An online spike detection and spike classification algorithm capable of instantaneous resolution of overlapping spikes

For the analysis of neuronal cooperativity, simultaneously recorded extracellular signals from neighboring neurons need to be sorted reliably by a spike sorting method. Many algorithms have been developed to this end, however, to date, none of them manages to fulfill a set of demanding requirements. In particular, it is desirable to have an algorithm that operates online, detects and classifies overlapping spikes in real time, and that adapts to non-stationary data. Here, we present a combined spike detection and classification algorithm, which explicitly addresses these issues. Our approach makes use of linear filters to find a new representation of the data and to optimally enhance the signal-to-noise ratio. We introduce a method called “Deconfusion” which de-correlates the filter outputs and provides source separation. Finally, a set of well-defined thresholds is applied and leads to simultaneous spike detection and spike classification. By incorporating a direct feedback, the algorithm adapts to non-stationary data and is, therefore, well suited for acute recordings. We evaluate our method on simulated and experimental data, including simultaneous intra/extra-cellular recordings made in slices of a rat cortex and recordings from the prefrontal cortex of awake behaving macaques. We compare the results to existing spike detection as well as spike sorting methods. We conclude that our algorithm meets all of the mentioned requirements and outperforms other methods under realistic signal-to-noise ratios and in the presence of overlapping spikes

IgG Responses to Anopheles gambiae Salivary Antigen gSG6 Detect Variation in Exposure to Malaria Vectors and Disease Risk

Assessment of exposure to malaria vectors is important to our understanding of spatial and temporal variations in disease transmission and facilitates the targeting and evaluation of control efforts. Recently, an immunogenic Anopheles gambiae salivary protein (gSG6) was identified and proposed as the basis of an immuno-assay determining exposure to Afrotropical malaria vectors. In the present study, IgG responses to gSG6 and 6 malaria antigens (CSP, AMA-1, MSP-1, MSP-3, GLURP R1, and GLURP R2) were compared to Anopheles exposure and malaria incidence in a cohort of children from Korogwe district, Tanzania, an area of moderate and heterogeneous malaria transmission. Anti-gSG6 responses above the threshold for seropositivity were detected in 15% (96/636) of the children, and were positively associated with geographical variations in Anopheles exposure (OR 1.25, CI 1.01–1.54, p = 0.04). Additionally, IgG responses to gSG6 in individual children showed a strong positive association with household level mosquito exposure. IgG levels for all antigens except AMA-1 were associated with the frequency of malaria episodes following sampling. gSG6 seropositivity was strongly positively associated with subsequent malaria incidence (test for trend p = 0.004), comparable to malaria antigens MSP-1 and GLURP R2. Our results show that the gSG6 assay is sensitive to micro-epidemiological variations in exposure to Anopheles mosquitoes, and provides a correlate of malaria risk that is unrelated to immune protection. While the technique requires further evaluation in a range of malaria endemic settings, our findings suggest that the gSG6 assay may have a role in the evaluation and planning of targeted and preventative anti-malaria interventions

Kinetics of electron transfer between metal hexacyanide complexes

The electron transfer reactions between three isomorphic hexacyanides complexes, Fe(CN)6 3- 4-, Os(CN)6 3- 4- and Ru(CN)6 3- 4- have been studied using the method of photoexcitation. The electron transfer rate constants between any two complexes increase by about a factor of 60 as the ionic strength is increased from 30 to 440 mM. An ionic-strength-independent reorganization energy of 1.1 eV was found for the hexacyanide self-exchange reaction when the data were analyzed according to the theory of Marcus. © 1990.link_to_subscribed_fulltex

Qualitative Detection of Proviral-DNA of HIV-1 In Infants To Determine The Efficacy of Antiretroviral Therapy In The Prevention of Vertical Transmission of HIV-1 In The Gambia

Background: The priority of the Gambia government is to eliminate maternal to child transmission of HIV and in line with this priority, the country implemented an antiretroviral therapy (ART) program. With this, all HIV infected pregnant and breastfeeding mothers and infants have access to ARV drugs. This study aims to determine the prevalence of vertical transmission of HIV among women receiving the ARV drugs. Methods: Dried blood spot samples were collected from 109 HIV-exposed infants enrolled in 13 PMTCT sites across the country. A qualitative detection of proviral-DNA of HIV-1 was performed using the Real Time Abbott PCR assay. Data from 105 mothers were analyzed using SPSS version 16.0 and association of risk factors to PCR results were analyzed using (Crosstabs) Pearson Chi-Square. The p-value of significant was set at p<0.05. Results: This study has found the prevalence of vertical transmission of HIV is 0.0% (0/64) among women that received the ARV prophylaxis then started ART, 7.1% (2/28) among mothers that received HIV prophylaxis only, and 38.4% (5/13) among women who neither receive HIV-prophylaxis nor ART during pregnancy or breastfeeding. Other risk factors of vertical transmission such as late initiation of treatment, default during treatment and first born of twins were found to be significantly associated with vertical transmission p=0.001, p=0.022 and p=0.000 respectively. Conclusion: This study has found that the early intervention of ART at the onset of pregnancy through breastfeeding can eliminates Maternal to Child transmission of HIV and a high risk of vertical transmission was found among women who neither receive prophylaxis nor ART. If the effectiveness of the antiretroviral therapy is maintain, the Gambia, in the near future will attain the WHO’s goal to eliminate Maternal to Child transmission of HIV