A label-free reusable aptasensor for Alzheimer's disease.

To early effectively detect amyloid-beta (Aß) oligomers, a label-free reusable aptasensor was designed. This aptasensor based on a luminescent nanoscale lanthanum-based metal-organic framework (L-MOF)-armored single-stranded DNA antibody (MOF-armored-anti-DNA antibody) as signal tags and aptamer bound to magnetic beads (Apt-MB) as capture probe. The reusable aptasensor combines signal tag and capture probe with antigen-antibody interaction. When the reusable aptasensor is formed, the strong fluorescence intensity of L-MOF will "turn off" by photo-induced electron transfer from excited states to an unfilled d shell of iron cations on the nanoparticle surface. Upon the presence of Aß oligomers in serum samples, they can be especially distinguished with the Aß oligomers aptamer in capture probes and then signal tags are released into the solution for developing the fluorescence aptasensor under excitation/emission 365 nm/430 nm. Meanwhile, the aptamer was recovered from the complex of Aß oligomers/Apt-MB by heat treatment. When the temperature returns to room temperature, the recovered aptamer in the capture probe can once again bound to the MOF-armored-anti-DNA antibody for reuse. The label-free reusable aptasensor system detection has high sensitivity and selectivity toward Aß oligomers (LOD = 0.4 pg/mL) and an excellent linear range (0.001-100 ng/mL). This strategy is a fruitful step for the development of reusable aptasensor and may turn on new avenues for the applications of Aß oligomer detection in clinical diagnosis.Graphical abstract.

A bispecific nanobody with high sensitivity/efficiency for simultaneous determination of carbaryl and its metabolite 1-naphthol in the soil and rice samples.

The simultaneous determination of carbaryl and its metabolite 1-naphthol is essential for risk assessment of pesticide exposure in agricultural and environmental samples. Herein, several bispecific nanobodies (BsNbs) with different lengths of hydrophilic linkers and junction sites were prepared and characterized for the simultaneous recognition of carbaryl and its metabolite 1-naphthol. It was found that the affinity of BsNbs to the analytes could be regulated by controlling linker length and linking terminal. Additionally, molecular simulation revealed that linker lengths affected the conformation of BsNbs, leading to alteration in sensitivity. The BsNb with G4S linker, named G4S-C-N-VHH, showing good thermal stability and sensitivity was used to develop a bispecific indirect competitive enzyme-linked immunosorbent assay (Bic-ELISA). The assay demonstrated a limit of detection of 0.8 ng/mL for carbaryl and 0.4 ng/mL for 1-naphthol in buffer system. Good recoveries from soil and rice samples were obtained, ranging from 80.0% to 112.7% (carbaryl) and 76.5%-110.8% (1-naphthol), respectively. Taken together, this study firstly provided a BsNb with high sensitivity and efficiency against environmental pesticide and its metabolite, and firstly used molecular dynamics simulation to explore the influence of linker on recognition. The results are valuable for the application of immunoassay with high efficiency in the fields of environment and agriculture.

Quantitative differentiation of malignant and benign thyroid nodules with multi-parameter diffusion-weighted imaging.

BACKGROUND: The value of conventional magnetic resonance imaging in the differential diagnosis of thyroid nodules is limited; however, the value of multi-parameter diffusion-weighted imaging (DWI) in the quantitative evaluation of thyroid nodules has not been well determined. AIM: To determine the utility of multi-parametric DWI including mono-exponential, bi-exponential, stretched exponential, and kurtosis models for the differentiation of thyroid lesions. METHODS: Seventy-nine patients (62 with benign and 17 with malignant nodules) underwent multi-b value diffusion-weighted imaging of the thyroid. Multiple DWI parameters were obtained for statistical analysis. RESULTS: Good agreement was found for diffusion parameters of thyroid nodules. Malignant lesions displayed lower diffusion parameters including apparent diffusion coefficient (ADC), the true diffusion coefficient (D), the perfusion fraction (f), the distributed diffusion coefficient (DDC), the intravoxel water diffusion heterogeneity (α) and kurtosis model-derived ADC (Dapp), and higher apparent diffusional kurtosis (Kapp) than benign entities (all P < 0.01), except for the pseudodiffusion coefficient (D*) (P > 0.05). The area under the ROC curve (AUC) of the ADC(0 and 1000) was not significantly different from that of the ADC(0 and 2000), ADC(0 to 2000), ADC(0 to 1000), D, DDC, Dapp and Kapp (all P > 0.05), but was significantly higher than the AUC of D*, f and α (all P < 0.05) for differentiating benign from malignant lesions. CONCLUSION: Multiple DWI parameters including ADC, D, f, DDC, α, Dapp and Kapp could discriminate benign and malignant thyroid nodules. The metrics including D, DDC, Dapp and Kapp provide additional information with similar diagnostic performance of ADC, combination of these metrics may contribute to differentiate benign and malignant thyroid nodules. The ADC calculated with higher b values may not lead to improved diagnostic performance.

