CC1 PART 2

*No Tables

• Number of sugar units

• Number of carbons

• Location of the CO group

• Stereochemistry

CLASSIFICATION OF CARBOHYDRATES

Number of sugar units

CLASSIFICATION OF CARBOHYDRATES:

polysaccharides, disaccharides, monosaccharide

Number of carbons

CLASSIFICATION OF CARBOHYDRATES:

trioses, tetroses, pentoses, hexoses

Location of the CO group

CLASSIFICATION OF CARBOHYDRATES:

aldoses and ketoses

Stereochemistry

CLASSIFICATION OF CARBOHYDRATES:

D and L enantiomers

D enantiomers

• also known as “dextrorotatory”

• OH is on the Right

  
  

These are examples of:

• D-glyceraldehyde

• D-Erythrose

• D-Glucose

• Galactose

L enantiomers

• also known as “Levorotatory”

• OH is on the Left

  
  

These are examples of:

• L - Ribose

• Form glycosidic bonds with other carbohydrates and with noncarbohydrates

• Modify proteins and their function by glycosylation

• Some are reducing substances (sugars with hemiacetal group)

GENERAL PROPERTIES OF CARBOHYDRATES

Sucrose

• Some are reducing substances (sugars with hemiacetal group)

  • One of its most notable exception is ______ which has no hemiacetal group (therefore does not interfere)

1. Glycolysis

2. Gluconeogenesis

3. Glycogenesis

4. Glycogenolysis

5. Lipogenesis

6. Lipolysis

7. TCA Cycle

EXAMPLES OF METABOLIC PATHWAYS

Glycolysis

• metabolism of glucose to pyruvate or lactate for production of energy; occurs in the Cytoplasm of Cells

  • Energy yield - ATPs produced = 2 (net)

  • Irreversible steps

• All arrow going up (yellow highlight)

Irreversible steps

All violet boxes are ______

Gluconeogenesis

• de novo synthesis of glucose from noncarbohydrate sources; occurs in the primarily in the Cytoplasm of cells, primarily in the Liver & Kidneys

• All arrow going down (blue highlight)

Glycogenesis

• conversion of glucose to glycogen, primarily in the liver and muscle

Glycogenolysis

• breakdown of glycogen to glucose

• Reverse Gluconeogenesis

Lipogenesis

• Happens in the adipose tissue

• conversion of carbohydrates to lipids primarily fatty acidsand triglycerides

Lipolysis

• breakdown of triglycerides into glycerol and fatty acids

TCA Cycle

• oxidation of acetyl CoA derived from the breakdown of carbohydrates (glycolysis), fatty acids, and certain amino acids; occurs in the Mitochondria

• also known as “Krebs Cycle”

• Hypoglycemic Disorders

• Diabetes Mellitus

DISORDERS OF GLUCOSE METABOLISM

Post-absorptive/Fasting

UNDER HYPOGLYCEMIC DISORDERS TYPES:

• occurs after 10 hours without food; secondary to hyperinsulinism (insulinoma), hormonal deficiencies, genetic disorders, autoimmunity or drug-induced

• Pancreatic tumor that hyper secretes insulin

Post-prandial/Alimentary/Reactive

UNDER HYPOGLYCEMIC DISORDERS TYPES:

• occurs usually within 4 hours after eating a meal

Neurogenic

UNDER HYPOGLYCEMIC DISORDERS SYMPTOMS:

• tremulousness, palpitations, anxiety, diaphoresis, hunger, and paresthesias

• Related to ANS

• Predominate in Reactive hypoglycemia or in the autonomic nervous systems

Neuroglycopenic

UNDER HYPOGLYCEMIC DISORDERS SYMPTOMS:

• dizziness, tingling, blurred vision, behavioral changes, seizure, and coma

• Predominate in fasting hypoglycemia or in decreased glucose supply to the brain.

