Recent Advances in DNA-Based Nanoprobes for In vivo MiRNA Imaging.

As a post transcriptional regulator of gene expression, microRNAs (miRNA) is closely related to many major human diseases, especially cancer. Therefore, its precise detection is very important for disease diagnosis and treatment. With the advancement of fluorescent dye and imaging technology, the focus has shifted from in vitro miRNA detection to in vivo miRNA imaging. This concept review summarizes signal amplification strategies including DNAzyme catalytic reaction, hybrid chain reaction (HCR), catalytic hairpin assembly (CHA) to enhance detection signal of lowly expressed miRNAs; external stimuli of ultraviolet (UV) light or near-infrared region (NIR) light, and internal stimuli such as adenosine triphosphate (ATP), glutathione (GSH), protease and cell membrane protein to prevent nonspecific activation for the avoidance of false positive signal; and the development of fluorescent probes with emission in NIR for in vivo miRNA imaging; as well as rare earth nanoparticle based the second near-infrared window (NIR-II) nanoprobes with excellent tissue penetration and depth for in vivo miRNA imaging. The concept review also indicated current challenges for in vivo miRNA imaging including the dynamic monitoring of miRNA expression change and simultaneous in vivo imaging of multiple miRNAs.

A NIR Programmable In Vivo miRNA Magnifier for NIR-II Imaging of Early Stage Cancer.

Aberrant expressions of biomolecules occur much earlier than tumor visualized size and morphology change, but their common measurement strategies such as biopsy suffer from invasive sampling process. In vivo imaging of slight biomolecule expression difference is urgently needed for early cancer detection. Fluorescence of rare earth nanoparticles (RENPs) in second near-infrared (NIR-II) region makes them appropriate tool for in vivo imaging. However, the incapacity to couple with signal amplification strategies, especially programmable signal amplification strategies, limited their application in lowly expressed biomarkers imaging. Here we develop a 980/808 nm NIR programmed in vivo microRNAs (miRNAs) magnifier by conjugating activatable DNAzyme walker set to RENPs, which achieves more effective NIR-II imaging of early stage tumor than size monitoring imaging technique. Dye FD1080 (FD1080) modified substrate DNA quenches NIR-II downconversion emission of RENPs under 808 nm excitation. The miRNA recognition region in DNAzyme walker is sealed by a photo-cleavable strand to avoid "false positive" signal in systemic circulation. Upconversion emission of RENPs under 980 nm irradiation activates DNAzyme walker for miRNA recognition and amplifies NIR-II fluorescence recovery of RENPs via DNAzyme catalytic reaction to achieve in vivo miRNA imaging. This strategy demonstrates good application potential in the field of early cancer detection.

Cooperatively enhanced photothermal-chemotherapy via simultaneously downregulating HSPs and promoting DNA alkylation in cancer cells.

Photothermal therapy (PTT) has emerged as one of the important strategies for cancer treatment due to its precision and no drug resistance. However, upregulation of heat shock protein (HSP) expression during PTT severely limits its overall therapeutic effect. Accordingly, in this study, we developed a new anticancer strategy based on an l-glutathione (GSH)-activated prodrug (Cy-S-S-Cbl), which consisted of an alkylating reagent (Cbl) covalently linked to a photothermal photosensitizer (Cy7), to achieve cooperatively enhanced photothermal-chemotherapy. In the presence of overexpressed GSH in cancer cells, Cy-S-S-Cbl was converted into Cy-NH2 to achieve photothermal effect enhancement by the photo-induced electron transfer (PET) effect and release the alkylation reagent. Meanwhile, the photothermal effect of Cy-NH2 enhanced the DNA alkylation of chemotherapy drugs. Surprisingly, we first found that the therapeutic efficacy of PTT was improved owing to the down-regulation of heat shock protein 70 (HSP70) by chemotherapy. The two treatments had a synergistic promotion effect achieving higher cancer cell killing efficiency. Under 808 nm light irradiation, Cy-S-S-Cbl could effectively realize selective killing of cancer cells and tumor growth inhibition. Therefore, we strongly believe that this efficient cooperative design strategy will provide a new idea to improve the treatment efficiency of prodrugs.

Immune response to hepatitis B vaccine with high antigen content in non-responders after standard primary vaccination in Chinese adults.

