Education & Certifications
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Doctor of Philosophy, University of Madras, Chemistry-Bioorganic (2006)
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Master of Science, University of Madras, Chemistry (1999)
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Bachelor of Science, University of Madras, Chemistry (1995)
Mohammed Inayathullah
Basic Life Research Scientist, Cardiovascular Institute Operations
Bio
Professional
Work Experience
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Research Scientist, Stanford University (12/1/2010 - Present)
Location
1050 Arastradero Road, Palo Alto, CA 94304, USA
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Postdoctoral Scholar, University of California, Los Angeles (UCLA) (October 2006 - November 2010)
Location
635 Charles E. Young Drive south, Los Angeles, California
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Ph.D Research Scholar, Bioorganic and Neurochemistry Laboratory, CLRI, CSIR. (2000 - 2006)
University of Madras
Location
Adyar, Chennai, India.
Professional Affiliations and Activities
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Editorial Board, Novel Approaches in Drug Designing & Development (NAPDD) (2017 - Present)
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Editorial Board, American Journal of Advanced Drug Delivery (2016 - Present)
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Editorial Board, International Journal of Nanotechnology and Nanomedicine (2016 - Present)
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Editorial Board, Radiology Open Journal (2015 - Present)
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Editorial Board, SM Journal of Clinical and Medical Imaging (2015 - Present)
Publications
All Publications
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BIOMIMETIC ADIPIOSE STEM CELL DRESSING FOR SKIN REGENERATION
WILEY. 2019: A4
View details for Web of Science ID 000463117000011
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TOPICAL FOCAL ADHESION KINASE INHIBITOR PROMOTES SKIN REGENERATION AND SCAR PREVENTION IN A PRECLINICAL PORCINE MODEL
WILEY. 2019: A11–A12
View details for Web of Science ID 000463117000043
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Anti-hyperlipidaemic effects of synthetic analogues of nordihydroguaiaretic acid in dyslipidaemic rats
BRITISH JOURNAL OF PHARMACOLOGY
2019; 176 (3): 369–85
View details for DOI 10.1111/bph.14528
View details for Web of Science ID 000455517100003
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Fidgetin-Like 2 siRNA Enhances the Wound Healing Capability of a Surfactant Polymer Dressing.
Advances in wound care
2019; 8 (3): 91–100
Abstract
Microtubules (MTs) are intracellular polymers that provide structure to the cell, serve as railways for intracellular transport, and regulate many cellular activities, including cell migration. The dynamicity and function of the MT cytoskeleton are determined in large part by its regulatory proteins, including the recently discovered MT severing enzyme Fidgetin-like 2 (FL2). Downregulation of FL2 expression with small interfering RNA (siRNA) results in a more than twofold increase in cell migration rate in vitro as well as translates into improved wound-healing outcomes in in vivo mouse models. Here we utilized a commercially available surfactant polymer dressing (SPD) as a vehicle to deliver FL2 siRNA. To this end we incorporated collagen microparticles containing FL2 siRNA into SPD (SPD-FL2-siRNA) for direct application to the injury site. Topical application of SPD-FL2 siRNA to murine models of full-thickness excision wounds and full-thickness burn wounds resulted in significant improvements in the rate and quality of wound healing, as measured clinically and histologically, compared with controls. Wound healing occurred more rapidly and with high fidelity, resulting in properly organized collagen substructure. Taken together, these findings indicate that the incorporation of FL2 siRNA into existing treatment options is a promising avenue to improve wound outcomes.
View details for PubMedID 30911440
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Optimization of transdermal deferoxamine leads to enhanced efficacy in healing skin wounds.
Journal of controlled release : official journal of the Controlled Release Society
2019
Abstract
Chronic wounds remain a significant burden to both the healthcare system and individual patients, indicating an urgent need for new interventions. Deferoxamine (DFO), an iron-chelating agent clinically used to treat iron toxicity, has been shown to reduce oxidative stress and increase hypoxia-inducible factor-1 alpha (HIF-1α) activation, thereby promoting neovascularization and enhancing regeneration in chronic wounds. However due to its short half-life and adverse side effects associated with systemic absorption, there is a pressing need for targeted DFO delivery. We recently published a preclinical proof of concept drug delivery system (TDDS) which showed that transdermally applied DFO is effective in improving chronic wound healing. Here we present an enhanced TDDS (eTDDS) comprised exclusively of FDA-compliant constituents to optimize drug release and expedite clinical translation. We evaluate the eTDDS to the original TDDS and compare this with other commonly used delivery methods including DFO drip-on and polymer spray applications. The eTDDS displayed excellent physicochemical characteristics and markedly improved DFO delivery into human skin when compared to other topical application techniques. We demonstrate an accelerated wound healing response with the eTDDS treatment resulting in significantly increased wound vascularity, dermal thickness, collagen deposition and tensile strength. Together, these findings highlight the immediate clinical potential of DFO eTDDS to treating diabetic wounds. Further, the topical drug delivery platform has important implications for targeted pharmacologic therapy of a wide range of cutaneous diseases.
View details for DOI 10.1016/j.jconrel.2019.07.009
View details for PubMedID 31299261
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Characterization of Brain Dysfunction Induced by Bacterial Lipopeptides That Alter Neuronal Activity and Network in Rodent Brains
JOURNAL OF NEUROSCIENCE
2018; 38 (50): 10672–91
View details for DOI 10.1523/JNEUROSCI.0825-17.2018
View details for Web of Science ID 000452854200011
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Controlled Delivery of a Focal Adhesion Kinase Inhibitor Results in Accelerated Wound Closure with Decreased Scar Formation
JOURNAL OF INVESTIGATIVE DERMATOLOGY
2018; 138 (11): 2452–60
View details for DOI 10.1016/j.jid.2018.04.034
View details for Web of Science ID 000447794000026
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Characterization of brain dysfunction induced by bacterial lipopeptides that alter neuronal activity and network in rodent brains.
The Journal of neuroscience : the official journal of the Society for Neuroscience
2018
Abstract
The immunopathological states of the brain induced by bacterial lipoproteins have been well-characterized by employing biochemical and histological assays. However, these studies have limitations in determining functional states of damaged brains involving aberrant synaptic activity and network, which makes it difficult to diagnose brain disorders during bacterial infection. To address this, we investigated the effect of Pam3CSK4 (PAM), a synthetic bacterial lipopeptide, on synaptic dysfunction of female mice brains and cultured neurons in parallel. Our functional brain imaging using PET with [18F]-FDG and [18F]-FMZ revealed the brain dysfunction induced by PAM is closely aligned to disruption of neurotransmitter-related neuronal activity and functional correlation in the region of the limbic system rather than to decrease of metabolic activity of neurons in the injection area. This finding was verified by in vivo tissue experiments that analyzed synaptic and dendritic alterations in the regions where PET imaging showed abnormal neuronal activity and network. Recording of synaptic activity also revealed that PAM reorganized synaptic distribution and decreased synaptic plasticity in hippocampus. Further study using in vitro neuron cultures demonstrated that PAM decreased the number of presynapses and the frequency of mEPSC, which suggests PAM disrupts neuronal function by damaging presynapses exclusively. We also showed PAM caused aggregation of synapses around dendrites, which may have caused no significant change in expression level of synaptic proteins while synaptic number and function was impaired by PAM. New findings of this study could provide a useful guide for diagnosis and treatment of brain disorders specific to bacterial infection.SIGNIFICANCE STATEMENTIt is challenging to diagnose brain disorders caused by bacterial infection because neural damage induced by bacterial products involves non-specific neurological symptoms, which is rarely detected by laboratory tests with low spatiotemporal resolution. To better understand brain pathology, it is essential to detect functional abnormalities of brain over time. To this end, we investigated characteristic patterns of altered neuronal integrity and functional correlation between various regions in mice brains injected with bacterial lipopeptides by using PET with a goal to apply new findings to diagnosis of brain disorder specific to bacterial infection. In addition, we analyzed altered synaptic density and function using both in vivo and in vitro experimental models to understand how bacterial lipopeptides impair brain function and network.
View details for PubMedID 30381406
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Anti-Hyperlipidemic Effects of Synthetic Analogs of Nordihydroguaiaretic acid (NDGA) in Dyslipidemic Rats.
British journal of pharmacology
2018
Abstract
BACKGROUND AND PURPOSE: Previous studies have shown that Creosote bush-derived NDGA exerts beneficial actions on the key components of MetS including dyslipidemia, insulin resistance and hypertension in several relevant rodent models. Here we synthesized and screened a total of 6 antihyperlipidemic analogs of NDGA and tested their efficacy against hepatic lipid metabolism in a high-fructose diet (HFrD) fed dyslipidemic rat model.EXPERIMENTAL APPROACH: HFrD fed Sprague-Dawley (SD) treated with NDGA or one of the 6 analogs were used here. Serum samples were analyzed for blood metabolites, whereas liver samples were quantified for changes in various mRNA levels by real-time RT-PCR.KEY RESULTS: Oral gavage of HFrD-fed rats for 4 days with NDGA analogs 1 and 2 (100 mg/kg, once daily) suppressed the hepatic triglyceride content, whereas treatment of rats with NDGA analogs 2, 3 and 4, like NDGA, decreased the plasma triglyceride levels by 70-75%. qRT-PCR measurements demonstrated that among the NDGA analogs 1, 2, 4 and 5, analog 4 was most effective in inhibiting the mRNA levels of some key enzymes and transcription factors involved in lipogenesis. All four analogs almost equally inhibited the key genes involved in triglyceride synthesis and fatty acid elongation. Unlike NDGA, none of the analogs affected the genes of hepatic fatty acid oxidation or transport CONCLUSIONS AND IMPLICATIONS: Our data suggest that NDGA analogs 1, 2, 4 and 5, particularly analog 4, exert their anti-hyperlipidemic actions by negatively targeting genes of key enzymes and transcription factors involved in lipogenesis, triglyceride synthesis and fatty acid elongation. These analogs have therapeutic implications.
