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light sense [keywords]
- Prolonged Mechanical Stretch Initiates Intracellular Calcium Oscillations in Human Mesenchymal Stem Cells. [JOURNAL ARTICLE]
- PLoS One 2014; 9(10):e109378.
Mesenchymal stem cells (MSCs) are a promising candidate for cell-based therapy in regenerative medicine. These stem cells can interact with their mechanical microenvironment to control their functions. External mechanical cues can be perceived and transmitted into intracellular calcium dynamics to regulate various cellular processes. Recent studies indicate that human MSCs (hMSCs) exhibit a heterogeneous nature with a subset of hMSCs lacking spontaneous calcium oscillations. In this study, we studied whether and how external mechanical tension can be applied to trigger and restore the intracellular calcium oscillation in these hMSCs lacking spontaneous activities. Utilizing the fluorescence resonance energy transfer (FRET) based calcium biosensor, we found that this subpopulation of hMSCs can respond to a prolonged mechanical stretch (PMS). Further results revealed that the triggering of calcium oscillations in these cells is dependent on the calcium influx across the plasma membrane, as well as on both cytoskeletal supports, myosin light chain kinase (MLCK)-driven actomyosin contractility, and phospholipase C (PLC) activity. Thus, our report confirmed that mechanical tension can govern the intracellular calcium oscillation in hMSCs, possibly via the control of the calcium permeability of channels at the plasma membrane. Our results also provide novel mechanistic insights into how hMSCs sense mechanical environment to regulate cellular functions.
- Clinical and nerve conduction study correlation in patients of diabetic neuropathy. [Journal Article]
- J Assoc Physicians India 2014 Jan; 62(1):24-7.
1) To study types of neuropathy in Type 2 diabetes. 2) To correlate clinical features of peripheral neuropathy with nerve conduction study in Type 2 diabetes.A total of 50 diabetics, whose onset of diabetes after the age of 30 years were studied from Dr. D. Y. Patil hospital and research centre. Type 2 Diabetes mellitus with symptom suggestive of peripheral neuropathy were studied and included. Chronic alcoholic, peripheral neuropathy due to any other known cause were excluded. METHOD OF COLLECTION OF DATA: History of symptoms like paraesthesia like tingling sensation, burning feet, hyperaesthesia, foot ulcer, history of weakness and gait abnormality was noted. Complete central nervous system examination was performed to look for signs such as diminished ankle jerk, diminished power. Sensory examination for loss of light touch, superficial pain, temperature sense, vibration and joint position was done. Nerve conduction studies were performed using Clarity Octopus NCV/EMG machine. Written and informed consent from patient were taken.1) 46 patients i.e. 92% presented with complaints of tingling sensation and 32 patients i.e. 64% had burning feet. 2) 29 patients i.e. 58% have diminished ankle jerk, 29 patients i.e. 58% have diminished or loss of vibration sense, in 21 patients i.e. 42% patients have diminished light touch and 20 patients i.e. 40% patients have loss of joint position senses. 3) NCV performed on 50 patients of diabetic neuropathy out of which all patients i.e. 100% had involvement of lower limb and only 24 patients i.e. 48% had involvement of upper limb also. 4) Involvement of tibial and sural nerve is more common i.e. 86% and 82% respectively. 5) 42 patients i.e. 84% found to have distal symmetrical polyneuropathy, 2 patients i.e. 4% had isolated tibial nerve involvement, 4 patients i.e. 8% had pure sensory sural nerve involvement, and only 1 patient each of isolated medial and plantar nerve involvement.Distal symmetrical polyneuropathy is most common form of diabetic neuropathy. Involvement of tibial and sural nerve is more common in diabetic neuropathy.
- Fungal photobiology: visible light as a signal for stress, space and time. [JOURNAL ARTICLE]
- Curr Genet 2014 Oct 17.
