In the present paper, we study infinitesimal symmetries, natural infinitesimal symmetries, Newtonoid sections, infinitesimal Noether symmetries, and conservation laws for Hamiltonian systems within ...the general framework of Lie algebroids. Using dynamical covariant derivatives and Jacobi endomorphisms, we find invariant equations of some type of symmetries and prove that the canonical nonlinear connection induced by a regular Hamiltonian can be determined by these symmetries. Finally, we present examples from the optimal control theory that prove that the framework of Lie algebroids is more useful than the cotangent bundle in order to study the symmetries for the dynamics induced by a Hamiltonian function.
A highly heterogeneous population of stem and progenitor cells has been described by light immunohistochemistry in the mammalian adult heart, but the ultrastructural identity of cardiac stem cells ...remains unknown. Using electron microscopy, we demonstrate the presence of cells with stem features in the adult mouse heart. These putative cardiac stem cells are small (6–10 μm), round cells, with an irregular shaped nucleus, large nucleolus, few endoplasmic reticulum cisternae and mitochondria, but numerous ribosomes. Stem cells located in the epicardial stem cell niche undergo mitosis and apoptosis. Cells with intermediate features between stem cells and cardiomyocyte progenitors have also been seen. Moreover, electron microscopy showed that cardiomyocyte progenitors were added to the peripheral working cardiomyocytes. Telocytes make a supportive interstitial network for stem cells and progenitors in the stem cell niche. This study enhances the hypothesis of a unique type of cardiac stem cell and progenitors in different stages of differentiation. In our opinion, stem cells, cardiomyocyte progenitors and telocytes sustain a continuous cardiac renewal process in the adult mammalian heart.
Ramon y Cajal discovered a particular cell type in the gut, which he named ‘interstitial neurons’ more that 100 years ago. In the early 1970s, electron microscopy/electron microscope (EM) studies ...showed that indeed a special interstitial cell type corresponding to the cells discovered by Cajal is localized in the gut muscle coat, but it became obvious that they were not neurons. Consequently, they were renamed ‘interstitial cells of Cajal’ (ICC) and considered to be pace‐makers for gut motility. For the past 10 years many groups were interested in whether or not ICC are present outside the gastrointestinal tract, and indeed, peculiar interstitial cells were found in: upper and lower urinary tracts, blood vessels, pancreas, male and female reproductive tracts, mammary gland, placenta, and, recently, in the heart as well as in the gut. Such cells, now mostly known as interstitial Cajal‐like cells (ICLC), were given different and confusing names. Moreover, ICLC are only apparently similar to canonical ICC. In fact, EM and cell cultures revealed very particular features of ICLC, which unequivocally distinguishes them from ICC and all other interstitial cells: the presence of 2–5 cell body prolongations that are very thin (less than 0.2 μm, under resolving power of light microscopy), extremely long (tens to hundreds of μm), with a moniliform aspect (many dilations along), as well as caveolae. Given the unique dimensions of these prolongations (very long and very thin) and to avoid further confusion with other interstitial cell types (e.g. fibroblast, fibrocyte, fibroblast‐like cells, mesenchymal cells), we are proposing the term TELOCYTES for them, and TELOPODES for their prolongations, by using the Greek affix ‘telos’.
Telocytes in meninges and choroid plexus Popescu, B.O.; Gherghiceanu, M.; Kostin, S. ...
Neuroscience letters,
05/2012, Letnik:
516, Številka:
2
Journal Article
Recenzirano
► Telocytes are a recently identified type of interstitial cells. ► We identified telocytes in rat meninges and choroid plexus. ► Telocytes form an interstitial network in the interstitium. ► ...Telocytes have direct cell–cell contacts with stem cells.
