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Current Molecular Medicine
ISSN: 1566-5240

Current Molecular Medicine
Volume 6, Number 5, August 2006
Contents
Special Issue on Atherosclerosis
Executive Editors: Pedro R. Moreno, Javier
Sanz and Valentin Fuster

Editorial Pp. 437-438
I. Basic and Experimental
Cell Biology and Lipoproteins in Atherosclerosis Pp.
439-456
L. Badimon, J. Martínez-González, V. LLorente-Cortés,
C. Rodríguez and T. Padró
[Abstract]
Neovascularization in Human Atherosclerosis Pp.
457-477
P.R. Moreno, K.R. Purushothaman, E. Zias, J. Sanz and
V. Fuster
[Abstract]
Intraplaque Hemorrhage Pp. 479-488
A.P. Levy and P.R. Moreno
[Abstract]
Links Between Inflammation and Thrombogenicity
in Atherosclerosis Pp. 489-498
J.F. Viles-Gonzalez, V. Fuster and J.J. Badimon
[Abstract]
Metabolic Syndrome and Diabetic Atherothrombosis:
Implications in Vascular Complications Pp. 501-514
P. Meerarani, J.J. Badimon, E. Zias, V. Fuster and P.R.
Moreno
[Abstract]
Molecular Determinants of Vascular Calcification:
A Bench to Bedside View Pp. 515-524
S. Dellegrottaglie, J. Sanz and S. Rajagopalan
[Abstract]
II. Clinical Imaging and Biomarkers of Atherosclerosis
Calcium Scoring and Contrast-Enhanced CT Angiography
Pp. 525-539
J. Sanz, S. Dellegrottaglie, V. Fuster and S. Rajagopalan
[Abstract]
Plaque Imaging and Characterization Using Magnetic
Resonance Imaging: Towards Molecular Assessment Pp.
541-548
M. Sirol, V. Fuster and Z.A. Fayad
[Abstract]
Atherosclerosis Neovascularization and Imaging
Pp. 549-556
K.R. Purushothaman, J. Sanz, E. Zias, V. Fuster and P.R.
Moreno
[Abstract]
Cardiac Biomarkers for the Prediction and Diagnosis
of Atherosclerotic Disease and its Complications
Pp. 557-569
M.D. Weinberg, W.C. Hooper and G. Dangas
[Abstract]
III. Evolving Therapies for Native and Peri-Interventional
Coronary Artery Disease
The Role of High-Density Lipoprotein Cholesterol in
the Prevention and Possible Treatment of Cardiovascular Diseases
Pp. 571-587
B.G. Choi, G. Vilahur, D. Yadegar, J.F. Viles-Gonzalez and
J.J. Badimon
[Abstract]
Statin Therapy for Native and Peri-Interventional
Coronary Heart Disease Pp. 589-602
D.A. Smith and I. Galin
[Abstract]
Antithrombotic Therapy Pp. 603-619
W.L. Duvall
[Abstract]
Abstracts
[Back to top]
Editorial
Atherothrombosis continues to be the most important
cause of death and disability in western countries, and for
2020 will also be the main cause in developing countries.
Recent paramount research performed within the last few years
highlight the importance of new pathophysiological, clinical,
and therapeutic approaches to atherothrombosis, creating new
pathways for diagnosis, treatment and prevention. This supplement
organized in three sections is devoted to novel concepts covering
the disease, from early atherogenesis to plaque rupture and
thrombosis.
The first section entitled “Basic and Experimental”
is composed by six articles addressing the latest understanding
of the cellular and molecular mechanisms of the disease. In
the first review, entitled “Cell biology and lipoproteins
in atherosclerosis”, Dr. Badimon et al., review
the complex interaction among inflammatory cells, vascular
elements, and lipoproteins leading to early atherogenesis.
