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author:("Garg, nyha")
1.  Mass spectral similarity for untargeted metabolomics data analysis of complex mixtures 
While in nucleotide sequencing, the analysis of DNA from complex mixtures of organisms is common, this is not yet true for mass spectrometric data analysis of complex mixtures. The comparative analyses of mass spectrometry data of microbial communities at the molecular level is difficult to perform, especially in the context of a host. The challenge does not lie in generating the mass spectrometry data, rather much of the difficulty falls in the realm of how to derive relevant information from this data. The informatics based techniques to visualize and organize datasets are well established for metagenome sequencing; however, due to the scarcity of informatics strategies in mass spectrometry, it is currently difficult to cross correlate two very different mass spectrometry data sets from microbial communities and their hosts. We highlight that molecular networking can be used as an organizational tool of tandem mass spectrometry data, automated database search for rapid identification of metabolites, and as a workflow to manage and compare mass spectrometry data from complex mixtures of organisms. To demonstrate this platform, we show data analysis from hard corals and a human lung associated with cystic fibrosis.
PMCID: PMC4379709  PMID: 25844058
Molecular networking; mass spectrometry; complex mixtures; spectral matching; Cytoscape; database search
2.  Chemoenzymatic synthesis of acyl coenzyme A substrates enables in situ labeling of small molecules and proteins 
Organic letters  2015;17(18):4452-4455.
A chemoenzymatic approach to generate fully functional acyl coenzyme A molecules that are then used as substrates to drive in situ acyl transfer reactions is described. Mass spectrometry-based assays to verify the identity of acyl coenzyme A enzymatic products are also illustrated. The approach is responsive to a diverse array of carboxylic acids that can be elaborated to their corresponding coenzyme A thioesters, with potential applications in wide-ranging chemical biology studies that utilize acyl coenzyme A substrates.
Graphical abstract
PMCID: PMC4720141  PMID: 26333306
3.  MicroRNAs-Proteomic Networks Characterizing Human Medulloblastoma-SLCs 
Stem Cells International  2016;2016:2683042.
Medulloblastoma (MB) is the most common malignant brain tumor of pediatric age and is characterized by cells expressing stem, astroglial, and neuronal markers. Among them, stem-like cells (hMB-SLCs) represent a fraction of the tumor cell population with the potential of self-renewal and proliferation and have been associated with tumor poor prognosis. In this context, microRNAs have been described as playing a pivotal role in stem cells differentiation. In our paper, we analyze microRNAs profile and genes expression of hMB-SLCs before and after Retinoic Acid- (RA-) induced differentiation. We aimed to identify pivotal players of specific pathways sustaining stemness and/or tumor development and progression and integrate the results of our recent proteomic study. Our results uncovered 22 differentially expressed microRNAs that were used as input together with deregulated genes and proteins in the Genomatix Pathway System (GePS) analysis revealing 3 subnetworks that could be interestingly involved in the maintenance of hMB-SLCs proliferation. Taken together, our findings highlight microRNAs, genes, and proteins that are significantly modulated in hMB-SLCs with respect to their RA-differentiated counterparts and could open new perspectives for prognostic and therapeutic intervention on MB.
PMCID: PMC4736593  PMID: 26880947
4.  STAT3 pathway regulates lung-derived brain metastasis initiating cell capacity through miR-21 activation 
Oncotarget  2015;6(29):27461-27477.
Brain metastases (BM) represent the most common tumor to affect the adult central nervous system. Despite the increasing incidence of BM, likely due to consistently improving treatment of primary cancers, BM remain severely understudied. In this study, we utilized patient-derived stem cell lines from lung-to-brain metastases to examine the regulatory role of STAT3 in brain metastasis initiating cells (BMICs). Annotation of our previously described BMIC regulatory genes with protein-protein interaction network mapping identified STAT3 as a novel protein interactor. STAT3 knockdown showed a reduction in BMIC self-renewal and migration, and decreased tumor size in vivo. Screening of BMIC lines with a library of STAT3 inhibitors identified one inhibitor to significantly reduce tumor formation. Meta-analysis identified the oncomir microRNA-21 (miR-21) as a target of STAT3 activity. Inhibition of miR-21 displayed similar reductions in BMIC self-renewal and migration as STAT3 knockdown. Knockdown of STAT3 also reduced expression of known downstream targets of miR-21. Our studies have thus identified STAT3 and miR-21 as cooperative regulators of stemness, migration and tumor initiation in lung-derived BM. Therefore, STAT3 represents a potential therapeutic target in the treatment of lung-to-brain metastases.
