Search tips
Search criteria

Results 1-23 (23)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
author:("Singh, neet")
1.  Inhibition of Cathepsin B by E-64 Induces Oxidative Stress and Apoptosis in Filarial Parasite 
PLoS ONE  2014;9(3):e93161.
Current available antifilarial drug strategies only eliminate the larval stages of filarial parasites. Therefore, there is an urgent need of drugs which are macrofilaricidals. Identification of molecular targets crucial for survival of parasite is a prerequisite for drug designing. Cathepsin B, a cysteine protease family member is known to play crucial role in the normal growth, digestion of nutrients, exsheathment of the helminth parasites. Therefore, we targeted this enzyme in the filarial parasite using its specific inhibitor, E-64.
Methods and Findings
We have exposed the parasites to E-64 and observed their motility and viability at various time intervals. It caused marked decrease in the motility and viability of the parasites ultimately leading to their death after 8 hours. It is well known that E-64 protects the cell from apoptosis, however, it causes apoptotic effect in carcinoma cell lines. To understand the mechanism of action of E-64 on parasite survival, we have measured levels of different apoptotic markers in the treated parasites. E-64 significantly reduced the level of ced-9 and activity of tyrosine phosphatases, cytochrome c oxidase. It also activated ced-3, homolog of mammalian caspase 3 suggesting initiation of an apoptotic like event in the filarial parasites. Different antioxidant enzymes were also evaluated to further explore the mechanism behind the death of the parasites. There was marked decrease in the level of GSH and activity of Glutathione reductase and glutathione-s-transferase leading to increased generation of reactive oxygen species. This led to the induced oxidation of fatty acids and protein which might alter the mitochondrial membrane permeability.
This study suggests that inhibition of cathepsin B by E-64 generates oxidative stress followed by mitochondrial mediated apoptotic like event in filarial parasites leading to their death. Hence, suggesting filarial cathepsin B as a potential chemotherapeutic target for lymphatic filariasis.
PMCID: PMC3965533  PMID: 24667798
2.  TGF-β Mediated Crosstalk Between Malignant Hepatocyte and Tumor Microenvironment in Hepatocellular Carcinoma 
In this article, we have reviewed current literature regarding the regulation of hepatocellular carcinoma (HCC) by the interaction of malignant hepatocytes and their tissue environment through cytokine signaling, here represented by transforming growth factor-beta (TGF-β) signaling. We have discussed responses of TGF-β signaling in transition of hepatic stellate cells to myofibroblasts (MFBs), recruitment of tumor-associated macrophages (TAMs), and enrichment of tumor-associated endothelial cells (TECs). The malignant hepatocytes also secrete various factors such as platelet-derived growth factors (PDGFs), vascular endothelial growth factor (VEGF), and TGF-β. TGF-β, a super-family of cytokines, creates tumor microenvironment by interacting through other growth factors (epidermal growth factor receptor (EGFR), PDGF, fibroblast growth factor (FGF), hepatocyte growth factor (HGF), VEGF), cytokines and chemokines, and extracellular matrix (ECM) remodeling. Hence, the HCC tumor microenvironment may now be recognized as an important participant of tumor progression to act as potential target to systemic therapies compared to targeted therapies.
PMCID: PMC3988670  PMID: 24741325
TGF-β; tumor microenvironment; cancer stem cells; hepatocellular carcinoma
4.  Severe Hemorrhage from the Umbilical Cord at Birth: A Preventable Cause of Neonatal Shock 
Case Reports in Pediatrics  2013;2013:317627.
Posthemorrhagic anemia is a rare but important cause of anemia in neonates, second only to hemolytic anemia of newborn. Most cases of posthemorrhagic anemia are reported from fetomaternal hemorrhage or umbilical cord accidents in utero. This case report describes a preterm infant who developed severe anemia and shock immediately after delivery related to an acute hemorrhage through patent umbilical cord vessels secondary to a tear in the umbilical cord at the site of cord clamping. We believe that umbilical cord bleeding from errors in cord clamping could be an important cause of acute blood loss in the delivery room and that it may result in significant clinical morbidity, especially in extremely premature infants.
