[Preoperative prediction of HER-2 expression status in breast cancer based on MRI radiomics model]

Objective: This study aims to explore the predictive value of T2-weighted imaging (T2WI), apparent diffusion coefficient (ADC), and early-delayed phases enhanced magnetic resonance imaging (DCE-MRI) radiomics prediction model in determining human epidermal growth factor receptor 2 status in breast cancer. Methods: A retrospective study was conducted, involving 187 patients with confirmed breast cancer by postsurgical pathology at Zhenjiang First People's Hospital during January 2021 and May 2023. Immunohistochemistry or fluorescence in situ hybridization was used to determine the HER-2 status of these patients, with 48 cases classified as HER-2 positive and 139 cases as HER-2 negative. The training set was used to construct the prediction models and the validation set was used to verify the prediction models. Layers of T2WI, ADC, and early-delayed phase DCE-MRI images were used to delineate the volumeof interest and 960 radiomic features were extracted from each case using Pyradiomic. After screening and dimensionality reduction by intraclass correlation coefficient, Pearson correlation analysis, least absolute shrinkage, and selection operator, the radiomics labels were established. Logistic regression analysis was used to construct the T2WI radiomics model, ADC radiomics model, DCE-2 radiomics model, DCE-6 radiomics model, and the joint sequence radiomics model to predict the HER-2 expression status of breast cancer, respectively. Based on the clinical, pathological, and MRI image characteristics of patients, univariate and multivariate logistic regression analysis wasused to construct a clinicopathological MRI feature model. The radscore of every patient and the clinicopathological MRI features which were statistically significant after screening were used to construct a nomogram model. The receiver operating characteristic (ROC) curve was used to evaluate the predictive performance of each model and the decision curve analysis wasused to evaluate the clinical usefulness. Results: The T2WI, ADC, DCE-2, DCE-6, and joint sequence radiomics models, the clinicopathological MRI feature model, and the nomogram model were successfully constructed to predict the expression status of HER-2 in breast cancer. ROC analysis showed that in the training set and validation set, the areas under the curve (AUC) of the T2WI radiomics model were 0.797 and 0.760, of the ADC radiomics model were 0.776 and 0.634, of the DCE-2 radiomics model were 0.804 and 0.759, of the DCE-6 radiomics model were 0.869 and 0.798, of the combined sequence radiomics model were 0.908 and 0.847, of the clinicopathological MRI feature model were 0.703 and 0.693, and of the nomogram model were 0.938 and 0.859, respectively. In the training set, the combined sequence radiomics model outperformed the clinicopathological features model (P＜0.001). In the training and validation sets, the nomogram outperformed the clinicopathological features model (P＜0.05). In addition, the diagnostic performance of the nomogram was better than that of the four single-modality radiomics models in the training cohort (P＜0.05) and was better than that of DCE-2 and ADC models in the validation cohort (P＜0.05). Decision curve analysis indicated that the value of individualized prediction models was higher than clinical and pathological prediction models in clinical practice. The calibration curve showed that the multimodal radiomics model had a high consistency with the actual results in predicting HER-2 expression. Conclusions: T2WI, ADC and early-delayed phase DCE-MRI imaging histology models for HER-2 expression status in breast cancer are expected to provide a non-invasive virtual pathological basis for decision-making on preoperative neoadjuvant regimens in breast cancer.

A recombinase polymerase amplification-SYBR Green I assay for the rapid and visual detection of Brucella

Brucellosis is a zoonosis caused by Brucella, which poses a great threat to human health and animal husbandry. Pathogen surveillance is an important measure to prevent brucellosis, but the traditional method is time-consuming and not suitable for field applications. In this study, a recombinase polymerase amplification-SYBR Green I (RPAS) assay was developed for the rapid and visualized detection of Brucella in the field by targeting BCSP31 gene, a conserved marker. The method was highly specific without any cross-reactivity with other common bacteria and its detection limit was 2.14 × 104 CFU/mL or g of Brucella at 40 °C for 20 min. It obviates the need for costly instrumentation and exhibits robustness towards background interference in serum, meat, and milk samples. In summary, the RPAS assay is a rapid, visually intuitive, and user-friendly detection that is highly suitable for use in resource-limited settings. Its simplicity and ease of use enable swift on-site detection of Brucella, thereby facilitating timely implementation of preventive measures.

Atypical Sweet syndrome: skin sinus tracts in an acutely febrile patient after lymphoma treatment: a case report

Sweet syndrome (SS) is an uncommon inflammatory disease that involves painful skin, edematous, red papules, plaques, or nodules often accompanied by fever and leukocytosis. SS has three subtypes, including classical, malignant-tumor associated, and drug-induced SS (DISS). Patients with DISS have clear histories of recent drug exposure. The incidence of SS is high in hematological malignancy but rare in lymphomas. Glucocorticoid treatment is the recommended treatment for all subtypes of SS. This case study describes a male patient who had a history of sALCL(Systemic anaplastic large cell lymphoma) and was treated with multiple cycles of monoclonal-antibody (mAb) therapy. They also received the G-CSF injection at the site where skin lesions later developed. They met the diagnosis criteria for DISS, which was considered to be caused by the G-CSF injection. In addition, BV(Brentuximab vedotin) administration might predispose them to DISS. This case illustrates the first reported SS during the lymphoma treatment, with rare clinical presentations of local crater-like suppurative skin lesions. This case expands the available literature on SS and hematologic neoplasms and reminds clinicians to promptly recognize and diagnose SS to minimize patient morbidity and long-term sequelae.

[Research progress in stent associated respiratory tract infection]

Airway stents are commonly used to treat patients with central airway obstruction, but several complications have been identified, including mucus plugging, granulation tissue, stent migration, and infection. Stent associated respiratory tract infection (SARTI) has often been neglected by the practicing clinicians. Therefore, we reviewed the available current literatures on the diagnosis and management of stent associated respiratory tract infection.

