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N U T R I T I O
A S S E S S M E
N A L
N T S
Amino Acids Analysis Urine/Plasma
Overview
What do depression, heart disease, and detoxification impairments all have in common?
The answer lies in their association with amino acid imbalances. Low tyrosine or
phenylalanine can result in abnormal levels of mood-regulating dopamine and
catecholamines. Both low taurine and high homocysteine have been associated with
cardiovascular problems. And low levels of methionine, glycine, and glutathione
(among others) can result in compromised clearance of toxic substances from the
body. Great Smokies’ Amino Acids Analysis is a quick and convenient means of getting to the root of some of these chronic disorders. Our report form provides levels of
over 40 analytes.
Problem areas are targeted, such as dietary inadequacy (or malabsorption) of essential amino acids, insufficiencies of particular vitamins or mineral cofactors required in
amino acid metabolism, and susceptibility toward particular diseases.
Precise results make possible specific nutritional intervention, resulting in improved
clinical outcomes.
Amino acids are essential to life. In free form or linked as peptides they assume
important roles in such activities as neurotransmitter function, pH regulation, cholesterol metabolism, pain control, detoxification, and control of inflammation. Amino
acids comprise the building blocks of the proteins found in structural tissues of the
body. In fact, the word “protein” derives from the Greek “protos,” meaning “first,” a
designation underscoring its prominence.
The various functions supported by amino acids in the body depend upon proper
amino acid metabolism. Metabolic impairments are hidden in many individuals. These
impairments may be expressed as subtle symptoms or overt diseases. Amino acids
analysis should be considered whenever a thorough nutritional and metabolic
workup is desired for an individual. In addition to family history, a variety of conditions
may alert the practitioner to the possibility of disordered amino acid metabolism,
including chronic fatigue, frequent headaches, chronic gastrointestinal distress, intolerances to foods and chemicals, persistent inflammatory responses, depression,
learning disabilities, malnutrition, neurological disorders, or symptoms of degenerative disease.
Proteins and Amino Acids
Molecules composed of several amino acids, up to several dozen, are generally
classified as "peptides." Many "short-chain" peptides of dietary origin are absorbed
intact,1 and they may function in a manner not shared by individual amino acids. Most
are broken down further, via digestive proteolysis, into their component amino acids.
Distinctions between the many different amino acids can be made by examining their
chemical structures.
Every amino acid molecule contains at least one amino group (-NH2) and carboxyl
group (-COOH). Amino acids are in either an “L” or “D” configuration, the difference
determined by which side of the molecule the amino group (-NH2) is attached. All,
with the exception of glycine and taurine, have this asymmetry; taurine carries a
sulfonic acid group instead of a carboxyl group. In natural protein, all amino acid
residues are of the “L” configuration. “D” configurations may be formed by bacteria,
tissue catabolism, or synthetically. Although a small portion of ingested “D” form
amino acids can be “racemized,” or rearranged, to form “L” configurations, most “D”
configured amino acids are unavailable for peptide and protein synthesis and may
even inhibit enzymes. For this reason, D-configured amino acids are not desirable for
nutritional supplementation. An exception in this case might be DL-phenylalanine
(DLPA) which, owing to its ability to inhibit the normal enzymatic degradation of
endorphins and enkephalins, has been used therapeutically for pain management.2
What this test does:
Identifies nutritional deficits,
metabolic impairments, and
amino acid transport disorders.
Turn-around Time 10 days
© 2004 Genova Diagnostics
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P P L I C A T I O N
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Amino Acids Analysis Application Guide
Many amino acids are produced by the body. Others, the essential amino acids,
cannot be endogenously synthesized in adequate amounts, so that they must be
obtained from the diet. The eight essential amino acids in humans are: isoleucine,
leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Semi-essential amino acids are those for which there is some endogenous synthesis,
but not enough for physiological needs. These include arginine, histidine, cysteine,
and taurine (for infants).
The protein amino acids include the eight essential, and twelve others. Two more
amino acids are hydroxylated after they are incorporated into polypeptide or protein
structure: Lysine becomes hydroxylysine, and proline becomes hydroxyproline. This
makes for a total of 22 different amino acids in protein structures.
Still other amino acids, including beta-alanine, citrulline, homocysteine, cystathionine,
ornithine, and alpha-aminoadipic acid, are important because they provide information
on conversion capability in the body or dietary adequacy of the essential amino acids.
Imbalances in any of these amino acids can indicate impairments in metabolism.
Some Important Amino Acids
Synthesis of thyroid hormone
3,5,3-Triiodothyronine (T3)
I
C=O
CH2-CH
NH
HO
I
3,5-Diiodotyrosine
I
HO
I
O
I
I
CH2-CH-COOH
NH2
Thyroxine (T4)
I
HO
I
O
CH2-CH-COOH
I
Triiodothyronine (T3)
© 2004 Genova Diagnostics
NH2
Some amino acids deserve particular mention, owing to their pivotal role in
the body. Examples include methionine, taurine, cysteine, lysine, arginine,
tryptophan, and glutamine.
Methionine is a crucial essential amino acid which brings methyl groups and sulfur
into the body. It is required for the formation of body tissues, metabolism of carbohydrates, lipids and amino acids, and antioxidant and detoxification processes.
Methionine is the essential precursor of the important amino acids cysteine, glutathione, and taurine and, via cysteine, contributes to the formation of insulin and
coenzyme A. Methylation (via S-adenosylmethionine) is essential to genetic expression, muscle metabolism, adrenal catecholamine balance, and formation of choline
and acetylcholine. Methionine metabolism is subject to many impairments, resulting
in a variety of disorders, including cardiovascular disease,3 neural tube defects,4
osteoporosis,5 and neuropsychiatric disorders.6
Taurine, a non-protein metabolite of methionine, has several notable actions in the
body. Acting as an anti-oxidant, taurine scavenges excess hypochlorite ions (OCl¯).
In addition, it serves as a neurotransmitter, conjugates with cholesterol to form a
component of bile, helps regulate the intra-cellular concentrations of magnesium,
calcium, potassium, and sodium, and is magnesium-sparing. Taurine promotes potassium retention by the heart, and it appears to reverse cardiac abnormalities induced
by cardiac glycosides or epinephrine.7 Full-term infants have minimal capacity to
metabolize methionine. Mother’s milk is high in taurine, while cow’s milk contains only
trace amounts. In response to "failure-to-thrive" problems, amino acids were finally
added to baby formula in the 1980s.
