Biomedical subjects

B Yang

Publications and source records attributed to B Yang.

At least 19 recordsLinked to original sources

PubMed2006

Genetic engineering of Periplaneta fuliginosa densovirus as an improved biopesticide.

The smoky-brown cockroach (Periplaneta fuliginosa) densovirus (PfDNV) has previously shown potential in urban pest control. To improve its efficacy as a biopesticide, the genome of PfDNV was engineered by inserting the insect-specific toxin gene BmKIT1 in the open reading frame encoding the major structural proteins. A green fluorescent protein (GFP) marker was tagged to the BmKIT1 at its C-terminus for in vivo imaging using Confocal laser scanning microscopy (CFSM). Using a virion rescue strategy, the genomes of recombinant and wild-type (wt) PfDNV were then cotransfected in P. fuliginosa nymphs. Reverse transcription PCR (RT-PCR) showed that the inserted BmkIT1 genes were expressed in the P. fuliginosa nymphs 48 h after cotransfection. CFSM and transmission electron microscopy also confirmed the generation of virus particles and expression of BmKIT1-GFP fusion protein in the cotransfected nymphs. The recombinant viruses remained infective to P. fuliginosa nymphs in feeding tests. Using the LT(50) bioassay method, the coninfection of the recombinant and wt PfDNV killed the P. fuliginosa nymphs approximate 32% faster than wt PfDNV only. This is the first report showing the improvement of engineered densovirus for the potential application of biopesticide.

Animals↗

PubMed2006

Panavia F 2.0 bonding to contaminated zirconia ceramic after different cleaning procedures.

OBJECTIVES: The purpose of this laboratory study was to evaluate the influence of different cleaning methods after saliva contamination and after using a silicone disclosing medium on the resin bond strength to zirconia ceramic. The hypothesis was that the resin-ceramic bond strength and its durability are related to the ceramic surface condition. METHODS: Plexiglas tubes filled with composite resin were bonded to air-abraded zirconia ceramic disks using a phosphate monomer containing composite resin. Four surface cleaning methods were used after contaminating the ceramic surface: air abrasion with 50 mum Al(2)O(3) at 2.5 bar pressure for 15s, cleaning with 37% phosphoric acid for 60s once or for 30s twice, or cleaning in 96% isopropanol for 15s. The specimens of the control group were not cleaned after using the silicone disclosing medium. For each combination 16 specimens were bonded in an alignment apparatus. Subgroups of eight bonded specimens were tested for tensile bond strength (TBS) after storage for either 3 or 150 days combined with 37,500 thermal cycles. The statistical analyses were performed with the Kruskal-Wallis test, followed by multiple pair-wise comparisons using the Wilcoxon rank sum test. RESULTS: The mean TBS ranged from 6.6 to 49.9 MPa after 3 days and from 0 to 19.8 MPa after 150 days. Air abrasion of the ceramic surface provided statistically significantly higher bond strengths than the other cleaning methods after 3 and 150 days. Alcohol cleaning of the ceramic did not provide durable bond strengths over time. SIGNIFICANCE: Ceramic cleaning methods after try-in procedures have a significant influence on the resin-ceramic bond strength. Air abrasion of contaminated zirconia ceramic is the most effective.

2-Propanol↗

PubMed2006

Placental and membrane aquaporin water channels: correlation with amniotic fluid volume and composition.

OBJECTIVES: To assess the role of aquaporins (AQPs) in the regulation of amniotic fluid (AF) volume, we determined AF volume and composition and placental and fetal membrane AQP expression throughout the second half of murine gestation. METHODS: Pregnant CD1 mice were sacrificed at e10-19 and AF volume and composition determined. Placenta and fetal membranes were screened for AQP gene expression. AQP gene expression was quantified by real-time RT PCR and protein location determined by immunohistochemistry. Changes in AF volume were correlated with AQP expression. RESULTS: Both membranes and placenta demonstrated expression of AQP1, -3, -8 and -9. Advancing gestation was associated with increased AF volume from e10 to e16, with a marked decrease in AF volume from e16 to e19. By immunohistochemistry, AQP1 was localized to placental vessels and AQP3 to trophoblast. AF volume was negatively correlated with fetal membrane AQP1 and placental AQP1 and AQP9 expression, and positively correlated with placental AQP3 expression. CONCLUSION: Changes in AQPs with advancing gestation, and their correlation with AF volume, suggest a role in mediating placental and membrane water flow and ultimately AF volume. AQP1 appears to regulate fetal membrane water flow, and AQP3 is a likely candidate for the regulation of placental water flow.