[Treatment outcome of 100 patients with hepatoblastoma based on a new risk stratification]

Objective: To provide the risk stratification method of hepatoblastoma (HB) suitable for implementation in China and explore the new treatment method for high-risk HB patients. Methods: A total of 100 cases of children and adolescents under 18 years old with newly diagnosed HB in Sun Yat-sen University Cancer Center and Sun Yat-sen University First Affiliated Hospital from September 2014 to September 2018 were included. According to the clinical stage, AFP level, pathological subtype and other factors, patients were stratified into four groups: extremely low-, low-, intermediate- and high-risk. The patients at very low risk were treated with surgery only and followed-up. The patients at very low risk were treated with C5V(Cisplatin+ 5-Fluroracil+ Vincristine) regimen for 4 courses. The patients at intermediate risk were treated with C5VD(Cisplatin+ 5-Fluroracil+ Vincristine+ Doxorubicin)regimen before and after surgery for 6-8 courses. The patients at high risk were treated with C5VD and IIV (ifoshamide+ irinotecan+ vincristine) alternately before and after surgery for 8 courses. Results: One hundred patients were stratified into extremely low-risk, low-risk, medium-risk and high-risk groups for 2, 10, 51 and 37 cases, respectively. Eighty three cases had evaluable lesions before chemotherapy. Among them, 65 patients achieved partial remission, stable disease and progressive disease were observed in 10, and 8 cases, respectively, with a response rate of 78.3%. During a median follow-up of 20 months, 30 patients experienced tumor relapse or progression, and 27 of them died. The 2-years progression-free survival (PFS) and overall survival (OS) rates were 69.2% and 72.0%, respectively. The 2-years PFS rates of patients with extremely low risk, low risk, medium risk and high risk were 100%, 88.9%, 75.3% and 43.2%, respectively. The 2-years OS rates were 100%, 100%, 81.0% and 44.8%, respectively. Conclusions: The novel HB risk classification is simple and feasible. With active comprehensive treatment, patients at extremely low-, low- and medium-risk have excellent outcomes. The survival rate of high-risk HB patients remains to be improved, and new treatment strategies need to be explored.

Identification of chicken-derived scFv against N-glycolylneuraminic acid retrieved from an immune library by phage display

N- glycolylneuraminic acid (Neu5Gc) is a type of sialic acid, it can be synthesized by a range of mammals except chickens and healthy human. After entering human body, Neu5Gc in foods such as red meat and milk can cause chronic inflammation, thus promoting the development of cancer and related diseases. In this study, we identified a gene sequence of Neu5Gc-specific single-chain variable fragment (ScFv) by phage display from a primary chicken antibodies library. Then the gene sequence was used to express a 29 kDa anti-Neu5Gc ScFv protein as detection probe in competitive inhibition ELISA (IC-ELISA). The linear regression equation of the IC-ELISA was y = 23.12x+33.19 (R = 0.980), and the half-maximal inhibitory concentration (IC50) and the limit of detection (LOD) was 5.333 and 0.66 μg/mL. The mean recovery of the spiked samples was 83.04%, and the intra-assay and inter-assay coefficients of variation (CVs) were both 5.59%. The results suggested that the specific anti-Neu5Gc ScFv is a promising probe for the development of IC-ELISA and test strip in order to detect the presence of Neu5Gc in red meat, milk, and tumor tissues.

[A single-center retrospective analysis of 85 children and adolescents with limited-stage Hodgkin lymphoma]

Objective: To summarize the efficiency and long-term outcomes of limited-stage Hodgkin lymphoma in children and adolescents with ABVD therapy and determined whether omitting radiotherapy for a low-risk patient enabled the achievement of complete response (CR) after chemotherapy. Methods: We retrospectively analyzed data from 13 y (2004-2016) from patients aged ≤18 y with limited-stage HL admitted to the Sun Yat-sen University Cancer Center. Patients received treatment with ABVD chemotherapy alone or ABVD chemotherapy followed by low-dose involved field radiotherapy. Results: Total 85 subjects were eligible for study inclusion; the median age was 12 (3-18) y; 66 (77.6%) were men, 80 (94.1%) had stage-II disease, 56 (65.9%) were at low-risk, and the median follow-up duration was 72 (8-196) months; 12 relapsed, 2 had secondary neoplasm, and 2 died. The 5-year event free survival (EFS) was (85.6±3.8) %, and the overall survival (OS) was 100%. The 5-year EFS and OS was (89.1±4.2) % and 100%, respectively, for the low-risk cohort and (79.3±7.5) % and 100%, respectively for the intermediate-risk cohort. Among the 39 low-risk patients who achieved CR after chemotherapy, 15 received treatment with chemotherapy followed by LD-IFRT. In the exploratory subset analysis, the low-risk cohort who achieved CR after chemotherapy, the 5-year EFS for comparing ABVD alone with chemotherapy followed by LD-IFRT was (87.0±7.0) % versus 100% (P=0.506) , and the OS was 100% for both the groups. Conclusions: Our retrospective analysis showed excellent survival of limited-stage HL patients with ABVD therapy. For patients who achieving CR after chemotherapy with low-risk HL, received chemotherapy followed by LD-IFRT does not improve 5-year OS and EFS. The use of risk- and response-based stratification may facilitate the development of effective and less toxic protocols.

Cholecystokinin type 2 receptor in colorectal cancer: diagnostic and therapeutic target

INTRODUCTION

Cholecystokinin type 2 receptor (CCK2R), which mediates the action of gastrin and cholecystokinin (CCK), has been demonstrated to promote the proliferation of colorectal cancer (CRC). A number of studies showed that CCK2R overexpressed in gastric cancer and pancreatic cancer but few in CRC. The correlation between CCK2R expression and clinicopathological characteristics is also not clear.

METHODS

This study investigated CCK2R expression in a wide range of cell lines and clinical CRC samples, and explored expression pattern and prognostic value of CCK2R in relation to clinicopathological parameters. The location and expression levels of CCK2R were measured by immunocytochemical (ICC), qRT-PCR and Western blot. The druggability and antineoplastic effects of CCK2R as a therapeutic target were investigated using an anti-CCK2R targeting recombinant toxin named rCCK8PE38 by CCK-8 assay.

RESULTS

Compared with paracarcinoma tissues, tumor samples showed overexpression of CCK2R (p = 0.028) including both CRC tissue and plasma samples, with plasma detection showing a significant indication for CCK2R evaluation. Aberrant expression correlated significantly with histological type (p = 0.032) and p53 status (p < 0.01), and patients with CCK2R overexpression had significantly lower disease-free survival. Application of rCCK8PE38 demonstrated the specificity and druggability of CCK2R as a therapeutic target, providing a strategy for clinical case screening of drugs targeting CCK2R.

CONCLUSION

This study highlighted the aberrant expression and clinical correlation of CCK2R and reveals its diagnostic, prognostic and treatment value in CRC. We hypothesize that CCK2R serve as a target for the diagnosis and treatment of this cancer.

