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Biochemistry research 1


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Biochemistry research 1

  2. 2. INTRODUCTION : - A lot of people dont take the risks of high cholesterol very seriously.Cholesterol is a direct contributor to cardiovascular disease, which can lead to strokes and heart attacks. - The World Health Organization estimates that almost 20% of all strokes and over 50% of all heart attacks can be linked to high cholesterol. - Cholesterol is a fat-like substance circulating in your blood. Some of your cholesterol comes from the foods you eat. But the bulk of it is actually made in your own body, specifically in the liver. Cholesterol does have some good uses. It is needed to make some hormones and it is important for the function of our cells. But an excess of it in the bloodstream can lead to trouble.LIPOPROTEINS :DEFINITION :Lipoproteins are a combination of lipids and proteins. Lipids are fatty substances thatare insoluble in water. Proteins, which are made of amino acid building blocks, arebonded directly to the lipids. Lipoproteins are synthesized in the liver, which is one ofthe main metabolic arenas for fatty substances such as cholesterol.STRUCTUER : - Lipoproteins are macromolecular structures (supramolecular complexes) formed by the association of proteins and lipids, whose main function is to facilitate the transport of lipids (apolar compounds) in the aqueous environment (polar) that is blood. - We can distinguish in a lipoprotein an envelope and the core. The envelope is 2
  3. 3. formed mainly by amphipatic lipids of the kind of phospholipids, like lecithins, cephalins and others. These phospholipids have their polar part oriented to the aqueous surface, while the apolar part interacts with the hydrophobic core of the lipoprotein, formed mainly by cholesterol esters and triacylglycerols. - Free Cholesterol also appears forming part of the lipoprotein envelope, with the Carbon 3 hydroxyl oriented to the polar environment, and the apolar rest of the molecule embedded in the hydrophobic portion of the monolayer formed by the phospholipids. - The proteins that form these structures are called apoproteins (like all proteinic part of conjugated proteins). The hydrophilic amino acids of these apoproteins are oriented to the outside, while the hydrophobic amino acids interact with the apolar part of the lipoprotein structure.FUNCTIONS : - The function of lipoprotein particles is to transport lipids (fats) (such as triacylglycerol) around the body in the blood - All cells use and rely on fats and cholesterol as building-blocks to create the multiple membranes that cells use both to control internal water content and internal water-soluble elements and to organize their internal structure and protein enzymatic systems - The lipoprotein particles have hydrophilic groups of phospholipids, cholesterol, and apoproteins directed outward. Such characteristics make them soluble in the salt water-based blood pool. Triglyceride-fats and cholesterol esters are carried internally, shielded from the water by the phospholipid monolayer and the apoproteins 3
  4. 4. - The interaction of the proteins forming the surface of the particles (a) with enzymes inthe blood, (b) with each other, and (c) with specific proteins on the surfaces of cellsdetermine whether triglycerides and cholesterol will be added to or removed from thelipoprotein transport particlesCLASSIFICATIONS : 1- By density :Lipoproteins may be classified as follows, listed from larger and less dense to smallerand denser. Lipoproteins are larger and less dense, if they consist of more fat than ofprotein. They are classified on the basis of electrophoresis and ultracentrifugation- Chylomicrons :carry triglycerides (fat) from the intestines to the liver, to skeletal muscle, and toadipose tissue.- Very-low-density lipoproteins (VLDL) :carry (newly synthesised) triacylglycerol from the liver to adipose tissue- Intermediate-density lipoproteins (IDL) :are intermediate between VLDL and LDL. They are not usually detectable in the blood- Low-density lipoproteins (LDL) :carry cholesterol from the liver to cells of the body. LDLs are sometimes referred to asthe "bad cholesterol" lipoprotein When too much LDL (bad) cholesterol circulates in theblood, it can slowly build up in the inner walls of the arteries that feed the heart andbrain. Together with other substances, it can form plaque, a thick, hard deposit thatcan narrow the arteries and make them less flexible. This condition is knownas atherosclerosis. If a clot forms and blocks a narrowed artery, heart attack or strokecan result. 4
