Ch. 18 - Trace Elements Flashcards
An element is considered _____ if a deficiency impairs a biochemical or functional process.
Essential
What would be the treatment for the deficiency of an essential element?
Replacement
This type of trace element is of medical interest primarily because many of them are toxic.
Nonessential
The essential trace elements are often associated with an enzyme called _____ or a protein called _____ as a cofactor.
Metalloenzyme
Metalloprotein
This is a crystalline, silver-white ductile metal.
It is the most abundant metal on earth.
Aluminum (Al)
The human body absorbs how much of inhaled aluminum?
1.5% - 2%
The human body absorbs how much of ingested (orally taken) aluminum?
0.01% - 5%
The absorption efficiency of aluminum is dependent on what factors?
Chemical form
Particle size
Dietary exposure to chelators
What are the chelating agents to aluminum?
Citric and Lactic acid
In plasma, Al is bound to carrier proteins such as _____.
Transferrin
Al binds to various _____ in the blood and distributes to every organ.
Ligands
How much of the Al in the body is found in the bone?
50%
How much of the Al in the body is found in lung tissue?
25%
How much of the Al in the body is excreted through urine?
95%
How much of the Al in the body is excreted in the bile?
2%
The amount of Al in this body organ increases with age.
Lungs
This trace element has been shown to interfere with enzymatic processes and will produce encaphalopathy in animals.
Aluminum
What are the signs and symptoms of Al toxicity?
Encephalopathy Osteomalacia/aplastic bone disease (painful spontaneous fractures, hypercalcemia, and tumor calcinosis) Proximal myopathy Increased risk of infection Microcytic anemia Increased left ventricular mass Decreased myocardial function
What are the clinical manifestations of Al toxicity?
Anemia
Bone disease
Progressive dementia with inc. conc. of Al in the brain
Al toxicity can cause what disease in infants?
Impaired neurologic development
This is a ubiquitous element displaying both metallic and non-metallic properties.
Arsenic (As)
This is the largest source of As exposure for most people.
Food
What is the main current use of As?
Wood preservative
Enumerate other current and past uses of As.
Pesticides Pigments Poison gases Ammunition manufacturing Semiconductor proecessing Medicines
The clinical signs and symptoms of As exposure depends on these factors.
Duration and extent of exposure to organic and methylated species of As
Underlying clinical status of patient
What are the symptoms for acute As exposure?
Gastrointestinal (nausea, emesis, abdominal pain, rice water diarrhea)
Bone marrow (Pancytopenia, anemia, basophilic stippling)
Cardiovascular (ECG changes)
CNS (Encephalopathy, polyneuropathy)
Renal (Renal insufficiency, renal failure)
Hepatic (Hepatitis)
What are the symptoms for chronic As exposure?
Dermatologic (Mees’ line, hyperkeratosis, hyperpigmentation, alopecia)
Hepatic (Cirrhosis, hepatomegaly)
Cardiovascular (Hypertension, peripheral vascular disease [PVD])
CNS (“Socks and gloves” neuropathy, tremor)
Malignancies (Squamous cell, hepatocellular, skin, bladder, lung, renal carcinoma)
What are the symptoms for chronic As exposure specifically concerning the CNS?
“Socks and gloves” neuropathy
Tremor
Chronic exposure to As has been shown to cause _____, a severe form of PVD which leads to gangrenous changes.
Blackfoot disease
What are the dermatological symptoms for chronic As exposure?
Mees’ line
Hyperkeratosis
Hyperpigmentation
Alopecia
What are the chelating agents for As poisoning?
Dimercaprol (aka. British anti-Lewisite)
Penicillamine
Succimer
Arsenic trioxide can be used for the treatment of what disease?
Acute Promyelocytic leukemia
What are the main routes for As exposure?
Ingestion
Inhalation
What are the organic forms of As?
Arsenocholine
Arsenobetaine
This form of As is commonly found in fish and seafood , are considered relatively non-toxic, and are cleared rapidly.
Organic form
This form/species of As are highly toxic and occur naturally in rocks, soil, and groundwater.
Inorganic form
This form/species of As are intermediate in toxicity and arise primarily from metabolism of inorganic As, but small amounts may arise from food.
Methylated
Give examples of organic methylated As compounds.
