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Host-Parasite Relationships
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
These examples illustrate the role of host resistance in host-parasite relationships. Studies on individuals infected with diseases such as acquired immune deficiency syndrome (AIDS), which weakens or destroys host resistance mechanisms, and of medical treatments that permit graft acceptance or destroy tumors but also weaken the host defense mechanisms has shown clearly the degree to which host-parasite interaction is a dynamic equilibrium. When host resistance is impaired, organisms that are normally present may cause disease (Figure 2.3).
Nuclear Medicine Imaging and Therapy
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
David Towey, Lisa Rowley, Debbie Peet
The 99Mo decays with a half life of 66 hours to 99mTc and so without elution, the amount of 99mTc within the generator is in dynamic equilibrium. In normal use, the generator is eluted daily. The 99Mo is usually replaced on a weekly or fortnightly basis as the eluted activity falls (Figure 5.4). Some 99Mo is found in the eluate, and Quality Control (QC) checks are required to ensure there is minimal “breakthrough” of the 99Mo and any aluminium. These checks are usually performed on the first elution of a generator, or if the generator is moved.
Disorders in tHemostasis System and Changes in the Rheological Properties of the Blood in Ischemic Heart Disease and Diabetes Mellitus Patients
Published in E.I. Sokolov, Obesity and Diabetes Mellitus, 2020
The erythrocytes of healthy persons have a high thromboplastic, heparin and antiheparin, fibrinolytic and antifibrinolytic activity. These parameters are in dynamic equilibrium and are hemostasis regulators. With an increased activity of blood coagulation, the coagulation activity of the erythrocytes lowers, and vice versa [142, 211, 255, 322, 335, 485].
Going Back to Normal
Published in Issues in Mental Health Nursing, 2021
At first glance, the concept of homeostasis seems to support the notion that we can avoid change. Homeostasis, from the Greek words for "same" and "steady," refers to any process that living things use to actively maintain fairly stable conditions necessary for survival (Rodolfo, 2000). If homeostasis is successful, life continues; if unsuccessful, disaster or death ensues. The stability attained is actually a dynamic equilibrium(often depicted as scales in balance), in which continuous change occurs yet relatively uniform conditions prevail. Any system in dynamic equilibrium tends to reach a steady state, a balance that resists outside forces of change (Rodolfo, 2000). The control of body temperature in humans is a familiar example of homeostasis in a biological system (Sadava et al., 2009). The human body maintains steady levels of temperature and other vital conditions such as the water, salt, sugar, protein, fat, calcium, and oxygen contents of the blood (Sadava et al., 2009).
Verification of a dose rate-responsive dynamic equilibrium model on radiation-induced mutation frequencies in mice
Published in International Journal of Radiation Biology, 2019
Yuichi Tsunoyama, Kazuyo Suzuki, Miwako Masugi-Tokita, Hiroo Nakajima, Yuichiro Manabe, Takahiro Wada, Masako Bando
In the field of the radiation safety protection and legal regulations, it is assumed based on the LNT model that the risk of cancer or the genetic effect would occur even in the case of very low dose exposure. From the viewpoint of the safety management, risk assessment using the LNT model is concise, easy to understand and have a certain rationality. However, such assessment by the LNT model is quite different from the fact, since it is completely ignored well-known mechanisms to eliminate abnormalities in living organisms. The LNT model does not take into account homeostasis which is essential for all organisms. Most of mechanisms related to metabolisms and biological reactions are always in dynamic equilibrium. At least in the low dose and low dose-rate exposure, various mechanisms for maintaining the biological functions and morphologies in organisms should be considered. If it is presupposed that such mechanisms are inherent in the body, it seems reasonable to make a risk assessment that emphasizes the dose-rate rather than the total dose of exposure.
Impact of laparoscopy on the biological behavior and gene expression of endometrial adenocarcinoma cells
Published in Gynecological Endocrinology, 2017
Shouguo Huang, Jie Qin, Jin Chen, Hong Cheng, Qiu Meng, Jing Zhang, Haiyan Wang
In normal conditions, the internal environment and microenvironment of the human body are in a dynamic equilibrium, which can be broken by various stimulators. The artificial pneumoperitoneum state and application of the surgical instruments during laparoscopy render the body to be under stress, leading to changes in the microenvironment. This further results in the production and release of various cytokines, which can trigger a cascade of reactions including changes in the intracellular ions, and the enzyme activity, finally resulting in changes in cell functional status and apoptosis [4,5].