CONTEXT: Alternative schedules are needed to provide greater immunogenicity in adults who fail to respond to the standard hepatitis B (HB) vaccine regimen. OBJECTIVE: To evaluate the immunogenicity and safety of high antigen content HB vaccine formulations administered to non-responders after routine primary vaccination. DESIGN SETTING, AND PARTICIPANTS: This was a phase III, double-blind, controlled clinical trial in China. We enrolled healthy participants (16-60 years old) seronegative for HB surface (HBs) antigen after primary vaccination, who had HBs antibody (anti-HBs) titres <10 mIU/ml at 28 days following routine vaccination with licensed HB vaccine containing 10 µg of antigen. Participants were randomised (2:2:1) to receive three booster doses of HB vaccine formulations containing 60 µg, 30 µg or 10 µg of antigen per dose 28 days apart. Blood samples were obtained pre-vaccination and 28 days after each dose to assess immunogenicity. Reactogenicity and safety were evaluated up to 28 days after each vaccine dose. RESULTS: Seroconversion rates were ≥ 92.1% and ≥ 87.1% as from the second dose of the 60 µg and 30 µg HB vaccine formulations, respectively, with geometric mean concentrations (GMCs) of ≥ 286.0 mIU/ml and ≥ 164.0 mIU/ml. In the 10 µg HB vaccine group the seroconversion rates were ≥ 83.0% and the GMCs ≥ 110.1 mIU/ml as from the second vaccine dose. All HB vaccine formulations were well tolerated: 352/1091 (32.3%) participants reported at least one injection-site or systemic adverse reaction (145/434 [33.4%] from the 60µg group; 138/435 [31.7%] from the 30 µg group and 69/222 [31.1%] from the 10 µg group). Most reactions were mild or moderate and resolved within 24h. No serious adverse events were reported. CONCLUSION: Booster vaccination with a three-dose schedule of a high antigen content HB vaccine formulation was immunogenic and well tolerated in healthy adults. Clinicaltrialsgov Identifier: NCT01203319.

Retrospective study of the incidence of HFMD and seroepidemiology of antibodies against EV71 and CoxA16 in prenatal women and their infants.

BACKGROUND: Hand, foot, and mouth disease (HFMD) has been emerging as an important public problem over the past few decades, especially in Asian and Pacific regions. A national program on EV71 vaccine development against HFMD was initiated in China, in 2008, which called for a need for seroepidemiological study for the target population. METHODOLOGY/PRINCIPAL FINDINGS: This was a retrospective study conducted in Jiangsu Province, in October, 2010. We measured the neutralizing antibodies against EV71 and CoxA16 in a cohort of infants aged of 2, 7, 12, and 27-38 months and their mothers just before delivery. Series sera samples from 975 infants and 555 mothers were collected and analyzed. Questionnaires on the history of HFMD were completed in the survey. A total of 143 HFMD cases were collected, but only 11.2% were reported to the National Infectious Disease Information Management System. The level of maternal antibody titers decreased dramatically during the first 7 month and remained at a relatively low level thereafter. But it increased significantly from month 12 to months 27-38. The accumulate incidence density of HFMD demonstrated a significant increase after 14 months of age, resulting in a accumulate incidence density of 50.8/1000 person-years in survey period. Seropositivity of EV71 antibody in infants at the age of 2 months seems to demonstrate a protective effect against HFMD. CONCLUSIONS AND SIGNIFICANCE: High seropositive rate of EV71 and CoxA16 antibody was found in prenatal women in mainland China, and there is a need to enhance the HFMD case management and the current surveillance system. We suggest that infants aged between 6 to 14 months should have the first priority to receive EV71 vaccine.

[Influence of hydrogen sulfide on important organs in rats with severe burn].