Specific attention is paid to the role of the endothelial
cell as the central player for cell adhesion, subendothelial
retention and modification of LDL, intracellular lipid accumulation,
and extracellular matrix formation in the vascular wall. In
the second review entitled “Neovascularization in human
atherosclerosis”, Dr. Moreno et al., review
the role of vasa vasorum in health and disease, covering the
cellular and molecular aspects of atherothrombosis neovascularization.
The role of neovessels from early atherogenesis to plaque
rupture and thrombosis is covered. Furthermore, the role of
neovessels in restenosis and plaque regression is also addressed,
providing the reader extensive knowledge in this evolving
and promising field. In the third article entitled “Intraplaque
Hemorrhage” Dr. Levy et al., review the pathophysiological
consequences of red blood cell extravasation within atherosclerotic
lesions, focusing on the potent oxidative and pro-inflammatory
effects of Hemoglobin, leading to macrophage activation and
plaque destabilization. The main defense mechanism against
hemoglobin, the protein Haptoglobin is also reviewed, with
special attention to the diabetic population. In the fourth
article entitled “Link between inflammation and thrombogenicity
in atherosclerosis” Dr. Viles et al., review
the concept of vulnerable plaque, vulnerable blood, and vulnerable
patient. Of note, the role of tissue factor, platelets, apoptosis,
and other pro-thrombotic mediators is elegantly addressed,
summarizing the interactions between inflammation and coagulation
within the setting of atherothrombotic disease. In the fourth
article of this section entitled “Metabolic syndrome,
diabetes, and peroxisomal proliferator activated receptors”
Dr. Meerarani., et al review the complex interaction
between insulin resistance, endothelial dysfunction, and pro-inflammatory
gene regulation leading to an increased atherothrombotic state.
The pivotal role of HDL and the emerging role of peroxisomal
proliferator activator receptors in disease stabilization
are also addressed, providing the reader with a comprehensive
approach to atherothrombosis in patients with metabolic syndrome.
Finally, in the last article of this section entitled “Molecular
determinants of vascular calcification: a bench to bedside
review” Dr. Dellegrottaglie et al., review
the mechanisms triggering osteogenesis of the vessel wall
associated with the loss of inhibitory factors responsible
for enhanced bone turnover. Of note, the interactions between
the receptor activator nuclear factor kB, the multiple pro-inflammatory
cytokines and the non-collagenous proteins including osteopontin
and osteoprotegrin, are reviewed.
The second section entitled “Clinical imaging and biomarkers
of atherosclerosis” is composed by four articles addressing
the state-of-the-art imaging approach for non-invasive diagnosis
and risk-stratification of patients with increased likelihood
of developing the disease. In the first article entitled “Calcium
scoring and contrast-enhanced CT angiography” Dr. Sanz
et al., review the clinical application of detecting
coronary calcium, and the recent advances in non-invasive,
CT coronary angiography. In the second article entitled “Plaque
imaging and characterization using magnetic resonance imaging:
toward molecular assessment” Sirol et al.,
review the use of high-resolution magnetic resonance for plaque
detection and characterization and the potentials of “molecular
Imaging”. A variety of molecules present in atherosclerotic
plaques serving as targets for specific contrast agents allow
for the identification of high-risk atherosclerotic lesions.
In the third article entitled “atherosclerosis neovascularization
and imaging” Dr. Purushothaman et al., specifically
review the role of multiple techniques to visualize neovessels
in the vessel wall, with special emphasis in molecular imaging.
Finally, in the fourth article entitled “Cardiac biomarkers
for the prediction and diagnosis of atherosclerotic disease
and its complications” Dr. Weinberg et al.,
review the current status of multiple inflammatory and pro-thrombotic
biomarkers to evaluate patients with increased risk of coronary
and systemic atherothrombosis. Of note, the impact of sex,
age, ethnicity, and co-morbid conditions is addressed, providing
the clinician with a through approach to the field of biomarkers
and atherothrombosis.