Characterization of a Novel Interleukin-1 Receptor Antagonist from Sheep (Ovis aries)

Interleukin-1 receptor antagonist (IL-1Ra) is an antagonist of IL-1β binding IL-1β receptors but does not induce intracellular responses or signal transduction. In this study, the full-length complementary DNA (cDNA) of the IL-1Ra gene (OaIL-1Ra) was identified from sheep (Ovis aries) using rapid amplification of cDNA ends PCR and submitted to GenBank with the accession number KC425613. The OaIL-1Ra cDNA comprised an open reading frame of 525 bp encoding a protein of 19765.8 Da, a 5'-untranslated region (UTR) of 27 bp, and a 3'-UTR of 676 bp with a poly(A) tail. Recombinant OaIL-1Ra with bioactivity was expressed in a prokaryotic expression system, and a monoclonal antibody against native OaIL-1Ra was prepared. Through Western blot analyses, the OaIL-1Ra protein was widely expressed in lung, heart, spleen, liver, kidney, muscle, intestine, lymphonodi, rumen, and white blood cells, with the highest levels in liver and spleen. The expression of OaIL-1Ra in primary cultured white blood cells of sheep were highly induced in a time-dependent manner when challenged with different bacteria. These results implied that OaIL-1Ra is associated with immune responses during bacterial infections.

Host Prdx6 contributing to the intracellular survival of Brucella suis S2 strain

BACKGROUND

Brucellosis is a worldwide zoonotic infectious disease that is transmitted in various ways and causes great harm to humans and animals. The brucellosis pathogen is Brucella, which mainly resides in macrophage cells and survives and replicates in host cells. However, the mechanisms underlying Brucella survival in macrophage cells have not been thoroughly elucidated to date. Peroxiredoxin 6 (Prdx6) is a bifunctional protein that shows not only GSH peroxidase activity but also phospholipase A2 activity and plays important roles in combating oxidative damage and regulating apoptosis.

RESULTS

Recombinant mouse (Mus musculus) Prdx6 (MmPrdx6) was expressed and purified, and monoclonal antibodies against MmPrdx6 were prepared. Using the Brucella suis S2 strain to infect RAW264.7 murine macrophages, the level of intracellular Prdx6 expression first decreased and later increased following infection. Overexpressing Prdx6 in macrophages resulted in an increase in B. suis S2 strain levels in RAW264.7 cells, while knocking down Prdx6 reduced the S2 levels in cells.

CONCLUSIONS

Host Prdx6 can increase the intracellular survival of B. suis S2 strain and plays a role in Brucella infection.

[Impact of intensified maintenance therapy on the prognosis of children and adolescents with advanced lymphoblastic lymphoma]

目的

探讨增加维持治疗强度对Ⅲ期和Ⅳ期儿童青少年淋巴母细胞淋巴瘤（Lymphoblastic lymphoma, LBL）患者预后的影响。

方法

回顾性分析接受BFM-NHL-90/-95方案治疗且未做纵隔和中枢预防性放疗的Ⅲ期和Ⅳ期儿童青少年LBL患者的治疗结果。研究分组：1998年至2005年收治的患者于维持治疗阶段，在口服巯基嘌呤和甲氨蝶呤的基础上，定期采用“足叶乙甙+阿糖胞苷”和大剂量甲氨蝶呤交替进行化疗，为强化维持治疗组；其余为非强化维持治疗组。

结果

187例LBL患者纳入研究，其中强化维持治疗组52例，非强化维持治疗组135例，两组患者的性别、年龄、免疫分型、临床分期、危险度分层、受累部位的差异均无统计学意义（P值均>0.05）；中位随访48（0.5～221）个月，两组患者的5年无事件生存（EFS）率分别为（76.9±5.8）%和（77.9±4.3）%（χ²＝0.249，P＝0.617），5年总生存（OS）率分别为（78.8±5.7）%和（79.8±4.1）%（χ²＝0.353，P＝0.552），差异均无统计学意义；亚组分析结果显示，两组患者在不同临床分期（Ⅲ/Ⅳ期）、免疫分型（T/B-LBL）和危险分层（中/高危）中的EFS、OS率差异均无统计学意义（P值均>0.05）。维持治疗期间，强化维持治疗组和非强化维持治疗组患者Ⅲ、Ⅳ级骨髓抑制发生率分别为55.8%和18.5%（χ²＝25.363，P<0.05）。

结论

提高维持治疗强度并未提高Ⅲ期和Ⅳ期儿童青少年LBL患者的长期生存且可增加骨髓抑制等治疗相关不良反应。

[Efficacy and safety of decitabine in combination with G-CSF, low-dose cytarabine and aclarubicin in MDS-EB and AML-MRC]

Objective: To evaluate the clinical efficacy and safety of decitabine in combination with lower-dose CAG regimen (G-CSF, cytarabine and aclarubicin; D-CAG regimen) in the treatment of myelodysplastic syndromes with excess blasts (MDS-EB) and acute myeloid leukemia with myelodysplasia-related changes (AML-MRC), compared to standard CAG regimen. Methods: A total of 42 patients with newly diagnosed MDS-EB and AML-MRC from May 2011 to March 2017 were included in the retrospective study. 21 cases were initially treated with G-CSF for priming, in combination with cytarabine of 10 mg/m(2) q12h for 14 days and aclarubicin of 20 mg/d for 4 days (CAG regimen) and the other 21 cases were initially treated with decitabine of 20 mg/m(2) for 5 days and lower-dose CAG regimen (cytarabine of 10 mg/m(2) q12h for 7 days, aclarubicin of 10 mg/d for 4 days, and G-CSF for priming (D-CAG regimen). After two cycles of induction chemotherapy, the patients who obtained complete remission(CR) received consolidation chemotherapy or hematopoietic stem cell transplantation (HSCT). Results: Among a total of 42 patients, the median age was 52.5 years (18-65 years) and 64.3% of them were male. Baseline characteristics of patients between D-CAG group and CAG group showed no significant differences. The CR for patients in D-CAG group was 81.0% (17/21), compared to 52.4% (11/21) in CAG group after 2 cycles of therapy (χ(2)=3.857, P=0.050). The overall response rate (ORR) for patients in D-CAG group and CAG group was 85.7% (18/21) and 76.2% (15/21) respectively, without significant difference (χ(2)=1.273, P=0.259). By December 2017, the median follow-up of D-CAG group and CAG group was 13(6-32) months and 15(2-36) months respectively. Finally, 10 patients in D-CAG group and 7 patients in CAG group received HSCT respectively. Except patients receiving HSCT, the median leukemia-free survival (LFS) time for patients in D-CAG group and CAG group was 18.0 (95%CI 6.6-29.4) months and 11.0 (95%CI 0-23.9) months respectively. Probabilities of 12 months LFS for D-CAG group and CAG group were (63.6±14.5)% and (50.0±13.4)% respectively, without difference (χ(2)=0.049, P=0.824). Except patients receiving HSCT, there were 2 deaths in D-CAG group and 7 deaths in CAG group respectively. The cumulative probabilities of 12 months OS for non-HSCT patients in D-CAG group and CAG group were (90.9±8.7)% and (61.5±13.5)% respectively, without significant difference (χ(2)=1.840, P=0.175). The incidences of side effects between D-CAG group and CAG group did not show significant differences (P=0.479), and the main side effects included cytopenias, pneumonia, infections of skin and soft tissues, neutropenic patients with fever, liver dysfunction. Conclusion: The decitabine in combination with lower-dose CAG regimen improved CR for patients with MDS-EB and AML-MRC, and was a promising choice.