Amniotic Fluid↗

PubMed2006

MCP-1 enhances excitability of nociceptive neurons in chronically compressed dorsal root ganglia.

Previous experimental results from our laboratory demonstrated that monocyte chemoattractant protein-1 (MCP-1) depolarizes or increases the excitability of nociceptive neurons in the intact dorsal root ganglion (DRG) after a chronic compression of the DRG (CCD), an injury that upregulates neuronal expression of both MCP-1 and mRNA for its receptor CCR2. We presently explore the ionic mechanisms underlying the excitatory effects of MCP-1. MCP-1 (100 nM) was applied, after CCD, to acutely dissociated small DRG neurons with nociceptive properties. Under current clamp, the proportion of neurons depolarized was similar to that previously observed for CCD-treated neurons in the intact ganglion, although the magnitude of depolarization was greater. MCP-1 induced a decrease in rheobase by 44 +/- 10% and some cells became spontaneously active at resting potential. Action potential width at a voltage equal to 10% of the peak height was increased from 4.94 +/- 0.23 to 5.90 +/- 0.47 ms. In voltage clamp, MCP-1 induced an inward current in 27 of 50 neurons held at -60 mV, which increased with concentration over the range of 3 to 300 nM (EC(50) = 45 nM). The MCP-1-induced current was not voltage dependent and had an estimated reversal potential of -27 mV. In addition, MCP-1 inhibited a voltage-dependent, noninactivating outward current, presumably a delayed rectifier type K(+) conductance. We conclude that MCP-1 enhances excitability in CCD neurons by, at least, two mechanisms: 1) activation of a nonvoltage-dependent depolarizing current with characteristics similar to a nonselective cation conductance and 2) inhibition of a voltage-dependent outward current.

Action Potentials↗

PubMed2006

Direct identification of propargyl radical in combustion flames by vacuum ultraviolet photoionization mass spectrometry.

We have developed an effusive laser photodissociation radical source, aiming for the production of vibrationally relaxed radicals. Employing this radical source, we have measured the vacuum ultraviolet (VUV) photoionization efficiency (PIE) spectrum of the propargyl radical (C(3)H(3)) formed by the 193 nm excimer laser photodissociation of propargyl chloride in the energy range of 8.5-9.9 eV using high-resolution (energy bandwidth = 1 meV) multibunch synchrotron radiation. The VUV-PIE spectrum of C(3)H(3) thus obtained is found to exhibit pronounced autoionization features, which are tentatively assigned as members of two vibrational progressions of C(3)H(3) in excited autoionizing Rydberg states. The ionization energy (IE = 8.674 +/- 0.001 eV) of C(3)H(3) determined by a small steplike feature resolved at the photoionization onset of the VUV-PIE spectrum is in excellent agreement with the IE value reported in a previous pulsed field ionization-photoelectron study. We have also calculated the Franck-Condon factors (FCFs) for the photoionization transitions C(3)H(3) (+)(X;nu(i),i = 1-12)<--C(3)H(3)(X). The comparison between the pattern of FCFs and the autoionization peaks resolved in the VUV-PIE spectrum of C(3)H(3) points to the conclusion that the resonance-enhanced autoionization mechanism is most likely responsible for the observation of pronounced autoionization features. We also present here the VUV-PIE spectra for the mass 39 ions observed in the VUV synchrotron-based photoionization mass spectrometric sampling of several premixed flames. The excellent agreement of the IE value and the pattern of autoionizing features of the VUV-PIE spectra observed in the photodissociation and flames studies has provided an unambiguous identification of the propargyl radical as an important intermediate in the premixed combustion flames. The discrepancy found between the PIE spectra obtained in flames and photodissociation at energies above the IE(C(3)H(3)) suggests that the PIE spectra obtained in flames might have contributions from the photoionization of vibrationally excited C(3)H(3) and/or the dissociative photoionization processes involving larger hydrocarbon species formed in flames.