The third and last section entitled “Evolving therapies
for native and peri-interventional coronary artery disease”
is composed by three excellent review articles aimed to physicians
and scientists involved in patient care. In the first article
entitled “The role of high-density lipoprotein cholesterol
in the prevention and possible treatment of cardiovascular
diseases” Dr. Choi et al., review the atheroprotective
role of HDL, highlighting the anti-oxidant, anti-inflammatory,
and anti-thrombotic effects. In addition, the clinical evidence
associated with HDL levels is also reviewed, with emphasis
on the novel pathways to increase HDL in clinical practice.
In the second article entitled “Statin therapy”
Dr Smith et al., review the impressive clinical benefit
of statins in primary and secondary prevention of atherothrombotic
events. The multiple lipid and non-lipid related beneficial
effects including endothelial-dependent vasodilatation, decreased
inflammation, and overall reduction in atherosclerosis is
reviewed. Finally, in the last article of this review entitled
“Anti-thrombotic therapy” Dr. Duvall reviews the
cornerstone therapy for atherothrombosis using an evidence-based
approach for each individual group of medications. In the
anti-platelet group, the evidence supporting the use of Aspirin,
Thienopyridines, and Glycoprotein IIb/IIIa receptor inhibitors
is reviewed. In the anti-thrombotic group, unfractionated
and fractionated heparin, and direct thrombin inhibitors are
reviewed. Finally, the evidence associated with the use of
fibrinolytics in acute myocardial infarction provides to the
clinician a comprehensive approach to treat patients with
atherothrombotic disease.
Overall, this supplement is devoted to the novel concepts
that are creating new pathways in the diagnosis, treatment,
and prevention of atherothrombotic disease.
Pedro R. Moreno
The Cardiovascular Institute
Mount Sinai School of Medicine
Box 1030, New York
NY 10029, USA
E-mail: pedro.moreno@msnyuhealth.org
Javier Sanz
The Cardiovascular Institute
Mount Sinai School of Medicine
Box 1030, New York
NY 10029, USA
E-mail: Javier.Sanz@mssm.edu
Valentin Fuster
The Cardiovascular Institute
Mount Sinai School of Medicine
Box 1030, New York
NY 10029, USA
E-mail: Valentin.Fuster@msnyuhealth.org
[Back to top]
Cell Biology and Lipoproteins in Atherosclerosis
L. Badimon, J. Martínez-González, V. LLorente-Cortés,
C. Rodríguez and T. Padró
Atherosclerosis is an inflammatory process, triggered
by the presence of lipids in the vascular wall, and encompasses
a complex interaction among inflammatory cells, vascular elements,
and lipoproteins through expression of several adhesion molecules
and cytokines. Subendothelial retention of lipoproteins is
the key initiating event in atherosclerosis, provoking a cascade
of events to pathogenic response. High levels of plasma lipids,
particularly low-density (LDL) and very-low-density lipoproteins
(VLDL) are among the pathophysiologic stimuli that induce
endothelial dysfunction. Endothelial cells regulate coagulation,
thrombosis and the fibrinolytic system; the endothelium modulates
the activity of smooth muscle cells (vascular tone/proliferation)
and controls the traffic of macromolecules and inflammatory
cells to the vessel wall. Furthermore, LDLs have been implicated
in the induction of changes in permeability, cell adhesion
and secretion of vasoactive molecules (nitric oxide [NO]),
while VLDLs seem to modulate the fibrinolytic system [tissue
plasminogen activator (TPA) and plasminogen activator inhibitor-1
(PAI-1)]. In this review, we will focus on the pathophysiologic
functions of lipoproteins in the vascular wall.