View details for PubMedID 30374952
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Fidgetin-Like 2 siRNA Enhances the Wound Healing Capability of a Surfactant Polymer Dressing
ADVANCES IN WOUND CARE
2018
View details for DOI 10.1089/wound.2018.0827
View details for Web of Science ID 000448369800001
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Cytokines as therapeutic agents and targets in heart disease
CYTOKINE & GROWTH FACTOR REVIEWS
2018; 43: 54–68
View details for DOI 10.1016/j.cytogfr.2018.08.003
View details for Web of Science ID 000447733300007
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Deferoxamine Can Prevent Pressure Ulcers and Accelerate Healing in Aged Mice.
Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society
2018
Abstract
Chronic wounds are a significant medical and economic problem worldwide. Individuals over the age of 65 are particularly vulnerable to pressure ulcers and impaired wound healing. With this demographic growing rapidly there is a need for effective treatments. We have previously shown that defective hypoxia signaling through destabilization of the master hypoxia-inducible factor 1alpha (HIF-1alpha) underlies impairments in both aging and diabetic wound healing. To stabilize HIF-1alpha, we developed a transdermal delivery system of the FDA-approved small molecule deferoxamine (DFO) and found that transdermal DFO could both prevent and treat ulcers in diabetic mice. Here, we show that transdermal DFO can similarly prevent pressure ulcers and normalize aged wound healing. Enhanced wound healing by DFO is brought about by stabilization of HIF-1alpha and improvements in neovascularization. Transdermal DFO can be rapidly translated into the clinic and may represent a new approach to prevent and treat pressure ulcers in aged patients. This article is protected by copyright. All rights reserved.
View details for PubMedID 30152571
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Cytokines as therapeutic agents and targets in heart disease.
Cytokine & growth factor reviews
2018
Abstract
Cytokine therapies have emerged during the past decade as promising noninvasive treatments for heart disease. In general, current drug treatments are directed towards symptom control and prevention of disease progression; however, many agents also produce cause side effects that alter quality of life. Cytokine based therapies have the potential to reduce post-infarct heart failure and chronic ischemia by stimulating the proliferation and differentiation of endothelial cells and bone marrow hematopoietic stem cells and mobilizing these cells toward ischemic tissue. In turn, these mobilized cell populations contribute to myocardial regeneration. In contrast, over-expression of several cytokines has been linked to a variety of heart diseases; thus, therapies targeting and monitoring these cytokines are of great interest. Here we summarize results from clinical studies on cytokines as therapeutic agents or therapeutic targets in the treatment for heart disease as well as cytokines involved in the evolution of heart disease.
View details for PubMedID 30170892
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TOPICAL DELIVERY OF A FOCAL ADHESION KINASE INHIBITOR RESULTS IN ACCELERATED WOUND HEALING WITH REDUCED SCARRING IN A PORCINE WOUND MODEL
WILEY. 2018: A13
View details for Web of Science ID 000451464000057
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Deferoxamine can prevent pressure ulcers and accelerate healing in aged mice
WOUND REPAIR AND REGENERATION
2018; 26 (3): 300–305
View details for DOI 10.1111/wrr.12667
View details for Web of Science ID 000451719400006
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PEG/Dextran Double Layer Influences Fe Ion Release and Colloidal Stability of Iron Oxide Nanoparticles.
Scientific reports
2018; 8 (1): 4286
Abstract
Despite preliminary confidence on biosafety of polymer coated iron oxide nanoparticles (SPIONs), toxicity concerns have hampered their clinical translation. SPIONs toxicity is known to be due to catalytic activity of their surface and release of toxic Fe ions originating from the core biodegradation, leading to the generation of reactive oxygen species (ROS). Here, we hypothesized that a double-layer polymeric corona comprising of dextran as an interior, and polyethylene glycol (PEG) as an exterior layer better shields the core SPIONs. We found that ROS generation was cell specific and depended on SPIONs concentration, although it was reduced by sufficient PEG immobilization or 100 µM deferoxamine. 24 h following injection, PEGylated samples showed reduction of biodistribution in liver, heterogenous biodistribution profile in spleen, and no influence on NPs blood retention. Sufficient surface masking or administration of deferoxamine could be beneficial strategies in designing and clinical translation of future biomedical SPIONs.
View details for PubMedID 29523826
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In vitro and in vivo evaluation of cephalosporins for the treatment of Lyme disease.
Drug design, development and therapy
2018; 12: 2915–21
Abstract
Lyme disease accounts for >90% of all vector-borne disease cases in the United States and affect ~300,000 persons annually in North America. Though traditional tetracycline antibiotic therapy is generally prescribed for Lyme disease, still 10%-20% of patients treated with current antibiotic therapy still show lingering symptoms.In order to identify new drugs, we have evaluated four cephalosporins as a therapeutic alternative to commonly used antibiotics for the treatment of Lyme disease by using microdilution techniques like minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). We have determined the MIC and MBC of four drugs for three Borrelia burgdorferi s.s strains namely CA8, JLB31 and NP40. The binding studies were performed using in silico analysis.The MIC order of the four drugs tested is cefoxitin (1.25 µM/mL) > cefamandole (2.5 µM/mL), > cefuroxime (5 µM/mL) > cefapirin (10 µM/mL). Among the drugs that are tested in this study using in vivo C3H/HeN mouse model, cefoxitin effectively kills B. burgdorferi. The in silico analysis revealed that all four cephalosporins studied binds effectively to B. burgdorferi proteins, SecA subunit penicillin-binding protein (PBP) and Outer surface protein E (OspE).Based on the data obtained, cefoxitin has shown high efficacy killing B. burgdorferi at concentration of 1.25 µM/mL. In addition to it, cefoxitin cleared B. burgdorferi infection in C3H/HeN mice model at 20 mg/kg.
View details for PubMedID 30254421
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In vitro and in vivo evaluation of cephalosporins for the treatment of Lyme disease
DRUG DESIGN DEVELOPMENT AND THERAPY
2018; 12: 2915–21
View details for DOI 10.2147/DDDT.S164966
View details for Web of Science ID 000444298700004
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Transdermal Deferoxamine Significantly Enhances Healing of Sickle Cell Ulcers
WILEY. 2018: A11
View details for Web of Science ID 000430308600039
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Topical Delivery of a Focal Adhesion Kinase Inhibitor Results in Accelerated Wound Healing with Reduced Scarring in a Porcine Wound Model
WILEY. 2018: A33
View details for Web of Science ID 000430308600139
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Transdermal Deferoxamine Enhances Wound Healing in Aged Mice
WILEY. 2018: A10
View details for Web of Science ID 000430308600036
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Controlled Delivery of a Focal Adhesion Kinase Inhibitor Results in Accelerated Wound Closure with Decreased Scar Formation.
The Journal of investigative dermatology
2018
Abstract
Formation of scars following wounding or trauma represents a significant healthcare burden costing the economy billions of dollars every year. Activation of focal adhesion kinase (FAK) has been shown to play a pivotal role in transducing mechanical signals to elicit fibrotic responses and scar formation during wound repair. We have previously shown that inhibition of FAK using local injections of a small molecule FAK inhibitor (FAKI) can attenuate scar development in a hypertrophic scar model. Clinical translation of FAKI therapy has been challenging, however, due to the lack of an effective drug delivery system for extensive burn injuries, blast injuries, and large excisional injuries. To address this issue, we have developed a pullulan collagen-based hydrogel to deliver FAKI to excisional and burn wounds in mice. Specifically, two distinct drug-laden hydrogels were developed for rapid or sustained release of FAKI for treatment of burn wounds and excisional wounds, respectively. Controlled delivery of FAKI via pullulan collagen hydrogels accelerated wound healing, reduced collagen deposition and activation of scar forming myofibroblasts in both wound healing models. Our study highlights a biomaterial-based drug delivery approach for wound and scar management that has significant translational implications.
View details for PubMedID 29775632
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Prolonged survival of transplanted stem cells after ischaemic injury via the slow release of pro-survival peptides from a collagen matrix.
Nature biomedical engineering
2018; 2 (2): 104–13
Abstract
Stem-cell-based therapies hold considerable promise for regenerative medicine. However, acute donor-cell death within several weeks after cell delivery remains a critical hurdle for clinical translation. Co-transplantation of stem cells with pro-survival factors can improve cell engraftment, but this strategy has been hampered by the typically short half-lives of the factors and by the use of Matrigel and other scaffolds that are not chemically defined. Here, we report a collagen-dendrimer biomaterial crosslinked with pro-survival peptide analogues that adheres to the extracellular matrix and slowly releases the peptides, significantly prolonging stem cell survival in mouse models of ischaemic injury. The biomaterial can serve as a generic delivery system to improve functional outcomes in cell-replacement therapy.
View details for PubMedID 29721363
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Microhemorrhage-associated tissue iron enhances the risk forAspergillus fumigatusinvasion in a mouse model of airway transplantation.