Cysteine, a key player in methionine metabolism, forms disulfide linkages in and
between protein chains. It reacts with a derivative of pantothenic acids to form
coenzyme A, serves as a precursor of taurine, and is the rate-limiting component of
the antioxidant and detoxifying tripeptide, glutathione (GSH). In the immune system,
sulfhydryl compounds augment the activation of cytotoxic T cells, T-cell proliferation
in response to mitogens, and the differentiation of T and B lymphocytes. Conjugation
with GSH is a critical step in the detoxification and excretion of most xenobiotics and
metabolically produced oxidizing agents. In acetaminophen toxicity, N-acetylcysteine
protects against hepatotoxicity primarily by serving as a nutritional precursor for GSH
synthesis.8 Total and reduced glutathione concentrations are commonly low in AIDS
patients, and they appear to be a powerful yardstick for predicting survival in HIV
infection.9,10,11 GSH deficiencies have also been documented in a number of pulmonary
diseases, including acute respiratory distress syndrome, asthma, chronic obstructive
pulmonary disease, pulmonary fibrosis, and neonatal lung damage.12
In amino acid metabolism, lysine assists the transfer of amino groups by forming the
linkage between transaminase enzymes, such as SGPT and SGOT, and pyridoxal
phosphate, the coenzyme needed for transamination. Lysine can fulfill this role
because it carries two amino groups; one forms the attachment (peptide bond) to the
transaminase protein and the other helps to anchor the pyridoxal phosphate. Lysine
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Amino Acids Analysis Application Guide
also appears to impact bone health by enhancing intestinal calcium
absorption and improving renal conservation of the absorbed calcium.13 It is also essential for the formation of carnitine and the utilizaDietary Protein
tion of fatty acids for energy by cells14 and is needed for proper
Digestion
immune function. Supplementation with L-lysine has been shown to
Stomach, small intestine
enhance thymus growth and improve immune system parameters.15
Arginine requirements exceed the body’s capacity to synthesize it,
Peptides
thus qualifying it as a semi-essential amino acid. Among arginine’s
Peptidase enzymes
varied properties is its ability to stimulate release of growth hormone
Small intestine
and prolactin, as well as the pancreatic secretion of insulin and
Amino acids
glucagon. Arginine functions as a precursor to nitric oxide, a key
player in processes such as neurotransmission, control of platelet
Absorption into blood stream
aggregation and adhesion, blood pressure regulation, immune systhrough intestinal mucosa
tem cytotoxicity, and relaxation of intestinal smooth muscle.
Administration of arginine has been demonstrated to reduce intimal
urea
thickness and vascular reactivity in atherosclerosis,16 as well as to
Liver functions
cycle
decrease platelet clumping and clot formation within arterial walls.17
Arginine also enhances collagen deposition, demonstrating its role
NH4+
in wound healing and disorders such as gastric ulcer.18
urea
Another of the essential amino acids, tryptophan, serves as the
citric
precursor of the hormone, serotonin, a vasoconstrictor and neuroacid
NADH
cycle
transmitter influencing sleep, appetite, and mood. Studies of
Peripheral
depressed patients have demonstrated reduced levels of tryptophan,
tissue
suggesting in some cases of depression a reduced tryptophan
CO2
synthesis
ATP
availability to the brain.19,20 Serotonin, after methylation by
S-adenosylmethionine,
becomes melatonin, a key regulating
Liver proteins
Enzymes
hormone in the body. Melatonin modulates circadian rhythms in the
Plasma proteins
body and immune and endocrine activity and possesses antioxiDetoxication
Immune factors
dant and oncostatic properties. A dietary lack of tryptophan or
Peptide conjugation
Glutathione conjugation
insufficient S-adenosylmethionine may result in a significant defiMetallothionein
ciency of melatonin.
Sulfation
Glutamine is the most abundant amino acid in the bloodstream, servMethylation
ing as an important vehicle for nitrogen transport. In cells, glutamine
can donate one of its nitrogen atoms as an amide to form nicotinamide
from niacin (vitamin B3), a necessary step in the formation of the very important cofactor
“NAD.” Although considered to be non-essential since it is synthesized by the body, it
may be more aptly described as a "conditionally essential" amino acid—an amino acid
which is non-essential in health, but required in greater amounts during certain physiological states where tissue utilization exceeds the rate of biosynthesis. Glutamine is
important for the maintenance of GI mucosal integrity21; its deficiency is associated with
gut atrophy during stress22; and large doses of glutamine have been shown to prevent
mucosal atrophy and bacterial translocation resulting from various insults, including
methotrexate and radiation injury.23,24,25
Amino Acid Metabolism
Uses of Amino Acids Analysis
© 2004 Genova Diagnostics
Owing to advancements in amino acid measurement, more than 40+ analytes can
now be measured, providing information on a wide spectrum of metabolic and nutritional disorders, including: protein inadequacy, gastrointestinal insufficiencies,
inflammatory responses, vitamin and mineral dysfunctions, detoxification impairments, cardiovascular disease, ammonia toxicity, neurological dysfunction, and
inborn errors of metabolism. Because amino acid measurement was once limited to
the detection of inborn errors of metabolism, such as phenylketonuria (PKU), many
physicians are not aware of the vast amount of clinical information now available to
them through amino acids analysis.
Dietary Protein Adequacy
Since essential amino acids cannot be formed in the body and must be obtained from
the diet, low levels of essential and semi-essential amino acids can indicate dietary
inadequacy. Catabolism of body protein may contribute relatively small amounts of
essential amino acids to blood and urine.
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Amino Acids Analysis Application Guide
Disorders Associated with
Amino Acid Imbalances
Alcoholism
Ammonia toxicity
Ataxia
Behavioral disorders
Cardiovascular disease
Chemical intolerances
Depression
Dermatitis
Detoxification impairments
Excessive inflammation
Hyperlipidemias
Hypertension
Hypotonia
Inflammatory disorders
Insomnia
Mental retardation
Myopathies
Neural tube defects
Ocular disorders
Osteoporosis
Oxidative stress
Poor immunity
Poor wound healing
Rheumatoid arthritis
Seizures
Weak skin and nails
© 2004 Genova Diagnostics
Gastrointestinal Dysfunction
Amino acids analysis can indicate various aspects of gastrointestinal dysfunction.