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Neovascularization in Human Atherosclerosis
P.R. Moreno, K.R. Purushothaman, E. Zias, J. Sanz and
V. Fuster
In the absence of disease, microvessels provide vessel
wall nutrients to the tunica media, while the intima is fed
by oxygen diffusion from the lumen. As disease evolves and
the tunica intima thickens, oxygen diffusion is impaired,
and microvessels become the major source for nutrients to
the vessel wall. Microvessels serve as a port of entry for
inflammatory cells, from the systemic circulation to the nascent
atherosclerotic lesion. As disease progress, microvessels
also play a role in intraplaque hemorrhage, lipid core expansion,
and plaque rupture. In addition, microvessels are also involved
in stent restenosis, and plaque regression. Therefore, microvessels
are a pivotal component of atherosclerosis, and proper patient
risk-stratification in the near future may include the detection
of increased neovascularization in atherosclerotic lesions.
This review divided in two parts summarizes the current understanding
of atherosclerosis neovascularization, starting with the normal
anatomy and physiology and progressing to more advanced stages
of the disease. We will review the structure and function
of vasa vasorum in health and disease, the mechanisms responsible
for the angiogenic process, the role of the immune system,
including inflammation and Toll-like receptors, and the pathology
of microvessels in early atherosclerotic plaques. Furthermore,
the review addresses the advanced stages of atherosclerosis,
summarizing the progressive role for microvessels during disease
progression, red blood cell extravasation, lipid core expansion,
plaque rupture, healing, repair, restenosis, and disease regression,
offering the clinician a state-of-the-art, “bench to
bedside” approach to neovascularization in human atherosclerosis.
[Back to top]
Intraplaque Hemorrhage
A.P. Levy and P.R. Moreno
Intraplaque hemorrhage is a common feature of atherosclerotic
plaques and is considered one of the identifying features
of complex lesions preceding acute ischemic events. The cause
of intraplaque hemorrhage is most often secondary to rupture
of neovessels, which have invaded the plaque. However, inflammation
and metabolic factors such as diabetes may also precipitate
hemorrhage from mature microvessels by damaging the endothelium.
The mechanism by which hemorrhage destabilizes the plaque
is in large part secondary to the action of hemoglobin released
from red blood cells at the site of the hemorrhage. Hemoglobin
is a potent pro-inflammatory agent by virtue of its ability
to promote formation of ROS. The major defense mechanism against
the toxic effects of extracorpuscular hemoglobin is the protein
haptoglobin, which tightly binds to hemoglobin and prevents
it from catalyzing oxidative reactions. There exists a common
allelic polymorphism in the haptoglobin gene, which has recently
been strongly associated with the risk of cardiovascular disease
in multiple independent cohorts. The protein products of the
two different haptoglobin alleles differ in their ability
to serve as an antioxidant against hemoglobin and also to
activate the CD163 receptor. This review presents a unifying
hypothesis whereby the haptoglobin genotype is proposed to
modulate the response to intraplaque hemorrhage and thereby
play a fundamental role in determining the morphological and
metabolic features of complex plaques preceding acute ischemic
events.
[Back to top]
Links Between Inflammation and Thrombogenicity
in Atherosclerosis
J.F. Viles-Gonzalez, V. Fuster and J.J. Badimon
Plaque disruption and subsequent thrombus formation play
a critical role in the clinical manifestations of atherothrombosis.
Vulnerable lesions are characterized by the existence of core
rich in lipid, macrophages and tissue factor (TF). Plaque
disruption facilitates the interaction between flowing blood
with the inner components (TF) of disrupted atherosclerotic
lesions triggering the coagulation cascade. TF, thrombin,
platelets, fibrin and inflammatory cells are involved in this
process of acute thrombus formation. This pathologic process
is significantly accelerated by several "cardiovascular
risk factors" such as diabetes, smoking, dyslipemia,
etc.
We will review on the role of TF, plaque cell apoptosis and
blood thrombogenicity acting as a thread of inflammatory and
prothrombotic mediators. We will also review the role of activated
platelets as source for pro-inflammatory cytokines and enunciation
of thrombotic process. Overall, we will try to emphasize the
most recent understanding of the concepts involved in the
interaction between inflammation and coagulation within the
setting of atherothrombotic disease.
