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Prospects of Nanotechnology in Brain Targeting Drug Delivery
Published in Bhaskar Mazumder, Subhabrata Ray, Paulami Pal, Yashwant Pathak, Nanotechnology, 2019
Srijita Chakrabarti, Probin Kr Roy, Pronobesh Chattopadhyay, Bhaskar Mazumder
The blood capillaries of the CNS are structurally different from other tissue capillaries and there is a permeability barrier between the blood within the brain capillaries and the extracellular tissue. Vertebrate brain capillaries lack the small pores which allow rapid movement of solutes from circulation into other organs. This permeability barrier, comprising the brain capillary endothelium, is known as the BBB. The BBB prevents most of the CNS drugs from entering into the brain, except for highly lipid-soluble molecules under a threshold of 400–600 Da (Yang et al., 1999). The brain parenchyma is made up of neurons and neuroglia cells. Neuroglia cells provide structural support to the neighbouring neurons (Araque et al., 1999; Compston et al., 1997). They were classified as neuroglia or “nerve glue” owing to their spindle-like form and their “soft, medullary, fragile nature”. However, the neuroglia cells are now known not only for their structural roles, but also for having multiple functions in regulating an optimal interstitial environment (Lee et al., 2001). There are two primary types of neuroglia cells that comprise the brain parenchyma: the macroglia and microglia.
Liver
Published in Alan G. Heath, Water Pollution and Fish Physiology, 2018
Parenchymal cells (hepatocytes) are the dominant type of cell present in liver. These range in shape from oval to irregular polygons; their ultrastructure has been described by Leland (1983). As would be expected from the functions of the liver, these cells are well endowed with secretory and biosynthetic structures, such as Golgi bodies and rough endoplasmic reticulum. Juvenile rainbow trout appear to have a near absence of these cellular structures, which develop as the fish matures (Chapman, 1981; Leland, 1983). This implies that biotransformation and excretion of xenobiotics may be severely limited in younger fish. However, some induction of the biotransformation enzymes is possible by xenobiotic exposure even in the embryos (Binder and Stegeman, 1983).
X-ray Phase-Contrast Mammography
Published in Paolo Russo, Handbook of X-ray Imaging, 2017
Pekka Suortti, Jani Keyriläinen, William Thomlinson
ABI was the first application in the field of PCM. Following the pioneering work of Förster et al. (1980), Davis et al. (1995) Ingal and Beliaevskaya (1995) and Ingal et al. (1998) used a basic two crystal ABI setup on a conventional laboratory X-ray source to analyze excised breast tissue containing various malignant and benign tumors, as well as calcifications. They showed the enhancement of mammographic radiology features compared to conventional absorption images as they varied the position of the analyzer crystal on the RC. Although they did not quantify the enhancement due to phase-contrast mechanisms, they clearly showed that phase-contrast imaging could be useful in the visualization of breast anomalies. In particular, the refraction contrast combined with the absorption signal proved to be useful. Perhaps most importantly, these experiments demonstrated that the coherence of the source was not critical to obtaining phase information. The low flux available from their X-ray generator and the film systems used for data collections had the effect of very long imaging times and high radiation doses. With the phase information and the use of the film detectors with clinical spatial resolution, the images did show the changes in parenchyma structure. Parenchyma consists of the functional elements of an organ, as distinguished from supporting or connective tissue. These changes were due to malignancy and micro-calcifications down to 50 microns in size, with the results verified by histological examination. Overall, the ABI images were superior to the standard absorption images to which they were compared. With improvements in the X-ray source and detector efficiency, they concluded that a mammography system with exposures of less than 1 second would be feasible.
Experimental protocol to evaluate lung parenchyma properties under inflation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
T. Pallière, A. Lanel, A. Bel-Brunon, K. Bruyère-Garnier, N. Biboulet, T. Lubrecht
Lung parenchyma is a multiscale foam-like tissue with several intricate phenomena. During inspiration, the diaphragm creates a depression on the lung cavity forcing air to enter; alveoli dilatation is favored by the presence of surfactant, a biofilm which decreases the surface tension on the inner surface of the alveoli. Lung parenchyma is composed of vasculature, air ducts, alveolar walls, surfactant; a loss of equilibrium between these components can lead to pathologies, such as fibrosis or emphysema, causing a mechanical vicious circle (Hinz and Suki 2016). Understanding how lung parenchyma behaves mechanically with its different components is still a challenge. Experimental characterization has been performed at the organ scale (Richardson et al. 2017) or on tissue strips (Bel-Brunon et al. 2014) but the former includes structural effects while the latter does not allow for realistic loading (inflation), leading to a poor identification of the constitutive law. The aim of the presented protocol is to acquire experimental data related to lung parenchyma inflation to build and identify a component-based constitutive law for this tissue, focusing on small scales (from alveoli to sub-segment). So to reach a sufficient imaging resolution, the protocol is designed for sub-segment lobules.