Rapamycin Exacerbates Staphylococcus aureus Pneumonia by Inhibiting mTOR-RPS6 in Macrophages

Purpose

This study aimed to explore the effect of Rapamycin (Rapa) in Staphylococcus aureus (S. aureus) pneumonia and clarify its possible mechanism.

Methods

We investigated the effects of Rapa on S. aureus pneumonia in mouse models and in macrophages cultured in vitro. Two possible mechanisms were investigated: the mTOR-RPS6 pathway phosphorylation and phagocytosis. Furthermore, for the mechanism verification in vivo, mice with specific Mtor knockout in myeloid cells were constructed for pneumonia models.

Results

Rapa exacerbated S. aureus pneumonia in mouse models, promoting chemokines secretion and inflammatory cells infiltration in lung. In vitro, Rapa upregulated the secretion of chemokines and cytokines in macrophages induced by S. aureus. Mechanistically, the mTOR-ribosomal protein S6 (RPS6) pathway in macrophages was phosphorylated in response to S. aureus infection, and the inhibition of RPS6 phosphorylation upregulated the inflammation level. However, Rapa did not increase the phagocytic activity. Accordingly, mice with specific Mtor knockout in myeloid cells experienced more severe S. aureus pneumonia.

Conclusion

Rapa exacerbates S. aureus pneumonia by increasing the inflammatory levels of macrophages. Inhibition of mTOR-RPS6 pathway upregulates the expression of cytokines and chemokines in macrophages, thus increases inflammatory cells infiltration and exacerbates tissue damage.

[Analysis of time for diagnosis of nontuberculous mycobacterial lung disease and its associated factors in a tuberculosis-designated hospital in Shanghai]

Objective: To investigate the pathogenic characteristics, bacteriological diagnosis time and its associated factors among patients with nontuberculous mycobacterial (NTM) lung disease in a large tuberculosis-designated hospital in Shanghai from 2020 to 2021, in order to improve diagnosis efficiency and formulate precision treatment. Methods: On the basis of the Tuberculosis Database in Shanghai Pulmonary Hospital, NTM patients diagnosed by the Department of Tuberculosis between January 2020 and December 2021 were screened. Demographic, clinical and bacterial information were retrospectively collected. Chi-square test, paired-sample nonparametric test and logistic regression model were used to analyze the factors associated with the diagnosis time of NTM lung disease. Results: A total of 294 patients with bacteriologically confirmed NTM lung disease were included in this study, 147 males and 147 females with a median age of 61(46, 69) years. Of them, 227 (77.2%) patients had comorbidity of bronchiectasis. Species identification results showed that Mycobacterium Avium-Intracellulare Complex was the main pathogen of NTM lung disease (56.1%), followed by Mycobacterium kansasii (19.0%) and Mycobacterium abscessus (15.3%). Species such as Mycobacterium xenopi and Mycobacterium malmoense were rarely identified, accounting for a total proportion of only 3.1%. Positive culture rates for sputum, bronchoalveolar lavage fluid and puncture fluid were 87.4%, 80.3% and 61.5%, respectively. Paired-sample analysis showed that the positive rate of sputum culture was significantly higher than that of smear microscopy (87.1% vs. 48.4%, P<0.01), while no statistical difference was observed between sputum and bronchoalveolar lavage fluid on positive culture rate (78.7% vs. 77.3%, P>0.05). Patients with cough or expectoration were observed with 4.04-fold (95%CI 1.80-9.05) or 2.95-fold (95%CI 1.34-6.52) higher probability of positive sputum culture, compared to those without. Regarding bronchoalveolar lavage fluid, female or patients with bronchiectasis had a 2.82-fold (95%CI 1.16-6.88) or 2.38-fold (95%CI 1.01-5.63) higher probability to achieve a positive culture. The median time to diagnosis of NTM lung disease was 32 (interquartile range: 26-42) days. The results of multivariable analysis showed that patients with symptom of expectoration (aOR=0.48, 95%CI 0.29-0.80) needed a shorter diagnosis time in comparison with patients without expectoration. With Mycobacterium Avium-Intracellulare Complex as a reference, lung disease caused by Mycobacterium abscessus needed shorter diagnosis time (aOR=0.43, 95%CI 0.21-0.88), whereas those caused by rare NTM species were observed to require a longer diagnosis time (aOR=8.31, 95%CI 1.01-68.6). Conclusion: The main pathogen causing NTM lung disease in Shanghai was Mycobacterium Avium-Intracellulare Complex. Sex, clinical symptoms and bronchiectasis had an impact on the positive rate of mycobacterial culture. The majority of patients in study hospital were timely diagnosed. Clinical symptoms and NTM species were associated with the bacteriological diagnosis time of NTM lung disease.