Visible light is an important source of energy and information for much of life on this planet. Though fungi are neither photosynthetic nor capable of observing adjacent objects, it is estimated that the majority of fungal species display some form of light response, ranging from developmental decision-making to metabolic reprogramming to pathogenesis. As such, advances in our understanding of fungal photobiology will likely reach the broad fields impacted by these organisms, including agriculture, industry and medicine. In this review, we will first describe the mechanisms by which fungi sense light and then discuss the selective advantages likely imparted by their ability to do so.
- Spectral method for fast measurement of twisted nematic liquid crystal cell parameters. [JOURNAL ARTICLE]
- Appl Opt 2014 Aug 10; 53(23):5230-5237.
We present an experimental approach for the fast measurement of twisted nematic (TN) liquid crystal (LC) cells' parameters. It is based on the spectral measurements of the light transmitted by the system polarizer-reference wave plate-LC cell-analyzer. The cell parameters are obtained by fitting the theoretical model to the experimental data. This method allows determining the rubbing angle, the twist angle and its sense, and the spectral dispersion of the LC cell retardation, simultaneously, with few measurements and without the need of applying voltage or any specific analytical conditions. The method is validated by characterizing two different TN cells with retardations of about 0.91 and 1.85 μm. The birefringence relative error is less than 1.3%.
- Assessment of light touch sensation in the hands of systemic sclerosis patients. [Journal Article]
- Clinics (Sao Paulo) 2014 Sep; 69(9):585-8.
Systemic sclerosis is a relatively rare connective tissue disorder characterized by severe and progressive fibrosis of the skin. Due to the current lack of available information on this subject, the aim of the present study was to assess light touch sensations in the hands of patients with systemic sclerosis.We completed a cross-sectional comparative study. Light touch sensations were evaluated in 30 individuals, including 15 patients with systemic sclerosis who exhibited changes in the dermis of their hands without loss of the distal phalanx and 15 subjects who did not exhibit changes in the upper limbs (control group). The groups were age- and sex-matched. Tactile sensory evaluations were performed using the Semmes-Weinstein monofilament test and the two-point discrimination test.Statistically significant differences were found between groups in the monofilament test. The study group had lower scores across all points of the hand when compared with the control group. Differences were also found when dominant and non-dominant hands were compared (p<0.05). Statistically significant differences were found between groups for a subset of the assessed points in the two-point discrimination test.The results of a monofilament test showed that tactile sensation, specifically light touch and deep pressure sensations, is altered in the hands of systemic sclerosis patients.
- A neural interface provides long-term stable natural touch perception. [Journal Article]
- Sci Transl Med 2014 Oct 8; 6(257):257ra138.
Touch perception on the fingers and hand is essential for fine motor control, contributes to our sense of self, allows for effective communication, and aids in our fundamental perception of the world. Despite increasingly sophisticated mechatronics, prosthetic devices still do not directly convey sensation back to their wearers. We show that implanted peripheral nerve interfaces in two human subjects with upper limb amputation provided stable, natural touch sensation in their hands for more than 1 year. Electrical stimulation using implanted peripheral nerve cuff electrodes that did not penetrate the nerve produced touch perceptions at many locations on the phantom hand with repeatable, stable responses in the two subjects for 16 and 24 months. Patterned stimulation intensity produced a sensation that the subjects described as natural and without "tingling," or paresthesia. Different patterns produced different types of sensory perception at the same location on the phantom hand. The two subjects reported tactile perceptions they described as natural tapping, constant pressure, light moving touch, and vibration. Changing average stimulation intensity controlled the size of the percept area; changing stimulation frequency controlled sensation strength. Artificial touch sensation improved the subjects' ability to control grasping strength of the prosthesis and enabled them to better manipulate delicate objects. Thus, electrical stimulation through peripheral nerve electrodes produced long-term sensory restoration after limb loss.
- Title: Distinct palisade tissue development processes promoted by leaf-autonomous signaling and long-distance signaling in Arabidopsis thaliana. [JOURNAL ARTICLE]
- Plant Cell Environ 2014 Oct 8.
