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Find video protocols related to scientific articles indexed in Pubmed.
Ru(II)-catalyzed selective C-H amination of xanthones and chromones with sulfonyl azides: synthesis and anticancer evaluation.
J. Org. Chem.
PUBLISHED: 09-24-2014
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A ketone-assisted ruthenium-catalyzed selective amination of xanthones and chromones C-H bonds with sulfonyl azides is described. The reactions proceed efficiently with a broad range of substrates with excellent functional group compatibility. This protocol provides direct access to 1-aminoxanthones, 5-aminochromones, and 5-aminoflavonoid derivatives known to exhibit potent anticancer activity.
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Health-related quality of life in women exposed to wood smoke while cooking.
Int. J. Tuberc. Lung Dis.
PUBLISHED: 09-09-2014
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Using the abbreviated World Health Organization Quality of Life (WHOQOL-Bref) questionnaire, we evaluated the effect of exposure to smoke from wood combustion while cooking on health-related quality of life (HRQL) in 85 women using wood and 85 women using liquefied petroleum gas (LPG) as cooking fuel in India. Age, years of cooking and hours spent daily in the kitchen were similar between women in the two groups. WHOQOL-Bref transformed scores in psychological, social relationships and environment domains were significantly lower in women in using wood than in those using LPG, suggesting that HRQL was impaired across domains among these women.
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Dinuclear [{(p-cym)RuCl}2(?-phpy)](PF6)2 and heterodinuclear [(ppy)2Ir(?-phpy)Ru(p-cym)Cl](PF6)2 complexes: synthesis, structure and anticancer activity.
Dalton Trans
PUBLISHED: 08-28-2014
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Phpy bridged homodinuclear Ru-Ru () and heterodinuclear Ir-Ru complexes () have been developed. Complex induces autophagy towards the cisplatin resistant human breast cancer (MCF7) cell line, whereas is inactive.
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A clathrin coat assembly role for the muniscin protein central linker revealed by TALEN-mediated gene editing.
Elife
PUBLISHED: 07-23-2014
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Clathrin-mediated endocytosis is an evolutionarily ancient membrane transport system regulating cellular receptivity and responsiveness. Plasmalemma clathrin-coated structures range from unitary domed assemblies to expansive planar constructions with internal or flanking invaginated buds. Precisely how these morphologically-distinct coats are formed, and whether all are functionally equivalent for selective cargo internalization is still disputed. We have disrupted the genes encoding a set of early arriving clathrin-coat constituents, FCHO1 and FCHO2, in HeLa cells. Endocytic coats do not disappear in this genetic background; rather clustered planar lattices predominate and endocytosis slows, but does not cease. The central linker of FCHO proteins acts as an allosteric regulator of the prime endocytic adaptor, AP-2. By loading AP-2 onto the plasma membrane, FCHO proteins provide a parallel pathway for AP-2 activation and clathrin-coat fabrication. Further, the steady-state morphology of clathrin-coated structures appears to be a manifestation of the availability of the muniscin linker during lattice polymerization.
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Electrochemical detection of p-ethylguaiacol, a fungi infected fruit volatile using metal oxide nanoparticles.
Analyst
PUBLISHED: 06-05-2014
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Nanoparticles of TiO(2) or SnO(2) on screen-printed carbon (SP) electrodes have been developed for evaluating their potential application in the electrochemical sensing of volatiles in fruits and plants. These metal oxide nanoparticle-modified electrodes possess high sensitivity and low detection limit for the detection of p-ethylguaiacol, a fingerprint compound present in the volatile signature of fruits and plants infected with a pathogenic fungus Phytophthora cactorum. The electroanalytical data obtained using cyclic voltammetry and differential pulse voltammetry showed that both SnO(2) and TiO(2) exhibited high sensitivity (174-188 ?A cm(-2) mM(-1)) and low detection limits (35-62 nM) for p-ethylguaiacol detection. The amperometric detection was highly repeatable with RSD values ranging from 2.48 to 4.85%. The interference studies show that other common plant volatiles do not interfere in the amperometric detection signal of p-ethylguaiacol. The results demonstrate that metal oxides are a reasonable alternative to expensive electrode materials such as gold or platinum for amperometric sensor applications.