Two Strongly Truthful Mechanisms for Three Heterogeneous Agents Answering One Question

Peer prediction mechanisms incentivize self-interested agents to truthfully report their signals even in the absence of verification, by comparing agents’ reports with their peers. We propose two new mechanisms, Source and Target Differential Peer Prediction, and prove very strong guarantees for a very general setting.

Our Differential Peer Prediction mechanisms are strongly truthful : Truth-telling is a strict Bayesian Nash equilibrium. Also, truth-telling pays strictly higher than any other equilibria, excluding permutation equilibria, which pays the same amount as truth-telling. The guarantees hold for asymmetric priors among agents which the mechanisms need not know ( detail-free ) in the single question setting . Moreover, they only require three agents , each of which submits a single item report : two report their signals (answers), and the other reports her forecast (prediction of one of the another agent’s reports). Our proof technique is straightforward, conceptually motivated, and turns on the logarithmic scoring rule’s special properties.

Moreover, we can recast the Bayesian Truth Serum mechanism [20] into our framework. We can also extend our results to the setting of continuous signals with a slightly weaker guarantee on the optimality of the truthful equilibrium.

Characteristics and long-term ablation outcomes of supraventricular arrhythmias in hypertrophic cardiomyopathy: a 10-year, single-center experience

Background

A variety of supraventricular arrhythmias (SVAs) may occur in patients with hypertrophic cardiomyopathy (HCM). The characteristics and long-term ablation outcomes of different types of SVAs in HCM have not been comprehensively investigated.

Methods

We retrospectively enrolled 101 consecutive symptomatic HCM patients with suspected arrhythmia from May 2010 to October 2020. The clinical features and ablation outcomes of patients with SVAs were further analyzed.

Results

Seventy-eight patients had SVAs, consisting of 50 (64.1%) atrial fibrillation (AF), 16 (20.5%) atrial flutter (AFL), 15 (19.2%) atrioventricular reentrant tachycardia (AVRT), 11 (14.1%) atrial arrhythmia (AT), and 3 (3.8%) atrioventricular nodal reentrant tachycardia (AVNRT). Thirty-four patients underwent catheter ablation including 14 for AF, 9 for AVRT, 6 for AFL, 3 for AVNRT, 1 for both AF and AFL, and 1 for both AF and AVRT. They were followed up for a median (interquartile range) of 58.5 (82.9) months. There were no recurrences for patients with non-AF SVAs. For patients with AF, the 1- and 7-year AF-free survival were 87.5% and 49.5%, respectively. A ROC analysis revealed that a greater left ventricular end-diastolic dimension (LVEDD) was associated with higher recurrence of AF with an optimum cutoff value of 47mm (c-statistic = 0.91, p=0.011, sensitivity = 1.00, specificity = 0.82). In Kaplan-Meier analysis, patients with LVEDD ≥47mm had worse AF-free survival (log-rank p=0.014).

