8. Carbohydrates 1

7/28/2019 8. Carbohydrates 1

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CARBOHYDRATES


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Contents

1. Introduction

2. Pathways of Glucose Metabolism

3. Regulation of Glucose Metabolism

4. Disease states in Glucose Metabolism

Hyperglycemia

Hypoglycemia

5. Diagnosis of patients with Glucose MetabolicAlterations


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Introduction

Primary energy source stored primarily as glycogen

Disease status involved hyperglycemia and hypoglycemia

Contain C, H, and O (Cx (H20)y with C=O andOH functional groups


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Introduction

Carbohydrate Models


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Introduction

Classification Definition

Monosaccharides

or simple sugars

Cannot be hydrolyzed to a simpler form

Contain 3, 4, 5, 6 carbon atoms

(triose, tetroses, pentoses and hexoses, etc.)

Examples include fructose, glucose, galactose


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Introduction


Disaccharides

Formed by interaction of two monosaccharides

Examples

Maltose = glucose + glucose

Lactose = glucose + galactoseSucrose = glucose + fructose


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Introduction


Polysaccharides Linkage of many monosaccharide units

Include starch, glycogen and glycogen

Starch

Cellulose

Glycogen


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Glucose Metabolism


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Glucose Metabolism


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Glucose Metabolism

1

GlycolysisMetabolism of glucose to lactate or pyruvate

for production of energy

GluconeogenesisFormation of glucose-6-phosphate from non

carbohydrate source

Glycogenolysis Breakdown of glycogen to glucose for use as

energy

Glycogenesis Conversion of glucose to glycogen for storage

Lipogenesis

Conversion of carbohydrates to fatty acidsLipolysis Decomposition of fat


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Glucose Metabolism

1

Glycolysis

(EMP Pathway)

Metabolism of glucose to lactate or

pyruvate for production of energy

GlucoseInsulinATP +lactate/pyruvate


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Glucose Metabolism

1

Gluconeogenesis

Formation of G-6-P from non

carbohydrate source

Fats (ketone bodies), Protein (urea nitrogen)


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Glucose Metabolism

1

Glycogenesis Conversion of glucose to glycogen

GlucoseInsulinGlycogen


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Glucose Metabolism

1

GlycogenolysisBreakdown of glycogen to G-6-P

GlycogenGlucagonGlucose


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Glucose Metabolism

1

Glycolysis

(EMP Pathway)

Metabolism of glucose to lactate or pyruvate

for production of energy

GlucoseInsulinATP + lactate/pyruvate

Gluconeogenesis

Formation of glucose-6-phosphate from non

carbohydrate source

Fats glucose + ketone bodies

Proteinglucose + urea nitrogen

Glycogenolysis

Breakdown of glycogen to glucose for use as

energy GlycogenGlucagonGlucose

Glycogenesis Conversion of glucose to glycogen for storage GlucoseInsulinGlycogen


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Glucose Metabolism

1

Lipogenesis Conversion of carbohydrates to fatty acids

Lipolysis Decomposition of fat


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Glucose Metabolism

1

Glycolysis GlucoseInsulinATP + lactate/pyruvateGluconeogenesis Fats (ketones), Protein (urea nitrogen)

Glycogenolysis GlycogenGlucagonGlucoseGlycogenesis GlucoseInsulinGlycogenLipogenesis Conversion of carbohydrates to FA

Lipolysis Decomposition of fat


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CONTENTS

1. Introduction




Hyperglycemia

Hypoglycemia



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Regulation of Glucose Metabolism

Glucagon (hyperglycemic agent)

1. Primary hormone responsible increasing blood glucose

2. Synthesized by the cells of the islets of Langerhan (pancreas)

3. glycogenolysis and gluconeogenesis.


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Epinephrine

1. Produced by the adrenal medulla, blood glucose

2. Released during times of physical and emotional stress

3. Inhibits insulin secretion, glycogenolysis and lipolysis
http://upload.wikimedia.org/wikipedia/commons/c/c6/Illu_endocrine_system.jpg


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Cortisol (Glucocorticoids)

1. Produced by the adrenal cortex, plasma glucose

2. intestinal entry of glucose into the cell, gluconeogenesis,

glycogenolysis and lipolysis


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Glucose Metabolism

Growth hormone

1. Produced by the anterior pituitary gland; plasma glucose

2. glucose entry to cells, glycolysis


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Glucose Metabolism

Thyroxine

1. Produced by the thyroid gland; plasma glucose

2. glycogenolysis, gluconeogenesis and glucose intestinal

absorption


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Glucose Metabolism

Somastostatin

1. Produced by the Delta cells of the islet of Langerhans in the

pancreas and hypothalamus

2. plasma glucose by inhibition of insulin, glucagon, GH, etc.