PMCID: PMC3835191  PMID: 24294534
5.  Diagnostic Modalities of Precancerous and Cancerous Cervical Lesions with Special Emphasis on CD31 Angiogenesis Factor as a Marker 
Objectives. To evaluate the role of angiogenesis tumor marker CD31 in the detection of precancerous and cancerous cervical lesions and to compare its efficacy with colposcopy and histopathology. Materials and Methods. 230 patients with a suspicious looking cervix and an abnormal Pap smear attending the Outpatient Department of Obstetrics and Gynaecology of GSVM Medical College were subjected to a colposcopic examination. 180 patients with suspected colposcopic findings were subjected to a colposcopic directed biopsy. Biopsy tissues were sent for histopathological examination out of which 50 biopsied samples were sent for immunostaining of CD-31. Statistical analysis was done. Results. Comparison of microvessel density (MVD) count by haematoxylin and eosin staining (HE) and immunostaining of CD31 in preinvasive group were 4.012 ± 2.57 and 5.44 ± 2.21, respectively, and in invasive group were 9.18 ± 2.32 and 12.82 ± 4.07, respectively, which showed that MVD was higher by CD31 both in preinvasive and invasive group, and it was statistically significant. Conclusion. Angiogenesis is a marker of tumor progression, and CD31 fixes up vessel better as compared to HE, so aggressiveness of the tumor can be better predicted by MVD-CD31 as compared to MVD-HE.
PMCID: PMC3791664  PMID: 24167753
6.  Morphological redescription and molecular characterization of three species of Travassosinematidae (Nematoda: Oxyurida: Thelastomatoidea) from Gryllotalpa africana Beauv (Orthoptera: Gryllotalpidae) 
Bioinformation  2013;9(16):818-823.
Binema mirzaia (Basir, 1942a) Basir, 1956, Cameronia nisari (Parveen and Jairajpuri, 1985) Adamson and Van Waerebeke, 1992a and Mirzaiella meerutensis Singh and Malti, 2003 are redescribed morphologically along with molecular identification from the intestine of mole cricket Gryllotalpa africana. Molecular characterization was carried out using the D2–D3 expansion domains of the 18S ribosomal DNA region. This study first time presents molecular data for the above three nematode species.
PMCID: PMC3796883  PMID: 24143052
Nematode; Travassosinematidae; Molecular characterization; Meerut; India
7.  Insulin catalyzes the curcumin-induced wound healing: An in vitro model for gingival repair 
Indian Journal of Pharmacology  2012;44(4):458-462.
Human gingival fibroblasts (hGFs) play a major role in the maintenance and repair of gingival connective tissue. The mitogen insulin with IGFs etc. synergizes in facilitating wound repair. Although curcumin (CUR) and insulin regulate apoptosis, their impact as a combination on hGF in wound repair remains unknown. Our study consists of: 1) analysis of insulin-mediated mitogenesis on CUR-treated hGF cells, and 2) development of an in vitro model of wound healing.
Materials and Methods:
Apoptotic rate in CUR-treated hGF cells with and without insulin was observed by AnnexinV/PI staining, nuclear morphological analysis, FACS and DNA fragmentation studies. Using hGF confluent cultures, wounds were mechanically created in vitro and incubated with the ligands for 48 h in 0.2% fetal bovine serum DMEM.
CUR alone showed dose-dependent (1–50 μM) effects on hGF. Insulin (1 μg/ml) supplementation substantially enhanced cell survival through up-regulation of mitogenesis/anti-apoptotic elements.
The in vitro model for gingival wound healing establishes that insulin significantly enhanced wound filling faster than CUR-treated hGF cells over 48 h. This reinforces the pivotal role of insulin in supporting CUR-mediated wound repair. The findings have significant bearing in metabolic dysfunctions, e.g. diabetes, atherosclerosis, etc., especially under Indian situations.
PMCID: PMC3469947  PMID: 23087505
Curcumin; fibroblast; gingival healing; insulin; regeneration
8.  Polyphenols Sensitization Potentiates Susceptibility of MCF-7 and MDA MB-231 Cells to Centchroman 
PLoS ONE  2012;7(6):e37736.