Conclusions

AF is the most common SVA in HCM, with AFL, AVRT, AT, and AVNRT ranking the second to the last according to the prevalence. The long-term catheter ablation outcome for non-AF SVAs in HCM is satisfying. A greater LVEDD predicts AF recurrence after catheter ablation in patients with HCM.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): National Natural Science Foundation of China Figure 1Figure 2

Polyketide Synthase Gene Expression in Relation to Chloromonilicin and Melanin Production in Monilinia fructicola

Monilinia fructicola is a fungal pathogen of worldwide significance that causes brown rot of stone fruits. There are only few reports related to the production of biologically active polyketides by this pathogen. In this study, we examined an atypical M. fructicola strain TW5-4 that shows strong antimicrobial activity against various plant pathogens. TW5-4 also displays sparse growth in culture, low virulence, and higher levels of melanin compared with its albino mutant, TW5-4WM, and a wild-type strain Mf13-81. Antifungal compounds were extracted from TW5-4 and purified by thin-layer chromatography following visualization with an on-the-chromatogram inhibition assay. The principal antifungal compound was identified by linear ion trap mass spectrometry, high-resolution electro-spray ionization mass spectrometry, and proton nuclear magnetic resonance analyses as the polyketide chloromonilicin. Multiple M. fructicola polyketide synthase (PKS) sequences were then cloned by degenerate PCR and inverse PCR. Sequence analyses support presence of a 10-member PKS gene family in the M. fructicola genome. Analyses of PKS gene expression found no strong correlation between chloromonilicin production in culture and transcript levels of any of the PKS gene family members in mycelium of strains TW5-4, TW5-4WM, and Mf13-81. However, MfPKS12, a homolog of BcPKS12 involved in biosynthesis of 1,8-dihydroxynaphthalene (DHN)-melanin in Botrytis cinerea, was strongly expressed in mycelia of TW5-4 and Mf13-81. An MfPKS12-silenced mutant accumulated significantly less melanin in mycelia, had lower resistance to polyethylene glycol-induced osmotic stress, and displayed reduced virulence on nectarine fruit. The results suggest that DHN-melanin is required for tolerance to osmotic stress and full virulence in M. fructicola.

[Advance and review: miniscrew-assisted rapid palatal expansion]

Rapid palatal expansion (RPE) is commonly used to correct transverse maxillary deficiencies and recognized as a reliable orthopedic procedure in children and adolescents. For adults, however, conventional RPE has been considered rarely successful and can produce undesirable dental effects. Along with the development of digital techniques and mini-implant anchorage, a novel method called miniscrew-assisted RPE (MARPE) has become available for the treatment of maxillary transverse deficiency in older patients recently. In this article, the biomechanical principles and indications of MARPE, the advances in device design, the clinical effects, the matters needing attention and limitations of this method, and the stability after expansion are discussed.

miR-483 is down-regulated in gastric cancer and suppresses cell proliferation, invasion and protein O-GlcNAcylation by targeting OGT

MicroRNAs (miRNAs) are involved in the gastric carcinogenesis and progression. Here, we confirmed that miR-483 was frequently decreased in gastric cancer patients. The expression levels of miR-483 were negatively correlated with tumor stage, node metastasis and stromal invasion. Log-rank tests demonstrated that low expression of miR-483 was strongly correlated with poor overall survival in patients with gastric cancer. Moreover, ectopic expression of miR-483 remarkably suppressed gastric cancer cell proliferation by enhancing cell apoptosis and significantly inhibited the invasion of gastric cancer cells, while low expression of miR-483 exhibited the opposite effect. Bioinformatics analysis revealed that OGT was a potential target of miR-483, and miR-483 inhibited the expression level of OGT mRNA by direct binding to its 3'-untranslated region (3'UTR). Expression of miR-483 was negatively correlated with OGT in gastric cancer tissues. In addition, modulation of miR-483 expression could affect the global cellular protein O-GlcNAcylation in gastric cancer cells. Furthermore, silencing of OGT counteracted the effects of miR-483 repression, while its overexpression reversed tumor inhibitory effects of miR-483. In conclusion, our study revealed that miR-483 functions as a tumor suppressor by inhibiting proliferation, invasion and protein O-GlcNAcylation of gastric cancer via targeting OGT, and that miR-483 may serve as prognostic or therapeutic target for gastric cancer.