[Back to top]
Metabolic Syndrome and Diabetic Atherothrombosis:
Implications in Vascular Complications
P. Meerarani, J.J. Badimon, E. Zias, V. Fuster and P.R.
Moreno
Metabolic syndrome is characterized by the clustering
of a number of metabolic abnormalities in the presence of
underlying insulin resistance with a strong association with
diabetes and cardiovascular disease morbidity and mortality.
The disorder is defined in different ways, but the pathophysiology
is attributable to insulin resistance. An increased release
of free fatty acids (FFAs) from adipocytes block insulin signal
transduction pathway, induce endothelial dysfunction due to
increased reactive oxygen species (ROS) generation and oxidative
stress. Dyslipidemia, associated with high levels of triglycerides
and low concentrations of high density lipoproteins (HDLs),
contributes to a proinflammatory state. Inflammation, the
key pathogenic component of atherosclerosis, promotes thrombosis,
a process that underlies acute coronary event and stroke.
Tissue factor, a potent trigger of the coagulation cascade,
is increased in diabetes with poor glycemic control. Therapeutic
lifestyle changes (weight loss and physical activity) along
with pharmacological interventions are recommended to prevent
the complications of metabolic syndrome. In addition to statins,
metformin, blood pressure lowering medications, interventions
to increase HDLs are other important approaches to decrease
the risk of cardiovascular disease. Furthermore, the peroxisome
proliferator activated receptor (PPAR) - alpha and gamma agonists
are potent anti-inflammatory and anti-atherogenic agents that
could both improve insulin sensitivity and the long-term cardiovascular
risk.
In this review we focus on the molecular and pathophysiological
basis of metabolic syndrome, which augments diabetes (insulin
resistance) and the contribution of neovascularization in
the plaque progression in diabetes, leading to rupture and
coronary thrombosis.
[Back to top]
Molecular Determinants of Vascular Calcification:
A Bench to Bedside View
S. Dellegrottaglie, J. Sanz and S. Rajagopalan
Vascular calcification (VC) is an orchestrated event, evoking
the programmed process of the osteogenesis and triggered by
inflammatory cytokines active at vascular level. VC is a dynamic
process in which the vessel wall intima, media and also cardiac
valves may be involved. Intimal calcification is an endochondral
ossification process in which type II collagen is mineralized
by calcium deposition. In contrast, an intra-membranous ossification
process leads to medial calcification, while a dystrophic
calcification process is responsible for valvular calcification.
Mechanisms involved in VC may be summarized as: 1. Activation
of osteogenesis in the vessel wall, 2. Loss of inhibitory
factors, 3. Enhanced bone turnover, and 4. Abnormalities in
mineral metabolism.
The signaling axis constituted by osteoprotegerin (OPG), receptor
activator nuclear factor kB (RANK) and its ligand (RANKL),
along with the monocyte colony stimulating factor (M-CSF)
and the transcription factor core Binding protein (Cbfa-1),
play a pivotal role in the control of VC. In contrast, fetuin-A,
matrix G1a protein (MGP) and osteopontin (OPN) control the
inhibition of VC. In addition, abnormal mineral metabolism
with enhanced phosphates availability favors calcium deposition.
The inflammatory cytokines interleukin (IL-1) and tumor necrosis
factor (TNF)-α
enhance OPG and RANKL function in the vessel wall leading
to VC. VC is a controlled process, depending on the balance
between osteoblastic and osteoclastic influences and further
modulated by the influence of risk factors like diabetes,
smoking, age, hypertension and dyslipidemia. Recent advances
in diagnostic tools such as with multi-detector computed tomography
(MDCT) and electron beam computed tomography (EBCT), may help
diagnosis and delineation of VC in the clinical setting and
aid in understanding its prognostic value.