[Influence of gender, age and season on thyroid hormone reference interval]

Objective: Using clinical "big data" , to investigate the factors that affect the levels of thyroid hormones, and to explore the partitioning criteria for reference intervals (RI) of these hormones. Methods: An observation study was conducted. Information of 107 107 individuals undergoing routine physical examination in Peking Union Medical College Hospital from September 1(st,) 2013 to August 31(st,) 2016 was collected, thyroid hormone of these subjects were detected. To explore the test results distribution and differences of TSH, FT4 and FT3 by gender and age; according to the seasonal division standard of China Meteorological Administration, the study period was divided into four seasons, and the seasonal fluctuation on TSH was analyzed.To define the appropriate partition by gender, age and season according to significant difference analysis. Results: In male and female, the distributions of TSH were 1.779(0.578-4.758), 2.023(0.420-5.343)mU/L, respectively, and the level of TSH in female was higher than in male (Z=-37.600, P<0.001). The distributions of FT4 were 0.127(0.098-0.162), 0.117(0.091-0.151) μg/L, the distributions of FT3 were 3.33(2.47-3.74), 3.01(2.35-3.57)ng/L. And the level of FT4, FT3 in female were significantly lower than in male (Z=-94.000, -154.600, all P<0.001). Furthermore, males were divided into two groups by 65 years old and female were divided by 50 years old, respectively, and the distributions of TSH in male and female of older group were 1.818(0.528-5.240), 2.111(0.348-5.735)mU/L, in younger group were 1.778(0.582-4.696), 1.991(0.427-5.316)mU/L. The level of TSH in older group was significantly higher than in younger group (Z=-2.269, -10.400, all P<0.05), and the distribution of TSH in older group was much wider than in younger. The distribution of whole in spring, summer and autumn was 1.869( 0.510-5.042)mU/L, in winter was 1.978(0.527-5.250) mU/L, and the difference between them had statistical significance (Z=-15.000, P<0.001). Conclusions: Gender and age significantly affect the serum levels of TSH, FT4, and FT3, the distribution of TSH in female and elder group are wider than in male, and that of FT4, FT3 are lower.Seasons significantly affect the serum TSH level, the peak value is observed in winter. There are obviously differences between "rough" RIs and manufacture recommended RIs. Each laboratory should establish reference intervals for thyroid hormones on the premise of appropriate grouping.

Cloning and Differential Expression Analyses of Cdc42 from Sheep

INTRODUCTION

Serological diagnosis of brucellosis is still a great challenge due to the infeasibility of discriminating infected animals from vaccinated ones, so it is necessary to search for diagnostic biomarkers for differential diagnosis of brucellosis.

MATERIAL AND METHODS

Cell division cycle 42 (Cdc42) from sheep (Ovis aries) (OaCdc42) was cloned by rapid amplification of cDNA ends (RACE), and then tissue distribution and differential expression levels of OaCdc42 mRNA between infected and vaccinated sheep were analysed by RT-qPCR.

RESULTS

The full-length cDNA of OaCdc42 was 1,609 bp containing an open reading frame (ORF) of 576 bp. OaCdc42 mRNAs were detected in the heart, liver, spleen, lung, kidneys, rumen, small intestine, skeletal muscles, and buffy coat, and the highest expression was detected in the small intestine. Compared to the control, the levels of OaCdc42 mRNA from sheep infected with Brucella melitensis or sheep vaccinated with Brucella suis S2 was significantly different (P < 0.01) after 40 and 30 days post-inoculation, respectively. However, the expression of OaCdc42 mRNA was significantly different between vaccinated and infected sheep (P < 0.05 or P < 0.01) on days: 14, 30, and 60 post-inoculation, whereas no significant difference (P > 0.05) was noted 40 days post-inoculation. Moreover, the expression of OaCdc42 from both infected and vaccinated sheep showed irregularity.

CONCLUSION

OaCdc42 is not a good potential diagnostic biomarker for differential diagnosis of brucellosis in sheep.

Clinical targeting recombinant immunotoxins for cancer therapy

Recombinant immunotoxins (RITs) are proteins that contain a toxin fused to an antibody or small molecules and are constructed by the genetic engineering technique. RITs can bind to and be internalized by cells and kill cancerous or non-cancerous cells by inhibiting protein synthesis. A wide variety of RITs have been tested against different cancers in cell culture, xenograft models, and human patients during the past several decades. RITs have shown activity in therapy of several kinds of cancers, but different levels of side effects, mainly related to vascular leak syndrome, were also observed in the treated patients. High immunogenicity of RITs limited their long-term or repeat applications in clinical cases. Recent advances in the design of immunotoxins, such as humanization of antibody fragment, PEGylation, and modification of human B- and T-cell epitopes, are overcoming the above mentioned problems, which predict the use of these immunotoxins as a potential therapeutic method to treat cancer patients.

Characterization of a highly virulent and antimicrobial-resistant Acinetobacter baumannii strain isolated from diseased chicks in China

Poultry husbandry is a very important aspect of the agricultural economy in China. However, chicks are often susceptible to infectious disease microorganisms, such as bacteria, viruses and parasites, causing large economic losses in recent years. In the present study, we isolated an Acinetobacter baumannii strain, CCGGD201101, from diseased chicks in the Jilin Province of China. Regression analyses of virulence and LD50 tests conducted using healthy chicks confirmed that A. baumannii CCGGD201101, with an LD50 of 1.81 (±0.11) × 10(4) CFU, was more virulent than A. baumannii ATCC17978, with an LD50 of 1.73 (±0.13) × 10(7) CFU. Moreover, TEM examination showed that the pili of A. baumannii CCGGD201101 were different from those of ATCC17978. Antibiotic sensitivity analyses showed that A. baumannii CCGGD201101 was sensitive to rifampicin but resistant to most other antibiotics. These results imply that A. baumannii strain CCGGD201101 had both virulence enhancement and antibiotic resistance characteristics, which are beneficial for A. baumannii survival under adverse conditions and enhance fitness and invasiveness in the host. A. baumannii CCGGD20101, with its high virulence and antimicrobial resistance, may be one of the pathogens causing death of diseased chicks.

