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Stomach Microcirculation
Published in John H. Barker, Gary L. Anderson, Michael D. Menger, Clinically Applied Microcirculation Research, 2019
Ivarsson et al.41 measured gastric blood flow by recording the elimination of intraarterially injected Krypton-85. This method allows the measurement of total gastric blood flow and its distribution in animals and human subjects. Elimination of krypton is monitored with two external detectors: a scintillation detector recording the disappearance of γ-activity from the entire gastric wall and a G-M tube recording the disappearance of β-activity from the muscle layer only. Total and muscle layer blood flow can be calculated from the washout curves. It is possible to calculate mucosa-submucosa blood flow by knowing total and muscle blood flow and the relative weights of the mucosa, submucosa, and muscle layers. Experience with this method is very limited and its importance and accuracy have not been determined yet.
Haemodynamics: flow, pressure and resistance
Published in Neil Herring, David J. Paterson, Levick's Introduction to Cardiovascular Physiology, 2018
Neil Herring, David J. Paterson
Microvascular blood flow in a small region of human tissue can be estimated from the rate of washout of a locally injected radioisotope. A rapidly diffusing, radioactive solute is injected as a local, interstitial depot (Figure 8.6). The solute is gradually cleared from the depot by diffusion into the neighbouring capillaries, which carry the solute away. Removal is recorded by a gamma-counter over the depot. If the solute diffusion rate is fast enough, clearance is limited solely by the capillary blood flow and is directly proportional to the blood flow (‘Flow-limited exchange’, Section 10.10). A small, lipid-soluble radioisotope, such as xenon-133 or krypton-85, is used to achieve the necessary high diffusion rate. In 1949, Kety pointed out that, given flow-limited exchange, the solute concentration declines exponentially with time, so a plot of the natural logarithm of concentration C against time t is linear (Figure 8.6). Its slope, k, is called the removal rate constant:
The small airway epithelium as a target for the adverse pulmonary effects of silver nanoparticle inhalation
Published in Nanotoxicology, 2018
Chang Guo, Alison Buckley, Tim Marczylo, Joanna Seiffert, Isabella Römer, James Warren, Alan Hodgson, Kian Fan Chung, Timothy W. Gant, Rachel Smith, Martin O. Leonard
AgNP aerosols were produced using a spark generator (DNP 4000; Palas, Karlsruhe, Germany) by the homogeneous nucleation of vapor produced between two electrodes (5 × 1 mm silver wire; Premion™ 99.999% purity, Alfa Aesar™; Heysham, UK) in an inert argon atmosphere. The rate of primary particle production and final size was dependent on the sparking frequency (90–300 Hz). The particles were passed through a krypton-85 charge neutralizer (Model 3077A, TSI Inc., Shoreview, MN) prior to dilution and experimental exposure. A condensation particle counter (CPC model 3775, TSI Inc.) continuously monitored the aerosol particle number concentration during exposures and aerosol mass concentrations were determined gravimetrically using Pallflex® emfab™ filters (Pall Life Sciences, Ann Arbor, MI) with the aerosol drawn at 2 L min−1, the results are presented in Table 1. The average number-weighted aerosol particle size distribution was determined using a scanning mobility particle sizer (SMPS; model 3936N76, TSI Inc.) and for in vitro exposures results are displayed in Supplementary Figure 1(A). The shape of the aerosol particles was determined with high-resolution transmission electron microscopy (TEM) (JEOL 3000F; JEOL Inc., Tokyo, Japan). A representative TEM image of particles is shown in Supplementary Figure S1(B). Detailed AgNP characterization results for in vivo exposures are previously reported (Seiffert et al. 2016).