[Pathogen spectrum in enteroviral infections among children in Beijing from 2010 to 2016]

Objective: To understand the epidemiological and etiological characteristics of enterovirus (EV)-associated diseases among children in Beijing from 2010 to 2016. Methods: This was a repeated cross-sectional study. The throat swabs were collected from children with probable EV-associated diseases at the Children' s Hospital Affiliated to Capital Institute of Pediatrics from 2010 to 2016. The samples were sent for pan-EV, enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) detection by real-time fluorescence reverse transcription polymerase chain reaction (RT-PCR) . The viral types of non-EV-A71 and non-CV-A16 EV-positive samples were identified using modified RT-PCR and sequencing with CV-A6, EV-A/B group and 5 'UTR universal primers. The constituent ratios of the prevalence of different EV types in different age and gender groups were compared. Results: Of the 2 703 throat swabs, 1 992 (73.7%) samples were positive for EV, including EV-A71 (19.1%, 516/2 703), CV-A16 (24.3%, 658/2 703), CV-A6 (22.2%, 600/2 703), CV-A10 (4.5%, 122/2 703) and other types of EV (3.5%, 95/2 703). There was 1 case of EV-A71 and CV-A16 co-infection. The positive detection rate of EV-A group (excluding EV-A71, CV-A16, CV-A6 and CV-A10) increased from 11.3% (7/62) to 95.2% (59/62) after using the modified VP1-specific primers and PCR amplification conditions. During the period between 2010 and 2012, CV-A16 and EV-A71 predominated in EV-positive samples. However, CV-A6 accounted for 60.7% (68/112) in 2013, much higher than CV-A16 (23.2%, 26/112) and EV-A71 (12.5%, 14/112). In 2014, EVs were mainly of CV-A16 and EV-A71, but CV-A6 was the predominant type in 2015 (68.2%, 232/340) and in 2016 (38.6%, 151/391). The epidemic season of EVs was mostly from April to August, but CV-A6 showed a small epidemic peak from October to November. The male-to-female ratio of EV-positive patients was 1.50∶1, and EV-associated diseases mostly occurred in children under 5 years of age. Younger children were more susceptible to CV-A6 than to EV-A71 and CV-A16. Conclusions: From 2010 to 2016, there was a significant change in the spectrum of EVs in children with EV-associated diseases in Beijing. Since 2013, non-EV-A71 and non-CV-A16 increased, and CV-A6 gradually became one of the major pathogens of EV-associated diseases. The modified PCR primers and amplification conditions can effectively improve the reliability of test results.

[Application of mind mapping in the teaching of oral and maxillofacial development]

Oral and maxillofacial development is the course that the oral students first learn, and their mastery directly influences the study of other courses that follow. The application of mind mapping in the teaching of the development of oral maxillofacial region can make the temporal and spatial features of oral and maxillofacial development in the form of visual presentation, help students build development mode of thinking, stimulate students' interest in learning, improve the quality of teaching of oral histopathology, and promote the new teaching concept in oral pathology teaching.

[Effect of occupational exposure on job burnout in nurses]

Objective: To investigate the effect of occupational exposure on job burnout in nurses, and to analyze the mediating effect of negative emotion between occupational exposure and job burnout and the regulatory effect of supervisor support on occupational exposure and negative emotion. Methods: From September to December, 2015, simple random sampling was used to select 543 nurses from six tertiary hospitals in Zhejiang Province, China. The questionnaires consisted of occupational exposure risk questionnaire, negative emotion questionnaire, supervisor support questionnaire, and job burnout questionnaire. Results: The total score of occupational exposure risk in nurses was 11.43±7.19; the score of emotional exhaustion was 3.19±1.24, the score of low sense of personal accomplishment was 3.02±1.21, and the score of sense of working indifference was 2.24±1.06. There were significant differences in occupational exposure score between nurses with different sexes (t=2.61, P<0.01) and working years (F=4.49, P<0.01) . There were significant differences in the scores of emotional exhaustion and low sense of personal accomplishment in nurses with different sexes (t=5.25, P<0.001) and working years (t=-3.48, P<0.01) . Occupational exposure had positive effects on negative emotion (β=0.41, P<0.05) , emotional exhaustion (β=0.47, P<0.05) , sense of working indifference (β=0.42, P<0.05) , and low sense of personal accomplishment (β=0.17, P<0.05) . Negative emotion had a partial mediating effect between occupational exposure and emotional exhaustion (total effect size 30.5%, P<0.05) and between occupational exposure and sense of working indifference (total effect size 37.1%, P<0.05) . Negative emotion had a complete mediating effect between occupational exposure and low sense of personal accomplishment (β=0.08, P>0.05) . Supervisor support negatively regulate the effects of occupational exposure and negative emotion (F=21.73, P<0.001) . Conclusion: In nurses, occupational exposure has a direct positive effect on job burnout and indirectly influences job burnout via negative emotion. Supervisor support can reduce the negative impact of occupational exposure on negative emotion.

