ABSTRACT-
Stroke is a brain injury where a sudden interruption of the blood supply in brain part and the brain does
not receive the enough blood flow due to which there is a lack of oxygen and glucose and without blood supply the brain
cells begin to die (cerebral infarction) and cause brain damage. So there is a need to understand the pathophysiology and
to effective biomarkers in acute ischemic stroke and may help to enhance the current clinical outcome of stroke. Various
biomarkers are associated with the pathophysiologic mechanism and they may help in stroke assessment, diagnosis,
prognosis or treatment. There is a higher rate of morbidity and mortality in stroke. Hence a better pharmacological
management is desired for the fast recovery and treatment from stroke. Thrombolytics, antihypertensive, anti-platelet
therapy, antioxidants, rehabilitation technique and their combinations e.g. Aspirin and clopidogrel, Aspirin and
dipyridamole, ramipril and telmisartan, IgG- glial cell-lined derived neurotropic factor (GDNF) and IgG – tumor necrosis
factor receptor(TNFR) etc. and various surgical treatment such as carotid endarterectomy, stereotactic radiosurgery,
hypothermia, revascularization of the blood supply, endovascular treatment of aneurysms and angioplasty and stenting of
vessels in the neck and brain are also required for the beneficial outcomes in future.
Key-words- Stroke, Biomarker, Pathophysiology, Combinational therapy, Surgical treatment
INTRODUCTION-
Stroke is a neurological disease which cause of disability
and death (1). The blood supply of brain in stroke is
obstructed because of ischemia and hemorrhage which
causes the brain dysfunctioning. Ischemia caused by
blockage in blood vessels via thrombosis and arterial
embolism vasoconstriction. In ischemia reduction in
sufficient blood flow to alter the normal cellular function (2).
Stroke has two major categories of brain ischemia one is
global-ischemia and other one is focal ischemia. In focal
ischemia models, the middle cerebral artery is occluded,
either temporarily (vessels are blocked up to 3 hrs) or
permanently (vessels) are blocked usually for one or more
days) to allow the reperfusion (3-4).
There are two types of risk factors for causing stroke one is
controllable risk factor includes high cholesterol, smoking
tobacco use, hypertension, diabetes, obesity blood disorder
and certain drugs (i.e., anticoagulant and birth control
pills). Rather than this uncontrollable risk factors include
age, gender, family history, transient ischemic attack (TIA)
artery abnormalities, fibro muscular dysplasia (5-6). So there
are some treatments available for stroke. Only tissue
plasminogen activator (tPA) as a drug for stroke treatment
approved by FDA which reopens the blocked blood vessels (7). Recovery and prevention of stroke a good pharmacological
management is required for better treatment which can
reduce the risk factors of recurrent stroke.
Figure 1: Types of stroke (3)
Mechanism of Ischemic Stroke-
Ischemic cerebrovascular disease is caused by embolism,
thrombosis and focal hypoperfusion, which leads to an
interruption or reduction in cerebral blood flow (CBF)
affect the neurological function (8). In adult the normal
range of CBF is 50-55ml/100g/min, the brain damage is
reversible and brain infarction occurs (9). The pathophysiology
of stroke is complex and involves various processes,
including energy failure, oxidative stress, excitotoxicity,
oxidative stress, inflammation distruption of the blood
brain barrier (BBB), apoptosis, adhesion molecules,
activation of glial cells and infiltration of leukocytes.
Figure 2: Major cellular patho-physiological mechanism of
ischemic stroke (4)
Excitotoxicity-
Excitotoxicity defines to sequences of events which are
induced by excessive accumulation of excitatory amino
acids which leads to toxic increases in intracellular calcium
ions
(10). After reduction or termination of CBF and energy
dependent Na
+-k
+-ATP enzyme fail due to reduced in
glucose dependent ATP generation, resulting in the flow of
various ions into the cell, including Na
+, Cl-, Ca2
+ and these
ions can interrupted by the overstimulation of 1-amino-3-
hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA),
N-methyl-d-aspartic acid (NMDA) and kinate – glutamate
type receptors, glutamate as major excitatory
neurotransmitter in brain, deposite in the extracellular space
in ischemia and activate its receptor and after activation
produces alteration in the intracellular ion concentration
including most calcium and sodium ions. These cells
become depolarized, which cause more Ca
2+ influx and
more glutamate release may result that acute swelling of
cells which ultimately causing cell death. Calcium as a
secondary messenger activates multiple signaling pathways
that lead to necrosis or apoptosis.
