To whoever still following this mercury topic, it is especially important for parents, future mums and dads, as well as guardians raising babies, the young loved ones. You may find some of the effects of mercury for pregnant mums and young infants to be shocking, but it is better to know it now, then late or never.
Let's start. The development of the brain is a marvelous even that has, as yet, defied our ability to completely understand this God given phonomenon. But, we do know many intriguing things about this process. Basically, the brain must be constructed from a mere three layers of cells that differentiate into numerous types of specialized cells which in turn sprout out into trillions of processes, each moulded into incredible exactness. During this process, the brain makes far too many connections and must remove a large number of them by a process called pruning, just as you would prune a fruit tree. This pruning process is extremely precise and requires a critically timed release of higher concentrations of glutamate. Too much glumate for too long a time and the brain will be overpruned, too little, and the connections will form a mass of confusing signals.
As this delicate moulding process takes place, special enzymes make their appearance in the brain, again in a specifically timed sequence. Mercury, as an enzyme poison, inteferes with this process, causing the brain to be 'miswired'. The process of miswiring can result in anything from mild behavioral and learning problems to major disorders such as autism and other forms of cerebral malfunction. Another way mercury seems to interfere with this process is by altering the careful balance of calcium within the cell.
As you would have realized by now, one of the central processes in brain injuries and degeneration is the formation of free radicals. For example, in Down's syndrome there is a fourfold increase in these destructive particles. One of the ways mercury induces free radical formation is by damaging a cell's mitochondria. Because of this loss of energy producing capacity, the neuron becomes infinitely more susceptible to excitotoxicity injury and death even in the presence of normal levels of the neurotransmitter, glutamate. The cycle continues until the cells begin to die or the dendritic fibers shrink. It is these dendritic fibers that make the trillions of connections in the brain.
Destructions of the dendrites can occur independant of the death of the neuron. This is especially important when considering chronic exposure to very low concentrations of mercury. By removing the mercury and supplying nutrients to the neuron, we may be able to regrow these dendritic spines that are so critical to brain function.
Neurotransmitters, like most other things in the brain, appear in a a set pattern, a sequence which is carefully controlled during brain development but can be disrupted by environmental toxins such as mercury. For example, mercury has been shown to cause a sudden release of acetylcholine in the brain, which can not only interrupt development signals but can be directly neurotoxic.
Medical science generally assumes a substance is safe if it does not cause an obvious abnormality on neurological function or behavior. For example, if a substance does not cause a seizure or loss of movement, it is considered generally safe. Unfortunately, this is very naive and dangerous thinking. The human brain is a very complex structure that can withstand significant injuries with only subtle changes in function, yet even these subtle effects can have a devastating impact on our children's ability to function normally throughout life.
But of special concern is mercury's ability to do two things in the brain. One, it activate the brain's immune system microglia, and another is to poison the glutamate re-uptake system. The amino acid glutamate, is used by the brain as a neurotransmitter, mainly to cause excitation of special brain cells, used for communication between neurons. But, overexciting the brain can be very dangerous, it can lead to seizures, and destruction of brain cells by a process called excitotoxicity.
Mercury is unique among metals in that it can selectively block the glutamate re-uptake system, even when present in incredible small concentrations. When the system is blocked, free glutamate accumulates in the brain's extracellular spaces, triggering excitotoxicity. The glutamate transporter continues to be impaired since mercury stays in the brain for such a long periods of time.
The infant brain is four times more sensitive than the adult brain to excitotoxicity. This is because many of the infant brain's protective systems are inmature and poorly developed. Introduction of mercury during this delicate process can cause glutamate levels to rise too soon or accumulate in high concentrations, resulting in miswiring of the brain. The effects of this miswiring can be subtle or devastating, depending on many conditions, the dose of the mercury, when it was given, and the nutritional status of the body.
Subtle changes may result in minor behavioral problems, such as difficulty with memory and cognition, or a loss of anger control. As a child, these conditions may be classed as attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), or one of autism spectrum disorders. In more severe cases, the damage may result in full blown autism or Asperger's syndrome. So future mums and dads, and present parents, do take this seriously.
Acute, high does mercury poisoning in adults is characterized by a localization of the toxin in the occipital lobes of the brain, especially in an area called calcarine cortex, which is part of the brain controlling vision. This may explain the loss of color vision and tunnel vision seen in mercury miners.