Polyphenols as “sensitizers” together with cytotoxic drugs as “inducers” cooperate to trigger apoptosis in various cancer cells. Hence, their combination having similar mode of mechanism may be a novel approach to enhance the efficacy of inducers. Additionally, this will also enable to achieve the physiological concentrations facilitating significant increase in the activity at concentrations which the compound can individually provide. Here we propose that polyphenols (Resveratrol (RES) and Curcumin (CUR)) pre-treatment may sensitize MCF-7/MDA MB-231 (Human Breast Cancer Cells, HBCCs) to Centchroman (CC, antineoplastic agent). 6 h pre-treated cells with 10 µM RES/CUR and 100 µM RES/30 µM CUR doses, followed by 10 µM CC for 18 h were investigated for Ser-167 ER-phosphorylation, cell cycle arrest, redox homeostasis, stress activated protein kinase (SAPKs: JNK and p38 MAPK) pathways and downstream apoptosis effectors. Low dose RES/CUR enhances the CC action through ROS mediated JNK/p38 as well as mitochondrial pathway in MCF-7 cells. However, RES/CUR sensitization enhanced apoptosis in p53 mutant MDA MB-231 cells without/with involvement of ROS mediated JNK/p38 adjunct to Caspase-9. Contrarily, through high dose sensitization in CC treated cells, the parameters remained unaltered as in polyphenols alone. We conclude that differential sensitization of HBCCs with low dose polyphenol augments apoptotic efficacy of CC. This may offer a novel approach to achieve enhanced action of CC with concomitant reduction of side effects enabling improved management of hormone-dependent breast cancer.
PMCID: PMC3387160  PMID: 22768036
9.  Nanoparticles that Communicate In Vivo to Amplify Tumour Targeting 
Nature materials  2011;10(7):545-552.
Nanomedicines have enormous potential to improve the precision of cancer therapy, yet our ability to efficiently home these materials to regions of disease in vivo remains very limited. Inspired by the ability for communication to improve targeting in biological systems, such inflammatory cell recruitment to sites of disease, we construct systems where synthetic biological and nanotechnological components communicate to amplify disease targeting in vivo. These systems are composed of ‘Signalling’ modules (nanoparticles or engineered proteins) that target tumours and then locally active the coagulation cascade to broadcast tumour location to clot-targeted ‘Receiving’ nanoparticles in circulation that carry a diagnostic or therapeutic cargo, thereby amplifying their delivery. We show that communicating nanoparticle systems can be composed from multiple types of Signalling and Receiving modules, can transmit information via multiple molecular pathways in coagulation, can operate autonomously, and can target over 40-fold higher doses of chemotherapeutics to tumours than non-communicating controls.
PMCID: PMC3361766  PMID: 21685903
10.  Impact of Preexisting Adenovirus Vector Immunity on Immunogenicity and Protection Conferred with an Adenovirus-Based H5N1 Influenza Vaccine 
PLoS ONE  2012;7(3):e33428.
The prevalence of preexisting immunity to adenoviruses in the majority of the human population might adversely impact the development of adaptive immune responses against adenovirus vector-based vaccines. To address this issue, we primed BALB/c mice either intranasally (i.n.) or intramuscularly (i.m.) with varying doses of wild type (WT) human adenovirus subtype 5 (HAd5). Following the development of immunity against HAd5, we immunized animals via the i.n. or i.m. route of inoculation with a HAd vector (HAd-HA-NP) expressing the hemagglutinin (HA) and nucleoprotein (NP) of A/Vietnam/1203/04 (H5N1) influenza virus. The immunogenicity and protection results suggest that low levels of vector immunity (<520 virus-neutralization titer) induced by priming mice with up to 107 plaque forming units (p.f.u.) of HAd-WT did not adversely impact the protective efficacy of the vaccine. Furthermore, high levels of vector immunity (approximately 1500 virus-neutralization titer) induced by priming mice with 108 p.f.u. of HAd-WT were overcome by either increasing the vaccine dose or using alternate routes of vaccination. A further increase in the priming dose to 109 p.f.u. allowed only partial protection. These results suggest possible strategies to overcome the variable levels of human immunity against adenoviruses, leading to better utilization of HAd vector-based vaccines.
PMCID: PMC3303828  PMID: 22432020
11.  Ameliorative effects of Panax quinquefolium on experimentally induced reflux oesophagitis in rats 
Background & objectives:
Reflux oesophagitis (RE), is one of the most prevalent chronic gastrointestinal disorders commonly referred to as gastroesophageal reflux disease (GERD) and requires long term therapy. The present study was designed to investigate the protective effects of Panax quinquefolium (PQ), administered with variable doses, on experimentally induced reflux oesophagitis (RE) in rats.
