The Protozoa
Donald L. Price in Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
The cytoplasm has two components, the outer tougher and more hyaline ectoplasm that forms the outer layer of amoebae (and other protozoa) and the inner, more fluid component, the endoplasm, that is granular and contains many of the organelles and any inclusions. In Plate 36:1, a clear pseudopodium of ectoplasm stretches out and, when actively motile, the amoeba flows into it. For food gathering, the pseudopodium simply surrounds its prey and draws it inside where it is surrounded by the cytoplasm and transferred to a vacuole such as the one surrounding the red blood cell in the drawing. The ingested material is digested while in the vacuole (see the smaller included body in a vacuole, Plate 36:1) and the wastes are extruded in much the same manner as the prey was included only in reverse.
Free Radicals and Antioxidants
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Manganese (Mn) is an essential micronutrient and a trace metal that intervenes in the activity of superoxide dismutase within the mitochondria (111, 214–215). Superoxide dismutase (SOD) is a metalloenzyme and antioxidant enzyme. SOD contains metal such as manganese, copper, zinc, or iron, used as cofactor for the enzyme’s functioning. SOD protects cells from reactive oxygen species (ROS) by decomposing superoxide radical O2.- into molecular oxygen (O2) and hydrogen peroxide (H2O2) by cyclic oxidation and reduction reactions with the active site metal (214–215). In humans, there are three forms of SODs: SOD-1, SOD-2, and SOD-3. SOD1 and SOD3 contain copper and zinc and are located in the cytoplam and the endoplasm, respectively. As for SOD-2, it contains manganese as cofactor and is located in the mitochondria. SOD-2 or Mn-SOD is of great interest to the medical field because of its protection against the deleterious effects of excessive superoxide in disease states (214). Decreased levels of SOD-2 may contribute to the development of certain diseases such as neurodegenerative diseases (Parkinson’s disease and amyotrophic lateral sclerosis), diabetes, and cancer (214–215). Mn deficiency in the body leads to the inactivation of SOD-2 antioxidant enzyme. However, chronic exposure to Mn causes manganism, a manganese poisoning that is a classic ‘pro-oxidant’ disease.
Section V
Evan A. Evans, Richard Skalak in Mechanics and Thermodynamics of Biomembranes, 1980
Our next discussion deals with the compression of sea urchin eggs between two flat surfaces. Unlike the mammalian red blood cell which normally has a liquid cytoplasm, the sea urchin egg interior is more complicated. Indeed, its membrane is closely associated with a cortical layer or shell which probably contributes to its mechanical rigidity. It is still appropriate to model the constitutive behavior of the complicated membrane-cortex by the anisotropic (two-dimensional) surface elastic relations that were developed in Section IV. We make the assumption that the membrane-cortex is responsible for the elastic solid behavior of the unfertilized sea urchin egg when it is exposed to external forces over long time periods (e.g., greater than 1 min in duration). [For such time periods, it appears that the endoplasm is essentially viscoplastic and cannot support stresses other than hydrostatic pressure (Hiramoto, 1970).]42 Since the thickness of the membrane and cortex of the egg are less than 10% of the radius of curvature of the egg, we will treat the force equilibrium with the equations of thin shell theory. In other words, the forces applied to the egg are primarily balanced by the force resultants that act in the plane of the shell, i.e., by tensions. The bending moments and other stress resultants produce second order contributions, but may be important in situations where curvature changes are appreciable.
The broad-spectrum antiviral recommendations for drug discovery against COVID-19
Published in Drug Metabolism Reviews, 2020
Abu Hazafa, Khalil ur-Rahman, Ikram-ul- Haq, Nazish Jahan, Muhammad Mumtaz, Muhammad Farman, Huma Naeem, Faheem Abbas, Muhammad Naeem, Sania Sadiqa, Saira Bano
The coronavirus replication cycle starts after the entry of virus into the host cell, the replication cycle initiates with the translation of viral genome at 5′-proximal open reading frames (OLFs) including ORF1a and ORF1b, which resultingly syntheses two large replicase polyproteins namely pp1a and pp1ab as illustrated in Figure 3. The formation of polyprotein, pp1ab, at the C-terminal domain involves a –1 ribosomal frameshift (RFS) into ORF1b near the 3′ end of ORF1a. This is the principal regulatory mechanism that is responsible for downregulating the expression level of ORF1b-encoded proteins in contrast to ORF1a-encoded nonstructural proteins. Both polyproteins (pp1a and pp1ab) cleaved with the help of several internal proteases (TMPRSS2) (see Supplementary Material; Abbreviation), and resulted in the assembly of viral nonstructural proteins (nsps) in the form of RTC (de Wilde et al. 2017). The proteolytic cleavage of both polyproteins (pp1a and pp1ab) by internal ORF1a-encoded proteases fallouts in the 15 mature replicases proteins. These replicase proteins comprise several types of enzymes, including helicase (nsp 13), exoribonuclease (nsp 14), RNA-dependent RNA polymerase (nsp 12), and RNA cap-modifying methyltransferases (nsp 14 and 16) which helped in the enzymatic activities and functions, necessary for viral RNA synthesis and capping (Snijder et al. 2016). Finally, after the replication and transcription, the viral genome is packed into nucleocapsids (enveloped from smooth endoplasm reticulum by budding) and ultimately leave the cell through the exocytic pathway (Ulasli et al. 2010; de Wilde et al. 2017).
