Macronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Fibrous or fibrillar proteins are filiform, long and physically tough. They are mainly of animal origin and are insoluble in all common solvents such as water, acid, alkali solution and organic solvents. Fibrous proteins have structural and protective functions. The fibrous proteins are extremely strong and possess the elastomer characteristics. It is a heterogeneous group and includes the keratins and the proteins of connective tissues found in bones, skin, hair, nails, horns, hoofs, wool, and silk (36, 47). The important examples are: collagens, elastins, keratins, and fibroins. Collagens and their analogs elastins are the proteins of connective tissues, skin, cornea of the eyes, tendons, cartilages, and ligaments. They are also called ‘cellular glue’ as they help give tissues their shape and keep them strong, and are the major proteins of white connective tissues (tendons, cartilage) and of bone. Due to its abundance, strength and its directly proportional relation with skin aging, collagen has gained great interest in the cosmetic industry (51). Elastin has the additional property of being elastic as a rubber band (47). Keratins are rich in cystine, a sulfur amino acid, and are the major components of skin, hair, feathers, hoofs, nails, and horns (47). Fibroins are mainly composed of amino acids; glycine, alanine, and serine and are found in the fibers of silk (47). Fibrin is the protein formed when blood clots.
Actions of Dopamine on the Skin and the Skeleton
Nira Ben-Jonathan in Dopamine, 2020
Hemostasis and coagulation: Within the first few seconds of injury, local blood vessels undergo an intense vasoconstriction aimed at minimizing blood loss. Platelets, which normally circulate in blood in an inactive (quiescent) form, are recruited to the wound site and become activated (Figure 11.3). Activated platelets release chemical signals that trigger the coagulation cascade. Subsequently, the platelets induce clot formation by converting on their surface prothrombin into thrombin, a serine protease enzyme. Thrombin converts fibrinogen, a soluble plasma protein, into the insoluble fibrin. At the injury site, fibrin forms a mesh of fibers and acts as an adhesive that binds the platelets to each other. The resulting clot plugs the break in the blood vessel, slowing/preventing further bleeding. Additional detail on the coagulation cascade is presented in Chapter 9, Section 9.5.3, Table 9.2, and Figure 9.7.
Coagulation Theory, Principles, and Concepts
Harold R. Schumacher, William A. Rock, Sanford A. Stass in Handbook of Hematologic Pathology, 2019
The purpose of the blood-clotting enzymes is the conversion of fibrinogen to fibrin, the basis of clot formation. This event, which is so simple in concept, is one of the most fascinating processes in biology. Fibrinogen is a large, complex molecule that under normal circumstances is soluble. Minor proteolysis leads to the formation of a soluble product that polymerizes spontaneously to form an insoluble mesh composed of fibrils. The nature of this change is subtle. The basic structure is a fibrous molecule that shares many characteristics with other fibrous molecules. It has a molecular weight of 340,000 and consists of three pairs of nonidentical peptide chains denoted as α, β, and γ, which are covalently linked by a series of disulfide bonds. The structure has been well characterized. It is a long chain characterized by a “dumbbell shape,” with a central globular mass at its center. Thrombin cleaves two pairs of peptide chains releasing fibrinopeptides A and B yielding fibrin monomer (57,58).