PMCID: PMC4695002  PMID: 26314961
brain metastases; brain metastasis initiating cell; STAT3; miR-21
5.  Pluripotency Transcription Factor Oct4 Mediates Stepwise Nucleosome Demethylation and Depletion 
Molecular and Cellular Biology  2015;35(6):1014-1025.
The mechanisms whereby the crucial pluripotency transcription factor Oct4 regulates target gene expression are incompletely understood. Using an assay system based on partially differentiated embryonic stem cells, we show that Oct4 opposes the accumulation of local H3K9me2 and subsequent Dnmt3a-mediated DNA methylation. Upon binding DNA, Oct4 recruits the histone lysine demethylase Jmjd1c. Chromatin immunoprecipitation (ChIP) time course experiments identify a stepwise Oct4 mechanism involving Jmjd1c recruitment and H3K9me2 demethylation, transient FACT (facilitates chromatin transactions) complex recruitment, and nucleosome depletion. Genome-wide and targeted ChIP confirms binding of newly synthesized Oct4, together with Jmjd1c and FACT, to the Pou5f1 enhancer and a small number of other Oct4 targets, including the Nanog promoter. Histone demethylation is required for both FACT recruitment and H3 depletion. Jmjd1c is required to induce endogenous Oct4 expression and fully reprogram fibroblasts to pluripotency, indicating that the assay system identifies functional Oct4 cofactors. These findings indicate that Oct4 sequentially recruits activities that catalyze histone demethylation and depletion.
PMCID: PMC4333097  PMID: 25582194
Neuro-Oncology  2014;16(Suppl 3):iii5.
BACKGROUND: Brain tumors represent the leading cause of childhood cancer mortality, of which medulloblastoma (MB) is the most frequent malignant pediatric brain tumor. Recent studies have demonstrated the presence of several MB molecular subgroups, each distinct in terms of prognosis and predicted therapeutic response. Although, group 2 MBs characterized by activation of the sonic hedgehog (Shh) signaling pathway have been of particular therapeutic interest, treatment-resistance has posed a significant challenge. Given the identification of brain tumor-initiating cells (BTICs), which have the ability to initiate and maintain tumor growth while promoting resistance to radio- and chemotherapy, we investigated the mechanistic profile of treatment-resistant Shh-dependent MB BTICs. METHODS: Through investigating a differential stem cell gene expression profile of 325 primary human MBs, followed by a subsequent series of step-wise knockdown, overexpression, chromatin immunoprecipitation (ChIP), and in vitro self-renewal analyses we assessed the mechanistic role of Sox2 as a novel downstream target of Shh effector proteins, Gli1 and Gli2. We further determined the clinical utility of this mechanism by treating our MB BTICs with conventional radio- and chemotherapy as per the Children's Oncology Group (COG) protocol for MB patients in order to assess the validity of Sox2 as a marker of Shh-dependent treatment-refractory MB BTICs. RESULTS: Activation and inhibition of the Shh pathway and Sox2 expression using small molecule Shh agonists and antagonists, respectively, were observed only in distinct subsets of tumor cells (CD15+ MB BTICs). ChIP experiments further demonstrated the presence of a differential Shh signaling mechanism within distinct cell populations of the bulk tumor mass as Gli proteins showed Sox2 promoter binding only in CD15+ MB BTICs. The functional relevance of this cell-specific signaling mechanism was assessed through an in vitro and in vivo increase in treatment-resistant Sox2+ MB BTICs following conventional and combinatorial radio- and chemotherapy with Shh pathway inhibitors. CONCLUSIONS: Our work demonstrates for the first time that Sox2 expression in MB is regulated by the Shh signaling pathway and Sox2+ MB BTICs represent the treatment-resistant clone in Group 2 MBs, suggesting a need for combinatorial therapy as tumors evolve over the course of treatment. Aside from implicating developmental genes and pathways in oncogenesis, we have also demonstrated the importance of studying cancer at a cellular level, as distinct differences in rare subsets of tumor cells may not otherwise be appreciated with genomic profiling of the bulk tumor mass. SECONDARY CATEGORY: Neuropathology & Tumor Biomarkers.
