create abstract for below information - Introduction:
GUILLAIN BARRE SYNDROME: Guillain-Barre (gee-YAH-buh-RAY) syndrome is a rare disorder in which your body's immune system attacks your nerves. Weakness and tingling in your hands and feet are usually the first symptoms.
These sensations can quickly spread, eventually paralyzing your whole body. In its most severe form Guillain-Barre syndrome is a medical emergency. Most people with the condition must be hospitalized to receive treatment.
Symptoms: Guillain-Barre syndrome often begins with tingling and weakness starting in your feet and legs and spreading to your upper body and arms. Some people notice the first symptoms in the arms or face. As Guillain-Barre syndrome progresses, muscle weakness can turn into paralysis.
Signs and symptoms of Guillain-Barre syndrome may include:
•	A pins and needles sensation in your fingers, toes, ankles or wrists
•	Weakness in your legs that spreads to your upper body
•	Unsteady walking or inability to walk or climb stairs
•	Difficulty with facial movements, including speaking, chewing or swallowing
•	Double vision or inability to move the eyes
•	Severe pain that may feel achy, shooting or cramplike and may be worse at night
•	Difficulty with bladder control or bowel function
•	Rapid heart rate
•	Low or high blood pressure
•	Difficulty breathing
People with Guillain-Barre syndrome usually experience their most significant weakness within two weeks after symptoms begin.
Risk factors: Guillain-Barre syndrome can affect all age groups, but your risk increases as you age. It's also slightly more common in males than females.
Guillain-Barre syndrome may be triggered by:
•	Most commonly, infection with campylobacter, a type of bacteria often found in undercooked poultry
•	Influenza virus
•	Cytomegalovirus
•	Epstein-Barr virus
•	Zika virus
•	Hepatitis A, B, C and E
•	HIV, the virus that causes AIDS
•	Mycoplasma pneumonia
•	Surgery
•	Trauma
•	Hodgkin's lymphoma
•	Rarely, influenza vaccinations or childhood vaccinations
•	COVID-19 virus
•	COVID-19 Johnson & Johnson and AstraZeneca vaccine.
Complications:
Guillain-Barre syndrome affects your nerves. Because nerves control your movements and body functions, people with Guillain-Barre may experience:
Breathing difficulties: The weakness or paralysis can spread to the muscles that control your breathing, a potentially fatal complication. Up to 22% of people with Guillain-Barre syndrome need temporary help from a machine to breathe within the first week when they're hospitalized for treatment.
Residual numbness or other sensations: Most people with Guillain-Barre syndrome recover completely or have only minor, residual weakness, numbness or tingling.
Heart and blood pressure problems: Blood pressure fluctuations and irregular heart rhythms (cardiac arrhythmias) are common side effects of Guillain-Barre syndrome.
Pain: One-third of people with Guillain-Barre syndrome experience severe nerve pain, which may be eased with medication.
Bowel and bladder function problems: Sluggish bowel function and urine retention may result from Guillain-Barre syndrome.
Blood clots: People who are immobile due to Guillain-Barre syndrome are at risk of developing blood clots. Until you're able to walk independently, taking blood thinners and wearing support stockings may be recommended.
Pressure sores: Being immobile also puts you at risk of developing bedsores (pressure sores). Frequent repositioning may help avoid this problem.
Relapse: A small percentage of people with Guillain-Barre syndrome have a relapse, experiencing muscle weakness even years after the symptoms ended.
 Local (normal) Treatment:
There's no cure for Guillain-Barre syndrome. But two types of treatments can speed recovery and reduce the severity of the illness:
Plasma exchange (plasmapheresis): The liquid portion of part of your blood (plasma) is removed and separated from your blood cells. The blood cells are then put back into your body, which manufactures more plasma to make up for what was removed. Plasmapheresis may work by ridding plasma of certain antibodies that contribute to the immune system's attack on the peripheral nerves.
Immunoglobulin therapy: Immunoglobulin containing healthy antibodies from blood donors is given through a vein (intravenously). High doses of immunoglobulin can block the damaging antibodies that may contribute to Guillain-Barre syndrome. These treatments are equally effective. Mixing them or administering one after the other is no more effective than using either method alone.
You are also likely to be given medication to:
Relieve pain, which can be severe
Prevent blood clots, which can develop while you're immobile
People with Guillain-Barre syndrome need physical help and therapy before and during recovery. Your care may include:
Movement of your arms and legs by caregivers before recovery, to help keep your muscles flexible and strong.
Physical therapy during recovery to help you cope with fatigue and regain strength and proper movement.
Training with adaptive devices, such as a wheelchair or braces, to give you mobility and self-care skills.
Background:
Guillain-Barré syndrome (GBS) can be described as a collection of clinical syndromes that manifests as an acute inflammatory polyradiculoneuropathy with resultant weakness and diminished reflexes. With poliomyelitis under control in developed countries, GBS is now the most important cause of acute flaccid paralysis. (See Clinical Presentation.)
Although the classic description of GBS is that of a demyelinating neuropathy with ascending weakness, many clinical variants have been well documented in the medical literature, and variants involving the cranial nerves or pure motor involvement and axonal injury are not uncommon. (See Pathophysiology.)
Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) is the most widely recognized form of GBS in Western countries, but the variants known as acute motor axonal neuropathy (AMAN), acute motor-sensory axonal neuropathy (AMSAN), and Miller-Fisher syndrome also are well recognized.
Based on a clinical spectrum of symptoms and findings, it is widely believed that strictly defined subgroups of GBS exist. However, these subgroups are not easily distinguished.
GBS remains a diagnosis made primarily through the assessment of clinical history and findings (see Clinical Presentation). Serum autoantibodies are not measured routinely in the workup of GBS, but results may be helpful in patients with a questionable diagnosis or a variant of GBS (see Workup).
Approximately one third of patients require admission to an intensive care unit (ICU), primarily because of respiratory failure. After medical stabilization, patients can be treated on a general medical/neurologic floor, but continued vigilance remains important in preventing respiratory, cardiovascular, and other medical complications. Treatment with intravenous immunoglobulin (IVIG) or plasma exchange may hasten recovery. After discharge, outpatient physical therapy and occupational therapy may be beneficial in helping patients with GBS to regain their baseline functional status.
Historical background:
In 1859, Landry published a report on 10 patients with an ascending paralysis. Subsequently, in 1916, 3 French physicians (Guillain, Barré, and Strohl) described 2 French soldiers with motor weakness, areflexia, cerebrospinal fluid (CSF) albuminocytologic dissociation, and diminished deep tendon reflexes. The identified syndrome was later named Guillain-Barré syndrome. Historically, GBS was a single disorder; however, current practice acknowledges several variant forms.

