Minerals II for BDS

7/31/2019 Minerals II for BDS

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Topic : MINERALS AND TRACE

ELEMENTS-II


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Importance of trace elements, theirdeficiency and biochemical function

Iron uptake, transport, storage and

utilization; iron deficiency and iron overloadstatus.

Role of fluoride

Objectives


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IRON

ZINC

COPPER

IODINE

SELENIUM

FLUORIDE

Minerals are classified as micro minerals or trace minerals ifthe requirement is less than 100 mg.


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Iron is present in almost all cellsIron is an essential component of hemecontaining proteins.

Heme containing proteins:HemoglobinMyoglobinCytochrome P450

CatalaseTryptophan pyrrolase

Iron


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Sources of Iron

Leafy vegetables, Pulses, Liver, Meat

Jaggery is a good source of iron

Milk is a poor source of iron. (


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Daily Requirements for Iron

An adult - 20mg iron per day

About 1-2mg is absorbed from the diet.

Children between 13-15 years need 20-30 mg/day

Pregnant ladies need about 40mg/day

Transfer of iron and calcium from the mother to thefetus normally occurs during the last trimester ofpregnancy.


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Over view of Iron metabolism


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Iron absorption


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Regulation of Absorption of Iron:

In the ferrous state Fe2+

Doudenum and jejunum are the sites of absorption.

Iron metabolism is unique because hemoestasis is maintained

by regulation at the level of absorption and not by excretion.

When iron stores in the body are depleted, absorption is

enhanced. When adequate quantity of iron is stored, absorption

is decreased. This referred to us mucosal block of regulation

of absorption of iron.


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Regulation of Absorption by 3 mechanisms

1. Dietary regulation: Regulation by mucosal block

2. Stores regulation: As body iron stores fall, the mucosa issignaled to increase in absorption.

3. Erythropoietic regulation: In response to anemia, the

erythroid cells will signal the mucosa to increase iron

absorption.

4. Storage : The absorbed iron binds with apoferritin, to form

ferritin, it is kept temporarily in the mucosal cell. If there is

anemia, the iron is further absorbed in the blood stream.

5. Excretion : Iron is lost when cells are desquamated.


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Factors influencing Iron absorption

1. Reduced iron: Only Fe++ (ferrous) form is absorbed.Fe+++ (ferric) form is not absorbed

2. Ascorbic acid: Ferric ions are reduced with the help

of gastric HCL, ascorbic acid, cysteine andSHgroups of proteins. Therefore these will favor iron

absorption.

3. Interfering substances: Iron absorption is decreased

by phytic acid (cereals) and oxalic acid (leafy

vegetables) by forming insoluble iron salts.

4. Other minerals: Calcium, copper, zinc, lead and

phosphates will inhibit iron absorption.


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Storage of iron

Iron is stored in the liver, spleen and bone marrow.

Storage iron occurs in two forms:1. Ferritin: Intestinal mucosal cells, liver, spleen and bone marrow.

2. Hemosiderrin

Iron conservation:

- When RBC lysed Hb enters circulation , being a small molecular

weight substance and will be lost in urine , to prevent loss , this is

immediately taken up by haptogloblin (Hp)


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Iron Transport in the Blood

Transport form of iron in blood is transferrin. Synthesizedby liver cells.

It is a glycoprotein, a b1 globulin with a molecular weight of76,500

One molecule of transferrin can bind to 2 ferric ions

Normal plasma levels are 250 mg/100ml.

Total iron binding capacity (TIBC) of the plasma is about400mg/100ml


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Excretion of iron

Regulation of iron homeostasis occurs at the level

of absorption.

Pathologically iron can be lost during any form of

bleeding.

Menstrual flow is the major cause of loss of iron in

women.

Iron is mainly lost during the desquamation of

intestinal and epithelial cells.


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Clinical Significance

Iron deficiency: Most common nutritionaldeficiency

Iron toxicity: >50mg iron per dayHemosiderosisHemochromatosis


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Iron deficiencyMaternal anemia contributes to the increase in perinatalmortality.

In children anemia often leads to impaired learning ability.

In adults anemia leads to impaired work capacity.


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Causes for Iron Deficiency Hookworm infection: It can be caused where sanitation is poor.

1 hookworm can cause 0.3 ml of loss of blood, 300 worms cancause a loss of 1% of total iron per body.