[Back to top]
Calcium Scoring and Contrast-Enhanced CT Angiography
J. Sanz, S. Dellegrottaglie, V. Fuster and S. Rajagopalan
Computed tomography (CT) technology has emerged as the
most promising imaging modality for the noninvasive evaluation
of the coronary circulation. Of the CT-based approaches, multidetector-row
computed tomography (MDCT) and to a lesser extent electron
beam computed tomography offer the potential of providing
not only data on the spatial extent and burden of coronary
calcium content, but also angiographic data, and plaque composition
characteristics with the potential for prediction of susceptibility
to future cardiovascular events. A number of studies have
now confirmed that CT-based assessment of the presence and
amount of coronary artery calcium provides incremental prognostic
information over traditional risk factors in patients with
coronary artery disease and can be employed to refine risk
stratification in both asymptomatic and symptomatic subjects.
With the advent of several recent advances in CT imaging,
it is now possible to provide high resolution (sub-millimeter,
isotropic voxels) images of the coronary arteries obtained
rapidly with iodinated contrast injected peripherally. MDCT
is currently the preferred modality for noninvasive contrast
angiography of the coronary arteries by most groups, with
a new generation of 64-slice scanners promising to further
improve the results of this technique. MDCT-derived angiographic
information in conjunction with coronary calcium scoring and
plaque characterization has the potential of replacing invasive
angiography, as it potentially could provide better global
assessment of risk.
[Back to top]
Plaque Imaging and Characterization Using Magnetic
Resonance Imaging: Towards Molecular Assessment
M. Sirol, V. Fuster and Z.A. Fayad
Identification of high-risk atherosclerotic lesions prone
to rupture and thrombosis may greatly decrease the morbidity
and mortality associated with atherosclerosis. High-resolution
magnetic resonance imaging (MRI) has recently emerged as one
of the most promising techniques for the non-invasive study
of atherothrombotic disease, as it can characterize plaque
composition and monitor its progression. The development of
MRI contrast agents that specifically target components of
the atherosclerotic plaque may enable non-invasive detection
of high-risk lesions. This review discusses the use of high-resolution
MRI for plaque detection and characterization and the potentials
of “Molecular Imaging” using a variety of molecules
present in atherosclerotic plaques that may serve as targets
for specific contrast agents to allow the identification of
high-risk atherosclerotic lesions in vivo. Ultimately,
such agents may enable treatment of “high-risk”
patients prior to lesion progression and occurrence of complications.
[Back to top]
Atherosclerosis Neovascularization and Imaging
K.R. Purushothaman, J. Sanz, E. Zias, V. Fuster and P.R.
Moreno
Neovascularization in atherosclerotic plaques is particularly
prominent in complicated lesions, and has been recently identified
as a marker of plaque vulnerability. This observation has
led to a growing interest in the development of imaging techniques
with the ability to visualize and quantify the extent of plaque
neovascularization. Such feature may play an important role
in identifying those lesions more prone to destabilization
and rupture, and in the guidance and monitoring of therapeutic
interventions. Several modalities have emerged as potential
candidates for imaging neovessels in atherosclerotic lesions.
They include magnetic resonance imaging, x-ray computed tomography,
positron emission tomography, single photon emission computed
tomography, ultrasound, or near-infrared optical imaging.
These techniques differ in their achievable spatial and temporal
resolution, availability, cost, reproducibility, degree of
intrusiveness, capability to image atherosclerotic plaques
in various vascular territories and ability to discern different
plaque components, specifically the presence of neovessels.
Molecular imaging, a rapidly evolving multidisciplinary field
devoted to the visualization of specific physiopathologic
processes at the cellular or molecular level, appears particularly
well suited for this purpose because of its ability to target
and visualize individual molecules specific to neoangiogenesis.
In this manuscript we will review current evidence on the
potential application of the various modalities, with a particular
emphasis in molecular imaging.