Pathophysiology:
GBS is a postinfectious, immune-mediated disease. Cellular and humoral immune mechanisms probably play a role in its development. Most patients report an infectious illness in the weeks prior to the onset of GBS. Many of the identified infectious agents are thought to induce production of antibodies that cross-react with specific gangliosides and glycolipids, such as GM1 and GD1b, that are distributed throughout the myelin in the peripheral nervous system.
The pathophysiologic mechanism of an antecedent illness and of GBS can be typified by Campylobacter jejuni infections. The virulence of C jejuni is thought to be based on the presence of specific antigens in its capsule that are shared with nerves.
Immune responses directed against lipopolysaccharide antigens in the capsule of C jejuni result in antibodies that cross-react with ganglioside GM1 in myelin, resulting in immunologic damage to the peripheral nervous system. This process has been termed molecular mimicry. 
Pathologic findings in GBS include lymphocytic infiltration of spinal roots and peripheral nerves (cranial nerves may be involved as well), followed by macrophage-mediated, multifocal stripping of myelin. This phenomenon results in defects in the propagation of electrical nerve impulses, with eventual absence or profound delay in conduction, causing flaccid paralysis. Recovery is typically associated with remyelination.
In some patients with severe disease, a secondary consequence of the severe inflammation is axonal disruption and loss. A subgroup of patients may have a primary immune attack directly against nerve axons, with sparing of myelin. The clinical presentation in these patients is similar to that of the principal type.
Subtypes of Guillain-Barré syndrome:
Several variants of GBS are recognized. These disorders share similar patterns of evolution, symptom overlap, and probable immune-mediated pathogenesis. Recovery from them varies.

Acute inflammatory demyelinating polyneuropathy
The acute inflammatory demyelinating polyneuropathy (AIDP) subtype is the most commonly identified form in the United States. It is generally preceded by a bacterial or viral infection. Nearly 40% of patients with AIDP are seropositive for C jejuni. Lymphocytic infiltration and macrophage-mediated peripheral nerve demyelination is present. Symptoms generally resolve with remyelination.

Acute motor axonal neuropathy
The acute motor axonal neuropathy (AMAN) subtype is a purely motor disorder that is more prevalent in pediatric age groups.] AMAN is generally characterized by rapidly progressive symmetrical weakness and ensuing respiratory failure.
Nearly 70-75% of patients with AMAN are seropositive for Campylobacter, with the majority of cases of AMAN being associated with preceding C jejuni diarrhea. Patients typically have high titers of antibodies to gangliosides (ie, GM1, GD1a, GD1b). Inflammation of the spinal anterior roots may lead to disruption of the blood-CNS barrier. Biopsies show wallerianlike degeneration without significant lymphocytic inflammation.
Many cases have been reported in rural areas of China, especially in children and young adults during the summer months. Pure axonal cases may occur more frequently outside of Europe and North America. AMAN cases may also be different from cases of axonal GBS described in the West.
Prognosis is often quite favorable. Although recovery for many is rapid, severely disabled patients with AMAN may show improvement over a period of years.
One third of patients with AMAN may actually be hyperreflexic. Although the mechanism for this hyperreflexia is unclear, dysfunction of the inhibitory system via spinal interneurons may increase motor neuron excitability. Hyperreflexia is significantly associated with the presence of anti-GM1 antibodies. 

Acute motor-sensory axonal neuropathy
Acute motor-sensory axonal neuropathy (AMSAN) is a severe acute illness differing from AMAN in that it also affects sensory nerves and roots. [17] Patients are typically adults. AMSAN often presents as rapid and severe motor and sensory dysfunction. Marked muscle wasting is characteristic, and recovery is poorer than it is from electrophysiologically similar cases of AMAN.
As with AMAN, AMSAN is often associated with preceding C jejuni diarrhea. Pathologic findings show severe axonal degeneration of motor and sensory nerve fibers with little demyelination.


Miller-Fisher syndrome
Miller-Fisher syndrome (MFS), which is observed in about 5% of all cases of GBS, classically presents as a triad of ataxia, areflexia, and ophthalmoplegia. Acute onset of external ophthalmoplegia is a cardinal feature. Ataxia tends to be out of proportion to the degree of sensory loss. Patients may also have mild limb weakness, ptosis, facial palsy, or bulbar palsy. Patients have reduced or absent sensory nerve action potentials and absent tibial H reflex.
Anti-GQ1b antibodies are prominent in MFS, and have a relatively high specificity and sensitivity for the disease.Dense concentrations of GQ1b ganglioside are found in the oculomotor, trochlear, and abducens nerves, which may explain the relationship between anti-GQ1b antibodies and ophthalmoplegia. Patients with acute oropharyngeal palsy carry anti-GQ1b/GT1a IgG antibodies.Recovery generally occurs within 1-3 months.

Acute panautonomic neuropathy
Acute panautonomic neuropathy, the rarest GBS variant, involves the sympathetic and parasympathetic nervous systems. Patients have severe postural hypotension, bowel and bladder retention, anhidrosis, decreased salivation and lacrimation, and pupillary abnormalities. Cardiovascular involvement is common, and dysrhythmias are a significant source of mortality. Significant motor or sensory involvement is lacking. Recovery is gradual and often incomplete.

Pure sensory GBS
A pure sensory variant of GBS has been described in the literature. It is typified by a rapid onset of sensory loss, sensory ataxia, and areflexia in a symmetrical and widespread pattern. Lumbar puncture studies show albuminocytologic dissociation in the CSF, and results from electromyography (EMG) show characteristic signs of a demyelinating process in the peripheral nerves.
The prognosis in pure GBS is generally good. Immunotherapies, such as plasma exchange and the administration of IVIGs, can be tried in patients with severe disease or slow recovery.

Other variants
The pharyngeal-cervical-brachial variant of GBS is distinguished by isolated facial, oropharyngeal, cervical, and upper limb weakness without lower limb involvement. There can be combinations of any of the above subtypes, and virtually any combination of nerve injury. There are likely mild cases that cause temporary symptoms, improve spontaneously, and never get definitively diagnosed.
Other unusual clinical variants with restricted patterns of weakness are observed only in rare cases.





