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Physics for medical imaging
Published in Ken Holmes, Marcus Elkington, Phil Harris, Clark's Essential Physics in Imaging for Radiographers, 2021
In any given atom it is common for there to be the same number of electrons, collectively, within the electron shells as there are protons in the nucleus. This is known as an electrically balanced atom. But what happens if the nucleus and the electron shells become imbalanced electrically?If an atom gains an electron (which is a relatively common occurrence for some atoms), it is referred to as a negatively charged atom, also known as a negative ion or an anion (because it is attracted to a positive electrode or anode).If an atom loses an electron (again, relatively common) it leaves a positively charged atom, known as a positive ion or a cation (pronounced cat-ion), because it is attracted to a cathode.
The patient with acute cardiovascular problems
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
Electrolytes (salts) are substances that, when in solution, conduct an electrical current. This is because when dissolved, they separate into ions. Ions carry an electrical charge that may be either positive (cations) or negative (anions). Plasma contains extracellular electrolytes, the levels of which are carefully balanced relative to the levels in intracellular fluids. If this balance is upset, it causes major disruption to virtually all body functions. The small electrical currents generated by ions are vital for muscle contraction and nerve function. For example, low levels of potassium can result in cardiac arrhythmias and ectopic beats as the myocardium becomes more irritable. Plasma is always electrically neutral, in other words, the number of positive charges exactly balances the number of negative ones. Table 6.2 shows the common cations and anions in the body.
PlasmaThe Non-cellular Components of Blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Approximately 93% of plasma is water. The principal plasma cation is Na+ (140 mmol/L), while other important cations include K+ (4 mmol/L), Ca++ (2 mmol/L) and Mg++ (1.3 mmol/L). About one-third to one-half of the divalent cations are complexed with proteins (e.g. albumin) or low-molecular-weight anions and carry negative charges as they are on the alkaline side of their isoelectric points at a pH of 7.4. Organic acids such as lactate and pyruvate make up the remaining plasma cations.
The effects of the dietary approaches to stop hypertension (DASH) diet on oxidative stress and clinical indices of migraine patients: a randomized controlled trial
Published in Nutritional Neuroscience, 2022
Arman Arab, Fariborz Khorvash, Elham Karimi, Zahra Heidari, Gholamreza Askari
The exact mechanism regarding the role of the DASH diet in migraine headaches was not well understood. This dietary habit is loaded with lower amounts of Na, as well as higher amounts of K, Mg, and Ca. The cations play a crucial role in the functions of the central nervous system and are also involved in migraine pathophysiology [39]. Serum and cerebrospinal fluid (CSF) Na levels have been reported to increase during a migraine attack [39]. Moreover, it has been proposed that higher dietary intakes of Na can increase the content of this cation in CSF and brain extracellular fluid, subsequently reduce the threshold for action potentials [40]. This dietary plan contains fewer fried foods, refined grains, and processed meats, which were suggested to be related to lower headache frequency [41]. Also, the DASH diet is rich in anti-inflammatory and antioxidant compounds (fruits and vegetables), which could reduce neurogenic inflammation that is involved in migraine [42]. In addition, inhibition of serotonin-dependent vascular spasm, blocking of N-Methyl-D-aspartate (NMDA) receptors, and reduction of prostacyclin-dependent vasodilation were proposed mechanisms of Mg in migraine prevention [43].
Renin-angiotensin system modulators in COVID-19 patients with hypertension: friend or foe?
Published in Clinical and Experimental Hypertension, 2022
Shakhi Shylesh C.M, Arya V S, Kanthlal S. K., Uma Devi P.
Both the SARS-CoV and SARS-CoV 2 invade the host cell by binding with ACE2 receptors on the epithelial surface of the respiratory system, which is the primary target of the virus (30–32). The initial step in viral infection is viral entry into host cells. A specialized spike glycoprotein on SARS-CoV 2 binds to the ACE2 receptors present in the human airway lining and vascular endothelial cells. The S protein consists of two subunits, S1 and S2, which are responsible for receptor binding and membrane fusion, respectively. S1 subunit contains the receptor-binding domain (RBD) which allows the virus to bind to ACE2 and thus resulting in the complex/syncytia formation (25,32–36). Lim and his colleagues conducted a fragment molecular orbital method to investigate the hot spot region of the human ACE2 and SARS-CoV 2 receptor complex and they found that almost 69 amino acid pairs have been involved in the formation of the SARS-CoV 2/ACE2 complex. Cation-37). The conformational changes occurring in the surface of the SARS-CoV 2 protein tend to make it more infectious and virulent. The subunit S2 deals with the fusion between the virus membrane and the host cells. For undergoing priming of the S protein, the presence of transmembrane serine protease 2 (TMPRSS2) and ADAM metallopeptidase domain 17 (ADAM 17) is important and this facilitates the virus cells’ insertion into the host cell. The internalization of SARS-CoV 2- ACE2 results in the down-regulation of ACE2 and also upregulates ADAM17 which may help in the viral particle fusion into the cytoplasmic membrane (38,39).
Curcumin diminishes cisplatin-induced apoptosis and mitochondrial oxidative stress through inhibition of TRPM2 channel signaling pathway in mouse optic nerve
Published in Journal of Receptors and Signal Transduction, 2020
Dilek Özkaya, Mustafa Nazıroğlu
It has long been known that the patch-clamp electrophysiological technique is one of the best techniques for monitoring movement of cations through cation channels. After observing an increase of fluorescence intensity of [Ca2+]c, we wanted to further check involvement of TRPM2 channels and the effects of CURCU on the CiSP-induced Ca2+ influx in the SH-SY5Y neuronal cells. In the absence of ADPR, there was no current in the cells [Figure 3(a)]. However, we observed TRPM2 currents in the cells following cytosolic ADPR stimulation and when the channel was gated up to 0.8 nA currents [Figure 3(b)]. In CiSP groups the TRPM2 channels were further gated by the cytosolic ADPR and currents of up to 2.5 nA were achieved in CiSP groups [Figure 3(c)]. The TRPM2 currents were higher in the CiSP + ADPR groups than in the Ctr + ADPR group [Figure 3(e); p < 0.001]. The TRPM2 currents in the CURCU + CiSP + ADPR groups were decreased to 0.45 nA by the CURCU treatment [Figure 3(d)] and were lower in the CURCU + CiSP + ADPR group than in the CiSP + ADPR group [Figure 3(e); p < 0.001]. In the CiSP + ADPR, CiSP + ADPR and CURCU + CiSP + ADPR groups, the TRPM2 currents were returned to control levels by treatments of TRPM2 channel blocker (ACA) and a substitute ion (NMDG+) for sodium [Na+; Figure 3(b–d)]. Therefore, a protective role of the TRPM2 channel was further confirmed in the CiSP treated SH-SY5Y neurons by the patch-clamp electrophysiological recordings.