Expression of Five Endopolygalacturonase Genes and Demonstration that MfPG1 Overexpression Diminishes Virulence in the Brown Rot Pathogen Monilinia fructicola

Monilinia fructicola is a devastating pathogen on stone fruits, causing blossom blight and fruit rot. Little is known about pathogenic mechanisms in M. fructicola and related Monilinia species. In this study, five endopolygalacturonase (endo-PG) genes were cloned and functionally characterized in M. fructicola. Quantitative reverse-transcriptase PCR (qRT-PCR) revealed that the five MfPG genes are differentially expressed during pathogenesis and in culture under various pH regimes and carbon and nitrogen sources. MfPG1 encodes the major endo-PG and is expressed to significantly higher levels compared to the other four MfPGs in culture and in planta. MfPG1 function during pathogenesis was evaluated by examining the disease phenotypes and gene expression patterns in M. fructicola MfPG1-overexpressing strains and in strains carrying the β-glucuronidase (GUS) reporter gene fused with MfPG1 (MfPG1-GUS). The MFPG1-GUS reporter was expressed in situ in conidia and hyphae following inoculation of flower petals, and qRT-PCR analysis confirmed MfPG1 expression during pathogenesis. MfPG1-overexpressing strains produced smaller lesions and higher levels of reactive oxygen species (ROS) on the petals of peach and rose flowers than the wild-type strain, suggesting that MfPG1 affecting fungal virulence might be in part resulted from the increase of ROS in the Prunus–M. fructicola interactions.

First Report of Pindo Palm Heart Rot Caused by Ceratocystis paradoxa in China

On January 12th, 2012, a novel disease with an incidence of 50% was discovered in Pindo palm Butia capitata (Mart.) Becc from the Coconut Grant View Garden (19°33.137' N, 110°47.482' E) located in Wenchang, Hainan Province. Diseased leaflets at the base of the rotted heart leaves had reddish brown lesions; when the infection progressed, the leaves turned yellow and became blighted from the inner to the outer part of the crown. Once the growing point was destroyed, the entire tree ultimately died. Tissues from the edges of lesions from diseased leaflet samples were placed onto potato dextrose agar (PDA) and incubated at 25°C for 3 days. The color of colonies of five isolates obtained turned from white to black in 48 h. The optimum temperature for mycelium growth was from 20 to 30°C, and no growth occurred at temperatures higher than 40°C or lower than 5°C (n = 5). The cylindrical colorless to pale brown conidia were 7.5 to 17.5 μm long × 5.0 to 7.5 μm wide (n = 100); oval black chlamydospores were 12.5 to 22.5 × 7.5 to 15.0 μm (n = 100). The sequence (497 bp) of the internal transcribed spacer (ITS) region of the representative isolate BX3 (China Center for Type Culture Collection No. CCTCC AF2014002) was amplified using primer pair ITS1/ITS4 (GenBank Accession No. KF939052) and shared 99% sequence identity with Ceratocystis paradoxa strain xie331-4 (JQ039332). Based upon these biological characteristics and ITS sequence, this pathogen was identified as C. paradoxa (Dade) C. Moreau (anamorph Thielaviopsis paradoxa (de Seynes) Höhn.) (3). Pathogenicity tests were conducted on 8-cm-long sections of young leaflets excised from a 12-year-old pindo palm tree. One side of the midrib of 10 sections was wounded with a sterilized scalpel at the center and the other side was non-wounded, then a PDA plug (4 to 6 × 4 to 6 mm) from the edge of an actively growing colony of BX3 incubated for 3 days were inoculated onto each wounded or non-wounded site. As controls, plain PDA plugs were placed on wounded and non-wounded spots of another 10 sections following the above procedure. Pathogenicity was tested twice. Each inoculated section was then put into a 9-cm petri dish in which two filter papers (Φ = 9 cm) were placed and 8 ml of sterile water were added to maintain high humidity, and then all dishes were placed in a dark incubator at 25°C. After 5 days, typical symptoms developed only on the wounded points inoculated with mycelium plugs. C. paradoxa was re-isolated from the margins of the expanding lesions. C. paradoxa causing fruit rot of B. capitata was reported in Uruguay (2), but to our knowledge, there are no previous reports of this species in China or infecting leaves of B. capitata worldwide (1). We report here a new Ceratocystis disease on B. capitata, and it was named as pindo palm heart rot based on its symptoms. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , Feb 21, 2014. (2) V. Gepp et al. New Dis. Rep. 27:12, 2013. (3) F. Y. Yu et al. Plant Dis. 96:290, 2012.