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1. Insulin

2. Glucagon

3. Epinephrine

4. Cortisol

5. Growth hormone6. Thyroxine

7. Somatostatin


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CONTENTS

1. Introduction




i. Hyperglycemia

ii. Hypoglycemia



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Hyperglycemia

Increase in plasma glucose

Insulin is secreted in the cells of pancreatic islets

Increase in Plasma Glucose


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Hyperglycemia

Diabetes Mellitus

Metabolic disease characterized by hyperglycemia resulting

from defects in insulin secretion, insulin action or bothDiabetes Mellitus

1. Type 1 (IDDM)

2. Type 2 (NIDDM)

3. Other

4. Gestational


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Hyperglycemia

Diabetes Mellitus

ClassificationPathogenesis

1. Type 1 (IDDM) -Cell destruction

Absolute insulin deficiency

Autoantibodies


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Hyperglycemia

Diabetes Mellitus

ClassificationEpidemiology and Pathophysiology

1. Type 1 (IDDM) 5-10% of all cases of diabetes

Occurs in childhood and adolescence

Absence of Insulin with excess in glucagon


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Hyperglycemia

Diabetes Mellitus

ClassificationCharacteristics

1. Type 1 (IDDM) Abrupt onset

Insulin dependence, ketosis tendency

Sign and Symptoms

Polydipsia

Polyphagia

Polyuria


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Hyperglycemia

Diabetes Mellitus


from defects in insulin secretion, insulin action or bothDiabetes Mellitus

Classification

1. Type 1 (IDDM)

2. Type 2 (NIDDM)

3. Other

4. Gestational


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Hyperglycemia

Diabetes Mellitus

ClassificationEpidemiology

2. Type 2 (NIDDM) 90% of all cases of diabetes

Adult onset


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Hyperglycemia

Diabetes Mellitus

ClassificationPathogenesis and Pathophysiology

2. Type 2 (NIDDM) Insulin resistance w/ secretory defect

Relative insulin deficiency with age, obesity and lack of exercise

Insulin is present (hyperinsulinemia)

Glucagon secretion is attenuated


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Hyperglycemia

Diabetes Mellitus

ClassificationCharacteristics

2. Type 2 (NIDDM) Non Insulin dependent

Ketosis tendency is seldom Greater tendency to develop

hyperosmolar states

Polydipsia, Polyphagia, Polyuria


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Hyperglycemia

Diabetes Mellitus


from defects in insulin secretion, insulin action or bothClassification

1. Type 1 (IDDM)

2. Type 2 (NIDDM)

3. Other

4. Gestational


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Diabetes Mellitus


3. Others Associated with secondary conditions

Hyperglycemia

Diabetes Mellitus


3. Others Associated with secondary conditions

4. Gestational Glucose intolerance during pregnancyDue to metabolic and hormonal changes


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Hyperglycemia

Diabetes Mellitus


from defects in insulin secretion, insulin action or bothClassification1. Type 1 (IDDM)

2. Type 2 (NIDDM)

3. Other

4. Gestational


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Diagnostic Criteria for Diabetes Mellitus

Hyperglycemia

Categories of Fasting Plasma Glucose (FPG)


1. Random plasma glucose 200mg/dL, + symptoms of diabetes



2. Fasting plasma glucose 126 mg/dL




3. 2-h plasma glucose 200 mg/dL during an OGTT


Provisional diabetes diagnosis FPG 126 mg/dL



Impaired fasting glucose FBG 100-125 mg/dL



Impaired fasting glucose FBG 100-125 mg/dL

Normal fasting glucose FBG


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Hyperglycemia




3. 2-h plasma glucose 200 mg/dL during an OGTT

Categories of Oral Glucose Tolerance

Provisional diabetes diagnosis 2-h PG 200 mg/dL

Impaired Glucose Tolerance 2-h PG 140-199 mg/dL

Normal Glucose Tolerance 2-h PG


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Hypoglycemia

Causes of Hypoglycemia

b. Patients Appears ill

a. Patients Appears Healthya. Patients Appears Healthy

No coexistingdisease

Insulinoma, Islet hyperplasia

Factitial hypoglycemia (insulin/sulfonylurea)

Severe exercise, Ketotic hypoglycemia

a. Patients Appears Healthy

No coexistingdisease

Insulinoma, Islet hyperplasia

Factitial hypoglycemia (insulin/sulfonylurea)