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A phosphotyrosine switch for cargo sequestration at clathrin-coated buds.
J. Biol. Chem.
PUBLISHED: 05-05-2014
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The AP-2 clathrin adaptor complex oversees endocytic cargo selection in two parallel but independent manners. First, by physically engaging peptide-based endocytic sorting signals, a subset of clathrin-dependent transmembrane cargo is directly collected into assembling buds. Synchronously, by interacting with an assortment of clathrin-associated sorting proteins (CLASPs) that independently select different integral membrane cargo for inclusion within the incipient bud, AP-2 handles additional cargo capture indirectly. The distal platform subdomain of the AP-2 ?2 subunit appendage is a privileged CLASP-binding surface that recognizes a cognate, short ?-helical interaction motif. This signal, found in the CLASPs ?-arrestin and the autosomal recessive hypercholesterolemia (ARH) protein, docks into an elongated groove on the ?2 appendage platform. Tyr-888 is a critical constituent of this spatially confined ?2 appendage contact interface and is phosphorylated in numerous high-throughput proteomic studies. We find that a phosphomimetic Y888E substitution does not interfere with incorporation of expressed ?2-YFP subunit into AP-2 or alter AP-2 deposition at surface clathrin-coated structures. The Y888E mutation does not affect interactions involving the sandwich subdomain of the ?2 appendage, indicating that the mutated appendage is folded and operational. However, the Y888E, but not Y888F, switch selectively uncouples interactions with ARH and ?-arrestin. Phyogenetic conservation of Tyr-888 suggests that this residue can reversibly control occupancy of the ?2 platform-binding site and, hence, cargo sorting.
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Photocurrent generation by immobilized cyanobacteria via direct electron transport in photo-bioelectrochemical cells.
Phys Chem Chem Phys
PUBLISHED: 03-20-2014
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Cyanobacteria possess unique and exciting features among photosynthetic microorganisms for energy conversion applications. This study focuses on production of direct electricity using a cyanobacterium called Nostoc sp. (NOS) as a photo-biocatalyst immobilized on carbon nanotubes on the anode of photo-bioelectrochemical cells. By illuminating with light (intensity 76 mW cm(-2)) the NOS immobilized on a carbon nanotube (CNT) modified electrode generated a photocurrent density of 30 mA m(-2) at 0.2 V (vs. Ag/AgCl). The contribution of different photosynthetic pigments in NOS to the light capture was analyzed and chlorophyll-a was found to be the major contributor to light capture followed by phycocyanin. Further investigation using a set of inhibitors revealed that the electrons were redirected predominantly from PSII to the CNT through the plastoquinone pool and quinol oxidase. A rudimentary design photosynthetic electrochemical cell has been constructed using NOS/CNT on the anode and laccase/CNT on the cathode as catalysts. The cell generated a maximum current density of 250 mA m(-2) and a peak power density of 35 mW m(-2) without any mediator. By the addition of 1,4-benzoquinone as a redox mediator, the electricity generation capability was significantly enhanced with a current density of 2300 mA m(-2) and a power density of 100 mW m(-2). The power densities achieved in this work are the highest among 'non-engineered' cyanobacteria based electrochemical systems reported to date.
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Lower limb gigantism, lymphedema, and painful varicosities following a thigh vascular access graft.