Production and Characterization of Biotinylated Anti-fenitrothion Nanobodies and Development of Sensitive Fluoroimmunoassay.

A simple and sensitive fluoroimmunoassay (FIA) based on a heavy-chain antibody (VHH) for rapid detection of fenitrothion was developed. A VHH library was constructed from an immunized alpaca, and one clone recognizing fenitrothion (namely, VHHjd8) was achieved after careful biopanning. It was biotinylated by fusing with the Avi tag and biotin ligase to obtain a fusion protein (VHHjd8-BT), showing both binding capacity to fenitrothion and the streptavidin poly-horseradish peroxidase conjugate (SA-polyHRP). Based on a competitive assay format, the absorbance spectrum of oxidized 3,3',5,5'-tetramethylbenzidine generated by SA-polyHRP overlapped the emission spectrum of carbon dots, which resulted in quenching of signals due to the inner-filter effect. The developed FIA showed an IC50 value of 1.4 ng/mL and a limit of detection of 0.03 ng/mL, which exhibited 15-fold improvement compared with conventional enzyme-linked immunosorbent assay. The recovery test of FIA was validated by standard GC-MS/MS, and the results showed good consistency, indicating that the assay is an ideal tool for rapid screening of fenitrothion in bulk food samples.

[Relationship between epithelial-mesenchymal transition and basal cell-like phenotype in breast cancer].

OBJECTIVES: To evaluate the relationship between epithelial-mesenchymal transition and basal cell-like phenotype breast cancer (BLBC). METHODS: Three hundred and eighty two cases of breast cancers including basal cell-like, luminal A, luminal B and Her-2 subtypes were collected from 458 cases of invasive breast cancers based on their immunophenotypes. They were then stained immunohistochemically with FOXC-2, vimentin, Syndecan-1 and E-cadherin. The relationship of these markers with the basal cell-like phenotype of breast cancer was studied. RESULTS: Of the 41 BLBC cases, FOXC-2, vimentin and Syndecan-1 were positive in 14 cases (34.1%), 18 cases (43.9%) and 36 cases (87.7%) respectively; E-cadherin expression was reduced in 26 cases (63.4%). The positive rates of FOXC-2 and vimentin were higher in BLBC than in other subtypes of breast cancer (P < 0.01). The expression of E-cadherin was the lowest among the 4 subtypes of breast cancers (P < 0.01). Syndecan-1 was positive in the stromal cells adjacent to cancer cells in 17 cases (41.5%) BLBC and the expression was higher than that in other subtypes (P = 0.007). There existed a correlation between FOXC-2 and vimentin expression in BLBC (r = 0.607, P < 0.01). The rates of positive lymph nodes in FOXC-2 and vimentin positive BLBC cases were 71.4% and 66.7% respectively, and both were higher than those of FOXC-2 and vimentin negative BLBC cases (P = 0.002 and P = 0.001). CONCLUSION: Epithelial-mesenchymal transition is probably related to the basal cell-like phenotype of breast cancers, and this may be one of the reasons accounting for the different biological behavior of BLBC from other subtypes of breast cancer.

[Clinicopathologic characteristics of breast cancer with basal-like immunophenotype].

