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Functions of the Liver
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
The cells are polygonal in shape and have three surface types: one facing the space of Disse and sinusoid, a second facing the bile canaliculi and a third facing adjacent hepatocytes. Microvilli project from the surfaces in contact with the sinusoids and the bile canaliculi. These microvilli increase the surface area of the cell for active secretory and absorption functions.
Cryptosporidium and Bile Duct Injury
Published in Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso, The Pathophysiology of Biliary Epithelia, 2020
Xian-Ming Chen, Nicholas F. LaRusso
Although Cryptosporidium does not infect intestinal tissue beyond the most superficial surface epithelia, infection of intestinal epithelia by the organism usually produces a range of abnormalities in crypt and villous architecture including villous atrophy and crypt hyperplasia, usually accompanied by a mixed inflammatory cell infiltrate within the lamina propria.27,44 Pathophysiologically, C. parvum-induced diarrhea is associated with impaired intestinal absorption and enhanced secretion.2,45 An enterotoxin-like activity has been detected in fecal extracts from humans infected with C. parvum and may cause abnormal absorption/secretion and impaired epithelial permeability, but these findings are controversial.27 The organism attaches intimately to the microvillous membrane surface and consequently resulting in loss of microvilli and effacement resulting in malabsorption. Epithelial cell apoptosis will further damage the intestinal epithelial barrier and contribute to absorptive dysfunction.46,47Cryptosporidium invasion of host epithelial cells is also associated with host cell cytoskeletal reorganization,37,38,40,41 potentially leading to further cell dysfunction such as disruption of tight junctions between epithelial cells.
Three Reasons Supplements Will Not Benefit Most People
Published in David Lightsey, The Myths about Nutrition Science, 2019
Most of the digestion and absorption of food and its nutrients into the bloodstream occurs in the small intestine. According to research results reported in 2014 in the Scandinavian Journal of Gastroenterology titled “Surface Area of the Digestive Tract—Revisited,”17 the small intestines diameter is 1 inch or 2.5cm, its length is 10 feet or 3.05 meters. Researchers determined the unique projections and folding’s of the villi and microvilli, which line the small intestines absorptive surface area, “amplify the small intestinal surface area by 60–120 times,” illustrating the highly complex and efficient capacity of the small intestines to regulate the absorption of nutrients by two-fold to four-fold. This can vary dramatically, depending upon need, availability, and negative interactions with other nutrients taken in excess, which may impede a nutrients absorption. As an example, large quantities of zinc, such as from a supplement, can interfere with copper bioavailability.18
Experimental and computational models to investigate intestinal drug permeability and metabolism
Published in Xenobiotica, 2023
Jinyuan Chen, Ziyun Yuan, Yifan Tu, Wanyu Hu, Cong Xie, Ling Ye
The intestine is the main site of drug absorption in the human body. A variety of cells, transporters, carrier proteins, and enzymes are distributed in the intestine. The main cells responsible for intestinal absorption and metabolism are enterocytes, which possess numerous microvilli. These microvilli greatly expand the surface area for drug absorption (McConnell et al. 2009). Several efflux and uptake transporters are distributed along the basolateral and apical sides of enterocytes, which regulate the intracellular drug concentration. Other intestinal cells (enteroendocrine cells, goblet cells, columnar intestinal stem cells, and Paneth cells) do not directly participate in absorption and metabolism, but they do indirectly affect drug absorption and metabolism. For example, mucus secreted by goblet cells, not only regulates the intestinal pH, but also filters out small molecules for easier absorption (Herath et al. 2020). Thus, the cell type and composition (e.g. intestine vs. colon) of intestinal models will lead to different absorption and metabolism properties. In addition, drug absorption and metabolism are not simply undertaken by specific cells. Complex intercellular interactions also play a role, which provides the greater adaptive capacity to the intestine (Yin et al. 2019). However, these complicated interactions mean that more sophisticated models are required, which equates to increased time and labour. Relatively simple and facile models, which often lack cell diversity and three-dimensional structures, provide less realistic results.
Effect of erythromycin on the ultrastructure of human macrophages exposed to cigarette smoke extract in vitro
Published in Ultrastructural Pathology, 2022
Shaoshuang Wang, Jianjun Huo, Yanlin Wei, Mei Huan, Zhouling Luo, Meihua Li, Mingzhi Wen, Xiaoning Zhong, Zhiyi He, Nan Ma, Jufeng Qiu, Xiaojuan Tang
Abnormal changes in the cellular ultrastructure of macrophages in the CSE group were apparent. However, following treatment with EM, the abnormal ultrastructure of the CSE+EM group had almost returned to normal. The general ultrastructure of human macrophages is displayed in Figure 1. In the control group (Figure 1A) the majority of the cells were rounded or oval-shaped, with a small number of mitochondria and lysosomes, and the rough endoplasmic reticulum (ER) was visible. Microvilli-like projections were present on the majority of the cell surface. The nucleus was eccentric, circular, oval or kidney-shaped, (there were few irregularly-shaped nuclei), and the chromatin was concentrated at the nuclear membrane. In the CSE group (compared with the control group), not only had the number of lysosomes, mitochondria and vacuoles increased, as well as an increase in the ER network, but the cellular ultrastructure was also altered; this included mitochondrial swelling and vacuolization, lysosomal gathering, expansion of the rough ER, and the aggregation of electron-dense granules. Additionally, the chromatin was concentrated in the nucleus (Figure 1B).
Redox modulatory protective effects of ω-3 fatty acids rich fish oil against experimental colitis
Published in Toxicology Mechanisms and Methods, 2019
Mohita Sharma, Ramanpreet Kaur, Kuldeep Kaushik, Naveen Kaushal
To obtain an accurate picture of DSS induced lesions and protective effects of FO (if any), ultrastructural studies were performed with the help of scanning electron microscope at magnification 370× and 500×. The mucosal surface of colon in FO and CO groups (Figure 5(A,B)) appeared to be subdivided by well-defined concave grooves, and regular-shaped crypt openings containing mucin like material. Microvilli are regular and goblet cells are interspersed among enterocytes and appeared as small point like and slightly depressed cavities. On the contrary, the DSS + CO group (Figure 5(D,F)) showed degenerated epithelium, severe inflammatory cell infiltration, widened grooves, dilatations of glandular crypts losing their regular shape by assuming fissure like aspects and depletion of goblet cells, leaving an irregular crater like area were evident. Supplementation with FO, following DSS treatment (Figure 5(C,E)) significantly restored the architecture of the colon epithelium with a marked decrease in inflammatory cell infiltration compared with the DSS + CO group animals.