Journal Article↗

PubMed2006

Long-term efficiency and stability of wetlands for treating wastewater of a lead/zinc mine and the concurrent ecosystem development.

A constructed wetland system in Guangdong Province, South of China has been used for treating Pb/Zn mine discharge since 1985. The performance in the purification of the mine discharge and the concurrent ecosystem development within the system during the period of 1985-2000 has been studied. The untreated wastewater contained rather high concentrations of cadmium (Cd) (0.05 mg L(-1)), lead (Pb) (11.5 mg L(-1)), and zinc (Zn) (14.5 mg L(-1)), which greatly exceed the upper limits for industrial wastewater discharge in China. The constructed wetland system effectively removed Cd by 94.00%, Pb by 99.04%, Zn by 97.30%, and total suspended solids (TSS) by 98.95% from the mine discharge over a long period (over 16 years) leading to significant improvement in water quality; it was also found that there were no significantly annual or monthly variations in pH values, As, Cd, Hg, Pb, and Zn concentrations in water collected from the outlet of the wetland. Moreover, diversity and abundance of living organisms, including protozoan, higher plants, terrestrial animals, and birds, increased gradually. The 16-year monitoring results showed a reciprocal relationship, at a certain extent, between restoration of the wetland ecosystem, in other words, the maturity of the wetland, and the long-term efficiency and stability on purifying heavy metal-contaminated wastewater.

China↗

PubMed2006

Development of a sensitive and rapid liquid chromatography/tandem mass spectrometry method for the determination of apomorphine in canine plasma.

A sensitive, rapid and specific quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of apomorphine (APO) in canine plasma. The analytes were prepared using one-step liquid-liquid extraction, and analyzed on a Waters Symmetry C(18) column interfaced with triple quadrupole tandem mass spectrometer. A mixture of methanol/0.1% formic acid in water (70: 30, v/v) was employed as the isocratic mobile phase. Positive electrospray ionization was utilized as the ionization source. The analyte and clenbuterol (internal standard) were both detected using multiple reaction monitoring (MRM) mode. The limit of detection (LOD) obtained was 0.03 ng/mL. The assay was linear over the concentration range of 0.1-100 ng/mL, and provided good precision (RSD) and good accuracy (RE). The analyte was stable by using antioxidants throughout the whole study. The experimental results show that LC/MS/MS is a rapid and sensitive method to analyze APO in plasma. Finally, the proposed method was successfully applied to a pharmacokinetic study of APO after intranasal administration of 0.5 mg apomorphine to 10 healthy beagle dogs.

Administration, Intranasal↗

PubMed2006

Efficacy assessment of phenobarbital in epilepsy: a large community-based intervention trial in rural China.

BACKGROUND: Many people with epilepsy need not experience further seizures if the diagnosis and treatment are correct. Most epilepsy patients have convulsions, which are usually fairly easy to diagnose. This study tested a model for treatment of people with convulsive forms of epilepsy at primary health-care level in rural areas of China. METHODS: Patients with convulsive epilepsy were identified at primary care level and provided with phenobarbital monotherapy. Local physicians, who were provided with special training, carried out screening, treatment, and follow-up. A local neurologist confirmed the diagnoses. Efficacy was assessed from the percentage reduction in seizure frequency from baseline and the retention of patients on treatment. FINDINGS: The study enrolled 2455 patients. In 68% of patients who completed 12 months' treatment, seizure frequency was decreased by at least 50%, and a third of patients were seizure free. 72% of patients who completed 24 months' treatment had reduction of seizure frequency of at least 50% and a quarter of patients remained seizure free. Probability of retention was 0.84 at 1 year, and 0.76 at 2 years. Medication was well tolerated and reported adverse events were mild; only 32 patients (1%) discontinued medication because of side-effects. INTERPRETATION: This pragmatic study confirmed that this simple protocol was suitable for the treatment of convulsive forms of epilepsy in rural areas of China. Physicians with basic training could treat epilepsy patients with phenobarbital, with beneficial effects for most patients with convulsive seizures. Few cognitive or behavioural adverse events were noted, but formal psychometric testing was not done.

