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Applications of Green Polymeric Nanocomposites
Published in Satya Eswari Jujjavarapu, Krishna Mohan Poluri, Green Polymeric Nanocomposites, 2020
Mukesh Kumar Meher, Krishna Mohan Poluri
Serum albumin exists as a globular blood protein having an approximate molecular weight of 65 kDa. It is found in the blood of vertebrates, being especially abundant in mammal blood (Moman and Varacallo 2018). It consists of 585 amino acids which form three repetitive homologous domains and these are separated by two sub-domains in their globular structure. The most essential role of albumin is to maintain oncotic pressure in blood which is needed for proper body fluid distribution. Human and bovine serum albumins are the most studied albumins due to their obvious importance in metabolic, genetic and in vitro/in vivo clinical studies (Peters Jr 1985). Albumins are moderately soluble (up to 40% w/v) at physiological pH and perform as an excellent natural carrier for metabolic products such as steroid hormones, hemins, fatty acids, bilirubin, thyroxine and various drugs (van der Vusse 2009, Zilg et al. 1980). Albumin shows high stability in wide pH ranges from 4 to 9 and temperature up to 60°C for 10 hours of heating without any degradation/aggregation. Biodegradability and a high stability structure enable albumins to be employed as appropriate drug nano-carriers, and for encapsulating polymers in biomedical applications (Rai et al. 2017).
Drug Targeting: Principles and Applications
Published in Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani, Drug Delivery Approaches and Nanosystems, 2017
Ruslan G. Tuguntaev, Ahmed Shaker Eltahan, Satyajeet S. Salvi, Xing-Jie Liang
Unlike normal tissues, tumor tissue has high interstitial fluid pressure that hinders diffusion-mediated transport of drugs toward tumor cells. Increased interstitial pressure, especially at the center of the tumor, reduces extravasation of drugs and decreases their uptake into solid tumor. In general, high oncotic pressure pulls the fluid back from the tumor center towards the periphery, thus preventing the interaction between therapeutics with tumor cells (Heldin et al., 2004; Jain, 1987). As a result, drugs, including nanocarriers, should overcome enhanced pressure and migrate through interstitial space and reach neoplastic cells in sufficient concentration in order to be considered as successful passive targeting agents. Due to their great size, nanocarriers bearing the pharmaceutical drug are less affected by enhanced interstitial pressure (Noguchi et al., 1998; Padera et al., 2004; Swartz et al., 2007). In this regard, nanotherapeutics’ size can be concluded as one of the most important parameters in passive targeting. Indeed, the particle size has a crucial importance in both the interstitial and vasculature transport and extravasation. For successful extravasation, the size of the material should be smaller than the usual cut-off of the fenestrations in the neo-vasculature, which size usually ranges from 100 nm to 2000 nm and depends on the type and stage of the cancer (Haley et al., 2008; Hashizume et al., 2000). Moreover, large particles can be eliminated from the blood stream by spleen and liver more rapidly. On the other hand, small nanoparticles can be inactivated by kidneys (Sun et al., 2014). In addition, small agents will be able to rapidly diffuse back from interstitial space into the vascular compartment due to enhanced interstitial pressure (Dreher et al., 2006). Overall, it was found that the most optimal particle size in passive targeting ranges between 30 and 200 nm (Jain et al., 2010).
Effects of low load exercise with and without blood-flow restriction on microvascular oxygenation, muscle excitability and perceived pain
Published in European Journal of Sport Science, 2023
Mikkel I. Kolind, Søren Gam, Jeppe G. Phillip, Fernando Pareja-Blanco, Henrik B. Olsen, Ying Gao, Karen Søgaard, Jakob L. Nielsen
Notably, no difference in Δ[cHb] was observed between the LL-BFR and LL-FF protocols at task failure in contrast to the study hypothesis. Overall, these data suggest a modest level of blood-pooling within the working musculature in the present study compared to what have previously been reported in response to full arterial BFR. (Kacin & Strazar, 2011). This is surprising, as it is generally accepted that the use of partial BFR cuff pressure results in full venous occlusion but only reduced arterial inflow, in turn leading to blood-pooling distally to the cuff (Patterson et al., 2019). Together these data indicates that the present LL-BFR exercise protocol elicited high local microvascular pressure and/or contraction-induced increases in intramuscular pressure, resulting in cessation of arterial inflow and/or enabled venous return despite the application of external cuff-mediated BFR. The importance of muscle contraction in this cascade of events is supported by the present data, showing an increase in [cHB] during the 30-sec rest period after LL-BFR exercise (with cuff pressure maintained). This increase was significant for both muscles, but only during LL-BFR. Previously, similar changes in VM [cHB] have been observed between sets of LL-BFR exercise performed to task failure (Ganesan et al., 2015). Interestingly, these observations could explain the abundant tissue swelling previously observed acutely (0-180 min) in response to LL-BFR exercise (Farup et al., 2015; Yasuda et al., 2012). High microvascular pressure would likely trigger an increase in microvascular filtration, and in combination with intensive muscular contractions (cf. intra-/extracellular accumulation of metabolites) reduce plasma oncotic pressure altogether resulting in interstitial edema. Such changes likely lead to limited transcapillary diffusion, intracellular accumulation of metabolites, and cellular edema/swelling. BFR-mediated cellular swelling has previously been proposed to represent an independent myocellular anabolic stimulus, as cellular swelling has been shown to elevate and depress myocellular protein synthesis and/or degradation, respectively (Loenneke et al., 2012).