Preparation of a Specific ssDNA Aptamer for Brevetoxin-2 Using SELEX

The existing assays for detecting brevetoxin (BTX) depend on expensive equipment with a professional operator or on an antibody with limited stability, which requires complex processes, a high cost, and a considerable amount of time. The development of an alternative detection probe is another promising research direction. This paper reports the use of aptamers binding to BTX-2 in an analytical assay using the systematic evolution of ligands by exponential enrichment (SELEX). After 12 rounds of selection, the secondary structures of 25 sequences were predicted. Compared to other aptamers, Bap5 has relatively high affinity with the lowest dissociation constant of 4.83 μM, and IC₅₀ is 73.81 ng mL^-1. A good linear regression formula of y = 30.688x - 7.329 with a coefficient correlation of R² = 0.9798 was obtained using a biotin-avidin ELISA. Moreover, there is no cross-reaction with the detected marine toxins, except for BTX-2. Thus, Bap5 has potential to detect BTX-2 in shellfish in the future as a substitute for the recognition probe.

Isolation and characterisation of peroxiredoxin 6 promoter from sheep (Ovis aries)

Introduction: Peroxiredoxin 6 (Prdx6) is a bifunctional protein and a unique 1-Cys Prdx of the peroxiredoxin family. The expression and regulation of Prdx6 are implicated in numerous physiological and pathological processes.

Material and Methods: Eight stepwise truncated DNA fragments obtained from the 5′-flank region of the Prdx6 gene were prepared and subcloned into the pSEAP2-Enhancer vectors. To investigate the transcriptional activity of the truncated DNA fragments, the recombinant plasmids were transfected into the COS-1 cells and the transcriptional activity was measured via assaying the expression of the reporter gene of the secreted alkaline phosphatase.

Results: A 3.4 kb 5′-upstream flank region of the Prdx6 gene was cloned and sequenced. The region from −108 nt to −36 nt of the 5′-flanking region of the Prdx6 gene contained basal transcriptional activity.

Conclusion: This result provides the basis for further studies on the gene regulation of the Prdx6-mediated biological processes and on screening for the transacting factors that interact with cis-acting elements of the Prdx6 gene promoter.

Generation of Internal-Image Functional Aptamers of Okadaic Acid via Magnetic-Bead SELEX

Okadaic acid (OA) is produced by Dinophysis and Prorocentrum dinoflagellates and primarily accumulates in bivalves, and this toxin has harmful effects on consumers and operators. In this work, we first report the use of aptamers as novel non-toxic probes capable of binding to a monoclonal antibody against OA (OA-mAb). Aptamers that mimic the OA toxin with high affinity and selectivity were generated by the magnetic bead-assisted systematic evolution of ligands by exponential enrichment (SELEX) strategy. After 12 selection rounds, cloning, sequencing and enzyme-linked immunosorbent assay (ELISA) analysis, four candidate aptamers (O24, O31, O39, O40) were selected that showed high affinity and specificity for OA-mAb. The affinity constants of O24, O31, O39 and O40 were 8.3 × 10⁸ M⁻¹, 1.47 × 10⁹ M⁻¹, 1.23 × 10⁹ M⁻¹ and 1.05 × 10⁹ M⁻¹, respectively. Indirect competitive ELISA was employed to determine the internal-image function of the aptamers. The results reveal that O31 has a similar competitive function as free OA toxin, whereas the other three aptamers did not bear the necessary internal-image function. Based on the derivation of the curvilinear equation for OA/O31, the equation that defined the relationship between the OA toxin content and O31 was Y = 2.185X − 1.78. The IC₅₀ of O31 was 3.39 ng·mL⁻¹, which was close to the value predicted by the OA ELISA (IC₅₀ = 4.4 ng·mL⁻¹); the IC₁₀ was 0.33 ng·mL⁻¹. The above data provides strong evidence that internal-image functional aptamers could be applicable as novel probes in a non-toxic assay.

An improved RT-IPCR for detection of pyrene and related polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous homogeneous chemicals which are well known by carcinogens, mutagens and endocrine disorder. Here, an improved real-time immuno-PCR (RT-IPCR) was developed for detection of pyrene and its homologs in water samples. The PAHs in sample compete with pyrene-modified DNA to bind with monoclonal antibody (McAb) coated on PCR plate. The reporter DNA was exponentially amplified by real-time PCR instrument using Fast Start universal SYBR Green Master (ROX) kit. Only two reaction steps were needed to accomplish the detection. The assay had a good linear range from 5 pmol L(-1) to 5 nmol L(-1) with a detection limit of 3.5 pmol L(-1). For application assay, the average recoveries from tap water, lake water and mineral water were 98.4%, 98.2% and 99.7%, respectively which showed a good correlation (R(2)=0.9906) with those from GC-MS. The results indicated that the improved RT-IPCR seems to be a potential method for simple and ultrasensitive detection of pyrene and some homologues in environment water samples.

Expression, purification and characterization of recombinant toxins consisting of truncated gastrin 17 and pseudomonas exotoxin

Gastric cancer is a major cause of mortality and morbidity around world. However the effectiveness of the current approaches to the diagnosis and treatment of gastric cancer is limited. Recombinant targeted toxins may represent a novel direction of cancer therapy. In this study, we aimed to explore whether recombinant toxins fused with the truncated forms of G17 could target to kill cancer cells by recognizing CCK2R. Four recombinant Pseudomonas toxins PE38 fused with the forward or reverse truncated forms of G17 (G14 and G13) were successfully constructed, expressed, and purified. Their characteristics were further analyzed by SDS-PAGE, western blot and indirect immunofluorescence assay. The cytotoxicity assay demonstrated that only reversely fused recombinant toxins rG14PE38 and rG13PE38 exhibited certain toxicity on several cancer cell lines, and a competition assay indicated that the binding of the reverse gastrin-endotoxin to CCK2R (+) cells may be mediated by interaction between gastrin/gastrin-like and CCK2R.