Severe exercise, Ketotic hypoglycemia

Compensated

coexistentDrugs/disease

b. Patients Appears ill

Drugs, Predisposing illness, Hospitalized patient


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Genetic disorders

Genetic Defects in Carbohydrate MetabolismGenetic Defects in Carbohydrate Metabolism

Von Gierke Disease

(glucose-6-phosphatase

deficiency type 1)

Glycogen build up in the liver

due to inhibition of hepatic

glycogenolysis

Genetic Defects in Carbohydrate Metabolism (Glycogen

Storage diseases )

1. Von Gierke Disease(glucose-6-phosphatase

deficiency type 1)

Glycogen build up in the liver and

kidney due to inhibition ofhepato-renal glycogenolysis

Glycogen storage or glycogen

deposition in the tissue

Lack of glycogenolysis under the

stimulus of glucagon or

epinephrine.

Ketosis and hyperlipemia are

also present.

Glucose 1-phosphate and


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Genetic disorders


Von Gierke Disease


deficiency type 1)



glycogenolysis

Genetic Defects in Carbohydrate Metabolism

2. Pomps disease

(alpha 1,4 D-glucosidase

deficiency )

Glycogen storage in the muscle.

1,4 glucosidase acts on the 1.4

linkagesMaltose in the liver is not

hydrolyzed in this defect.

Transglycosidation reaction is

possible

1.4 glycosidase can releaseglucose from maltose and other

sources.


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Genetic disorders


Von Gierke Disease


deficiency type 1)



glycogenolysis


3.Mc Ardle Syndrome

(Phosphorylasedeficiency )

Glycogen storage in the muscle.

phosphorylase deficiency in the

skeletal muscle.

Hepatic phosphorylase activity

is normal due to increase in blood

glucose after administration of

glucagon and epinephrine.

Patient has normal strengthbefore exercise, after exercise, he

develops cramps.


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Genetic disorders


Von Gierke Disease


deficiency type 1)



glycogenolysis


4. Amylopectinosis(Deficiency of the branching

enzyme)

Abnormal Glycogen storage in

the liver with long inner and outer

branching

Abnormal glycogen is also

stored in the spleen and lymph

glands

Precipitation of abnormal

glycogen in the liver.


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Genetic disorders


Von Gierke Disease


deficiency type 1)



glycogenolysis


5. Limit Dextrinosis

(Deficiency of the branching

enzyme, amylo-6-glucosidase)

Glycogen abnormal storage in

the liver, heart, and muscle with an

excess of short outer branches

Precipitation of abnormal

glycogen in the liver.


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Genetic disorders


Von Gierke Disease


deficiency type 1)



glycogenolysis


Galactosemia

(galactose-1-phosphate uridyl

transferase dificiency)

Accumulationof Galactose 1-

phosphate in the red cells due todeficiency of galactose 1-

phosphate uridyl transferase

leading to depletion of ATP.

Gal -1 phosphate and udp

glucose -------/ UDP-Galactose and

glucose 1-phosphate

It is manifested as the patient

grows older ( Increasing tolerance

to galactose


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Genetic disorders


Von Gierke Disease


deficiency type 1)



glycogenolysis


Druginduced Hemoytic

Anemia

(glucose 6-phosphate

deficiency)

Deficiency of glucose 6-

phosphate in the red cell Glucose 6phosphate is used to

main the normal red cell

membrane stability)

in the red cell, oxidative

metabolism of glucose is via

hexose monophosphate pathway.


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Genetic disorders


Tay Sachs

(Missing hexosaminidase)

Faulty ganglioside metabolism

Pentosuria(NAD-linked L-xylitol

Dehydrogenase deficiency)

L-xylose and Arabinose are

excrtred Enzyme in monophosphate shunt


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Diagnosis of Glucose Metabolic Alterations

Methods:

1. Fasting Blood Glucose

2. POC

3. 2-Hr Post Prandial Sugar

4. OGTT

5. HbA1C


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Non Enzymatic Methods of Glucose Measurement

1. Nelson Somogyi

2. Hagedorn Jensen

3. Ortho-toluidine (Dubowski)

Enzymatic Methods of Glucose Measurement

1. Glucose oxidase (Saifer Gernstenfield)

2. Hexokinase (Reference method)

3. Clinitest


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1. Nelson Somogyi

Copper reduction method (uses BaSO4 to remove saccharoids)

Glucose + arsenomolybdic acidarsenomolybdenum blue


1. Nelson Somogyi


Glucose + arsenomolybdic acid arsenomolybdenum blue

2. Hagedorn Jensen

Ferric reduction method (inverse colorimetry)

Glucose + Ferricyanide (yellow) Ferrocyanide (colorless)

