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light sense [keywords]
- Revealing the Structure of Stereociliary Actin by X-Ray Nano-Imaging. [JOURNAL ARTICLE]
- ACS Nano 2014 Nov 21.
Hair cell stereocilia are crucial for hearing and the sense of balance. They include an array of accurately packed, parallel actin filaments and act as levers, which transform mechanical deformation into neuronal signals. The length of vestibular stereocilia reaches several micrometers, whereas, for individual microfilaments, the diameter and thereby the characteristic length scale in lateral direction is on the order of a few nanometers. This order of magnitude renders X-rays an ideal tool for investigating actin packing and numerous studies on reconstituted in vitro systems have revealed important information. Here we report on the characterization of intact stereocilia using two nanoscale X-ray techniques. We use X-ray ptychography to image stereocilia with quantitative phase contrast and high dose efficiency, showing stereocilia with diameters and lengths in the expected range. We further employ X-ray nanodiffraction using a nano-focused X-ray beam on the same order of magnitude as the width of a stereocilium. Despite the small probe volume we can clearly visualize the stereocilia bundles. From the individual diffraction patterns we determine the local orientation of the actin structures and can clearly correlate them with the corresponding visible-light fluorescence images. Furthermore, azimuthal integration of individual diffraction patterns reveals distinct intensity curves, showing distinct modulations of the signal, which reflect the relevant length scales and pronounced order in the biological system. The applied techniques are not limited to the studies on stereocilia but have the potential of being applied to many biological and soft-matter systems, in particular if a pronounced degree of order is present.
- Auditory learning through active engagement with sound: biological impact of community music lessons in at-risk children. [JOURNAL ARTICLE]
- Front Neurosci 2014.:351.
The young nervous system is primed for sensory learning, facilitating the acquisition of language and communication skills. Social and linguistic impoverishment can limit these learning opportunities, eventually leading to language-related challenges such as poor reading. Music training offers a promising auditory learning strategy by directing attention to meaningful acoustic elements of the soundscape. In light of evidence that music training improves auditory skills and their neural substrates, there are increasing efforts to enact community-based programs to provide music instruction to at-risk children. Harmony Project is a community foundation that has provided free music instruction to over 1000 children from Los Angeles gang-reduction zones over the past decade. We conducted an independent evaluation of biological effects of participating in Harmony Project by following a cohort of children for 1 year. Here we focus on a comparison between students who actively engaged with sound through instrumental music training vs. students who took music appreciation classes. All children began with an introductory music appreciation class, but midway through the year half of the children transitioned to the instrumental training. After the year of training, the children who actively engaged with sound through instrumental music training had faster and more robust neural processing of speech than the children who stayed in the music appreciation class, observed in neural responses to a speech sound /d/. The neurophysiological measures found to be enhanced in the instrumentally-trained children have been previously linked to reading ability, suggesting a gain in neural processes important for literacy stemming from active auditory learning. Despite intrinsic constraints on our study imposed by a community setting, these findings speak to the potential of active engagement with sound (i.e., music-making) to engender experience-dependent neuroplasticity and may inform the development of strategies for auditory learning.
- Phototherapy with combination of super-pulsed laser and light-emitting diodes is beneficial in improvement of muscular performance (strength and muscular endurance), dyspnea, and fatigue sensation in patients with chronic obstructive pulmonary disease. [JOURNAL ARTICLE]
- Lasers Med Sci 2014 Nov 21.
Phototherapy is an electrophysical intervention being considered for the retardation of peripheral muscular fatigue usually observed in chronic obstructive pulmonary disease (COPD). The objective of this study was to evaluate the acute effects of combination of super-pulsed laser and light-emitting diodes phototherapy on isokinetic performance in patients with COPD. Thirteen patients performed muscular endurance tests in an isokinetic dynamometer. The maximum voluntary isometric contraction (MVIC), peak torque (PT), and total work (TW) of the non-dominant lower limb were measured in two visits. The application of phototherapy or placebo (PL) was conducted randomly in six locations of femoral quadriceps muscle by using a cluster of 12 diodes (4 of 905 nm super-pulsed lasers, 0.3125 mW each; 4 of 875 nm LEDs, 17.5 mW each; and 4 of 640 nm LEDs, 15 mW each, manufactured by Multi Radiance Medical™). We found statistically significant increases for PT (174.7 ± 35.7 N · m vs. 155.8 ± 23.3 N · m, p = 0.003) and TW after application of phototherapy when compared to placebo (778.0 ± 221.1 J vs. 696.3 ± 146.8 J, p = 0.005). Significant differences were also found for MVIC (104.8 ± 26.0 N · m vs. 87.2 ± 24.0 N · m, p = 0.000), sensation of dyspnea (1 [0-4] vs. 3 [0-6], p = 0.003), and fatigue in the lower limbs (2 [0-5] vs. 5 [0.5-9], p = 0.002) in favor of phototherapy. We conclude that the combination of super-pulsed lasers and LEDs administered to the femoral quadriceps muscle of patients with COPD increased the PT by 20.2 % and the TW by 12 %. Phototherapy with a combination of super-pulsed lasers and LEDs prior to exercise also led to decreased sensation of dyspnea and fatigue in the lower limbs in patients with COPD.