• Panic value: <40 mg/dL

Whipple’s triad of hypoglycemia

UNDER HYPOGLYCEMIC DISORDERS DIAGNOSIS:

• symptoms of hypoglycemia, low plasma glucose level, and relief of symptoms with correction of hypoglycemia

• ≤ 50 mg/dL

• Present in all types of hypoglycemia

↑

UNDER HYPOGLYCEMIC DISORDERS DIAGNOSIS:

• Change in plasma glucose ≥25 mg/dL (under controlled fasting condition) coincident with:

  • __ insulin level (≥41.7 pmol/L)

  • __ proinsulin level (≥5 pmol/L)

  • __ C-peptide level (≥0.2 nmol/L)

↓

UNDER HYPOGLYCEMIC DISORDERS DIAGNOSIS:

• Change in plasma glucose ≥25 mg/dL (under controlled fasting condition) coincident with:

  • __ βHA (β-Hydroxybutyric acid) levels (≤2.7 mmol/L) - ketone

Insulinoma

• Also endogenous hyperinsulinism

  • endogenous − increased proinsulin and C-peptide level

  • exogenous − overdose in insulin

• Most common type of hypoglycemia (#1 cause of fasting)

• “-oma” meaning pancreatic tumor cells that hypersecrete insulin

  • Uncontrollable, does not respond to feedback mechanism

• Insulinoma is the exact opposite of Type 1 DM

Proinsulin

• a precursor of C-peptide and insulin

• Insulin is from proinsulin

  • C peptide needs to be cleaved so that proinsulin becomes insulin

C - peptide

• Marker and indicator of endogenous hyperinsulinism

• Fragment released from proinsulin molecule

β-Hydroxybutyric acid

• major ketone body

  • most abundant ketone (78% of ketone bodies)

• primary marker of DM and insulinoma

  • High in Type 1 DM

  • Low in Insulinoma

Type 1 DM

UNDER DIABETES MELLITUS ADA CLASSIFICATION:

• B Cell destruction leading to absolute insulin deficiency

  • Immune mediated - (+) auto antibodies; about 99% cases

  • idiopathic

• DEFICIENT

Type 2 DM

UNDER DIABETES MELLITUS ADA CLASSIFICATION:

• Insulin resistance with progressive insulin deficiency

• No problem in insulin production; receptor; intracellular defects (no cell response)

• RESISTANT

• Genetic defects of B cell function

• Genetic defects in insulin action

• diseases of the exocrine pancreas

• Endocrinopathies

• Drug-or chemical-induced

• Infections

• Uncommon forms of immune-mediated diabetes

• Other genetic syndromes

UNDER DIABETES MELLITUS ADA CLASSIFICATION:

OTHER TYPES OF DM:

diseases of the exocrine pancreas

These are examples of What Type of DM:

• pancreatitis, pancreatectomy, pancreatic cancer/neoplasia, cystic fibrosis, hemochromatosis, fibrocalculous pancreatopathy

Gestational

UNDER DIABETES MELLITUS ADA CLASSIFICATION:

• glucose intolerance during pregnancy that disappears post-partum but may convert to type 2 DM in 30-40% of cases within 10 years;

• due to metabolic and hormonal changes

Every 3 Years

TESTS AND DIAGNOSTIC CRITERIAFOR DM:

• Screening Tests for Adults ≥ 45 years old

Every Year

TESTS AND DIAGNOSTIC CRITERIAFOR DM:

• Screening Tests for Individuals ≥ 1 risk factor

HbA1C and FPG

TESTS AND DIAGNOSTIC CRITERIAFOR DM:

*In the absence of unequivocal hyperglycemia, diagnosis requires two abnormal test results obtained at the same time (e.g., ________________) or same test at two different time points.

24-28

TESTS AND DIAGNOSTIC CRITERIA FOR GDM:

• All nondiabetic pregnant women should be screened for GDM at _______ weeks of gestation.

Whole Blood Glucose

TESTS FOR MONITORING GLYCEMIC CONTROL:

• Daily Monitoring

• most commonly analyzed using POCT devices at home or at the patient’s bedside; 3-4 times daily for type 1 DM patients according to ADA guidelines

• about 10-15% lower than plasma glucose

• ADA glycemic goals:

  • Pre-prandial (before meal): 70-130 mg/dL

  • Post-prandial (after meal): <180 mg/dL

HBA1C (Glycated Hemoglobin)

TESTS FOR MONITORING GLYCEMIC CONTROL:

• Long Term Monitoring

• Hb A with glucose irreversibly attached to one or both N-terminal valines of the β-chains

• Provides an index of average blood glucose levels over the past 2-3 months

• Unreliable in patients with hemolytic disorders (e.g. hemoglobinopathies, autoimmune hemolytic anemia)

  • ADA glycemic goal: < 7%

  • Poor control: >12%

  • eAG = (28.7*A1c) 46.7

120 Days

• Life span of RBCs

• glycosylation occurs also while exposed to hyperglycemic plasma

Fructosamine

TESTS FOR MONITORING GLYCEMIC CONTROL:

• Represents glycosylated proteins, especially albumin.

