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Drug-Induced Autoimmunity
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Robert L. Rubin, Anke Kretz-Rommel
Semi-quantitative measurement of thymus function can be made by determining the content of TCR rearrangement excision circles (TRECs) in peripheral blood lymphocytes (PBLs). TRECs are by-products of the DNA rearrangement process required for the formation of the αβTCR and can be readily detected in recent thymic emigrants to the periphery using polymerase chain reaction (PCR) amplification across the new joint that creates the excision circle.41 Eventually the TRECs disappear from peripheral T cells due to cell division or death, so TREC levels in the periphery correlate with T cell production in the thymus.
Immune System Imaging
Published in Margarida M. Barroso, Xavier Intes, In Vivo, 2020
Michael J. Hickey, M. Ursula Norman
T lymphocytes play a critical role in the adaptive immune response, providing long-term specific immunity against microbial pathogens, while restricting inappropriate autoimmune responses. T cells initially arise from progenitors in the bone marrow. However, in contrast to many other immune cells, T cells must complete their development outside the bone marrow, in the thymus (Bhandoola et al., 2007). T cell progenitors enter the thymus from the bloodstream, where they undergo a series of selection events, while migrating through the different regions of the thymus, interacting with stromal cells and other immune cells. Only ~2% of the T cell progenitors that enter the thymus survive these stringent processes, going on to enter the circulation as naïve T cells (Sprent et al., 1996). The key step in intrathymic T cell development is recombination of T cell receptor (TCR) genes to generate a TCR. Thymocytes that express a functional TCR (capable of recognizing antigenic peptide presented on major histocompatibility complex (MHC) molecules) are allowed to survive (“positive selection”) and undergo further development. Subsequently, potentially autoreactive T cells are eliminated (“negative selection”). Thymic stromal cells play essential roles in both positive and negative selection. The thymus also supports development of cell types including γδ T cells, invariant natural killer T (iNKT cells) cells and B cells (Bhandoola et al., 2007; Klein Wolterink et al., 2010; Cowan et al., 2015; Perera and Huang, 2015; Male and Brady, 2017). However, the majority of cells that exit the adult thymus are conventional CD4+ and CD8+ αβ T cells (Akashi et al., 2000; Klein Wolterink et al., 2010; Cowan et al., 2015). As such, this section will focus on how imaging techniques have advanced our understanding of differentiation αβ T cells in this organ.
Pesticides and Chronic Diseases
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
The thymus regulates the immune system; therefore, any problems with the thymus will result in a compromised immune system. The human lymphatic disorders, in particular, dramatically increased in 2007 at the same time that almost all of the glyphosate was being used as a salt formulation.
Toxicity and human health assessment of an alcohol-to-jet (ATJ) synthetic kerosene developed under an international agreement with Sweden
Published in Journal of Toxicology and Environmental Health, Part A, 2023
D.R. Mattie, B.A. Wong, K.L. Mumy, S.M. McInturf, L.M. Shafer, R. Allen, J.T. Edwards, I. Sibomana, T.R. Sterner
At the end of exposure period for each cohort, rats were fasted for 12 hr prior to blood draw and gross necropsy by withdrawing food at the appropriate time on the day before euthanasia with ketamine/xylazine. There was no restriction of water. All animals were euthanized in accordance with current American Veterinary Medical Association (AVMA) guidelines (AVMA 2013). Following deep anesthesia, a pneumothorax was created, and the terminal blood was collected via the caudal vena cava for hematology and clinical chemistry analyses. The necropsy included examination of the external surface and all orifices, organs and tissues of the cranial, thoracic, abdominal, pelvic cavities, neck and the remainder of the carcass. Organ weights were documented for liver, right and left kidneys, adrenals, testes, epididymises, ovaries, uteri, thymus, spleen, brain, and heart. One-half of each kidney (left cut longitudinally, right cut transversely) was flash frozen and stored at−80°C until assessed for α-2-urinary (α2 u)-globulin protein.
Toxicity and occupational exposure assessment for hydroprocessed esters and fatty acids (HEFA) alternative jet fuels
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Teresa R. Sterner, Brian A. Wong, Karen L. Mumy, R. Arden James, James Reboulet, Darol E. Dodd, Richard C. Striebich, David R. Mattie
Whole body inhalation exposures were conducted 6 hr/day, 5 days/week over a 90-day period, at target concentrations of 0 (control), 200, 700 or 2000 mg/m3. Exposures were staggered 1 day to allow for 2 days of necropsy. Starting approximately 16 hr after the end of the last exposure, animals were weighed and then euthanized in accordance with the American Veterinary Medical Association (AVMA) 2007 guidelines with an overdose of sodium pentobarbital. Blood was collected via the caudal vena cava for hematology and clinical chemistries. The left testicle and epididymis were taken for sperm analysis. The necropsy included gross examination and collection of wet weights of the liver, kidneys, adrenals, testes, epididymides, ovaries, uterus, thymus, spleen, brain and heart. A standard list of tissues was collected for histopathology (U.S. EPA 1998c). Pathology observations and histopathology were conducted by a board certified veterinary pathologist.
A pilot toxicology study of biogenic silver nanoparticles: in vivo by intraperitoneal and intravenous infusion routes in rats
Published in Journal of Experimental Nanoscience, 2019
C. Ashajyothi, R. Kelmani Chandrakanth
Organ weights of rat at different concentration of Bio-AgNPs doses illustrate the effect of nanoparticles on organs. Due to the prevalence of phagocytic cells in their reticulo-endothelial system in the liver and the spleen organs, these two are most exposed organs to nanomaterials. In addition, the organs with high blood flow such as kidneys and lungs can be affected [22]. In our reports, it can be seen that the weights of the heart, liver, spleen, lung, kidneys and brain are decreased in rats treated with Bio-AgNPs at the dose range as shown in Tables 1 and 2, but not significantly reduced as compared to the control. However, the weight of the thymus is increased in Bio-AgNPs treated rat with increased concentration (in total lethal concentration) at 14th and 28th day of observation. To further consideration the organ reaction and grade of changes were examined by calculating organ index (OX) of each organ separately. The organ index for heart, liver, spleen, lung, kidneys, brain and thymus are present in Table 6.