Monomethylarsonic acid (MMA) Dimethylarsenic acid (DMA)
This organic methylated arsenic compound was formed by the hepatic metaolism of As(3+).
Monomethylarsonic acid (MMA)
This organic methylated arsenic compound was formed by the hepatic metaolism of As(5+).
Dimethylarsenic acid (DMA)
(T/F) Inorganic methylated forms are more toxic than its organic counterparts and they are eliminated slowly, usually 1 - 3 weeks.
F (Inorganic less toxic than organic (As3+ and As 5+)
This is a soft bluish-white metal that can be easily cut with a knife.
Cadmium (Cd)
What are the most common uses of Cd?
Manufacture of pigments, batteries, metal plating, plastic
What is the largest source of airborne Cd exposure?
Burning of fossil fuel
Incineration of municipal waste
What is the chelating agent for Cd exposure/
EDTA
What is the reference dose for Cd in drinking water?
0.0005 mg/kg/d
What is the reference dose for dietary exposure to Cd?
0.001 mg/kg/d
Absorption of Cd is (higher/lower) in females than in males due to differences in iron stores.
Higher
How much of inhaled Cd is absorbed in the body?
10-50%
For nonsmokers, what is the primary source of Cd exposure?
Ingested food
A what percent of the ingested Cd is excreted in the feces due to the low absorbance of Cd from the gut?
90%
Inhaled Cd can cause what toxic effects?
Respiratory distress Lung damage (Emphysema-like symptoms)
Acute Cd exposure can cause what toxic effects?
Nausea
Vomiting
Abdominal pain
Chronic Cd exposure can cause what toxic effects?
Slow onset of preteinuria
The toxicity of Cd is believed to be a result of _____ causing denaturation of the associated proteins, resulting in a loss of function.
Protein-Cd adducts
This element comes from the Greek word chroma meaning color.
Chromium (Cr)
This is the 21st most abundant element
Cr
What are the most common uses of Cr?
Manufacturing stainless steel Wood treatment Chrome plating Leather tanning Lead chromate or strontium chromate paints
What are the two main valencies of Cr?
Trivalent Cr(3+) Hexavalent Cr(6+)
(T/F) Cr(6+) is better absorbed and much more toxic that Cr(3+)
T
This element is responsible for the red color of rubies and the green color of emerald.
Chromium (Cr)
This proteins bind the newly absorbed Cr at site B.
Transferrin
This as an acceptor and transporter of Cr when transferrin sites are saturated.
Albumin
Aside from transferrin and albumin, enumerate other plasma proteins that can bind Cr.
Beta-globulins
Gamma-globulins
Lipoproteins
This element is an essential dietary element and plays a role in maintaining normal metabolism of glucose, fat, and cholesterol..
Chromium (Cr(3+))
What is the estimated safe and adequate daily intake of Cr for adults?
50 - 200ug/d
Intracellularly, this valence state of CR is reduced to reactive intermediates, producing free radicals and oxidizing deoxyribonucleic acid (DNA), both potentially inducing cell death.
Cr(6+)
What is the primary means for Cr to enter the body?
Ingestion
Inhalation
What is the mode of excretion of Cr?
Urine
Cr deficiency is characterized by what conditions?
Glucose inteolerance Glycosuria Hypercholesterolemia Decreased longevity Decreased sperm counts Impaired fertility
Contact with Cr(6+) salts can induce what conditions?
Severe dermatitis
Skin ulcers
Cr(3+/6+)-protein complex is responsible for allergic reactions due to Cr toxicity
Cr(3+)
(Low/High)-dose, (chronic/acute) Cr exposure typically results in transient renal effects.
Low
Chronic
This element is known to be a soft yet tough metal with excellent electrical and heat conducting properties.
Copper (Cu)
What are the four oxidation states of Cu?
Cu(0-3+)
Among the oxidation states of Cu, what is the most stable?
Cu(2+)
This element is an importnant cofactor for several metalloenzymes and is critical for reduction of iron in heme synthesis.
Copper (Cu)
How much of ingested copper is absorbed from the intestines?
50% - 80%
What is the average daily intake of Cu?
10 mg or more
At low concentrations, how is copper transported by the intestines?
Active transport