Hemodial Int
PUBLISHED: 01-27-2014
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Prosthetic arteriovenous grafts (AVGs) are associated with greater morbidity than autogenous arteriovenous fistulas (AVFs), but their use is indicated when AVF formation is not possible. This report adds to the literature a case of lower limb gigantism, painful varicosities, and lymphedema following long-term use of AVG in the upper thigh. The patient's past medical history included renal transplantation on the same side well before the AVG was inserted and right leg deep vein thrombosis. Suspicion of AVG thrombosis was excluded by Doppler ultrasound, which demonstrated an access flow of 1700?mL/min. A computed tomography (CT) scan of the abdomen and pelvis did not identify the cause of her symptoms. Whereas functional incompetence of the iliac vein valve might be responsible for the varicosities, the extent of hypertrophy in this case raises the suspicion of lymphatic blockage possibly secondary to groin dissection undertaken at the time of graft insertion, in addition to the previous dissection at the time of transplantation. This case highlights the need for minimal groin dissection during AVG insertion, particularly in patients with a history of previous abdominopelvic surgery.
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Laparoscopic peritoneal dialysis catheter (PDC) insertion: does it really make a difference?
J. Nephrol.
PUBLISHED: 01-08-2014
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Permanent peritoneal dialysis (PD) access was first described and introduced in clinical practice more than 40 years ago. It is still undergoing modification and adaptation to various insertion techniques. PD Catheter insertion is commonly performed via one of the three techniques: (a) open surgical, (b) fluoroscopic-guided placement or blind percutaneous placements using a modified Seldinger technique and (c) minimally invasive. Catheter placement is thought to be the key to a successful PD programme and the economic advantages are lost if a patient switches to HD during the 1st year due to failure of PD. The objective of this document was to conduct an evidence-based assessment of a minimally invasive approach to PD catheter insertion, with particular regard to failure rates secondary to catheter dysfunction. Case series and randomised controlled trials suggest that laparoscopic placement of peritoneal dialysis catheters is safe, and useful for insertion of PD catheters in patients who have undergone previous abdominal surgery. An overall success rate of 90% with a less than 5% associated leak rate has been quoted, although a cost benefit analysis has not been performed. However, good grade I evidence is lacking and open surgery may be quicker, though results from on-going trial are awaited with interest.
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Highly sensitive electrochemical detection of methyl salicylate using electroactive gold nanoparticles.
Analyst
PUBLISHED: 09-17-2013
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Electrochemical sensing of methyl salicylate, a key plant volatile has been achieved using a gold nanoparticle (AuNP) modified screen printed carbon electrode (SPCE). The electrochemical response of planar gold electrodes, SPCE and AuNP-SPCE in alkaline electrolyte in the presence and absence of methyl salicylate were studied to understand the amperometric response of various electrochemical reactions. The reaction mechanism includes hydrolysis of methyl salicylate and the oxidation of negative species. The electrochemical responses were recorded using cyclic voltammetry and differential pulse voltammetry techniques, where the results showed characteristic signals for methyl salicylate oxidation. Among the examined electrodes, AuNP-SPCE possessed three fold better sensitivity than planar gold and 35 times better sensitivity than SPCE (at 0.5 V). The methyl salicylate sensing by AuNP-SPCE possessed <5% variation coefficient for repeatability, one week of stable performance with no more than 15% activity loss even if used multiple times (n = 8). Even in the presence of high concentration of interfering compounds such as cis-3-hexenol, hexyl acetate and cis-hexenyl acetate, AuNP-SPCE retained >95% of its methyl salicylate response. The electroanalytical results of soybean extract showed that AuNP-SPCE can be employed for the determination of methyl salicylate in real samples.
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A novel anthracene derivative, MHY412, induces apoptosis in doxorubicin-resistant MCF-7/Adr human breast cancer cells through cell cycle arrest and downregulation of P-glycoprotein expression.
Int. J. Oncol.