• Used to assess glycemic control over the past 2-3 weeks in cases when HbA1c is unreliable.

  • Half life of Alb = 17 days

• Has the advantage of using serum samples but is unreliable when serum albumin level is < 3 g/dL or if patient has hypoalbuminemia/hypoproteinemia.

• Reference values: 205-285 umol/L

Microalbuminuria

TESTS FOR MONITORING GLYCEMIC CONTROL:

• Early indicator of diabetic nephropathy

• Persistent albuminuria in two out of three urine collections 20-200 ug/min (AER), 30-300 mg/24 h, or an albumin-creatine ratio of 30-300 ug/mg (ACR) or 3.5-30 mg/mmol within a 3 to 6 month period

  • 30-300 mg/24h - Spx = Timed specimen

  • 3 - 6 month period - Spx random specimen

7mg/dl @ RT; 2 mg/dl/h (ref)

METHODS OF GLUCOSE MEASUREMENT:

• SPECIMEN CONSIDERATIONS

  • Use of NaF or SST to prevent glycolysis. Otherwise, glycolysis will take place at a rate of _______________________

    • For NaF use iodoacetate (if BUN or CREA; does not inhibit urease)

  • Effect of dextrose contamination ↑PG (500 mg/dl)

• Copper Reduction

• Ferric Reduction

• Condensation

What are example the Chemical Methods?

Copper Reduction

CHEMICAL METHODS:

• Benedicts Reaction

  • Common initial reaction of the _______

• Non - specific because glucose is not the only one that can catalyze the initial reaction

Folin Wu

UNDER COPPER REDUCTION:

• Cu + PMA → phosphomolybdenum

  • PMA = OH

  • Disadvantage: non specific

  • Increases due to other reducing agents

Nelson-Somogyi

UNDER COPPER REDUCTION:

• Cu + AMA → arsenomolybdenum

Neocuproine

UNDER COPPER REDUCTION:

• Cu + neocuproine → Cu − neocuproine

• is a simple complex formation between Cuprous ion and neocuproine

• this is in yellow orange color

blue

• Phosphomolybdenum and Arsenomolybdenum is _____ in color.

  • Intensity of color is monitored spectrophotometrically

  • Color is directly proportional to the level of Cuprous ions.

Ferric Reduction

CHEMICAL METHODS:

• _______ (yellow orange) is reduced to ferrocyanide (colorless)

• _________ is also called as Inverse colorimetry or Hagedorn Jensen method

  • Monitors the disappearance of color

Condensation

CHEMICAL METHODS:

• Dubowski Method - Most specific, popular, and best amongst all chemical methods

  • Not affected by oxidizing and reducing agents

• The intensity of the color is monitored spectrophotometrically.

  • Color is proportional to the level of glucose

Glucose oxidase

ENZYMATIC METHODS:

• Most popular and most commonly used enzymatic method

• Glucose is oxidized to gluconic acid and hydrogen peroxide (H2O2)

  • Catalyzed by the enzyme glucose oxidase

• Hydrogen peroxide is used as an oxidizing agent

Peroxidase-coupled/Trinder reaction

2 Detection Methods for Glucose Oxidase:

• subject to many interferences

• Colorimetric / Spectrophotometric

• More routinely used

• Serum glucose determination chromogen:

  • 4-aminophenozone oxidized to quinonimine (red purple)

  • Absorbance: 500nm

Polarographic

2 Detection Methods for Glucose Oxidase:

• measurement of the degree of O2 consumption using a pO2 (Clark) electrode (internal glucose)

• requires addition of molybdate and iodide or catalase and ethanol to prevent the re-formation of oxygen (source of error)

• Better because it is not affected by reducing and oxidizing agents

• Measures the amount of oxygen consumed in the reaction by detecting the amount of oxygen left

• Oxygen consumed is proportional to the amount of glucose in the sample

Hexokinase

ENZYMATIC METHODS:

• reference method for glucose; coupling reaction is highly specific

• effect of hemolyzed/icteric sample F↓ (source of error)

  • Hemoglobin interferes of glucose

• UV Method ; Involves UV measurement at 340nm

Glucose Dehydrogenase

ENZYMATIC METHODS:

• Highly specific for glucose, not subject to interference from substances normally found in serum and provides results in close agreement with hexokinase method.

