Characterization of Tetrodes Coated with Au Nanoparticles (AuNPs) and PEDOT and Their Application to Thalamic Neural Signal Detection in vivo

Tetrodes, consisting of four twisted micro-wires can simultaneously record the number of neurons in the brain. To improve the quality of neuronal activity detection, the tetrode tips should be modified to increase the surface area and lower the impedance properties. In this study, tetrode tips were modified by the electrodeposition of Au nanoparticles (AuNPs) and dextran (Dex) doped poly (3,4-ethylenedioxythiophene) (PEDOT). The electrochemical properties were measured using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A decrease in the impedance value from 4.3 MΩ to 13 kΩ at 1 kHz was achieved by the modified tetrodes. The cathodic charge storage capacity (CSC(C)) of AuNPs-PEDOT deposited tetrodes was 4.5 mC/cm², as determined by CV measurements. The tetrodes that were electroplated with AuNPs and PEDOT exhibited an increased surface area, which reduced the tetrode impedance. In vivo recording in the ventral posterior medial (VPM) nucleus of the thalamus was performed to investigate the single-unit activity in normal rats. To evaluate the recording performance of modified tetrodes, spontaneous spike signals were recorded. The values of the L-ratio, isolation distance and signal-to-noise (SNR) confirmed that electroplating the tetrode surface with AuNPs and PEDOT improved the recording performance, and these parameters could be used to effectively quantify the spikes of each cluster.

Identification of Enterovirus C105 for the first time in New Zealand

In this report we describe a new approach in HIV sentinel surveillance that was piloted in Viet Nam in 2009 and is currently being rolled out in all provinces. It comprises a brief behavioural questionnaire added to the HIV sentinel surveillance surveys conducted routinely among people who inject drugs, female sex workers and men who have sex with men. Timely reporting of data from this system has resulted in improvements to HIV prevention efforts for most at-risk populations.

Hepatitis B Screening and Vaccination Practices in Asian American Primary Care

BACKGROUND/AIMS: Screening for hepatitis B virus (HBV) is recommended in populations with anticipated prevalence > or =2%. This study surveyed HBV screening and vaccination practices of Asian American primary care providers (PCPs). METHODS: Approximately 15,000 PCPs with Asian surnames in the New York, Los Angeles, San Francisco, Houston, and Chicago areas were invited to participate in a web-based survey. Asian American PCPs with > or =25% Asian patients in their practice were eligible. RESULTS: Of 430 (2.9%) survey respondents, 217 completed the survey. Greater than 50% followed > or =200 Asian patients. Although 95% of PCPs claimed to have screened patients for HBV, 41% estimated that < or =25% of their adult Asian patients had ever been screened, and 50% did not routinely screen all Asian patients. In a multivariable analysis, the proportion of Asian patients in the practice, provider geographic origin and the number of liver cancers diagnosed in the preceding 12 months were significantly associated with a higher likelihood of screening for HBV. Over 80% of respondents reported that < or =50% of their adult Asian patients had received the HBV vaccine. CONCLUSIONS: Screening and vaccination for HBV in Asian American patients is inadequate. Measures to improve HBV knowledge and care by primary-care physicians are critically needed.