Nutritional iron deficiency

Repeated pregnancy

About 1 g of iron is lost from the mother during one delivery

Chronic blood loss: Bleeding hemorrhoids (piles), peptic ulcer,

uterine hemorrhage Nephrosis

Kidney glomerular mechanism is inefficient,

Lack of absorption: Subtotal gastrectomy achlorhydria

Lead poisoning: Lead and iron oppose each other. In leadtoxicity, iron absorption and Hb synthesis are reduced. Irondeficiency causes more lead absorption. It is a vicious cycle.

Cli i l F t


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Clinical Features:

Mostly occurs in women

* erythrocytes will be hypochromatic and microcytic and may bedecreased in number

* tiredness, weakness and malaise

* possible increased respiratory rate

* tissue pallor

* bald tongue, atrophic mucositis (mucosal inflammation) , angularcheilitis (inflammatory lesion at the corner of the mouth)

I T i i


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Iron Toxicity

More than 50mg of iron intake maycause nausea, diarrhea and abdominalpain. Unabsorbed iron generate freeradicals, leads to oxidative stress,Hence iron tablets always given alongwith Vitamin C ( to convert to ferrousform) and vitamin E ( to prevent freeradicals).

Iron excess is called as hemosiderosis. Hemosiderin pigments are golden

brown granules seen in the spleen andin the liver. They are complexaggregates of partially denaturedferritin containing 25% iron.Hemosederosis occurs in personsreceiving blood transfusions


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Total body iron is higher than 25-30gm, hemosiderosis is

manifested.

In liver hemosiderin deposits leads to cells of death and

cirrhosis.

Pancreatic cell death leads to diabetes.

Deposits under the skin can cause yellow-brown

discoloration, which is called hemochromatosis.

The triad of cirrhosis, hemochromatosis and diabetesare referred to as bronze diabetes.


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Hemochromatosis

Cirrhosis Diabetes

Bronzediabetes

A liver with hemochromatosis Iron

staining: blue granules of

hemosiderin


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Zinc

Functions of zinc:

1. Zinc is a constituent of a number of enzymes.

[carbonic anhydrase, DNA and RNA polymerase]

2. Zinc is necessary for the normal growth.

3. Zinc is involved in wound healing.

4. Zinc is included in the native structure of insulin


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Rich sources of dietary zinc include meat, poultry, fish, nuts, seeds,legumes and whole grain cereals.

However, zinc from animal sources has higher bioavailability than plant

sources. Plant sources contain fibre and phytate that inhibit zinc uptake by

the intestine.

Oysters are good sources of zinc


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Copper

It is a metal co-factor for various enzymes.

1. Cytochrome C oxidase[terminal enzyme of mitochondrial electrontransport]

2. Superoxide dismutase[anti oxidant defence]- oxidative damage

3. Ceruloplasmin ferroxidase involved in ironabsorption]

4. Tyrosinase [synthesis of melanin]


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Rich sources of copper: oysters, beef or lamb liver, Brazil nuts,blackstrap molasses, cocoa, and black pepper.

Good sources: lobster, nuts and sunflower seeds, green olives,

and wheat bran.

SOURCES OF COPPER
http://upload.wikimedia.org/wikipedia/commons/e/e1/ARS_copper_rich_foods.jpg


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DisorderWilsons disease

Wilsons disease --- inborn error of copper metabolism-

Hepatic and neurologic dysfunction.

Hepatolenticular degeneration disease : deposition of

copper in brain, liver and cornea and red blood cells.

Gene encoding copper binding ATPase is defective.

Inability to excrete copper into bile

Accumulation of copper in liver

and later in the brain (lenticular

nucleus) and other tissues (RBCs). Cirrhosis, tremor, ataxia.


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Clinical features:1.Chronic liver disease --- Eventually leads to cirrhosis andhepatic failure.

2.Neurological syndrome . Accumulation of copper in

basal ganglia

3. Hemolytic anemia

4.Keyser-Fleischer Ring (KF Ring) deposition of copperin the Descemets membrane of the cornea


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Iodine

Iodine is the raw material essential for thyroid hormone

synthesis, growth and development

Source: iodinated salt, drinking water.

