Lecture 2: Carbohydrates, Lipids, Proteins, Vitamins, and Minerals, Health Maintenance PDF

The assessment of carbohydrates, lipids, proteins, vitamins and minerals, and health maintenance Pixabay.com 1. Carbohydrates Importance Functions: Molecular recognition Structural materials Classification: Monosaccharides Oligosacchari...

The assessment of carbohydrates, lipids, proteins, vitamins and minerals, and health maintenance Pixabay.com 1. Carbohydrates Importance Functions: Molecular recognition Structural materials Classification: Monosaccharides Oligosaccharides Polysaccharides Metabolism 1. Carbohydrates Clinical Importance Hormonal control: insulin and glucagon Hypoglycemia Hyperglycemia Pixabay.com Laboratory considerations Blood glucose concentration measurement Screening, diagnosis, and monitoring Diagnostic criteria (Diabetes Canada and ADA)  2. Lipids Essential to the human body Clinical significance (dyslipidemias) Properties Wikimedia Commons, 2024 Insoluble in water Soluble in organic solvents Clinically significant classes of lipids: Fatty acids, triglycerides, phospholipids, cholesterol, sphingolipids, fat-soluble vitamins 2.1 Fatty acids Essential to the human body Most come from our diet Functions Clinical significance: Excess starvation or uncontrolled diabetes https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistr y_%28CK-12%29/26%3A_Biochemistry/26.08%3A_Triglycerides mellitus Ketone bodies: acetoacetic acid, beta- hydroxybutyric acid, acetone Ketosis and ketoacidosis 2.2 Triglycerides Most prevalent fat in the diet Effectively transport fatty acids Excess carbohydrates are stored as triglycerides Low glucose= breakdown of triglycerides Excess fatty acids in blood Transported in lipoproteins Clinical significance: Increased in certain diseases/conditions https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_%28 CK-12%29/26%3A_Biochemistry/26.08%3A_Triglycerides Decreased in hyperthyroidism 2.3 Phospholipids “Similar” to triglycerides Mostly synthesized in the liver Functions: Cell membrane structural units https://www.thoughtco.com/phospholipids-373561 Mitochondrial metabolism Blood coagulation Lipid transport Clinical significance Act as lung surfactant https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/27%3A_Biomolecules_- _Lipids/27.03%3A_Phospholipids 2.4 Cholesterol Most cholesterol is synthesized in the liver Functions Component of cell membrane Precursor for steroid hormones, vitamin D and bile acids https://en.wikipedia.org/wiki/Cholesterol Transported in lipoproteins Clinical significance (increased concentrations): Hyperlipidemia Atherosclerosis Liver disease 2.5 Other lipids Sphingolipids Pixabay.com Fat-soluble vitamins (A, D, E and K) Clinical significance: Disorders in sphingolipid catabolism E.g. Gautcher’s disease https://pixorize.com/view/6886 3. Lipoproteins Spherical complexes Transport insoluble fat through the blood Clinical significance Cardiovascular disease Atherosclerosis Laboratory consideration Importance of measurements Classification 3. Lipoproteins (classification) Five main classes of lipoproteins: Chylomicrons – Largest, least dense (small intestine) Very low-density lipoprotein (VLDL)- synthesized in the liver Intermediate-density lipoproteins (IDL)- formed when triglycerides is removed from VLDL, rich in cholesterol Low-density lipoprotein (LDL)- cholesterol rich, carry cholesterol in the plasma High-density lipoprotein (HDL)- the smallest and densest lipoproteins, reverse cholesterol transport  3.1 Apolipoproteins Functions *Lp (a) – independent risk factor for cardiovascular disease  3.2 Lipoprotein metabolism 1. The exogenous lipid cycle 2. The endogenous lipid cycle Enzymes involved in lipoprotein metabolism: Lipoprotein lipase (LPL) Lecithin-cholesterol acyltransferase (LCAT) forms cholesteryl esters from free cholesterol and fatty acids ❖ The exogenous lipid cycle Begins after fat is ingested Absorbed in small intestine- chylomicrons Chylomicrons reach the bloodstream Triglycerides are removed by LPL Chylomicrons become smaller (removed) Cholesterol is processed by the liver Liver (only route to excrete cholesterol) ❖ The endogenous lipid cycle Liver synthesizes triglycerides and cholesterol VLDL particles formed LPL hydrolyses VLDL molecules An intermediate-density lipoprotein (IDL) forms IDL becomes LDL LDL delivers cholesterol through high-affinity LDL receptor Other scavenger routes – high levels of LDL ✓HDL returns cholesterol to the liver ✓Antiatherogenic process 4. Lipids and laboratory results Preanalytical factors: Diet/lifestyle Acute illness Plasma (serum) appearance “Creamy layer floating” Ideally same day testing Wikimedia Commons, 2024 Lipid panels (serum): total cholesterol, VLDL, LDL, HDL, triglyceride level (fasting!) https://www.mm3admin.co.za/cms/cpd/articles/f849a651-157e-4dc4-b9d9-9e29ce73aa6b.pdf Test results and interpretation Strategy: total cholesterol and HDL for case finding  5. Proteins Composition Functions E.g., Energy production, oncotic pressure, transport Levels of structure Primary Secondary Tertiary Quaternary https://ib.bioninja.com.au/standard-level/t opic-2-molecular-biology/24-proteins/amino-acids.html 5. Proteins Protein denaturation Change in secondary, tertiary, or quaternary structure Acids, detergent, heat, etc. can denature proteins Acid in the stomach Precipitation or coagulation Irreversible process https://chem.libretexts.org/Courses/American_River_College/CHEM_309%3A_A pplied_Chemistry_for_the_Health_Sciences/09%3A_Proteins_-_An_Introduction/9.0 6%3A_Denaturation_of_Proteins#:~:text=Denaturation%20is%20the%20term%20u sed,%2C%20tertiary%2C%20or%20quaternary%20structure.  5.1 Classification of proteins Simple proteins Globular (albumin, globulins, histones, and protamines) Fibrous (collagens, elastins, and keratins) https://depositphotos.com/photos/protein-structure.html Resistant to proteolytic enzymes Conjugated proteins Glycoproteins, lipoproteins, metalloproteins, etc. 5.2 Properties of proteins allow for differentiation Separation based on: Molecular size Solubility Electrical charge Specific binding to antibodies https://www.bio-rad.com/en-ca/applications-technologies/protein-electrophoresis-methods?ID=LUSOW4GRI 5.3 Plasma proteins Serum proteins: Albumin ”Other proteins” (globulins) Individual plasma protein concentration can be affected Total protein levels remain relatively constant https://my.clevelandclinic.org/health/body/22865-plasma Assess of protein nutrition – albumin measurements Most plasma proteins are synthesized in the liver Importance of plasma protein analyses 5.4 Clinical significance of common plasma proteins 1. Albumin Major plasma protein Also found in CSF, interstitial fluid, urine and amniotic fluid Synthesized in the liver Major contributor to plasma oncotic pressure Functions Maintain oncotic pressure in the intra and extravascular spaces Transport molecules 5.4 Clinical significance of common plasma proteins 1. Albumin (Cont.) Clinical importance Increased levels Decreased levels (hypoalbuminemia) Inflammation, liver disease, malabsorption, abnormal degradation, etc. Measurements not useful to monitor long-term nutritional support 5.4 Clinical significance of common plasma proteins 2. Myoglobin Small protein that stores oxygen Makes up the skeletal muscle Related to hemoglobin Functions Clinical importance https://www.docsity.com/en/myoglobin-and-hemoglobin-molec ular-biology-and-biochemistry-bch-4024/6921835/ Released into the blood after damage of tissue High concentration - acute renal failure Laboratory consideration: Myoglobin quantification 5.4 Clinical significance of common plasma proteins 3. Hemoglobin Complex structure Functions Transports oxygen and carbon dioxide Clinical importance Iron deficiency Anemia Hemoglobinopathies Laboratory consideration: plasma-free hemoglobin 5.4 Clinical significance of common plasma proteins 4. Immunoglobulins Or antibodies Produced by…. Five classes: IgG, IgM, IgA, IgD , and IgE Functions Proteins that work as antibodies 5.4 Clinical significance of common plasma proteins 4. Immunoglobulins (cont.) Laboratory considerations The use of electrophoresis Immunofixation Clinical importance Increased immunoglobulins: Polyclonal hyperimmunoglobulinemias Monoclonal immunoglobulinemia (paraprotein) – multiple myeloma (Bence-Jones proteins) Immunoglobulin deficiency or absence 5.4 Clinical significance of common plasma proteins 5. Coagulation factors Hepatocytes are the main producers Clotting factors XIII, XII, XI, X, IX, VII, V, II, and I. Functions https://www.cusabio.com/c-16412.html#a02 Hemostasis Tests: Clinical importance Prothrombin time (PT) Liver disease Activated partial thromboplastin time (APTT) 5.5 Proteins in other body fluids Urinary protein Tamm-Horsfall protein (40 mg/24 hours) Large quantities of albumin (e.g. diabetes) Microalbumin test (urine dipstick method) https://www.mountsinai.org/health-library/tests/cerebral-spinal-fluid-csf-collection Cerebral spinal fluid (CSF) protein Around 95% of CSF proteins enter the CNS through blood-brain barrier Clinical significance of large amounts of proteins in the CSF Spinal tap 5.6 Roles of proteins X enzymes Proteins Enzymes Large, multiunit Biological catalysts molecules Conversion of Transport substrate molecules to Receptors products Catalysts Involved in specific Structure and essential reactions https://www.123rf.com/photo_12771380_enzyme-pepsin-3d-model.html Nutritional Most are proteins 6. Vitamins Micronutrients Classification: Water-soluble Fat-soluble Importance Murphy et al. 2019 Clinical Biochemistry Mostly intracellular action How can a patient have deficiency of vitamins? 7. Trace elements Inorganic elements Small amounts ppm Trace element deficiency Toxicity is rare Mostly intracellular action Murphy et al. 2019 Clinical Biochemistry Laboratory considerations Assessment (contamination) 7. Trace elements Clinically significant trace elements Zinc Iodine Copper Selenium Iron Murphy et al. 2019 Clinical Biochemistry 8. Nutritional assessment Malnutrition Protein (serum albumin) Evaluation History Blood glucose concentration Examination (e.g., BMI) Laboratory investigations Lipids Vitamins Major minerals Trace elements Pixabay.com 9. Nutritional support Nutritional support Patients may be fed in the following ways: ▪ oral feeding ▪ enteral ▪ parenteral Murphy et al. 2019 Clinical Biochemistry Importance of clinical and biochemical monitoring 9.1 Parenteral nutrition Total parenteral nutrition (TPN) Components of TPN Monitoring patients on TPN Complications – e.g. hyperglycemia 10. Tumour markers The use of tumour markers Definition Targeted screening, diagnosis and monitoring Types of tumour markers: Enzymes (e.g., PSA, alkaline phosphatase) Hormones (e.g,. HCG, human chorionic gonadotrophin) Carbohydrates (e.g.,CA 125, CA 19-9) Oncofetal antigens (e.g., AFP, CEA) 10. Tumour markers Enzymes PSA (screening of general population) Alkaline phosphatase Neuron-specific enolase 10. Tumour markers Hormones ACTH (pituitary gland?) Calcitonin Beta-hCG 10. Tumour markers Carbohydrates Mucins CA 15-3 CA 27.29 CA 125 Blood group antigens CA 19-9 (diagnostic) 10. Tumour markers Oncofetal antigens Alpha-Fetoprotein (AFP) Carcinoembryonic antigen CEA: 3 ug/L (CEA)- pancreatic, lung, breast for healthy and gastrointestinal cancer adult nonsmokers and 5 ug/L for smokers