PMCID: PMC4144480
7.  Mass spectrometry of Natural Products: Current, Emerging and Future Technologies 
Natural product reports  2014;31(6):718-729.
Although mass spectrometry is a century old technology, we are entering into an exciting time for the analysis of molecular information directly from complex biological systems. In this viewpoint article, we highlight emerging mass spectrometric methods and tools used by the natural product community and give a perspective of future directions where the mass spectrometry field is migrating towards over the next decade.
PMCID: PMC4161218  PMID: 24801551
8.  Substrate Specificity of the Lanthipeptide Peptidase ElxP and the Oxidoreductase ElxO 
ACS Chemical Biology  2014;9(8):1718-1725.
The final step in lanthipeptide biosynthesis involves the proteolytic removal of an N-terminal leader peptide. In the class I lanthipeptide epilancin 15X, this step is performed by the subtilisin-like serine peptidase ElxP. Bioinformatic, kinetic, and mass spectrometric analysis revealed that ElxP recognizes the stretch of amino acids DLNPQS located near the proteolytic cleavage site of its substrate, ElxA. When the ElxP recognition motif was inserted into the noncognate lanthipeptide precursor NisA, ElxP was able to proteolytically remove the leader peptide from NisA. Proteolytic removal of the leader peptide by ElxP during the biosynthesis of epilancin 15X exposes an N-terminal dehydroalanine on the core peptide of ElxA that hydrolyzes to a pyruvyl group. The short-chain dehydrogenase ElxO reduces the pyruvyl group to a lactyl moiety in the final step of epilancin 15X maturation. Using synthetic peptides, we also investigated the substrate specificity of ElxO and determined the 1.85 Å resolution X-ray crystal structure of the enzyme.
PMCID: PMC4136673  PMID: 24866416
9.  MicroRNA Regulation of Brain Tumour Initiating Cells in Central Nervous System Tumours 
Stem Cells International  2015;2015:141793.
CNS tumours occur in both pediatric and adult patients and many of these tumours are associated with poor clinical outcome. Due to a paradigm shift in thinking for the last several years, these tumours are now considered to originate from a small population of stem-like cells within the bulk tumour tissue. These cells, termed as brain tumour initiating cells (BTICs), are perceived to be regulated by microRNAs at the posttranscriptional/translational levels. Proliferation, stemness, differentiation, invasion, angiogenesis, metastasis, apoptosis, and cell cycle constitute some of the significant processes modulated by microRNAs in cancer initiation and progression. Characterization and functional studies on oncogenic or tumour suppressive microRNAs are made possible because of developments in sequencing and microarray techniques. In the current review, we bring recent knowledge of the role of microRNAs in BTIC formation and therapy. Special attention is paid to two highly aggressive and well-characterized brain tumours: gliomas and medulloblastoma. As microRNA seems to be altered in the pathogenesis of many human diseases, “microRNA therapy” may now have potential to improve outcomes for brain tumour patients. In this rapidly evolving field, further understanding of miRNA biology and its contribution towards cancer can be mined for new therapeutic tools.
PMCID: PMC4433683  PMID: 26064134
10.  The Intestinal Metabolome—an Intersection Between Microbiota and Host 
Gastroenterology  2014;146(6):1470-1476.
Recent advances that allow us to collect more data on DNA sequences and metabolites have increased our understanding of connections between the intestinal microbiota and metabolites, at a whole-systems level. We can also now better study the effects of specific microbes on specific metabolites. Here, we review how the microbiota determines levels of specific metabolites, how the metabolite profile develops in infants, and prospects for assessing a person’s physiological state based on their microbes and/or metabolites. Although data acquisition technologies have improved, computational challenges to integrating data from multiple levels remain formidable; developments in this area will significantly improve our ability to interpret current and future datasets.
PMCID: PMC4102302  PMID: 24631493
11.  Specialized metabolites from the microbiome in health and disease 
Cell metabolism  2014;20(5):719-730.
The microbiota, and the genes that comprise its microbiome, play key roles in human health. Host-microbe interactions affect immunity, metabolism, development, and behavior, and dysbiosis of gut bacteria contributes to disease. Despite advances in correlating changes in the microbiota with various conditions, specific mechanisms of host-microbiota signaling remain largely elusive. We discuss the synthesis of microbial metabolites, their absorption, and potential physiological effects on the host. We propose that the effects of specialized metabolites may explain present knowledge gaps linking the gut microbiota to biological host mechanisms during initial colonization, and in health and disease.
