HOMOCYSTEINE: BIOSYNTHESIS AND HEALTH IMPLICATIONS

HOMOCYSTEINE: BIOSYNTHESIS AND HEALTH IMPLICATIONS

Contents

Preface

References

Chapter I Enzyme Misfolding As a Common Pathogenic Mechanism in Cystathionine Beta-Synthase (CBS)-Deficient Homocystinuria: Rescue of CBS Mutants with Chemical Chaperones

Abstract

Abbreviations

Introduction

Material and Methods

Chemicals

Mutant CBS Construct Preparation

Preparation of 6xHis-Tagged CBS Constructs

Preparation of Crude Extracts

Mutant CBS Protein Expression and Purification

Protein Gel Electrophoresis and Western Blot

CBS Activity Assay

Spectroscopic Characterization

Thermostability Determinations

Results

Screening of Chemical Chaperones in E. Coli Yields Optimal Conditions for Mutant CBS Expression

The R266K CBS Is Active When Expressed with a Short Affinity (6xHis) Tag Instead of Bulky GST Partner

Purified CBS Mutants Retain an Active Conformation

Purified Mutant CBS Enzymes Are Fully Saturated with Heme

Purified CBS Mutants Are at Least As Active As WT

Thermal Pre-Treatment or AdoMet Addition Results in CBS Activation

CBS Mutants, Except R266K, Are at Least as Thermostable as WT

Chemical Chaperones May Act Indirectly via Activation of Molecular Chaperones

Conclusion

Acknowledgment

References

Chapter II Therapeutic Strategies in Murine Models of Hyperhomocysteinemia

Abstract

Introduction

Polyphenols, a New Direction in the Prevention of Cardiovascular Disease

Classification and Sources of Polyphenols

(a) Phenolic Acids

(b) Lignans

(c) Stilbenoids

(d) Flavonoids

(e) Flavonols

(f) Flavones

(g) Flavanones

(h) Isoflavones

(h) Flavanols

(i) Anthocyanidins

Polyphenols and Hyperhomocysteinemia

(a) What Dose?

(b) Effect on Hepatic Fibrosis

(c) Effect on Hepatic Oxidative Stress

(d) Effect on Hepatic Xenobiotic Metabolizing Enzymes

(e) Effect on Endothelial Function

DYRK1A, a Novel Regulator of the Methionine-Homocysteine Cycle

DYRK1A, a Serine/Threonine Kinase

DYRK1A and Homocysteinemia in Murine Models of Down Syndrome

Therapeutic Targeting of DYRK1A to Normalize Hyperhomocysteinemia

Conclusion

References

Chapter III Homocysteine and Neurodegeneration: Current Concepts and Potential for Intervention

Abstract

Introduction

Homocysteine and Neuronal Degeneration

Homocysteine and Neuronal Function

Discussion

Conclusion

References

Chapter IV Homocysteine and Apoptotic Factors in Epileptic Patients Treated with Anti-Epileptic Drugs

Abstract

Introduction

Apoptosis in the Cell

The Extrinsic Apoptotic Pathway

The Intrinsic Apoptotic Pathway

Other Apoptotic Pathways

The Role of p53 Protein in Apoptosis

The Role of the Bcl-2 Protein Family in Apoptosis

The Role of Caspases in Apoptosis

Apoptosis and Antiepileptic Drugs

Older Generation AEDs and Apoptosis

Valproic Acid

Carbamazepine

Phenytoin

Phenobarbital

Newer Generation Antiepileptic Drugs

and Apoptosis

Levetiracetam

Oxcarbazepine

Lamotrigine

Topiramate

Gabapentin

Pregabalin

Vigabatrine

Zonisamide

Homocysteine and Apoptosis

Methods

Homocysteine Levels and Antiepileptic Drugs in Epileptic Patients

Patients

Analysis of Plasma Hcy Concentration

Determination of Hcy Concentration

Results

Apoptotic Proteins, Apoptotic Cells and Antiepileptic Drugs in Epileptic Patients

Patients

Isolation of Apoptotic Proteins

Western Blot Analysis

Analysis of Apoptotic Cells

Flow Cytometry Analysis

Results

Homocysteine, Apoptotic Proteins, Apoptotic Cells and AEDs in Epileptic Patients

Patients

Analysis of Hcy, Apoptotic Proteins and Apoptotic Cells

Results

Conclusion

References

Chapter V Homocysteine and Uremia

Abstract

Abbreviation List

Introduction

Hyperhomocysteinemia in Uremic Patients

Biochemical Basis

Determinants of Plasma tHcy Levels

Homocysteine Metabolism

1. Pathway for Homocysteine Synthesis

1.1. Transmethylation Pathway

2. Pathways for Homocysteine Degradation

2.1. Trans-Sulfuration Pathway

2.2. Remethylation Pathways

Genetic Factors

Acquired Factors

Chronic Kidney Disease

Pathophysiology of Endothelial Damage Induced by Hyperhomocysteinemia

Asymmetric Dimethylarginine (ADMA) and Homocysteine

Hyperhomocysteinemia: Therapeutic Strategies

1. Folic Acid and B Vitamins

2. N-acetylcysteine

3. Hemodiafiltration

Erythrocyte Glutathione Transferase Activity and Homocysteine

References

Chapter VI Homocysteine: An Innovative Risk Factor for Anemia, Bone Disease, and Vascular Disease in Chronic Renal Failure Patients

Abstract

Introduction

Homocysteine and Vascular Disease

Homocysteine and Bone Disease

Homocysteine and Anemia

Methods

Results

Discussion

Conclusion

References

Chapter VII Plasma Homocysteine and Thiol Redox States in HIV+Patients

Abstract

Introduction

Cellular Redox Level, Oxidative Stress, and Redox Thiol Homeostasis

Oxidative Stress in HIV Infection

Low ThiolAntioxidant Capacity in HIV+ Patients

Enhancing Antioxidant Defenses in HIV+ Patients

1. Highly active anti-retroviral therapy (HAART)

2. Glutathione (GSH)

3. N-acetyl cysteine (NAC)

The Pivotal Role of Hcy in HIV-Induced Redox Status

Objectives

Methods

Results and Discussion

Conclusion

Acknowledgment

References

Chapter VIII Hyperhomocysteinemia and Association of Eye Disease

Abstract

Introduction

Age-related Macular Degeneration

Central Retinal Vein Occlusion

Age-related Cataracts

Glaucoma

The Pseudoexfoliation Syndrome

Behçet’s Disease

Conclusion

References

Chapter IX Homocysteine Concentrations in Obese Patients After Biliopancreatic Bypass Surgery

Abstract

Introduction

Material and Methods

Results

Discussion and Conclusion

References

Chapter X Celiac Disease, Hyperhomocysteinemia and Atherothrombosis: Relationship and Implications

Abstract

Introduction

Diagnosis of Celiac Disease

Mechanisms of Atherogenesis and Vasculopathy

The Homocysteine Pathway

The Role of Homocysteine in Celiac Disease

and Atherosclerosis

Thrombophilia and Vasculopathy in Celiac Disease

Implications for Management

Conclusion

References

Chapter XI Homocysteine Metabolism, Cardiovascular Disease and Psoriasis

Abstract

Introduction

Psoriasis and Cardiovascular Disease

Psoriasis and Hyperhomocysteinemia

Hyperhomocysteinemia and Atherosclerosis

Clinical Management of Psoriasis

Conclusion

References

Index