Reducing dioxin formation by adding hydrogen in simulated fly ash

In this study, simulated fly ash containing CuO/CuCl2 was heated at 350 °C in a flow of N2 and also in a nitrogen flow containing 10 vol% H2, to evaluate the influence of hydrogen adding on dioxin formation. The total polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) output derived from the CuO sample under N2 and 10 % H2 was 7.382 and 0.708 ng/g, respectively. As for CuCl2, it was 589 and 46.1 ng/g, respectively. The results show that the hydrogen adding has a good inhibition effect on PCDD/F formation; the inhibition rate was higher than 90 % for PCDD/Fs. HCl and NH3 were detected by Gasmet in the flue gas; the probable inhibition mechanism of hydrogen reaction was proposed, based on our measurements and others' researches.

Contamination of commercially available seafood by key diarrhetic shellfish poisons along the coast of China

With the increasing number of outbreaks of food-borne diseases caused by okadaic acid (OA) and its analogue dinophysistoxin-1 (DTX-1), two key diarrhetic shellfish poison (DSP) toxins, OA and DTX-1, have become a serious threat to public health and have attracted significant public attention in China. The aim of our study was to monitor OA and DTX-1 contamination in commercially available seafood and to provide references for tracking these toxins and preventing disease outbreaks. From 2010 to 2012, 40 species were collected from six coastal cities of four inland seas in China. An enzyme-linked immunosorbent assay (ELISA) and a lateral flow immunochromatographic (LFIC) test strip were used to analyse the samples, and the results were further confirmed using a commercially available ELISA kit. The monitoring results indicated that 23 of 40 species were positive for contamination. In addition, 14 of the positive species were determined to be inedible because the content of OA and DTX-1 was above the regulatory limit. Simultaneously, we verified that the digestive glands of shellfish tended to accumulate toxin, in contrast to the flesh. The highest concentrations of OA and DTX-1 were recorded in Scapharca broughtonii, which was collected from Qing Dao, in relation to the other analysed species. Moreover, the Arca family as well as Mytilus galloprovincialis were severely contaminated by OA and its analogue. The above results indicate that some of the commercially available seafood from the coastal cities in China may be inedible due to serious marine toxin contamination. The results of this study might play an important role in protecting consumer health and safety screening of marine products.

Molecular cloning, expression and characterization of programmed cell death 10 from sheep (Ovis aries)

Programmed cell death 10 (PDCD10) is a highly conserved adaptor protein. Its mutations result in cerebral cavernous malformations (CCMs). In this study, PDCD10 cDNA from the buffy coat of Small Tail Han sheep (Ovis aries) was cloned from a suppression subtractive hybridization cDNA library, named OaPDCD10. The full-length cDNA of OaPDCD10 was 1343bp with a 639bp open reading frame (ORF) encoding 212 amino acid residues. Tissue distribution of OaPDCD10 mRNA determined that it was ubiquitously expressed in all tested tissue samples, and the highest expression was observed in the heart. The differential expression of OaPDCD10 between infected sheep (challenged with Brucella melitensis) and vaccinated sheep (vaccinated with Brucella suis S2) was also investigated. The results revealed that, compared to the control group, the expression of OaPDCD10 from infected and vaccinated sheep was both significantly up-regulated (p<0.05). Moreover, the expression levels of OaPDCD10 from the vaccinated sheep were significantly higher than the infected sheep (p<0.05) after 30days post-inoculation. The recombinant OaPDCD10 (rOaPDCD10) protein was expressed in Escherichia coli BL21 (DE3), and then purified by affinity chromatography. The rOaPDCD10 protein was demonstrated to induce apoptosis and promote cell proliferation. Our studies are intended to discover potential diagnostic biomarkers of brucellosis to discern infected sheep from vaccinated sheep, and OaPDCD10 could be considered as a potential diagnostic biomarker of brucellosis.

Magnetic bead and gold nanoparticle probes based immunoassay for β-casein detection in bovine milk samples

In this work, a double-probe based immunoassay was developed for rapid and sensitive determination of β-casein in bovine milk samples. In the method, magnetic beads (MBs), employed as supports for the immobilization of anti-β-casein polyclonal antibody (PAb), were used as the capture probe. Colloidal gold nanoparticles (AuNPs), employed as a bridge for loading anti-β-casein monoclonal antibody (McAb) and horseradish peroxidase (HRP), were used as the amplification probe. The presence of β-casein causes the sandwich structures of MBs-PAb-β-casein-McAb-AuNPs through the interaction between β-casein and the anti-β-casein antibodies. The HRP, used as an enzymatic-amplified tracer, can catalytically oxidize the substrate 3,3',5,5'-tetramethylbenzidine (TMB), generating optical signals that are proportional to the quantity of β-casein. The linear range of the immunoassay was from 6.5 to 1520ngmL(-1). The limit of detection (LOD) was 4.8ngmL(-1) which was 700 times lower than that of MBs-antibody-HRP based immunoassay and 6-7 times lower than that from the microplate-antibody-HRP based assay. The recoveries of β-casein from bovine milk samples were from 95.0% to 104.3% that had a good correlation coefficient (R(2)=0.9956) with those obtained by an official standard Kjeldahl method. For higher sensitivity, simple sample pretreatment and shorter time requirement of the antigen-antibody reaction, the developed immunoassay demonstrated the viability for detection of β-casein in bovine milk samples.

Enzyme-antibody dual labeled gold nanoparticles probe for ultrasensitive detection of κ-casein in bovine milk samples

A dual labeled probe was synthesized by coating gold nanoparticles (AuNPs) with anti-κ-CN monoclonal antibody (McAb) and horseradish peroxidase (HRP) enzyme on their surface. The McAb was used as detector and HRP was used as label for signal amplification catalytically oxidize the substrate. AuNPs were used as bridges between the McAb and HRP. Based on the probe, an immunoassay was developed for ultrasensitive detection of κ-CN in bovine milk samples. The assay has a linear response range within 4.2-560 ng mL(-1). The limit of detection (LOD) was 4.2 ng mL(-1) which was 10 times lower than that of traditional McAb-HRP based ELISA. The recoveries of κ-CN from three brand bovine milk samples were from 95.8% to 111.0% that had a good correlation (R(2)=0.998) with those obtained by official standard Kjeldahl method. For higher sensitivity and as simple as the traditional ELISA, the developed immunoassay could provide an alternative approach for ultrasensitive detection of κ-CN in bovine milk sample.