Forty two female Sprague-Dawley (180-220 g) rats were randomly divided to receive standardized root powder of PQ (50-200mg/kg, po), standard anti-reflux (omeprazole, 5 mg/kg, ip) and anti-oxidant (α-tocopherol, 16 mg/kg, po). After 45 min drug pretreatment, RE was produced in rats by simultaneous ligation of the pyloric end and forestomach. Several parameters, including macroscopic lesion index, glutathione system, lipid peroxidation (LPO) and tissue myeloperoxidase (MPO) activity were measured. Alterations in ICAM-1, CINC-2 and MCP-1 gene expression were examined through reverse transcriptase polymerase chain reaction (RT-PCR).
PQ significantly attenuated the severity of the macroscopic signs of RE-induced tissue damage, replenished the depleted GSH level and reduced the RE-associated LPO levels dose dependently. In contrast, omeprazole though effectively improved the mucosal damage, it failed to bring significant attenuation of RE-associated changes in LPO, GSH level and MPO activity. α-Tocopherol significantly ameliorated RE-induced tissue injury and improved LPO level and GSH/GSSG ratio but failed to counteract RE-induced MPO activity. PQ at dose of 100 mg/kg significantly downregulated ICAM-1 and CINC-2 expression whereas it showed no effect over MCP-1 expression.
Interpretation & conclusions:
The present data indicate that PQ protects against RE-induced oesophageal damage via a mechanism that inhibits the influx of inflammatory cell to oesophagus and a consequence excessive oxidative load, opening the avenue to its promising protective role in patients with gastroesophageal reflux disease (GERD).
PMCID: PMC3361880  PMID: 22561630
Acid reflux; anti-inflammatory; oesophagitis; oxidative stress; Panax quinquefolium
12.  Intellectual property rights and patents in perspective of Ayurveda 
Ayu  2012;33(1):20-26.
Ayurveda is getting its due recognition as a rationale system of medicine worldwide despite the fact that medical and scientific fraternity of the globe has very strong opposite opinion regarding safety and efficacy of Ayurvedic medicines. Meanwhile, provisions of Intellectual Property Rights under World Intellectual Property Organization (WIPO) and Patents have attracted many individuals and organizations to explore possibilities of commercial benefits with Ayurvedic traditional knowledge. Although rules are not favoring to grant a patent on prior published knowledge, biopiracy managed grant of Patent on knowledge of Ayurvedic medicinal plants which has been successfully checked with references of data base of Traditional Knowledge Digital Library (TKDL). Current provisions of the Patent law of India are obstructive in nature for getting patent on Ayurvedic medicines. If we have to invite researchers from basic science to ensure quality, safety and efficacy of Ayurvedic medicines, there is an urgent need to amend laws of patent with pragmatic promotional policies. This will encourage more patents on numerous pharmaceutical, nutraceutical and cosmaceutical products based on Ayurveda. As every action of today's world is based on economic criteria so why stakeholders of Ayurveda should be deprived of it. New inventions would drive acceptance of Ayurveda as a global system of medicine.
PMCID: PMC3456857  PMID: 23049179
Ayurvedic pharmaceuticals; cosmaceuticals; IPR; nutraceuticals; product patent; TKDL
13.  A progressive review of Sandhana kalpana (Biomedical fermentation): An advanced innovative dosage form of Ayurveda 
Ayu  2011;32(3):408-417.
Sandhana kalpana (biomedical fermented formulations) are one of the best dosage forms of Ayurveda in practice since thousands of years. In order to prepare these medicaments, certain sets of conditions are prearranged, which lead to fermentation. Thus, products bequeath with self-generated ethyl alcohol, which potentiate these preparations (Asava–Arishta), pharmaceutically and therapeutically. Commonly, medicinal and commercial components of these formulations are prompting many researchers to contribute in manufacturing, quality control, safety, and efficacy of these formulations. To cope up with this, literature related to Asava–Arishta has been surveyed from the Vedic period to recent publications of Government of India, ie, Ayurvedic Formulary of India, and presented briefly here. In this review paper, we have discussed pioneering facts such as nature and amount of carbohydrate, type of containers, optimum temperature, variety and relevance of initiator of fermentation, manufacturing, regulatory rules, and business aspects of Asava-Arishta. After going through this basic information, any academician or researcher may show a way to further strengthen this dosage form.
