Sensitive colorimetric assay using insulin G-quadruplex aptamer arrays on DNA nanotubes coupled with magnetic nanoparticles.

Described here is a methodology for fabrication of a sensitive colorimetric nanoassay for measurement of insulin using G-quadruplex aptamer arrays on DNA nanotubes (DNTs) coupled with magnetic nanoparticles. The spectroscopic findings (e.g. visible spectra, velocity assay and limit of detection determination) indicated a highly sensitive performance of this new nanoassay in comparison to those results obtained from the insulin assay with non-arrayed aptamers. The clinical performance statistics (i.e. paired sample t-test, Bland-Altman plot and scatter diagram) from the newly developed assay and the enzyme-linked immunosorbent assay suggested its reliable precision and its acceptable repeatability for measurement of insulin in human sera. This is, to our knowledge, the first study for the application of magnetic nanoparticle-coupled DNTs for carrying G-quadruplex aptamers for detection of biomolecules (such as insulin) in human serum.

Stereological estimation of particle shape and orientation from volume tensors.

In the present paper, we describe new robust methods of estimating cell shape and orientation in 3D from sections. The descriptors of 3D cell shape and orientation are based on volume tensors which are used to construct an ellipsoid, the Miles ellipsoid, approximating the average cell shape and orientation in 3D. The estimators of volume tensors are based on observations in several optical planes through sampled cells. This type of geometric sampling design is known as the optical rotator. The statistical behaviour of the estimator of the Miles ellipsoid is studied under a flexible model for 3D cell shape and orientation. In a simulation study, the lengths of the axes of the Miles ellipsoid can be estimated with coefficients of variation of about 2% if 100 cells are sampled. Finally, we illustrate the use of the developed methods in an example, involving neurons in the medial prefrontal cortex of rat.

Detection and spatial characterization of minicolumnarity in the human cerebral cortex.

BACKGROUND: Spatial characterization of vertical organization of neurons in human cerebral cortex, cortical columnarity or minicolumns, and its possible association with various psychiatric and neurological diseases has been investigated for many years. NEW METHOD: In this study, we obtained 3D coordinates of disector sampled cells from layer III of Brodmann area 4 of the human cerebral cortex using light microscopy and 140-µm-thick glycolmethacrylate sections. A new analytical tool called cylindrical K-function was applied for spatial point pattern analysis of 3D datasets to see whether there is a spatially organized columnar structure. In order to demonstrate the behaviour of the cylindrical K-function, the result from brain tissues was compared with two models: A homogeneous Poisson process exhibiting complete spatial randomness, and a Poisson line cluster point process. The latter is a point process model in 3D space, which exhibits spatial structure of points similar to minicolumns. RESULTS: The data show in three out of four samples nonrandom patterns in the 3D neuronal positions with the direction of minicolumns perpendicular to the pial surface of the brain - without a priori assuming the existence of minicolumns. COMPARISON WITH EXISTING METHODS: Studies on columnarity are difficult and have mainly been based on two-dimensional images analysis of thin sections of the cerebral cortex with the a priori assumption that minicolumns existed. CONCLUSIONS: A clear difference from complete spatial randomness in the data could be detected with the new tool, the cylindrical K-function, although classical functional summary statistics are less useful in this connection.

Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model.

BACKGROUND: The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. MATERIALS AND METHODS: In this study that was aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted by a GSM mobile phone on the pattern of contraction in frog's isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz), pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. RESULTS: Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. CONCLUSION: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study.

INTRODUCTION: The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog's isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz). MATERIALS AND METHODS: Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF) radiation emitted from a common Jammer at a distance of 1m from the jammer's antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T), the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz) as stimuli. RESULTS: The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. CONCLUSION: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

Estimating the surface area of nonconvex particles from central planar sections.

In this paper, we present a new surface area estimator in local stereology. This new estimator is called the 'Morse-type surface area estimator' and is obtained using a two-stage sampling procedure. First a plane section through a fixed reference point of a three-dimensional structure is taken. In this section plane, a modification of the area tangent count method is used. The Morse-type estimator generalizes Cruz-Orive's pivotal estimator for convex objects to nonconvex objects. The advantages of the Morse-type estimator over existing local surface area estimators are illustrated in a simulation study. The Morse-type estimator is well suited for computer-assisted confocal microscopy and we demonstrate its practicability in a biological application: the surface area estimation of the nuclei of giant-cell glioblastoma from microscopy images. We also present an interactive software that allows the user to efficiently obtain the estimator.