Measured levels in the urine of the peptides anserine and carnosine can result from
either excess amounts in the diet or deficient peptidase activity in the gut; subnormal
levels of nutritionally essential amino acids, together with increased urine or plasma
levels of these peptides, indicate incomplete digestive proteolysis.26 Altered intestinal
permeability is commonly observed in such individuals. Since histidine is required to
make histamine, the first digestive response in the stomach, low plasma or urine histidine may also suggest maldigestion. Finally, elevated urine hydroxyproline appears to
be a hallmark for celiac disease and other malabsorption states, with the greatest
hydroxyproline excretion occurring in those patients with the most pronounced steatorrhea.27 This is believed to reflect an increased turnover of collagen and may be
related to the osteomalacia sometimes accompanying malabsorption.28
Renal Function
The kidney plays a major role in amino acid metabolism and nutrition; amino acid
reabsorption by renal tubules salvages about 70 g of filtered amino acids per day in a
70 kg man. Comparison of blood and urine amino acid levels and measurement of the
creatinine excretion in a 24-hour urine sample can provide an excellent assessment
of kidney function. High blood levels with low urine levels and a low 24-hour creatinine suggest subnormal renal clearance, while the opposite is seen in abnormally
high renal clearance.
Functional Adequacy of Vitamins and Minerals
Because various vitamins and minerals are needed as cofactors in amino acid
metabolism, abnormal patterns in blood or urine can provide telltale signs of functional deficiency of these nutrients. For example, levels of those amino acids subject to
transamination can point to pyridoxal phosphate (vitamin B6) dysfunction. These
include alpha-aminoadipic acid, alanine, aspartic acid, tyrosine, leucine, isoleucine,
and valine. Similarly, magnesium serves as an enzyme activator in a number of reactions, and certain elevations and deficits can suggest a deficiency. Ethanolamine, for
example, might be elevated, while phosphoethanolamine, downstream from the former, would be depressed. Phosphoserine might be high, and serine, low. Other nutritional cofactors involved in amino acid metabolism include thiamine, riboflavin,
niacin, B12 and folate, zinc, and manganese.
Inflammation
Three amino acids are critical to antioxidant, anti-inflammatory functions: cysteine, glutathione, and taurine. Cysteine is considered to be the rate-limiting factor in the synthesis of the antioxidant tripeptide, glutathione (GSH). Functioning as a reducing agent to
maintain other molecules in the reduced form, GSH is thought to be important during
inflammatory response, influencing the production of phagocytes. A study of healthy
human subjects revealed that persons with healthy intracellular GSH levels had significantly higher numbers of CD4+ T cells than those with reduced GSH levels, and a
reduction in GSH levels to the suboptimal range resulted, on the average, in a 30%
decrease in these T cells. The decrease was prevented by treatment with N-acetylcysteine.29 Decreased concentrations of cysteine have been reported in patients following
severe trauma,30 and lower GSH levels have been associated with malignancy.31
Taurine acts as a specific scavenger for the hypochlorite ion (OCl¯), which is generated in vivo during phagocytosis and oxidant response. The concentration of taurine is
very high in polymorpho-nucleocytes (PMNs) which distribute hydrogen peroxide
during the inflammatory response. Adequate taurine naturally limits the degree of
inflammation and allows formation of stable chloroamines from excess OCl¯. When
taurine is low, the inflammatory response is enhanced and aldehydes may form, commonly resulting in aldehyde sensitivities and oxidative stress reactions, such as the
modification of LDL cholesterol by malondialdehyde.32
Detoxification Impairment
Many amino acids, free or in peptide form, are involved in the body’s detoxification of
endogenous and exogenous compounds. Included in this group are methionine, cysteine, glutathione, glutamine, glycine, alanine, aspartic acid, and taurine. Deficiencies
in any of these can result in impaired Phase II conjugation reactions, an accumulation
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Amino Acids Analysis Application Guide
of potentially toxic intermediates, and subsequent tissue damage. Subnormal blood or
urine levels of these amino acids can imply impaired detoxification functions which
can provoke neurological diseases, chemical intolerances, and chronic fatigue.33
Cardiovascular Disease
Impaired methionine metabolism, particularly the condition known as homocystinuria,
has been found associated with coronary artery disease,34 peripheral and cerebral
occlusive disease,35 myocardial infarction,36,37 and stroke.38 Homocysteine is an intermediate in the catabolism of methionine, and it can either be remethylated into
methionine or broken down into cysteine. When the enzymes involved do not function
properly, homocysteine can accumulate, which then contributes to oxidative damage
of LDL cholesterol and the vascular endothelium. Vitamins B6, B12, folic acid, betaine,
and serine are all essential to methionine catabolism; consequently, deficiencies in
any of these nutrients may aggravate the condition. An oral challenge of L-methionine
(25 mg/kg body weight) during the day of the urine collection is often utilized to rule
out homocystinuria.
Neurological Dysfunction
Amino acids, such as tryptophan, phenylalanine, and methionine, can influence pain
threshold, mood, and sleep patterns. Tryptophan is the precursor of serotonin, which
influences sleep patterns and mood. Phenylalanine converts to the neurotransmitter
tyrosine and to the adrenal catecholamine, norepinephrine (NE), both of which influence mood and behavior. Numerous studies suggest that NE inhibits the release of
adrenocorticotropic hormone (ACTH) by suppressing corticotropic releasing factor
(CRF) secretion in the hypothalamus. Pre-treatment with supplemental tyrosine
appears to prevent the behavioral depression and hypothalamic NE depletion
observed following an acute stress and to suppress the rise in plasma cortisol.39
Tyrosine's impact on mood may be partly related to its function as precursor to the
thyroid hormones thyroxin and triiodothyronine. The analgesic peptides, endorphins
and enkephalins, are composed of amino acids; methionine enkephalin has an analgesic potency 20 times that of morphine. Catecholamines must be methylated by
S-adenosylmethionine (SAM) for proper function; low levels of SAM have been
observed in some cases of depression.40
Ammonia Toxicity
Whenever an amino acid is broken down, nitrogen is released, either as an amino
group (-NH2) or as an ammonium ion (NH3+). Although nitrogen is essential to the
body, an excess can form ammonia which is toxic to brain tissue. Resulting symptoms
can include behavioral dysfunction, headaches, diarrhea, and CNS disturbances.
Studies have noted a correlation between excessive body burden of ammonia and
Alzheimer's disease.41 Because alpha-ketoglutaric acid, important in the Citric Acid
Cycle, is also a major ammonia scavenger in the body, excess ammonia may deplete
alpha ketoglutarate in the Citric Acid Cycle, stalling energy transfer inside body
cells.42 Ammonia is either transported to the liver where it is fixed as the nontoxic
form urea in the urea cycle, or it is attached to the amino acid glutamate, forming
glutamine. Glutamine can act as a nitrogen shuttle, removing nitrogen from the CNS.
Impaired ammonia detoxification may be indicated by elevated glutamine,asparagine,
alanine, or glycine, as well as by elevated urea cycle intermediates (arginine,
citrulline, argininosuccinate, ornithine). Hyperammonemia may be confirmed with
a blood (venous) ammonia determination.