Etiology:
GBS is considered to be a postinfectious, immune-mediated disease targeting peripheral nerves. Up to two thirds of patients report an antecedent bacterial or viral illness prior to the onset of neurologic symptoms.Respiratory infections are most frequently reported, followed by gastrointestinal infections. Administration of certain vaccinations and other systemic illnesses have also been associated with GBS. Case reports exist regarding numerous medications and procedures; however, whether any causal link exists is unclear.
C jejuni:
In several studies, C jejuni was the most commonly isolated pathogen in GBS. Serology studies in a Dutch GBS trial identified 32% of patients as having had a recent C jejuni infection, while studies in northern China documented infection rates as high as 60%. 
Gastrointestinal and upper respiratory tract symptoms can be observed with C jejuni infections. C jejuni infections can also have a subclinical course, resulting in patients with no reported infectious symptoms prior to the development of GBS. Patients who develop GBS following an antecedent C jejuni infection often have a more severe course, with rapid progression and a prolonged, incomplete recovery. A strong clinical association has been noted between C jejuni infections and the pure motor and axonal forms of GBS.
The virulence of C jejuni is thought to result from the presence of specific antigens in its capsule that are shared with nerves. Immune responses directed against capsular lipopolysaccharides produce antibodies that cross-react with myelin to cause demyelination. C jejuni infections also generate anti-ganglioside antibodies—including to the gangliosides GM1, GD1a, GalNac-GD1a, and GD1b—that are commonly found in patients with AMAN and AMSAN, the axonal subtypes of GBS. (Patients with C. jejuni enteritis not complicated by GBS, however, do not produce the specific anti-ganglioside antibodies.)
Even in the subgroup of patients with GM1 antibodies, however, the clinical manifestations vary. Host susceptibility is probably one determinant in the development of GBS after infectious illness. 
Although GM1 antibodies can also be found in patients with demyelinating GBS, they are much less common in these cases. C. jejuni infection can also generate antibodies to the ganglioside GQ1b, a component of oculomotor nerve myelin; these are associated with MFS.
COVID-19:
Evidence exists that coronavirus disease 2019 (COVID-19) is linked to the development of neurologic complications, including GBS. By April 20, 2020, one case of GBS in a patient with COVID-19 had been reported out of China and five such cases had been reported out of Italy. A report on the Italian cases said that GBS developed 5-10 days after COVID-19 had been diagnosed, with three of the patients having the demyelinating form of GBS, and the other two appearing to have an axonal variant. 
In June 2020, the first US case report of a patient with GBS associated with COVID-19 was published. The syndrome developed soon after the individual became infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, with test results indicating that he had the demyelinating form of GBS.
Epidemiology:
GBS is a rare disease with an incidence of 0.81–1.89 (median 1.11) per 100,000 person–years, and is more common in men than in women (ratio 3:2).1,16 Worldwide, the incidence is variable; for example, a low rate of 0.40 per 100,000 person–years was reported in Brazil, in contrast to a high rate of 2.5 per 100,000 person–years in Curaçao and Bangladesh.16–20 GBS seems to occur less frequently in children (0.34–1.34 per 100,000 person-years) than in adults, 18 and its incidence increases with age 16.18.
Figure 1 | The course of GBS. The majority of patients with GBS report an infection before the onset of weakness. Antiganglioside antibodies are often detected; their levels decrease over time. Different types of antibodies are related to the preceding infection and the GBS subtype. Progressive weakness reaches its maximum within 4 weeks (often within 2 weeks). The recovery phase may last many weeks, months or even years. Abbreviation: GBS, Guillain–Barré syndrome. Reprinted from Lancet Neurology 7, van Doorn, P. A., Ruts, L. & Jacobs, B. C. Clinical features, pathogenesis, and treatment of Guillain–Barré syndrome, 939–950 © (2008), with permission from Elsevier.

The background incidence of GBS in most studies remains constant over time, although seasonal fluctuations have occasionally been found in studies from Curaçao, Bangladesh and China. The proportions of patients with GBS who have AIDP and AMAN vary greatly around the world. AIDP is the predominant subtype (60–80% of patients) in North America and Europe. By contrast, the frequency of AMAN ranges from 6–7% in the UK and Spain to 30–65% in Asia, Central America and South America. The geographical diversity is probably attributable to differences in exposure to certain types of infection, possibly in combination with different genetic susceptibilities due to varying genetic polymorphisms between individuals or groups of people living in different areas of the world. These differences may be related not only to the development of a specific GBS subtype, but also to the course and severity of disease. Genetic studies with a high number of patients are required to investigate these relationships.

The background incidence of GBS in most studies remains constant over time, although seasonal fluctuations have occasionally been found in studies from Curaçao, Bangladesh and China. The proportions of patients with GBS who have AIDP and AMAN vary greatly around the world. AIDP is the predominant subtype (60–80% of patients) in North America and Europe. By contrast, the frequency of AMAN ranges from 6–7% in the UK and Spain to 30–65% in Asia, Central America and South America. The geographical diversity is probably attributable to differences in exposure to certain types of infection, possibly in combination with different genetic susceptibilities due to varying genetic polymorphisms between individuals or groups of people living in different areas of the world. These differences may be related not only to the development of a specific GBS subtype, but also to the course and severity of disease. Genetic studies with a high number of patients are required to investigate these relationships.

Pathogenesis:
As indicated above, GBS is a postinfectious disorder. Two-thirds of patients report symptoms of a respiratory or gastrointestinal tract infection before the onset of GBS. In about half of patients with GBS, a specific type of preceding infection can be identified, and C. jejuni is responsible for at least one-third of these infections. Other pathogens that cause antecedent infections related to GBS are cytomegalovirus, Epstein– Barr virus, Mycoplasma pneumonia, Haemophilus influenzae, and influenza A virus. Notably, a case–control study conducted in the Netherlands showed that 5% of patients with GBS had a hepatitis E virus infection before onset of GBS, compared with 0.5% of matched healthy controls. Similarly, 10% of patients with GBS from Bangladesh had an antecedent hepatitis E virus infection, indicating that hepatitis E virus is a worldwide trigger of GBS.30 However, despite the strong association between specific acute infections and GBS, the overall risk of developing this severe postinfectious complication is very small. Only one in 1,000–5,000 patients with Campylobacter enteritis will develop GBS in the subsequent 2 months.This fact explains why GBS is a sporadic disorder, although outbreaks of GBS after C. jejuni infection have occasionally been reported. One of the critical steps in GBS pathogenesis after C. jejuni infection is the generation of antibodies that crossreact with specific gangliosides (Figure 2), which are not produced during uncomplicated C. jejuni gastroenteritis. However, the production of crossreactive antibodies is only induced in susceptible individuals. Antibodies that crossreact with various gangliosides have been described in patients with GBS. However, only a subset of C. jejuni strains contain lipo-oligosaccharides that mimic the carbohydrate moiety of gangliosides that are present in human peripheral nerves (Figure 2). The synthesis of these ganglioside-mimicking carbohydrate structures depends on a set of polymorphic genes and enzymes that vary greatly between different C. jejuni strains. The Thr51 variant of the C. jejunicstII gene is associated with the occurrence of GBS, while the Asn51 variant is associated with MFS. Some antibody specificities are associated with particular GBS subtypes and related neurological deficits, reflecting the distribution of different gangliosides in human peripheral nerves (Table 1). C. jejuni infections are predominantly, but not exclusively, related to the AMAN or pure motor subtype of GBS. Patients with AMAN frequently have serum antibodies against GM1a, GM1b, GD1a and GalNAc-GD1a gangliosides. Patients with MFS or MFS–GBS overlap syndrome (see below) frequently have antibodies against GD1b, GD3, GT1a and GQ1b gangliosides, which are related to ataxia and ophthalmoplegia. In a study from the Netherlands, 20% of patients with AIDP related to cytomegalovirus infection had anti-GM2 antibodies, although these antibodies are also found in patients with uncomplicated cytomegalovirus infections. Interestingly, as well as antibodies against single ganglio sides, patients can also have antibodies against combinations of epitopes from ganglioside complexes. Such complexes are located in specialized microdomains, or ‘lipid rafts’, in the cell membrane. Antibodies that target ganglioside complexes also crossreact with C. jejuni lipo-oligosaccharides, and are probably induced by a preceding infection with C. jejuni. Antibodies against various combinations or complexes of glycolipids have also been reported in patients with AIDP, although the role of these antibodies in its pathogenesis remains to be determined.  
Figure 2 | Immunopathogenesis of GBS: molecular mimicry and antiganglioside antibodies. Infections with pathogens, such as Campylobacter jejuni, can trigger humoral immune and autoimmune responses that result in nerve dysfunction and the symptoms of GBS. Lipo-oligosaccharides on the C. jejuni outer membrane may elicit the production of antibodies that crossreact with gangliosides, such as GM1 and GD1a on peripheral nerves. The antigens targeted in AMAN are located at or near the node of Ranvier. The anti-GM1 and anti-GD1a antibodies bind to the nodal axolemma, leading to complement activation followed by MAC formation and disappearance of voltage-gated sodium channels. This damage can lead to detachment of paranodal myelin, and nerve conduction failure. Macrophages then invade from the nodes into the periaxonal space, scavenging the injured axons. The antigens targeted in AIDP are, presumably, located on the myelin sheath. The antibodies can activate complement, which leads to formation of the MAC on the outer surface of Schwann cells, initiation of vesicular degeneration, and invasion of myelin by macrophages. Abbreviations: AIDP, acute inflammatory demyelinating polyneuropathy; AMAN, acute motor axonal neuropathy; APC, antigen-presenting cell; GBS, Guillain–Barré syndrome; MAC, membrane attack complex.