Chemical and spatial analysis of protein loaded PLGA microspheres for drug delivery applications.

Polymer microspheres for controlled release of therapeutic protein from within an implantable scaffold were produced and analysed using complimentary techniques to probe the surface and bulk chemistry of the microspheres. Time of Flight - Secondary Ion Mass Spectrometry (ToF-SIMS) surface analysis revealed a thin discontinuous film of polyvinyl alcohol (PVA) surfactant (circa 4.5 nm thick) at the surface which was readily removed under sputtering with C(60). Atomic Force Microscopy (AFM) imaging of microspheres before and after sputtering confirmed that the PVA layer was removed after sputtering revealing poly(lactic-co-glycolic) acid(PLGA). Scanning electron microscopy showed the spheres to be smooth with some shallow and generally circular depressions, often with pores in their central region. The occurrence of the protein at the surface was limited to areas surrounding these surface pores. This surface protein distribution is believed to be related to a burst release of the protein on dissolution. Analysis of the bulk properties of the microspheres by confocal Raman mapping revealed the 3D distribution of the protein showing large voids within the pores. Protein was found to be adsorbed at the interface with the PLGA oil phase following deposition on evaporation of the solvent. Protein was also observed concentrated within pores measuring approximately 2 µm across. The presence of protein in large voids and concentrated pores was further scrutinised by ToF-SIMS of sectioned microspheres. This paper demonstrates that important information for optimisation of such complex bioformulations, including an understanding of the release profile can be revealed by complementary surface and bulk analysis allowing optimisation of the therapeutic effect of such formulations.

The Effect of Intra-CA1 Agmatine Microinjection on Water Maze Learning and Memory in Rat.

BACKGROUND: Reports on agmatine are controversial showing that it may improve memory, it can deteriorate memory and some did not notice any interference with learning and memory. In the present study, the effect of directly intra-CA1 agmatine microinjection on water maze learning and memory has been assessed. METHODS: The cannuls were implanted in hippocampal CA1 regions of rats in a sterotaxic frame after general anesthesia. After one week recovery period, the animals were assessed in the reference memory version of water maze. Agmatine (1, 10, 100 or 200 µg/0.5 µl) or saline were infused 20 minutes before or immediately after training. RESULTS: Agmatine-treated rats did not show any significant difference neither in water maze acquisition nor in consolidation task in comparison with control and sham groups. CONCLUSION: Agmatine does not affect water maze learning and memory.

Application of the UNIFAC model for prediction of surface tension and thickness of the surface layer in the binary mixtures.

Surface properties of binary mixtures of (alkanol with acetonitrile) have been measured by surface tension method at T=298.15 K and atmospheric pressure. The UNIFAC method is used for calculation activity coefficients of surface and bulk phases. Also, the surface tension has been predicted based on the Suarez method. This method combines a model for the description of surface tension of liquid mixtures with a UNIFAC group contribution method for the calculation of activity coefficient. Two techniques for calculation of molar surface areas, based on Paquette areas and Rasmussen areas are tested. On comparing the computed values of surface tension by the present approaches with experimental data, satisfactory results have been observed. In addition, the relative Gibbs adsorption and the surface mole fraction have been evaluated using this model. It is possible to calculate the thickness of liquid-vapor interfaces starting from surface tension data. A novel procedure is developed to obtain the thickness of liquid-vapor interfaces as a function of composition in binary systems.

Electrical stimulation of nucleus raphe dorsalis changes morphine self-administration and withdrawal symptoms in rats.

The involvement of antero-dorsal part of the nucleus raphe dorsalis (NRD) in motivational aspects of drug-taking behaviour during initiation of drug self-administration was investigated using a recently developed behavioural paradigm. In separate experiments animals were allowed to self-administer morphine (1 mg/kg per inf) ten consecutive daily 3-h sessions. During all morphine self-administration sessions lever-press behaviour was measured in absence of electrical stimulation of NRD, as an index of the motivational aspects involved in drug-taking behaviour. The electrical stimulation (pulse 0.5 ms, 150 &mgr;A, 20 Hz) of NRD 30 min before morphine self-administration produced a significant decrease in the initiation of morphine self-administration during all sessions (reduced number of lever-press behaviour). After the last test session, morphine withdrawal syndrome signs (wet dog shakes, jumping, writhing and diarrhoea) in the naloxone-induced behaviour were measured. Our results showed that these withdrawal syndrome signs decreased by application of electrical stimulation in NRD, in comparison with morphine groups. It is concluded that serotonergic system in the NRD might be involved in the motivational processes underlying morphine self-administration.