Inborn Errors of Metabolism
More than 70 inherited amino acidopathies are now known, all falling into two general classes: enzymatic defects in amino acid catabolism and disorders of transmembrane transport. The catabolic defects far outnumber the transport abnormalities.
Most of these disorders are rare, their incidences ranging from 1 in 12,000 for
phenylketonuria (PKU) to 1 in 200,000 for alkaptonuria.43 However, mild (hidden) homocystinuria is much more common, with an incidence estimated at 1 in 70 to 1 in 200.44,45
In general, the various disorders are named for the compound which accumulates to
highest concentration in blood or urine. Symptoms range from none to severe neurological dysfunction, and they are usually prevented or mitigated by appropriate
dietary amino acid restriction or vitamin supplementation.
© 2004 Genova Diagnostics
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Amino Acids Analysis Application Guide
Response (mV)
Plasma Amino Acid Chromatogram (shows partial results)
130
120
110
100
90
80
70
60
50
40
30
20
10
6
Glutamine
Urea
Valine
Alanine
Threonine
Taurine
Cysteine
Serine
Glycine
Leucine
Citrulline
Glutamic Acid
Asparagine
Isoleucine
Methionine
Phenylalanine
Tyrosine
Alpha-amino-n-butyric acid
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
Time (minutes)
Although the finding of a homozygous error in metabolism is uncommon, it is Dr. Jon
Pangborn's clinical observation that the frequency of occurrence is increased over
the general population in individuals who present with food and chemical intolerances, chronic illnesses, and degenerative disease conditions. Heterozygous conditions, usually mild errors or impairments in amino acid metabolism or transport, are
far more frequent. Mild cystinuria, a renal transport disorder, has been observed in
allergy and may occur in the general population with an incidence of 1 in 400. This
condition is usually accompanied by renal excretion of lysine, ornithine and arginine.46
Amino Acids Analysis
The Amino Acids Analysis employs state-of-the-art high performance liquid
chromatography (HPLC) to perform the most comprehensive and sensitive assay
available for urine or plasma analytes. The measured analytes are grouped on the
report into functional categories, including the nutritionally essential and semi-essential amino acids, dietary peptide-related analytes, the non-essential protein amino
acids, and the intermediary metabolites, providing information on nutrient cofactor
status and disorders relating to their imbalances. Commentary is thorough and takes
into account patterns of amino acids associated with specific organ systems or problem areas. Both urine and plasma analyses include control measurements to monitor
and alert to problems with sample quality or representativeness.
Urine versus Plasma
The body fluids that are most commonly assessed for amino acid content are urine
from a 24-hour collection and plasma following an overnight fast. 24-hr urine amino
acid measurements show what is high and what is low over a 24-hr period, provided
that renal function is reasonably normal. In contrast, blood plasma amino acid measurements show the levels of amino acids that are being transported at a point in time.
There are several advantages to starting with a 24-hour urine analysis. Urine analysis
reveals more distinctive patterns related to problems in enzymatic activity, nutrient
cofactor adequacy, and transport. Urine is also not subject to the circadian rhythm
variation in amino acids that is present in blood, and excesses or deficiencies over a
period of time can be more easily assessed. Many conditions of amino acid wasting,
e.g. cystinuria, are thus identifiable in urine samples. Due to renal conservation of
amino acids, urine levels typically drop before plasma levels. For these reasons, a
24-hour urine is more likely to reveal marginal deficiencies. Only severe deficiencies
will result in low values on both tests.
Plasma amino acids analysis may be preferred when age, toilet training, behavior, or
patient cooperation present as complicating factors. Other possible reasons for
selecting plasma analysis include severe malnutrition, anorexia, hematuria conditions
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Amino Acids Analysis Application Guide
(including menstruation), and rheumatoid arthritis, where the common pattern of low
histidine only shows in a plasma sample. If poor renal clearance or renal failure is
known beforehand, a blood plasma analysis is recommended. Also, in urinary wasting
conditions or in nephrotic syndromes, the plasma levels are indicative of status while
the urine levels serve to confirm the diagnosis.
For plasma sampling, an overnight, fasting measurement is conventional practice.
Such sampling reduces dietary influences and accentuates metabolic status.
A comprehensive workup to assess the gross metabolic state would include both
urine and plasma analyses, measured in the same time period, particularly for the
patient with degenerative disease or with severe intolerances to foods or environmental substances. If a choice must be made because of cost or other factors, urine
is preferred.
Amino Acids Therapies
The Amino Acids Analysis report includes a suggested schedule of amino acid supplements, based upon measured levels in blood plasma or urine. These levels are calculated based upon the measured level versus the reference range, the individual’s age and
sex, and a human needs tabulation derived from the National Research Council’s table
of amino acids requirements. Such supplements are to be prescribed by the practitioner, formulated and packaged by a qualified pharmacy, and taken orally by the patient.
Conclusion
Amino acids form the basic constituents of every living cell, and participate in myriad
biochemical reactions in the body. Significant progress in amino acid research now
provides practitioners with a wealth of information on amino acid imbalances and
related symptomatology. With such advances in amino acid research, information
can now be gleaned about protein and nutrient cofactor adequacy, enzyme functionality, predisposition to various degenerative disorders, wasting syndromes, gastrointestinal dysfunction, neurological disorders, impairments in detoxification, inborn
errors of metabolism, and a wide array of clinical conditions. Results can be utilized
in the design of specific replacement therapy, aimed at restoring balance where it is
needed. Amino Acids Analysis should be considered whenever a thorough nutritional
assessment is desired.
Related Tests to Consider
Comprehensive Digestive Stool Analysis (CDSA) and Intestinal Permeability:
Certain patterns of amino acids may suggest maldigestion, dysbiosis, or leaky gut.
Subnormal levels of nutritionally essential amino acids, particularly the branchedchain amino acids leucine, isoleucine, and valine, and/or increased levels of the peptides, anserine and carnosine, can alert the health care practitioner to the possibility
of madigestion and/or malabsorption. “Leaky gut” is commonly associated with this
picture. Irritation of the mucosal lining, apparent in inflammatory bowel disease, may
be reflected in an elevated hydroxyproline, a marker for cell turnover. A CDSA in such
cases may serve to confirm digestive or absorptive impairments, as well as reveal
complications resulting from them, such as dysbiosis, infection, or reduced immune
function. An Intestinal Permeability test may further reveal malabsorption or a "leaky
gut" resulting from these imbalances.