PUBLISHED: 08-30-2013
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New potential chemotherapeutic strategies are required to overcome multidrug resistance (MDR) in cancer. This study investigated the anticancer effect of a novel anthracene derivative MHY412 on doxorubicin-resistant human breast cancer (MCF-7/Adr) cells. We measured cell viability and the expression of apoptosis-related genes; in addition, the antitumor activity of MHY412 was confirmed using an in vivo tumor xenograft model. MHY412 significantly inhibited the proliferation of MCF-7/Adr and MCF-7 cells in a concentration-dependent manner. Notably, the half?maximal inhibitory concentration (IC50) values of MHY412 in MCF-7/Adr (0.15 µM) and MCF-7 (0.26 µM) cells were lower than those of doxorubicin (MCF-7/Adr, 13.6 µM and MCF-7, 1.26 µM) after treatment for 48 h. MHY412 at low concentrations induced S phase arrest, but at high concentrations, the number of MCF-7/Adr cells in the sub-G1 phase significantly increased. MHY412-induced sub-G1 phase arrest was associated with inhibition of cyclin, cyclin?dependent kinase 2 (CDK2) and p21 expression in MCF-7/Adr cells. MHY412 markedly reduced P-glycoprotein (P-gp) expression and increased apoptotic cell death in MCF-7/Adr cells. Cleavage of poly-ADP ribose polymerase, reduced Bcl-2 expression, and increased in cytochrome c release in MCF-7/Adr cells confirmed the above results. In addition, MHY412 markedly inhibited tumor growth in a tumor xenograft model of MCF-7/Adr cells. Our data suggest that MHY412 exerts antitumor effects by selectively modulating the genes related to cell cycle arrest and apoptosis. In particular, MHY412 is a new candidate agent for the treatment of Bcl-2 overexpressed doxorubicin-resistant human breast cancer.
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Pelvic girdle pain in Indian postpartum women: a cross-sectional study.
Physiother Theory Pract
PUBLISHED: 07-30-2013
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Abstract During pregnancy or postpartum period many women will experience some degree of pelvic girdle pain (PGP). In India, there is no information about the PGP prevalence and its associated factors evaluated during postpartum period. Purpose: To reveal the prevalence of PGP postpartum in Indian women and identify associated factors with PGP postpartum. Methods: In this cross-sectional study, 284 postpartum women completed a questionnaire and underwent clinical examinations. The clinical examination included pain provocation tests for the pelvic as well as the active straight leg raise (ASLR) test. Possible associating factors were studied by using nonparametric tests and logistic regression analysis. Results: A total of 116 postpartum women (41%) had reported PGP at the time of the examination. A stepwise logistic regression analysis was performed to reveal associated factors. In the final model, factors such as (1) Caesarean delivery (adjusted OR, 2.0; 95% CI, 1.3-4.9); (2) ASLR test score ?4 (adjusted OR, 2.3; 95% CI, 1.2-3.3); (3) Unilateral P4 test (adjusted OR, 1.8; 95% CI, 1.1-3.0); and (4) Sitting position during feeding (adjusted OR, 1.5; 95% CI, 0.9-2.8) were associated with the PGP. Conclusion: We found a high prevalence of PGP in Indian women during the first three months of postpartum period. Our finding suggests that unilateral posterior pelvic pain provocation test (P4), ASLR test score ?4, caesarean section delivery and sitting in breast-feeding posture were associated with increased risk of PGP during postpartum.
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Pelvic girdle pain after childbirth: the impact of mode of delivery.
J Back Musculoskelet Rehabil
PUBLISHED: 07-30-2013
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During pregnancy or postpartum period, several women experience some degree of pelvic girdle pain (PGP). In India, information is lacking about the prevalence and possible risk factors of PGP evaluated during postpartum period. This study aims to determine the prevalence of PGP in postpartum women who underwent vaginal or caesarean mode of delivery and to estimate possible associated factors with or without PGP in both modes of deliveries.
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Renal Transplantation from Elderly Living Donors.
