Tracking Cellular Functions by Exploiting the Paramagnetic Properties of X‐Nuclei

The term X‐nuclei summarises all nuclei (except protons) that occur in biological systems carrying a non‐zero nuclear spin. Significant involvement in physiological processes such as maintaining the transmembrane potential of living cells and energy metabolism make these nuclei highly interesting for nuclear magnetic resonance (NMR) experiments. In this chapter, a discussion of the basic physics of nuclei with a nuclear spin >1/2 is presented. On this basis, pulse sequences for the detection of multi quantum coherences (MQCs) are presented and explained. Information contained in the obtained MQC signal is linked to biophysical processes. Applications to study energy metabolism, oxygen consumption, and to track brain metabolites by means of X‐nuclei NMR are discussed as well as the use of functional phantoms, which can bridge the gap between basic biological research and NMR data interpretation

Cyclic strain upregulates VEGF and attenuates proliferation of vascular smooth muscle cells

OBJECTIVE:Vascular smooth muscle cell (VSMC) hypertrophy and proliferation occur in response to strain-induced local and systemic inflammatory cytokines and growth factors which may contribute to hypertension, atherosclerosis, and restenosis. We hypothesize VSMC strain, modeling normotensive arterial pressure waveforms in vitro, results in attenuated proliferative and increased hypertrophic responses 48 hrs post-strain.METHODS:Using Flexcell Bioflex Systems we determined the morphological, hyperplastic and hypertrophic responses of non-strained and biomechanically strained cultured rat A7R5 VSMC. We measured secretion of nitric oxide, key cytokine/growth factors and intracellular mediators involved in VSMC proliferation via fluorescence spectroscopy and protein microarrays. We also investigated the potential roles of VEGF on VSMC strain-induced proliferation.RESULTS:Protein microarrays revealed significant increases in VEGF secretion in response to 18 hours mechanical strain, a result that ELISA data corroborated. Apoptosis-inducing nitric oxide (NO) levels also increased 43% 48 hrs post-strain. Non-strained cells incubated with exogenous VEGF did not reproduce the antimitogenic effect. However, anti-VEGF reversed the antimitogenic effect of mechanical strain. Antibody microarrays of strained VSMC lysates revealed MEK1, MEK2, phospo-MEK1T385, T291, T298, phospho-Erk1/2T202+Y204/T185+T187, and PKC isoforms expression were universally increased, suggesting a proliferative/inflammatory signaling state. Conversely, VSMC strain decreased expression levels of Cdk1, Cdk2, Cdk4, and Cdk6 by 25-50% suggesting a partially inhibited proliferative signaling cascade.CONCLUSIONS:Subjecting VSMC to cyclic biomechanical strain in vitro promotes cell hypertrophy while attenuating cellular proliferation. We also report an upregulation of MEK and ERK activation suggestive of a proliferative phenotype. Hhowever, the proliferative response appears to be aborogated by enhanced antimitogenic cytokine VEGF, NO secretion and downregulation of Cdk expression. Although exogenous VEGF alone is not sufficient to promote the quiescent VSMC phenotype, we provide evidence suggesting that strain is a necessary component to induce VSMC response to the antimitogenic effects of VEGF. Taken together these data indicate that VEGF plays a critical role in mechanical strain-induced VSMC proliferation and vessel wall remodeling. Whether VEGF and/or NO inhibit signaling distal to Erk 1/2 is currently under investigation.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]

Electron interaction with domain walls in antiferromagnetically coupled multilayers

For antiferromagnetically coupled Fe/Cr multilayers the low field contribution to the resistivity, which is caused by the domain walls, is strongly enhanced at low temperatures. The low temperature resistivity varies according to a power law with the exponent about 0.7 to 1. This behavior can not be explained assuming ballistic electron transport through the domain walls. It is necessary to invoke the suppression of anti-localization effects (positive quantum correction to conductivity) by the nonuniform gauge fields caused by the domain walls.Comment: 5 pages with 3 figure

Spectral Imaging of Skin: Experimental Observations and Analyses

The emergence of compact optical spectral imaging technologies has motivated the study of their use in a variety of applications, including medical diagnosis and monitoring. In particular, large format CCD focal planes in conjunction with spectrally tunable devices offer enhanced spatial information together with visible and near infrared (NIR) spectroscopic data for the passive, noninvasive, measurement of human skin and near surface tissue characteristics. One such spectral imaging system was recently developed by mating a Liquid Crystal Tunable Filter (LCTF) together with a 2048x2048 silicon CCD focal plane. This system is capable of collecting more than 30 co-registered spectral images spaced every 10 nanometers and spanning 400 to 720 nanometers. This system combines the potential of near infrared diffuse reflectance spectroscopy with the high spatial resolution of traditional optical imaging techniques. Spectral images were acquired of portions of the hands and arms of several test subjects with a variety of features observable. The observations were collected in a light box under controlled illumination conditions. Images of a diffuse reflectance standard and instrument dark frames were collected to allow conversion of the raw images to spectral reflectance images. This paper presents examples of the spectral images collected, instrument characteristics and performance, and results of analysis algorithms applied to the data. Results also are shown for a new algorithm extracting the saturated oxygen hemoglobin fraction from these data