Some amino acids that are intermediates in human metabolism are also intermediate
or end products of microbial metabolism. Elevations of GABA, alpha-aminoadipic
acid, beta-alanine, and others may be consistent with gut dysbiosis.
Detoxification Profile/Oxidative Stress:
Subnormal levels of amino acids involved in the body's detoxification processes can
indicate impairments in this area. Phase II conjugation reactions, as well as antioxidant activity, are extremely dependent on the availability of amino acid precursors,
particularly the sulfur-bearing amino acids such as methionine, cysteine, glutathione,
and taurine. Inadequate reserves can result in poor clearance of xenobiotics and
endogenous compounds, as well as oxidative stress. Any system may be impacted,
from the mitochondria and cell membranes to the neurological and immune systems.
An Oxidative Stress or Comprehensive Detoxification Profile (including markers for
oxidative stress) can help determine detoxification capacity, specific imbalances, and
free radical damage, so that specific nutritional support may be selected.
© 2004 Genova Diagnostics
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Amino Acids Analysis Application Guide
Therapeutic Uses
of Amino Acids
Alanine, Glycine, and Glutamic Acid:
Benign prostatic hypertrophy.47,48
Arginine: Wound healing,49 infertility,50
heart attack and stroke prevention,51
hypertension,52 chronic fatigue,
especially muscular fatigue with
myalgia.53
Carnitine: Heart disease,54,55 myopathy,56 hyperlipidemias,57 alcoholism.58
Cysteine, N-Acetylcysteine (NAC), or
Glutathione: Intolerance to xenobiotics, detoxification impairments,59
free radical-associated disorders,60,61
pulmonary conditions,62,63 AIDS.64
Glutamine: GI repair,65 total parenteral
nutrition (TPN),66 wasting disorders,67
immune support,68 chemotherapy
side effects,69 surgery,70 burns,71
alcoholism.72
Glycine: Detoxification impairments,
wound healing.73
Histidine: Rheumatoid arthritis.74
Leucine, isoleucine, and valine:
Alcoholism,75 surgery, starvation, or
infection,76 muscle building,77 TPN.78
Lysine: Herpes simplex (HSV-1, HSV-2).79
Elemental Analysis:
Several patterns in the Amino Acids Analysis are suggestive of mineral imbalances
which may be further elucidated by Elemental Analysis, a profile of nutrient and toxic
elements. Magnesium insufficiency, for example, may be suggested by high levels of
ethanolamine, phosphoserine, and citrulline, and low levels of their downstream
metabolites, phosphoethanolamine, serine, and argininosuccinic acid, respectively.
Elevated ammonia may suggest insufficient manganese and/or aluminum toxicity.
Patterns suggestive of maldigestion and malabsorption should alert the physician to
the possibility of broad spectrum nutrient insufficiencies, along with the need for
further investigation.
Comprehensive Cardiovascular Assessment
Proper methionine metabolism is imperative for proper cardiovascular function.
Abnormal levels of related amino acids, particularly elevated homocysteine and
subnormal taurine, have been noted in atherosclerosis and other cardiovascular
disorders. When either of these imbalances are apparent in the Amino Acids Analysis,
or when the pattern of amino acids suggests low magnesium, a thorough cardiovascular assessment is recommended in order to determine additional CV abnormalities and
appropriate intervention. The Comprehensive Cardiovascular Assessment identifies
ten markers associated with development of cardiovascular disease.
Bone Resorption Assessment
Osteoporosis is an insidious process which is usually not evident until a fracture has
finally occurred, typically after significant bone calcium has already been lost. Several
amino acid markers can help alert the physician to increased likelihood of the disorder, including elevated homocysteine, deficient cystathionine, and elevated hydroxyproline. Excess homocysteine can interfere with proper crosslinking of collagen,
including that of bone; elevated levels of the amino acid have been noted in osteoporotic individuals.101 Elevated hydroxyproline may also imply increased resorption,
especially if accompanied by other allusive markers. As proper mineral nutrition is
essential to bone health, patterns of amino acids suggestive of maldigestion, malabsorption, or mineral insufficiencies may suggest inadequate reserves for the maintenance of healthy bones. The Bone Resorption Assessment can help determine the rate
of current bone loss and monitor the efficacy of therapeutic intervention.
Phenylalanine, tyrosine: Depression,80
Parkinson’s disease,81 pain,82 vitiligo.83
S-Adenosylmethionine (SAM):
Depression,84 osteoarthritis,85
fibromyalgia,86 liver disorders.87
Taurine: Intolerance to chlorine,
hypochlorite (bleach), phenols,
nitrites, amines, or aldehydes,88,89 fat
malabsorption in cystic fibrosis,90
seizures,91 eye disorders,92 gallbladder
disease,93 heart disease,94 alcoholism.95
Tryptophan: Insomnia, depression,96
restless leg syndrome,97 alcoholism,98
weight control,99 Parkinson's disease.100
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Amino Acids Analysis Application Guide
References
1 Matthews DM. Intestinal absorption of peptides. Physiol Rev
1975;55:537-608.
2 Ehrenpreis S. D-phenylalanine and other enkephalinase inhibitors as
pharmacological agents: implications for some important therapeutic
application. Acupunct Electrother Res 1982;7(2-3):157-172.
3 Boushey C, Beresford S, Omenn G, Motulsky A. A quantitative assessment of plasma homocysteine as a risk factor for vascular disease.
Probable benefits of increasing folic acid intakes. JAMA
1995;274:1049-1057.
4 Steegers-Theunissen R, Boers G, Trijbels F, Eskes T. Neural-tube
defects and derangements of homocysteine metabolism [letter].
N Engl J Med 1991;324:199-200.
25 Klimberg VS, Salloum RM, Kasper M, Plumley DA, Dolson DJ,
Hautamaki RD, et al. Oral glutamine accelerates healing of the small
intestine and improves outcome after whole abdominal radiation.
Arch Surg 1990; 125(8):1040-1045.
26 Scriver CR, Gibson K. Disorders of Beta and Gamma Amino Acids in
Free and Peptide-linked Forms. In: Scriver C, Beaudet A, Sly W, Valle
D, editors. The metabolic and molecular bases of inherited disease.
Vol 1. 7th Ed. New York: McGraw-Hill Book Company, 1995: 13491370.
27 Crabbe P, Isselbacher KJ. Urinary hydroxyproline excretion in malabsorption states:. Gastroenterology 1965;48(3):307-311.
48 Feinblatt HM, Gant JC. Palliative treatment of benign prostatic hypertrophy: value of glycine, alanine, glutamic acid combination. J Maine
M Ass 1958:46:99-102.
49 Meyer NA, Muller MJ, Herndon DN. Nutrient support of the healing
wound. New Horiz 1994;2(2):202-214.
