongue base and parapharyngeal space could be exposed clearly and be resected radically by surgical approach of pre-mental foramen mandibulotomy. The surgical complications were reduced. CONCLUSIONS: Compared to other surgical approaches, such as lateral mandibulotomy, midline mandibulotomy, the suprahyoid parapharyngeal approach, and paramedian mandibulotomy, we found that the pre-mental foramen mandibulotomy is the ideal choice for resecting the tumors of tongue base and parapharyngeal space.

Adolescent↗
PubMed2005

Position of the fluorescent label is a crucial factor determining signal intensity in microarray hybridizations.

A key issue in applications of short oligonucleotide-based microarrays is how to design specific probes with high sensitivity. Some details of the factors affecting microarray hybridization remain unclear, hampering a reliable quantification of target nucleic acids. We have evaluated the effect of the position of the fluorescent label [position of label (POL)] relative to the probe-target duplex on the signal output of oligonucleotide microarrays. End-labelled single-stranded DNA targets of different lengths were used for hybridization with perfect-match oligonucleotide probe sets targeting different positions of the same molecule. Hybridization results illustrated that probes targeting the labelled terminus of the target showed significantly higher signals than probes targeting other regions. This effect was independent of the target gene, the fluorophore and the slide surface chemistry. Comparison of microarray signal patterns of fluorescently end-labelled, fluorescently internally random-labelled and radioactively end-labelled target-DNAs with the same set of oligonucleotide probes identified POL as a critical factor affecting signal intensity rather than binding efficiency. Our observations define a novel determinant for large differences of signal intensities. Application of the POL effect may contribute to better probe design and data interpretation in microarray applications.

DNA, Single-Stranded↗