J Transplant
PUBLISHED: 07-14-2013
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Acceptance of elderly living kidney donors remains controversial due to the higher incidence of comorbidity and greater risk of postoperative complications. This is a review of publications in the English language between 2000 and 2013 about renal transplantation from elderly living donors to determine trends and effects of donation, and the outcomes of such transplantation. The last decade witnessed a 50% increase in living kidney donor transplants, with a disproportionate increase in donors >60 years. There is no accelerated loss of kidney function following donation, and the incidence of established renal failure (ERF) and hypertension among donors is similar to that of the general population. The overall incidence of ERF in living donors is about 0.134 per 1000 years. Elderly donors require rigorous assessment and should have a predicted glomerular filtration rate of at least 37.5?mL/min/1.73?m(2) at the age of 80. Though elderly donors had lower glomerular filtration rate before donation, proportionate decline after donation was similar in both young and elderly groups. The risks of delayed graft function, acute rejection, and graft failure in transplants from living donors >65 years are significantly higher than transplants from younger donors. A multicentred, long-term, and prospective database addressing the outcomes of kidneys from elderly living donors is recommended.
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Perforated Meckels Diverticulum Lithiasis: An Unusual Cause of Peritonitis.
Case Rep Surg
PUBLISHED: 03-31-2013
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Meckels diverticulum is the commonest congenital malformation of gastrointestinal tract and represents a persistent remnant of the omphalomesenteric duct. Although it mostly remains silent, it can present as bleeding, perforation, intestinal obstruction, intussusception, and tumours. These complications, especially bleeding, tend to be more common in the paediatric group and intestinal obstruction in adults. Stone formation (lithiasis) in Meckels diverticulum is rare. We report a case of Meckels diverticulum lithiasis which presented as an acute abdomen in an otherwise healthy individual. The patient underwent an exploratory laparotomy which revealed a perforated Meckels diverticulum with lithiasis; a segmental resection with end-to-end anastomosis of small bowel was performed. Patient recovery was delayed due to pneumonia, discharged on day 20 with no further complications at 6 months following surgery.
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A comprehensive review on SAR of curcumin.
Mini Rev Med Chem
PUBLISHED: 02-11-2013
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Curcumin, a natural diaryl heptanoid continues to be used as an alternative medicinal agent in many parts of South East Asia for treatment of many ailments. It can be usually obtained from substituted aryl aldehydes and acetylacetone and this route enables synthesis of a diverse set of curcumin analogues. Numerous analogues have been synthesized and tested by several researchers to investigate their activity against known biological targets and to improve upon the pharmacological and ADME profile by modifying substitutions on aromatic rings, ?-diketone moiety and two flanking double bonds conjugated to the ?-diketone moiety. Successful synthesis of such derivatives with modifications has resulted in the development of potential anticancer candidates that target various stages in cancer cell growth and development. Based on the evidences in modifications of these three functional elements, we have attempted to summarize the structure activity relationship of molecules which can be further utilized by researchers in medicinal chemistry in exploring the structure of curcumin.
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Thymoglobulin and its use in renal transplantation: a review.
Am. J. Nephrol.
PUBLISHED: 01-22-2013
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Thymoglobulin (Thymoglobulin®; Genzyme, Cambridge, Mass., USA) is a polyclonal antibody which has been used in the field of transplantation over the last four decades. With an initial hesitancy, it is widely used now in the prevention and treatment of rejection following renal transplantation. Thymoglobulins lack of nephrotoxic properties (unlike calcineurin inhibitors) may potentiate it to be a very useful induction therapy during the early days following transplantation, particularly in a donation after circulatory death programme. More recently its role in conjunction with inhibitors of terminal complement activation has been shown to be beneficial in cross-match-positive transplantation. This review article consolidates up-to-date available evidence to address the therapeutic role of thymoglobulin in immunological tolerance, ischemia perfusion, live donor transplantation, delayed graft function, prevention and treatment of rejection, graft survival and post-transplant lymphoproliferative disorder following renal transplantation.
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A novel histone deacetylase (HDAC) inhibitor MHY219 induces apoptosis via up-regulation of androgen receptor expression in human prostate cancer cells.