Telocytes (TCs) are a recently identified type of interstitial cells present in a wide variety of organs in humans and mammals (www.telocytes.com). They are characterized by a small cell body, but extremely long cell processes – telopodes (Tp), and a specific phenotype. TCs establish close contacts with blood capillaries, nerve fibers and stem cells. We report here identification of TCs by electron microscopy and immunofluorescence in rat meninges and choroid plexus/subventricular zone, in the vicinity of putative stem cells. The presence of TCs in brain areas involved in adult neurogenesis might indicate that they have a role in modulation of neural stem cell fate.
Telocytes (TCs), a particular interstitial cell type, have been recently described in a wide variety of mammalian organs (www.telocytes.com). The TCs are identified morphologically by a small cell ...body and extremely long (tens to hundreds of μm), thin prolongations (less than 100 nm in diameter, below the resolving power of light microscopy) called telopodes. Here, we demonstrated with electron microscopy and immunofluorescence that TCs were present in human dermis. In particular, TCs were found in the reticular dermis, around blood vessels, in the perifollicular sheath, outside the glassy membrane and surrounding sebaceous glands, arrector pili muscles and both the secretory and excretory portions of eccrine sweat glands. Immunofluorescence screening and laser scanning confocal microscopy showed two subpopulations of dermal TCs; one expressed c‐kit/CD117 and the other was positive for CD34. Both subpopulations were also positive for vimentin. The TCs were connected to each other by homocellular junctions, and they formed an interstitial 3D network. We also found TCs adjoined to stem cells in the bulge region of hair follicles. Moreover, TCs established atypical heterocellular junctions with stem cells (clusters of undifferentiated cells). Given the frequency of allergic skin pathologies, we would like to emphasize the finding that close, planar junctions were frequently observed between TCs and mast cells. In conclusion, based on TC distribution and intercellular connections, our results suggested that TCs might be involved in skin homeostasis, skin remodelling, skin regeneration and skin repair.
In this study, a novel molecularly imprinted polymer (MIP) sensor for the electrochemical detection of sodium lauryl sulfate (SLS) is reported. The MIP based screen-printed gold electrode (Au-SPE) ...was prepared by an electrochemical polymerization of 2-aminothiophenol (2-ATP) in the presence of SLS as target molecule. For control, a non-imprinted polymer (NIP) sensor was also constructed identically by omitting the SLS template. Moreover, the selectivity of the proposed MIP sensor was investigated by using analogues such as Ethylenediaminetetraacetic acid (EDTA), Tween 80 and Urea, revealing satisfactory selectivity toward SLS. The electrochemical characterization of the elaborated sensor was performed using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques. The morphology of the MIP sensor was studied by means of Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy (FTIR) methods. Some experimental parameters such as number of cycle for the electropolymerization, incubation time of 2-ATP, elution and SLS incubation time, were optimized to improve the sensor performances. Under optimal conditions, the electrochemical sensor exhibits a logarithmic working range from 0.1 to 1000 pg/mL, and a detection limit of 0.18 pg/mL. Additionally, compared with reported works, the sensor possesses remarkable properties, such as a higher sensitivity and selectivity, a good reproducibility, a wider logarithmic range, a lower detection limit and a long-term stability. As real application, the developed MIP sensor was well employed to determine SLS contents in environmental waters and cosmetic products samples. A UV–vis spectrophotometer was used as reference method. A partial least squares (PLS) technique was well employed to study the correlation between the spectrophotometer and the MIP sensor technology with a satisfactory regression coefficient (R = 0.99). The obtained results during the sensor development and applications suggested an interesting and valuable tool for environmental analysis.
Display omitted
•An electrochemical molecularly imprinted sensor for SLS detection is proposed.•The sensor shows high sensitivity and good selectivity.•The imprinted sensor exhibits good reproducibility and long-term storage.•A lower LOD of 0.18 pg/mL is achieved in this study compared to reported works.•Obtainment of satisfactory sensor results correlated with the spectrophotometric method’s.