• Not commonly used except in glucose POCT (glucometer)

Formula of Non-Colorimetric Method

This is the Formula of Non-Colorimetric or Colorimetric Method of Glucose Dehydrogenase?

• Measure using NADPH at A 340 nm

• Tetrazolium dye may be used to enable colorimetric spectrophotometric measurement

Colorimetric Method

This is the Formula of Non-Colorimetric or Colorimetric Method of Glucose Dehydrogenase?

• Formazan = BLUE

Galactosemia

INBORN ERRORS OF CARBOHYDRATE METABOLISM:

• due to a deficiency of one of three enzymes involved in galactose metabolism: galactose-1-phosphate uridyl transferase (GALT), galactokinase (GALK), or uridine diphosphate galactose-4-epimerase (GALE)

• affected children present with mental retardation, failure to thrive, and galactosuria

Hepatic glycogenoses

INBORN ERRORS OF CARBOHYDRATE METABOLISM:

UNDER Glycogen Storage Diseases/Glycogenoses:

• Usually manifest with hepatomegaly, hypoglycemia, and growth retardation

• von Gierke disease (Type 1a)

  • Most common hepatic glycogenosis

  • Deficiency of the enzyme glucose-6-phosphatase

  • Present with hypoglycemia, lactic acidosis, and hyperuricemia.

von Gierke disease

▪ Most common hepatic glycogenosis

▪ Deficiency of the enzyme glucose-6-phosphatase

▪ Present with hypoglycemia, lactic acidosis, and hyperuricemia.

Muscle glycogenosis

• Manifests with exercise intolerance, muscle cramps, fatigue, and weakness (Type V & VIII)

  • ↑ skeletal muscle enzymes: CK, AST LD, aldolase

1. Surface

2. Core

Components of Lipoproteins are:

Surface

These are under what component of lipoproteins?

• Apolipoproteins - protein moietics

• Phospholipids

• Non-esterified cholesterol

Phosphilipid (PL) and Non-esterified Cholesterol (NEC)

These Two Surface proteins are Amphipathic Lipids (w Polar/Non-Polar grps)

Core

These are under what component of lipoproteins?

• Triglycerides

• Cholesterol esters

• Free fatty acids

Triglycerides

Cholesterol esters

Free fatty acids

These Three Core proteins are Neutral Lipids

Lecithin cholesterol acyltransferase (LCAT)

• catalyzes the esterification of cholesterol

LDL Receptor (LDL-R)

• mediates the endocytosis of lipoproteins especially LDL

Lipoprotein lipase (LPL)

• catalyzes the hydrolysis of TG in lipoproteins releasing free fatty acids and glycerol to tissues

Exogenous pathway

This is the process of _____?

• Dietary Lipids → Intestine → Chylomicrons → needs LPL & CII → to hydrolyze to Chylomicrons Remnants → liver will use the chylomicrons remnants in the synthesis of the VLDL

  • to be continued

huge size

Note that chylomicrons are not taken up by the liver because of ______

Endogenous pathway

This is the process of _____?

• VLDL → needs LPL → hydrolyze into smaller IDL → needs LPL → to much smaller LDL

LDL

_____ is considered as a metabolite of VLDL as it comes with the metabolism of VLDL that can easily be taken up by the liver and the peripheral cells.

Atherogenic

• if the amount of cholesterol delivered to peripheral tissues is in excess.

De Novo Synthesis

Liver Synthesizes using ____________

Phospholipids

What is the major lipid component (excluding the protein) of the HDL?

