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The many aspects of
chemistry compose our lives:
When I think of Chemistry, I usually think of Music
and My Man, however my experience has
forced me to become ultra-chemically conscious in all aspects.
I have posted immediately below information on
acetylcholinestrace inhibitors because I was in a neighborhood caught in the
drift and many people simply thought they had the flu.
If ever you've been exposed to common pesticides
containing acetylcholinestrace inhibitors such as Dursban,
Malathion
and numerous others, this information is vital to you. You, consist of most, if
not all, Americans. If you've ever gotten a prescription
for head lice, your situation is compounded. It may help you explain many of
your migraines and other health problems.
The cholinesterase enzyme reaction
Cholinesterase, which is an enzyme, breaks acetylcholine
down into choline and acetate. It also breaks down succinyl choline, a
neuromuscular blocking agent which is widely used for producing brief paralysis
during surgery. The enzyme is congenitally absent in rare cases. Such people
undergoing surgery may be paralysed for unusually long periods after the usual
dose of succinyl choline. Cholinesterase is required for normal nervous
function. Impulses proceed from one nerve to another, or from a nerve cell to an
effector organ or gland (e.g. a muscle or gland), by a process of chemical
transmission. In this case, when an impulse reaches the end of an axon, it
causes the release of a chemical which is stored in the fine branches at the end
of the axon. The chemical enters the gap between the axon and the nerve cell,
muscle or gland. When it becomes attached, it fires off another nerve impulse or
it makes the effector operate. As soon as this happens, the chemical (namely,
acetylcholine) is destroyed by cholinesterase. This allows the muscle membrane
or nerve to return to its resting state, ready for another nerve impulse if need
be. (1).
Types of cholinesterase
There are two types of cholinesterase enzymes present in
the blood: 1. Acetylcholinesterase (E.C.2.4.2.7) is found mainly in the
erythrocytes. The red blood cell acetylcholinesterase is of the same type as
that present at nerve junctions, and hence has been allocated the same enzyme
number by the Enzyme Commission. This enzyme is also referred to as the true
cholinesterase or red blood cell (RBC) cholinesterase .
2. Butarylcholinesterase (E.C.2.4.2.8) is found in the serum or plasma. This
enzyme is also referred to as pseudocholinesterase, plasma cholinesterase serum
cholinesterase.
Both acetylcholinesterase and butarylcholinesterase are
inactivated by the organophosphate and carbamate groups of pesticides. Certain
individual pesticides are known, however, to inhibit one or other of the enzymes
only partially. For purposes of simplicity, acetylcholinesterase (EC 2.4.2.7)
will be referred to as RBC cholinesterase and butarylcholinesterase (EC 2.4.2.8)
as plasma cholinesterase in this paper.
Regeneration of cholinesterase levels: Once a given
molecule of cholinesterase has been inhibited irreversibly, the only way of
replacing the activity is through synthesis of new enzyme. The synthesis does
not occur in circulating red cell corpuscles, and the only way RBC
cholinesterase is renewed in the blood is through synthesis of the enzyme in
erythropoietic cells of the bone marrow and its subsequent entry into the
circulating blood. Plasma cholinesterase is synthesized in the liver (1). Plasma
cholinesterase is completely regenerated in 50 days, while RBC cholinesterase
regenerates more slowly, at a rate of 1% or less per day (2). The erythrocytes
have a long life (about 120 days), and hence the blood levels recover slowly.
1. Heath DF. Organophosphorus poisons:
Anticholinesterases and related compounds. International series of monographs on
pure and applied biology. Pergamon Press, New York. 1961;13:8.
2. Gage (1967), Tafuri, Roberts (1987) referred to by RG Ames et al. J Soc Occup
Med 1989;39:85-9.
http://www.occuphealth.fi/e/info/anl/195/rama.htm
Transmission Boosting: Anti-Acetylcholinesterase
Agents
Biomonitoring
of exposure to chemicals Guideline for specimen collection
Chemical Awareness is a newsletter and an NGO campaign to move the
chemicals policy in the EU towards better control of harmful chemicals
andimplementation of the precautionary principle in common rules and regulations
of the EU.
http://www.chemical-awareness.com/
Chemical Awareness in Schools
Chemical Awareness in Schools is a
non-profit community network, aiming to raise awareness of hazardous chemicals
in children's environments, and provide information about safer alternatives to
a range of commonly used chemical-based products.
http://www4.tpgi.com.au/users/rdi/cas/
Alliance for Chemical
Awareness (ACA) www.chemicalawareness.org
A
tutorial on balancing chemical equations
Gas
law
Virtual
Lab: Ideal Gas Law
Wilton High
Chemistry
Chemical
Hazardous Substance Tool Kit
BRAIN/CNS 1 Chambers JE, Carr RL. INHIBITION PATTERNS OF BRAIN
ACETYLCHOLINESTERASE AND HEPATIC AND PLASMA ALIESTERASES FOLLOWING EXPOSURES TO
THREE PHOSPHOROTHIONATE INSECTICIDES AND THEIR OXONS IN RATS. Fundam Appl
Toxicol 1993;21(1):111-119. Rats were administered high sublethal
intraperitoneal dosages of the phosphorothionate insecticides parathion, methyl
parathion, and chlorpyrifos, and their oxons. Acetylcholinesterase activities in
cerebral cortex and medulla oblongata and aliesterase activities in liver and
plasma were monitored at 2 hr and 1, 2, and 4 days after exposure. The maximal
inhibition of brain acetylcholinesterase activity was not immediate with
parathion and chlorpyrifos, reflecting the time required for bioactivation of
the phosphorothionates as well as the effectiveness of the aliesterases to
inactivate much of the hepatically generated oxons. In contrast, brain
acetylcholineasterase activities were more quickly inhibited following
administration of paraxon and chlorpyrifos-oxon, which do not require
bioactivation. Brain acetylcholinesterase was also rapidly inhibited following
administration of methyl parathion and methyl paraoxon, reflecting the low
sensitivity of the aliesterases to methyl paraoxon. Aliesterases were inhibited
to a greater extent than acetylcholinesterase at each sampling time with
parathion and chlorpyrifos and their oxons, whereas the reverse was true with
methyl parathion and methyl paraoxon. All of the above patterns correlate with
the in vitro sensitivities of acetylcholinesterase and aliesterases to the oxons.
The very prolonged inhibition of esterase activities following chlorpyrifos
treatment probably results from its substantially greater lipophilicity compared
to the other compounds, which would allow it to be stored and released for
gradual bioactivation. The data reported indicate that the disposition and
effects of different phosphorothionate insecticdes will be influenced by the
sensitivities of target and nontarget esterases for their oxons and by their
lipophilicity, and that predictions of in vivo responses can be made from in
vitro data.
http://sis.nlm.nih.gov
http://ipmworld.umn.edu/chapters/ware.htm
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EnvironMental
Protection
Breast Milk
There are those that believe the greatest source of exposure to
organochlorines that contaminate breast milk are old carpets.
BMMPs
Breast Milk Monitoring Programs (BMMPs): World-Wide Early Warning
System for Polyhalogenated POPs and for Targeting Studies in Children's
Environmental Health
DDT,
Other Pesticides Found in Breast Milk
HUMAN
BREAST MILK IS CONTAMINATED
Drugs
and Toxic Chemicals in Breast Milk
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