First Report of Burkholderia andropogonis Causing Bacterial Leaf Spot of Betel Palm in Hainan Province, China

In May 2009, a severe bacterial disease of arecanut (Areca catechu L.) with an incidence of 100% was observed in a plantation of about 8,400 plants in Wenchang City, Hainan Province, China (19°47.171' N, 110°54.335' E). Symptoms consisted of small circular to elongated brown lesions, ranging from 1 to 105 mm in length and 1 to 21 mm in width, surrounded by yellow halos. White colonies, without fluorescent or diffusible pigments, were consistently recovered on King's B Medium plates from lesions surface-sterilized in 70% ethyl alcohol for 1 min. All isolates were gram-negative and each had a single, polar, sheathed flagellum. Isolates were identified as a Burkholderia sp. based on physiological and biochemical tests: oxidase and catalase positive, negative for arginine dihydrolase, gelatin hydrolysis and starch hydrolysis, and negative for acid production from levan (1,3). Sequences (approx. 1,400 bp each) of the 16S rRNA gene amplified from four isolates using primer pair 27F/1492R (2) (GenBank Accession Nos. JX415481, JX415479, JX415482, and JX415483) shared 99% sequence identity with that of Burkholderia andropogonis strain 6369 (DQ786951). Representative isolates Y11 (China General Microbiological Culture Collection Center No. CGMCC 1.12337), Y30 (CGMCC 1.12338), W15, and W20 were compared with B. andropogonis strain NCPPB No. 1012 and all caused a hypersensitive reaction on leaves of Nicotiana benthamiana. Isolate pathogenicity was tested twice with a total of three replications per isolate. Two young leaves each of 2-year-old arecanut plants were infiltrated with a bacterial suspension of 10⁸ CFU/ml, then covered individually with plastic bags for 48 h, and incubated at 100% relative humidity with 16 h of daylight at 25°C by day and 8 h of darkness at 20°C by night. After 7 days, small water-soaked spots with yellow halos were observed and 60 days after inoculation, lesions developed similar to those caused by B. andropogonis in the field. Koch's postulates were fulfilled by reisolating bacteria from typical lesions on inoculated plants. These bacteria were identical to inoculated strains in colony morphology and sequences of the 16S ribosomal RNA gene. To our knowledge, this is the first report of B. andropogonis infection on betel in Hainan Province, mainland China. This disease was first reported in Taiwan, a province of China. Conditions of high humidity and high temperature support disease outbreaks and infection can result in severe economic losses. In 2012, this disease also appeared on a number of plantations located in other counties. As betel is, economically, the second most important crop in Hainan Province, measures should be required to control this disease, especially in typhoon seasons. References: (1) S. H. Hseu et al. Plant Pathol. Bull. 16:131, 2007. (2) D. J. Lane. In: E. Stackebrandt, et al. Nucleic acid techniques in bacterial systematics. John Wiley & Sons, Chichester, United Kingdom, pp. 115-175, 1991. (3) X. Li and S. H. De Boer. Plant Dis. 89:1132. 2005.