Simple, specific, sensitive and rapid loop-mediated method for detecting Yersinia enterocolitica

Yersinia enterocolitica (YE) is a main pathogenic bacterium causing diarrhea and yersiniosis occurs in both developed and developing countries with high incidence. YE in contaminated food is able to survive for a long duration even under cold storage, thereby enhancing the risk of food infection. In this study, a new loop-mediated isothermal amplification (LAMP) method showing the characteristics of simplicity, rapidity, high specificity and sensitivity was established by targeting outL of pathogenic YE. Two inner-primers and outer-primers were designed and LAMP reaction was optimized for Mg2+, betaine, dNTPs and inner primers concentrations, reaction temperature and time. Sensitivity and specificity of the LAMP assay was evaluated using YE genomic DNA and those of 44 different bacteria strains, respectively. Validation of LAMP detection method was by employing meat samples spiked with varying CFU of YE. The optimized LAMP assay was specific, capable of detecting 97 fg of genomic DNA (equivalent to 37 genome copies) of YE (100-fold more sensitive than PCR) and 80 CFU/ml of YE-spiked meat samples based on ethidium bromide stained amplicon bands on agarose gel-electrophoresis and on GelRed fluorescence of the LAMP reaction solution, respectively. This rapid, sensitive and specific LAMP technique should enable application in field inspection of Y. enterocolitica in food.

A rapid immunomagnetic beads-based immunoassay for the detection of β-casein in bovine milk

An immunomagnetic beads-based enzyme-linked immunosorbent assay (IMBs-ELISA) was developed for the detection of β-casein in bovine milk. Immunomagnetic beads (IMBs) were employed as the solid phase. The anti-β-casein monoclonal antibody (McAb) bound to IMBs was used as capture probe and an anti-β-casein polyclonal antibody (PcAb), labelled with horseradish peroxidase (HRP), was employed as detector probe. Three reaction and two washing steps were needed. Each reaction needed 10 min or less, which significantly shortened detection compared with classic sandwich ELISA. β-Casein in bovine milk was detected across a linear range (2-128 μg mL(-1)). Application results were in accordance with the Kjejdahl method, which suggests the IMBs-ELISA is rapid and reliable for the detection of β-casein in bovine milk.

Production of a monoclonal antibody and development of an immunoassay for detection of Cr(III) in water samples

In this study we report the production of a monoclonal antibody (Mab) specific for Cr(III)-chelate and the development of a competitive immunoassay for detection of Cr(III) in water samples. In the assay, the complete antigen (Cr(III)-ITCBE-BSA) was used as coating antigen, and Cr(III)-ITCBE as competitor competes with coating antigen to bind with Mab. Using this approach, the spiked water samples with Cr(III) were detected. The linear range of the detection was 0.7-12.4 ng mL(-1). The limit of the detection (LOD) was 0.51 ng mL(-1). The spiked results were also confirmed by ICP-MS, which showed a good correlation (R(2)=0.997) between the two methods. The results indicated that the developed assay was reliable and suitable for the detection of Cr(III) in water samples.

Direct competitive immunosorbent assay for detection of MEHP in human urine

Di-(2-ethylhexyl) phthalate (DEHP) is the most commonly used plasticizer for flexible polyvinyl chloride (PVC), which is also known as one of the environmental endocrine disruptors with the reproductive, developmental and embryonic toxicity after entering human body. Mono-2-ethylhexyl phthalate (MEHP) is one of the most complicate metabolites from DEHP in vivo and responsible for many toxic effects of DEHP. In order to evaluate human exposure to DEHP, a direct competitive enzyme-linked immunosorbent (dcELISA) based on monoclonal antibody (mAb) was developed to detect MEHP. A hybridoma cell line 4B9 secreting mAb against MEHP was prepared, and the horseradish peroxidase (HRP) labeled antigen as a probe in the dcELISA was made. After optimization of ELISA reaction conditions, the standard curve with a linear range from 0.56 to 1000 ng mL(-1) and a detection limit of 0.39 ng mL(-1) was established. The cross-reactivities of anti-MEHP mAb to other ten phthalate esters were less than 5% except for mono-methylphthalate (MME). The average recoveries of MEHP from distilled water and negative human urine were both between 87.4% and 94.72% with coefficient of variation (CV) less than 5%. Here, the ELISA method on detecting MEHP was successfully established and applied to real urine sample analyses and the results were confirmed by HPLC. Furthermore, it was indicated that the immunoassay was reliable and suitable for monitoring MEHP.

A novel analytical probe binding to a potential carcinogenic factor of N-glycolylneuraminic acid by SELEX

N-glycolylneuraminic acid (Neu5Gc) is an abundant sialic acid in many mammals and is present in the glycoconjugates of most deuterostome animals. Neu5Gc also occurs in fresh samples of human tumors and fetuses. However, very little is known about the expression level and biologic functions of Neu5Gc due to the limitations of available analytical probes for detection methods. In this study, we first report the development of aptamers specific to Neu5Gc screened by Systematic Evolution of Ligands by Exponential Enrichment (SELEX). After 15 selection rounds, cloning, sequencing and enzyme-linked immuno sorbent assay (ELISA) analysis, 6 different selected aptamers showed specificity for Neu5Gc. Among these 6 aptamers, N8 showed the best half maximal inhibitory concentration (IC50) value (127 ng mL(-1)) and had a relatively high affinity constant (Ka=6.68 × 10(9)M(-1)). The aptamers selected in this study will provide a novel analytical probe for the development of a biosensor to detect Neu5Gc in tissues and sera from patients with tumors as well as to detect Neu5Gc in animal-derived foods. In addition, the successful aptamer candidate can solve the problem that antibody is difficult to prepare in immunological assays. Thus, the discovery of novel aptamers specific for Neu5Gc is important for developing new methods of detecting Neu5Gc for the diagnosis and prevention of cancer as well as food poisoning.

Dioxins and furans releases in Iranian mineral industries

In this project, emissions of Poly-Chlorinated Dibenzo-p-Dioxins and Dibenzo-Furans (PCDD/Fs) were investigated and estimated for selected Iranian mining and ore processing industries, such as integrated iron & steel plant, primary production of aluminium and copper metal, and the production of cement. As a first step of this study the annual emission of PCDD/Fs was estimated at 120gTEQannum(-1) on the base of the UNEP standardised Toolkit for identification and quantification of dioxin and furan releases. Steel and cement were identified as major emission sources and earmarked for further scrutiny. For that reason, filter dust arising in these plants was sampled and analysed, as well as all raw materials employed. After extraction and clean-up according to standard methods, the resulting liquid samples were analysed and quantified by HRGC-HRMS. Complementary analyses using methods such as XRF, TGA/DTA were performed and the emission results statistically evaluated, in order to put PCDD/F emissions in perspective. It is concluded that the dioxins load of cement dust is unusually low, following the low carbon in raw materials, the use of natural gas as a fuel and the absence of waste incineration. Also the production of iron by direct reduction of ore is a low dioxins process; dioxin loads in dust are as usual - correlated with the presence of catalytic metals. Loss on ignition and chlorine are anti-correlated with the main earth elements and with sulphur oxides.