Science translational medicine
2018; 10 (429)
Abstract
Invasive pulmonary disease due to the moldAspergillus fumigatuscan be life-threatening in lung transplant recipients, but the risk factors remain poorly understood. To study this process, we used a tracheal allograft mouse model that recapitulates large airway changes observed in patients undergoing lung transplantation. We report that microhemorrhage-related iron content may be a major determinant ofA. fumigatusinvasion and, consequently, its virulence. Invasive growth was increased during progressive alloimmune-mediated graft rejection associated with high concentrations of ferric iron in the graft. The role of iron inA. fumigatusinvasive growth was further confirmed by showing that this invasive phenotype was increased in tracheal transplants from donor mice lacking the hemochromatosis gene (Hfe -/- ). The invasive phenotype was also increased in mouse syngrafts treated with topical iron solution and in allograft recipients receiving deferoxamine, a chelator that increases iron bioavailability to the mold. The invasive growth of the iron-intolerantA. fumigatusdouble-knockout mutant (ΔsreA/ΔcccA) was lower than that of the wild-type mold. Alloimmune-mediated microvascular damage and iron overload did not appear to impair the host's immune response. In human lung transplant recipients, positive staining for iron in lung transplant tissue was more commonly seen in endobronchial biopsy sections from transplanted airways than in biopsies from the patients' own airways. Collectively, these data identify iron as a major determinant ofA. fumigatusinvasive growth and a potential target to treat or preventA. fumigatusinfections in lung transplant patients.
View details for PubMedID 29467298
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Nordihydroguaiaretic acid, a lignan from Larrea tridentata (Creosote bush) protects against ALIOS diet-induced metabolic dysfunction in mice.
The Journal of pharmacology and experimental therapeutics
2018
Abstract
To determine the effects of NDGA on metabolic and molecular changes in response to feeding mice typical American fast food or Western diet, mice were fed with ALIOS diet and subjected to metabolic analysis. Male C57BL/6J mice were randomly assigned to: ALIOS, ALIOS + NDGA, or control diet and maintained on the specific diet for 8 weeks. Mice fed ALIOS diet, showed increased body, liver and epididymal fat pad weight, plasma ALT and AST levels (a measure of liver injury), and liver triglyceride (TG) content. Co-administration of NDGA normalized body and epididymal fat pad weight, ALT and AST levels, and liver TG. NDGA treatment also improved insulin sensitivity but not glucose intolerance in ALIOS diet fed mice. In ALIOS diet fed mice, NDGA supplementation induced PPARα (the master regulator of fatty acid oxidation) and mRNA levels of Cpt1c and Cpt2, key genes involved in fatty acid oxidation as compared to ALIOS diet. NDGA significantly reduced liver ER stress response CHOP protein, as compared to chow or ALIOS diet and also ameliorated ALIOS diet-induced elevation of apoptosis signaling protein, CASP3. Likewise, NDGA downregulated the ALIOS-diet induced mRNA levels of Pparg, Fasn, and Dgat2. NDGA treatment of ALIOS fed mice upregulated the hepatic expression of antioxidant enzymes, GPX4 and PRDX3 proteins. In conclusion, we provide evidence that NDGA improves metabolic dysregulation by simultaneously modulating PPARα transcription factor and key genes involved in fatty acid oxidation, key antioxidant and lipogenic enzymes, and apoptosis and ER stress signaling pathways.
View details for PubMedID 29472517
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Screening of NCI-DTP library to identify new drug candidates for Borrelia burgdorferi.
journal of antibiotics
2017; 70 (3): 308-312
View details for DOI 10.1038/ja.2016.131
View details for PubMedID 27826144
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Nanomaterials engineering for drug delivery: a hybridization approach
Journal of Materials Chemistry B
2017; 5 (22): 3995-4018
View details for DOI 10.1039/C6TB03247H
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Identification of key regions and residues controlling Aβ folding and assembly.
Scientific reports
2017; 7 (1): 12434
Abstract
Amyloid β-protein (Aβ) assembly is hypothesized to be a seminal neuropathologic event in Alzheimer's disease (AD). We used an unbiased D-amino acid substitution strategy to determine structure-assembly relationships of 76 different Aβ40 and Aβ42 peptides. We determined the effects of the substitutions on peptide oligomerization, secondary structure dynamics, fibril assembly dynamics, and fibril morphology. Our experiments revealed that the assembly of Aβ42 was more sensitive to chiral substitutions than was Aβ40 assembly. Substitutions at identical positions in the two peptides often, but not always, produced the same effects on assembly. Sites causing substantial effects in both Aβ40 and Aβ42 include His14, Gln15, Ala30, Ile31, Met35, and Val36. Sites whose effects were unique to Aβ40 include Lys16, Leu17, and Asn 27, whereas sites unique to Aβ42 include Phe20 and Ala21. These sites may be appropriate targets for therapeutic agents that inhibit or potentiate, respectively, these effects.
View details for PubMedID 28974765
View details for PubMedCentralID PMC5626695
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Endothelial APLNR regulates tissue fatty acid uptake and is essential for apelin's glucose-lowering effects.
Science translational medicine
2017; 9 (407)
Abstract
Treatment of type 2 diabetes mellitus continues to pose an important clinical challenge, with most existing therapies lacking demonstrable ability to improve cardiovascular outcomes. The atheroprotective peptide apelin (APLN) enhances glucose utilization and improves insulin sensitivity. However, the mechanism of these effects remains poorly defined. We demonstrate that the expression of APLNR (APJ/AGTRL1), the only known receptor for apelin, is predominantly restricted to the endothelial cells (ECs) of multiple adult metabolic organs, including skeletal muscle and adipose tissue. Conditional endothelial-specific deletion of Aplnr (Aplnr(ECKO) ) resulted in markedly impaired glucose utilization and abrogation of apelin-induced glucose lowering. Furthermore, we identified inactivation of Forkhead box protein O1 (FOXO1) and inhibition of endothelial expression of fatty acid (FA) binding protein 4 (FABP4) as key downstream signaling targets of apelin/APLNR signaling. Both the Apln(-/-) and Aplnr(ECKO) mice demonstrated increased endothelial FABP4 expression and excess tissue FA accumulation, whereas concurrent endothelial Foxo1 deletion or pharmacologic FABP4 inhibition rescued the excess FA accumulation phenotype of the Apln(-/-) mice. The impaired glucose utilization in the Aplnr(ECKO) mice was associated with excess FA accumulation in the skeletal muscle. Treatment of these mice with an FABP4 inhibitor abrogated these metabolic phenotypes. These findings provide mechanistic insights that could greatly expand the therapeutic repertoire for type 2 diabetes and related metabolic disorders.
View details for PubMedID 28904225
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Nanoparticles hybridization to engineer biomaterials for drug delivery
Nanobiomaterials Science, Development and Evaluation
Elsevier. 2017: 147–161
View details for DOI 10.1016/B978-0-08-100963-5.00008-2
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Attenuation of synaptic toxicity and MARK4/PAR1-mediated Tau phosphorylation by methylene blue for Alzheimer's disease treatment
SCIENTIFIC REPORTS
2016; 6
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by genotypic and phenotypic heterogeneity. Critical components of the two AD pathological pathways, Aβ-amyloidosis and Tauopathy, have been considered as therapeutic targets. Among them, much effort is focused on aberrant Tau phosphorylation and targeting Tau-phosphorylating kinases. Methylene blue (MB), a phenothiazine dye that crosses the blood-brain barrier, has been shown to hit multiple molecular targets involved in AD and have beneficial effects in clinical studies. Here we present evidence that microtubule affinity-regulating kinase (MARK4) is a novel target of MB. MB partially rescued the synaptic toxicity in Drosophila larva overexpressing PAR1 (MARK analog). In 293T culture, MB decreased MARK4-mediated Tau phosphorylation in a dose dependent manner. Further studies revealed a two-fold mechanism by MB including down-regulation of MARK4 protein level through ubiquitin-proteasome pathway and inhibition of MARK4 kinase activity in vitro. This study highlights the importance of MARK4 as a viable target for Tauopathy and provides fresh insight into the complex mechanism used by MB to treat AD.
View details for DOI 10.1038/srep34784
View details for PubMedID 27708431
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Enhanced Electrochemical Sensing with Carbon Nanotubes Modified with Bismuth and Magnetic Nanoparticles in a Lab-on-a-Chip
CHEMNANOMAT
2016; 2 (9): 904-910
Abstract
Iron plays an especially important role in human physiological functions and pathological impairments. The superior properties of carbon nanotubes (CNTs) and their modification with bismuth and magnetic nanoparticles as developed in this work have led to an extraordinary and novel material to facilitate ultrasensitive detection in the nanomolar range. Here, we present the development of an electrochemical sensor for detection of ferrous (Fe(2+)) and ferric (Fe(3+)) iron by means of CNTs modified with bismuth and magnetic nanoparticles for higher sensitivity of detection. The sensor fabrication includes microfabrication methodologies, soft lithography, and electrodeposition. Cyclic voltammetry and differential pulse voltammetry are used for the electroanalytical studies and detection of the ions in samples. The sensor has a dynamic range of detection from 0.01 nm to 10 mm. The performance of the sensor with modified CNTs was explored for sensitivity and specificity. CNTs, modified with bismuth and magnetic nanoparticles by means of electrodeposition, enhanced the detection limit significantly down to 0.01 nm.