Oxidative Stress-
Neurons are mainly exposed to a base line level of
oxidative stress that includes exogeneous and endogeneous
sources, as are all in body cells. Oxidative stress occurs
when there is imbalance between production of free
radicals and endogeneous scavenging capacity of cellular
antioxidants
(11-12). Free radicals are those molecules with
one or more unpaired electrons and highly reactive which
can react with DNA, lipids and proteins that cause
dysfunction and damage. In stroke induced brain injury,
include superoxide anion (O
2), hydroxyl radical (OH·),
nitric oxide (NO) and hydrogen peroxide (H
2O
2). O
2 is
generated earliest, while OH· is the most toxic. In ischemic
stroke, superoxide anion initially generated radical through
various ways, including mitochondrial electron transport
process
(13), xanthine oxidase (XO) process which is to be a
major source for the generation of oxygen free radicals in
ischemia and reperfusion
(14,15) and metabolism of
arachidonic acid (AA) by the cyclooxygenase (COX)
pathways. H
2O
2 is formed by superoxide anion and it is the
sources of (OH·). NO is released from L-arginine by nitric
oxide synthases (NOS) which are calcium dependent. NO
can react with superoxide anion to produce peroxynitrite
(ONOO), and another highly toxic oxygen species
(16). On
the another hand, antioxidants like superoxide dismutase
(SOD), catalase (CAT) and glutathione peroxidase (GPX)
degrade superoxide anion into H
20
2, additionally transfer
H
2O
2 into H
2O. Additionally to these defenses, the brain is
vulnerable to oxidative stress resulting from ischemia and
reperfusion.
Increase calcium influx which disrupts mitochondrial
integrity from which Cytochrome C is released to trigger
apoptosis that cause varying degrees of damage, ultimately
cause cell death
(17).
Figure 3: Necrosis occurring due to oxidative stress at
cellular level (4)
Inflammation-
Various cell types contribute to post-ischemic
inflammation, including endothelial cells, microglia and
neurons and astrocytes
(18). The major elements in an
inflammation reaction involve signaling molecules,
inflammatory cells, adhesion molecules and transcriptional
regulators. Reperfusion occur and upregulated adhesion
molecule which cause release of cytokines to cause
inflammation which leads to release of free radicals like
ROS and cause death. Oxygen free radical, increasing
amount of calcium and ischemia itself can activate
astrocytes and microglia to produce pro-inflammatory
cytokines like tumor necrosis factor-1(TNF-a),
interleukin-1 (1L-1) and interleukin- 1ß (1L-1ß) as well as
Neuroprotective factors, such erythropoietin,
metallothionein-2 and TGFb1
(19). Most of these
cytokines can induce the production of some adhesion
molecules such as selectins such as (E-selectins,
P-selectins), immunoglobulin superfamily (intercellular
adhesion molecule-1, vascular endothelial adhesion
molecule-1) and integrins. Meanwhile interleukin-8 (1L-8),
monocyte adhesion protein chemistry -1(MCP-1) and other
chemokines plays a very important role in the migration of
inflammatory cells. By the help of matrix metalloproteinase
(MMP), the extracellular matrix is broken down and
inflammatory cells infiltrate the brain parenchyma. After
4-6 hr onset of ischemia circulating leukocytes reach the
penumbra.
The inflammatory injury is induced by various molecules
such as cell adhesion molecules (integrins, selectins and
immunoglobulins), chemokines (CINC, MCP-1) cytokines
(IL-1, IL-6, TNF-a, TNF-ß), Inducible neuronal nitric
oxide synthase (iNOS) which produced by endothelial
cells, microglial cells, leukocytes and activated asrtocytes
and these all are contributed to the irreversible damage.
The assignment of neutrophils to ischemic brain begins
with rolling of neutrophil on activated endothelial blood
vessels walls then mediated by selectins and followed by
neutrophil adherence and activation which mediate by
integrins and immunoglobulins and when neutrophils
immigrate into the cerebral parenchyma, that causes blood
brain barrier BBB disruption.