Significant but lower accumulation of mercury also occur in other parts of the brain. In children who exposed to high dose mercury, widespread destruction of neurons in the brain accompanied by scarring, but more importantly gorss abnormal development of brain cell layers with isolated clumps of malformed brain cells and disorganization of the cells in the cortex of the brain.
Now, let's look briefly below at how mercury damages cells.
- Inhibits enzyme function, such as mitochondrial enzymes, glutathione reductase
and synthease.
- Binds to nucleic acids
- Induces astrocyte swelling
- Inhibits protein synthease
- Inhibits dopamine, seratonin and norepinephrine
- Inhibit cytokine production
- Inhibit glutamate transport proteins
- Increases free radical production
- Encourages lipid peroxidation
- Binds to cell membranes
As I did mentioned before that a close correlation between the number of dental amalgams in a mother's mouth and mercury tissue levels, including brain levels, in her baby. Toxicity to the baby while in the mother's uterus can occur without the mother showing any signs of mercury toxicity.
One obvious question is, if mercury is so toxic to the developing baby, why are any babies born normal? The answer is the same as for adults. Sensitivity to toxicity depends on a number of variables, such as the condition of the antioxidant network, state of general nutrition, presence of natural metal chelators, differences in DNA repair enzymes and biochemical differences as well. Mercury uses a cysteine transport system in the placenta and that neutral amino acids during pregnancy would naturally transfer less mercury to the baby.
How long mercury stays in the body depends on a particular tissue's or organ's ability to flsuh the metal. The half life for the kidney is sixty four days. What this means is for every sixty four day period, half of the mercury in the kidney will be excreted in the urine. For the body as a whole, the half life is fifty four days, and for the brain it is one year.
Check this out. Studies on mercury miners, and those exposed during industrial accidents, indicate that mercury can remain in the brain as long as ten years after a single exposure, but the damage produced by the mercury can last over thirty years! If any of you heard and read about the Minamata exposure, you will know about this incident. Those victims were neurologically impaired when examined after twenty years later.
The form mercury takes in the body can also influence its half life, due to the ways in which the different forms are distributed to bodily systems. The mercury from dental amalgam is inorganic mercury, but it partially converted to methylmercury by bacteria in the mouth. As a result, mercury vapor from dental amalgams is especially toxic to the brain. Once in the brain in its converted state, the mercury half life is suddenly increased.
In next post, I will write about how mercury affect childhood and adults. Stay tuned.
Let's start. The development of the brain is a marvelous even that has, as yet, defied our ability to completely understand this God given phonomenon. But, we do know many intriguing things about this process. Basically, the brain must be constructed from a mere three layers of cells that differentiate into numerous types of specialized cells which in turn sprout out into trillions of processes, each moulded into incredible exactness. During this process, the brain makes far too many connections and must remove a large number of them by a process called pruning, just as you would prune a fruit tree. This pruning process is extremely precise and requires a critically timed release of higher concentrations of glutamate. Too much glumate for too long a time and the brain will be overpruned, too little, and the connections will form a mass of confusing signals.
As this delicate moulding process takes place, special enzymes make their appearance in the brain, again in a specifically timed sequence. Mercury, as an enzyme poison, inteferes with this process, causing the brain to be 'miswired'. The process of miswiring can result in anything from mild behavioral and learning problems to major disorders such as autism and other forms of cerebral malfunction. Another way mercury seems to interfere with this process is by altering the careful balance of calcium within the cell.
As you would have realized by now, one of the central processes in brain injuries and degeneration is the formation of free radicals. For example, in Down's syndrome there is a fourfold increase in these destructive particles. One of the ways mercury induces free radical formation is by damaging a cell's mitochondria. Because of this loss of energy producing capacity, the neuron becomes infinitely more susceptible to excitotoxicity injury and death even in the presence of normal levels of the neurotransmitter, glutamate. The cycle continues until the cells begin to die or the dendritic fibers shrink. It is these dendritic fibers that make the trillions of connections in the brain.
Destructions of the dendrites can occur independant of the death of the neuron. This is especially important when considering chronic exposure to very low concentrations of mercury. By removing the mercury and supplying nutrients to the neuron, we may be able to regrow these dendritic spines that are so critical to brain function.
Neurotransmitters, like most other things in the brain, appear in a a set pattern, a sequence which is carefully controlled during brain development but can be disrupted by environmental toxins such as mercury. For example, mercury has been shown to cause a sudden release of acetylcholine in the brain, which can not only interrupt development signals but can be directly neurotoxic.
