Noxious factors

Once acdvated, microglia can produce noxious factors including pro-inflammatory cytokines, chemokines, quinolinic acid, arachidonic acid and its metabolites, and excitatory amino acids among others. A major defense mechanism provided by MP is the producdon of free radicals and reacdve molecular... 

The heterogeneous group of cataract models can be divided into subgroups according to the origin of the noxious factors involved, i.e. internal versus external triggers (Wegener and Hockwin, 1987). 

All aqueous extracts are brown colored, and so is the Hillsborough River where samples of hydrilla are found. Examination of Table II, however, suggests that the location of the second peak in this water sample is significantly different from the other five samples. Presently, chromatograms of natural waters and the distribution of hydrilla are being obtained and compared with a view to being able to understand those factors that may limit the growth and spread of this noxious aquatic plant. 

The most common etiology is exposure to environmental tobacco smoke, but other chronic inhalational exposures can also lead to COPD. Inhalation of noxious particles and gases stimulates the activation of neutrophils, macrophages, and CD8+ lymphocytes, which release a variety of chemical mediators, including tumor necrosis factor-a, interleukin-8, and leukotriene B4. These inflammatory cells and mediators lead to widespread destructive changes in the airways, pulmonary vasculature, and lung parenchyma. 

A one-page essay in which it is suggested that evolution in plankton is driven by a watery arms race has attracted much attention (Smetacek 2001). Smetacek discusses the concept that defence of phytoplankton by mechanical protection, increased cell size, formation of spines, or production of noxious chemicals leads to the adaptation of zooplankton to these measures. This process resulted in the shape and properties of phyto- and zooplankton that we observe today. In the years following that essay several candidate molecules were discovered and intensely studied. The concept that chemical signals and defence metabolites are important factors in plankton ecology has now become widely accepted. 

The nature of the amino acids is an important factor in the choice of a solvent and different solvents will permit better resolution of acidic, basic or neutral components (Table 10.7). In general, increasing the proportion of water in the solvent will increase all RF values and the introduction of small amounts of ammonia will increase the RF of the basic amino acids. Some solvents contain noxious chemicals, e.g. phenol, and this may restrict their routine use. The chemical composition may also limit the range of locating reagents which can be satisfactorily applied. For example, sulphanilic acid reagent cannot be used with phenolic solvents. 

Homologs of VR1 with a high threshold (> 52°C) for activation by noxious heat, or sensitivity to membrane stretch, provisionally termed vanilloid receptor-like protein (VRL-1) (Caterina et al., 1999) and stretch-inactivated channel (SIC) (Suzuki et al., 1999), respectively, have been identified. Neither channel is activated by vanilloid agonists (Caterina et al., 1999 Suzuki et al., 1999). A mouse ortholog of VRL-1 acts as a growth factor regulated channel (GRC) permeable to Ca2+ ions (Kanzaki et al., 1999). A splice variant of VR1 (VR.5 sv) that lacks the majority of the intracellular N-terminal domain is refractory to activation by vanilloid agonists, protons or noxious... 

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