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Electrochemical sensors now play an important role in analysis and detection of nucleic acids. In this work, we present a novel double-signal technique for electrochemically measuring the sequence and length of the d(CAG) n repeat. The double-signal technique used an electrochemical molecular beacon (a hairpin DNA labeled with ferrocene), which was directly modified on the surface of a gold electrode, while a reporter probe (a DNA sequence labeled with horseradish peroxidase) was hybridized to the target DNA. First a simple single-signal sensor was characterized in which d(CAG) n repeats were detected using a short reporter DNA strand labeled with horseradish peroxidase. To obtain a reliable signal that was dependent on repeat number, a double-signal biosensor was created in which the single strand capture DNA in single-signal sensor was replaced by an electrochemical molecular beacon labeled with ferrocene. When the hairpin DNA hybridized to the target-reporter DNA complex, it opened, resulting in a decreased ferrocene current. Both electrochemical biosensors exhibited high selectivity and sensitivity with low detection limits of 0.21 and 0.15 pM, respectively, for the detection of d(CAG) n repeats. The double-signal sensor was more accurate for the determination of repeat length, which was measured from the ratio of signals for HRP and ferrocene (H/F). A linear relationship was found between H/F and the number of repeats (n), H/F = 0.1398n + 9.89788, with a correlation coefficient of 0.974. Only 10 nM of target DNA was required for measurements based on the value of H/F in the double-signal technique. These results indicated that this new double-signal electrochemical sensor provided a reliable method for the analysis of CAG trinucleotide repeats.

A neonatal rat model with hypoxic ischemic brain damage (HIBD) was established. Forty 7-day-old neonatal Wistar rats were randomly divided into four groups: sham operation, model, progesterone and Akt inhibitor. Electron microscopy revealed that the neonatal rats with HIBD showed neuronal changes. The protein expression levels of pAkt, Nuclear factor κB (NF-κB) and Bcl-2 in the hippocampus were detected by immunohistochemistry and Western blot. The neuronal structure was normal in the sham operation group after HIBD for 24 h. Cavitation change due to hypoxic ischemic brain damage was observed in the neurons of the model group. Progesterone treatment improved neuronal damage and cavitation. Neuronal cavitation was clearly changed in the Akt inhibitor group. The protein expression levels of hippocampal pAkt and Bcl-2 did not significantly change after HIBD, whereas that of NF-κB increased. Progesterone pre-treatment increased the expression levels of pAkt and Bcl-2 but decreased that of NF-κB. The protein expression levels of pAkt and Bcl-2 decreased in the Akt inhibitor group, whereas that of NF-κB increased. This result indicates that progesterone can decrease inflammation in HIBD, inhibit apoptosis and protect the brain by activating the Phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signalling pathway.

The satellite fault diagnosis has an important role in enhancing the safety, reliability, and availability of the satellite system. However, the problem of enormous parameters and multiple faults makes a challenge to the satellite fault diagnosis. The interactions between parameters and misclassifications from multiple faults will increase the false alarm rate and the false negative rate. On the other hand, for each satellite fault, there is not enough fault data for training. To most of the classification algorithms, it will degrade the performance of model. In this paper, we proposed an improving SVM based on a hybrid voting mechanism (HVM-SVM) to deal with the problem of enormous parameters, multiple faults, and small samples. Many experimental results show that the accuracy of fault diagnosis using HVM-SVM is improved.