Adolescent↗

PubMed2006

A single-step multiplex PCR for simultaneous detection of white spot syndrome virus and infectious hypodermal and haematopoietic necrosis virus in penaeid shrimp.

White spot syndrome virus (WSSV) and infectious hypodermal and haematopoietic necrosis virus (IHHNV) are the major viral pathogens of penaeid shrimp worldwide (Lightner & Redman 1998). Litopenaeus vannamei was introduced into China from the Americas, and quickly became widely cultured. Following its introduction, both IHHNV and WSSV have become important pathogens of cultured penaeid shrimp and have had a huge impact on the culture industry in China in recent years.

Animals↗

PubMed2006

Efficacy and efficiency of gastric electrical stimulation with short pulses in the treatment of vasopressin-induced emetic responses in dogs.

The aim of this study was to determine the most effective and efficient anti-emetic parameters of short-pulse gastric electrical stimulation (GES) in dogs. Seven female beagle dogs implanted with four pairs of gastric electrodes were studied in eight randomized sessions (saline, vasopressin, and six GES sessions with different parameters). Each session consisted of four 20-min recordings of gastric slow waves and symptoms. In sessions 1 and 2, saline and vasopressin, respectively, were infused during the second 20-min period. The protocol of the other six sessions was the same as session 2 except that GES was continuously applied. It was found that: (1) vasopressin induced gastric dysrhythmia and emetic response (P < 0.01, anova); (2) short-pulse GES with a frequency of 14 or 40 Hz and pulse width of 0.1 or 0.3 ms, but not 0.6 ms was able to reduce symptoms induced by vasopressin; (3) short-pulse GES with a pulse width of 0.3 ms was the most effective in preventing vasopressin-induced symptoms; (4) none of the tested GES methods improved vasopressin-induced gastric dysrhythmia. We conclude that vasopressin induces gastric dysrhythmia and symptoms. Short-pulse GES with a pulse width of 0.3 ms and frequency of 14 Hz is most effective and efficient in preventing vasopressin-induced emetic responses in dogs.

Animals↗

PubMed2006

Increased HO-1 expression and decreased iNOS expression in the hippocampus from adult spontaneously hypertensive rats.

Brain expression of heme oxygenase (HO) and nitric oxide synthase (NOS) in hypertension may participate in the pathogenesis of hypertension-related neuronal disorders, such as vascular dementia. In the present study, expression levels of HO and NOS in spontaneously hypertensive rats (SHR) were investigated using Western immunoblotting assay. Expression level of inducible HO-1 in hippocampus of 4-wk prehypertensive SHR was about twofold of that in age-matched Sprague-Dawley (SD) rats (p < 0.01). In 23-wk SHR with fully developed hypertension, hippocampal HO-1 level was significantly greater than that of age-matched SD rats (p < 0.05), but not different from 4-wk SHR. There was no difference in expression levels of hippocampal HO-2 between SHR and SD rats at different ages. Total enzymatic activity of hippocampal HO was significantly greater in 23-wk SHR than in age-matched SD rats or 4-wk SD/SHR (p < 0.01). Although hippocampal expression of nNOS protein was relatively unchanged, iNOS expression in 23-wk SHR was about fourfold lower than that in age-matched SD rats and 4-wk SD/SHR (p < 0.01). Total enzymatic activity of hippocampal NOS was significantly lower in 23-wk SHR than in age-matched SD rats or 4-wk SD/SHR (p < 0.01). Significantly suppressed Morris water maze performance was found in 23-wk SHR in comparison with age-matched SD rats. Because SHR has been used as a model of vascular dementia and hippocampus is essential for spatial learning and memory, understanding of altered HO/CO and NOS/NO systems in the hippocampus of adult SHR may shed light on the pathogenic development of memory deficits associated with vascular dementia.

Aging↗

PubMed2006

Cloning of pig parotid secretory protein gene upstream promoter and the establishment of a transgenic mouse model expressing bacterial phytase for agricultural phosphorus pollution control.

