Publications by authors named "Ramkumar Subramanian"

Narcolepsy is a rare, chronic neurological disorder characterized by a dysregulated sleep-wake cycle, with core clinical features including excessive daytime sleepiness (EDS), cataplexy, hypnopompic/hypnagogic hallucinations, and sleep paralysis. Several treatment options are available for the symptomatic management of narcolepsy, but they have limitations. Comorbidities of narcolepsy further limit the treatment choices.

View Article and Find Full Text PDF

As the available treatments for moderate-to-severe atopic dermatitis (AD) expand, understanding patient and physician preferences becomes crucial for informed decision-making. To quantify patient and physician preferences for biologics and oral systemic AD treatment attributes. We conducted a cross-sectional, online discrete choice experiment (DCE) involving 306 AD patients and 206 physicians throughout the United Kingdom and Germany.

View Article and Find Full Text PDF

Alzheimer's disease (AD) is a progressive neurodegenerative disorder which affects cognitive functions with negative impact on day to day activities and an ultimate loss of independent living. Current standard of care (SOC) for AD, viz. donepezil, rivastigmine, galantamine, memantine etc.

View Article and Find Full Text PDF
Article Synopsis
  • - The study assessed the impact of masupirdine (SUVN-502) on neuropsychiatric symptoms in patients with moderate Alzheimer's Disease, revealing no significant difference between the drug and placebo in the primary outcomes.
  • - However, post hoc analyses showed that masupirdine at doses of 50 mg and 100 mg significantly reduced agitation/aggression and psychosis symptoms in specific subgroups compared to placebo, with effects sustained for up to 26 weeks in some cases.
  • - The researchers concluded that more studies are needed to further investigate the potential benefits of masupirdine on neuropsychiatric symptoms in Alzheimer's patients.
View Article and Find Full Text PDF

Introduction: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive deterioration in cognition, memory and activities of daily living. Selective blockade of serotonin-6 (5-HT) receptors, which are exclusively localized to the central nervous system, is reported to play an important role in learning and memory. Masupirdine is a potent and selective 5-HT receptor antagonist with pro-cognitive properties in animal models of cognition.

View Article and Find Full Text PDF

To improve the understanding of the complex biological process underlying the development of non-alcoholic steatohepatitis (NASH), 3D imaging flow cytometry (3D-IFC) with transmission and side-scattered images were used to characterize hepatic stellate cell (HSC) and liver endothelial cell (LEC) morphology at single-cell resolution. In this study, HSC and LEC were obtained from biopsy-proven NASH subjects with early-stage NASH (F2-F3) and healthy controls. Here, we applied single-cell imaging and 3D digital reconstructions of healthy and diseased cells to analyze a spatially resolved set of morphometric cellular and texture parameters that showed regression with disease progression.

View Article and Find Full Text PDF

Rationale: Ropanicant (SUVN-911) (3-(6-Chloropyridine-3-yloxymethyl)-2-azabicyclo (3.1.0) hexane hydrochloride) is a novel α4β2 nicotinic acetylcholine receptor (nAChR) antagonist being developed for the treatment of depressive disorders.

View Article and Find Full Text PDF

A series of chemical optimizations, which was guided by in vitro affinity at histamine H receptor (H R), modulation of lipophilicity, ADME properties and preclinical efficacy resulted in the identification of 1-[2-(1-cyclobutylpiperidin-4-yloxy)-6,7-dihydro-4H-thiazolo[5,4-c]pyridin-5-yl]propan-1-one (45 e) as a potent and selective (K =4.0 nM) H R inverse agonist. Dipsogenia induced by (R)-α-methylhistamine was dose dependently antagonized by 45 e, confirming its functional antagonism at H R.