In conjunction with the presence of antiganglioside antibodies, complement activation seems to contribute to nerve degeneration in GBS—a phenomenon that has been studied at the nodes of Ranvier and at the motor nerve terminal in a mouse model of AMAN. Sodium channel clusters, as well as paranodal axoglial junctions, the nodal cytoskeleton, and Schwann cell microvilli, all of which stabilize the sodium channel clusters, were disrupted by complement activation in a GBS disease model. Additional studies in a GBS mouse model provided evidence that blockade of complement activation prevents emergence of the clinical signs of antiganglioside-mediated neuropathy.61 The development of GBS after a C. jejuni infection may also depend on patient-related factors that influence the susceptibility to produce crossreactive, carbohydratetargeted antibodies. This hypothesis is supported by the fact that GBS has a relapse rate of 5%, which is clearly higher than would be expected by chance. The initial pathogen–host interaction has a key role in the development of GBS. C. jejuni lipo-oligosaccharides bind to siglec-7 (sialic acid-binding immunoglobulin-like lectin 7) and activate dendritic cells via Toll-like receptor 4 and CD14. These dendritic cells produce type 1 interferon and tumour necrosis factor (TNF), which induce proliferation of B cells. This immune activation could be influenced by genetic polymorphisms but, to date, genetic factors have only been studied in small cohorts of patients. Interestingly, a meta-analysis identified a moderate association between GBS and a particular TNF polymorphism. In addition, an association between polymorphisms in the MBL2 gene (encoding mannose-binding protein C) and the severity and outcome of GBS has been confirmed. Future genome wide association studies in large, well-described and adequately controlled cohorts are required to establish the role of host factors in the pathogenesis of GBS.

The potential role of vaccination:
A few patients develop GBS shortly after receiving a vaccination. Despite their rarity, such events cause con siderable public concern. In the vaccination campaign against influenza A (H1N1) in the USA in 1976, the estimated attributable risk of vaccine-related GBS was about one in 100,000.66 A similar association was suggested for the vaccination campaign against influenza A (H1N1) in 2009, but extensive national and international studies found that vaccination was associated with only a small attributable risk of GBS: 1.6 excess cases of GBS per 1,000,000 vaccine recipients, a frequency similar to that for all seasonal vaccinations. In fact, vaccination might even reduce the risk of acquiring GBS, as this condition can be caused by infections such as influenza. The risk of developing GBS after influenza infection is estimated to be 4–7 times higher than after influenza vaccination. No relapses of GBS in patients with a history of this disease have been observed after influenza vaccination. For these reasons, the following practical guideline regarding vaccination of patients with a history of GBS is currently used in the Netherlands: GBS as such is not an indication for influenza vaccination, and vaccination seems to be safe in patients who developed GBS >3 months ago and when onset of GBS was not shortly after vaccination.

Diagnosis:
Diagnostic criteria:
In 1978, the US National Institute of Neurological Disorders and Stroke (NINDS) developed case definitions for GBS in the course of investigating the suspected association between GBS and the swine flu vaccination campaign of 1976–1977. The initial diagnostic criteria published in 1981 were modified in 1990. Though primarily developed for research purposes, they are probably still the most widely used criteria in clinical practice.4 The criteria consist of features that are required for or strongly support the diagnosis of GBS, and features that cast doubt on the diagnosis (Box 1). In 2011, the Brighton Collaboration published new case definitions for GBS while studying a possible association between GBS and the H1N1 swine flu vaccination campaign of 2009–2010. These criteria were specifically developed for retrospective epidemiological and vaccine safety studies and, consequently, are likely to combine high specificity with limited sensitivity. The Brighton criteria identify GBS with four levels of diagnostic certainty, from level 1 (highest) to level 4 (lowest). Use of the Brighton criteria to classify patients with suspected GBS is highly dependent on completeness of the diagnostic data. A study from the Netherlands in 335 patients with GBS with complete sets of diagnostic data—which are required for level 1 certainty according to the Brighton criteria—classified 61% as level 1, 33% as level 2, none as level 3 and 6% as level 4. However, patients diagnosed at different levels of diagnostic certainty did not differ in disease severity or outcome. In studies from Korea and India in patients who had GBS, 24% and 14% of patients, respectively, were classified as level 4. The Brighton criteria are not, however, intended to be used for diagnostic purposes in clinical practice. Further research is needed to develop criteria that can be used to diagnose GBS and its less-frequent variants in the acute phase of the disease. However, in practice, the criteria published in 1990 still provide a good basis for clinicians worldwide to make a diagnosis of GBS.