PMCID: PMC4337795  PMID: 25440054
12.  Use of surface-enhanced Raman scattering as a prognostic indicator of acute kidney transplant rejection 
Biomedical Optics Express  2015;6(3):761-769.
We report an early, noninvasive and rapid prognostic method of predicting potential acute kidney dysfunction using surface-enhanced Raman scattering (SERS). Our analysis was performed on urine samples collected prospectively from 58 kidney transplant patients using a He-Ne laser (632.8 nm) as the excitation source. All abnormal kidney function episodes (three acute rejections and two acute kidney failures that were eventually diagnosed independently by clinical biopsy) consistently exhibited unique SERS spectral features in just one day following the transplant surgery. These results suggested that SERS analysis provides an early and more specific indication to kidney function than the clinically used biomarker, serum creatinine (sCr).
PMCID: PMC4361431  PMID: 25798301
(170.5660) Raman spectroscopy; (240.6695) Surface-enhanced Raman scattering; (170.6510) Spectroscopy, tissue diagnostics; (160.4236) Nanomaterials
13.  Mode of Action and Structure-Activity Relationship Studies of Geobacillin I 
The Journal of antibiotics  2013;67(1):133-136.
PMCID: PMC4004768  PMID: 24169799
lanthionine; lantibiotics/membrane disruption; mode of action; nisin; lipid II
14.  Neuronal nitric oxide synthase is phosphorylated in response to insulin stimulation in skeletal muscle 
Type 2 Diabetes (T2DM) is the seventh leading cause of death in the United States, and is quickly becoming a global pandemic. T2DM results from reduced insulin sensitivity coupled with a relative failure of insulin secretion. Reduced insulin sensitivity has been associated with reduced nitric oxide synthase (NOS) activity and impaired glucose uptake in T2DM skeletal muscle. Upon insulin stimulation, NO synthesis increases in normal adult skeletal muscle, whereas no such increase is observed in T2DM adults. Endothelial NOS is activated by phosphorylation in the C-terminal tail in response to insulin. Neuronal NOS (nNOS), the primary NOS isoform in skeletal muscle, contains a homologous phosphorylation site, raising the possibility that nNOS, too, may undergo an activating phosphorylation event upon insulin treatment. Yet it remains unknown if or how nNOS is regulated by insulin in skeletal muscle. Data shown herein indicate that nNOS is phosphorylated in response to insulin in skeletal muscle and that this phosphorylation event occurs rapidly in C2C12 myotubes, resulting in increased NO production. In vivo phosphorylation of nNOS was also observed in response to insulin in mouse skeletal muscle. These results indicate, for the first time, that nNOS is phosphorylated in skeletal muscle in response to insulin and in association with increased NO production.
PMCID: PMC3703775  PMID: 23680665
Nitric oxide synthase; Type 2 Diabetes (T2DM); insulin signaling; myotubes; skeletal muscle
16.  Chemical Rescue and Inhibition Studies to Determine the Role of Arg301 in Phosphite Dehydrogenase 
PLoS ONE  2014;9(1):e87134.
Phosphite dehydrogenase (PTDH) catalyzes the NAD+-dependent oxidation of phosphite to phosphate. This reaction requires the deprotonation of a water nucleophile for attack on phosphite. A crystal structure was recently solved that identified Arg301 as a potential base given its proximity and orientation to the substrates and a water molecule within the active site. Mutants of this residue showed its importance for efficient catalysis, with about a 100-fold loss in kcat and substantially increased Km,phosphite for the Ala mutant (R301A). The 2.35 Å resolution crystal structure of the R301A mutant with NAD+ bound shows that removal of the guanidine group renders the active site solvent exposed, suggesting the possibility of chemical rescue of activity. We show that the catalytic activity of this mutant is restored to near wild-type levels by the addition of exogenous guanidinium analogues; Brønsted analysis of the rates of chemical rescue suggests that protonation of the rescue reagent is complete in the transition state of the rate-limiting step. Kinetic isotope effects on the reaction in the presence of rescue agents show that hydride transfer remains at least partially rate-limiting, and inhibition experiments show that Ki of sulfite with R301A is ∼400-fold increased compared to the parent enzyme, similar to the increase in Km for phosphite in this mutant. The results of our experiments indicate that Arg301 plays an important role in phosphite binding as well as catalysis, but that it is not likely to act as an active site base.