Optimization and kinetic modeling of interchain disulfide bond reoxidation of monoclonal antibodies in bioprocesses
Published in mAbs, 2020
Peifeng Tang, Zhijun Tan, Vivekh Ehamparanathan, Tingwei Ren, Laurel Hoffman, Cheng Du, Yuanli Song, Li Tao, Angela Lewandowski, Sanchayita Ghose, Zheng Jian Li, Shijie Liu
Glutathione (GSH)/glutathione disulfide (GSSG) is the most important redox pair in the endoplasm reticulum (ER), where antibody is synthesized, folded, and assembled.28 Previous in-vitro experiments demonstrated that a GSH/GSSG ratio similar to that found in the ER could efficiently oxidize active-site cysteine in protein dimerization isomerase, which then could lead to the disulfide formation of substrate proteins.28–30 Since the intracellular disulfide formation is regulated by the redox system, we applied the same principle in an in-vitro environment. Cysteine (Cys) and cystine (Cys-Cys) have been reported as an effective combination to reoxidize reduced mAb fragments to form intact mAb.30–32 In addition, the use of these two redox components is not expected to pose any product safety concerns as both are common upstream media components. Thus, we carried out in-solution studies to evaluate the possibilities of reoxidizing the reduced mAb-1 using a redox system containing varied amounts of cysteine and cystine. GSH was included in the studies due to its wide use in process development. Factors including pH and temperature were also evaluated. The starting material was a partially reduced mAb-1 molecule containing L, HL, HH, HHL, and H2L2 (intact mAb). Figure 2 showed a typical dynamic profile of mAb species overtime in an in-vitro redox system containing cysteine/cystine pair at pH 8. This allowed us to assess the possibility of adapting the principle of intracellular redox system into the in-vitro redox system without further optimizing the redox components and pH condition. The starting material, composed of less than 5% intact mAb-1 (presented as potential worst-case scenario), was recovered to reach the final product purity greater than 95% after 24 hours at room temperature.
Leptin receptor defect with diabetes causes skeletal muscle atrophy in female obese Zucker rats where peculiar depots networked with mitochondrial damages
Published in Ultrastructural Pathology, 2021
Jacques Gilloteaux, Charles Nicaise, Lindsay Sprimont, John Bissler, Judith A Finkelstein, Warren R Payne
Among oxidative fibers subsarcolemmal mitochondrial aggregates, other poorly recognizable deposits by LM aspects were only describable through fine structure aspects. Displayed as small lipid-like deposits, these Ls were highly and uniformly electron dense contrasted and their shapes varied; smaller than the SDs and found with the electron microscope as string-like accumulations recalling those of liposomes as lined by poorly-recognized lining membrane. Only found to the narrow perikaryal and sub sarcolemmal zones of the muscle fibers, their fine structure features revealed them as if initiated near or by the small Golgi zones to form Ls (Figures 7, 10(a,b)). They also displayed interconnected oweverclumps of various shapes (Figures 6, 7, 9(a,b), 10(a)). With higher magnifications, Ls revealed a unit membrane lining with crenate aspect (Figures 6, 8(c,d)). In some oblique or tangential sections, the electron micrographs made up them of some aligned, interconnecting circular channels along their lining membranes, including those that contacted the outer membrane of the mitochondrial envelope (Figure 8(a-d)). In some cases, Ls were noted with a sort of hexagonal profile (Figure 8(d)) among a filled to swollen homeomorphic endoplasm network (Figure 8(b)). Therefore, these Ls differed from the aforementioned SDs, those lacked lining membrane. In addition, the network of smooth endoplasm structures with electron contrasted content associated with the outer membrane’s of the mitochondria envelopes through linkages or blunt conduits in continuity and their dense content of the intermembrane space, the inner membrane and the mitochondrial matrix (Figures 6 and 9(b)). Enlargements of some parts revealed in Figure 8(e,f) provide further details of the crenated lining of the Ls and its reticulum-containing complex that appeared to demonstrate elongated channel-like, resembling those found in vitro and in vivo, with lipids and phospholipids enriched by ceramides.