Color, dye and DOC removal, and acid generation during fenton oxidation of dyes

The removal of color, dye and dissolved organic carbon by Fenton discoloration was investigated using the synthetic dye wastewaters containing various dyes (reactive blue 19, Eriochrome Black T or Fast Green FCF). The results indicated that discoloration of dyes was very rapid but mineralization of dyes was insignificant based on the removal of dissolved organic carbon. The rates of color, dye and dissolved organic carbon removal were in the order of reactive blue 19 > Fast Green FCF > Eriochrome Black T. The generation of SO(2-)4, and N(O-)3, increased with the progress of the Fenton reaction. The concentrations of SO(-2)4 and N(O-)3, generated are in the order of reactive blue 19 > Fast Green FCF> Eriochrome Black T. A mathematic model was proposed to formulate the formation of SO(2-)4 and N(O-)3 during dye degradation. Results indicated that one S-containing and two N-containing functional groups are involved in the oxidation reaction, and that S-containing groups are involved in the oxidation reaction earlier than N-containing functional groups.

Monitoring of microcystin-protein phosphatase adduct formation with immunochemical methods

Using anti-microcystin-LR monoclonal antibodies, an immunoblotting procedure was developed to monitor the formation of microcystin-protein phosphatase adducts in vitro and in vivo. The detection limits for the covalent binding of MCYST-LR with the recombinant protein phosphatase 1 (PP1) and rabbit liver cytosol proteins were found to be 0.1 ng and 0.3 ng per assay, respectively. MCYST-PP1 adducts were detected 30 s after the addition of MCYST-LR into the reaction mixture. Reduction of the methyldehydroalanine (Mdha) residue of MCYST-LR with ethanethiol totally abolished the covalent binding of the toxin to PP1, but retained its inhibitory toxicity on PP1. Immunoblotting analyses and enzyme-linked immunosorbant assay showed that between 5 min to 16 h after i.p. injection of single dose (35 microg/kg) of MCYST-LR into mice, approximately 0-27% of the injected toxin was found covalently bound while 0.2-9.2% existed as free form in liver cytosol.

Development of a polyclonal antibody-based sensitive enzyme-linked immunosorbent assay for fumonisin B(4)

Polyclonal antibodies (PAb) against fumonisin B(4) (FmB(4)), which have good cross-reactivity with four major fumonisins, were produced by immunizing a rabbit with FmB(4)-keyhole limpet hemocyanin conjugate. A sensitive competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for fumonisins was developed. Because of the limited supply of FmB(4), both FmB(1)-horseradish peroxidase conjugate (HRP) and FmB(3)-HRP were tested as the toxin-enzyme markers in the CD-ELISA. In the FmB(1)-HRP-based CD-ELISA, the concentrations of FmB(1), FmB(2), FmB(3), and FmB(4) causing 50% inhibition of binding of enzyme marker (IC(50)) were 9.0, 2.1, 9.0, and 6.5 ng/mL (or the relative cross-reactivities toward FmB(1), FmB(2), FmB(3), and FmB(4) were 58.5, 309.5, 58.5, and 100%), respectively. In the FmB(3)-HRP-based CD-ELISA, the IC(50) values for FmB(1), FmB(2), FmB(3), and FmB(4) were 7.1, 1.9, 7.6, and 5.3 ng/mL (or the relative cross-reactivities toward FmB(1), FmB(2), FmB(3), and FmB(4) were 74, 280, 70, and 100%), respectively. The FmB(3)-HRP-based CD-ELISA was then used in a series of analytical recovery experiments using Fusarium moniliforme corn culture material spiked with FmB(1) and with clean corn spiked with a FmB(3)/FmB(4)-containing extract. The overall recovery of FmB(1) from culture material in the range of 10-100 ppm was 65%. The detection limit for FmB(1) with clean corn as matrix was between 100 and 500 ppb. F. moniliforme cultures were analyzed with the developed CD-ELISA and a well-established FmB(1) antibody-based ELISA, which is not sensitive to FmB(4). Differences in the fumonisin levels found by the two assays were used as an indication of the presence of FmB(4) in the culture material and, therefore, as a method to identify FmB(4)-producing strains. Using ELISA in combination with HPLC individual B-series fumonisins were quantified. The ELISA developed in the present study would be a useful supplement to FmB(1) antibody-based ELISA for screening of Fusarium strains for the production of major fumonisins.