PMCID: PMC3326893  PMID: 22529661
Asava; Arishta; ethyl alcohol; fermentation; quality control; Sandhana kalpana
14.  Herbo Mineral Formulations (Rasaoushadhies) of Ayurveda an Amazing Inheritance of Ayurvedic Pharmaceutics 
Ancient Science of Life  2010;30(1):18-26.
The one of the oldest system of medicine, Ayurveda is momentous in audience of worldwide on virtue of its holistic approach of life. Formulations of Ayurveda consist of substances of herbal, mineral/metal and animal origin which are processed pharmaceutical to have therapeutic effects. This is attribute of processes of Shodhan (purification/potentiation), Bhavana (impregation /levigation) and Marana (incineration/calcinations) of Rasa Shastra which acclimatize these toxic industrial matter to a effective remedies known as herbo mineral formulations (Rasaoushadhies) of Ayurveda. In recent past there is prevalence of some doubt on safety and efficacy of these medicines. In this review paper we tried to justify application of these medicines as these are time tested and showed wonderful clinical adaptability. We also attempted to establish new facts of figures of core science in explanation of these medicines.
PMCID: PMC3336271  PMID: 22557419
Shodhan ’a-MaranaBhasma; Nanotechnology; Metallopharmaceuticals
15.  Reduced Acute Inflammatory Responses to Microgel Conformal Coatings 
Biomaterials  2008;29(35):4605-4615.
Implantation of synthetic materials into the body elicits inflammatory host responses that limit medical device integration and biological performance. This inflammatory cascade involves protein adsorption, leukocyte recruitment and activation, cytokine release, and fibrous encapsulation of the implant. We present a coating strategy based on thin films of poly(N-isopropylacrylamide) hydrogel microparticles (i.e. microgels) cross-linked with poly(ethylene glycol) diacrylate. These particles were grafted onto a clinically relevant polymeric material to generate conformal coatings that significantly reduced in vitro fibrinogen adsorption and primary human monocytes/macrophage adhesion and spreading. These microgel coatings also reduced leukocyte adhesion and expression of pro-inflammatory cytokines (TNF-α, IL-1β, MCP-1) in response to materials implanted acutely in the murine intraperitoneal space. These microgel coatings can be applied to biomedical implants as a protective coating to attenuate biofouling, leukocyte adhesion and activation, and adverse host responses for biomedical and biotechnological applications.
PMCID: PMC2585524  PMID: 18804859
cell adhesion; cytokine; foreign body response; hydrogel; macrophage; polyethylene terephthalate
16.  Insights into the effects of α-synuclein expression and proteasome inhibition on glutathione metabolism through a dynamic in silico model of Parkinson's disease: validation by cell culture data 
Free radical biology & medicine  2008;45(9):1290-1301.
Dopaminergic neurodegeneration during Parkinson disease (PD) involves several pathways including proteasome inhibition, α-synuclein (α-syn) aggregation, mitochondrial dysfunction, and glutathione (GSH) depletion. We have utilized a systems biology approach and built a dynamic model to understand and link the various events related to PD pathophysiology. We have corroborated the modeling data by examining the effects of α-syn expression in the absence and presence of proteasome inhibition on GSH metabolism in dopaminergic neuronal cultures. We report here that the expression of the mutant A53T form of α-syn is neurotoxic and causes GSH depletion in cells after proteasome inhibition, compared to wild-type α-syn-expressing cells and vector control. Modeling data predicted that GSH depletion in these cells was due to ATP loss associated with mitochondrial dysfunction. ATP depletion elicited by combined A53T expression and proteasome inhibition results in decreased de novo synthesis of GSH via the rate-limiting enzyme γ-glutamyl cysteine ligase. Based on these data and other recent reports, we propose a novel dynamic model to explain how the presence of mutated α-syn protein or proteasome inhibition may individually impact on mitochondrial function and in combination result in alterations in GSH metabolism via enhanced mitochondrial dysfunction.
PMCID: PMC2744580  PMID: 18761401
Parkinson's disease; Neurodegeneration; α-Synuclein; Protein aggregation; Proteasome inhibition; Mitochondrial dysfunction; Glutathione; Systems biology; Dynamic model; In silico; Free radicals
17.  Statistically significant association of the single nucleotide polymorphism (SNP) rs13181 (ERCC2) with predisposition to Squamous Cell Carcinomas of the Head and Neck (SCCHN) and Breast cancer in the north Indian population 
Non-synonymous single nucleotide polymorphisms (SNPs) within vital DNA repair genes may cause reduction of activity leaving the genome unrepaired resulting in genomic instability and cancer.
