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Intestinal Failure
Published in Praveen S. Goday, Cassandra L. S. Walia, Pediatric Nutrition for Dietitians, 2022
Rashmi Patil, Elizabeth King, Jeffrey Rudolph
Assessment of a patient’s nutrition status first requires a thorough understanding of individual anatomy, especially with short bowel syndrome. Different parts of the gastrointestinal tract are responsible for the absorption of specific nutrients. A longer residual bowel length is generally associated with a greater ability to undergo sufficient intestinal adaptation leading to enteral autonomy. An estimate of the length of remaining bowel is the critical factor in assessment. As total bowel length differs based on patient age/size, expressing remaining bowel length as a percentage of total bowel length can often be useful.
Drug Design, Synthesis, and Development
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
Drug absorption refers to the route or mechanism by which a drug reaches the blood supply, which is also dependent on how the drug is administered. The preferred method of administration is the oral route because it is the least intrusive, hence is used most commonly. When taken orally, the drug is delivered to the gastrointestinal tract (GIT); first entering the stomach, where it is subjected to gastric juices and hydrochloric acid. These chemicals, used to digest food, will also degrade drug molecules, so for a drug to be effective orally, it must be tolerant to these conditions.
The Integumentary (Dermatologic) System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
For the topical administration of systemically active drugs, other dosage forms are available. Skin patch delivery systems, generally known as transdermal patches, have been designed to deliver drugs directly into the bloodstream through the skin. Examples of drugs administered by this route are estrogen and nitroglycerin. Certain solvents can also be used to enhance dermal absorption of drugs, and some could provide direct administration of many drugs through the skin.
Three-dimensional (3D) cell culture studies: a review of the field of toxicology
Published in Drug and Chemical Toxicology, 2023
Seda İpek, Aylin Üstündağ, Benay Can Eke
The gastrointestinal tract plays an important role in digestion, electrolyte and fluid transport, drug absorption and metabolism as well as nutrient absorption (Markus et al.2021). Intestinal permeability affects drug bioavailability (Marrella et al.2020). The small intestine, the longest segment of the gastrointestinal tract (GIT), serves as a protective barrier against pathogenic and opportunistic microbial infections (Markus et al.2021). Considering the function of the gastrointestinal tract, it is common for drugs to cause gastrointestinal toxicities (Peters et al.2019). However, the lack of in vitro intestinal tissue models that accurately reflect the architecture and physiology of the gut has hampered research on drug absorption, metabolism, and gastrointestinal toxicity. On the other hand, the physiology and the outcomes of humans cannot be predicted by animal models. Moreover, some human pathogens are species-specific, which means they cannot infect other hosts. Therefore, human intestinal tissue models resembling in vivo microenvironments and providing physiologically relevant cellular responses are needed so that pharmaceuticals and toxicants can be predictably and effectively tested (Markus et al.2021).
MPS dose reconstruction for internal emitters: some site-specific issues and approaches
Published in International Journal of Radiation Biology, 2022
Richard W. Leggett, Keith F. Eckerman, Michael Bellamy
For the most part, the biokinetic models applied in the dose reconstructions conducted to this point in the MPS are the models applied in ICRP Publication 68 (1994a). For the LANL study and for some special cases at Rocketdyne and Mound described in a later section of this article, the models of Publication 68 have been replaced with updated or site-specific biokinetic models. For most inhalation exposures at Rocketdyne, Mound, and Mallinckrodt, the applied respiratory model was the Human respiratory tract model (HRTM) introduced in ICRP Publication 66 (1994b) and applied in Publication 68. The ICRP originally provided three sets of parameter values for the HRTM describing different levels of solubility (‘absorption types’) of inhaled particles in the respiratory tract: Type F, representing fast dissolution and a high rate of absorption to blood; Type M, representing a moderate rate of dissolution and a moderate rate of absorption to blood; and Type S, representing slow dissolution and slow absorption to blood. These absorption types are referred to frequently in this article and, unless otherwise indicated, refer to their original definitions.
Association of adverse outcomes of intrahepatic cholestasis of pregnancy with zonulin levels
Published in Journal of Obstetrics and Gynaecology, 2021
Cigdem Damla Deniz, Sibel Ozler, Fatma Kubra Sayın
Damage of the intestinal barrier is one of the causes of absorption disorders, inflammation and autoimmunity. The structure, function, and regulation of the intestinal epithelial barrier are provided by tight junctions (TJ) between cells (Chiang 2011). Several autoimmune diseases, including coeliac, type 1 diabetes (Fasano 2011), rheumatoid arthritis (Mäkelä et al. 2006) and multiple sclerosis (Edwards 2008), are characterised by increased intestinal permeability and noncompetent TJ that allow the passage of antigens from the intestinal flora (Yokote et al. 2008; Groschwitz and Hogan 2009; Abreu 2010). Since it is involved in the regulation of TJ, zonulin plays a role in the passage of macromolecules and leukocytes between the intestinal lumen and blood (Fasano 2008). It has also been found that excess production of zonulin may lead to irregular paracellular transmission of antigens and challenging the immune system to produce an immune response (Fasano 2001). Serum zonulin levels have been shown to be increased in severe liver fat (Kim and Ko 2018), coeliac disease (Clemente et al. 2003) and type 1 diabetes (Watts et al. 2005).