Stresses response

Other stressing treatments employed to improve the microbial stability of some meat products merit consideration. This is the case for high hydrostatic pressure (HHP) treatment in use in several countries for the preservation of various sausage or dry-cured ham. By a proteomic investigation, it was notably shown that Lact. sakei can react differently from other bacterial species after an HHP treatment (Jofre et al. 2007). In addition, flow cytometry was successfully used to test the ability of Lact. sakei cells to survive different stresses like acidic or high temperature stresses (Bonomo et al. 2013) illustrating one of the numerous tools available for starter culture selection. 

Finally, from the most recent results obtained on Lact. sake one should keep in mind that  

All this should help further screening of new starter cultures. However, an additional feature not to be forgotten is to investigate these important functions within the complex microhial community that is present, together with Lact. sakei, in the meat ecosystem. 

Dufour, E., Zagorec, M., et al. (2005) Characterization and selection of Lactobacillus sakei strains isolated from traditional dry-sausage. Food Microbiol 22, 529-538. 

Anba-Mondoloni, J., Chaillou, S., Zagorec, M., and Champomier-Verges, M.C. (2013) Catabolism of N-acetylneu-raminic acid, a fitness function of the food-borne lactic acid bacterium Lactobacillus sakei, involves two newly characterized proteins. Appl Environ Microbiol 79, 2012-2018. 

At all levels of the HPA axis, feedback mechanisms exist that control the output of neuropeptides and circulating hormones. These mechanisms regulate the levels of these factors during normal diurnal cycles, but also act to Umit the magnitude of the stress response and terminate its effects. These feedback mechanisms consist of both short loops, where each factor acts to inhibit its own secretion, and long loops, whereby ACTH acts on PVN neurons to inhibit the secretion of CRH, and cortisol acts on the PVN and the pituitary to inhibit the secretion of CRH and ACTH, respectively (de Kloet et al., 1990 de Kloet, 2003). 

It is important to distinguish between the response of the HPA axis to acute stressors, and the response to chronic stress. While the HPA response to acute stressors can clearly be seen as an adaptive response that serves to maintain or re-establish homeostasis, the response to chronic stress can lead to maladaptive conditions, especially in vulnerable individuals, that may initiate or facilitate CNS disease processes, as discussed below. 

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Steroid Hormones and Neurosteroids. Steroids (qv) can affect neuroendocrine function, stress responses, and behavioral sexual dimorphism (78,79) (see Steroids). Mineralocorticoid, glucocorticoid, androgen, estrogen, and progesterone receptors are localized in the brain and spinal cord. In addition to genomic actions, the neurosteroid can act more acutely to modulate the actions of other receptors or ion channels (80). Pregnenolone [145-13-17, ( ) dehydroepiandosterone [53-43-0] C H2 02 (319) are excitatory neurosteroids found in rat brain, independent of adrenal... 

The transverse (circumferential) crack path reveals that the stresses responsible for SCC were axially oriented that is, the tube was pulled at its ends. Residual tube-forming stresses may also have contributed in this case. The specific cracking agent was caustic, which was apparently concentrated by evaporation when water flashed to steam in these locations. 

The cyclic stresses responsible for this failure were apparently bending stresses associated with cyclic thermal expansion and contraction. 

Stress response (Immune system) Osmoregulation Metabolism... 

G proteins are molecular amplifiers for a large number of seven-trans-membrane helix receptors that regulate responses like vision, smell and stress response. They are heterotrimeric molecules, Gap, that dissociate into membrane-bound Ga and Gpy signal transmitters upon activation of the receptor. 

The most characteristic features of viscoelastic materials are that they exhibit a time dependent strain response to a constant stress (creep) and a time dependent stress response to a constant strain (relaxation). In addition when the... 

The term nonlinear in nonlinear programming does not refer to a material or geometric nonlinearity but instead refers to the nonlinearity in the mathematical optimization problem itself. The first step in the optimization process involves answering questions such as what is the buckling response, what is the vibration response, what is the deflection response, and what is the stress response Requirements usually exist for every one of those response variables. Putting those response characteristics and constraints together leads to an equation set that is inherently nonlinear, irrespective of whether the material properties themselves are linear or nonlinear, and that nonlinear equation set is where the term nonlinear programming comes from. 

The anthrax toxin is a tripartite toxin and consists ofthe binding component protective antigen (PA), the lethal factor (LF), which is a metalloprotease, and the edema factor (EF), which is a calmodulin-dependent adenylyl-cyclase. Both enzyme components are translocated via PA into target cells. PA is activated by furin-induced cleavage and forms heptamers, which are similar to the binding components of C2 toxin and iota toxin. In the low pH compartment of endosomes, the heptamers form pores to allow translocation of LF and EF. LF cleaves six of the seven MEKs (MAPK-kinases) thereby inhibiting these enzymes. The functional consequence is the blockade of the MAPK pathways that control cell proliferation, differentiation, inflammation, stress response, and survival. Whether this is the reason for the LT-induced cell death of macrophages is not clear [1]. 

A principle glucocorticoid produced in the zona glometulosa of the adrenal cortex. It is involved in modulating stress responses, immune reactions and food metabolism. 

Very large Serine/Threonine kinases and the molecular Target of Rapamycin, a naturally occurring secondary metabolite, TOR proteins function within multiprotein complexes to couple cell growth and stress responses to environmental and developmental cues. 

TORC1 Regnlates Cell Growth and Stress Responses... 

Proteasomal inhibition represents a novel strategy in cancer treatment and the small molecule Bortezomid (PS-341, Velcade ) has been approved for the treatment of refractory and relapsed multiple myeloma, a proliferative disease of plasma cells. Bortezomid inhibits an active site in a proteasome subunit and remarkably shows selective cytotoxicity to cancer cells. Although the underlying mechanisms are not completely understood bortezomid apparently induces a cell stress response in these tumor cells followed by caspase-dependent apoptosis. Whether bortezomid is beneficial for the treatment of other proliferative disease is currently being tested in clinical trials. 

The human HS cycle can be considered broadly as a period which leads to the dramatic shift in activities of the transcriptional and translational machinery followed by eventual recovery and resumption of original activities preceding stress. Figure 1 depicts many of the key events in the HS cycle for a typical human cell line such as cervical carcinoma-derived HeLa cells. Most cells respond in an identical fashion, but some cell types that have distinctive HS responses. These differences are manifested by shifts in the relative concentrations of accumulated HS proteins and possibly in the pattern of posttranslational modifications. In all cases, however, the cellular stress response is heralded by induction of a specific transcription factor whose DNA binding activity facilitates increased expression of one or more of the stress-inducible genes. 

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