View Article and Find Full Text PDF

A series of oxadiazole derivatives were synthesized and evaluated as 5-hydroxytryptamine-4 receptor (5-HTR) partial agonists for the treatment of cognitive deficits associated with Alzheimer's disease. Starting from a reported 5-HTR antagonist, a systematic structure-activity relationship was conducted, which led to the discovery of potent and selective 5-HTR partial agonist 1-isopropyl-3-{5-[1-(3-methoxypropyl) piperidin-4-yl]-[1,3,4]oxadiazol-2-yl}-1H-indazole oxalate (Usmarapride, ). It showed balanced physicochemical-pharmacokinetic properties with robust nonclinical efficacy in cognition models.

View Article and Find Full Text PDF

Rationale: Samelisant (SUVN-G3031) is a potent and selective histamine H3 receptor (H3R) inverse agonist with good brain penetration and oral bioavailability.

Objectives: Pharmacological and neurochemical characterisation to support the utility of Samelisant (SUVN-G3031) in the treatment of sleep-related disorders like narcolepsy.

Methods: Samelisant (SUVN-G3031) was tested in rat brain microdialysis studies for evaluation of modulation in histamine, dopamine and norepinephrine.

View Article and Find Full Text PDF

Background: Central histamine H3 receptors are a family of presynaptic auto and heteroreceptors. Blockade of the presynaptic H3 receptors activates the downstream pathway(s) involved in the processes of learning and memory, making it a potential therapeutic option for ameliorating cognitive dysfunction. Samelisant (SUVN-G3031) is a potent and selective inverse agonist at the H3 receptors.

View Article and Find Full Text PDF

SUVN-G3031 is a potent and selective inverse agonist of Histmine-3 (H) receptor that is being investigated for the treatment of narcolepsy. SUVN-G3031 has high passive permeability, not a substrate for P-glycoprotein, has high plasma unbound fractions and was equally distributed between blood and plasma. Major routes of metabolism in vitro were cyclization (Metabolite A) in microsomes and dealkylation (Metabolite D) in hepatocytes.

View Article and Find Full Text PDF

A series of chemical optimizations guided by in vitro affinity at the α4β2 receptor in combination with selectivity against the α3β4 receptor, pharmacokinetic evaluation, and in vivo efficacy in a forced swim test resulted in identification of 3-(6-chloropyridine-3-yloxymethyl)-2-azabicyclo[3.1.0]hexane hydrochloride (, SUVN-911) as a clinical candidate.

View Article and Find Full Text PDF

A series of chemical optimizations guided by in vitro affinity at a histamine H receptor (HR), physicochemical properties, and pharmacokinetics in rats resulted in identification of N-[4-(1-cyclobutyl-piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride (17v, SUVN-G3031) as a clinical candidate. Compound 17v is a potent (hHR K = 8.73 nM) inverse agonist at HR with selectivity over other 70 targets, Compound 17v has adequate oral exposures and favorable elimination half-lives both in rats and dogs.

View Article and Find Full Text PDF

Research in Alzheimer's disease is going through a big turnaround. New palliative therapies are being reconsidered for the effective management of disease because of setbacks in the development of disease-modifying therapies. Serotonin 6 (5-HT6) receptor has long been pursued as a potential target for the symptomatic treatment of Alzheimer's disease.

View Article and Find Full Text PDF

Alzheimer's disease (AD) is a neurodegenerative disorder that has a higher prevalence and incidence in people older than 60 years. The need for improved AD therapies is unmet as the current therapies are symptomatic with modest efficacy. Partial agonists of the 5-HT receptor (5-HTR) offer both symptomatic and disease-modifying treatments as they shift amyloid-precursor-protein (APP) processing from the amyloidogenic pathway to the nonamyloidogenic pathway by activating the α-secretase enzyme.

