Molecularly imprinted polymer microspheres for solid-phase extraction of chloramphenicol residues in foods

Preparation of molecularly imprinted polymer microspheres (MIPMs) for chloramphenicol (CAP) by aqueous suspension polymerization is reported for the first time in this study. The resulting MIPMs had the ability to specifically adsorb CAP, and the molecularly imprinted solid phase extraction (MISPE) based on the MIPMs was shown to be applicable for clean-up and preconcentration of trace CAP in milk and shrimp samples with high recoveries of 92.7% and 84.9%, respectively. Combined with MISPE, the conventional HPLC-UV analysis sensitivity for CAP in foods could be significantly increased.     

Sensitive quantification of rifaximin in human plasma by liquid chromatography-tandem mass spectrometry

A liquid chromatography-mass spectrometry method (LC-MS/MS) for the quantitative determination of rifaximin in human plasma was developed and validated. In the developed procedure, metoprolol was added to human plasma as an internal standard (IS) and acetonitrile was used to precipitate the plasma proteins before LC-MS/MS analysis. Chromatographic separation was obtained on a RESTEK Pinnacle C18 column (50 mm x 2.1mm, 5 microm) with a mobile phase consisted of ammonium acetate solution (15 mM, pH 4.32) as buffer A and methanol as mobile phase B. Quantification was performed in positive mode using multiple reaction monitoring (MRM) of the transitions m/z 786.1-->754.1 for rifaximin and m/z 268.3-->116.1 for the IS. The assay has been validated over the concentration range of 0.5-10 ng/ml (r=0.9992) based on the analysis of 0.2 ml of plasma. The assay accuracy was between 98.2% and 109%. The within-day and between-day precision was better than 3.9% and 8.9% at three concentration levels. The freeze-thaw stability was also investigated and it was found that both rifaximin and the IS were quite stable. This method provides a rapid, sensitive, specific and robust tool for the quantitative determination of rifaximin in human plasma, which is especially useful for the pharmacokinetic study of rifaximin.     

Quantitative determination of trans-polydatin, a natural strong anti-oxidative compound, in rat plasma and cellular environment of a human colon adenocarcinoma cell line for pharmacokinetic studies

A simple, accurate, precise, specific and reproducible high-performance liquid chromatography (HPLC) method was developed for determination of trans-polydatin, a natural strong anti-oxidative compound, in rat plasma and cell suspension. The assay procedure involved simple liquid-liquid extraction, the supernatant liquid was added an equal volume of water to avoid solvent effect. The detection of the analyte peak was achieved by monitoring the eluate using a UV detector set at 303 nm. The analysis used a Hypersil ODS2 C18 column (5 microm, 4.6 mm x 250 mm) and methanol/distilled water as the mobile phase (flow rate=1 mL/min). A total analytical run was achieved within 6.0 min and calibration curve was linear over a wide concentration range of 0.25-40 microg/mL for plasma sample and 1.0-500 microM for cell suspension, the coefficients of correlation were 0.9997 and 0.9999 or better, respectively. There was 80.7+/-7.86%, 96.8+/-3.20% and 102.7+/-9.72% recovery from 0.5, 10, and 40 microg/mL plasma samples, respectively. Intra- and inter-batch accuracy and precision were acceptable for the both matrices. The RSD of intra- and inter-day assay variations were all less than 10%. Both analyte and IS were stable in the battery of stability studies, freeze-thaw cycles. The described assay method was applied to pharmacokinetic studies in rats and a human colon adenocarcinoma cell line (Caco-2) successfully. The application of the assay to determine the pharmacokinetic is described.     

Membrane subproteomic analysis of Mycobacterium bovis bacillus Calmette-Guérin

Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine has been known for a long time to prevent tuberculosis (TB) worldwide since 1921. Nonetheless, we know little about BCG membrane proteome. In the present study, we utilized alkaline incubation and Triton X-114-based methods to enrich BCG membrane proteins and subsequently digested them using proteolytic enzyme. The recovered peptides were further separated by 2-D LC and identified by ESI-MS/MS. As a result, total 474 proteins were identified, including 78 integral membrane proteins (IMPs). Notably, 18 BCG IMPs were described for the first time in mycobacterium. Further analysis of the 78 IMPs indicated that the theoretical molecular mass distribution of them ranged from 8.06 to 167.86 kDa and pI scores ranged from 4.40 to 11.60. Functional classification revealed that a large proportion of the identified IMPs (67.9%, 53 out of 78) were involved in cell wall and cell processes functional group. In conclusion, here we reported a comprehensive profile of the BCG membrane subproteome. The present investigation may allow the identification of some valuable vaccine and drug target candidates and thus provide basement for future designing of preventive, diagnostic, and therapeutic strategies against TB.     

