Comparative Study of the Antioxidant Activity of Holarrhena Floribunda and Picralima Nitida

Picralima nitida (Stapf) T.Durand & H.Durand and Holarrhena floribunda (G.Don) T.Durand & Schinz are West and Central African plant species belonging to the Apocynaceae family. These two plants are used in traditional Ivorian medicine to treat hypertension, urinary tract infections, diarrhea, gonorrhea, malaria and diabetes. Phytochemical screening and evaluation of antioxidant activity of P. nitida fruit and H. floribunda leaf extracts of each of these two species have already been performed. In the present study, a comparative evaluation of the antioxidant activity of fruit (P. nitida) and leaf (H. floribunda) decoctions was carried out. The decoctions of P. nitida fruits and H. floribunda leaves were rich in secondary metabolites, especially polyphenols which have good antioxidant activity. Quantification of total phenols and flavonoids gave respective values of QP = 15235.632 ± 622 µg GAE / g dry matter and FP = 2.387 ± 0.387% for P. nitida and QH = 68597.701 ± 3171 µg GAE / g dry matter and FH = 17.581 ± 0.379% for H. floribunda. P. nitida showed antioxidant activity against DPPH radical (IC50 = 104.30 ± 3.17 μg / mL) and ferric ion Fe3 + (261.4 ± 36. 87 μmoL Eq Trolox / g extract). H. floribunda showed antioxidant activity against DPPH radical (IC50 = 41.73 ± 0.29 μg / mL) and ferric ion Fe3 + (365 ± 20.36 μmol Eq Trolox / g ExS).

Assessment of Mouse-Specific Pharmacokinetics in Kidneys Based on 131I Activity Measurements Using Micro-SPECT

Background In order to acquire accurate drug pharmacokinetic information, such as that required for tissue dosimetry, micro-SPECT must be quantitative and allow an accurate assessment of radioligand activity in the relevant tissue. This study investigates the feasibility of deriving accurate mouse-specific time-integrated drug pharmacokinetic data in mouse kidneys from activity measurements using micro-SPECT. Methods An animal experiment was done to evaluate the accuracy of 131I activity quantification in mouse kidneys using a micro-SPECT system against conventional ex vivo gamma counting (GC) in a NaI(Tl) detector. The imaging setting investigated was that of the mouse biodistribution of a 131I-labelled single-domain antibody fragment (sdAb) currently being investigated for targeted radionuclide therapy of HER2-expressing cancer. SPECT imaging of 131I 365-keV photons was done with a VECTor/CT system (MILabs, Netherlands) using a high-energy mouse collimator with 1.6-mm-diameter pinholes. For each activity quantification technique, the pharmacokinetic profile from approximately 1 to 73 h p.i. of the radioligand was derived and the time-integrated activity coefficient per gram of tissue (ã/M) was estimated. Additionally, SPECT activity recovery coefficients were determined in a phantom setting. Results SPECT activities underestimate the reference activities by an amount that is dependent on the 131I activity concentration in the kidney, and thus on the time point of the pharmacokinetic profile. This underestimation is around − 12% at 1.5 h (2.78 MBq.mL− 1 mean reference activity concentration), -13% at 6.6 h (143 kBq.mL− 1), -40% at 24 h (15 kBq.mL− 1) and − 46% at 73 h (5 kBq.mL− 1) p.i. The ã/M value estimated from SPECT activities is, nevertheless, within − 15% from the reference (GC) ã/M value. Furthermore, better quantitative accuracy (within 2% from GC) in the SPECT ã/M value is achieved when SPECT activities are compensated for partial recovery with a phantom-based correction factor. Conclusion The SPECT imaging system used, together with a robust activity quantification methodology, allows an accurate estimation of time-integrated pharmacokinetic information of the 131I-labelled sdAb in mouse kidneys. This opens the possibility to perform mouse-specific kidney-tissue dosimetry based on pharmacokinetic data acquired in vivo on the same mice used in nephrotoxicity studies.

Modeling of Activity-Induced Changes in Signal Propagation Speed of Mechano-Electrically Stimulated Nerve Fiber

One of the important questions in the research on neural coding is how the preceding axonal activity affects the signal propagation speed of the following one. We present an approach to solving this problem by introducing a multi-level spike count for activity quantification and fitting a family of linear regression models to the data. The best-achieved score is R2=0.89 and the comparison of different models indicates the importance of long and very short nerve fiber memory. Further studies are required to understand the complex axonal mechanisms responsible for the discovered phenomena.

Wearable Based Calibration of Contactless In-home Motion Sensors for Physical Activity Monitoring in Community-Dwelling Older Adults

Passive infrared motion sensors are commonly used in telemonitoring applications to monitor older community-dwelling adults at risk. One possible use case is quantification of in-home physical activity, a key factor and potential digital biomarker for healthy and independent aging. A major disadvantage of passive infrared sensors is their lack of performance and comparability in physical activity quantification. In this work, we calibrate passive infrared motion sensors for in-home physical activity quantification with simultaneously acquired data from wearable accelerometers and use the data to find a suitable correlation between in-home and out-of-home physical activity. We use data from 20 community-dwelling older adults that were simultaneously provided with wireless passive infrared motion sensors in their homes, and a wearable accelerometer for at least 60 days. We applied multiple calibration algorithms and evaluated results based on several statistical and clinical metrics. We found that using even relatively small amounts of wearable based ground-truth data over 7–14 days, passive infrared based wireless sensor systems can be calibrated to give largely better estimates of older adults' daily physical activity. This increase in performance translates directly to stronger correlations of measured physical activity levels with a variety of age relevant health indicators and outcomes known to be associated with physical activity.

Revisiting the fundamentals of p-nitrophenol analysis for its application in the quantification of lipases activity. A graphical update.

p-Nitrophenol (pNP) is a widely used compound for analytical determinations of several esterases (EC. 3.1.1.X), including lipases (E.C. 3.1.1.3). Most enzymatic measurements employ pNP derivatives such as esters, which are broken down by enzymatic hydrolysis, releasing pNP that is quantified by its absorbance at 410 nm. Although this type of methods was developed a few decades ago, the spectrophotometric analysis of pNP requires analytical measurements of pH and temperature to achieve reliable determinations. The aim of this paper is to offer a graphical update of how pH and temperature affect the p-nitrophenol absorbance at different wavelengths in lipase emulsified media, due to its relevance for the quantitative determination of lipase activity using spectrophotometric methods. To highlight the importance of each variable involved in this analysis, we dissolved pNP in emulsified media (for lipase activity quantification) at several pH values from 4.00 to 11.00, and measured its absorbance in a range of 270 nm – 500 nm and at several temperatures from 25°C to 50°C. The absorption patterns of pNP under the established conditions were graphed in 3D plots. The constructed 3D plots showed that, regardless of the temperature, below pH 6.00, pNP predominantly absorbs at 317 nm, due to the greater abundance of its protonated form, which is completely predominant at pH 3.50 and below. On the other hand, at pH 10.0 and above, the major absorption occurs at about 401 nm, confirming that the equilibrium is completely shifted to the pNP anionic form. These results also indicate that close to neutral pH value pNP, it displays a temperature dependence effect, increasing absorbance to 410 nm at higher temperatures. Due to many analytical determinations of enzymatic activities, the release of pNP is carried around pH 7.00. It is necessary to consider the determinant role of both pH and temperature over these measurements, how these variables must be strictly controlled, and how the calibration curves and blanks should take the reaction media pH and temperature into account.