Materials and methods
The present endeavour involved study on the association of the SNP rs13181 (Lys751Gln/A18911C) in the Nucleotide Excision Repair (NER) pathway gene ERCC2 (excision repair cross-complementing rodent repair deficiency, complementation group 2) with the risks of Squamous Cell Carcinomas of the Head and Neck (SCCHN) and Breast cancer using a case-control based association study among 685 (400 controls and 285 SCCHN-affected cases) and 395 (227 normal healthy female controls and 168 breast cancer cases) ethnically-matched samples, respectively from north India using Polymerase Chain Reaction followed by Restriction Fragment Length Polymorphism (PCR-RFLP) analysis.
Results showed significant association of rs13181 homozygous mutant (CC) [Odds Ratio (OR) 4.412, 95% Confidence Interval (CI) 2.413 to 8.068], heterozygous (AC) (OR 2.086, 95% CI 1.246 to 3.492) and combined mutant (AC + CC) (OR 2.672, 95% CI 1.647 to 4.334) genotypes with predisposition to Breast cancer. Statistically significant increase in SCCHN risk was also associated with the mutant genotypes of rs13181 (ERCC2), viz. homozygous mutant (CC) (OR 1.680, 95% CI 1.014 to 2.784), heterozygous (AC) (OR 1.531, 95% CI 1.092 to 2.149) and combined mutant (AC + CC) (OR 1.560, 95% CI 1.128 to 2.158) genotypes.
The results of this case-control study indicate that the polymorphism rs13181 might be a risk factor for predisposition towards SCCHN and breast cancer among north Indian subpopulations.
PMCID: PMC2724389  PMID: 19615095
18.  Bovine adenoviral vector-based H5N1 influenza vaccine overcomes exceptionally high levels of pre-existing immunity against human adenovirus 
Because of high prevalence of adenovirus (Ad) infections in humans, it is believed that preexisting Ad-neutralizing antibodies (‘vector immunity’) may negatively impact the immune response to vaccine antigens when delivered by human Ad (HAd) vectors. In order to evaluate whether bovine adenovirus subtype 3 (BAd3), a nonhuman Ad vector can effectively elude high levels of preexisting vector immunity, naïve or HAd serotype 5 (HAd)-primed mice were immunized with BAd-H5HA [BAd3 vector expressing the hemagglutinin (HA) gene from H5N1 influenza virus]. Even in the presence of very high levels of HAd-specific neutralizing antibody, no significant reductions in HA-specific humoral and cell-mediated immune responses were observed in HAd-primed mice immunized with BAd-H5HA. In naïve mice immunized with HAd-H5HA (HAd5 vector expressing H5N1 HA) and boosted with BAd-H5HA, the humoral responses elicited were significantly higher (P<0.01) than with either with either HAd-H5HA or BAd-H5HA alone, while the CMI responses were comparable in the groups. This finding underlines the importance of a heterologous prime-boost approach for achieving an enhanced immune response. The immunization of naïve or HAd-primed mice with BAd-H5HA bestowed full protection from morbidity and mortality following a potentially lethal challenge with A/Hong Kong/483/97. These results demonstrate the importance of BAd vectors as an alternate or supplement to HAd vectors for influenza pandemic preparedness.
PMCID: PMC2700267  PMID: 18301400
19.  A Broadly Protective Vaccine against Globally Dispersed Clade 1 and Clade 2 H5N1 Influenza Viruses 
The Journal of infectious diseases  2008;197(8):1185-1188.
Development of effective and immunogenic vaccines against highly pathogenic avian influenza H5N1 viruses with the potential to cause a pandemic is a public health priority. The global demand for a vaccine cannot be met in the event of an influenza pandemic because of the limited capacity to manufacture egg-derived vaccines as well as potential problems with the availability of embryonated eggs. Thus, there is an urgent need to develop alternative, egg-independent vaccines. We developed an adenoviral vector-based vaccine that contains hemagglutinin proteinfrom clade 1 and clade 2 viruses, as well as conserved nucleoprotein, to broaden the vaccine coverage against H5N1 viruses.
PMCID: PMC2658634  PMID: 18462165
Pandemic Influenza; Vaccine; Adenoviral vector; Avian influenza virus
20.  Synthesis of Multifunctional Nanogels Using a Protected Macromonomer Approach 
Colloid and polymer science  2008;286(8-9):1061-1069.