View Article and Find Full Text PDF

Optimization of a novel series of 3-(piperazinylmethyl) indole derivatives as 5-hydroxytryptamine-6 receptor (5-HTR) antagonists resulted in identification of 1-[(2-bromophenyl)sulfonyl]-5-methoxy-3-[(4-methyl-1-piperazinyl)methyl]-1H-indole dimesylate monohydrate (5al, SUVN-502) as a clinical candidate for potential treatment of cognitive disorders. It has high affinity at human 5-HTR (K = 2.04 nM) and selectivity over 100 target sites which include receptors, enzymes, peptides, growth factors, ion channels, steroids, immunological factors, second messengers, and prostaglandins.

View Article and Find Full Text PDF

We present a method, Transient Induced Molecular Electronic Spectroscopy (TIMES), to detect protein-ligand interactions without any protein engineering or chemical modification. We developed a physics model for the TIMES signal and mathematically formulated the problem to attain physical insight of protein-ligand interactions without any disturbances by molecular probes, fluorescent labels, or immobilization of molecules. To demonstrate the functionality of this method, we have used the TIMES signals to find the dissociation constants for the affinity of reactions, the shear-stress dependent adsorption time of molecules on surface, and other interesting features of protein-ligand interaction in native conditions.

View Article and Find Full Text PDF

A series of 4-(1-substituted piperidin-4-yloxy) benzamides and 6-(1-substituted piperidin-4-yloxy)-3,4-dihydro-2H-isoquinolin-1-one derivatives have been synthesized and tested for their binding affinity towards H3 receptor. Most of these synthesized compounds have displayed potent binding affinity for H3 receptor when tested in in vitro binding assay. Preliminary SAR studies, functional activity, pharmacokinetic profile and efficacy profile constitute the subject matter of this communication.

View Article and Find Full Text PDF

Alzheimer's disease (AD) is a neurodegenerative disease which has a higher prevalence and incidence in older people. The need for improved AD therapies is unmet. The 5-hydroxytryptamine4 receptor (5-HT4R) partial agonists may be of benefit for both the symptomatic and disease-modifying treatment of cognitive disorders associated with AD.

View Article and Find Full Text PDF

Fermi-Dirac electron thermal excitation is an intrinsic phenomenon that limits functionality of various electron systems. Efforts to manipulate electron thermal excitation have been successful when the entire system is cooled to cryogenic temperatures, typically <1 K. Here we show that electron thermal excitation can be effectively suppressed at room temperature, and energy-suppressed electrons, whose energy distribution corresponds to an effective electron temperature of ~45 K, can be transported throughout device components without external cooling.

View Article and Find Full Text PDF

Our initial findings around aryl sulfonamide series led to N-(3,5-dichloro-2-methoxyphenyl)-3-(1-methylpiperidin-4-ylamino)-4-methoxy benzenesulfonamide as potent and selective 5-HT(6) receptor (5-HT(6)R) antagonist with reasonable pharmacokinetic properties and activity in animal models of cognition. However, lack of brain penetration and P-glycoprotein liability makes this scaffold unsuitable for further development. Our goal was to identify small molecule 5-HT(6)R antagonist with adequate brain penetration, acceptable ADME properties, no P-glycoprotein, and no hERG liability.

View Article and Find Full Text PDF

Devices in which the transport and storage of single electrons are systematically controlled could lead to a new generation of nanoscale devices and sensors. The attractive features of these devices include operation at extremely low power, scalability to the sub-nanometre regime and extremely high charge sensitivity. However, the fabrication of single-electron devices requires nanoscale geometrical control, which has limited their fabrication to small numbers of devices at a time, significantly restricting their implementation in practical devices.

View Article and Find Full Text PDF

We demonstrate a large-scale placement of nanoparticles through a scheme named "electrostatic funneling", in which charged nanoparticles are guided by an electrostatic potential energy gradient and placed on targeted locations with nanoscale precision. The guiding electrostatic structures are defined using current CMOS fabrication technology. The effectiveness of this scheme is demonstrated for a variety of geometries including one-dimensional and zero-dimensional patterns as well as three-dimensional step structures.

View Article and Find Full Text PDF