High prevalence of NTDs in Shanxi Province: a combined epidemiological approach

BACKGROUND: Shanxi Province has historically reported a high prevalence of NTDs. In order to establish baseline rates for NTDs and discuss the risk factors associated with sociodemographic, maternal characteristics, and geographic factors, we performed the present study using an approach combining population and hospital-based methodologies. METHODS: We used chi(2) and Fisher's exact tests to evaluate variation in the prevalence by selected covariates and computed crude ORs and 95% CIs. Adjusted odds ratios (AORs) were performed using logistic regression with all the covariates included in the model. RESULTS: The overall NTD prevalence during the 3 year study period was 199.38 per 10,000 births, with a higher NTD prevalence clustered in 46 villages within this geographic area. However, no statistical significance was found between NTD prevalence and the elevation of the villages or their distance from coal plants. AORs revealed women aged 20 and above had a lower risk of NTDs compared to those younger than 20 (AOR range 0.4-0.5). A higher risk of NTDs was observed among female infants (AOR 1.50; 95% CI: 1.04-2.17), women with four or more previous births (AOR 2.80; 95% CI: 1.20-6.52), and a previous history of birth defects (AOR 3.23; 95% CI: 1.46-7.12). CONCLUSIONS: This study has documented a high prevalence of NTDs in Shanxi. Similar variations to other reports were found in the risk of NTDs by maternal demographic characteristics and a clustering of NTDs in certain villages that require further exploration.     

In situ proteolysis for protein crystallization and structure determination

We tested the general applicability of in situ proteolysis to form protein crystals suitable for structure determination by adding a protease (chymotrypsin or trypsin) digestion step to crystallization trials of 55 bacterial and 14 human proteins that had proven recalcitrant to our best efforts at crystallization or structure determination. This is a work in progress; so far we determined structures of 9 bacterial proteins and the human aminoimidazole ribonucleotide synthetase (AIRS) domain.     

Identification and characterization of a functional Candida albicans homolog of the Saccharomyces cerevisiae TCO89 gene

As one of the components of target of rapamycin complex 1 (TORC1), ScTco89p is involved in rapamycin sensitivity and cellular integrity in Saccharomyces cerevisiae. Here we provide evidence showing that deletion of ScTCO89 causes yeast cells to be hypersensitive to salt stress in a high osmolarity glycerol pathway-independent fashion. In addition, we have identified and characterized a functional Candida albicans homolog (CaTCO89) of ScTCO89, which encodes a protein of 708 amino acids that shows overall 15% identity with ScTco89p at the amino acid level. However, CaTCO89 could complement the functions of ScTCO89 in rapamycin sensitivity, salt tolerance, and cellular integrity. Candida albicans cells disrupted for CaTCO89 are also sensitive to rapamycin and lithium salt, but not susceptible to challenges to cellular integrity.     

Endocytic protein Pal1 regulates appressorium formation and is required for full virulence of Magnaporthe oryzae

Endocytosis plays key roles during infection of plant-pathogenic fungi, but its regulatory mechanisms are still largely unknown. Here, we identified a putative endocytosis-related gene, PAL1, which was highly expressed in appressorium of Magnaporthe oryzae, and was found to be important for appressorium formation and maturation. Deletion of PAL1 significantly reduced the virulence of M. oryzae due to defects in appressorial penetration and invasive growth in host cells. The Pal1 protein interacted and colocalized with the endocytosis protein Sla1, suggesting it is involved in endocytosis. The Δpal1 mutant was significantly reduced in appressorium formation, which was recovered by adding exogenous cAMP and 3-isobutyl-1-methylxanthine (IBMX). Moreover, the phosphorylation level of Pmk1 in Δpal1 was also reduced, suggesting Pal1 functions upstream of both the cAMP and Pmk1 signalling pathways. As a consequence, the utilization of glycogen and lipid, appressorial autophagy, actin ring formation, localization of septin proteins, as well as turgor accumulation were all affected in the Δpal1 mutant. Taken together, Pal1 regulates cAMP and the Pmk1 signalling pathway for appressorium formation and maturation to facilitate infection of M. oryzae.     

Ultra-Broadband Electromagnetically Induced Transparency in Metamaterial Based on Conductive Coupling

Plasmonics - This paper proposes a structure composed of a horizontal metal strip resonator (SR) and four C-shaped ring resonators (CRR) to obtain a broadband electromagnetic induction transparency...