Biomed. Pharmacother.
PUBLISHED: 01-07-2013
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Histone deacetylase (HDAC) inhibitors are a new class of anticancer agents that act by inhibiting cancer cell proliferation and inducing apoptosis in various cancer cell lines. To investigate the anticancer effect of a novel histone deacetylase (HDAC) inhibitor MHY219, its efficacy was compared to that of suberoylanilide hydroxamic acid (SAHA) in human prostate cancer cells. The anticancer effects of MHY219 on cell viability, HDAC enzyme activity, cell cycle regulation, apoptosis and other biological assays were performed. MHY219 was shown to enhance the cytotoxicity on DU145 cells (IC??, 0.36 ?M) when compared with LNCaP (IC??, 0.97 ?M) and PC3 cells (IC??, 5.12 ?M). MHY219 showed a potent inhibition of total HDAC activity when compared with SAHA. MHY219 increased histone H3 hyperacetylation and reduced the expression of class I HDACs (1, 2 and 3) in prostate cancer cells. MHY219 effectively increased the sub-G1 fraction of cells through p21 and p27 dependent pathways in DU145 cells. MHY219 significantly induced a G2/M phase arrest in DU145 and PC3 cells and arrested the cell cycle at G0/G1 phase in LNCaP cells. Furthermore, MHY219 effectively increased apoptosis in DU145 and LNCaP cells, but not PC3 cells, according to Annexin V/PI staining and Western blot analysis. These results indicate that MHY219 is a potent HDAC inhibitor that targets regulating multiple aspects of cancer cell death and might have preclinical value in human prostate cancer chemotherapy, warranting further investigation.
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Layer-by-layer assembled PVA/Laponite multilayer free-standing films and their mechanical and thermal properties.
Nanotechnology
PUBLISHED: 10-21-2011
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Structural arrangements of nanoplatelets in a polymer matrix play an important role in determining their properties. In the present study, multilayered composite films of poly(vinyl alcohol) (PVA) with Laponite clay are assembled by layer-by-layer (LBL) deposition. The LBL films are found to be hydrated, flexible and transparent. A facile and solvent-free method-by depositing self-assembled monolayers (SMA) of a functional silane on substrates-is demonstrated for preparing free-standing LBL films. Evolution of nanostructures in LBL films is correlated with thermal and mechanical properties. A well-dispersed solvent-cast PVA/Laponite composite film is also studied for comparison. We found that structurally ordered LBL films with an intercalated nanoclay system exhibits tensile strength, modulus and toughness, which are significantly higher than that of the conventional nanocomposites with well-dispersed clay particles and that of pure PVA. This indicates that clay platelets are oriented in the applied stress direction, leading to efficient interfacial stress transfer. In addition, various grades of composite LBL films are prepared by chemical crosslinking and their mechanical properties are assessed. On account of these excellent properties, the LBL films may find potential use as optical and structural elements, and as humidity sensors.
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Robust color texture features under varying illumination conditions.
IEEE Trans Syst Man Cybern B Cybern
PUBLISHED: 09-26-2011
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Under varying illumination, both the statistical and structural contents of color texture are modified, leading to changes in the observed texture surface. We model the effect of illumination as a perturbation on an ideal color texture and show that the spectra of the ambient light have a significant impact on the observed texture patterns in the individual color channels. Motivated by studies in human color constancy, we propose a correlation-based transformation that minimizes the effect of illumination variation in color texture analysis. Experimental results are included, which validate the performance of the proposed minvariance model in the analysis of color texture.
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Extending anatomic barriers to right laparoscopic live donor nephrectomy.
Urology
PUBLISHED: 06-14-2011
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To analyze the effects of a right-sided-complex laparoscopic live donor nephrectomy, defined as bifurcation of the right renal artery behind the inferior vena cava. Right-sided laparoscopic live donor nephrectomy is now a widely accepted procedure when complex anatomy is encountered on the left.