View details for DOI 10.1002/cnma.201600174
View details for Web of Science ID 000383766800009
View details for PubMedCentralID PMC5110256
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Conformational dynamics of a hydrophobic prion fragment (113-127) in different pH and osmolyte solutions
NEUROPEPTIDES
2016; 57: 9-14
Abstract
Prion diseases are characterized by a conformational change in prion protein from its native state into beta-sheet rich aggregates that are neurotoxic. The central domain that contain a highly conserved hydrophobic region of the protein play an important role in the toxicity. The conformation of the proteins is largely influenced by various solvent environments. Here we report results of study of hydrophobic prion fragment peptide PrP(113-127) under different pH and osmolytes solution conditions. The secondary structure and the folding of PrP(113-127) was determined using circular dichroism and fluorescence spectroscopic methods. The results indicate that PrP(113-127) adopts a random coil conformation in aqueous buffer at neutral pH and that converted into beta sheet on aging. Even though the initial random coil conformation was similar in different pH conditions, the acidic as well as basic pH conditions delays the conformational transition to beta sheet. FRET results indicate that the distance between N and C-terminal regions increased on aging due to unfolding by self-assembly of the peptide into an organized beta sheet structure. Presence of osmolytes, prevented or decelerated the aggregation process of PrP(113-127) peptide.
View details for DOI 10.1016/j.npep.2016.02.004
View details for Web of Science ID 000378193100002
View details for PubMedID 26919915
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Effect of osmolytes on the conformation and aggregation of some amyloid peptides: CD spectroscopic data
DATA IN BRIEF
2016; 7: 1643–51
View details for DOI 10.1016/j.dib.2016.04.070
View details for Web of Science ID 000453166200259
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Effect of osmolytes on the conformation and aggregation of some amyloid peptides: CD spectroscopic data.
Data in brief
2016; 7: 1643-1651
Abstract
Protein misfolding and aggregation are responsible for a large number of diseases called protein conformational diseases or disorders that include Alzheimer׳s disease, Huntington׳s diseases, Prion related encephalopathies and type-II diabetes (http://dx.doi.org/10.1038/35041139) (Kopito and Ron, 2000) [1]. A variety of studies have shown that some small organic molecules, known as osmolytes have the ability to stabilize native conformation of proteins and prevent misfolding and aggregation (http://www.la-press.com/article.php?article_id=447) (Zhao et al., 2008) [2]. It has been shown that certain short segment or fragment of respective proteins can also form amyloids, and the segments also promote the aggregation in the full-length protein (http://dx.doi.org/10.2174/0929867023369187) (Gazit, 2002) [3]. This article presents circular dichroism spectroscopic data on conformational analysis and effect of osmolytes on Aβ peptide fragments, different lengths of polyglutamine peptide and the amyloidogenic segment of islet amyloid polypeptide.
View details for DOI 10.1016/j.dib.2016.04.070
View details for PubMedID 27222868
View details for PubMedCentralID PMC4872718
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Self-assembly and sequence length dependence on nanofibrils of polyglutamine peptides
NEUROPEPTIDES
2016; 57: 71-83
Abstract
Huntington's disease (HD) is recognized as a currently incurable, inherited neurodegenerative disorder caused by the accumulation of misfolded polyglutamine (polyQ) peptide aggregates in neuronal cells. Yet, the mechanism by which newly formed polyQ chains interact and assemble into toxic oligomeric structures remains a critical, unresolved issue. In order to shed further light on the matter, our group elected to investigate the folding of polyQ peptides - examining glutamine repeat lengths ranging from 3 to 44 residues. To characterize these aggregates we employed a diverse array of technologies, including: nuclear magnetic resonance; circular dichroism; Fourier transform infrared spectroscopy; fluorescence resonance energy transfer (FRET), and atomic force microscopy. The data we obtained suggest that an increase in the number of glutamine repeats above 14 residues results in disordered loop structures, with different repeat lengths demonstrating unique folding characteristics. This differential folding manifests in the formation of distinct nano-sized fibrils, and on this basis, we postulate the idea of 14 polyQ repeats representing a critical loop length for neurotoxicity - a property that we hope may prove amenable to future therapeutic intervention. Furthermore, FRET measurements on aged assemblages indicate an increase in the end-to-end distance of the peptide with time, most probably due to the intermixing of individual peptide strands within the nanofibril. Further insight into this apparent time-dependent reorganization of aggregated polyQ peptides may influence future disease modeling of polyQ-related proteinopathies, in addition to directing novel clinical innovations.
View details for DOI 10.1016/j.npep.2016.01.011
View details for Web of Science ID 000378193100010
View details for PubMedID 26874369
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Identification of new drug candidates against Borrelia burgdorferi using high-throughput screening
DRUG DESIGN DEVELOPMENT AND THERAPY
2016; 10: 1307-1322
Abstract
Lyme disease is the most common zoonotic bacterial disease in North America. It is estimated that >300,000 cases per annum are reported in USA alone. A total of 10%-20% of patients who have been treated with antibiotic therapy report the recrudescence of symptoms, such as muscle and joint pain, psychosocial and cognitive difficulties, and generalized fatigue. This condition is referred to as posttreatment Lyme disease syndrome. While there is no evidence for the presence of viable infectious organisms in individuals with posttreatment Lyme disease syndrome, some researchers found surviving Borrelia burgdorferi population in rodents and primates even after antibiotic treatment. Although such observations need more ratification, there is unmet need for developing the therapeutic agents that focus on removing the persisting bacterial form of B. burgdorferi in rodent and nonhuman primates. For this purpose, high-throughput screening was done using BacTiter-Glo assay for four compound libraries to identify candidates that stop the growth of B. burgdorferi in vitro. The four chemical libraries containing 4,366 compounds (80% Food and Drug Administration [FDA] approved) that were screened are Library of Pharmacologically Active Compounds (LOPAC1280), the National Institutes of Health Clinical Collection, the Microsource Spectrum, and the Biomol FDA. We subsequently identified 150 unique compounds, which inhibited >90% of B. burgdorferi growth at a concentration of <25 µM. These 150 unique compounds comprise many safe antibiotics, chemical compounds, and also small molecules from plant sources. Of the 150 unique compounds, 101 compounds are FDA approved. We selected the top 20 FDA-approved molecules based on safety and potency and studied their minimum inhibitory concentration and minimum bactericidal concentration. The promising safe FDA-approved candidates that show low minimum inhibitory concentration and minimum bactericidal concentration values can be chosen as lead molecules for further advanced studies.
View details for DOI 10.2147/DDDT.S101486
View details for Web of Science ID 000373575000001
View details for PubMedID 27103785
View details for PubMedCentralID PMC4827596
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Enhanced Electrochemical Sensing with Carbon Nanotubes Modified with Bismuth and Magnetic Nanoparticles in a Lab-on-a-Chip.
ChemNanoMat : chemistry of nanomaterials for energy, biology and more
2016; 2 (9): 904–10
Abstract
Iron plays an especially important role in human physiological functions and pathological impairments. The superior properties of carbon nanotubes (CNTs) and their modification with bismuth and magnetic nanoparticles as developed in this work have led to an extraordinary and novel material to facilitate ultrasensitive detection in the nanomolar range. Here, we present the development of an electrochemical sensor for detection of ferrous (Fe(2+)) and ferric (Fe(3+)) iron by means of CNTs modified with bismuth and magnetic nanoparticles for higher sensitivity of detection. The sensor fabrication includes microfabrication methodologies, soft lithography, and electrodeposition. Cyclic voltammetry and differential pulse voltammetry are used for the electroanalytical studies and detection of the ions in samples. The sensor has a dynamic range of detection from 0.01 nm to 10 mm. The performance of the sensor with modified CNTs was explored for sensitivity and specificity. CNTs, modified with bismuth and magnetic nanoparticles by means of electrodeposition, enhanced the detection limit significantly down to 0.01 nm.
View details for PubMedID 27857882
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Transdermal Delivery of Functional Collagen Via Polyvinylpyrrolidone Microneedles
ANNALS OF BIOMEDICAL ENGINEERING
2015; 43 (12): 2978-2990
Abstract
Collagen makes up a large proportion of the human body, particularly the skin. As the body ages, collagen content decreases, resulting in wrinkled skin and decreased wound healing capabilities. This paper presents a method of delivering type I collagen into porcine and human skin utilizing a polyvinylpyrrolidone microneedle delivery system. The microneedle patches were made with concentrations of 1, 2, 4, and 8% type I collagen (w/w). Microneedle structures and the distribution of collagen were characterized using scanning electron microscopy and confocal microscopy. Patches were then applied on the porcine and human skin, and their effectiveness was examined using fluorescence microscopy. The results illustrate that this microneedle delivery system is effective in delivering collagen I into the epidermis and dermis of porcine and human skin. Since the technique presented in this paper is quick, safe, effective and easy, it can be considered as a new collagen delivery method for cosmetic and therapeutic applications.
View details for DOI 10.1007/s10439-015-1353-0
View details for PubMedID 26066056
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A Thermo-Sensitive Delivery Platform for Topical Administration of Inflammatory Bowel Disease Therapies.