  5. 5. - High-density lipoproteins (HDL) :collect cholesterol from the bodys tissues, and bring it back to the liver. About one-fourth to one-third of blood cholesterol is carried by high-density lipoprotein (HDL). HDLcholesterol is known as "good" cholesterol, because high levels of HDL seem to protectagainst heart attack. Low levels of HDL (less than 40 mg/dL) also increase the risk ofheart disease. Medical experts think that HDL tends to carry cholesterol away from thearteries and back to the liver, where its passed from the body. Some experts believethat HDL removes excess cholesterol from arterial plaque, slowing its buildup.Lipoprotein Density Protein Lipids Predominant Lipid (% total % total (% of total weight) weight) weight)Chylomicrons <1.006 2 98 Triacylglycerol (85 %)VLDL 0.950-1.006 10 90 Triacylglycerol (50%)IDL 1.006-1.019 12 88 About 40 % Cholesterol (30 % esterified and 10 % free)LDL 1.019-1.063 25 75 About 50 % Cholesterol (40 % esterified + 10% free)HDL 1.063-1.210 55 45 Phospholipids (35 %) 2- Alpha and Beta : - It is also possible to classify lipoproteins as "alpha" and "beta", according to the classification of proteins in serum protein electrophoresis. This terminology is sometimes used in describing lipid disorders such as Abetalipoproteinemia 3- Lipoprotein(a) : - Lipoprotein(a) – Lp(a), Cardiology diagnostic tests < 14 mg/dL : Normal 14-19 mg/dL : ? > 19 mg/dL : High risk 5
  6. 6. ADVANTAGES and DISADVANTAGES : - Advantages : 1- Cholesterol is a hard substance that is used in the membranes of each cell in the body. It gives the cell strength and rigidity. 2- Increase vitamin D. Vitamin D is used in the immune system and can help to regulate blood pressure. If a person is in the sun, the sunlight will convert cholesterol to vitamin D. 3- Cholesterol acts as a transport for various antioxidant vitamins and enzymes, particularly vitamin A and E. 4- Skin Protection. The waxy substance acts as a protective layer against sun and wind damage. It has been found in higher than normal levels in scar tissue suggesting that it is involved in the healing process. - Disadvantages : 1- Cholesterol is not soluble in the blood so it has to be transported by attaching to lipoproteins in the blood. The two important types of lipoproteins are known as low density and high density lipoproteins. 2- when there is too much (LDL) Low density lipoproteins cholesterol it tends to stick to the artery walls. This is know as thickening arteries or athersclerosis. Atherosclerosis can cause high blood pressure as the volume of the arteries is decreased. It can lead to blood clots if there are blockages in the arteries. This can lead to a stroke. Ultimately, too much cholesterol leads to heart disease. 6
  7. 7. GRAPHES : Effect of Fats on Blood Cholesterol LevelsHigh blood serum cholesterol levels are associated with increased risk of cardiovasculardiseases. Research on dietary fats by Hegsted and others has shown that myristic acid(C14:0), and palmitic acid (C16:0) increase cholesterol levels, whereas polyunsaturatedfats such as linoleic acid (C18:2) reduce cholesterol levels. Effect of fatty acids on blood cholesterol[23]The chart above shows the effects of individual dietary fatty acids on Total SerumCholesterol, LDL cholesterol, and HDL cholesterol when l% of the energy fromcarbohydrates in the diet is replaced by 1% of energy of the specific fatty acids. Thechart shows cholesterol increases from lauric acid (C12:0), myristic acid (C14:0),and palmitic acid (C16:0) which are found in coconut oil, palm oil, and butter. Elaidicacid (trans-C18:1), which is present in hydrogenated fats, is the worst because itincreases LDL and decreases HDL. The saturated fatty acid stearic acid (C18:0), themonounsaturated oleic acid (C18:1), and the polyunsaturated linoleic acid (C18:2)decrease LDL and increase HDL to various degrees.[23] 7