Production and characterization of a monoclonal anti-anti-idiotype antibody against fumonisin B(1)

A monoclonal anti-anti-idiotype antibody (mAb3) against fumonisin B(1) (FmB1) was produced from the hybridoma cell line 7C7F4, which was generated by the fusion of P3/NS-1/1-AG4-1 myeloma cells with spleen cells isolated from a Balb/c mouse that had been immunized with the Fab fragments of affinity-purified anti-idiotype antibodies. The mAb3 belongs to the immunoglobulin M, kappa light chain. A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) and an indirect competitive ELISA (idc-ELISA) were established for antibody characterization and toxin analysis. In an idc-ELISA using FmB1-ovalbumin (OVA) as the coating antigen, the concentrations causing 50% inhibition of binding (IC(50)) of mAb3 to the solid-phase FmB1-OVA by free FmB1, FmB2, and FmB3 were found to be 75, 95, and 450 ng/mL, respectively. In the dc-ELISA, the concentration causing IC(50) of FmB1-horseradish peroxidase to the solid-phase mAb3 by free FmB1 was found to be 233 ng/mL. Analysis of 12 samples naturally contaminated with fumonisins with mAb3-based idc-ELISA and polyclonal-based dc-ELISA showed a good correlation between these two methods with a correlation coefficient of 0.76 at p < 0.02. The linear regression slope was found to be y[polyclonal ELISA] = 0.87x[mAb3 ELISA] - 52 ppb.

Analysis of fumonisins and Alternaria alternata toxin by liquid chromatography-enzyme-linked immunosorbent assay

Use of a direct competitive enzyme-linked immunosorbent assay (ELISA) as a postcolumn monitoring system after liquid chromatography (LC) is described for analysis of different fumonisin analogs. Without cleanup and derivatization, sample extracts are directly injected into a C18 reversed-phase column and then subjected to LC. Fractions (0.5 mL each) are collected and then analyzed by ELISA. LC using a water-methanol gradient separated the 3 major fumonisins FmB1, FmB2, and FmB3, and as low as 0.1 ng FmB1 could be detected. Recovery of FmB1 added to ground corn (100-1000 ng/g) and then extracted with CH3CN-H2O (1 + 1, v/v) was 78.8%. Analysis of fumonisins in one starch and 14 naturally contaminated corn samples showed that FmB1 was the major fumonisin. Ten samples also were contaminated with FmB2, but only 2 samples were contaminated with FmB3. The method also was used to analyze extracts from cultures of 3 Alternaria alternata (AAL) strains. Both FmB1 and the AAL toxin TA were detected in the culture extracts, and their amounts varied considerably with the cultures tested.

[Study on drawing aseptic gas in diluting drugs]

In this study, the gas was drawn from sealed aseptic bottles, the blue flame of an alcohol lamp, and the air of the same treatment room. And the gas was put into aseptic solutions of 10% glucose separately and dripped. Then the samples were taken for bacteriaculture at appointed time-points. Meanwhile, the gases were drawn and put into aseptic solutions of 10% glucose separately. Then deactived penicillines were diluted with the solutions separately. Finally, the penicillines were mixed with 10% glucose and dripped. The samples were taken for bacteria-culture in the same way. The results showed that there was no colony existed in the gas from the sealed aseptic bottles and the flame of the alcohol lamp. However, colonies existed in the samples from the air of the treatment room. It is suggested that sealed aseptic gas should be drawn and kept for use in diluting drugs.