Gastroenterology
2015; 149 (1): 52-55 e2
Abstract
Systemic therapies for inflammatory bowel disease are associated with increased risk of infections and malignancies. Topical therapies reduce systemic exposure, but can be difficult to retain or have limited proximal distribution. To mitigate these issues, we developed a thermo-sensitive platform, using a polymer-based system that is liquid at room temperature but turns into a viscous gel upon reaching body temperature. Following rectal administration to mice with dextran sulphate sodium-induced colitis, the platform carrying budesonide or mesalamine becomes more viscoelastic near body temperature. Mice given the drug-containing platform gained more weight and had reduced histologic and biologic features of colitis than mice given the platform alone or liquid drugs via enema. Image analysis showed that enemas delivered with and without the platform reached similar distances in the colons of mice, but greater colonic retention was achieved by using the platform.
View details for DOI 10.1053/j.gastro.2015.04.002
View details for PubMedID 25863215
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Transdermal deferoxamine prevents pressure-induced diabetic ulcers.
Proceedings of the National Academy of Sciences of the United States of America
2015; 112 (1): 94-99
Abstract
There is a high mortality in patients with diabetes and severe pressure ulcers. For example, chronic pressure sores of the heels often lead to limb loss in diabetic patients. A major factor underlying this is reduced neovascularization caused by impaired activity of the transcription factor hypoxia inducible factor-1 alpha (HIF-1α). In diabetes, HIF-1α function is compromised by a high glucose-induced and reactive oxygen species-mediated modification of its coactivator p300, leading to impaired HIF-1α transactivation. We examined whether local enhancement of HIF-1α activity would improve diabetic wound healing and minimize the severity of diabetic ulcers. To improve HIF-1α activity we designed a transdermal drug delivery system (TDDS) containing the FDA-approved small molecule deferoxamine (DFO), an iron chelator that increases HIF-1α transactivation in diabetes by preventing iron-catalyzed reactive oxygen stress. Applying this TDDS to a pressure-induced ulcer model in diabetic mice, we found that transdermal delivery of DFO significantly improved wound healing. Unexpectedly, prophylactic application of this transdermal delivery system also prevented diabetic ulcer formation. DFO-treated wounds demonstrated increased collagen density, improved neovascularization, and reduction of free radical formation, leading to decreased cell death. These findings suggest that transdermal delivery of DFO provides a targeted means to both prevent ulcer formation and accelerate diabetic wound healing with the potential for rapid clinical translation.
View details for DOI 10.1073/pnas.1413445112
View details for PubMedID 25535360
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[Pyr-1]-Apelin-13 delivery via nano-liposomal encapsulation attenuates pressure overload-induced cardiac dysfunction
BIOMATERIALS
2015; 37: 289-298
Abstract
Nanoparticle-mediated sustained delivery of therapeutics is one of the highly effective and increasingly utilized applications of nanomedicine. Here, we report the development and application of a drug delivery system consisting of polyethylene glycol (PEG)-conjugated liposomal nanoparticles as an efficient in vivo delivery approach for [Pyr1]-apelin-13 polypeptide. Apelin is an adipokine that regulates a variety of biological functions including cardiac hypertrophy and hypertrophy-induced heart failure. The clinical use of apelin has been greatly impaired by its remarkably short half-life in circulation. Here, we investigate whether [Pyr1]-apelin-13 encapsulation in liposome nanocarriers, conjugated with PEG polymer on their surface, can prolong apelin stability in the blood stream and potentiate apelin beneficial effects in cardiac function. Atomic force microscopy and dynamic light scattering were used to assess the structure and size distribution of drug-laden nanoparticles. [Pyr1]-apelin-13 encapsulation in PEGylated liposomal nanocarriers resulted in sustained and extended drug release both in vitro and in vivo. Moreover, intraperitoneal injection of [Pyr1]-apelin-13 nanocarriers in a mouse model of pressure-overload induced heart failure demonstrated a sustainable long-term effect of [Pyr1]-apelin-13 in preventing cardiac dysfunction. We concluded that this engineered nanocarrier system can serve as a delivery platform for treating heart injuries through sustained bioavailability of cardioprotective therapeutics.
View details for DOI 10.1016/j.biomaterials.2014.08.045
View details for Web of Science ID 000346541100028
View details for PubMedID 25443792
- Recent Developments in Diffusion Tensor Imaging of Brain Radiol Open J. 2015; 1 (1): 12
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Recent Developments in Diffusion Tensor Imaging of Brain.
Radiology - open journal
2015; 1 (1): 1-12
Abstract
Magnetic resonance imaging (MRI) has come to be known as a unique radiological imaging modality because of its ability to perform tomographic imaging of body without the use of any harmful ionizing radiation. The radiologists use MRI to gain insight into the anatomy of organs, including the brain, while biomedical researchers explore the modality to gain better understanding of the brain structure and function. However, due to limited resolution and contrast, the conventional MRI fails to show the brain microstructure. Diffusion tensor imaging (DTI) harnesses the power of conventional MRI to deduce the diffusion dynamics of water molecules within the tissue and indirectly create a three-dimensional sketch of the brain anatomy. DTI enables visualization of brain tissue microstructure, which is extremely helpful in understanding various neuropathologies and neurodegenerative disorders. In this review, we briefly discuss the background and operating principles of DTI, followed by current trends in DTI applications for biomedical and clinical investigation of various brain diseases and disorders.
View details for PubMedID 27077135
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Borreliacidal activity of Borrelia metal transporter A (BmtA) binding small molecules by manganese transport inhibition
DRUG DESIGN DEVELOPMENT AND THERAPY
2015; 9: 805-815
Abstract
Borrelia burgdorferi, the causative agent of Lyme disease, utilizes manganese (Mn) for its various metabolic needs. We hypothesized that blocking Mn transporter could be a possible approach to inhibit metabolic activity of this pathogen and eliminate the infection. We used a combination of in silico protein structure prediction together with molecular docking to target the Borrelia metal transporter A (BmtA), a single known Mn transporter in Borrelia and screened libraries of FDA approved compounds that could potentially bind to the predicted BmtA structure with high affinity. Tricyclic antihistamines such as loratadine, desloratadine, and 3-hydroxydesloratadine as well as yohimbine and tadalafil demonstrated a tight binding to the in silico folded BmtA transporter. We, then, tested borreliacidal activity and dose response of the shortlisted compounds from this screen using a series of in vitro assays. Amongst the probed compounds, desloratadine exhibited potent borreliacidal activity in vitro at and above 78 μg/mL (250 μM). Borrelia treated with lethal doses of desloratadine exhibited a significant loss of intracellular Mn specifically and a severe structural damage to the bacterial cell wall. Our results support the possibility of developing a novel, targeted therapy to treat Lyme disease by targeting specific metabolic needs of Borrelia.
View details for DOI 10.2147/DDDT.S77063
View details for Web of Science ID 000349239100003
View details for PubMedID 25709405
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Infrared Imaging Tools for Diagnostic Applications in Dermatology.
SM journal of clinical and medical imaging
2015; 1 (1): 1-5
Abstract
Infrared (IR) imaging is a collection of non-invasive imaging techniques that utilize the IR domain of the electromagnetic spectrum for tissue assessment. A subset of these techniques construct images using back-reflected light, while other techniques rely on detection of IR radiation emitted by the tissue as a result of its temperature. Modern IR detectors sense thermal emissions and produce a heat map of surface temperature distribution in tissues. Thus, the IR spectrum offers a variety of imaging applications particularly useful in clinical diagnostic area, ranging from high-resolution, depth-resolved visualization of tissue to temperature variation assessment. These techniques have been helpful in the diagnosis of many medical conditions including skin/breast cancer, arthritis, allergy, burns, and others. In this review, we discuss current roles of IR-imaging techniques for diagnostic applications in dermatology with an emphasis on skin cancer, allergies, blisters, burns and wounds.
View details for PubMedID 26691203
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Borreliacidal activity of Borrelia metal transporter A (BmtA) binding small molecules by manganese transport inhibition.
Drug design, development and therapy
2015; 9: 805-816
Abstract
Borrelia burgdorferi, the causative agent of Lyme disease, utilizes manganese (Mn) for its various metabolic needs. We hypothesized that blocking Mn transporter could be a possible approach to inhibit metabolic activity of this pathogen and eliminate the infection. We used a combination of in silico protein structure prediction together with molecular docking to target the Borrelia metal transporter A (BmtA), a single known Mn transporter in Borrelia and screened libraries of FDA approved compounds that could potentially bind to the predicted BmtA structure with high affinity. Tricyclic antihistamines such as loratadine, desloratadine, and 3-hydroxydesloratadine as well as yohimbine and tadalafil demonstrated a tight binding to the in silico folded BmtA transporter. We, then, tested borreliacidal activity and dose response of the shortlisted compounds from this screen using a series of in vitro assays. Amongst the probed compounds, desloratadine exhibited potent borreliacidal activity in vitro at and above 78 μg/mL (250 μM). Borrelia treated with lethal doses of desloratadine exhibited a significant loss of intracellular Mn specifically and a severe structural damage to the bacterial cell wall. Our results support the possibility of developing a novel, targeted therapy to treat Lyme disease by targeting specific metabolic needs of Borrelia.
View details for DOI 10.2147/DDDT.S77063
View details for PubMedID 25709405
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Anti-hyperlipidemic actions of synthetic nordihydroguaiaretic acid analogs
FEDERATION AMER SOC EXP BIOL. 2014
View details for Web of Science ID 000346646704181
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Polymeric Nanoparticles to Combat Squamous Cell Carcinomas in Patients with Dystrophic Epidermolysis Bullosa.