50 Schachter A, Goldman JA, Zukerman Z. Treatment of oligospermia
with the amino acid arginine. J Urol 1973;110(3):311-313.
51 Wolf A, Zalpour C, Theilmeier G, Wang BY, Ma A, Anderson B, et al.
Dietary L-arginine supplementation normalizes platelet aggregation in
hypercholesterolemic humans. J Am Coll of Cardio1997;29(3):479-485.
28 Crabbe P, Isselbacher KJ. Urinary hydroxyproline excretion in malabsorption states. Gastroenterology 1965;48(3):307-311.
52 Creager MA, Gallagher SJ, Girerd XJ, Coleman SM, Dzau VJ, Cooke
JP. L-arginine improves endothelium-dependent vasodilation in hypercholesterolemic humans. J Clin Invest 1992: 90(4):1248-1253.
29 Kinscherf R, Fischbach T, Mihm S, Roth S, Hohenhaus-Sievert E,
Weiss C, et al. Effect of glutathione depletion and oral N-acetyl cysteine treatment on CD4+ and CD8+ cells. FASEB J 1994;8(6):448-451.
53 Roberts CK, Barnard RJ, Scheck SH, Balon TW. Exercise-stimulated
glucose transport in skeletal muscle is nitric oxide dependent. Am J
Physiol 1997;273(1):E220, E225.
30 Jeevanandam M, Young DH, Ramias L, Schiller WR. Amino aciduria
of severe trauma. Am J Clin Nutr 1989;49:815-822.
31 Beutler E, Gelbart T. Plasma glutathione in health and in patients with
malignant disease. J Lab Clin Med 1985;105(5):581-584.
54 Cherchi A, Lai C, Angelino F, Trucco G, Caponnetto S, Mereto PE, et al.
Effects of L-carnitine on exercise tolerance in chronic, stable angina:
a multicenter, double-blind, randomized, placebo controlled crossover
study. Int J Clin Pharmacol Ther Toxicol 1985; 23(10):569-572.
8 Lauterburg BH, Corcoran GB, Mitchell JR. Mechanism of action of Nacetylcysteine in the protection against the hepatotoxicity of acetaminophen in rats in vivo. J Clin Invest 1983; 71(4):980-991.
32 Ogasawara M, Nakamura T, Koyama I, Nemoto M, Yoshida Tl.
Reactivity of taurine with aldehydes and its physiological role. Adv
Exp Med Biol 1994;359:71-78.
55 DiPalma JR, Ritchie DM, McMichael RF. Cardiovascular and antiarrhythmic effects of carnitine. Arch Int Pharmacdyn Ther 1975;
217(2):246-250.
9 de Quay B, Malinverni R, Lauterburg BH. Glutathione depletion in HIVinfected patients: role of cysteine deficiency and effect of oral Nacetylcysteine. AIDS 1992;6(8):815-819.
33 Timbrell JA. Toxic responses to foreign compounds. In: Principles of
biochemical toxicology, 2nd ed. London and Bristol, PA: Taylor &
Francis Inc, 1994:221-232.
10 Droge W, Eck HP, Naher H, Pekar U, Daniel V. Abnormal amino acid
concentrations in the blood of patients with acquired immunodeficiency syndrome (AIDS) may contribute to the immunological defect.
Biol Chem Hoppe-Seyler 1988;369(3):143-148.
34 Boushey C, Beresford S, Omenn G, Motulsky A. A quantitative assessment of plasma homocysteine as a risk factor for vascular disease.
Probable benefits of increasing folic acid intakes. JAMA
1995;274(13):1049-1057.
56 Giamberardino MA, Dragani L, Valente R, Di Lisa F, Saggini R,
Vecchiet L. Effects of prolonged L-carnitine administration on delayed
muscle pain and CK release after eccentric effort. Int J Sports Med
1996;17(5):320-4.
11 Buhl R, Jaffe HA, Holroyd KJ, Wells FB, Mastrangeli A, Saltini C,
Cantin AM, Crystal RG. Systemic glutathione deficiency in symptomfree HIV seropositive individuals. Lancet 1989;2(8675):1294-1298.
35 Selhub J, Jacques PF, Bostom AG, D'Agostino RB, Wilson PW,
Belanger AJ, et al. Association between plasma homocysteine concentrations and extracranial carotid-artery stenosis. N Engl J Med
1995;332(5):286-291.
5 Seashore MR, Durant JL, Rosenberg LE. Studies of the mechanism of
pyridoxine-responsive homocystinuria. Pediatr Res 1972; 6(3):187-196.
6 Bell KM, Potkin SG, Carreon D, Plon L. S-adenosylmethionine blood
levels in major depression: changes with drug treatment. Acta Neurol
Scand Suppl 1994;154:15-18.
7 Meldrum MJ, Tu R, Patterson T, Dawson R Jr, Petty T. The effect of
taurine on blood pressure, and urinary sodium, potassium and calcium
excretion. Adv Exp Med Biol 1994; 359:207-215.
12 Lomaestro BM, Malone M. Glutathione in health and disease: pharmacotherapeutic issues. Ann Pharmocother 1995; 29(12):1263-73.
13 Civitelli R, Villareal DT, Agnusdei D, Nardi P, Avioli LV, Gennari C.
Dietary L-lysine and calcium metabolism in humans. Nutrition 1992;
8(6):400-405.
14 Kendler BS. Carnitine: an overview of its role in preventive medicine.
Prev Med 1986; 15(4):373-390.
15 Azzara A, Carulli G, Sbrana S, Rizzuti-Gullaci A, Minnucci S, Natale M,
et al. Effects of lysine-arginine association on immune functions in
patients with recurrent infections. Drugs Exp Clin Res 1995;21(2):71-78.
16 Drexler H, Zeiher AM, Meinzer K, Just H. Correction of endothelial
dysfunction in coronary microcirculation of hypercholesterolaemic
patients by L-arginine. Lancet 1991;338(8782-8783):1546-1550.
17 Wolf A, Zalpour C, Theilmeier G, Wang BY, Ma A, Anderson B, Tsao
PS, Cooke JP. Dietary L-arginine supplementation normalizes platelet
aggregation in hypercholesterolemic humans. J Am Coll Cardiol
1997;29(3):479-485.
18 Brzozowski T, Konturek SJ, Drozdowicz D, Dembinski A, Stachura J.
Healing of chronic gastric ulcerations by L arginine. Role of nitric
oxide, prostaglandins, gastrin and polyamines. Digestion 1995;
56(6):463-71.