► We used different ratios of alginate and k-carrageenan to obtain composite films. ► The composite films were cross-linked in two stages with CaCl2. ► The structures of the composite films were ...analysed by FTIR, XRD, DTG, TG and SEM. ► Cross-linked composite films show mechanical and swelling properties of hydrogels. ► The 1/3 alginate/k-carrageenan films are suitable for drug delivery applications.
The purpose of this work was to prepare an alginate/k-carrageenan composite film cross-linked with CaCl2 that could be used in biomedical applications. The influence of the alginate/carrageenan ratio on the composite films properties was studied in order to establish the optimal composition of the films. Several characterization methods such as: FTIR, XRD, TG/DTG, SEM were used, and the mechanical properties and the swelling behaviour of the obtained composite films were studied.
Telocytes (TCs) are a particular type of interstitial (stromal) cells defined by very long, moniliform telopodes. Their tissue location, between blood vessels and other cells such as cardiomyocytes ...(CMC) and neurons, suggests a role in intercellular signalling. In order to define a microRNA (miR) signature in cardiac TCs, we have found that miR‐193 is differentially expressed between TCs and other interstitial cells. Because miR‐193 regulates c‐kit, our data support the previous finding that TCs express c‐kit in certain circumstances. In addition, the miRs which are specific to CMC and other muscle cells (e.g. miR‐133a, miR‐208a) are absent in TCs. Overall the data reinforce the view that TCs are a particular type of interstitial (mesenchymal) cells.
We used rat experimental myocardial infarction to study the ultrastructural recovery, especially neo‐angiogenesis in the infarction border zone. We were interested in the possible role(s) of ...telocytes (TCs), a novel type of interstitial cell very recently discovered in myocardim (see http://www.telocytes.com). Electron microscopy, immunocytochemistry and analysis of several proangiogenic microRNAs provided evidence for TC involvement in neo‐angiogenesis after myocardial infarction. Electron microscopy showed the close spatial association of TCs with neoangiogenetic elements. Higher resolution images provided the following information: (a) the intercellular space between the abluminal face of endothelium and its surrounding TCs is frequently less than 50 nm; (b) TCs establish multiple direct nanocontacts with endothelial cells, where the extracellular space seems obliterated; such nanocontacts have a length of 0.4–1.5 μm; (c) the absence of basal membrane on the abluminal face of endothelial cell. Besides the physical contacts (either nanoscopic or microscopic) TCs presumably contribute to neo‐angiognesis via paracrine secretion (as shown by immunocytochemistry for VEGF or NOS2). Last but not least, TCs contain measurable quantities of angiogenic microRNAs (e.g. let‐7e, 10a, 21, 27b, 100, 126‐3p, 130a, 143, 155, 503). Taken together, the direct (physical) contact of TCs with endothelial tubes, as well as the indirect (chemical) positive influence within the ‘angiogenic zones’, suggests an important participation of TCs in neo‐angiogenesis during the late stage of myocardial infarction.
The term TELOCYTES was very recently introduced, for replacing the name Interstitial Cajal‐Like Cells (ICLC). In fact, telocytes are not really Cajal‐like cells, they being different from all other ...interstitial cells by the presence of telopodes, which are cell‐body prolongations, very thin (under the resolving power of light microscopy), extremely long (tens up to hundreds of micrometers), with a moniliform aspect (many dilations along), and having caveolae. The presence of telocytes in epicardium and myocardium was previously documented. We present here electron microscope images showing the existence of telocytes, with telopodes, at the level of mouse endocardium. Telocytes are located in the subendothelial layer of endocardium, and their telopodes are interposed in between the endocardial endothelium and the cardiomyocytes bundles. Some telopodes penetrate from the endocardium among the cardiomyocytes and surround them, eventually. Telopodes frequently establish close spatial relationships with myocardial blood capillaries and nerve endings. Because we may consider endocardium as a ‘blood–heart barrier’, or more exactly as a ‘blood–myocardium barrier’, telocytes might have an important role in such a barrier being the dominant cell population in subendothelial layer of endocardium.
PDF
