Contact activity

Cation A positively charged particle or ion. Channeling Cleavage and furrowing of the bed due to faulty operational procedure, in which the solution being treated follows the path of least resistance, runs through these furrows, and fails to contact active groups in other parts of the bed. 

Table 1. Physiochemical properties of proteins of the contact activation cascade... 

Kerbiriou D, Griffin J Human high molecular 27 weight kininogen. Studies of structure-function relationships and of proteolysis of the molecule occurring during contact activation of plasma. J Biol Chem 1979 245 12020-12027. 

Reddigari S, Kaplan AP Cleavage of human high-molecular-weight kininogen by purified kaUikreins and upon contact activation of plasma. Blood 1988 71 1334-1340. 

Cochrane CG. Revak SD Dissemination of contact activation in plasma by plasma kallikrein. J Exp Med 1980 152 608-619. 

Motta G, Rojkjser R, Hasan AA, Cines DB, Schmaier AH High molecular weight kininogen regulates prekallikrein assembly and activation on endothe- 57 lial cells a novel mechanism for contact activation. 

Schmaier AH Contact activation a revision. Thromb Haemost 1997 78 101-107. 

Inhibitors that block the protease activity of F-XIIa and kallikrein. Plasma contains two protease inhibitors that regulate contact activation Cl inhibitor (Cl-Inh) and a2-macroglobulin (a2-M). 

C23. Colman, R. W., and Schmaier, A. H., The contact activation system Biochemistry and interactions of these surface-mediated defense reactions. Crit. Rev. Oncol. Hematol. 5,57-85 (1986). 

Smoothness of the endothelial lining prevents contact activation of the intrinsic mechanism. 

Contact activation, 4 86-87 Contact adhesives, phenolic resins in, 13 783-784... 

Many insects lay their eggs on the crop towards the top of the plant and the egg hatches with the neonate larva eating its way out of the shell. In many cases the larva then penetrates the crop and will not come into contact with the insecticides sprayed onto the surface of the crop. If, however, it has to walk over a treated area then it will pick up a dose of the compound and, if it is contact active, it will succumb. In addition, if a compound is stomach active the insect must feed to acquire a toxic dose and in feeding it will damage the crop. This is very important for high value fruit and vegetable crops. 

Kinins. These hormones are small peptides that induce contraction of smooth muscles, lower blood pressure (Box 22-D), and increase vascular permeability.176 They also have a function in contact-activated blood coagulation. The most important human kinins are the nonapeptide bradykinin177178 and the related decapeptide lysine-bradykinin (Table 30-4). Other forms such as Met-Lys-bradykinin and Ile-Ser-bradykinin (T-kinin) are also known. The precursors to the kinins, the kininogens,176 are cleaved by the protease kallikrein (Fig. 12-17) or by kallikreinlike enzymes to form the kinins. Kinins are suspected of being important producers of pain in inflammatory conditions such as arthritis.1763... 

There are three potential solutions for annual and perennial weed problems with drip irrigation. One is the use of preemergence herbicides that have residual weed control properties, particularly under continuous moisture. Another is the use of contact herbicides on the emerged weeds in the wet spot or persistent herbicides with contact activity. A third approach is the use of herbicides through the drip system when allowed by the product label (i.e., the use of herbicides capable of killing weeds as they germinate). With all three approaches it is essential that perennial weeds... 

Mirex was first synthesized in 1946 but it was not introduced as a pesticide against hymenopterous insects, especially ants, until 1959 (Smith, 1991). Technical grade mirex consists of approximately 95% mirex and less than 2.5% chlordecone, mostly kepone (Eisler, 1985). Mirex is a stomach insecticide with little contact activity. The main use of mirex was against the imported fire ants in the south-eastern United States (WHO, 1984b). It has also been used to control leaf cutters in South America, harvester termites in South Africa, Western harvester ants in the United States, the pineapple mealy bug in Hawaii and it was proposed to have been used against yellow jacket wasps in the United States (WHO, 1995). Under the trade name of Dechlorane, mirex was used as a fire retardant in electronic components, fabrics, rubber, plastics and electrical goods (Eisler, 1985 WHO, 1995). 

Pixley FLA, De La Cadena R, Rage J D, et al. The contact system contributes to hypotension but not disseminated intravascular coagulation in lethal bacteremia in vivo use of a monoclonal anti-factor XII antibody to block contact activation in baboons. J Clin Invest 1993 92 61-68. 

Abstract In this review, the general principles of antimicrobial surfaces will be discussed in detail. Because many common products that keep microbes off surfaces have been banned in the past decade, the search for alternatives is in full run. In recent research, numerous new ways to produce so-called self-sterilizing surfaces have been introduced. These technologies are discussed with respect to their mechanism, particularly focusing on the distinction between biocide-releasing and non-releasing contact-active systems. New developments in the catalytic formation of biocides and their advantages and limitations are also covered. The combination of several mechanisms in one surface modification has considerable benefits, and will be discussed. 

Keywords Antibacterial Antimicrobial Bacteria Biocide Contact-active Light-activated Photocatalytic Release Self-polishing Surface... 

Another way to measure the efficiency of a biocidal surface is by detection of the ATP bioluminescence of the adhering microbial cells [18], With this elaborate method, the killing rate of a surface can be measured and it is possible to distinguish between growth inhibition and killing. However, the method does not distinguish between release and contact activity. In general, there is no test that can clearly tell the difference between a contact-active and a release system. 

---