After reperfusion the assignment of neutrophils can prevent
complete restoration of cerebral blood flow and obstruct the
microcirculation. If once neutrophils penetrate into the
ischemic brain they release of free radicals and proteolytic
enzymes which cause tissue damage.
Chemokines and cytokines are also contributed to brain
injury. In cerebral endothelia cells both il-1 and TNF-a
induces adhesion molecule expression and initiate the
accumulation of neutrophils and transmigration. In addition
TNF-a disrupts the BBB blood brain barrier, stimulates the
production of acute-phase protein and also stimulates the
induction of other inflammatory mediators while TNF-ß
plays an important role in neuroprotective in pathogenesis
of stroke. Neutrophills are the first leukocyte subtype
involved in inflammation
(20).
Blood Brain Barrier (BBB) Dysfunction-
Disruption of blood brain barrier in acute ischemic stroke
varies considerably from 15 - 66%
(21). The major reasons
that contribute to the damage of the BBB in acute ischemia
and reperfusion injury are free radicals and inflammation.
Matrix metalloproteinase MMPs and serine proteases are
essential breakdown of the extracellular matrix around
cerebral blood vessels and neurons, and there action leads
to the disruption of BBB, brain edema, hemorrhage, and
cell death. Therefore MMPs are thought to be direct factors
which lead to brain damage
(22). BBB damage mentioned to
be a biphasic in ischemic stroke
(23).
After 2 hr ischemia onset, BBB gets a transient opening
that may results from oxidative stress which trigger
activation of MMP-9
(24) and MMP-2
(25).
Apoptosis-
There are two forms of cell death, necrosis and apoptosis.
Many brain cells in ischemic injury undergo apoptosis,
which in contrast to necrosis which is a relatively orderly
process that allows cell to die with minimal damage and
distruption to neighboring cells
(26). There is minor
inflammation or release of genetic material
(27). They are
potentially recoverable for some time after the onset of
stroke. For activation of apoptosis caspase-dependent is an
important mechanism. It includes the intrinsic pathway,
which is initiated by release of cytochrome C by
mitochondria and resulted in activating caspase -3 and the
extrinsic pathway which triggered by activation of cell
surface death receptors and resulting in caspase-8
(28).
Biomarkers in Acute Ischemic Stroke-
During ischemic stroke, ideal biomarkers should possess
characteristics that include sufficient selectivity, reactive,
predictable clearance, stable and primarily release shortly
after infarction, potential for risk assessment and guidance
therapies, and ability to be quantitatively and rapidly
measured by cost effective methodologies
(29). Various
novel biomarkers of cerebral injury which is related to the
pathophysiology reviewed above, and in clinical scenarios,
they may have applications in stroke prediction,
assessment, diagnosis, prognosis or treatment.
Coagulation/thrombosis biomarkers-
In mostly cases, the main cause of acute ischemic stroke is
atherothrombosis of large cervical or intracranial arteries,
or embolism from heart or cerebropetal arteries
(30). In this
condition, molecules involved in coagulation or thrombosis
are associated with ischemic stroke, including fibrinogen,
von Willebrand factor (vWF), which is reported in recent
years. In prediction value, fibrinogen was reported by
Fibrinogen Studies Collaboration that plasma fibrinogen
level was significantly related with coronary heart
diseases(CHD), stroke and other causes of vascular and non
vascular mortality
(31), and by community- based study in
Taiwan which is 72% increase(hazard ratio, 1.72; 1.02 to
2.90) in ischemic stroke that was observed for individuals
with fibrinogen =8.79µmol/L compared with those
?7.03µmol/L, suggested fibrinogen is independently
predicted future ischemic risk
(32). And also D-dimer and
vWF are reported to be related with increased risk of stroke
in older men, and these associations were independent of
inflammation for D-dimer, this is a significant predictor of
stroke in hypertensive men
(33). Laskowitz et al
(34) reported
a five panel biomarkers (S100B, vWF, B-type NGF, MMP9
and MCP-1) can diagnose the stroke with 93% specificity
and 92% sensitivity. D- dimer is to distinguish
cardioembolic stroke from some other subtypes of ischemic
stroke
(35). Combined of D-dimer with D-dimer/fibrinogen
ratio, CRP and erythrocyte sedimentation and it can be
separate large vessel from cardioembolic stroke
(36). So it is
reported that plasma D-dimer level on admission is
significantly associated to infarction volume and functional
outcome in cardioembolic stroke in non-valvular arterial
fibrillation patients
(37).