OBJECTIVE: To investigate the changes in hydrogen sulfide (H2S) and cystathionine gamma-lyase (CSE) in rats with severe burn, and to analyze the effects on important organs. METHODS: One hundred and four healthy male SD rats were divided into normal control group (NC, n = 8), burn group (B, n = 48), and H2S intervention group (HI, n = 48) according to the random number table. SD rats in HI group were intraperitoneally injected with NaHS (56 micromol/kg) once a day for 5 days. Then rats in HI and B groups were subjected to 30% TBSA full-thickness burn. Blood sample as well as heart, liver, lung, kidney, and stomach tissue samples were harvested from rats in B group at post burn hour (PBH) 2, 6, 12, 24, 48, and 96 respectively for determination of serum content of H2S and CSE activity. Serum content of alanine transaminase (ALT), aspartate aminotransferase (AST), MB isoenzyme of creatine kinase (CK-MB), urea nitrogen (BUN), and creatinine (Cr) in HI and B groups were examined at each time point. Samples were harvested from above organs in each group for histomorphological observation. Above-mentioned indexes were also determined in NC group as control. Data were processed with SNK- q test, t test, correlation analysis (between serum content of H2S and CSE activities, biochemical indexes). RESULTS: Serum content of H2S and CSE activities of above organs (except for lung tissue at PBH 48, 96) in B group within PBH 96 were lower than those in NC group, reaching minimum values at PBH 6 or 12. Compared with those in NC group, serum contents of all biochemical indexes in B group were obviously increased within PBH 48, in which serum contents of BUN [(32.5 +/- 9.8) mmol/L] and Cr [(65 +/- 9) micromol/L] reached peak at PBH 6, and serum contents of ALT [(423 +/- 59) U/L], AST [(993 +/- 60) U/L], and CK-MB [(49 261 +/- 6637) U/L] peaked at PBH 12. Serum contents of all biochemical indexes in HI group at each time point were significantly decreased as compared with those in B group, but the same change tendencies were showed in both groups. Histomorphological observation showed that all the organs were severely injured in B group at PBH 24, whereas those in HI group were markedly ameliorated. Serum content of H2S in B group was respectively correlated with CSE activities of all organs (with r value from 0.639 to 0.894, P values all below 0.005) and serum contents of biochemical indexes (with r value from 0.301 to 0.585, P values all below 0.001). CONCLUSIONS: H2S/CSE system may take part in pathophysiological process in rats with severe burn. Exogenous H2S replacement therapy can protect important organs of rats with severe burn.

Study on programmed cell death and dynamic changes of starch accumulation in pericarp cells of Triticum aestivum L.

Features of programmed cell death (PCD) and dynamic changes of starch accumulation in developing pericarp cells of wheat (Triticum aestivum L.) were observed and analyzed by periodic acid-Schiff/toluidine blue O double staining, fluorescence staining, terminal deoxynucleotidyl transferase-mediated fluorescein deoxyuridine triphosphate nick-end labeling (TUNEL) and transmission electron microscopy. The results showed that cellular organelles were orderly disintegrated. TUNEL-positive nuclei were detected at 0 day after flowering (DAF), whereas nuclei showed significant features of degradation at 2 DAF, such as chromatin condensation, nuclei condensation, and nuclei deformation. Then, heterochromatin gradually disappeared and the cellular nucleus was completely degraded. The mitochondria degradation and vacuolation also were detected at 15 DAF. These results indicated that the development of pericarp cells was a typical process of PCD. However, the PCD in pericarp cells had their own characteristics: PCD started early and lasted for a considerable time. In the delayed process of PCD, starch granules were synthesized, deposited, and degraded temporarily in amyloplasts or chloroplasts. The delay of PCD in pericarp cells may be due to sufficient photosynthetic assimilates and energy supply. Besides, normal mitochondria were required for pericarp cells to survive. Pericarp cells contained only compound starch granules. Starch was massively synthesized from 0 to 11 DAF, but it was rapidly degraded after 11 DAF. Therefore, apart from protection, pericarp cells played essential roles in starch synthesis, storage, and degradation, as well as nutrient transportation.

Evidence of ceased programmed cell death in metaphloem sieve elements in the developing caryopsis of Triticum aestivum L.

Transmission electron microscopy (TEM) and fluorescence microscopy studies revealed that the metaphloem sieve elements (MSEs) in the ventral vascular bundle of the caryopses of developing wheat (Triticum aestivum L.) undergo a unique type of programmed cell death (PCD). Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive nuclei were observed at 3 and 4 days after flowering (DAF). Transmission electron microscopy studies of differentiating MSEs revealed increased vacuolation, nuclear degeneration, chromatin condensation and localization to the periphery of the nucleus, and partly dilated perinuclear spaces, all typical characteristics of PCD in plant cells. In addition, vacuoles were disrupted at the last stages of differentiation. These results demonstrate that MSE differentiation is a unique type of PCD with highly selective autophagic processes, in which PCD ceases just prior to death. During this cessation of PCD, vacuoles and the endoplasmic reticulum appear to be associated with selective organelle digestion.