Therapeutic effects and mechanism of human amnion-derived mesenchymal stem cells on hypercoagulability in a uremic calciphylaxis patient
Published in Renal Failure, 2023
Anning Bian, Xiaoxue Ye, Jing Wang, Ming Zeng, Jiayin Liu, Kang Liu, Song Ning, Yugui Cui, Shaowen Tang, Xueqiang Xu, Yanggang Yuan, Zhonglan Su, Yan Lu, Jing Zhou, Xiang Ma, Guang Yang, Yaoyu Huang, Feng Chen, Youjia Yu, Mufeng Gu, Xiaolin Lv, Ling Wang, Jing Zhao, Xiuqin Wang, Ningxia Liang, Changying Xing, Lianju Qin, Ningning Wang
D-dimer is a plasmin-derived soluble degradation product of cross-linked fibrin, served as a valuable marker of coagulation and fibrinolysis activation. Of note, D-dimer is a sensitive indicator for detection of thrombosis, but its specificity is not ideal [24]. Fibrinogen, the soluble precursor of fibrin, is a major determinate of blood viscosity and red blood cells aggregation. Elevated fibrinogen levels may provide a hypercoagulable state through increasing the aggregation and reactivity of platelet [25]. Prior to hAMSC treatment, the patient in this case had elevated levels of plasma D-dimer and fibrinogen, indicative of an underlying hypercoagulable condition. The patient also displayed significantly elevated levels of CRP and leukocytes before hAMSC administration, indicating a high inflammatory status. Increasing evidence indicates that systemic inflammation can induce the activation of coagulation system, which may result from tissue factor (TF)-mediated thrombin generation or the dysfunction of anticoagulant pathway, such as the impaired protein C system [26]. Compared with physiological serum level of albumin, platelet aggregation was significantly higher in the presence of low serum albumin level [27]. This case had hypoalbuminaemia at the onset of hAMSC administration. Thus, either acquired thrombophilic conditions like protein C and protein S deficiency or hypercoagulability induced by inflammation and hypoalbuminaemia may be correlated with the development of CUA.
Myocardial injury after non-cardiac surgery and per operative fibrin metabolism in patients undergoing hip-fracture surgery: an observational study
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2023
Kirsten L. Wahlstrøm, Sarah Ekeloef, Ismail Gögenur, Anna-Marie B. Münster
The formation of fibrin clots represents the final step in blood coagulation. Fibrin clots composed of compact, highly branched networks with thin fibres are resistant to lysis [49]. Altered fibrin structure has consistently been reported in patients with several diseases complicated by thromboembolic events, including patients with acute or prior MI, ischemic stroke, and venous thromboembolism [50,51]. Suppression of inflammatory responses increase clot permeability and susceptibility to lysis [52]. Our study is the first to investigate the fibrin fibre properties in relation to urgent non-cardiac surgery. A recent study on elective orthognathic surgery reported a decrease in fibrin clot lysis, decreased fibrin mass-length ratio and diameter as well as increased density after surgery [53]. These properties are coherent with impaired breakdown of fibrin and thus a haemostatic system shifted towards the prothrombotic direction after surgery. However, there are several differences in the patient populations of the study on orthognathic surgery and our study. Our patients were exposed to subacute surgery, not elective procedures, our patients were older, and had noticeable cardiovascular risk factors. Additionally, the trauma our patients underwent prior to surgery might have activated the haemostatic system long before the surgical trauma.
Updates in immunocompatibility of biomaterials: applications for regenerative medicine
Published in Expert Review of Medical Devices, 2022
Mahdi Rezaei, Farideh Davani, Mohsen Alishahi, Fatemeh Masjedi
The chemical structure of a biomedical device has a considerable influence on the reorganization of the device by the immune system as a threat. In this respect, fabricating the biomaterials from natural products due to their biocompatible essence is beneficial. Natural polymers such as polysaccharides and proteins have been extensively used as highly compatible biomaterials [34]. Among the proteins, collagen is the main component of the ECM, so designing biomaterials using collagen can be beneficial for moderating the immune response, but the main obstacle has been the low mechanical properties of collagen-based biomaterials [35,36]. Gelatin is also another common protein derived from the hydrolysis of collagen, which can be used as a biocompatible device with better mechanical properties [37]. Besides its high biocompatibility, silk is another protein that possesses suitable mechanical properties [38]. Fibrin is another protein that polymerizes the soluble plasma protein fibrinogen, which acts as the thrombin for the clotting cascade [39]. Fibrin-based biomaterials mimic the structure of the blood clot so they can possess high biocompatibility [40]. Recently driving the fibrin from the patient own blood to produce a specific scaffold made a new horizon in immunomodulation [41].