OBJECTIVE: To study the clinicopathologic characteristics of basal-like immunophenotype breast cancer (BLBC). METHODS: 458 cases of female infiltrative breast cancer were studied using immunohistochemical staining with an antibody panel of ER, PR, HER2, Ki-67, CK5/6, CK14 and epidermal growth factor receptor (EGFR) and were classified basing on the immunophenotypes. The clinicopathologic characteristics were compared with other immunophenotypes of breast cancer. 228 of 458 cases of breast cancer were followed up. RESULTS: 46 cases of BLBC were screened out among the 458 breast cancers. And histological features of BLBC were analysed including the larger diameter of cancer foci (average 3.3 cm), appearance of squeezing phenomenon of neighboring cell borders (58.7%, 27/46), geography-like distribution of necrosis (52.2%, 24/46), central zone fibrosis (30.4%, 14/46) and lymphoplasmacytic infiltration at the margin and stroma (63.0%, 29/46). There were nuclear pleomorphism with numerous mitoses. The cancer cells were closely arranged, forming irregular solid architectures. There was a high expression (> 25%) of Ki-67 (43.5%, 20/46). CK5/6, CK14 and EGFR were positive in 58.7% (27/46), 43.5% (20/46) and 65.2% (30/46) respectively. 3-year survival rate of BLBC was 66.9%, lower than the luminal A breast cancer and similar to HER2 over-expression breast cancer. CONCLUSIONS: The proportion of BLBC in the group of breast cancers is 10%. BLBC has its distinct histological and cytological features. Currently, it is still necessary to depend on immunophenotyping in making a BLBC diagnosis. BLBC is the one of breast cancer subtypes with the poorest prognosis.

Prognostic values of interim and post-therapy 18F-FDG PET/CT scanning in adult patients with Burkitt's lymphoma / 癌症

<p><b>BACKGROUND</b>The prognostic values of interim and post-therapy fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) scanning have been confirmed in several subtypes of lymphoma. However, its prognostic value in Burkitt's lymphoma has not been clearly defined. The aim of the present study was to assess the prognostic value of PET/CT scanning during different treatment processes of Burkitt's lymphoma.</p><p><b>METHODS</b>A total of 29 adult patients with newly diagnosed Burkitt's lymphoma were retrospectively involved in this study; of them, 23 patients underwent baseline PET/CT, 15 patients underwent mid-therapy PET/CT after 1-4 cycles of chemotherapy, and 17 patients underwent post-therapy PET/CT after all planned first-line chemotherapy cycles. Mid-therapy and post-therapy PET/CT results (positive vs. negative) were visually interpreted according to the criteria of the International Harmonization Project. The reduction in the maximum standardizes uptake values (∆SUVmax) of 25%, 50%, and 75% were regarded as cutoff points. Overall survival (OS) and progression-free survival (PFS) were regarded as the major endpoints.</p><p><b>RESULTS</b>The median OS and PFS were 27.6 months (range 6.5-78.3 months) and 27.2 months (range 3.0-78.3 months), respectively. The median SUVmax of the baseline PET/CT was 18.3 (range 1.6-35.9), whereas the median SUVmax of the mid-therapy and post-therapy PET/CT decreased to 4.0 (range 0-17.6) and 3.0 (range 0-14.5), respectively. The patients' Eastern Cooperative Oncology Group (ECOG) scores (<2 vs. ≥2) were significantly associated with the baseline PET/CT SUVmax. The mid-therapy and post-therapy PET/CT results (positive vs. negative) showed no significant association with OS or PFS. The optimal cutoff ∆SUVmax from the baseline to the post-therapy PET/CT that could predict a change in OS in patients with Burkitt's lymphoma was 50% (P = 0.019).</p><p><b>CONCLUSIONS</b>(18)F-FDG uptake was intense in Burkitt's lymphoma, and there was a significant reduction in SUVmax during the interim and post-therapy PET/CT procedures. A ∆SUVmax of greater than 50% was a favorable cutoff point to predict the OS of Burkitt's lymphoma patients.</p>