Recent patents on nanomedicine
2014; 4 (1): 15-24
Abstract
Skin cancer is the leading cause of malignancy in the United States, with Basal Cell Carcinoma, Squamous Cell Carcinoma , and Melanoma being the three most common diagnoses, respectively. Squamous Cell Carcinoma (SCC) is a particular concern for patients suffering from Dystrophic Epidermolysis Bullosa (DEB), a disease that affects the production and function of collagen VII, a protein that forms the anchoring fibrils which bind the epidermis to the dermis. Patients with DEB suffer from chronic blistering and wounds that have impaired healing capabilities, often leading to the development of SCC and eventual mortality. Nanomedicine is playing an increasing role in the delivery of effective therapeutics to combat a wide range of diseases, including the imaging and treatment of SCC. In this review, we discuss the role of nanoparticles in the treatment of SCC with an emphasis on PLGA nanoparticles and SCCs found in patients suffering from DEB, and address recent patents that are pertinent to the development of novel nanomedical therapeutics.
View details for PubMedID 25506404
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Solvent Microenvironments and Copper Binding Alters the Conformation and Toxicity of a Prion Fragment
PLOS ONE
2013; 8 (12)
Abstract
The secondary structures of amyloidogenic proteins are largely influenced by various intra and extra cellular microenvironments and metal ions that govern cytotoxicity. The secondary structure of a prion fragment, PrP(111-126), was determined using circular dichroism (CD) spectroscopy in various microenvironments. The conformational preferences of the prion peptide fragment were examined by changing solvent conditions and pH, and by introducing external stress (sonication). These physical and chemical environments simulate various cellular components at the water-membrane interface, namely differing aqueous environments and metal chelating ions. The results show that PrP(111-126) adopts different conformations in assembled and non-assembled forms. Aging studies on the PrP(111-126) peptide fragment in aqueous buffer demonstrated a structural transition from random coil to a stable β-sheet structure. A similar, but significantly accelerated structural transition was observed upon sonication in aqueous environment. With increasing TFE concentrations, the helical content of PrP(111-126) increased persistently during the structural transition process from random coil. In aqueous SDS solution, PrP(111-126) exhibited β-sheet conformation with greater α-helical content. No significant conformational changes were observed under various pH conditions. Addition of Cu(2+) ions inhibited the structural transition and fibril formation of the peptide in a cell free in vitro system. The fact that Cu(2+) supplementation attenuates the fibrillar assemblies and cytotoxicity of PrP(111-126) was witnessed through structural morphology studies using AFM as well as cytotoxicity using MTT measurements. We observed negligible effects during both physical and chemical stimulation on conformation of the prion fragment in the presence of Cu(2+) ions. The toxicity of PrP(111-126) to cultured astrocytes was reduced following the addition of Cu(2+) ions, owing to binding affinity of copper towards histidine moiety present in the peptide.
View details for DOI 10.1371/journal.pone.0085160
View details for Web of Science ID 000329117900128
View details for PubMedID 24386462
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Blocking macrophage leukotriene b4 prevents endothelial injury and reverses pulmonary hypertension.
Science translational medicine
2013; 5 (200): 200ra117-?
Abstract
Pulmonary hypertension (PH) is a serious condition that affects mainly young and middle-aged women, and its etiology is poorly understood. A prominent pathological feature of PH is accumulation of macrophages near the arterioles of the lung. In both clinical tissue and the SU5416 (SU)/athymic rat model of severe PH, we found that the accumulated macrophages expressed high levels of leukotriene A4 hydrolase (LTA4H), the biosynthetic enzyme for leukotriene B4 (LTB4). Moreover, macrophage-derived LTB4 directly induced apoptosis in pulmonary artery endothelial cells (PAECs). Further, LTB4 induced proliferation and hypertrophy of human pulmonary artery smooth muscle cells. We found that LTB4 acted through its receptor, BLT1, to induce PAEC apoptosis by inhibiting the protective endothelial sphingosine kinase 1 (Sphk1)-endothelial nitric oxide synthase (eNOS) pathway. Blocking LTA4H decreased in vivo LTB4 levels, prevented PAEC apoptosis, restored Sphk1-eNOS signaling, and reversed fulminant PH in the SU/athymic rat model of PH. Antagonizing BLT1 similarly reversed established PH. Inhibition of LTB4 biosynthesis or signal transduction in SU-treated athymic rats with established disease also improved cardiac function and reopened obstructed arterioles; this approach was also effective in the monocrotaline model of severe PH. Human plexiform lesions, one hallmark of PH, showed increased numbers of macrophages, which expressed LTA4H, and patients with connective tissue disease-associated pulmonary arterial hypertension exhibited significantly higher LTB4 concentrations in the systemic circulation than did healthy subjects. These results uncover a possible role for macrophage-derived LTB4 in PH pathogenesis and identify a pathway that may be amenable to therapeutic targeting.
View details for DOI 10.1126/scitranslmed.3006674
View details for PubMedID 23986401
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Blocking Macrophage Leukotriene B-4 Prevents Endothelial Injury and Reverses Pulmonary Hypertension
SCIENCE TRANSLATIONAL MEDICINE
2013; 5 (200)
Abstract
Pulmonary hypertension (PH) is a serious condition that affects mainly young and middle-aged women, and its etiology is poorly understood. A prominent pathological feature of PH is accumulation of macrophages near the arterioles of the lung. In both clinical tissue and the SU5416 (SU)/athymic rat model of severe PH, we found that the accumulated macrophages expressed high levels of leukotriene A4 hydrolase (LTA4H), the biosynthetic enzyme for leukotriene B4 (LTB4). Moreover, macrophage-derived LTB4 directly induced apoptosis in pulmonary artery endothelial cells (PAECs). Further, LTB4 induced proliferation and hypertrophy of human pulmonary artery smooth muscle cells. We found that LTB4 acted through its receptor, BLT1, to induce PAEC apoptosis by inhibiting the protective endothelial sphingosine kinase 1 (Sphk1)-endothelial nitric oxide synthase (eNOS) pathway. Blocking LTA4H decreased in vivo LTB4 levels, prevented PAEC apoptosis, restored Sphk1-eNOS signaling, and reversed fulminant PH in the SU/athymic rat model of PH. Antagonizing BLT1 similarly reversed established PH. Inhibition of LTB4 biosynthesis or signal transduction in SU-treated athymic rats with established disease also improved cardiac function and reopened obstructed arterioles; this approach was also effective in the monocrotaline model of severe PH. Human plexiform lesions, one hallmark of PH, showed increased numbers of macrophages, which expressed LTA4H, and patients with connective tissue disease-associated pulmonary arterial hypertension exhibited significantly higher LTB4 concentrations in the systemic circulation than did healthy subjects. These results uncover a possible role for macrophage-derived LTB4 in PH pathogenesis and identify a pathway that may be amenable to therapeutic targeting.
View details for Web of Science ID 000323705100010
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Polyvinylpyrrolidone microneedles enable delivery of intact proteins for diagnostic and therapeutic applications
ACTA BIOMATERIALIA
2013; 9 (8): 7767-7774
Abstract
We present a method of fabricating microneedles from polyvinylpyrrolidone (PVP) that enables delivery of intact proteins (or peptides) to the dermal layers of the skin. PVP is known to self-assemble into branched hollow fibers in aqueous and alcoholic solutions; we utilized this property to develop dissolvable patches of microneedles. Proteins were dissolved in concentrated PVP solution in both alcohol and water, poured into polydimethylsiloxane templates shaped as microneedles and, upon evaporation of solvent, formed into concentric, fibrous, layered structures. This approach of making PVP microneedles overcomes problems in dosage, uniform delivery and stability of protein formulation as compared to protein-coated metallic microneedles or photopolymerized PVP microneedles. Here we characterize the PVP microneedles and measure the delivery of proteins into skin. We show that our method of fabrication preserves the protein conformation. These microneedles can serve as a broadly useful platform for delivering protein antigens and therapeutic proteins to the skin, for example for allergen skin testing or immunotherapy.
View details for DOI 10.1016/j.actbio.2013.04.045
View details for PubMedID 23648574
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Enhanced A beta(1-40) Production in Endothelial Cells Stimulated with Fibrillar A beta(1-42)
PLOS ONE
2013; 8 (3)
Abstract
Amyloid accumulation in the brain of Alzheimer's patients results from altered processing of the 39- to 43-amino acid amyloid β protein (Aβ). The mechanisms for the elevated amyloid (Aβ(1-42)) are considered to be over-expression of the amyloid precursor protein (APP), enhanced cleavage of APP to Aβ, and decreased clearance of Aβ from the central nervous system (CNS). We report herein studies of Aβ stimulated effects on endothelial cells. We observe an interesting and as yet unprecedented feedback effect involving Aβ(1-42) fibril-induced synthesis of APP by Western blot analysis in the endothelial cell line Hep-1. We further observe an increase in the expression of Aβ(1-40) by flow cytometry and fluorescence microscopy. This phenomenon is reproducible for cultures grown both in the presence and absence of serum. In the former case, flow cytometry reveals that Aβ(1-40) accumulation is less pronounced than under serum-free conditions. Immunofluorescence staining further corroborates these observations. Cellular responses to fibrillar Aβ(1-42) treatment involving eNOS upregulation and increased autophagy are also reported.
View details for DOI 10.1371/journal.pone.0058194
View details for Web of Science ID 000318334500058
View details for PubMedCentralID PMC3591408
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Enhanced Aß(1-40) production in endothelial cells stimulated with fibrillar Aß(1-42).