Non Enzymatic Methods of Glucose MeasurementNon Enzymatic Methods of Glucose Measurement

1. Nelson Somogyi


Glucose + arsenomolybdic acid arsenomolybdenum blue

2. Hagedorn Jensen

Ferric reduction method (inverse colorimetry)

Glucose + Ferricyanide (yellow) Ferrocyanide (colorless)3. Ortho-toluidine (Dubowski)

Condensation of carbohydrates with aromatic amines producing

Schiff bases (green)


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1. Nelson Somogyi

2. Hagedorn Jensen





3. Clinitest


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-D-glucose + O2 +H2Oglucose oxidasegluconic acid + H2O2

H2O2 + reduce chromogenperoxidaseoxidized chromogen + H2O




H2O2 + reduce chromogenperoxidaseoxidized chromogen + H2Oa. Couple reaction is known as Trinders reaction

False Low results due to uric acid, bilirubin and ascorbic acid




H2O2 + reduce chromogenperoxidaseoxidized chromogen + H2Oa. Couple reaction is known as Trinders reaction

False Low results due to uric acid, bilirubin and ascorbic acid

b. O2 Consumption electrode (polarographic glucose analyzers)

measure oxygen depletion


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2. Hexokinase (reference method)

Glucose + ATPhexokinaseglucose 6-PO4 + ADP

Glucose 6-PO4 + NADP+G-6-PDNADPH + H+ + 6-phosphogluconate




Glucose 6-PO4 + NADP+G-6-PDNADPH + H+ + 6-phosphogluconatea. in absorbance is measured at 340 nm

b.False low results due to gross hemolysis and bilirubin


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f l b l l


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1. Nelson Somogyi

2. Hagedorn Jensen





3. Clinitest

f l b l l


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Methods:


2. POC

3. 2-Hr Post Prandial Sugar

4. OGTT

5. HbA1C

i i f l b li l i


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Self-Monitoring of Blood Glucose

1. Type 1 diabetes 3 to 4 times/day


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Di i f Gl M b li Al i


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2-Hour Postprandial Tests

A solution (75g of glucose) is

administered and a specimen is

drawn 2 hrs. later

Oral Glucose Tolerance Test

FBS is taken. Glucose load is

administered. Blood glucose is

determined in 30 min, 1st

, 2nd

and 3rd hrs.

Di i f Gl M b li Al i


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Methods:


2. POC

3. 2-Hr Post Prandial Sugar4. OGTT

5. HbA1C

Di i f Gl M t b li Alt ti


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HbA1C Measurement


HbA1C Measurement

Index for long term plasma glucose control (2-3 month period)

HbA1C Measurement


Based on charged differences between HbA1C and Non-HbA1C

HbA1C Measurement


Based on charged differences between HbA1C and Non-HbA1C

Specimen requirement is EDTA WB sample. N.V 4.5 to 8.0%



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A. Structural differences

1. Immunoassays

2. Affinity Chromatography


B. Charge differences

1. Cation-exchange Chromatography

2. Electrophoresis3. Isoelectric focusing

4. HPLC

Methods of HbA1C Measurement based on:



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Methods:


2. POC


5. HbA1C

CONTENTS


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CONTENTS

1. Introduction



4. Disease states in Glucose Metabolismi. Hyperglycemia

ii. Hypoglycemia



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Ketone


Ketone

Produced by the liver through

metabolism of stored lipids

Ketone



3 ketone bodies

Acetone (2%)

Acetoacetic acid(20%)

3--hydroxybutyric acid (78%)

Ketone



3 ketone bodies

Acetone (2%)

Acetoacetic acid(20%)

3--hydroxybutyric acid (78%)

Ketonemia

accumulation of ketones in blood

Ketonuria

accumulation of ketones in urine



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Mtds. of Ketone Measurement



1. Gerhardts Test

Acetoacetic acid + Ferric chloride

Red color


1. Gerhardts Test


Red color2. Nitroprusside

Acetoacetic acid + nitroprusside

alkaline pHPurple color


1. Gerhardts Test


Red color2. Nitroprusside

Acetoacetic acid + nitroprusside

alkaline pHPurple color3. Enzymatic

NADH + H+ + acetoacetic acid

-HBDNAD + -hydroxybutyric acid



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Methods:


2. POC


5. HbA1C

6. Ketone7. Microalbuminuria



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Microalbuminuria

Early stage diabetic renal nephropathy

Persistent albuminuria (30-299 mg/24h or alb./crea. 30-300 g/mg




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Methods:


2. POC


5. HbA1C

6. Ketone7. Microalbuminuria

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8. Carbohydrates 1