- Assembly Modulation of PDI Derivative as a Supramolecular Fluorescence Switching Probe for Detection of Cationic Surfactant and Metal ions in Aqueous Media. [JOURNAL ARTICLE]
- ACS Appl Mater Interfaces 2014 Nov 18.
We report an amphiphilic perylene diimide (1), a bimolecular analog of L-3,4-dihydroxyphenylalanine (L-DOPA) as a reversible fluorescence switching probe for the detection and sensing of cationic surfactant and Fe3+/Cu2+ in an aqueous media respectively by means of host-guest interactions driven assembly and disassembly of 1. Photophysical studies of 1, going from DMSO (State-I) to pure aqueous medium (State-II) suggested the formation of self-assembled aggregates by displaying very weak fluorescence emission along with red shifted broad absorption bands. Interestingly, cationic surfactant cetyltrimethylammonium bromide (CTAB) could disassemble 1 in miceller conditions by restoring bright yellow fluorescence and vibronically well-defined (Frank-Condom progressions A0-0/A0-1 ≈ 1.6) absorption bands of 1 over other neutral and anionic surfactants (State-III). Owing to metal chelating nature of L-DOPA, 1 was able to sense Fe3+ and Cu2+ among the pool of other metal ions by means of fluorescence switching off state, attributed to metal interaction driven assembly of 1 (State-IV). Such metallosupramolecular assemblies were found to reverse back to the fluorescence switching on state using a metal ion chelator DTPA (State-III), further signifying the role of metal ions towards assembly of 1. Formation of assembly and disassembly could be visualized by the diminished and increased yellow emission under green laser light. Further, the assembly-disassembly modulation of 1 has been extensively characterized using infrared (IR), mass spectrometry, microscopy and dynamic light scattering (DLS) techniques. Therefore, modulation of the molecular self-assembly of PDI derivative 1 in aqueous media (assembled state, State-II) by means of host-guest interactions provided by micellar structures of CTAB (disassembled state, State-III), metal ion (Fe3+ and Cu2+) interactions (assembled state, State-IV) and metal ion sequestration using DTPA (disassembled state, State-III) is viewed as a supramolecular reversible fluorescence switching off-on probe for cationic surfactant CTAB and Fe3+/Cu2+.
- Compositional epistasis: an epidemiologic perspective. [Journal Article]
- Methods Mol Biol 2015.:197-216.
Under Bateson's original conception, the term "epistasis" is used to describe the situation in which the effect of a genetic factor at one locus is masked by a variant at another locus. Epistasis in the sense of masking has been termed "compositional epistasis." In general, statistical tests for interaction are of limited use in detecting compositional epistasis. Using recently developed epidemiological methods, however, it has been shown that there are relations between empirical data patterns and compositional epistasis. These relations can sometimes be exploited to empirically test for certain forms of compositional epistasis, by using alternative nonstandard tests for interaction.Using the counterfactual framework, we show conditions that can be empirically tested to determine whether there are individuals whose phenotype response patterns manifest epistasis in the sense of masking. Only under some very strong assumptions would tests for standard statistical interactions correspond to compositional epistasis. Even without such strong assumptions, however, one can still test whether there are individuals of phenotype response type representing compositional epistasis. The empirical conditions are quite strong, but the conclusions which tests of these conditions allow may be of interest in a wide range of studies. This chapter highlights that epidemiologic perspectives can be used to shed light on underlying mechanisms at the genetic, molecular, and cellular levels.
- Gold crescent nanodisk array for nanoantenna-enhanced sensing in subwavelength areas. [JOURNAL ARTICLE]
- Appl Opt 2014 Nov 1; 53(31):7236-7240.
Benefitting from the antenna effect and localized surface plasmon resonance (LSPR), a metal nanoparticle with a designed morphology has the amazing ability to confine light energy into the required extremely small volume, whose refractive index largely affects the optical properties of the whole metal nanoparticle. In this work, the optical spectra and near-field distribution of a gold nanocrescent array were investigated both experimentally and theoretically. To find out the LSPR wavelength and the enhancement using different morphologies of sharp tips, the spectra of gold nanocrescent arrays with different waist widths (d) were first measured, which were then confirmed and analyzed using the finite difference time-domain method and the hybridization theory. At last, the LSPR of this array with 100 nm diameter dielectric nanodisks was studied for sensing in subwavelength areas. Our results showed that because of its giant nanoantenna-enhanced electromagnetic field at the two tips, this gold nanocrescent array could be a suitable local senor to sense the variation of a local medium in a subwavelength area.