19 Maurizi CP. The therapeutic potential for tryptophan and melatonin:
possible roles in depression, sleep, Alzheimer's disease and abnormal aging. Med Hypotheses 1990; 31(3):233-242.
20 Lucca A, Lucini V, Piatti E, Ronchi P, Smeraldi E. Plasma tryptophan
levels and plasma tryptophan/neutral amino acids ratio in patients
with mood disorder, patients with obsessive-compulsive disorder, and
normal subjects. Psychiatry Res 1992;44(2):85-91.
21 van der Hulst RR, van Kreel BK, von Meyenfeldt MF, Brummer RJ,
Arends JW, Deutz NE, Soeters PB. Glutamine and the preservation of
gut integrity. Lancet 1993;3 41(8857):1363-1365.
22 Souba WW, Klimberg VS, Plumley DA, Salloum RM, Flynn TC, Bland
KI, Copeland EM. The role of glutamine in maintaining a healthy gut
and supporting the metabolic response to injury and infection. J Surg
Res 1990;48(4):383-391.
23 Fox AD, Kripke SA, De Paula J, Berman JM, Settle RG, Rombeau JL.
Effect of a glutamine supplemented enteral diet on methotrexateinduced enterococolitis. JPEN 1988; 12(4):325-331.
24 Klimberg VS, Souba WW, Dolson DJ, Salloum RM, Hautamaki RD,
Plumley DA, et al. Prophylactic glutamine protects the intestinal
mucosa from radiation injury. Cancer 1990; 66(1):62-68.
© 2004 Genova Diagnostics
36 Landgren F, Israelsson B, Lindgren A, Hultberg B, Andersson A,
Brattstrom L. Plasma homocysteine in acute myocardial infarction:
homocysteine-lowering effect of folic acid. J Intern Med
1995;237(4):381-388.
37 Chasan-Taber L, Selhub J, Rosenberg IH, Malinow MR, Terry P, Tishler
PV, et al. A prospective study of folate and vitamin B6 and risk of
myocardial infarction in US physicians. J Am Coll Nutr
1996;15(2):136-143.
38 Brattstrom L, Lindgren A, Israelsson B, Malinow MR, Norrving B,
Upson B, et al. Hyperhomocysteinaemia in stroke: prevalence, cause,
and relationships to type of stroke and stroke risk factors. Eur J Clin
Invest 1992; 22(3):214-221.
39 Reinstein DK, Lehnert H, Wurtman RJ. Dietary tyrosine suppresses
the rise in plasma corticosterone following acute stress in rats. Life
Sci 1985;37(23):2157-2163.
40 Bell KM, Potkin SG, Carreon D, Plon L. S-adenosylmethionine blood
levels in major depression: changes with drug treatment. Acta Neurol
Scand Suppl 1994;154:15-18.
41 Fisman M, Gordon B, Feleki V, Helmes E, Appell J, Rabheru K.
Hyperammonemia in Alzheimer's disease. Am J Psychiatry 1985;
142(1):71-73.
42 Rodwell, VW. Catbolism of amino acid nitrogen. In: Martin, DW,
Mayes, PA, Rodwell VW, editors. Harper's review of biochemistry. Los
Altos, CA: Lange Medical Publications, 1993: 276-277..
43 MMBID-7 summary table. In: Scriver CR, Beaudet AL, Sly WS, Valle
D, editors. The metabolic and molecular bases of inherited disease.
Vol 1. 7th ed. New York: McGraw-Hill, Inc, 1995:5-9.
44 Boers GH, Smals AG, Trijbels FJ, Fowler B, Bakkeren JA,
Schoonderwaldt HC. Heterozygosity for homocystinuria in premature
peripheral and cerebral occlusive arterial disease. N Engl J Med
1985;313(12):709-715.
45 Mudd SH et al. Disorders of transsulfuration. In: Scriver CR, Beaudet
AL, Sly WS, Valle D, editors. The metabolic and molecular bases of
inherited disease. Vol 1. 7th ed. New York: McGraw-Hill, Inc,
1995:1279, 1328.
46 Pangborn J. Amino acid analysis and therapy: opportunities and pitfills. In: Hank J, editor. Treatment options in energetic, functional, biologic medicine. Syllabus for the Great Lakes College of Clinical
Medicine Symposium; 1997 Feb 28-Mar 2; Asheville (NC):7.
47 Miller, AL. Benign prostatic hyperplasia: nutritional and botanical
therapeutic options. Alt Med Rev 1996;1:18-25.
9
57 Borum PR. Carnitine and lipid metabolism. Bol Asoc Med P R
1991;83(3):134-135.
58 Sachan DS, Rhew TH, Ruark RA. Ameliorating effects of carnitine and
its precursors on alcohol-induced fatty liver. Amer J Clin Nutr 1984;
39(5):738-744.
59 Shetty TK, Francis AR, Bhattacharya RK. Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of sulphur-containing amino acids. Mutat Res 1989;222(4):403-407.
60 Hagen TM, Aw TY, Jones DP. Glutathione uptake and protection
against oxidative injury in isolated kidney cells. Kidney Intl 1988;
34(1):74-81.
61 Lash LH, Hagen TM, Jones DP. Exogenous glutathione protects intestinal epithelial cells from oxidative injury. Pro Natl Acad Sci USA
1986; 83(13):4641-4645.
62 Testa B, Mesolella M, Testa D, Giuliano A, Costa G, Maione F, et al.
Glutathione in the upper respiratory tract. Ann Otol Rhinol Larynogol
1995;104(2):117-122.
63 Green GM. Cigarette Smoke: Protection of alveolar macrophages by
glutathione and cysteine. Science 1968;162(855):810-811.
64 Roederer M, Staal FJ, Ela SW, Herzenberg LA, Herzenberg LA. Nacetylcysteine: potential for AIDS therapy. Pharm 1993;46(3):121-129.
65 Buchman AL. Glutamine: Is it a conditionally required nutrient for the
human gastrointestinal system? J Am Coll Nutr 1996;15(3):199-205.
66 Platell C, McCauley R, McCulloch R, Hall J. The influence of parenteral glutamine and branched-chain amino acids on total parenteral
nutrition-induced atrophy of the gut. J Parenter Enteral Nutr
1993;17(4):348-354.
67 Welbourne TC, Joshi S. Enteral glutamine spares endogenous glutamine in chronic acidosis. J Parenter Enteral Nutr 1994;
18(3):243-47.
68 Alverdy JC. Effects of glutamine-supplemented diets on immunology
of the gut. J Parent Ent Nutr 1990;14(4):109S-113S.