Plants develop palisade tissue consisting of cylindrical mesophyll cells located at the adaxial-side of leaves in response to high light. To understand high light signaling in palisade tissue development, we investigated leaf-autonomous and long-distance signal responses of palisade tissue development using Arabidopsis thaliana. Illumination of a developing leaf with high light induced cell height elongation, whereas illumination of mature leaves with high light increased cell density and suppressed cell width expansion in palisade tissue of new leaves. Examination using phototropin1 phototropin2 showed that blue light signaling mediated by phototropins was involved in cell height elongation of the leaf-autonomous response rather than the cell density increase induced by long-distance signaling. Hydrogen peroxide treatment induced cylindrical palisade tissue cell formation in both a leaf-autonomous and long-distance manner, suggesting involvement of oxidative signals. Although constitutive expression of transcription factors involved in systemic acquired acclimation to excess light, ZAT10 and ZAT12, induced cylindrical palisade tissue cell formation, knockout of these genes did not affect cylindrical palisade tissue cell formation. We conclude that two distinct signaling pathways-leaf-autonomous signaling mostly dependent on blue light signaling and long-distance signaling from mature leaves that sense high light and oxidative stress-control palisade tissue development in A. thaliana.
- Developmental Neuroscience: How Twitches Make Sense. [JOURNAL ARTICLE]
- Curr Biol 2014 Oct 6; 24(19):R971-R972.
Animals refine the mechanics of their own bodies through sensorimotor feedback produced by physical interactions with the environment. A new study sheds light on how developing mammals may use sensations produced by spontaneous movements made during sleep to construct their sensorimotor maps.
- Self-referential memory in autism spectrum disorder and typical development: Exploring the ownership effect. [JOURNAL ARTICLE]
- Conscious Cogn 2014 Oct 3.:133-141.
Owned objects occupy a privileged cognitive processing status and are viewed almost as extensions of the self. It has been demonstrated that items over which a sense of ownership is felt will be better remembered than other items (an example of the "self-reference effect"). As autism spectrum disorder (ASD) is characterised by an a typical self-concept, people with ASD may not demonstrate this "ownership effect". Two experiments were conducted which replicate and extend Cunningham, Turk, MacDonald, and Macrae (2008). In Experiment 1, neurotypical adults completed a card sorting task and cards belonging to the 'self' were better remembered than cards belonging to another person. In Experiment 2, adults with ASD recalled self- and other owned items equally well. These results shed light both on the relation between sense of self and the ownership effect, and the nature of the self-concept in ASD.
- Peripheral hypertrophic subepithelial corneal degeneration presenting with bilateral nasal and temporal corneal changes. [JOURNAL ARTICLE]
- Eye (Lond) 2014 Oct 3.
PurposeTo characterise the history, clinical and histopathological features of patients with bilateral nasal and temporal peripheral hypertrophic subepithelial corneal degeneration in a German population.MethodsA detailed ophthalmological and dermatological history and clinical findings were recorded of nine patients with bilateral simultaneous nasal and temporal peripheral corneal degeneration from two centers in Germany. Excised tissues were studied by histopathology, immunohistochemistry, and transmission electron microscopy.ResultsForeign body sensation and need of artificial tear substitutes were the only symptoms reported regularly. Schirmer's and Jones-test were normal in all, but fluorescein break-up time of >10 s was found in five eyes of four patients. Best corrected visual acuity was reduced only under glare conditions. Corneal topography revealed irregular astigmatism in 13 of 14 eyes. Follow-up median time was 35 months. Most cases were stable within the follow-up period. Light and electron microscopy revealed the findings of superficial vascularised corneal hypertrophic scars, oxytatlan fibers, and discontinued Bowmans layer.ConclusionIn this series of German patients with peripheral hypertrophic subepithelial corneal degeneration, the changes were predominantly located in the palpebral aperture and often present in both eyes. No associated surface disease could be established in this study. Light and transmission electron microscopy showed histological features that are similar to Salzmann's corneal changes without any inflammation. We hypothesise that light exposure and a localised limbal insufficiency could be involved in the pathogenesis.Eye advance online publication, 3 October 2014; doi:10.1038/eye.2014.236.