Biomarkers in Oxidative Stress-
Science direct measurement of reactive oxygen species
(ROS) in brain is difficult in humans because of their
endogenous antioxidants, transient nature and limitation of
measurement as well as several biological substances
whose chemical structure has been modified by free
radicals have been investigated as potential indirect
biomarkers in oxidative stress.
Endogenous Antioxidants-
Endogenous antioxidants have enzymatic (CAT, GPX and
SOD) and non enzymatic antioxidants (retinol, uric acid,
ascorbic acid, caroteniod and tocopherol) which consists of
the cellular protective antiradical mechanism.
Antioxidants catalase (CAT) and glutathione peroxidase
(GPX) in a safe way can dispose H
2O
2 to protect neural
cells from oxidative stress. In ischemic patients clinical
researchers showed that CAT and GPX activity were
significantly higher as compared to controls
(38-39) and CAT
can be considered as adequate marker for positive outcome
(39). And on the other hand, GPX activity found to be
significantly lower in ischemic patients compared with
controls
(40, 41). So this debate may result by the degree of
damage by ROS, since antioxidant enzymes might be
induced by oxidative stress and their activity/level may
increase or else consumed (thus decreasing their levels and
activity
(42).
In stroke, SOD is the most studied antioxidant enzyme
whose changes of activity/concentration in blood were also
extremely disputed. Studies have found that the SOD
activity in patient’s plasma
(39-40), serum
(43) and red blood
cells
(41) to be significantly lower than control group, while
other found that the SOD activity in red blood cells have a
contrary result
(44). Similarly, in ischemic patients blood
concentration of SOD is controversial. So, this debate may
because the three different isoforms of superoxide
dismutase (CuZnSOD, MnSOD and EC-SOD), and the
different analysis methods
(40), so most of the studies
suggested that the SOD levels and concentration has a
significant correlation with infarct size and neurological
deficit.
Biomarkers of Oxidative Product-
DNA, proteins and lipids can be damage by ROS and many
metabolites produced during this process can be measured
in the serum.
Biomarkers of lipid peroxidation-
The brain cellular membrane lipids extremly rich in rich in
polyunsaturated fatty acid side chains and this is highly
prone to free radical attack that results in lipid peroxidation
include biomarkers such as thiobarbituric acid-reactive
substances (TBARs), malondialdehyde (MDA), lipid
peroxides (ROOH) and F2-isoprostanes(F2IPs). The
plasma concentration of TBARs, MDA and lipid
peroxidaton are mostly used biomarkers of oxidative stress.
In cerebral ischemia patients many studies demonstrated
that concentration of TBARs and MDA are higher than in
controls, and they are correlated with infarct size, patient’s
and clinical stroke severity
(38,45-46). However, insufficient
specificity of both MDA and TBARs for measurement of
lipid perpxidation, because MDA can present from both
lipid peroxidation products and also from endoperoxides
degradation
(42), and when reacting with TBA, other
molecules can depletes MDA which increases the amount
of MDA to react with TBA
(47).
Prostaglandin–like products (F2IPs) of non-cyclooxygenase
free radical induced peroxidation of arachidonic acid and
because of its good stability, sensitivity and specificity they
are reliable marker. They can be detecting in plasma and
urine
(). Kelly et al. reported that the plasma concentration
of F2IPs were increased primarly in ischemic stroke
patients as compared to control
(48).
Biomarkers of DNA oxidation-
The product of DNA oxidation is 8-hydroxy-2’-
deoxyguanosine (8-OHdG) has been mostly used as
excellent biomarkers of oxidative stress
(49). An animal
study established that the plasma concentration of 8-OHdG
were increased and significantly related to brain content of
8-OHdG
(50). In patients with high risk of vascular
recurrence or vascular death it could be useful to identify
and to determine some particular atherosclerotic plaques
characterstics
(51).
Biomarkers of protein oxidation-
In humans there is an in sufficient studies in protein
oxidation biomarker, however, a study on patients with
Alzheimer’s diseases and vascular dementia has established
that estimation the protein carbonyl and the dityrosin
contents of immunoglobulin G (IgG) can be executable not
only for its delicate to dietary antioxidant supplementation
and a associated long –half-life of 15 days that make IgG a
satisfactory marker of oxidative stress
(52).