[Back to top]
Cardiac Biomarkers for the Prediction and Diagnosis
of Atherosclerotic Disease and its Complications
M.D. Weinberg, W.C. Hooper and G. Dangas
Inflammation has been implicated in all stages of cardiovascular
disease. This has driven a very fruitful search for new biomarkers,
which potentially can be used as tools in the diagnosis and
prognosis of atherothrombotic disease. While these new markers
might prove useful in predicting the onset of atherosclerosis
in healthy individuals, the utility of biomarkers in risk
assessment for events in those patients with established disease
and/or those with acute coronary syndrome requires further
work. Effective biomarkers must be standardized, logistically
simple to analyze, and clinically useful. Understanding what
impact sex, age, ethnicity, and comorbid conditions may have
on biomarkers is also of importance. Unfortunately, many of
the candidate markers have yet to satisfy these requirements.
[Back to top]
The Role of High-Density Lipoprotein Cholesterol in
the Prevention and Possible Treatment of Cardiovascular Diseases
B.G. Choi, G. Vilahur, D. Yadegar, J.F. Viles-Gonzalez and
J.J. Badimon
Despite significant progress in the management of atherosclerosis
and its resultant complications, cardiovascular disease remains
the principal cause of death in the world. The National Cholesterol
Education Project Adult Treatment Panel III (NCEP ATP III)
recognizes low levels of high-density lipoprotein cholesterol
(HDL) as a risk factor for coronary heart disease (CHD) and
high levels of HDL as a risk-reducing factor; however, the
elevation of HDL as a specific therapeutic target for the
prevention and treatment of CHD has yet to be accepted on
the same level as low-density lipoprotein (LDL)-reducing therapies.
Current HDL elevators including nicotinic acid, fibric acid
derivatives, peroxisome proliferator activated receptor (PPAR)
agonists and statins also affect other lipid constituents
which make interpretation of the clinical trials of these
drugs difficult in teasing out the independent effect of HDL
elevation. Ample laboratory investigation suggests that HDL
elevation would reduce atherosclerotic burden through multiple
independent mechanisms. In this review, we explore HDL biology,
its potential mechanisms in the treatment of atherosclerotic
disease, and promising new drugs with HDL-raising activity.
[Back to top]
Statin Therapy for Native and Peri-Interventional
Coronary Heart Disease
D.A. Smith and I. Galin
Atherosclerosis is a slow, complex process involving
many different cell types and their interactions producing
excessive oxidant stress, increased inflammation, abnormal
endothelium-dependent vasodilation, and localized increases
in thrombogenic and decreases in fibrinolytic factors. Numerous
factors incite these processes, but oxidized LDL particles
seem the most essential component of this pathologic cascade.
These oxidized particles set up a chain of biochemical events
eventually leading to clinical atherosclerotic events. Statins
have been shown to reduce such events by 40 to 50% when LDL
cholesterol is lowered to less than 80 mg/dL. But in-vitro
studies have shown that the provision of mevalonate, not cholesterol,
can result in reversal of some of the beneficial effects of
statins, suggesting that other mechanisms such as inhibiting
the formation of the isoprenoids, farnesyl pyrophosphate and
geranylgeranyl pyrophosphate, and thus prenylation of many
cell-signaling proteins may be important in the preventive
effects of statins. Clinically, these more rapid, non-lipid-altering
effects may be more apparent in acute coronary syndromes.
Now that we have more LDL-cholesterol lowering agents which
lower LDL-cholesterol without blocking HMG CoA reductase,
we may be better able to dissect and understand the importance
of these non-lipid-altering effects of statins in human disease.
[Back to top]
Antithrombotic Therapy
W.L. Duvall
Coronary heart disease is the leading cause of death in the
US and the industrialized world. Ever since DeWood in 1980
demonstrated that a thrombus was the primary event leading
to acute myocardial infarction and that they may subsequently
lyse, the mainstay of therapy for the past 25 years has been
antithrombotic therapy aimed at coronary thrombosis. There
have been numerous advances in the treatment of acute coronary
syndrome with antiplatelet, antithrombotic, and fibrinolytic
agents that have significantly reduced morbidity and mortality.
The role of various pharmaceutical agents in the different
phases of acute coronary syndrome is a complex and ever changing
field.
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