In vitro and in vivo antitumor effects of the recombinant immunotoxin IL6(T23)-PE38KDEL in multiple myeloma

IL6(T23)-PE38KDEL is a chimeric molecule composed of interleukin 6 (IL6), missing the N-terminal 23 amino acids, and fused to a truncated mutant form of Pseudomonas exotoxin (PE38KDEL). The aim of this study was to evaluate this recombinant immunotoxin in terms of its specific cytotoxicity to IL6R-overexpressing multiple myeloma (MM) cells in vitro, as well as its antitumor effects and side effects in vivo. IL6(T23)-PE38KDEL was expressed in Escherichia coli, refolded and purified from inclusion bodies. The purified IL6(T23)-PE38KDEL was found to be selectively cytotoxic to IL6 receptor-positive tumor cells in vitro. IC(50) values of IL6(T23)-PE38KDEL were evaluated by MTS assay. Toxicity and maximum-tolerated dose of IL6(T23)-PE38KDEL were determined in mice. The antitumor activity of IL6(T23)-PE38KDEL was evaluated in mice with MM through intravenous injection and interventional therapy. Intravenous administration of IL6(T23)-PE38KDEL caused a significantly increased survival time in treated mice, and exhibited dose- and time-dependent antitumor effects against MM mice. Moreover, complete tumor regression was observed in 30 and 80% of mice treated intravenously and intraperitoneally, respectively, with 0.4 mg/kg/day for 10 days. These results demonstrated that the recombinant immunotoxin IL6(T23)-PE38KDEL kills IL6R-overexpressing cancer cells, and causes significant tumor regression.

Production of monoclonal antibody and application in indirect competitive ELISA for detecting okadaic acid and dinophytoxin-1 in seafood

BACKGROUND, AIM, AND SCOPE

Okadaic acid (OA) and analogues of dinophysistoxin (DTX) are key diarrheic shellfish poisoning (DSP) toxins, which possibly arouse DSP symptoms by consuming the contaminated shellfish. Because of the stable toxicity in high temperature and the long-term carcinogenicity, the outbreaks of DSP related to consumption of bivalve mollusks contaminated by DSP toxins pose a hazard to public health. Therefore, it is worth developing a fast and reliable analytical method for the detection of OA and analogues in shellfish. In this paper, an indirect competitive enzyme-linked immunosorbent assay (ELISA) (icELISA) for detecting OA and DTX-1 in seafood was developed based on monoclonal antibody (McAb).

METHODS

The OA was conjugated to human immunoglobulin G (IgG) and bovine serum albumin (BSA) by the active ester method as the immune antigen and the detective antigen. The spleen cells from BALB/c mice immunized with OA-IgG were fused with SP2/0 myeloma cells. A hybridoma cell line, which secreted McAb against OA, was selected by "limiting dilution" cloning. An icELISA was developed based on immobilized conjugate (OA-BSA) competing the McAb with the free OA in seafood sample.

RESULTS

A hybridoma cell line, which secreted IgG1 subclass monoclonal antibody (McAb) against OA, was selected. The IC(50) of the McAb for OA and dinophytoxin-1 (DTX-1) were 4.40 and 3.89 ng/mL, respectively. Based on the McAb, an indirect competitive ELISA for detection of OA and DTX-1 in seafood was developed. The regression equation was y = 54.713x - 25.879 with a coefficient correlation of R (2) = 0.9729. The linear range and the limit of detection were 0.4-12.5 and 0.45 ng/mL, respectively. The average recovery of OA and DTX-1 spiked shellfish was 82.29% with the coefficient of variation of 7.67%.

CONCLUSION

The developed icELISA is a fast, sensitive, and convenient assay for detecting of total amount of OA and DTX-1 in seafood.

Cloning, expression, and genus-specificity analysis of 28-kDa OmpK from Vibrio alginolyticus

Some Vibrio species are universal marine pathogens and Vibrio infections are often encountered due to consumption of raw or uncooked seafood. The outer membrane proteins, playing a key role in interaction between bacteria and hosts, are potential candidates for development of vaccine and markers of the genus Vibrio. In this study, the ompK (outer membrane protein K) genes of Vibrio alginolyticus, V. vulnificus, V. parahaemolyticus, V. fluvialis, and V. mimicu were cloned with 798 to 822 nucleotides encoding 266 to 274 amino acids. The ompK gene from V. alginolyticus was expressed in Escherichia coli using pET-22b expression vector. The recombinant fusion OmpK protein with 6xHis tag was purified with nickel chelate affinity chromatography. The polyclonal antibody (titer, 1:102400) against V. alginolyticus OmpK was developed in guinea pigs and it positively reacted with each of 5 Vibrio species but negative to other 18 Gram-negative bacterial strains. The result suggests that Vibrio OmpK protein could be a genus-specific antigen, which can be used for developing vaccines and rapid detection of multiple Vibrio species.

Colloidal gold probe-based immunochromatographic assay for the rapid detection of brevetoxins in fishery product samples

One-step immunochromatographic assay using colloidal gold-labeled monoclonal antibody (Mab) probe for the rapid detection of brevetoxins (PbTxs) in fishery product samples was developed. The described assay was based on a competitive format using two antibodies. The primary antibody was conjugated with colloidal gold (detector reagent), the secondary antibody (capture reagent) was immobilized within a defined detection zone (control line) on a diagnostic cellulose nitrate membrane. The toxin in sample compete with immobilized toxin to bind with gold conjugated Mab. The mobile complex (colloidal gold-Mab-toxin) can be captured by the secondary antibody but cannot be captured by BSA-PbTx (test line). The color density of the test line correlated with the concentration of PbTx in sample in the range 10-4000 ng mL(-1). Spiked samples were detected by the assay and the visual detection limit was found to be 20 ng mL(-1). This qualitative test based on the visual evaluation of results did not require any equipment. The assay time for PbTx detection was less than 10 min, suitable for rapid testing on-site.