PMCID: PMC3909101  PMID: 24498026
17.  High-throughput microRNA profiling of pediatric high-grade gliomas 
Neuro-Oncology  2013;16(2):228-240.
High-grade gliomas (HGGs) account for 15% of all pediatric brain tumors and are a leading cause of cancer-related mortality and morbidity. Pediatric HGGs (pHGGs) are histologically indistinguishable from their counterpart in adulthood. However, recent investigations indicate that differences occur at the molecular level, thus suggesting that the molecular path to gliomagenesis in childhood is distinct from that of adults. MicroRNAs (miRNAs) have been identified as key molecules in gene expression regulation, both in development and in cancer. miRNAs have been investigated in adult high-grade gliomas (aHGGs), but scant information is available for pHGGs.
We explored the differences in microRNAs between pHGG and aHGG, in both fresh-frozen and paraffin-embedded tissue, by high-throughput miRNA profiling. We also evaluated the biological effects of miR-17-92 cluster silencing on a pHGG cell line.
Comparison of miRNA expression patterns in formalin versus frozen specimens resulted in high correlation between both types of samples. The analysis of miRNA profiling revealed a specific microRNA pattern in pHGG with an overexpression and a proliferative role of the miR-17-92 cluster. Moreover, we highlighted a possible quenching function of miR-17-92 cluster on its target gene PTEN, together with an activation of tumorigenic signaling such as sonic hedgehog in pHGG.
Our results suggest that microRNA profiling represents a tool to distinguishing pediatric from adult HGG and that miR-17-92 cluster sustains pHGG.
PMCID: PMC3895388  PMID: 24305714
cancer; expression profiling; microRNA; pediatric gliomas
18.  microRNA-17-92 cluster is a direct Nanog target and controls neural stem cell through Trp53inp1 
The EMBO Journal  2013;32(21):2819-2832.
The transcription factor Nanog plays a critical role in the self-renewal of embryonic stem cells as well as in neural stem cells (NSCs). microRNAs (miRNAs) are also involved in stemness regulation. However, the miRNA network downstream of Nanog is still poorly understood. High-throughput screening of miRNA expression profiles in response to modulated levels of Nanog in postnatal NSCs identifies miR-17-92 cluster as a direct target of Nanog. Nanog controls miR-17-92 cluster by binding to the upstream regulatory region and maintaining high levels of transcription in NSCs, whereas Nanog/promoter association and cluster miRNAs expression are lost alongside differentiation. The two miR-17 family members of miR-17-92 cluster, namely miR-17 and miR-20a, target Trp53inp1, a downstream component of p53 pathway. To support a functional role, the presence of miR-17/20a or the loss of Trp53inp1 is required for the Nanog-induced enhancement of self-renewal of NSCs. We unveil an arm of the Nanog/p53 pathway, which regulates stemness in postnatal NSCs, wherein Nanog counteracts p53 signals through miR-17/20a-mediated repression of Trp53inp1.
microRNA-17-92 cluster is a direct Nanog target and controls neural stem cell through Trp53inp1
Direct control of the miRNA-17/92 cluster enables Nanog to restrain p53 activity and thus to maintain pluripotency in neural stem cells.
PMCID: PMC3817465  PMID: 24076654
microRNA; miR-17-92 cluster; Nanog; neural stem cells; Trp53inp1
20.  Deficiency of Insulin-Like Growth Factor-1 Receptor Confers Resistance to Oxidative Stress in C2C12 Myoblasts 
PLoS ONE  2013;8(5):e63838.