IDL

MINOR AND ABNORMAL LIPOPROTEINS:

• lipolytic product of VLDL catabolism taken up by the liver or converted to LDL;

• density, electrophoretic mobility, protein and lipid contents are intermediate between those of VLDL and LDL

• It is minor because it is only intermediate in the metabolism of VLDL

β-VLDL

MINOR AND ABNORMAL LIPOPROTEINS:

• “floating β lipoprotein”

• richer in cholesterol than VLDL (VLDL-C/TG ratio>0.3); associated with Apo E2 isoform which has low affinity for the LDL receptor leading to dysbetalipoproteinemia

• Structure is similar to VLDL

• It has a much lower density than the typical VLDL

• The higher the lipid content, the lower the density, the more that the particle floats

Lp(a)

MINOR AND ABNORMAL LIPOPROTEINS:

• “sinking pre-β lipoprotein”

• Structure is similar to LDL

• Contains the prothrombotic Apo(a) which is homologous with plasminogen

• Associated with stroke, MI, CHD (increased protein content)

• inhibits fibrinolysis.

Plasmin

________ is an important fibrinolytic factor

LpX

• abnormal lipoprotein associated with obstructive biliary disease and LCAT Deficiency (catalyzes the esterification of cholesterol)

• Consists mostly of phospholipids and non-esterified cholesterol

Xanthomas

• cutaneous lesions due to accumulation of lipids in the eyelids (xanthelasma), Achilles and extensor tendons (tendinous xanthoma), extensor surfaces (eruptive xanthoma), and palm and wrist creases (palmar xanthoma)

↑ Chylo and/or VLDL

FREDRICKSON CLASSIFICATIONOF HYPERLIPOPROTEINEMIAS additional info:

• ↑TG = acute pancreatitis (xanthomas) = ↑risk pancreatitis

↑ LDL

FREDRICKSON CLASSIFICATIONOF HYPERLIPOPROTEINEMIAS additional info:

• ↑ Total Cholesterol (xanthelasmas) = ↑ risk Coronary heart disease

mutation or genetic mutation

Main cause of Hypolipoproteinemia is _____________

Abetalipoproteinemia

HYPOLIPOPROTEINEMIAS:

• AKA Bassen-Kornzweig Syndrome

• An autosomal recessive disorder involving mutations in the MTTP gene with absolute nonexistent levels of apoB48 and apoB100

  • Absence of Apo B-containing liproproteins (VLDL, LDL, CM)

  • Total Cholesterol = Very low

  • Triglyceride = Nearly undetectable

• Defect in APOB containing lipoprotein

Hypobetalipoproteinemia

HYPOLIPOPROTEINEMIAS:

• autosomal dominant disorder caused by nonsense or missense mutations in the apo B gene;

• low total cholesterol and triglyceride levels

• Decreased level of TC and TG

• Defect in APOB containing lipoprotein

Tangier disease

HYPOLIPOPROTEINEMIAS:

• Rare

• Autosomal recessive disorder characterized by low to undetectable HDL due to a mutation in the ABCA1 gene

• Defect in HDL

Hypoalphalipoproteinemia

HYPOLIPOPROTEINEMIAS:

• Defect in HDL

• Common autosomal dominant disorder characterized by HDL-C Levels → <30 mg/dL in men → <40 mg/dL in women

• High risk for CHD because of low HDL level

• HDL is inversely related to cardiac risk.

Abetalipoproteinemia & Hypobetalipoproteinemia

These Hypolipoproteinemias are Associated with Defects in Apo B

Tangier disease & Hypoalphalipoproteinemia

These Hypolipoproteinemias are Associated with Defects in HDL

Chemical Methods for Cholesterol

PLASMA LIPID ANALYSIS (ANALYTICAL METHOD)

• This formula is for?

• Saponification using alcoholic potassium hydroxide which catalyzes the hydrolysis of cholesterol or cholesteryl ester to separate or release free cholesterol from fatty acid

Saponification

What Step for Chemical Method?

Reagent:

• Alcoholic potassium hydroxide (KOH)

Purpose:

• Hydrolysis of cholesterol esters

Extraction

What Step for Chemical Method?

Reagent:

• Bloor’s reagent (Ethanol-ether)

Purpose:

• Removal of protein interference

Purification

What Step for Chemical Method?

Reagent:

• Digitonin

Purpose:

• Precipitation of free cholesterol

Colorimetry

What Step for Chemical Method?

Reagent:

• H2SO4, acetic anhydride or ferric ions

Purpose:

• Formation of colored compound

Liebermann-Burchardt

Chemical Methods for Cholesterol:

• Colorimetry

• Acetic anhydride is the reagent used

• Cholestadienly MSA is green in color