Treatment:
Treatment of GBS usually combines multidisciplinary supportive medical care and immunotherapy. Proven effective treatments for GBS are IVIg and plasma exchange. Immunotherapy is usually started if patients are not able to walk 10 m unaided (GBS Disability Scale score ≥3). Plasma exchange and IVIg have pleiotropic immunomodulatory effects, but we have yet to establish which effects explain their therapeutic efficacy in GBS, and whether the same effects are involved in all patients and all subtypes of GBS. IVIg treatment may inhibit Fc-mediated activation of immune cells, binding of antiganglioside antibodies to their neural targets or local complement activation. Serum IgG Fc glycosylation in patients with GBS seems to be associated with disease severity and could influence the immunomodulatory effects of IVIg. Plasma exchange is thought to remove neurotoxic antibodies, complement factors and other humoral mediators of inflammation. Plasma exchange is beneficial when performed within the first 4 weeks after onset of weakness in patients who are unable to walk unaided (GBS Disability Scale score ≥3), but the largest effect is seen when treatment is started within the first 2 weeks. The usual plasma exchange regimen consists of five treatments administered over 2 weeks, involving a total of about five plasma volumes. In mildly affected patients (still able to walk), however, two plasma exchange sessions induced more-rapid onset of motor recovery than did no plasma exchange. IVIg is effective in patients who are unable to walk 10 m unaided (GBS Disability Scale score ≥3) and when started within 2 weeks of onset of weakness. Randomized controlled trials showed that IVIg at a dose of 0.4 g/kg daily for 5 consecutive days (or 1 g/kg daily for 2 days) was as effective as a full course of five plasma exchange sessions applied over 2 weeks. Whether rapid IVIg treatment over 2 days is superior to treatment with the same total dose (2 g/kg) administered over 5 days has not been fully evaluated. However, one trial demonstrated that children receiving treatment over 2 days more frequently had treatment-related fluctuations than did children receiving treatment over 5 days. As IVIg therapy is widely available, does not require special equipment, and generally has only minor adverse effects, it has replaced plasma exchange as the preferred treatment for GBS in many hospitals. Immunoabsorption, as an alternative to plasma exchange, is occasionally used as a treatment for patients with GBS, and may be equally effective. However, no large-scale randomized controlled trials have shown that treatments other than IVIg or plasma exchange are effective. The choice of treatment depends on both patientrelated and socioeconomic factors. For instance, plasma exchange requires special equipment and is not always available in all hospitals. In addition, plasma exchange can be difficult to perform in young children, and care should be taken in patients with autonomic cardiovascular instability because of the large volume shifts involved in the plasma exchange procedure. However, the direct costs of IVIg treatment can be more than twice those of plasma exchange, making this treatment less attractive in low-income countries. In this respect, it is important to remember that most clinical trials of these treatments were conducted in Western Europe or North America and, therefore, predominantly involved patients who fulfilled the most commonly used GBS diagnostic criteria.4 The results of these trials might be less applicable in other parts of the world, especially where AMAN is highly prevalent. Whether patients with AMAN should receive the same treatment as those with AIDP remains uncertain. Results from a small study, which unfortunately had some methodological flaws, suggested that patients with AMAN might have better outcomes after treatment with plasma exchange than after IVIg therapy, and that plasma exchange was also the most cost-effective option. However, in countries where plasma exchange machines are not widely available or patients cannot afford this expensive procedure, small-volume plasma exchange or exchange transfusion can be a low-cost therapeutic option. Controlled studies of these procedures are currently lacking. The combination of plasma exchange followed by IVIg is not significantly better than either plasma exchange or IVIg alone. Oral steroids and intravenous methylprednisolone are not beneficial in patients with GBS. The combination of IVIg and methylprednisolone is no more effective than IVIg alone, although this combined treatment might have some additional short-term benefits when known prognostic factors are taken into account. Small randomized placebo-controlled trials of IFN-β1a and brain-derived neurotrophic factor, and one trial studying a 6 week course of mycophenolate mofetil combined with standard IVIg versus IVIg alone, did not indicate beneficial effects of these treatments. No randomized controlled trials have been performed in patients with MFS.126 A retrospective analysis showed that recovery starts slightly earlier in patients with MFS treated with IVIg than in those who were treated with plasma exchange or received no immunotherapy. However, final outcomes were the same in all three groups. Indeed, almost all patients with MFS recover fully, irrespective of whether they receive immunotherapy. Owing to the lack of evidence of a beneficial effect of IVIg or plasma exchange in patients with MFS, combined with the good natural recovery seen in these patients, withholding of immunotherapy in patients with MFS seems currently justified. However, patients with MFS–GBS overlap syndrome can be severely affected, and treatment with IVIg or plasma exchange remains an option for these patients. Notably, no large-scale randomized controlled trials have been performed to determine the optimal treatment strategy in children with GBS and they are, therefore, usually treated in the same manner as adults with GBS.



Ongoing research:
Nearly a century after it was first described, GBS is still a life-threatening disorder that results in a poor outcome in at least 20% of patients and has persistent residual effects in the majority. Further research is urgently required to improve this situation. From a clinical perspective, the following are the most challenging needs: to develop improved diagnostic criteria for use in daily clinical practice, trials and vaccine safety studies; to determine the burden of disease caused by GBS worldwide; to develop new and better GBS outcome measures; to establish the precipitating events and patient-related factors that lead to GBS; to define biological and clinical predictors of the clinical course and outcome in individual patients; and, most importantly, to develop moreeffective and specific treatments, as well as protocols for supportive care. These aims can probably only be achieved by largescale international and multidisciplinary collaborations, such as the International GBS Outcome Study (IGOS), which was launched in 2012. Tissue samples and detailed, standardized clinical data are being collected during a follow-up period of 1–3 years with the intention of including at least 1,000 patients with GBS from all over the world. At present, centres from 17 countries— Argentina, Australia, Bangladesh, Belgium, Canada, Denmark, France, Germany, Italy, Japan, Malaysia, Netherlands, Spain, South Africa, Taiwan, UK and the USA—are recruiting patients. In addition, a randomized controlled trial, the SID-GBS study, is being conducted in the Netherlands. This trial is investigating the effect of a second course of IVIg given shortly after the first course in patients with GBS who have a poor prognosis (defined as a mEGOS score of 6–12 at 1 week after initiation of a standard 5 day course of IVIg). A related international study with an observational prospective design (I-SID-GBS) is investigating the same approach. This study is part of IGOS and is being performed by the Inflammatory Neuropathy Consortium. In addition, a new randomized placebo-controlled trial of eculizumab in patients with early GBS who are unable to walk is about to start. This study is partly based on findings in an animal model of GBS, in which antiganglioside antibodies induce complementdependent damage at the nodes of Ranvier, nerve terminals, and perisynaptic Schwann cells (Figure 2). Notably, these deleterious effects of complement on nerve terminals in mice can be blocked by the administration of eculizumab, a humanized monoclonal antibody that binds with high affinity to complement factor C5 and prevents its cleavage to C5a and the proinflammatory, cytolytic C5b-9 complex.61 Many other studies, such as those investigating pain treatment, nerve regeneration, and other factors that may improve the outcomes of patients with GBS, are eagerly awaited.

Litrature Review:
The understanding of the disease mechanism of Guillain–Barré syndrome has evolved in recent years. Development of new treatments has been limited since immunotherapy was introduced in the 1980s and 1990s. An animal model (experimental autoimmune neuritis in rats) is often used for studies, and some agents have shown promise: glatiramer acetate, quinupramine, fasudil (an inhibitor of the Rhokinase enzyme) and the heart drug flecainide. An antibody targeted against the anti-GD3 antiganglioside antibody has shown benefit in laboratory research. Given the role of the complement system in GBS, it has been suggested that complement inhibitors (such as the drug eculizumab) may be effective 