This study examined the feasibility of using the promoter of the pig parotid secretory protein (PSP) gene for expression of the phytase transgene in mouse models. The pig parotid secretory protein gene is specifically expressed at high levels in the salivary glands. The 10-kb upstream promoter region of the gene necessary for tissue-specific expression has been identified. We have constructed phytase transgenes composed of the appA phytase gene from Escherichia coli driven by the upstream promoter region of the pig PSP gene with a 3' tail of either bovine growth hormone or the pig PSP gene polyadenylation signal. Transgenic mouse models with the construct showed that the upstream region of the pig PSP gene is sufficient for directing the expression of phytase transgenes in the saliva. Expression of salivary phytase reduced fecal phytate by 8.5 and 12.5% in 2 transgenic mouse lines, respectively. These results suggest that the expression of phytase in salivary glands of monogastric animals offers a promising biological approach to relieve the requirement for dietary phosphate supplements and to reduce phosphorus pollution from animal agriculture.

6-Phytase↗

PubMed2005

Nonspherical colloidal crystals fabricated by the thermal pressing of colloidal crystal chips.

Nonspherical colloids and their ordered arrays may be more attractive in applications such as photonic crystals than their spherical counterparts because of their lower symmetries, although such structures are difficult to achieve. In this letter, we describe the fabrication and characterization of colloidal crystals constructed from nonspherical polyhedrons. We fabricated such nonspherical colloidal crystals by pressing spherical polymer colloidal crystal chips at a temperature slightly lower than the glass-transition temperature (T(g)) of these polymer colloids. During this process, the polymer microspheres were distinctively transformed into polyhedrons according to their crystal structures, whereas the long-range order of the 3D lattice was essentially preserved. Because a working temperature lower than T(g) effectively prevented the colloidal crystals from fusing into films, the spherical colloidal crystals were transformed greatly under pressure, which lead to obvious change in the optical properties of colloidal crystals. Besides their special symmetry and optical properties, these nonspherical colloidal crystals can be used as templates for 2D or 3D structures of special symmetry, such as 2D nano-networks. We anticipate that this fabrication technique for nonspherical colloidal crystals can also be extended to nonspherical porous materials.

Journal Article↗

PubMed2005

Pharmacokinetics and metabolism of 1,5-dicaffeoylquinic acid in rats following a single intravenous administration.

1,5-Dicaffeoylquinic acid (1,5-DCQA) is a potentially important HIV-1 integrase inhibitor widely distributed in many plants. To characterize the pharmacokinetic and metabolic properties of 1,5-DCQA in rats following single intravenous administration (160 mg/kg), the plasma concentrations of 1,5-DCQA were measured by high-performance liquid chromatography (HPLC) and the metabolites formed in urine were identified by liquid chromatography-mass spectrometry (LC-MS) in parallel to diode-array detection (DAD). The results showed that the concentrations of 1,5-DCQA in plasma declined rapidly in a biphasic manner with a mean terminal half-life (t(1/2)) of 1.40 h. The mean clearance (CL) and the apparent volume of distribution (Vd(B)) of 1,5-DCQA were 0.44l/h/kg and 0.89l/kg, respectively. A total of 15 metabolites in rat urine were identified, including four isomeric O-mono-methylated (M1-M4), six isomeric O-di-methylated (M5-M10), one isomeric O-mono-methyl-glucuronidated (M11) and four isomeric O-di-methyl-glucuronidated (M12-M15) metabolites. The O-methylation positions of three important metabolites (M1, M2 and M5) were determined (3''-, 3'-, and 3',3''-) by comparing with synthesized standards. These results suggested that the disappearance of 1,5-DCQA from plasma was rapid, and that its quick urinary excretion and extensive metabolism, including methylation and glucuronidation, were two factors causing its rapid elimination from the circulation.

Animals↗

PubMed2005

Targeting of VEGF-mediated angiogenesis to rat myocardium using ultrasonic destruction of microbubbles.