PloS one
2013; 8 (3)
Abstract
Amyloid accumulation in the brain of Alzheimer's patients results from altered processing of the 39- to 43-amino acid amyloid β protein (Aβ). The mechanisms for the elevated amyloid (Aβ(1-42)) are considered to be over-expression of the amyloid precursor protein (APP), enhanced cleavage of APP to Aβ, and decreased clearance of Aβ from the central nervous system (CNS). We report herein studies of Aβ stimulated effects on endothelial cells. We observe an interesting and as yet unprecedented feedback effect involving Aβ(1-42) fibril-induced synthesis of APP by Western blot analysis in the endothelial cell line Hep-1. We further observe an increase in the expression of Aβ(1-40) by flow cytometry and fluorescence microscopy. This phenomenon is reproducible for cultures grown both in the presence and absence of serum. In the former case, flow cytometry reveals that Aβ(1-40) accumulation is less pronounced than under serum-free conditions. Immunofluorescence staining further corroborates these observations. Cellular responses to fibrillar Aβ(1-42) treatment involving eNOS upregulation and increased autophagy are also reported.
View details for DOI 10.1371/journal.pone.0058194
View details for PubMedID 23505467
View details for PubMedCentralID PMC3591408
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Solvent microenvironments and copper binding alters the conformation and toxicity of a prion fragment.
PloS one
2013; 8 (12)
Abstract
The secondary structures of amyloidogenic proteins are largely influenced by various intra and extra cellular microenvironments and metal ions that govern cytotoxicity. The secondary structure of a prion fragment, PrP(111-126), was determined using circular dichroism (CD) spectroscopy in various microenvironments. The conformational preferences of the prion peptide fragment were examined by changing solvent conditions and pH, and by introducing external stress (sonication). These physical and chemical environments simulate various cellular components at the water-membrane interface, namely differing aqueous environments and metal chelating ions. The results show that PrP(111-126) adopts different conformations in assembled and non-assembled forms. Aging studies on the PrP(111-126) peptide fragment in aqueous buffer demonstrated a structural transition from random coil to a stable β-sheet structure. A similar, but significantly accelerated structural transition was observed upon sonication in aqueous environment. With increasing TFE concentrations, the helical content of PrP(111-126) increased persistently during the structural transition process from random coil. In aqueous SDS solution, PrP(111-126) exhibited β-sheet conformation with greater α-helical content. No significant conformational changes were observed under various pH conditions. Addition of Cu(2+) ions inhibited the structural transition and fibril formation of the peptide in a cell free in vitro system. The fact that Cu(2+) supplementation attenuates the fibrillar assemblies and cytotoxicity of PrP(111-126) was witnessed through structural morphology studies using AFM as well as cytotoxicity using MTT measurements. We observed negligible effects during both physical and chemical stimulation on conformation of the prion fragment in the presence of Cu(2+) ions. The toxicity of PrP(111-126) to cultured astrocytes was reduced following the addition of Cu(2+) ions, owing to binding affinity of copper towards histidine moiety present in the peptide.
View details for DOI 10.1371/journal.pone.0085160
View details for PubMedID 24386462
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Glucose Oxidase Incorporated Collagen Matrices for Dermal Wound Repair in Diabetic Rat Models: A Biochemical Study
JOURNAL OF BIOMATERIALS APPLICATIONS
2012; 26 (8): 917-938
Abstract
Impaired wound healing in diabetes is a well-documented phenomenon. Emerging data favor the involvement of free radicals in the pathogenesis of diabetic wound healing. We investigated the beneficial role of the sustained release of reactive oxygen species (ROS) in diabetic dermal wound healing. In order to achieve the sustained delivery of ROS in the wound bed, we have incorporated glucose oxidase in the collagen matrix (GOIC), which is applied to the healing diabetic wound. Our in vitro proteolysis studies on incorporated GOIC show increased stability against the proteases in the collagen matrix. In this study, GOIC film and collagen film (CF) are used as dressing material on the wound of streptozotocin-induced diabetic rats. A significant increase in ROS (p < 0.05) was observed in the fibroblast of GOIC group during the inflammation period compared to the CF and control groups. This elevated level up regulated the antioxidant status in the granulation tissue and improved cellular proliferation in the GOIC group. Interestingly, our biochemical parameters nitric oxide, hydroxyproline, uronic acid, protein, and DNA content in the healing wound showed that there is an increase in proliferation of cells in GOIC when compared to the control and CF groups. In addition, evidence from wound contraction and histology reveals faster healing in the GOIC group. Our observations document that GOIC matrices could be effectively used for diabetic wound healing therapy.
View details for DOI 10.1177/0885328210390402
View details for Web of Science ID 000303649700002
View details for PubMedID 21363874
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Pullulan Hydrogels Improve Mesenchymal Stem Cell Delivery into High-Oxidative-Stress Wounds
MACROMOLECULAR BIOSCIENCE
2011; 11 (11): 1458-1466
Abstract
Cell-based therapies for wound repair are limited by inefficient delivery systems that fail to protect cells from the acute inflammatory environment. Here, a biomimetic hydrogel system is described that is based on the polymer pullulan, a carbohydrate glucan known to exhibit potent antioxidant capabilities. It is shown that pullulan hydrogels are an effective cell delivery system and improve mesenchymal stem cell survival and engraftment in high-oxidative-stress environments. The results suggest that glucan hydrogel systems may prove beneficial for progenitor-cell-based approaches to skin regeneration.
View details for DOI 10.1002/mabi.201100180
View details for Web of Science ID 000297555500002
View details for PubMedID 21994074
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Structural dynamics of the Delta E22 (Osaka) familial Alzheimer's disease-linked amyloid beta-protein
AMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS
2011; 18 (3): 98-107
Abstract
A familial form of Alzheimer disease recently was described in a kindred in Osaka, Japan. This kindred possesses an amyloid β-protein (Aβ) precursor mutation within the Aβ coding region that results in the deletion of Glu22 (ΔE22). We report here results of studies of [ΔE22]Aβ40 and [ΔE22]Aβ42 that sought to elucidate the conformational dynamics, oligomerization behavior, fibril formation kinetics, fibril morphology, and fibril stability of these mutant peptides. Both [ΔE22]Aβ peptides had extraordinary β-sheet formation propensities. The [ΔE22]Aβ40 mutant formed β-sheet secondary structure elements ≈400-fold faster. Studies of β-sheet stability in the presence of fluorinated alcohol cosolvents or high pH revealed that the ΔE22 mutation substantially increased stability, producing a rank order of [ΔE22]Aβ42 >Aβ42 > [ΔE22]Aβ40 > Aβ40. The mutation facilitated formation of oligomers by [ΔE22]Aβ42 (dodecamers and octadecamers) that were not observed with Aβ42. Both Aβ40 and Aβ42 peptides formed nebulous globular and small string-like structures immediately upon solvation from lyophilizates, whereas short protofibrillar and fibrillar structures were evident immediately in the ΔE22 samples. Determination of the critical concentration for fibril formation for the [ΔE22]Aβ peptides showed it to be ≈1/2 that of the wild type homologues, demonstrating that the mutations causes a modest increase in fibril stability. The magnitude of this increase, when considered in the context of the extraordinary increase in β-sheet propensity for the ΔE22 peptides, suggests that the primary biophysical effect of the mutation is to accelerate conformational changes in the peptide monomer that facilitate oligomerization and higher-order assembly.
View details for DOI 10.3109/13506129.2011.580399
View details for Web of Science ID 000294117300003
View details for PubMedID 21668291
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Rationally Designed Turn Promoting Mutation in the Amyloid-beta Peptide Sequence Stabilizes Oligomers in Solution
PLOS ONE
2011; 6 (7)
Abstract
Enhanced production of a 42-residue beta amyloid peptide (Aβ(42)) in affected parts of the brain has been suggested to be the main causative factor for the development of Alzheimer's Disease (AD). The severity of the disease depends not only on the amount of the peptide but also its conformational transition leading to the formation of oligomeric amyloid-derived diffusible ligands (ADDLs) in the brain of AD patients. Despite being significant to the understanding of AD mechanism, no atomic-resolution structures are available for these species due to the evanescent nature of ADDLs that hinders most structural biophysical investigations. Based on our molecular modeling and computational studies, we have designed Met35Nle and G37p mutations in the Aβ(42) peptide (Aβ(42)Nle35p37) that appear to organize Aβ(42) into stable oligomers. 2D NMR on the Aβ(42)Nle35p37 peptide revealed the occurrence of two β-turns in the V24-N27 and V36-V39 stretches that could be the possible cause for the oligomer stability. We did not observe corresponding NOEs for the V24-N27 turn in the Aβ(21-43)Nle35p37 fragment suggesting the need for the longer length amyloid peptide to form the stable oligomer promoting conformation. Because of the presence of two turns in the mutant peptide which were absent in solid state NMR structures for the fibrils, we propose, fibril formation might be hindered. The biophysical information obtained in this work could aid in the development of structural models for toxic oligomer formation that could facilitate the development of therapeutic approaches to AD.