Biomarkers of inflammation-
Serum level of IL-1ß, IL-6, IL-8, IL-17, TGF-ß, ICAM-1,
VCAM1, P-selectin, E-selectin, L- selectin, MCP-1 and
TNF-a has shown ascent, compared to controls
(53). In
ischemic stroke patients, the serum concentration of IL-6,
VCAM-1, BDNF, IL-1ß, TNF-a, ICAM-1 and MMP-2/9
were found significantly different when compared to other
neurological diseases and many of them are correlated with
infarct size and neurological deficit such as MMP-2/9,
BDNF, TNF-a, ICAM-1
(54).
In inflammatory reaction, TNF-a is a major cytokine with a
myriad of effects
(55) reported that inhibition of production
of MMPs by TNF-a and also reduce the brain edema in
ischemia. While on contrary others shown that TNF-a
activated the production of MMPs and increases the
inflammatory injury
(56). Different results conclude a
complex role of TNF-a in inflammatory mechanisms.
C-reactive protein (CRP) as an important indicator of
inflammation has been studied extensively. In ischemic
stroke patients increased the concentration of high
sensitivity C-reactive protein (hsCRP) has been observed
(57). CRP concentration is correlated with infarct size
volume and neurological deficit in ischemic stroke, and
has a potential prognostic value for poor outcome
(58).
Management of Ischemic Stroke-
The central goal of therapy in acute ischemic stroke is to
preserve tissue in the ischemic penumbra, where perfusion
is decreased but enough to stave off infarction.
Administration of intravenous (IV) recombinant
tissue- type plasminogen activator (rt-PA) and
intra-arterial approaches, attempt to establish
revascularization therefore, penumbra cells can be rescued
before irreversible injury occurs. Many surgical and
endovascular techniques have been studied in the
treatment of acute ischemic stroke
(59).
Supplying vessels assessment and brain imagining were
required to determine the cause and type of stroke and it
may also help to estimation the site and cause of arterial
obstruction
(60). Brain ischemia and myocardium are shows
common pathological changes therefore, the current
therapy are given such as anti-platelet therapy,
anticoagulant therapy, thrombolytic therapy,
hypercholesterolemia, clot disruption, hypertension
treatment therapy, antioxidant therapy and herbal drug
therapy. Recovery and prevention of stroke is a good
pharmacological management for better treatment which
can reduce the risk factor of recurrent stroke. Some surgical
techniques are also used to treat ischemic stroke. Different
therapies of stroke treatment are illustrated in Table 1.
Thrombolytic therapy-
Thrombolytic drugs burst the blood clots or dissolve blood
clots and this process known as thrombolysis. It is also
known as clot busting
(78). If the patients have acute
ischemic stroke, the risk of bleeding can increased and
pretreated with antiplatelet or anticoagulant drugs
(79).
Thrombolytics drugs dissolve the blood clots by activating
the plasminogen which converts into plasmen which is
proteolytic enzyme which break or degrade thrombus by
breaking fibrinogen, fibrosis monomers and cross-linked
fibrin molecules, that is present in thrombus
(61).
Table 1: Some combinational therapies stroke of ischemic stroke
Stroke Treatment | Combinational therapies |
Thrombolytic therapy | Plasminogen activators e.g- Altepase,
Streptokinase,
Reteplase, Tenecteplase (61-64) |
Antiplatelet therapy | Aspirin, Triflusal, Ticlopidine,
Clopidogrel (65-69) |
Hypercholesterolemia | Statins (70) |
Hypertension
treatment |
Angiotension type-1 receptor blockers,
a-blockers (71) |
Antioxidant therapy | Melatonin, Vitamin E, Glutathione,
Superoxide dismutase(SOD), Catalase,
Tocopherol, Ascorbic acid (70,72-73) |
Combinational
therapy |
(Clopidogrel + aspirin), (Aspirin +
dipyridamole), (Telmisartan + ramipril) (74-76) |
Rehabilitation | Stroke rehabilitation program,
Outpatient rehabilitation for stroke,
Muscle relearning (77) |
Anticoagulant therapy | Heparin, Warferin (59) |
Surgical treatment | Carotid Endarterectomy, Stereotactic
Radiosurgery, hypothermia, Endovascular
treatment, Revascularization of blood
supply (59) etc.
|
Streptokinase (SK)-
It is plasminogen activators which formed the
SK/Plasminogen complex. It is CS-hemolytic streptococci
group which derived protein that showed significant rates
of ischemia and systemic hemorrhage
(62).
