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Outdoor Air Pollution
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Throughout the body's tissue, bulk flow of the fluid between cells, into the blood or lymph, plays an important role in the removal of potentially toxic metabolic by-products. Lymphatic vessels are the principal means by which tissues eliminate excess fluid and proteins from the body, although the density of lymph vessels generally correlates with tissue metabolic rate.5 Thus, it is puzzling because the high metabolic activity of neurons predicts the need for rapid elimination of their metabolic by-products. It was long thought that the movement of the cerebrospinal fluid (CSF), which is produced in the choroid plexus of the brain and flows through its ventricles and basal cisterns, constitutes a “sink” for waste products to diffuse from the brain, for eventual clearance to the general circulation. However, the large tissue distances in most of the brain prevent diffusion and bulk flow from making this process efficient. Albumin, for instance, would require more than 100 hours to diffuse through 1 cm of brain tissue.6
Nanoemulsion for Brain Targeting
Published in Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani, Nanocarriers for Brain Targeting, 2019
Khushwinder Kaur, Shivani Uppal
Pia Mater means “tender mother.” It is a skinny sheer membrane, covering the exterior of the brain and central nervous system (CNS). Compared with the other layers, this tissue holds closely to the brain, operating down into the sulci and fissures of the cortex. It forms choroid plexus by fusing with the ependyma, to produce CSF.
Advances in CSF shunt devices and their assessment for the treatment of hydrocephalus
Published in Expert Review of Medical Devices, 2021
Kamran Aghayev, Sheikh MA Iqbal, Waseem Asghar, Bunyad Shahmurzada, Frank D. Vrionis
CSF shunt devices have high failure rates with 30–40% of them within the first year and almost 50% during the first two years [20]. This high failure rate is due to the inherent complications associated with CSF shunt devices and include: infection, shunt malfunction and catheter obstruction [21,22]. It’s been demonstrated that the main cause of shunt malfunction is the obstruction of the ventricular catheter (VC) [23–25]. This obstruction is caused by ingrowth of the choroid plexus, ependyma, brain parenchyma or inflammatory tissue into catheter holes as a reaction to foreign body. This problem is also important from management standpoint since obstructed catheter needs surgical retrieval. However, blind pulling may result in choroid plexus laceration and cause profound bleeding unnoticed by the surgeon. Open or endoscopic ventricular catheter retrieval are alternatives to blind pulling yet they increase operative time and predispose to additional complications. In some cases, the surgeon may opt out retrieval and insert a new catheter from other point. Decreasing the tissue reaction with catheter blockage is one of the most important shunt development directions.
Numerical analysis of enhanced nano-drug delivery to the olfactory bulb
Published in Aerosol Science and Technology, 2021
Shantanu Vachhani, Clement Kleinstreuer
The Blood Brain Barrier (BBB) located above the olfactory bulb (Figure 1), a highly selective semipermeable membrane, protects the fragile nature of the brain and separates the olfactory region of the nasal cavity from the brain. The presence of tight junctions between the adjacent endothelial cells (Figure 2) allow only very small compounds to pass through (Azad et al. 2015; Burgess and Hynynen 2013). Furthermore, the cerebral endothelial cells show a considerably less pinocytic activity than the systemic endothelium (Lesniak and Brem 2004). Pinocytic activity results in the transportation of substances across an epithelium by material-uptake on one face of a coated vesicle that can then be transported from the opposite face. Clearly, the reduction in the pinocytic activity further limits the drug transportation across the BBB. The blood cerebrospinal fluid barrier (BCSFB) forms the second layer that restricts the movement of drugs. This layer is located at the choroid plexus and separates the blood and the cerebrospinal fluid. However, this layer is slightly more permeable than the BBB. The BBB surface area (120 sq ft) is roughly 5000 times the area of the BCSFB (Pajouhesh and Lenz 2005). Hence, BBB layer is the dominant obstacle for the delivery of drugs to the brain. These membranes are there to inhibit the passage of pathogens, antibodies, toxins etc. to the brain. In doing so they also restrict the transport of therapeutic drugs in to the brain. In summary, drug delivery to the brain is difficult to achieve at high enough efficiencies to counteract the toxins that are the root to the various CNS disorders (Agrawal et al. 2018).
Review on the current treatment status of vein of Galen malformations and future directions in research and treatment
Published in Expert Review of Medical Devices, 2021
Panagiotis Primikiris, Georgios Hadjigeorgiou, Maria Tsamopoulou, Alessandra Biondi, Christina Iosif
Vein of Galen aneurysmal malformations (VOGMs) are rare, congenital, high-flow, intracranial vascular disorders accounting for about 1% of all pediatric congenital anomalies [1,2]. VOGM is located in the subarachnoid space in the choroid fissure and embryologically related to the development of the choroid plexus. It is defined as arteriovenous shunts draining to the embryonic precursor of the vein of Galen, called median prosencephalic vein (MProsV) of Markowski and are further sub-classified into choroidal and the mural types [3]. VOGMs result from abnormal morphogenesis of the choroidal vasculature, between the eighth and eleventh weeks of gestation [4].