  8. 8. WHAT IS ARTHEROSCLEROSIS ? - Atherosclerosis is a disease in which plaque builds up inside your arteries. Arteries are blood vessels that carry oxygen-rich blood to your heart and other parts of your body - Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. Over time, plaque hardens and narrows your arteries. This limits the flow of oxygen-rich blood to your organs and other parts of your body - Atherosclerosis can lead to serious problems, including heart attack, stroke, or even deathFigure A shows a normal artery with normal blood flow. Figure B shows an artery withplaque buildup 8
  9. 9. ARTHEROSCLEROSIS RELATED DISEASES :Atherosclerosis can affect any artery in the body, including arteries in the heart, brain,arms, legs, pelvis, and kidneys. As a result, different diseases may develop based onwhich arteries are affectedCoronary Heart Disease - Coronary heart disease (CHD) occurs if plaque builds up in the coronary arteries. These arteries supply oxygen-rich blood to your heart - Plaque narrows the coronary arteries and reduces blood flow to your heart muscle. - If blood flow to your heart muscle is reduced or blocked, you may have angina (chest pain or discomfort) or a heart attackCarotid Artery Disease - Carotid artery disease occurs if plaque builds up in the arteries on each side of your neck (the carotid arteries). These arteries supply oxygen-rich blood to your brain. If blood flow to your brain is reduced or blocked, you may have a stroke.Peripheral Arterial DiseasePeripheral arterial disease (P.A.D.) occurs if plaque builds up in the major arteries thatsupply oxygen-rich blood to your legs, arms, and pelvisIf blood flow to these parts of your body is reduced or blocked, you may havenumbness, pain, and, sometimes, dangerous infectionsChronic Kidney DiseaseChronic kidney disease can occur if plaque builds up in the renal arteries. These arteriessupply oxygen-rich blood to your kidneys Over time, chronic kidney disease causes aslow loss of kidney function. 9
  10. 10. TREATMENT OF ARTHEROSCLEROSIS :Cholesterol Medications: Aggressively lowering your low-density lipoprotein (LDL) cholesterol, the "bad"cholesterol, can slow, stop or even reverse the buildup of fatty deposits in your arteries.Boosting your high-density lipoprotein (HDL) cholesterol, the "good" cholesterol, mayhelp, too. The doctor can choose from a range of cholesterol medications, includingdrugs known as statins and fibratesAnti-platelet medications:The doctor may prescribe anti-platelet medications, such as aspirin, to reduce thelikelihood that platelets will clump in narrowed arteries, form a blood clot and causefurther blockageBeta blocker medications:These medications are commonly used for coronary artery disease. They lower yourheart rate and blood pressure, reducing the demand on your heart and often relievesymptoms of chest pain. Beta blockers reduce the risk of heart attacks and heartrhythm problemsAngiotensin-converting enzyme (ACE) inhibitors:These medications can help slow the progression of atherosclerosis by lowering bloodpressure and producing other beneficial effects on the heart arteries. ACE inhibitors canalso reduce the risk of recurrent heart attacksCalcium channel blockers :These medications lower blood pressure and are sometimes used to treat angina 10
  11. 11. Water pills (diuretics):High blood pressure is a major risk factor for atherosclerosis. Diuretics lower bloodpressureOther medications: - Endarterectomy: In some cases, fatty deposits must be surgically removed from the walls of a narrowed artery. When the procedure is done on arteries in the neck (the carotid arteries), its known as carotid endarterectomy - Thrombolytic therapy: If you have an artery thats blocked by a blood clot, your doctor may insert a clot-dissolving drug into your artery at the point of the clot to break it up - Bypass surgery: Your doctor may create a graft bypass using a vessel from another part of your body or a tube made of synthetic fabric. This allows blood to flow around the blocked or narrowed artery. 11
  12. 12. HOW TO PROTECT YOUR HEART ?1-Limit how much saturated and trans fats you eat that contribute to a buildup ofplaque in your arteries2 -Choose from sources of low-fat proteins3-More fruits and vegetables4 -Select whole grains5- Reduce salt intake -Eat in moderation7-Create daily menus and plan 12
  13. 13. MADE BY SECTION (2) STUDENTS : 1- Jehan Essam Mahmoud (112 ) 2- Aya Ahmed Saber Yosif (86) 3- Eman Mohammed Mustafa (83) 4- Gehad Abdelaziz Salem (106) 13