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Constitutive Host Resistance
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The exact mechanism by which the pseudopods surround the particle is only partially understood. Nonetheless it is clear that the contact of the particle with the phagocyte′s membrane activates actin-binding protein in the cytoplasm. These proteins promote the assembly of actin molecules and gelation of the actin in the cytoplasm underlying the attachment site. Myosin binds to polymerized actin and then the molecules contract, producing movement of the pseudopods around the particle being engulfed. Orientation of the microfilaments and their points of attachment to the cell membrane determine the form and direction of pseudopodial extension. The pseudopod moves around the particie by a series of reactions initiated by additional membrane-particle contact (Figure 3.4). Once a microbe or other particle is within the cell, it is surrounded by the cell membrane that lines the phagocytic vacuole or phagosome.
Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
Another type of cell found in connective tissue is the macrophage. It is known by a variety of names such as clasmatocyte and histiocyte. The macrophage has been postulated to be derived from the monocyte. The life span may be 2 to 3 months, depending on the tissue. Macrophages can be identified by vital staining, an excellent method demonstrating macrophages “in action”. Ultrastructurally, macrophages have an irregular shape. Their cell membrane has been modified into finger-like projections or pseudopods. The nucleus is indented and common organelles such as mitochondria and a small amount of rough endoplasmic reticulum are present. Macrophages contain numerous types of lysosomes with pinocytotic and phagocytotic vacuoles. The function of macrophages is to engulf and destroy bacteria or foreign substances, and to process antigens for presentation to the immune system. The functional activity of a macrophage can be appreciated by the complexity of its membrane modifications.38,202,204
Sperm Chemotaxis
Published in Claude Gagnon, Controls of Sperm Motility, 2020
Unlike neutrophils, which move only when stimualted by an attractant, both bacteria and spermatozoa are motile in the absence of attractant and the presence of a gradient of attractant only modulates locomotor behavior. Also in both cases also locomotion is achieved through the motion of flagella, although they are of totally different structures and mode of function. Other cells, which demonstrate chemotactic behavior, migrate by pseudopod extension with preferential pseudopod formation toward the higher chemoattractant concentration. Bacteria such as E. coli swim by rotating their flagellar filaments. Forward swimming is generated by counterclockwise (CCW) rotation, whereas random turns or tumbling results from clockwise (CW) rotation. Favorable stimuli enhance CCW, unfavorable stimuli enhance CW, or tumbling cause the bacteria to reorient and swim in a new random direction.160
Leptin Promotes Prostate Cancer Proliferation and Migration by Stimulating STAT3 Pathway
Published in Nutrition and Cancer, 2021
Amal Gorrab, Alessandra Pagano, Khouloud Ayed, Mohamed Chebil, Amine Derouiche, Hervé Kovacic, Asma Gati
To analyze the impact of leptin on the epithelial-mesenchymal transition (EMT), an important process during tumor development by which epithelial cells acquire mesenchymal phenotype, we examined the morphology of cells and E-cadherin expression after treatment with 100 ng/ml of leptin. As shown in Figure 3(a), leptin treated DU-145 exhibit morphological differences when compared with untreated cells. The phenotypic changes included the acquisition of fibroblast-like appearance, theincreased formation of pseudopodia emanating from the cell membrane, the dissolution of cell-cell junction and the loss of apical-basolateral cell polarity. Additionally, leptin treated DU-145 cells downregulate E-cadherin expression. Treatment with AG490 inhibits morphological changes on leptin treated DU-145 cells and enhances upregulation of E-cadherin (Figure 3(b)). Totally, these results argue that leptin could enhance PC cells EMT.
Facile surface functional polyetheretherketone with antibacterial and immunoregulatory activities for enhanced regeneration toward bacterium-infected bone destruction
Published in Drug Delivery, 2021
An’an Sun, Xi Lin, Zhiqiang Xue, Jiyue Huang, Xinxin Bai, Lingling Huang, Xinhua Lin, Shaohuang Weng, Min Chen
The cell viability on different PEEK samples was further studied to evaluate the in vitro biocompatibility and osteogenic differentiation of SPEEK–pDA–GS. SEM images (Figure 4(A)) showed that the cells adhered well on different groups of samples. The cells were fusiform on the natural PEEK and did not expand completely. When cultured on SPEEK, SPEEK–pDA, and SPEEK–pDA–GS, the morphologies of MC3T3-E1 and RAW264.7 expanded completely. In addition, many cellular pseudopodia were found on the surfaces of the three modified PEEK samples. Furthermore, the both MC3T3-E1 and RAW264.7 of the SPEEK, SPEEK–pDA, and SPEEK–pDA–GS groups were more closely interconnected and cross-sectional than those cells of the natural PEEK group. This result suggested that the modification of pDA and GS did not inhibit the growth but promoted the flat diverse distribution of cells on modified PEEK samples. Furthermore, the SEM image of cells inoculated for 24 h on different surfaces indicated that the adhesion of bone cells and macrophages to the modified PEEK was better than that to the pure PEEK. In addition, compared with those on the natural PEEK, the RAW 264.7 cells on the modified PEEK samples seemed to be spread more evenly and more diversely (Figure 4(A)), suggesting the specific inducement effect of porous surface structure (Liu et al., 2019; Wei et al., 2019).
Dual variable of drug loaded micelles in both particle and electrical charge on gastric cancer treatment
Published in Journal of Drug Targeting, 2020
Xiu-ying Li, Jian-hua Wang, Li-yan Gu, Xue-min Yao, Fu-yi Cai, Ming Jing, Xue-tao Li, Rui-jun Ju
With the continuous growth of carcinoma, the blood vessels in tumour area are gradually enriched, and tumour cells begin to deform or form pseudopods. Soon, tumour cells fall off to form free cells and metastasise to the distal end. In the process of cell deformation and movement, epithelial cell mesenchymal transition (EMT) plays an important role [47]. Tumour cells acquire a mesenchymal cell phenotype under a variety of inducing factors, and their ability to move and invade is significantly enhanced [48,49]. During the EMT process, the secretion of matrix metalloproteinases (MMPs) in tumour cells increased significantly, thereby destroying the extracellular matrix to facilitate the deformation and invasion of tumour cells. As shown in Figure 7, the EMT phenomenon of paving stone-like or spherical BGC-823 cells was simulated by heating, and most of tumour cells had a fusiform shape after heating. HA/CPP modified paclitaxel with tetrandrine micelles + HAase significantly inhibited the morphological changes of tumour cells, and this could be explained by the down-regulation of MMP-2.