Medical science generally assumes a substance is safe if it does not cause an obvious abnormality on neurological function or behavior. For example, if a substance does not cause a seizure or loss of movement, it is considered generally safe. Unfortunately, this is very naive and dangerous thinking. The human brain is a very complex structure that can withstand significant injuries with only subtle changes in function, yet even these subtle effects can have a devastating impact on our children's ability to function normally throughout life.
But of special concern is mercury's ability to do two things in the brain. One, it activate the brain's immune system microglia, and another is to poison the glutamate re-uptake system. The amino acid glutamate, is used by the brain as a neurotransmitter, mainly to cause excitation of special brain cells, used for communication between neurons. But, overexciting the brain can be very dangerous, it can lead to seizures, and destruction of brain cells by a process called excitotoxicity.
Mercury is unique among metals in that it can selectively block the glutamate re-uptake system, even when present in incredible small concentrations. When the system is blocked, free glutamate accumulates in the brain's extracellular spaces, triggering excitotoxicity. The glutamate transporter continues to be impaired since mercury stays in the brain for such a long periods of time.
The infant brain is four times more sensitive than the adult brain to excitotoxicity. This is because many of the infant brain's protective systems are inmature and poorly developed. Introduction of mercury during this delicate process can cause glutamate levels to rise too soon or accumulate in high concentrations, resulting in miswiring of the brain. The effects of this miswiring can be subtle or devastating, depending on many conditions, the dose of the mercury, when it was given, and the nutritional status of the body.
Subtle changes may result in minor behavioral problems, such as difficulty with memory and cognition, or a loss of anger control. As a child, these conditions may be classed as attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), or one of autism spectrum disorders. In more severe cases, the damage may result in full blown autism or Asperger's syndrome. So future mums and dads, and present parents, do take this seriously.
Acute, high does mercury poisoning in adults is characterized by a localization of the toxin in the occipital lobes of the brain, especially in an area called calcarine cortex, which is part of the brain controlling vision. This may explain the loss of color vision and tunnel vision seen in mercury miners.
Significant but lower accumulation of mercury also occur in other parts of the brain. In children who exposed to high dose mercury, widespread destruction of neurons in the brain accompanied by scarring, but more importantly gorss abnormal development of brain cell layers with isolated clumps of malformed brain cells and disorganization of the cells in the cortex of the brain.
Now, let's look briefly below at how mercury damages cells.
- Inhibits enzyme function, such as mitochondrial enzymes, glutathione reductase
and synthease.
- Binds to nucleic acids
- Induces astrocyte swelling
- Inhibits protein synthease
- Inhibits dopamine, seratonin and norepinephrine
- Inhibit cytokine production
- Inhibit glutamate transport proteins
- Increases free radical production
- Encourages lipid peroxidation
- Binds to cell membranes
As I did mentioned before that a close correlation between the number of dental amalgams in a mother's mouth and mercury tissue levels, including brain levels, in her baby. Toxicity to the baby while in the mother's uterus can occur without the mother showing any signs of mercury toxicity.
One obvious question is, if mercury is so toxic to the developing baby, why are any babies born normal? The answer is the same as for adults. Sensitivity to toxicity depends on a number of variables, such as the condition of the antioxidant network, state of general nutrition, presence of natural metal chelators, differences in DNA repair enzymes and biochemical differences as well. Mercury uses a cysteine transport system in the placenta and that neutral amino acids during pregnancy would naturally transfer less mercury to the baby.
How long mercury stays in the body depends on a particular tissue's or organ's ability to flsuh the metal. The half life for the kidney is sixty four days. What this means is for every sixty four day period, half of the mercury in the kidney will be excreted in the urine. For the body as a whole, the half life is fifty four days, and for the brain it is one year.
Check this out. Studies on mercury miners, and those exposed during industrial accidents, indicate that mercury can remain in the brain as long as ten years after a single exposure, but the damage produced by the mercury can last over thirty years! If any of you heard and read about the Minamata exposure, you will know about this incident. Those victims were neurologically impaired when examined after twenty years later.
The form mercury takes in the body can also influence its half life, due to the ways in which the different forms are distributed to bodily systems. The mercury from dental amalgam is inorganic mercury, but it partially converted to methylmercury by bacteria in the mouth. As a result, mercury vapor from dental amalgams is especially toxic to the brain. Once in the brain in its converted state, the mercury half life is suddenly increased.
In next post, I will write about how mercury affect childhood and adults. Stay tuned.
No comments:
Post a Comment