IGF-1 receptor (IGF-1R) signaling regulates cell growth, transformation and survival. Haploinsufficiency of the IGF-1R is reported to paradoxically confer resistance to oxidative stress in vivo and in cells cultured from Igf1r+/− mice. In order to determine whether IGF-1R deficiency directly confers resistance to oxidative stress in specific cell types, an siRNA-mediated approach was applied to reduce IGF-1R in C2C12 myoblasts, NIH3T3 fibroblasts and MC3T3-E1 osteoblasts. Treating the IGF-1R deficient myoblasts with H2O2 resulted in significantly higher phosphorylation of Akt as compared to cells having normal expression of IGF-1R. Similar results were obtained with UV treatment, another inducer of oxidative stress. This enhanced activation of Akt was associated with reduced level of cleaved caspase-3 and PARP. Moreover, in the IGF-1R knockdown myoblasts, phosphorylation of the Akt substrate Bad was enhanced after peroxide treatment. However, in NIH-3T3 fibroblasts and MC3T3-E1 osteoblasts, the loss of IGF-1R by siRNA directed knockdown was associated with reduced levels of phosphorylated Akt on treatment with H2O2 or UV as compared to control cells and these cells showed more apoptosis. These results suggest a novel mechanism of cell type specific differential regulation of resistance to oxidative stress induced apoptosis by reduced levels of IGF-1R.
PMCID: PMC3651254  PMID: 23675509
21.  Oral rehabilitation of a Parkinson’s patient: A case report 
Parkinson’s disease is an idiopathic disorder of the central nervous system, characterized by resting tremors, muscular rigidity, slow and decreased movements. Oral rehabilitation of these patients requires special care, especially in those cases where the patient’s socioeconomic status is not good and patient cannot come several times for fabrication of a complete denture. This clinical report presents a case of a Parkinson’s patient who was completely rehabilitated in 3 appointments using special techniques. Border molding, final impression and jaw relation procedures were done in one appointment by using a custom tray with detachable handles and occlusal rims.
PMCID: PMC3845922  PMID: 24303468
Parkinson’s disease; Tich buttons; Detachable handles and occlusal rims; Monoplane teeth
22.  Cloning, sequence analysis, expression of Cyathus bulleri laccase in Pichia pastoris and characterization of recombinant laccase 
BMC Biotechnology  2012;12:75.
Laccases are blue multi-copper oxidases and catalyze the oxidation of phenolic and non-phenolic compounds. There is considerable interest in using these enzymes for dye degradation as well as for synthesis of aromatic compounds. Laccases are produced at relatively low levels and, sometimes, as isozymes in the native fungi. The investigation of properties of individual enzymes therefore becomes difficult. The goal of this study was to over-produce a previously reported laccase from Cyathus bulleri using the well-established expression system of Pichia pastoris and examine and compare the properties of the recombinant enzyme with that of the native laccase.
In this study, complete cDNA encoding laccase (Lac) from white rot fungus Cyathus bulleri was amplified by RACE-PCR, cloned and expressed in the culture supernatant of Pichia pastoris under the control of the alcohol oxidase (AOX)1 promoter. The coding region consisted of 1,542 bp and encodes a protein of 513 amino acids with a signal peptide of 16 amino acids. The deduced amino acid sequence of the matured protein displayed high homology with laccases from Trametes versicolor and Coprinus cinereus. The sequence analysis indicated the presence of Glu 460 and Ser 113 and LEL tripeptide at the position known to influence redox potential of laccases placing this enzyme as a high redox enzyme. Addition of copper sulfate to the production medium enhanced the level of laccase by about 12-fold to a final activity of 7200 U L-1. The recombinant laccase (rLac) was purified by ~4-fold to a specific activity of ~85 U mg-1 protein. A detailed study of thermostability, chloride and solvent tolerance of the rLac indicated improvement in the first two properties when compared to the native laccase (nLac). Altered glycosylation pattern, identified by peptide mass finger printing, was proposed to contribute to altered properties of the rLac.
Laccase of C. bulleri was successfully produced extra-cellularly to a high level of 7200 U L-1 in P. pastoris under the control of the AOX1 promoter and purified by a simple three-step procedure to homogeneity. The kinetic parameters against ABTS, Guaiacol and Pyrogallol were similar with the nLac and the rLac. Tryptic finger print analysis of the nLac and the rLac indicated altered glycosylation patterns. Increased thermo-stability and salt tolerance of the rLac was attributed to this changed pattern of glycosylation.