69 Klimberg VS, Nwokedi E, Hutchins LF, Pappas AA, Lang NP,
Broadwater JR, et al. Glutamine facilitates chemotherapy while
reducing toxicity. J Parent Ent Nutr 1992;16(6):83S-87S.
70 Kapadia CR, Colpoys MF, Jiang ZM, Johnson DJ, Smith RJ, Wilmore
DW. Maintenance of skeletal muscle intracellular glutamine during
standard surgical trauma. J Parenter Enteral Nutr 1985;9(5):583-589.
71 Aulick LH, Wilmore DW. Increased peripheral amino acid release following burn injury. Surgery 1979;85(5):560-565.
72 Rogers LL , Pelton DB, Williams RJ. Voluntary alcohol consumption by
rats following administration of glutamine. J Biol Chem 1956;
220(1):321-323.
73 Harvey SG, Gibson JR. The effects on wound healing of three amino
acids- a comparison of two models. Brit J Dermatol 1984;
111(27):171-173.
Amino Acids Analysis Application Guide
References
74 Pinals RS, Harris ED, Burnett JB, Gerber DA. Treatment of rheumatoid
arthritis with L-histidine: a randomized, placebo controlled, doubleblind trial. J Rheumatol 1977;4(4):414-419.
83 Cormane RH, Siddiqui AH, Westerhof W, Schutgens RB.
Phenylalanine and UVA light for the treatment of vitiligo. Arch
Dermatol Res 1985;277(2):126-130.
75 Bernardini P, Fischer JE. Amino acid imbalance and hepatic
encephalopathy. Annu Rev Nutr 1982;2:419-454.
84 Bressa GM. S-adenosyl-L-methionine (SAMe) as antidepressant:
meta-analysis of clinical studies. Acta Neurol Scand Suppl 1994;
154:7-14.
76 Blackburn GL, Moldawer LL, Usui S, Bothe A Jr, O'Keefe SJ, Bistrian
BR. Branched chain amino acid administration and metabolism during
starvation, injury, and infection. Surgery 1979;86(2):307.
85 di Padova C. S-adenosylmethionine in the treatment of osteoarthritis.
Review of the clinical studies. Am J Med 1987;83(5A):60-65.
77 Louard RJ, Barrett EJ, Gelfand RA. Effect of infused branched-chain
amino acids on muscle and whole-body amino acid metabolism in
man. Clin Sci (Colch) 1990;79(5):457-466.
86 Jacobsen S, Danneskiold-Samsoe B, Andersen RB. Oral S-adenosylmethionine in primary fibromyalgia -double-blind clinical evaluation.
Scand J Rheumatol (SWEDEN) 1991; 20(4):294-302.
78 Platell C, McCauley R, McCulloch R, Hall J. The influence of parenteral glutamine and branched-chain amino acids on total parenteral
nutrition-induced atrophy of the gut. J Parenter Enteral Nutr
1993;17(4):348-354.
87 Osman E, Owen JS, Burroughs AK. Review article: S-adenosyl-Lmethionine--a new therapeutic agent in liver disease? Aliment
Pharmacol Ther 1993;7(1):21-28.
79 Griffith RS, Walsh DE, Myrmel KH, Thompson RW, Behforooz A.
Success of L-lysine therapy in frequently recurrent herpes simplex
infection. Treatment and prophylaxis. Dermatologica 1987;175(4):183190.
80 Fischer E, Heller B, Nachon M, Spatz H. Therapy of depression by
phenylalanine. Arzneimittelforschung 1975;25(1):132.
81 Lemoine P, Robelin N, Sebert P, Mouret J. L-tyrosine: A long-term
treatment of Parkinson's disease. C R Acad Sci [III] 1989;309(2):43-47.
82 Ehrenpreis S. D-phenylalanine and other enkephalinase inhibitors as
pharmacological agents: implications for some important therapeutic
application. Acupunct Electrother Res 1982;7(2-3):157-172.
88 Pangborn JB. Metabolism Aspects of Chemical Sensitivities. In:
Second Annual International Symposium on Man and His
Environment in Health and Disease Feb 17, 1984. Environmental
Health Center, Dallas, TX.
89 Rea WJ. Nutritional status and pollutant overload. In: Chemical sensitivity. Vol 1: Chemical sensitivity: principles and mechanisms. Boca
Raton, FL: CRC Press, 1992:257-258.
90 Belli DC, Levy E; Darling P, Leroy C, Lepage G, Giguere R, Roy CC.
Taurine improves the absorption of a fat meal in patients with cystic
fibrosis. Pediatrics 1987;80(4):517-523.
91 Barbeau A, Donaldson J. Zinc, taurine, and epilepsy. Arch Neurol
1974;30(1):52-58.
93 Nakamura-Yamanaka Y, Tsuji K, Ichikawa T. Effect of dietary taurine
on cholesterol 7 alpha-hydroxylase activity in the liver of mice fed a
lithogenic diet. J Nutr Sci Vitaminol (Tokyo) 1987;33(3):239-243.
94 Azuma J, Hasegawa H, Sawamura A, Awata N, Harada H, et al.
Taurine for treatment of congestive heart failure. Int J Cardiol 1982;
2(2):303-304.
95 Ikeda H. Effects of taurine on alcohol withdrawal [letter]. Lancet
1977;2(8036):509.
96 Benkelfat C, Ellenbogen MA, Dean P, Palmour RM, Young SN. Moodlowering effect of tryptophan depletion. Enhanced susceptibility in
young men at genetic risk for major affective disorders. Arch Gen
Psychiatry 1994; 51(9):687-697.
97 Sandyk R. L-tryptophan in the treatment of restless legs syndrome.
[letter]. Am J Psychiatry 1986;143(4):554-555.
98 Westrick ER, Shapiro AP, Nathan PE, Brick J. Dietary tryptophan
reverses alcohol-induced impairment of facial recognition but not verbal recall. Alcohol Clin Exp Res 1988; 12(4):531-533.
99 Morris P, Li ET, MacMillan ML, Anderson GH. Food intake and selection after peripheral tryptophan. Physiol Behav 1987;40(2):155-163.
100 Coppen A, Metcalfe M, Carroll JD, Morris JG. Levodopa and L-tryptophan therapy in Parkinsonism. Lancet 1972;1(752):654-657.
101 Lubec B, Fang-Kircher S, Lubec T, Blom HJ, Boers GH. Evidence for
McKusick’s hypothesis of deficient collagen cross-linking in patients
with homocystinuria. Biochem Biophys Acta 1996;1315(3):159-62.
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92 Hayes KC, Carey RE, Schmidt SY. Retinal degeneration associated
with taurine deficiency in the cat. Science 1975;188(4191):949-51.
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