Sara Morsy et.al (2020) : The study suggests that NCAM may play a significant role in the immunopathogenesis of GBS. NCAM antibodies can be used as a marker for Guillain-Barré syndrome. However, more experimental studies are needed to prove these results. This study aimed at identifying human neural proteins that can be attacked by cross-reacting SARS-COV-2 antibodies causing Guillain-Barré syndrome. These markers can be used for the diagnosis of Guillain-Barré syndrome (GBS). To achieve this goal, proteins implicated in the development of GBS were retrieved from literature. These human proteins were compared to SARS-COV-2 surface proteins to identify homologous sequences using Blastp. Then, MHC-I and MHC-II epitopes were determined in the homologous sequences and used for further analysis. Similar human and SARS-COV-2 epitopes were docked to the corresponding MHC molecule to compare the binding pattern of human and SARS-COV-2 proteins to the MHC molecule. 
Badshah et al (2019) : The Zika virus (ZIKV) has gained attention for the last few years due to the congenital microcephaly and Guillain–Barre Syndrome that resulted in humans. The non-structural protein (NS3) helicase of ZIKV play an important role in viral RNA replication. In this article, the researchers performed hundred nanosecond molecular dynamics simulation and molecular docking of the NS3 helicase of ZIKV with 1,4-benzothiazine derivatives. 
Pier Paolo Sainaghi et al (2010) : Patients and methods: CSF samples were collected during a diagnostic lumbar puncture and stored at 30 C.Weanalyzed the CSF of nine subjects with GBS; eight with CIDP; eight with diabetic polyneuropathy (DP) and seven with headache (controls). Fifty inflammatory mediators were simultaneously measured with a multiplex bead-based ELISA on a Suspension Array System. After Bonferroni’s correction for repeated measures, non-parametric variance and post hoc test were calculated. Results: Thirty-two inflammatory mediators were expressed. The median concentration of IL-6, IL-9, IL15, IL-18, CCL4, CXCL1, LIF, MIF, PDGFbb, IFN-c2, IL-2ra, IL-12(p40), IL-16, SCGF-b, TRAIL, FGF, G-CSF, GMCSF, and M-CSF was not different among groups (variance: n.s.). The median concentration of CCL2, CCL7, CCL27, CXCL9, CXCL10, CXCL12, ICAM1, VCAM1 and VEGF was higher in CIDP and GBS compared with controls (p < 0.002). The median concentration of IL-8 and IL-1ra was higher in GBS than CIDP or DP or controls, whereas stem cell factor (SCF) and hepatocyte growth factor (HGF) were higher in CIDP than GBS or DP or controls (p < 0.002). 
Michiaki Koga et al (2023) Objective : To investigate the frequency of serum autoantibodies targeting contactin-associated protein 1 (Caspr1) and its complexes with other paranode antigens, contactin-1 (CNTN1) and neurofascin 155 (NF155), in Japanese patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). 
Results :Anti-Caspr1 antibodies were present in one participant (case 1, 3.8%) of CIDP, and negative in all Guillain–Barré syndrome patients and healthy participant. The detected anti-Caspr1 antibodies predominantly belonged to the immunoglobulin G4 subclass, and the addition of CNTN1 to Caspr1 as an antigen increased antibody reactivity, although the increase was just 20–30% at most. The presence of autoantibodies against paranode protein complexes, including Caspr1/CNTN1, Caspr1/NF155 and Caspr1/CNTN1/NF155, was confirmed in several CIDP patients, although they also had anti-Caspr1 or anti-NF155 antibodies; thus, in our cohort, there were no patients with autoantibodies that specifically recognized paranode protein complexes. 

J´ er ˆome J. Devaux , Masaaki Odaka , and Nobuhiro Yuki (2012) Neurofascin-186 (NF186), neuronal cell adhesion molecule (NrCAM), and gliomedin are adhesion molecules playing a central role in the formation of nodes of Ranvier. In Guillain-Barr´ e syndrome (GBS), immune attack toward the nodes may participate in the disabilities. Autoantibodies to NF186 and gliomedin have been detected in a rat model of GBS. Here, researcher investigated the prevalence of antibodies against nodal adhesion molecules in patients with GBS or chronic inflammatory demyelinating polyneuropathy (CIDP). 
Mingyun Shen et al (2013) : Rho kinases (ROCK1 and ROCK2) belong to serine/threonine (Ser/Thr) protein kinase family, and play the central roles in the organization of the actin cytoskeleton. Therefore, Rho kinases have become attractive targets for the treatments of many diseases, such as cancer, renal disease, hypertension, ischemia, and stroke. In order to develop small-molecule inhibitors of ROCK1, molecular docking was utilized to virtually screen two chemical databases and identify molecules that interact with ROCK1. 
Marc’s Jacobs et.al (2005): The ROCK protein consists of several domains: an N-terminal region, a kinase catalytic domain, a coiled-coil domain containing a RhoA binding site, and a pleckstrin homology domain. The Cterminal region of ROCK binds to and inhibits the kinase catalytic domains, and this inhibition is reversed by binding RhoA, a small GTPase. This report present the structure of the N-terminal region and the kinase domain. In given protein two N-terminal regions interact to form a dimerization domain linking two kinase domains together. This spatial arrangement presents the kinase active sites and regulatory sequences on a common face affording the possibility of both kinases simultaneously interacting with a dimeric inhibitory domain or with a dimeric substrate. The kinase domain adopts a catalytically competent conformation; however, no phosphorylation of active site residues is observed in the structure. They also determined the structures of ROCK bound to four different ATP competitive small molecule inhibitors (Y-27632, fasudil , hydroxyfasudil, and H-1152P)

Molecular Docking:
Molecular Docking is performed in four important steps –
1)	Protein preparation
2)	Ligand preparation
3)	Receptor grid generation
4)	Molecular docking (Ligand docking)

Protein Preparation: 
Preparing a protein for molecular docking, especially for rho kinase (ROCK), involves a meticulous series of steps aimed at ensuring its structural integrity and suitability for computational analysis. Firstly, the crystal structure of rho kinase is retrieved from a reliable protein structure database like the Protein Data Bank (PDB), ensuring high resolution and relevant ligands or co-factors if needed. Subsequently, the protein structure undergoes thorough preparation, which includes removing water molecules, heteroatoms, and any extraneous entities not pertinent to the docking study. Any structural irregularities or missing residues are corrected, and any hydrogen atoms missing from the structure are added. Energy minimization is then performed to alleviate steric clashes and optimize the protein's conformation for docking, utilizing molecular
 modeling software such as GROMACS, CHARMM, or Schrödinger suite, along with an appropriate force field. Ligands intended for docking undergo a similar preparation process, including removal of water molecules and energy minimization to attain stable conformations. The next step involves defining a docking grid around the active site of rho kinase, crucial for guiding the docking software in predicting accurate ligand binding poses. Molecular docking is then executed using specialized software such as AutoDock, AutoDock Vina, or GOLD, docking the prepared ligands into the active site and assessing the binding affinities of resultant complexes. Following docking, thorough analysis and visualization of results are conducted to identify potential ligand-protein interactions and select promising ligand poses, facilitated by molecular visualization tools like PyMOL or VMD. Validation of docking results through experimental assays, such as enzyme inhibition assays or biochemical assays, is imperative to confirm predicted binding interactions. Further optimization may be pursued based on docking results and experimental validation, including refining ligands or conducting additional rounds of docking with modified ligands to enhance binding affinities and selectivity. Finally, meticulous documentation of all steps undertaken during protein preparation and docking is essential for reproducibility and dissemination of findings to the scientific community through publications or presentations. 