PMCID: PMC3558336  PMID: 23092193
Cyathus bulleri; Heterologous laccase expression; Pichia pastoris; Recombinant laccase; Peptide mass fingerprinting
23.  High Fat Diet Induced Insulin Resistance and Glucose Intolerance is Gender-Specific in IGF-1R Heterozygous Mice 
Interactions between genes and environment play a critical role in the pathogenesis of Type 2 diabetes. Low birth weight, due to genetic and environmental variables affecting fetal growth, is associated with increased susceptibility to the development of type 2 diabetes and metabolic disorders in adulthood. Clinical studies have shown that polymorphisms in the Insulin-like growth factor 1 (IGF-1) gene or heterozygous mutations in IGF-1 and IGF-1 receptor (IGF-1R) genes, resulting in reduced IGF-1 action, are associated with low birth weight and post-natal growth. Mice lacking one of the IGF-1R alleles (Igf1r+/−) exhibit a 10% reduction in post-natal growth, and develop glucose intolerance and insulin resistance as they age. To investigate whether adverse environmental factors could accelerate the onset of the metabolic syndrome, we conducted a short duration intervention of high fat diet (HFD) feeding in male and female Igf1r+/− and wild-type (WT) control mice. The HFD resulted in insulin resistance, hyperglycemia, and impaired glucose tolerance in males of both genotypes whereas in females exacerbated diabetes was observed only in the Igf1r+/− genotype, thus suggesting a sexual dimorphism in the influence of obesity on the genetic predisposition to diabetes caused by reduced IGF-1 action.
PMCID: PMC3185216  PMID: 21910970
IGF-1; IGF-1R; Igf1r+/−; SGA; HFD; Type 2 diabetes
24.  Does Reduced IGF-1R Signaling in Igf1r+/− Mice Alter Aging? 
PLoS ONE  2011;6(11):e26891.
Mutations in insulin/IGF-1 signaling pathway have been shown to lead to increased longevity in various invertebrate models. Therefore, the effect of the haplo- insufficiency of the IGF-1 receptor (Igf1r+/−) on longevity/aging was evaluated in C57Bl/6 mice using rigorous criteria where lifespan and end-of-life pathology were measured under optimal husbandry conditions using large sample sizes. Igf1r+/− mice exhibited reductions in IGF-1 receptor levels and the activation of Akt by IGF-1, with no compensatory increases in serum IGF-1 or tissue IGF-1 mRNA levels, indicating that the Igf1r+/− mice show reduced IGF-1 signaling. Aged male, but not female Igf1r+/− mice were glucose intolerant, and both genders developed insulin resistance as they aged. Female, but not male Igf1r+/− mice survived longer than wild type mice after lethal paraquat and diquat exposure, and female Igf1r+/− mice also exhibited less diquat-induced liver damage. However, no significant difference between the lifespans of the male Igf1r+/− and wild type mice was observed; and the mean lifespan of the Igf1r+/− females was increased only slightly (less than 5%) compared to wild type mice. A comprehensive pathological analysis showed no significant difference in end-of-life pathological lesions between the Igf1r+/− and wild type mice. These data show that the Igf1r+/− mouse is not a model of increased longevity and delayed aging as predicted by invertebrate models with mutations in the insulin/IGF-1 signaling pathway.
PMCID: PMC3223158  PMID: 22132081
25.  Inhibition of the Growth of Plasmodium falciparum in Culture by Stearylamine-Phosphatidylcholine Liposomes 
We have examined the effect of stearylamine (SA) in liposomes on the viability of Plasmodium falciparum in culture by studying the inhibition of incorporation of [3H]-hypoxanthine in the nucleic acid of parasites. Stearylamine in liposomes significantly inhibits the growth of the parasites depending on the phospholipids composition. The maximum inhibition was observed when SA was delivered through Soya phosphatidylcholine (SPC) liposomes. The chain length of alkyl group and density of SA in liposomes play a significant role in inhibiting the growth of the parasites. Incorporation of either cholesterol or Distearylphosphatidylethanolamine−Methoxy-Polyethylene glycol-2000 (DSPE-mPEG-2000) in Soya phosphatidylcholine-stearylamine (SPC-SA) liposomes improves the efficacy. Intraerythrocytic entry of intact SPC-SA liposomes into infected erythrocytes was visualized using fluorescent microscopy. No hemolysis was observed in uninfected erythrocytes, and slight hemolysis was noted in infected erythrocytes at high concentrations of SPC-SA liposomes. Overall, our data suggested SA in SPC-liposomes might have potential application in malaria chemotherapy.
PMCID: PMC3135048  PMID: 21772979

Results 1-25 (26)