The embryonic period
Frank J. Dye in Human Life Before Birth, 2019
Gastrulation and neurulation occur during the early embryonic period. Both of these processes involve cell movements, including invagination, evagination, epiboly, involution, convergence extension, migration, and ingression. Invagination is the movement of a sheet of cells into a preformed cavity. Evagination is the movement of a sheet of cells away from a preformed cavity, for example, the evaginations of the developing retinas from the lateral walls of the early forebrain. Epiboly is the spreading of cells upon a surface. Involution is the turning in of cells over a rim, for example, the involution of epiblast cells into the primitive streak. Convergence is the movement of cells toward each other. Extension is the elongation of a structure as a result of cell convergence. Migration is the movement of single cells, for example, the movement of neural crest cells throughout the developing embryo to give rise to a wide diversity of structures, such that the neural crest has been referred to as the fourth germ layer. Ingression is the movement of single cells out of a cell layer into a preformed cavity, for example, ingression of epiblast cells along the primitive streak to give rise to endoderm and mesoderm, or formation of the notochord by cells that ingress through the primitive (Hensen's) node.
The Thymus Gland
Nate F. Cardarelli in Tin as a Vital Nutrient:, 2019
Using a somewhat more scientific approach, Collin and Lucien developed a table of ratios of body weight-to-thymus weight in the human fetus and young infants.19 Importantly, they noted that involution occurs with various physical maladies. Bovaird and Nicoll, in an elaborate study of 571 autopsies of children ranging in age from 0 days to 5 years, weighed all the viscera, although emphasis was on the thymus.20 Unfortunately, their subjects were from the New York Foundling Hospital where, in 1906, poor diets and disease would be commonplace. However, probably the foremost world authority on the thymus over the period 1900 to 1930 correctly deducted the flaw in the earlier studies. His subjects consisted only of healthy humans dying accidental deaths.21 His values of 12 g at birth, 25 g at 3 years, 30 g by puberty, and 15 g at senility were reasonably accurate for average gland weight, but did not take into account the respective dilution of such tissue with fat. Fairly accurate fetal thymic weights as a function of whole body weight were reported in 1909.22
Normal and Pathological Language in Elderly People
José León-Carrión, Margaret J. Giannini in Behavioral Neurology in the Elderly, 2001
Slowing down is the evolutionary counterpart of response and processing speed and alters the computational efficiency of the system in a special way. It implies the involution of cognitive functions,37 understood as the disorganization or destructuring of complex processes that have been built up during the course of development. This destructuring does not have to follow an exactly inverse pattern to its construction. The involution process can be diverse and refers to certain aspects of development, especially those related to processing efficiency. The language system has been evolving during development, creating and perfecting very complex and hierarchical subsystems. During the involution process the system progressively loses, and in an inverse direction, the complexity previously acquired. Thus, the more complex and sophisticated aspects of the system deteriorate first, while the less complex and simpler aspects remain intact.
Retinoic acid-related orphan receptor gamma t (RORγt) inverse agonists/antagonists for the treatment of inflammatory diseases – where are we presently?
Published in Expert Opinion on Drug Discovery, 2021
Nevertheless, as outlined above, many recent clinical trials have been terminated for safety reasons detected in humans in clinical trials or in preclinical experiments performed in parallel to clinical trials. It was found that RORγt knockout or inhibition impacts TH17 differentiation, IL-17 transcription and thymocyte maturation to similar extent. Genetic Rorc deficiency in mice, while preventing autoimmunity, causes early lethality due to metastatic thymic T cell lymphomas and it was possible to excerpt same effects with potent RIAs in mice and rats (one rat showed thymic cortical hyperplasia after oral administration of a potent RIA for 13 weeks [29]). Thymic lymphomas were also detected in the 6-month carcinogenicity study with BMS-986251 [46], which was potentially the reason for termination of the clinical trial. It remains questionable whether the susceptibility to thymic lymphomas is somehow unique to rodents, however there is still a translational risk to humans [29,116]. Nevertheless it should be considered that by the early teens, the thymus undergoes involution where it becomes quite nonfunctional in adults. This may offer the potential to treat individuals of a certain age without concern for thymic lymphomas.
The PHACES syndrome: Multiple episodes of reproliferation of subglottic hemangioma
Published in Baylor University Medical Center Proceedings, 2018
Randall W. Holdgraf, Melissa Kress
Infantile hemangiomas are the most common benign tumors of infancy. They are characterized by two distinct phases: proliferation and involution.1 The proliferation phase is characterized by rapid growth for the first 6 to 9 months of life followed by involution over 3 to 7 years.2 Most hemangiomas occur in otherwise healthy infants; however, almost one third of patients with hemangiomas >22 cm2 also have PHACES syndrome, which stands for posterior fossa, hemangioma, arterial anomalies, cardiac defects, eye abnormalities, and sternal cleft.3 PHACES syndrome is diagnosed by the presence of a facial hemangioma >5 cm in diameter plus one major or two minor criteria involving these systems.4 Children with PHACES syndrome can also be afflicted by subglottic hemangiomas, which commonly present with biphasic stridor worsened by crying. Progression of subglottic stenosis can lead to significant airway obstruction necessitating aggressive medical and surgical treatment.5 Treatment of airway hemangiomas with propranolol has been well described and shows promising results; however, there are still cases of either failure to respond to propranolol treatment or recurrence after discontinuing therapy.6,7 Herein, we describe a particularly challenging-to-treat patient with PHACES syndrome and subglottic hemangioma who had multiple recurrences once propranolol treatment was weaned.
Low-intensity ultrasound promotes uterine involution after cesarean section: the first multicenter, randomized, controlled clinical trial
Published in International Journal of Hyperthermia, 2022
Yi Qin, Xiaobo Zhao, Xiaojing Dong, Juntao Liu, Longqiong Wang, Xiaohua Wu, Bin Peng, Chengzhi Li
Ultrasound therapy is widely used in clinical practice as a new noninvasive treatment technology, and its effectiveness and safety have been proven [13–15]. As shown in mouse models, Low-intensity ultrasound (LIUS) promotes the contraction of uterine smooth muscle and can increase the frequency and amplitude of spontaneous uterine contractions [16]. Nizard et al. showed that high-intensity focused ultrasound exposure of the postpartum uterine arteries in ewes reduced the diameter of the target vessel, resulting in a slowing of blood flow downstream of the vessel. The above research suggested that ultrasound can cause vascular smooth muscle to contract, which may play a role in postpartum hemorrhage [17]. Nevertheless, the clinical benefits of LIUS on human uterine involution have received less attention. In this study, we evaluated the clinical efficacy and safety of LIUS in promoting uterine involution and alleviating postpartum pain by directly measuring the fundal height following LIUS treatment and recording the duration of lochia and the score changes in the visual analogue scale (VAS). Overall, this study aimed at providing an insight into the clinical treatment of postpartum uterine involution.