Fig: Rho Kinase

Ligand Preparation:
In the realm of molecular docking studies, the preparation of ligands stands as a pivotal phase, ensuring their readiness for accurate binding within the protein's active site. A comprehensive approach to ligand preparation entails several systematic steps. Initially, the 2D or 3D structure of the ligand of interest is acquired from reputable chemical databases like PubChem, ChEMBL, or ZINC, with utmost attention to ensuring compatibility with molecular modeling software. Following this, the ligand structure undergoes rigorous standardization, where potential errors such as missing atoms or bonds, incorrect valence, or inconsistent bond orders are meticulously addressed using sophisticated chemical structure editing tools such as Open Babel or RDKit. Subsequently, the determination of the ligand's protonation state at physiological pH, often around pH 7.4, is crucial. This task is accomplished using tools like MarvinSketch, Epik (Schrödinger suite), or online platforms like PROPKA. Energy minimization then ensues, aiming to optimize the ligand's geometry and eliminate steric clashes through the employment of molecular modeling software such as RDKit, Avogadro, or Schrödinger suite. The exploration of potential bioactive conformations involves the generation of tautomers and stereoisomers of the ligand, facilitated by advanced software tools like OpenEye Omega or Schrödinger's LigPrep. Additionally, the ligand's flexibility and binding modes are further scrutinized through the generation of multiple conformations using techniques such as molecular dynamics simulations or conformational sampling algorithms available in software tools like RDKit or OMEGA. The consideration of solvation effects is pivotal in accurate docking calculations, prompting the removal of explicit water molecules from the ligand's structure. Subsequent to the preparation steps, the ligand structure undergoes conversion into formats compatible with molecular docking software such as PDBQT, MOL2, or SDF. Validation of the prepared ligands is then conducted by comparing them with known bioactive conformations or experimental data, where available, to ensure reliability. Finally, meticulous documentation of all ligand preparation steps, inclusive of software tools used and parameters applied, is imperative for fostering reproducibility and facilitating the dissemination of findings within the scientific community. By adhering to this comprehensive approach, ligands are meticulously primed for molecular docking studies, thereby augmenting the accuracy and reliability of ensuing docking results.

Ligand Used:
Kaempferol 
IUPAC Name: 3,4′,5,7-Tetrahydroxyflavone 

Chemical Formula	C15H10O6
Molar Mass	286.23 g/mol
Density	1.688 g/mol
Melting Point	276-278 ℃

Natural Occurrence: 
Kaempferol is a secondary metabolite found in many plants, plant-derived foods, and traditional medicines. Its flavor is considered bitter. 
In Plants and Food: 
Kaempferol is common in  Pteridophyta, Pinophyta, and  Angiospermae. Within Pteridophyta and Pinophyta, kaempferol has been found in diverse families. Kaempferol has also been identified in Dicotyledons and Monocotyledons of Angiosperms. The total average intake of flavonols and flavones in a normal diet is estimated as 23 mg/day, to which kaempferol contributes approximately 17%. Common foods that contain kaempferol include: apples, grapes, tomatoes, green tea, potatoes, onions, broccoli, Brussels sprouts, squash, cucumbers, lettuce, green beans, peaches, blackberries, raspberries, and spinach. Plants that are known to contain kaempferol include Aloe vera, Coccinia grandis,  Cuscuta chinensis, Euphorbia pekinensis, Glycine max, Hypericum perforatum, Pinus sylvestris, Moringa oleifera, Rosmarinus officinalis, Sambucus nigra, Toona sinensis, and llexd . It also is present in endive. 


Quercetin  
IUPAC Name: 3,3′,4′,5,7-Pentahydroxyflavone 
Chemical Formula	C15H10O7
Molar Mass	302.236 g/mol
Appearance	yellow crystalline powder
Density	1.799 g/cm3
Melting Point	316 °C (601 °F; 589 K)
Solubility in water	Practically insoluble in water; soluble in aqueous alkaline solutions

Natural Occurrence: 
Quercetin is a flavonoid widely distributed in nature. The name has been used since 1857, and is derived from quercetum (oak forest), after the oak genus Quercus. It is a naturally occurring polar auxin transport inhibitor. 
Quercetin is one of the most abundant dietary flavonoids, with an average daily consumption of 25–50 mg. 
In red onions, higher concentrations of quercetin occur in the outermost rings and in the part closest to the root, the latter being the part of the plant with the highest concentration. One study found that organically grown tomatoes had 79% more quercetin than non-organically grown fruit. Quercetin is present in various kinds of honey from different plant sources.
Berberine
IUPAC Name: 9,10-Dimethoxy-7,8,13,13a-tetradehydro-2′H-[1,3]dioxolo[4′,5′:2,3]berbin-7-ium 

Chemical Formula	C20H18NO4+
Molar Mass	336.366 g.mol-1
Appearance	Yellow Solid
Melting Point	145 ℃ (293℉; 418 K)
Solubility in Water	Slowly soluble

Natural  Occurrence:
Berberine, a natural alkaloid compound, is widely distributed in plants across different genera, with notable concentrations found in species of the Berberis genus like Berberis vulgaris (barberry), Berberis aquifolium (Oregon grape), and Berberis aristata (Indian barberry). These plants, native to regions of Asia, Europe, and North America, serve as primary natural sources of berberine. Additionally, berberine can be found in smaller quantities in other plant families such as Ranunculaceae, Papaveraceae, and Menispermaceae. Beyond barberries, berberine is present in plants like Hydrastis canadensis (goldenseal), Coptis chinensis (Chinese goldthread), and Tinospora cordifolia (heart-leaved moonseed). Its extensive natural occurrence in various botanical species underscores its significance in traditional medicine systems, particularly in Ayurveda and Traditional Chinese Medicine. Berberine's diverse pharmacological properties, including antimicrobial, anti-inflammatory, and antioxidant effects, have spurred scientific interest in exploring its potential therapeutic applications for a range of health conditions.

Centaurein 
IUPAC Name: 5-hydroxy-2-(3-hydroxy-4-methoxyphenyl)-3,6-dimethoxy-7-[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2 yl]oxychromen-4-one
Chemical formula	C24H26O13
Molar mass	522.5 g/ml
Melting point	208-209 ͦ C
Density	1.6 ± 0.1 g/cm3
Solubility	Water soluble
Natural  Occurrence:
Centaurein, a flavonoid compound, is primarily found in plants belonging to the Centaurea genus, notably Centaurea cyanus (cornflower) and Centaurea montana (perennial cornflower or mountain bluet). These plants are indigenous to Europe and are characterized by their striking blue flowers. Additionally, centaurein can be present in other botanical species within the Asteraceae family, which encompasses a wide range of plants including sunflowers, daisies, and asters. While its concentration may vary, centaurein contributes to the biological activities of these plants and is often associated with their vibrant coloration and potential medicinal properties. Its natural occurrence in these diverse botanical sources underscores its ecological and pharmacological significance.