The Impact of Family-Based Interventions on Adolescent Glycemic Control: A Systematic Review of the Literature

poster abstractObjective: Glycemic control is a major source of family conflict among adolescents with type 1 diabetes and their parents. Family conflict is a determinant of how well adolescents will maintain glycemic control throughout adolescence; thus, family conflict resolution is a crucial step to managing their diagnosis. The purpose of this systematic review is to evaluate the effectiveness of family-based interventions on glycemic control of adolescents with type 1 diabetes. Methods: Databases utilized were Medline Ovid, PsycINFO, and Web of Science. Inclusion criteria for the studies selected included: peer-reviewed studies conducted in the United States; published between January 1994 to December 2014; and evaluated a family-based intervention’s effectiveness on adolescent diabetic glycemic control. Results: 11 studies met the criteria. Methods used to resolve family conflict included teamwork interventions, tailored interventions, behavioral family systems therapy, and family problem-solving management. Six studies did not show any significant influence on glycemic control. The only significant results on lowering glycemic control were found when a12-month follow-up was completed. Behavioral family systems therapy and family problem-solving management were found to be significant in improving adolescent glycemic control. Conclusion: It is crucial for healthcare providers to be aware of effective family-based interventions to help resolve family conflict and promote healthy glycemic control among adolescents with type 1 diabetes. Interventions specifically designed to address family conflict will not only foster healthy family relationships, but will target adolescents struggling to maintain adequate glycemic control. Results from this review shows that interventions based on family systems therapy and problem-solving management seem to be most effective. Future research is needed to replicate these findings in larger, more diverse samples

Spectral Imaging of Near-Surface Oxygen Saturation

A number of non invasive methods have been developed to characterize parameters in near-surface skin tissue; however, the work has usually been concerned with using either spectral or spatial information. This motivated our study in which both spatial and spectral data are used to extract features for characterizing the spatial distribution of near-surface oxygen saturation. This paper addresses combined physical and statistical models to retrieve the ratio of oxy- and deoxy-hemoglobin in tissues from data collected by an imaging spectrometer. To retrieve the oxygen saturation fraction from the data, algorithms from the literature using two or three wavelengths were compared to our new algorithm using the many more wavelengths (25 to 60) available in imaging spectrometer data, and noise reduction achieved through principal component transformations. In addition to the analysis of experimental spectral imagery, an oxygen saturation phantom of size 128x128 pixels was simulated. In the forward process, a reflectance image was constructed from an assumed oxygen saturation map and the absorption coefficients of oxy-hemoglobin, deoxy-hemoglobin, melanin and other chromophores. The reflectance data have 60 bands spanning 400 nm to 990 nm with 10 nm intervals in the spectral dimension. Varying amounts of white Gaussian noise was added to the reflectance data to simulate measurement errors in an actual experiment. In the backward process, an oxygen saturation image was reconstructed by applying the algorithm to study the effect of measurement error on the retrieved saturation fraction. The resultant images were evaluated by their mean squared error

Intracellular sodium changes in cancer cells using a microcavity array-based bioreactor system and sodium triple-quantum mr signal

The sodium triple-quantum (TQ) magnetic resonance (MR) signal created by interactions of sodium ions with macromolecules has been demonstrated to be a valuable biomarker for cell viability. The aim of this study was to monitor a cellular response using the sodium TQ signal during inhibition of Na/K-ATPase in living cancer cells (HepG2). The cells were dynamically investigated after exposure to 1 mM ouabain or K$^{+}$-free medium for 60 min using an MR-compatible bioreactor system. An improved TQ time proportional phase incrementation (TQTPPI) pulse sequence with almost four times TQ signal-to-noise ratio (SNR) gain allowed for conducting experiments with 12–14 × 10$^{6}$ cells using a 9.4 T MR scanner. During cell intervention experiments, the sodium TQ signal increased to 138.9 ± 4.1% and 183.4 ± 8.9% for 1 mM ouabain (n = 3) and K$^{+}$-free medium (n = 3), respectively. During reperfusion with normal medium, the sodium TQ signal further increased to 169.2 ± 5.3% for the ouabain experiment, while it recovered to 128.5 ± 6.8% for the K$^{+}$-free experiment. These sodium TQ signal increases agree with an influx of sodium ions during Na/K-ATPase inhibition and hence a reduced cell viability. The improved TQ signal detection combined with this MR-compatible bioreactor system provides a capability to investigate the cellular response of a variety of cells using the sodium TQ MR signal

Removal of Spectro-Polarimetric Fringes by 2D Pattern Recognition

We present a pattern-recognition based approach to the problem of removal of polarized fringes from spectro-polarimetric data. We demonstrate that 2D Principal Component Analysis can be trained on a given spectro-polarimetric map in order to identify and isolate fringe structures from the spectra. This allows us in principle to reconstruct the data without the fringe component, providing an effective and clean solution to the problem. The results presented in this paper point in the direction of revising the way that science and calibration data should be planned for a typical spectro-polarimetric observing run.Comment: ApJ, in pres