Nanoparticles possessing multiple functionalities provide synthetic handles for varied surface chemistries, making them useful for a range of applications such as biotargeting and drug delivery. However, the combination of interfering functionalities on the same particle is often challenging. We have employed a synthetic scheme involving chemical protection/deprotection to combine interfering functional groups on the same hydrogel nanoparticle. The synthesis of amine-containing poly(N-isopropylacrylamide) nanogels was carried out via free radical precipitation polymerization by incorporating a Fmoc-protected amine PEG macromonomer. The Fmoc group was then removed to obtain free amines, which were shown to be available for conjugation. We further explored pNIPAm-co-acrylic acid nanogels with a protected amine-PEG, yielding zwitterionic particles. With careful attention to the order of the chemoligation and deprotection steps, these interfering functional groups can be forced to behave in a pseudo-orthogonal fashion, allowing for multiple chemoligation steps that employ both the amine and carboxylic acid groups.
PMCID: PMC2600853  PMID: 19079744
Nanogels; Chemoligation; Orthogonal functionality; Bioconjugation
21.  Bioresponsive Mesoporous Silica Nanoparticles for Triggered Drug Release 
Journal of the American Chemical Society  2011;133(49):19582-19585.
Mesoporous silica nanoparticles (MSNPs) have garnered a great deal of attention as potential carriers for therapeutic payloads. However, achieving triggered drug release from MSNPs in vivo has been challenging. Here, we describe the synthesis of stimulus-responsive polymer-coated MSNPs and the loading of therapeutics into both the core and shell domains. We characterize MSNP drug-eluting properties in vitro and demonstrate that the polymer-coated MSNPs release doxorubicin in response to proteases present at a tumor site in vivo, resulting in cellular apoptosis. These results demonstrate the utility of polymer-coated nanoparticles in specifically delivering an antitumor payload.
PMCID: PMC3295203  PMID: 21981330
22.  Functional Delivery of siRNA in Mice Using Dendriworms 
ACS Nano  2009;3(9):2495-2504.
Small interfering RNAs (siRNAs) mediate cleavage of specific, complementary mRNA sequences and thus regulate gene expression. Not surprisingly, their use for treatment of diseases that are rooted in aberrant gene expression, such as cancer, has become a paradigm that has gained wide interest. Here, we report the development of dendrimer-conjugated magnetofluorescent nanoworms that we call “dendriworms” as a modular platform for siRNA delivery in vivo. This platform maximizes endosomal escape to robustly produce protein target knockdown in vivo, and is tolerated well in mouse brain. We demonstrate that siRNA-carrying dendriworms can be readily internalized by cells and enable endosomal escape across a wide range of loading doses, whereas dendrimers or nanoworms alone are inefficient. Further, we show that dendriworms carrying siRNA against the epidermal growth factor receptor (EGFR) reduce protein levels of EGFR in human glioblastoma cells by 70−80%, 2.5-fold more efficiently than commercial cationic lipids. Dendriworms were well-tolerated after 7-days of convection-enhanced delivery to the mouse brain and in an EGFR-driven transgenic model of glioblastoma, anti- EGFR dendriworms led to specific and significant suppression of EGFR expression. Collectively, these data establish dendriworms as a multimodal platform that enables fluorescent tracking of siRNA delivery in vivo, cellular entry, endosomal escape, and knockdown of target proteins.
PMCID: PMC2828182  PMID: 19673534
dendrimer; siRNA; nanoparticle; EGFR; glioblastoma
23.  Effect of Nanoparticle Conjugation on Gene Silencing by RNA Interference 
RNA interference (RNAi) is a cellular process whereby the silencing of a particular gene is mediated by short RNAs (siRNAs). Although siRNAs have great therapeutic potential, cellular delivery has been a challenge. Nanoparticle-siRNA conjugates have emerged as potential delivery vehicles; however, reports describing the effects of nanoparticle conjugation on RISC incorporation and subsequent gene silencing have been mixed. In this report, we have systematically evaluated the effect of siRNA coupling strategies using a model nanoparticle system with varying conjugation schemes. We show that the accessibility of the siRNA linked to the nanoparticle and the lability of the cross-linker are critical for efficient gene knockdown.
PMCID: PMC2968757  PMID: 20518524

Results 1-23 (23)