The principle organs that take up iodine are:

Thyroid: thyroid hormone synthesis- Thyroid hormonesare essential as they regulate protein synthesis and enzyme

activities in muscles, brain, heart, kidney and pituitary gland.

Kidney: excretes excess in the urine.


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Sources

Iodine is found in variable amounts infoods and drinking water.

Foods such as clams, fish, crab, prawn,cuttlefish, oysters and other saltwater

fish are the richest source of iodine.

A wide variety of food also containsiodine such as eggs, meat, milk and milk

products, cereal grains and dried fruits.Choose iodine containing foods as partof your healthy diet.

Hypothyroidism: Both iodine deficiency and inability to use iodine


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Hypothyroidism: Both iodine deficiency and inability to use iodineproperly make the thyroid gland unable to produce thyroid hormone, ahormone that helps to regulate the bodys metabolic rate. This state iscalled hypothyroidism and the symptoms include swelling of the nodulesin the thyroid gland, fatigue, weight gain, heavy menstrual bleeding inwomen, dry skin and hair, as well as goiter.

Causes for goiter

Dietary deficiency

Where soil content and water content of iodine is less. Iodine-

deficiency goiter can be common in regions where the soils and foodshave insufficient iodine

Presence of Goiterogens in diet

Vegetables of the Brassicaceae family eg. Cabbages, spinach, turnipsetc.

Anti-thyroid drugs Perchlorate and thiocyanates prevent iodine uptake by the thyroid


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Cretinism:

Children who are iodine deficient from birth (if

the mother is iodine deficient) develop childhoodhypothyroidism and are called cretins.

They are dwarfed, mentally retarded and have

potbellies and enlarged, protruding tongues.A visible swelling at the base of your neck

A tight feeling in your throat

Coughing

HoarsenessDifficulty swallowing

Difficulty breathing
http://baleru.com/picture-of-goiter-patient.html


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Selenium

Requirement: 50-100 microgram/day.

Sources:Drinking water, brazil nuts, garlic,crops grown on soil rich in

selenium seafood is a good source.Functions:

1.Selenium is a constituent of glutathione

peroxidase [antioxidant]2. It is also constituent of iodothyronine deiodinase


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Fl id


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Fluoride

Sources: Good source is drinking water

Moderate source : fish, egg, cheese and tea.

Requirement: 1mg/L (1ppm) of drinking

water.
http://en.wikipedia.org/wiki/File:USDA_Mineral_Flourite_93c3962.jpg


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Fluoride is known to prevent dental caries.

Bacteria present in the oral cavity degrade food

particles in the grooves and crevices of teeth toproduce organic acids.

These organic acids are responsible for tooth decay.

Fluorine forms a layer of fluroapatite over the enamel

which prevents exposure of enamel to these harmful

organic acids.

For remineralization of decalcified teeth

Required for normal mineralization of bone.

GOALS OF FLUORIDE (F) ADMINISTRATION


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GOALS OF FLUORIDE (F) ADMINISTRATION

Do no harm

Prevent decay on in tact

dental surfaces

F

F

Arrest active decay

Remineralize

decalcified teeth

1.

2.

3.

4.

F

Fluorosis or

toxicity


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Fluro apatite crystals

Action of fluoride

Formation of fluroapatite

crystalsresistant to

bacterial action

Catalyst for deposition of

calcium and phosphate-

remineralisation of damaged

enamel and combating decay


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RECOMMENDATIONS FOR THE USE OF FLUORIDE

TOOTHPASTE IN CHILDREN BELOW 6 YEARS OF AGE

Only a pea-sized amount of fluoride toothpaste (5 mm)

should be applied to the bristles. A pea size of a 1000 ppm

fluoridated toothpaste, delivers not more than 0.1mg fluoride.

Parents / minders should still supervise toothbrushing

activity of their 6-year-olds or younger children even if theyare capable of brushing their own teeth.

Children should be taught to spit out and to rinse thoroughly

with water after toothbrushing. This is to prevent swallowing

of toothpaste

FLUORIDE DENTIFRICE, Dr. Zubaidah Ahmad

Malaysian Dental association.

FLUOROSIS


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moderate

severe

mild

pitting


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List the important trace elements, their deficiency

and biochemical function.

Discuss iron uptake, transport, storage and

utilization; iron deficiency and iron overload status.

Biological importance of fluoride, flurosis

Learningoutcomes

Minerals II for BDS

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