Myocardial angiogenesis mediated by human vascular endothelial growth factor 165 (hVEGF165) cDNA was promoted in rat myocardium using an in vivo-targeted gene delivery system known as ultrasound-targeted microbubble destruction (UTMD). Microbubbles carrying plasmids encoding hVEGF165, or control solutions were infused intravenously during ultrasonic destruction of the microbubbles within the myocardium. Biochemical and histological assessment of gene expression and angiogenesis were performed 5, 10, and 30 days after UTMD. UTMD-treated myocardium contained hVEGF165 protein and mRNA. The myocardium of UTMD-treated animals showed hypercellular foci associated with hVEGF165 expression and endothelial cell markers. Capillary density in UTMD-treated rats increased 18% at 5 days and 33% at 10 days, returning to control levels at 30 days (P<0.0001). Similarly, arteriolar density increased 22% at 5 days, 86% at 10 days, and 31% at 30 days (P<0.0001). Thus, noninvasive delivery of hVEGF165 to rat myocardium by UTMD resulted in significant increases in myocardial capillary and arteriolar density.

Animals↗

PubMed2005

Melanoma inhibitor of apoptosis protein is expressed differentially in melanoma and melanocytic naevus, but similarly in primary and metastatic melanomas.

BACKGROUND: Malignant melanoma is highly resistant to current treatments. The inhibitor of apoptosis protein (IAP) family member, melanoma IAP (ML-IAP), is overexpressed in some melanoma cell lines, rendering them resistant to apoptotic signals. Targeting ML-IAP is a promising approach to treating melanoma. However, the status of ML-IAP expression in human melanoma tissues and the difference in expression between melanoma and melanocytic naevus are not known. AIMS: To investigate these issues. METHODS: ML-IAP expression in 48 archived patient samples (34 melanomas and 14 dermal naevi) was assessed by immunohistochemistry and by in situ hybridisation and reverse transcription polymerase chain reaction (RT-PCR) assays developed for the study. RESULTS: Expression of ML-IAP was detected in 47.6-70.6% (10 of 21 to 24 of 34) of the melanomas, varying with detection methods. The expression rate in melanoma was much higher than that in melanocytic naevus (10.0-21.4%; one of 10 to three of 14). No significant difference was seen between primary and secondary melanomas. ML-IAP expression rates assessed by the three methods were in agreement. CONCLUSIONS: The ML-IAP expression rate in archived melanoma tissues is around 50-70%, with no difference between primary and secondary melanomas. A small number of dermal naevi ( approximately 20%) also expressed ML-IAP.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Polymorphisms of chemokine and chemokine receptor genes in Type 1 diabetes mellitus and its complications.

Cytokines and chemokines have been implicated in the pathogenesis of Type 1 diabetes mellitus (T1DM) and its microvascular complications. Recently, genetic variants of monocyte chemotactic protein-1 (MCP-1), CC-chemokine receptor 2 (CCR2), CC-chemokine receptor 5 (CCR5) genes have been identified. The aim was to investigate whether genetic variants of the MCP-1 G(-2518)A, CCR2B 64I, CCR5 G(59029)A, and CCR5 Delta32 are associated with T1DM and its microvascular complications. Two hundred and sixty patients with T1DM with and without diabetic microvascular complications, and 104 normal controls were recruited for this study. Genotypes of the MCP-1 G(-2518)A, CCR2B 64I, CCR5 G(59029)A, and CCR5 delta32 were performed by polymerase chain reaction followed by digestion with appropriate restriction endonucleases. Frequencies of the MCP-1 A(-2518) allele (74.6% vs. 63.5%, p < 0.003) and A/A genotype (54.5% vs. 34.6%, p < 0.001, Pc = 0.002) were significantly higher in patients with T1DM compared with normal controls. CCR5 G(59029) was slightly increased in the patients with microvascular complications compared with the uncomplicated (21.4% vs. 10%, p < 0.03, Pc = ns). The frequency of haplotype G/G/W was slightly increased in the patients with diabetic complications compared to the uncomplicated (39.6% vs. 28.8%, p < 0.02, Pc = ns). These results suggest that polymorphisms of the MCP-1, CCR2 and CCR5 genes may be associated with T1DM and its complications.

Adolescent↗

PubMed2004

Parity-violating electron deuteron scattering and the proton's neutral weak axial vector form factor.

We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2=0.038 (GeV/c)2. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.

Journal Article↗