- Sepsis-associated hyperlactatemia. [JOURNAL ARTICLE]
- Crit Care 2014 Sep 9; 18(5):503.
There is overwhelming evidence that sepsis and septic shock are associated with hyperlactatemia (sepsis-associated hyperlactatemia (SAHL)). SAHL is a strong independent predictor of mortality and its presence and progression are widely appreciated by clinicians to define a very high-risk population. Until recently, the dominant paradigm has been that SAHL is a marker of tissue hypoxia. Accordingly, SAHL has been interpreted to indicate the presence of an 'oxygen debt' or 'hypoperfusion', which leads to increased lactate generation via anaerobic glycolysis. In light of such interpretation of the meaning of SAHL, maneuvers to increase oxygen delivery have been proposed as its treatment. Moreover, lactate levels have been proposed as a method to evaluate the adequacy of resuscitation and the nature of the response to the initial treatment for sepsis. However, a large body of evidence has accumulated that strongly challenges such notions. Much evidence now supports the view that SAHL is not due only to tissue hypoxia or anaerobic glycolysis. Experimental and human studies all consistently support the view that SAHL is more logically explained by increased aerobic glycolysis secondary to activation of the stress response (adrenergic stimulation). More importantly, new evidence suggests that SAHL may actually serve to facilitate bioenergetic efficiency through an increase in lactate oxidation. In this sense, the characteristics of lactate production best fit the notion of an adaptive survival response that grows in intensity as disease severity increases. Clinicians need to be aware of these developments in our understanding of SAHL in order to approach patient management according to biological principles and to interpret lactate concentrations during sepsis resuscitation according to current best knowledge.
- Fighting for Wellness: Strategies of Mid-to-older Women Living with Cancer. [JOURNAL ARTICLE]
- J Cross Cult Gerontol 2014 Nov 14.
A significant portion of older adult cancer patients are using complementary and alternative medicine (CAM ) during and after treatment. I used four case studies to examine the strategies of older adult CAM-using cancer patients to maintain a sense of well-being as they transitioned to a post-treatment phase of life. Data were collected via qualitative interviews. Findings included strategies for financing CAM treatments, dealing with life disruption, and managing the complete nutritional overhaul recommended by their program. Participants worked to achieve new lifestyles and senses of wellness, finding ways to pay for expensive, out-of-pocket care while still meeting family obligations. These findings shed light on assumptions about older adult health-seeking behaviors, culturally embedded life course expectations, and raised questions about how the pursuit of health activities involving boundary crossings are received.
- Light and gravity signals synergize in modulating plant development. [Journal Article, Review]
- Front Plant Sci 2014.:563.
Tropisms are growth-mediated plant movements that help plants to respond to changes in environmental stimuli. The availability of water and light, as well as the presence of a constant gravity vector, are all environmental stimuli that plants sense and respond to via directed growth movements (tropisms). The plant response to gravity (gravitropism) and the response to unidirectional light (phototropism) have long been shown to be interconnected growth phenomena. Here, we discuss the similarities in these two processes, as well as the known molecular mechanisms behind the tropistic responses. We also highlight research done in a microgravity environment in order to decouple two tropisms through experiments carried out in the absence of a significant unilateral gravity vector. In addition, alteration of gravity, especially the microgravity environment, and light irradiation produce important effects on meristematic cells, the undifferentiated, highly proliferating, totipotent cells which sustain plant development. Microgravity produces the disruption of meristematic competence, i.e., the decoupling of cell proliferation and cell growth, affecting the regulation of the cell cycle and ribosome biogenesis. Light irradiation, especially red light, mediated by phytochromes, has an activating effect on these processes. Phytohormones, particularly auxin, also are key mediators in these alterations. Upcoming experiments on the International Space Station will clarify some of the mechanisms and molecular players of the plant responses to these environmental signals involved in tropisms and the cell cycle.
- Electron microscopy in rapid viral diagnosis: an update. [Journal Article]
- New Microbiol 2014 Oct; 37(4):403-22.
Diagnostic electron microscopy (DEM) has conceptual predecessors â€" the application of the sense of vision and of light microscopy in medicine. The evolvement of DEM and the role of its two branches - histopathology and rapid negative-contrast DEM - are described in this review, with a focus on the latter. By its resolving power of 2 nm in praxi, DEM is able to visualize all kinds of pathogens, bacteria, parasites, even the smallest viruses. In contrast to other laboratory diagnostic methods, DEM excels by speed and "open view". All structures on the support grid can be assigned directly by "pattern recognition" of their fine structure to a specific family of agents. The morpholo- gy-based "catch-all" diagnosis can be decisive as a differential diagnosis and will help as a preliminary diagnosis to select and apply proper diagnostic tools for typing of the observed agent. Based on two case reports, the advantages and possible pitfalls of DEM are exemplified and hints are given to make DEM reliable and effective. Finally the role of DEM in medicine and the wider fields of life sciences are described together with the organizational condi- tions to guarantee its future in laboratory diagnostics.