View details for DOI 10.1371/journal.pone.0021776
View details for Web of Science ID 000293097300006
View details for PubMedID 21799748
View details for PubMedCentralID PMC3142112
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Efficient gene delivery of primary human cells using peptide linked polyethylenimine polymer hybrid
BIOMATERIALS
2011; 32 (20): 4647-4658
Abstract
Polyethylenimine (PEI) based polymers are efficient agents for cell transfection. However, their use has been hampered due to high cell death associated with transfection thereby resulting in low efficiency of gene delivery within the cells. To circumvent the problem of cellular toxicity, metal binding peptides were linked to PEI. Eight peptide-PEI derivatives were synthesized to improve cell survival and transfection efficiency. TAT linked PEI was used as a control polymer. Peptides linked with PEI amines formed nanogels as shown by electron microscopy and atomic force microscopic measurements. Polymers were characterized by spectroscopic methods and their ability to form complexes with plasmids was tested using electrophoretic studies. These modifications improved polymer biocompatibility as well as cell survival markedly, when compared to PEI alone. A subset of the modified peptide-polymers also showed significantly higher transfection efficiency in primary human cells with respect to the widely used transfection agent, lipofectamine. Study of the underlying mechanism of the observed phenomena revealed lower levels of 'reactive oxygen species' (ROS) in the presence of the peptide-polymers when compared to PEI alone. This was further corroborated with global gene expression analysis which showed upregulation of multiple genes and pathways involved in regulating intracellular oxidative stress.
View details for DOI 10.1016/j.biomaterials.2011.03.016
View details for Web of Science ID 000291193700019
View details for PubMedID 21477858
View details for PubMedCentralID PMC3090516
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Amino Acid Position-specific Contributions to Amyloid beta-Protein Oligomerization
JOURNAL OF BIOLOGICAL CHEMISTRY
2009; 284 (35): 23580-23591
Abstract
Understanding the structural and assembly dynamics of the amyloid beta-protein (Abeta) has direct relevance to the development of therapeutic agents for Alzheimer disease. To elucidate these dynamics, we combined scanning amino acid substitution with a method for quantitative determination of the Abeta oligomer frequency distribution, photo-induced cross-linking of unmodified proteins (PICUP), to perform "scanning PICUP." Tyr, a reactive group in PICUP, was substituted at position 1, 10, 20, 30, or 40 (for Abeta40) or 42 (for Abeta42). The effects of these substitutions were probed using circular dichroism spectroscopy, thioflavin T binding, electron microscopy, PICUP, and mass spectrometry. All peptides displayed a random coil --> alpha/beta --> beta transition, but substitution-dependent alterations in assembly kinetics and conformer complexity were observed. Tyr(1)-substituted homologues of Abeta40 and Abeta42 assembled the slowest and yielded unusual patterns of oligomer bands in gel electrophoresis experiments, suggesting oligomer compaction had occurred. Consistent with this suggestion was the observation of relatively narrow [Tyr(1)]Abeta40 fibrils. Substitution of Abeta40 at the C terminus decreased the population conformational complexity and substantially extended the highest order of oligomers observed. This latter effect was observed in both Abeta40 and Abeta42 as the Tyr substitution position number increased. The ability of a single substitution (Tyr(1)) to alter Abeta assembly kinetics and the oligomer frequency distribution suggests that the N terminus is not a benign peptide segment, but rather that Abeta conformational dynamics and assembly are affected significantly by the competition between the N and C termini to form a stable complex with the central hydrophobic cluster.
View details for DOI 10.1074/jbc.M109.038133
View details for Web of Science ID 000269180000044
View details for PubMedID 19567875
View details for PubMedCentralID PMC2749133
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Synthesis, pharmacological screening, quantum chemical and in vitro permeability studies of N-Mannich bases of benzimidazoles through bovine cornea
EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY
2009; 44 (5): 2307-2312
Abstract
A novel series of N-Mannich bases of benzimidazole derivatives were synthesized and characterized by (1)H NMR, IR spectral studies and elemental analysis. The compounds were screened for analgesic and anti-inflammatory activity. 1-((Diethylamino)-methyl)-2-styryl benzimidazole 4 at 40mg/kg was found to be equipotent to paracetamol. 1-((Piperidin-1-yl) methyl)-2-styryl-benzimidazole 6 at 40mg/kg was found to be more potent than Diclofenac. Corneal permeability and quantum chemical calculations were performed to correlate the hydrogen bonding ability with permeability and activity. The energies of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were correlated with pharmacological activity. The semi-empirical PM3 calculations (quantum chemical calculations) revealed that E(LUMO) and energy gap DeltaE were capable of accounting for the high in vitro bovine corneal permeability and activity of the compounds.
View details for DOI 10.1016/j.ejmech.2008.03.043
View details for Web of Science ID 000265339900062
View details for PubMedID 18486995
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Conformational polymorphism and cellular toxicity of IAPP and beta AP domains
JOURNAL OF STRUCTURAL BIOLOGY
2009; 166 (2): 116-125
Abstract
The principal component of the amyloid deposits in Alzheimer's disease is the beta-amyloid polypeptide, while in type II diabetes the deposits consist primarily of Islet amyloid polypeptide. These amyloid forming polypeptides consist of highly polymorphic domains, which take different conformations including random coil, helical and beta strand depending upon the microenvironment. We have studied major fibril-forming components of IAPP and beta AP and demonstrated that conformational polymorphism of these peptides in different microenvironments correlate with cellular toxicity and proteasomal inhibitory activity. On treating with trifluoroethanol (TFE) the peptide fragments undergo structural transition from a random coil to a helical conformation. Even though these domains share the same gross amyloid structural characteristic, their proteasomal activities differ. We found that even the tetrapeptides have significant proteasomal inhibitory activity indicating that the amyloid formation is involved in the enhanced life of the smaller aggregates of full-length and fragment peptides, which could explain the toxicity of these sequences.
View details for DOI 10.1016/j.jsb.2008.12.011
View details for Web of Science ID 000265560900002
View details for PubMedID 19374013
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Alzheimer disease macrophages shuttle amyloid-beta from neurons to vessels, contributing to amyloid angiopathy
ACTA NEUROPATHOLOGICA
2009; 117 (2): 111-124
Abstract
Neuronal accumulation of oligomeric amyloid-beta (Alphabeta) is considered the proximal cause of neuronal demise in Alzheimer disease (AD) patients. Blood-borne macrophages might reduce Abeta stress to neurons by immigration into the brain and phagocytosis of Alphabeta. We tested migration and export across a blood-brain barrier model, and phagocytosis and clearance of Alphabeta by AD and normal subjects' macrophages. Both AD and normal macrophages were inhibited in Alphabeta export across the blood-brain barrier due to adherence of Abeta-engorged macrophages to the endothelial layer. In comparison to normal subjects' macrophages, AD macrophages ingested and cleared less Alphabeta, and underwent apoptosis upon exposure to soluble, protofibrillar, or fibrillar Alphabeta. Confocal microscopy of stained AD brain sections revealed oligomeric Abeta in neurons and apoptotic macrophages, which surrounded and infiltrated congophilic microvessels, and fibrillar Abeta in plaques and microvessel walls. After incubation with AD brain sections, normal subjects' monocytes intruded into neurons and uploaded oligomeric Abeta. In conclusion, in patients with AD, macrophages appear to shuttle Abeta from neurons to vessels where their apoptosis may release fibrillar Abeta, contributing to cerebral amyloid angiopathy.
View details for DOI 10.1007/s00401-008-0481-0
View details for Web of Science ID 000262784500002
View details for PubMedID 19139910
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Amyloid beta-Protein Assembly as a Therapeutic Target of Alzheimer's Disease
CURRENT PHARMACEUTICAL DESIGN
2008; 14 (30): 3231-3246
Abstract
Alzheimer's disease (AD), the most common neurodegenerative disorder in the aged, is characterized by the cerebral deposition of fibrils formed by the amyloid beta-protein (Abeta), a 40-42 amino acid peptide. The folding of Abeta into neurotoxic oligomeric, protofibrillar, and fibrillar assemblies is hypothesized to be the key pathologic event in AD. Abeta is formed through cleavage of the Abeta precursor protein by two endoproteinases, beta-secretase and gamma-secretase, that cleave the Abeta N-terminus and C-terminus, respectively. These facts support the relevance of therapeutic strategies targeting Abeta production, assembly, clearance, and neurotoxicity. Currently, no disease-modifying therapeutic agents are available for AD patients. Instead, existing therapeutics provide only modest symptomatic benefits for a limited time. We summarize here recent efforts to produce therapeutic drugs targeting Abeta assembly. A number of approaches are being used in these efforts, including immunological, nutraceutical, and more classical medicinal chemical (peptidic inhibitors, carbohydrate-containing compounds, polyamines, "drug-like" compounds, chaperones, metal chelators, and osmolytes), and many of these have progressed to phase III clinical trails. We also discuss briefly a number of less mature, but intriguing, strategies that have therapeutic potential. Although initial trials of some disease-modifying agents have failed, we argue that substantial cause for optimism exists.
View details for Web of Science ID 000261916000004
View details for PubMedID 19075703
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Isolation and partial characterization of antifungal protein from Bacillus polymyxa strain VLB16
PROCESS BIOCHEMISTRY
2005; 40 (10): 3236-3243
View details for DOI 10.1016/j.procbio.2005.03.060
View details for Web of Science ID 000231833100014
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Effect of osmolyte on the micellization of SDS at different temperatures
LANGMUIR
2003; 19 (22): 9545-9547
View details for DOI 10.1021/la034403z
View details for Web of Science ID 000186177200068
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Effect of Ca2+ on the self assembly of a nonionic peptide aggregate
LETTERS IN PEPTIDE SCIENCE
2003; 10 (1): 25-32
View details for Web of Science ID 000188666700004