Final: Selenium (Se) Flashcards
What is Se a component of?
Glutathione peroxidase (Glutathione itself does NOT contain Se!)
What is glutathione peroxidase and what does it do?
Enzyme that protects the cytosol of cells against free radical oxidative damage.
What is Se critical for?
thyroid hormone production
What do selenoproteins seem to be important in?
Muscle - cardiac and skeletal
What disease does Se deficiency lead to in lambs and calves?
White muscle disease (degeneration of muscle)
What 3 free radicals does glutathione peroxidase take care of?
- Superoxide anion
- Hydrogen peroxide
- Hydroxyl radical
What is the Se-containing protein that is important for thyroid hormone production?
Iodothyronine 5’-deiodinase
What organ is Se incorporated in and how?
Liver; into methionine and cysteine
What is the major site for Se absorption and how much is absorbed?
duodenum, 90%
How is homeostasis of Se regulated?
By controlling urinary excretion of Se.
What happens when dietary Se is in great excess?
It is expired in the breath as dimethylselenide
What are dietary sources of Se?
Dirt from crops, wheat, fish
What does Se deficiency cause in most species?
Infertility and poor growth
How can negative effects of Se deficiency be reduced?
By vitamin E supplementation
Symptoms of what other deficiency are often shared with symptoms of Se deficiency?
Vit E
What are two diseases associated with Se deficiency in poultry?
- Exudative diathesis of broilers
2. Pancreatic fibrosis
What happens in exudative diathesis of broilers?
Generalized edema (begins in breast, wing, and neck)
Due to abnormal permeability of the capillaries
Gives skin a greenish blue discoloration, glistening appearance to underlying muscles
Growth is slow, mortality is high
What happens in pancreatic fibrosis of poultry?
Atrophy of the pancreas in young chicks
Results in subnormal amts of lipase and trypsin secretion interfering with lipid digestion
What Se deficiency does Vitamin E NOT prevent?
pancreatic fibrosis
What are two diseases associated with Se deficiency in pigs and what other mineral can also cause them?
- Hepatosis diaetetica
- Mulberry heart disease
Can both also be caused by vitamin E deficiency
What happens in hepatosis diaetetica?
Growing pigs 3-25 weeks of age; associated with necrotic liver lesions
What happens in Mulberry heart disease?
3-10 week old pigs; hemorrhagic/necrotic lesions in heart muscle –> red mottled appearance
Leads to reduced heart function and transudation of fluids into serous cavities and circulatory failure
What happens in white muscle disease?
Necrotic changes in striated muscles
Named for white striations observed in muscles of body (esp. thigh and shoulder)
Lesions bilaterally symmetrical and serum aspartic aminotransferase activity will be elevated
What are symptoms in an animal with white muscle disease?
Reluctant to stand, unsteady
When lifted and let go he is unable to catch himself
What occurs in Se-deficient dairy cows?
Retained placenta (sometimes mastitis)
What are 3 Se supplements and how well are they absorbed?
- Sodium selenite (absorption not mentioned)
- Sodium selenate decahydrate (absorpbed fairly well, retained only if incorporated into cysteine or methionine)
- Selenomethionine (organic form, very well absorbed and retained)
What are symptoms of Se toxicity?
Hepatic and renal damage, hemorrhagic exudate in lungs, ascites, blindness, stumbling.
Gastroenteritis possible
How many mg of Se and Vit E are in 1 ml of BoSe?
1 mg Se, 50 mg Vit E
How many mg of Se and Vit E are in 1 ml of MuSe?
5 mg Se, 50 mg Vit E
How many mg of Se and Vit E are in 1 ml of Myosel B?
1 mg Se, 50 mg Vit E
How many mg of Se and Vit E are in 1 ml of Myosel E?
2.5 mg Se, 50 mg Vit E
How many mg of Se and Vit E are in 1 ml of Myosel M?
5 mg Se, 50 mg Vit E
What are 2 diseases caused by Se toxicity in cattle and horses?
- Blind staggers
2. Alkali disease
What happens in blind staggers?
ACUTE Se poisoning caused by intake of certain plants such as woody aster, princesplume, and milkvetch.
What happens in alkali disease?
CHRONIC Se poisoning caused by intake of Se accumulator plants or alkaline soil; leads to lameness, loss of hair, hoof malformations, and emaciation
What can cats develop as a result of too much Se and how does this happen?
Hyperthyroidism; canned cat foods often contain 20x Se requirement
(Canned foods also high in iodine)