Because of drug failure or trail design failure, SK
(Streptokinase) trials was unsuccessful in stroke but at low
dose it was proven that in a properly trail it may have
beneficial effects on stroke when other alternative will not
present
(80-81).
Alteplase (Recombinant Human Tissue Type
Plasminogen Activator rtPA)-
Alteplase is a serine protease. It have plasma half-life of 3.5
min. it maintained the clump penetration because it highly
binds with surface fibrin and detention the restoration flow
that increases the risk of recurrent of occlusion.
The rtPA have some neurotoxic properties including
activation of metalloproteinase that may increase the
permeability of Blood- Brain –Barrier which leads to
cerebral hemorrhage and edema. rtPA is used in the first
line therapy of acute ischemic stroke. rtPA shows beneficial
effect if it was administer within 3hr of the initiation of
stroke but after 3hr administer of rtPA shows lesser
beneficial effects
(82).
Antiplatelet therapy-
Antiplatelet drugs are those that inhibit the thrombus
formation and decreases platelet aggregation in blood.
Aspirin-
Aspirin is a non-steroidal anti-inflammatory drug which is
cyclo-oxygenase inhibitors. It inhibit the protection of
thromboxane, which in normal condition binds platelet
molecules with each other and to grow a patch over
damaged blood vessels walls. In ischemic stroke patients,
low dose of aspirin (50-325mg/kg) avoid the risk of motion
or drift (motility) and ischemic injuries
(74) and higher dose
of aspirin has some undesirable side effects like
gastrointestinal ulcers, tinnitus and stomach bleeding
(83).
Triflusal-
Triflusal (2-acetoxy-4-trifluoromethylbenzoic acid) is used
to decrease the aggregation of platelet in blood. It inhibits
COX1 and COX2. The active metabolite (2-hydroxy-4-
trifluromethylbenzoic acid) HTB of triflusal hydrolyze
immediately when triflusal administer orally and HTB have
power to cross the blood brain barrier (BBB) and it has
been recently reported in healthy volunteers
(84). It reduces
the hemorrhagic complications and is well tolerated as
compared to aspirin
(66).
Adenosine diphosphate receptor inhibitors
Prasugrel-
Prasugrel is a platelet aggregation inhibitor
(67). Recently
prasugrel was examined as new P2Y12 antagonist receptor
which can be used in the treatment of atherothrombosis in
patients. In the case of higher bleeding rates, the clinical
benefit of prasugrel was higher than clopidogrel. Prasugrel
needs to biologic conversion to active metabolites and
shows the therapeutic action because prasugrel is a
prodrug. It inhibits the ADP- induced platelet aggregation
and produce greater effects than clopidogrel
(85).
Ticagrelor-
Ticagrelor is an inhibitor of platelet aggregation. It
antagonizes the adenosine diphosphate (ADP) P2Y12
receptor on platelet irreversibly. It shows beneficial effects
in ischemic stroke patient
(86-87). It shows the platelet
reactivity and produce beneficial effects in ischemic stroke
(69).
Hypercholesterolemia Treatment-
Increases the cholesterol or plaque in the arteries block the
normal blood flow to the brain and causes stroke and also
the increase risk of heart diseases and atherosclerosis.
Current studies demonstrate that the statins as re-educates
inhibitors significantly decreases the risk of ischemic
stroke. Statins have various mechanisms to decrease the
risk of stroke, like degradation of plaque, by enhancing the
bioavailability of nitric oxide, by homeostasis and by
decreasing the low density lipoprotein cholesterol
(70).
Hypertension Treatment-
Prevention of secondary stroke, blood pressure control will
be required. It can control the hypertension by giving the
combination therapy. Recent studies reported that the new
hypertensive drugs (angiotensin type-1 receptor blockers,
a-blockers, calcium channel blockers) were more effective
in the prevention of stroke then older class drugs (diuretics,
ß- blocker)
(71).
