Leeches, extracts

In several experiments, intraperitoneal injections of leech extracts or of another hyaluronidase were found to lessen the susceptibility to hemolytic streptococci intraperitoneally administered. Therefore, it was suggested that hyaluronate in the streptococcal capsules protects the organisms and is responsible for their greater virulence. These results were not confirmed in a similar experiment by McClean. Subsequently, McClean injected a hyaluronidase into mice infected with streptococci and found that the bacterial capsules were initially removed but returned after about one and a half hours. Similarly, Kass and Seastone found that hyaluronidase injections had no effect on the virulence of pneumococci in mice. ... 

Va.t, or Agitated Leeching. Vat or agitated leaching usually extracts copper from oxide or mixed oxysulfide ores containing more... 

Hirudin Antithrombotic 65 Extraction from leeches, recombinant... 

Garter snakes respond to prey extracts with tongue flicking and attempts to bite (Gove and Burkhardt 1975). Test extracts of different prey animals such as earthworms, slugs, crickets, or leeches. Dip cotton balls or Q-tips into extracts and present to captive snakes. Experimenter should be behind screen to minimize snake s responses to light or movement. 

The Leech Book of Bald (ca. AD 950), a herbalist who lived in the time of Alfred the Great, contains a wealth of plant lore that includes ointments to protect against the elfin race and nocturnal visitors , but also mentions an extract of the wild chervil (probably Myrrhis odorata) as a salve for the treatment of tumours. This plant produces a number of chemicals known as lig-nans, which are related in structure to podophyllotoxin, although much better sources of these cytotoxic lignans are the Himalayan plant Podophyllum... 

CAS 90045-73-1 EINECS/ELINCS 289-937-6 Definition Extract obtained from leeches Uses Biological additive in cosmetics... 

Wu N, Zhu Y, Brown S, Oakeshott J, Peat TS, Surjadi R, Easton C, Leech PW, Sexton BA (2009) A PMMA microfluidic droplet platform for in vitro protein expression using crude E. coli S30 extract. Lab Chip 9 3391-3398... 

A recent example in this direction was demonstrated by Ditto and coworkers with the so-called leech-ulator, in which two leech neurons were used for a simple mathematical addition [35]. Leech neurons are used because they have been extensively studied and are well understood. The neurons are electrically stimulated by inserted microelectrodes. Each neuron has its own electrical activity and responds in its own vray to the electrical stimulus. These features can be used to make each neuron represent a number. Calculations are then performed by linking up the individual neurons. Using principles of chaos theory, the two neurons are selectively stimulated. From the signal cascade that follows, the PC can extract the correct answer to a simple addition problem. 

One physiological inhibitor of clotting is heparin, w hich is formed in mast cells. Heparin acts at different steps in the complicated process First, it inhibits the formation of plasma thrombokinase second, the activation of prothrombin third, the enzymic activity of thrombin. Many animal poisons (e.g. the blood poison, hirudin, extracted from leeches) also inhibit blood clotting. In vitro, clotting is prevented commonly by binding Ca++ ions (precipitation with fluoride or oxalate complex formation with citrate, etc.). 

Hirudin is produced by the medicinal leech and may be extracted from its saliva. It is a 65 amino acid peptide. It is now expressed recombinantly in yeast cells and the recombinant product is almost identical to the naturally occurring protein. It acts directly on thrombin, binding to the active site of thrombin, and preventing the enzymatic cleavage of fibrinogen. It will bind both to free thrombin and to thrombin involved in complexes with fibrinogen. It has the advantage that it does not have the same side effect profile as heparin and thus can be used in heparin-intolerant patients. Bivalimdin is low MW (2180) synthetic peptide which mimics hirudin and binds to thrombin at the same site. 

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