Pseudocoptisine
IUPAC Name: 5,7,18,20-tetraoxa-13-azoniahexacyclo[11.11.0.02,10.04,8.015,23.017,21]tetracosa-1(24),2,4(8),9,13,15,17(21),22-octaene

Chemical formula	C19H14NO4+
Molar mass	320.3 g/mol
Melting point	210-212 ℃
Solubility	Soluble in water

Natural  Occurrence: 
Pseudocoptisine, an alkaloid compound, naturally occurs in various plant species, predominantly within the genus Corydalis, which is part of the Papaveraceae family. Notably, Corydalis yanhusuo, indigenous to China, contains pseudocoptisine and has been utilized in traditional Chinese medicine for its potential health benefits. Beyond Corydalis yanhusuo, pseudocoptisine may also be found in other Corydalis species and related genera within the Papaveraceae family, albeit with variances in concentration. These plants serve as crucial natural reservoirs of pseudocoptisine, a compound of interest due to its pharmacological activities. Research into pseudocoptisine's therapeutic effects underscores its significance in herbal medicine and natural product drug discovery efforts.



Fasudil
IUPAC Name: 5-(1,4-diazepan-1-ylsulfonyl)isoquinoline

Chemical Formula 	C14H17N3O2S
Molar Mass 	291.37 g/mol
Melting Point 	208-215℃
Solubility	Soluble in Water
Density	1.25 g/cm3

Natural Occurrences:
Fasudil, a medication primarily prescribed for treating cerebral vasospasm resulting from conditions like subarachnoid hemorrhage, is not naturally occurring but synthesized in pharmaceutical laboratories. Its pharmacological mechanism involves inhibiting Rho kinase, an enzyme pivotal in smooth muscle contraction and cellular motility regulation. By impeding Rho kinase activity, fasudil facilitates vasodilation, which enhances blood flow and mitigates vasospasm. Although fasudil itself is not found in nature, the physiological pathways it influences are intrinsic to human biology.

Receptor grid generation:
Receptor grid generation stands as a pivotal stage in molecular docking studies, delineating the search space within the protein where ligands will engage in binding interactions. This critical process encompasses several meticulous steps to ensure the accuracy and reliability of subsequent docking calculations. Initially, the active site or binding pocket within the protein is meticulously identified, drawing upon experimental data from crystal structures of protein-ligand complexes or employing computational methods like binding site prediction algorithms. Subsequently, the dimensions of the grid box enclosing the active site are precisely defined, striking a balance between accommodating potential ligand binding orientations and maintaining computational efficiency. Determining the spacing between grid points within the grid box follows suit, ensuring adequate sampling of space for ligand binding without unduly prolonging computational time. Utilizing dedicated molecular docking software, such as AutoDockTools for AutoDock or Schrödinger's Glide for Glide, facilitates the generation of the receptor grid, incorporating tools specifically designed for this purpose. Centering the grid box coordinates around the active site ensures that ligands are docked within the pertinent region of the protein, optimizing docking accuracy. Visualizing the receptor grid using sophisticated visualization tools like PyMOL, VMD, or UCSF Chimera ensures its adequate coverage of the active site and the space where ligands are anticipated to bind. Validation of the generated receptor grid is imperative, necessitating comparison with experimental data or known binding poses of ligands to ascertain its fidelity in representing the binding site and facilitating accurate docking calculations. Comprehensive documentation of the parameters employed for receptor grid generation, encompassing grid dimensions, spacing, and center coordinates, underpins reproducibility and facilitates the dissemination of findings within the scientific community. By meticulously adhering to these steps, a receptor grid conducive to molecular docking studies is generated, enabling the precise prediction of ligand binding poses and affinities within the protein's active site.

Molecular docking (Ligand docking):
Ligand docking 
Docking protocol validation:
Validating a docking protocol for Rho kinase (ROCK) involves compiling a diverse ligand dataset, preparing the protein structure, and selecting appropriate docking software. The protocol is then set up with defined parameters and validated through docking simulations. Analysis includes comparing predicted poses with experimental structures and calculating docking scores against affinities. Optimization and cross-validation with independent datasets follow, ensuring consistency and robustness. Finally, the validated protocol is documented and published to contribute to ROCK-targeted drug discovery efforts.

Results:





Molecular Docking results:
The scoring functions used to assess docking of ligands with LasR used were docking score and glide score. Docking Score
•	The docking score and the GlideScore are the same with a minor difference 
•	The docking score is the sum of the GlideScore and the Epik "State Penalty". Used to assess docking of ligands.

Glide Score: 
•	GlideScore is an empirical scoring function that approximates the ligand binding free energy. Used to rank poses of different ligands.

Sr No.	Ligands	Docking Score	Glide Score
1	Fasudil	-9.026	-9.032
2	Quercatin	-8.039	-8.051
3	Kamphferol	-7.926	-7.938
4	Berbarine	-6.293	-6.293
5	Pseudocoptisine	-5.956	-5.956
6	Centaurein	-5.690	-5.690

Figure – Docking of Fasudil

Figure- Docking of Quercatin

Figure- Docking of Kamphferol

Figure- Docking of Berbarine

Figure- Docking of Pseudocoptisine

Figure- Docking of Centaurein

Discussion:

Fasudil:
Fasudil, characterized by a docking score of -9.026 and a Glide score of -9.032, emerges as a potent candidate in molecular docking studies. Widely recognized for its role as a Rho-kinase inhibitor, Fasudil holds significant therapeutic promise, particularly in the management of cerebral vasospasm and as a vasodilator. Its exceptionally high negative docking score underscores its strong binding affinity with the target protein, suggesting a robust potential for further exploration in drug development initiatives.

 Quercetin:
With a docking score of -8.039 and a Glide score of -8.051, Quercetin emerges as a notable contender in molecular docking analyses. As a flavonoid abundantly present in various fruits, vegetables, and grains, Quercetin has garnered attention for its antioxidant and anti-inflammatory properties. The docking score underscores its promising binding affinity with the target protein, accentuating its potential as a candidate for drug discovery and development efforts.

Kaempferol:
Kaempferol, with a docking score of -7.926 and a Glide score of -7.938, exhibits substantial promise in molecular docking investigations. Found in a multitude of plants such as tea, broccoli, and ginkgo biloba, Kaempferol is renowned for its antioxidant, anti-inflammatory, and anticancer activities. While its docking score indicates moderate binding affinity, Kaempferol warrants further exploration as a lead compound for optimization in drug discovery endeavors.

Berberine:
Berberine, characterized by a docking score of -6.293 and a Glide score of -6.293, presents intriguing possibilities in molecular docking assessments. This isoquinoline alkaloid, prevalent in plants like goldenseal and barberry, has been extensively studied for its antimicrobial, anti-inflammatory, and antidiabetic effects. While its docking score suggests relatively weaker binding affinity compared to other ligands, Berberine remains a subject of interest for potential therapeutic applications.

Pseudocoptisine:
Pseudocoptisine, with a docking score of -5.956 and a Glide score of -5.956, emerges as a candidate worthy of further investigation in molecular docking studies. As an alkaloid found in certain traditional Chinese medicinal herbs, Pseudocoptisine's pharmacological properties warrant deeper exploration. While its docking score indicates moderate binding affinity, additional research is necessary to validate its potential as a viable drug candidate.

Centaurein:
Centaurein, with a docking score of -5.690 and a Glide score of -5.690, presents insights into its binding affinity in molecular docking analyses. This flavonoid, found in various plants including Centaurea species, is currently under investigation for its biological activities and pharmacological properties. While its docking score suggests relatively weaker binding affinity compared to other ligands listed, Centaurein remains a subject of interest for potential therapeutic applications.