Antioxidant therapy-
Oxidative stress occurs when an imbalance between the
production of free radical and defence power of cell against
free radicals in biological system. Increases the production
of reactive oxygen species (ROS) after brain injury and it
causes cellular damage (i.e. lipids, nucleic acids and
proteins) by several molecular pathways which leads to
cause cell death
(88-89). So antioxidants are used for
preventing or reducing the oxidative stress and reactive
oxygen species and it shows beneficial effects in cerebral
injury
(90-91). Because of their physical properties such as
water solubility (e g. Vitamin C) or lipid solubility
(e g. vitamin E) there are several antioxidants, which
crosses the BBB blood brain barrier. In the treatment of
stroke and stroke related oxidative stress antioxidants
shows neuroprotective effect
(92).
Superoxide dismutase-
They are enzymes which contain antioxidant properties but
have undesirable results in experimental stroke models.
Therefore, synthetic SOD/catalase, newly reported
EUK-134 was examined that shows cytoprotective
properties and also shows SOD properties. It shows
positive effect in the stroke patients when it significantly
decreases infarct size of brain, even after the ischemia
(93).
Glutathione (GSH)-
Glutathione prevent damage caused by reactive oxygen
species such as peroxides and free radicals due to the
presence of antioxidant properties
(94). According to
preclinical studies, glutathione mono-ethyl ester exhibit
neuroprotective effect and it useful in the cerebral ischemia
treatment. Glutathione reduces infarct size as defensive
antioxidant of cells
(73).
Scavenging of free radicals-
The antioxidant compounds have particularly thiols, such
as lipoic acid and precursors of glutathione which shows
antioxidant effect by hydroxyl radicals and scavenge
singlet oxygen. Vitamin E and C also work as scavenging
that increases the concentration of glutathione. A recent
study reported that N-acetylecysteine (NAC) administration
protects the brain from injury of free radical with the
effective therapeutic window after reperfusion and shows
neuroprotective effect
(95). Ginkgo biloba (EGb) and
a-lipoic acid (LA) both have an antioxidant action which
reduces free radical and increases the cerebral blood flow
and showed recently in study have neuroprotective effects
(96).
Vitamin E-
It is a fat-soluble vitamin and as an antioxidant. It stops the
formation of reactive oxygen species when fat undergoes to
oxidation
(72).
Ascorbic acid- It is a dietary supplement and prevents stress-induced
memory impairments and reduces oxidative stress. Vitamin
C and ascorbic acid cannot cross the blood brain barrier
(BBB) but when it oxidized, produces dehydroascorbic acid
which crosses the blood brain barrier and it is useful in the
stroke.
Xanthine oxidase inhibitor-
Uric acid concentration in blood increased shows the
increased xanthine oxidase activity and increase oxidative
stress that cause high level of damage. Xanthine oxidase
inhibitor alone or with drugs such as allopurinol,
oxypurinol and febuxostat shows a good therapeutic
approach for circulating uric acid concentration.
Nitric oxide synthases-
Nitric oxide (NO) is produces in brain. NO is an
intracellular messenger which attempt as mediator of cell
death in normal condition but it does not causes any
noxious while as its overproduction which causes ischemia.
So in the treatment of stroke selective nitric oxide inhibitor
can be used.
Combination therapies-
When the drugs were given alone sometime they shows
pharmacological effects but in some cases like in stroke,
alone drugs effects may be not sufficient for the treatment
of the diseases. Therefore, combinations drugs can produce
optimize effect. Previously some drugs like aspirin were
studied as an antiplatelet agent, who was widely used for
the prevention of stroke. Alone aspirin (25mg) according to
the trial reduces 15% risk of secondary stroke and in
combination with dipyridamole (200mg bid) will reduce
37% risk by various mechanism of action.
A combination treatment was investigated in middle
cerebral artery occlusion (MCAO) model with blood brain
permeability. In study the IgG- tumor necrosis factor
receptor (TNFR) and IgG- glial cell line-derived
neurotrophic factor (GDNF) fusion protein were used,
where TNFR and GDNF were fused with the chain of a
chimeric monoclonal antibody (MAb) which was opposed
to the mouse transferring receptor (TfR). The cTfRMAb-
GDNF fusion protein alone reduces 30% in cortical stroke
volumes and 25% reduces in hemispheric stroke volumes.
