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Basic Microbiology
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Free-living bacteria require protection against osmotic stresses. Osmotic stress is encountered when bacteria enter hypotonic or hypertonic environments depending on the concentration of solutes within the cell. This can lead water to cross the plasma membrane by osmosis in an attempt to normalize solute concentrations across the membrane. Excess gain of water can cause the bacteria to lyse or explode due to cellular swelling whereas excess loss of water can cause membrane rupture by excessive shrinkage (plasmolysis). Most bacteria utilize a carbohydrate-based cell wall in order to provide resistance to osmotic forces. The basis of the cell wall is a macromolecular complex unique to bacteria called “peptidoglycan” or murein (Figure 1.4). The basic repeating structure of peptidoglycan is a disaccharide comprising N-acetylglucosamine (NAG) linked to N-acetylmuramic acid (NAM). This disaccharide is repeated hundreds of times to build long carbohydrate chains that are linked together by short peptides (called stem peptides) that contain unusual amino acids, some not found in proteins. These long chains appear to be wound into helices first and then cross-linked to other helices to form the peptidoglycan structure (2). The peptidoglycan is attached firmly to the cell membrane by lipoproteins. Although bacteria have proteins that determine the overall morphology of the cell, the peptidoglycan reinforces that morphology.
Equine Semen Preservation: Current and Future Trends
Published in Juan Carlos Gardón, Katy Satué, Biotechnologies Applied to Animal Reproduction, 2020
Lydia Gil Huerta, Cristina Álvarez, Victoria Luño Lázaro
Cryopreservation is the only viable method for sperm storage during indefinite periods of time (Gibb and Aitken, 2016). However, freezing-thawing process produces several detrimental effects on the gametes such us loss on sperm viability and motility due to membrane damage caused by the production of ROS, interruption of the membrane functionality as result of separation of lipid bilayers, changes in water transport properties, and alteration in calcium channels (Hammerstedt et al., 1990; Kodoma et al., 1996; Watson, 2000). It also causes damage to the cytoskeleton, in the flagellum, in the acrosome with reduction of the acrosomal integrity, modifications in the head and in the subacrosomal space, in the DNA status, in the genes essential for fertilization and in normal embryonic development (Amann and Pickett, 1987; Valcarce et al., 2013). As a result of these alterations and modifications on sperm, the response to osmotic stress changes and the survival life in the female genital tract might reduce (Flesch and Gadella, 2000). The osmotic stress is due to the extracellular ice crystals development during the cooling process that produces a great increase in the osmolarity of the remaining liquids surround or inside the sperm (Amann and Pickett, 1987).
Autofluorescence as a Parameter to Study Pharmaceutical Materials
Published in Victoria Vladimirovna Roshchina, Fluorescence of Living Plant Cells for Phytomedicine Preparations, 2020
Victoria Vladimirovna Roshchina
Salinity is a major abiotic stress limiting the growth and productivity of plants in many areas of the world due to the increasing use of poor-quality water for irrigation and soil salinization (Gupta and Huang 2014). The typical definition of a halophyte is a plant species that can survive and reproduce under growth conditions with more than 200 mM NaCl. It has been conservatively estimated that there is approximately 1000 million ha of salt-affected land throughout the world (Liu et al. 2018). Salt stress is a combination of ionic stress due to the chaotropic effects of incoming Na+ and Cl– and osmotic stress resulting from a decrease in water potential (Lugan et al. 2010). The result of these disturbances in water management is a loss of turgor, inhibition of cell elongation, stomatal closure, and decrease in the intensity of photosynthesis (Cassaniti et al. 2012). Therefore, it is important to carry out studies that allow the selection of suitable, salt-tolerant species. Some medicinal plants have the ability to grow under salinity due to the presence of different mechanisms for salt tolerance; such plants are known as salt-resisting plants, salt-tolerating plants, or halophytes (Aslam et al. 2011).
Osmotic demyelination syndrome in patients with non-Hodgkin lymphoma: a case report and literature review
Published in International Journal of Neuroscience, 2023
Miguel García-Grimshaw, Amado Jiménez-Ruiz, José Luis Ruiz-Sandoval, Carlos Cantú-Brito, Erwin Chiquete
The first recognized risk factor for the development of ODS was the overly rapid correction of serum sodium concentration in patients with hyponatremia. Later, ODS was also described in patients without hyponatremia or rapid sodium correction. Subsequently, it was found that other organic and inorganic osmolytes can also be involved in ODS pathogenesis [2, 3]. Nowadays, complete pathophysiological mechanisms have not been fully elucidated [2, 6]. This syndrome has a variable clinical presentation, and the routine use of magnetic resonance imaging (MRI) has increased the recognition of mild and even asymptomatic cases [3, 4]. ODS usually affects patients with underlying systemic conditions that impose susceptibility to osmotic stress. Associations with multiple metabolic, infectious, toxic, and psychiatric disorders have been made [2, 3]. Description of ODS in patients with hematological malignancies is limited to a few case reports [7–14]. Here we describe a patient with diffuse large B-cell lymphoma (DLBCL) who suffered clinically mild CPM. Our case was summarized together with other ODS cases complicating non-Hodgkin lymphoma (NHL) patients.
Absorbance and Light Scattering of Lenses Organ Cultured with Glucose
Published in Current Eye Research, 2018
Ali Hendi Sahmi Alghamdi, Hasabelrasoul Mohamed, Samiyyah M. Sledge, Douglas Borchman
Cataract is among the major causes of visual impairment and blindness worldwide.1 Age and diabetes are major factors related to cataract and diabetics are two times more likely to have cataracts than non-diabetics.2 Determining the etiology of diabetic cataracts could facilitate the development of a therapy to delay the onset of cataract. Hyperglycemia is the initiating factor for diabetic cataract.3 The etiology of diabetic cataract is multifactorial, complex, and not completely established. It is likely to involve osmotic stress and/or oxidation related metabolic changes.3,4 Lens organ culture is useful for testing the direct effect of moieties such as cations, glucose, oxygen, antioxidants, or drugs on lens opacity.5,6 Rat lenses were cultured for 5 days in a medium containing a high concentration of glucose that caused the lenses to become opaque.4 Ginkgo biloba extract prevented the opacity from occurring.4 Until a recent study,6 all of the lens organ culture studies usually measured metabolic changes over time and did not directly measure lens opacity by the attenuation of light through the lens.
Taurine prevents ultraviolet B induced apoptosis in retinal ganglion cells
Published in Cutaneous and Ocular Toxicology, 2018
Taurine, betaine, and myoinositol are usually considered as organic osmolyte members in retina3. The taurine transporter (TAUT), betaine/GABA transporter (BGT-1), and sodium/myoinositol cotransporter (SMIT) in the cell membrane are in charge of osmolyte transport outside and inside of the cell4. These transport proteins and the corresponding osmolytes exist extensively in various tissues and organs including retina, lens, kidney, liver and brain, etc. It is the common law that hyperosmotic stress induces osmolytes influx into the cell and hypo osmotic stress induces osmolytes outflux from the cell. The osmotic stress can induce cell shrinkage and increase intracellular ionic strength. The cells resist hyperosmotic stress induced cell damage by osmolytes mobilization as the counterplan5. In virtue of the character of no charge, osmolytes can serve the resistance to intracellular overload of charged ions, the maintenance of intracellular biological function of macromolecule protein and the protection of the DNA breakage6.