But when it was treated with combination form with the
cTfRMAb-GDNF and cTfRMAb-TNFR fusion proteins
which reduces 69%, 54% and 30% in hemispheric, cortical
and subcortical stroke volumes
(97). In animal study
examined that the combination therapy of angiotensin
converting enzyme inhibitor and angiotensin receptor
blockers (ARBs) shows better results in the treatment of
stroke. In better stroke treatment the ramipril/telmisartan
combination can give better BP control and greater
cardio-renal protection then alone treatment
(76).
Rehabilitation-
Rehabilitation describes specialized health care dedicated
to improving, maintaining or restoring physical strength,
cognition and mobility with maximized results. It involves
in various stroke patient mainly focused to improve quality
of daily life. Rehabilitation means to help people gain
greater independence after illness, surgery or injury
(77).
Figure 4: Rehabilitation
Surgical Treatment-
Various new surgical methods for stroke patients with
arteriovenous malformation and aneurysms: are offered like
stereotactic microsurgery, hypothermia and cerebral
revascularization and with this interventional
neuroradiology and stereotactic radiosurgery are also
offered.
Carotid Endarterectomy-
This technique is used to treat or remove atherosclerotic
plaque from the carotid artery when the vessel is blocked.
For several patients with minor strokes or TIAs this
technique has been recently proven and for preventing
future strokes this method (carotid endarterectomy) is
highly beneficial.
Stereotactic Radiosurgery for Arteriovenous
Malformation (AVMs)-
The procedure of stereotactic radiosurgery is generally
observed on an outpatient basis. This technique as
stereotactic microsurgery to identify the exact or precise
location of the AVM and if once located the AVM
obliterated by focusing a beam radiation which cause it to
clot and disappear then. Normal brain tissue is not affected
due to the precision of this technique.
Hypothermia-
There is a minor risk that the patient may have stroke while
on the operating table during the surgical treatment of
AVMs and aneurysms, so Stanford physicians are using a
hypothermia technique (cooling of the body) which are
used to prevent the stroke during the surgical treatment of
aneurysms and AVMs. Cardiopulmonary bypass machine
special equipment which are used to completely shunt
blood flow away from the brain while the body is placed
under the deep hypothermia.
Revascularization of the blood supply-
To treating the blocked cerebral arteries or aneurysms,
revascularization surgical techniques are used. This method
is providing a new way (route) of blood to the brain by
grafting other vessel to cerebral artery.
Endovascular Treatment of Aneurysms-
Endovascular treatment of aneurysms is known as a new
interventional neuroradiologic technique that is beneficial
for patients with serious medical condition who are
inefficient to sustain the stress of surgery. Stanford
established Platinum coils which are guided into the
aneurysms via a catheter that creating a clot that effectively
closes the aneurysm off from surrounding circulation and
preventing the future hemorrhagic stroke risk.
Angioplasticity and Stenting of Vessels in the Neck
and Brain-
Cerebral angioplasticity is similar to the cardiology
procedure which is mostly used to open the partially
blocked vertebral and carotid arteries in the neck as well as
blood vessels within the brain
(59).
SUMMARY-
The present days stroke is a extremly prevalent health
problem and to treat or prevent the stroke, completely
desire to understand the pathophysiology that can help to
improve the current clinical conditions of stroke and the
biomarker reflecting relevant events would also be of great
use in the ischemic cascade. By the use of marker in the
detection of stroke may require capturing all processes
underlying the ongoing ischemic event. A stroke can be
diagnosed by the various symptoms including sudden
numbness, severe headache, speech difficulty, face
dropping. So for the prevention and better treatment of
ischemic stroke there are multiple choices are provided
such as thrombolytics therapy, antioxidant, hypertension,
anticoagulant therapy, rehabilitation technique also and
various surgical treatment including such as carotid
endarterectomy, stereotactic radiosurgery, hypothermia,
revascularization of the blood supply, endovascular
treatment of aneurysms and angioplasty and stenting of
vessels in the neck and brain are also required for the better
treatment of ischemic stroke. There are such combination
therapy are also required in recent years for better
management that improved the stroke. Combination
therapy e.g. Aspirin and clopidogrel, Aspirin and
dipyridamole, ramipril and telmisartan, IgG- glial cell-lined
derived neurotropic factor (GDNF) and IgG- tumor
necrosis factor receptor (TNFR) shows the increased
benefit ratio in stroke patients.
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