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A nodulo-cystic eumycetoma caused by Pyrenochaeta romeroi in a renal transplant recipient: A case report.
J Med Case Rep
PUBLISHED: 04-24-2011
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Pyrenochaeta romeroi (P. romeroi) is a saprophytic fungus found in soil and plants. The fungal spores can be introduced into deeper tissues by trauma. It causes eumycetoma, which affects skin and subcutaneous tissues.
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A novel epoxypropoxy flavonoid derivative and topoisomerase II inhibitor, MHY336, induces apoptosis in prostate cancer cells.
Eur. J. Pharmacol.
PUBLISHED: 02-07-2011
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Here, we reported the synthesis of a novel topoisomerase II inhibitor, MHY336, which that has strong topoisomerase-mediated anticancer activity but fewer side effects than other topoisomerase II inhibitors. The catalytic activity of MHY336 on the topoisomerase II enzyme was the same as that of the etoposide. In a cell-free system, MHY336 exhibited a potent activity on scavenging of reactive oxygen species against 3-morpholinosydnonimine hydrochloride (SIN-1)-induced oxidative stress. An in vitro cell-based assay demonstrated that MHY336 significantly inhibited the proliferation of three prostate cancer cell lines, LNCaP, PC-3, and DU145 cells. Notably, the cytotoxicity of MHY336 was more potent in LNCaP cells (IC(50)=1.39 ?M) than in DU145 (IC(50)=2.94 ?M) and PC3 cells (IC(50)=3.72 ?M). Furthermore, MHY336 treatment induced similar levels of cytotoxicity compared to doxorubicin treatment (IC(50)=1.55 ?M) in LNCap cells. Also, MHY336 significantly down-regulated topoisomerase II alpha expression and up-regulated p53 expression in LNCaP cells (wild-type p53), whereas it up-regulated the topoisomerase II alpha protein in both DU145 and PC3 cells (p53 mutated or deleted). MHY336 induced G2/M or S phase arrest in LNCaP cells through a well-documented topoisomerase II-dependent mechanism. Further studies using Annexin V-FITC binding assay, DAPI staining, and Western blot analyses illustrated that MHY336 markedly induced apoptotic cell death via the mitochondria-mediated intrinsic pathway in LNCaP cells. These results suggest that MHY336 is an attractive chemotherapeutic agent because of its topoisomerase II-mediated anti-tumour activity in human prostate cancer.
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Molecular docking studies and in vitro screening of new dihydropyridine derivatives as human MRP1 inhibitors.
Bioorg. Med. Chem.
PUBLISHED: 01-27-2011
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The overexpression of multidrug resistance protein 1 (MRP1) by tumor cells results in multidrug resistance (MDR) to structurally unrelated anticancer drugs. Circumvention of MDR by combination of chemosensitizers with antitumor compounds is a new field of investigation in cancer chemotherapy. Much effort has been put-in recently to identify the modulators/inhibitors of MRP1 to overcome the MDR. 1,4-Dihydropyridine (DHP) derivatives are indicated to be a new class of MRP1 inhibitors in cancer treatment. Molecular docking studies were carried out on 48 newly synthesized DHP derivatives with the crystal structure of MRP1 to gain some structural insights on the binding mode and possible interactions with the active site of MRP1 (NBD1). The 10 top-ranked molecules were selectively evaluated, experimentally for their MRP1 inhibitory effect using the insect cell membrane MRP1 ATPase assay. The inhibitory capacity (IC(50) concentrations) of the test compounds was compared with the reported IC(50)- or the K(i)-concentrations for benzbromarone, a standard MRP1 inhibitor. Amongst the compounds tested, compounds IA(1) and IIA(5) were found to exhibit a potent MRP1 inhibitory action with IC(50) values of 20±4 and 14±2 ?M (mean±SD), respectively as compared to benzbromarone (IC(50)=4 ?M). The compound IIA(5), in particular was found to be more potent than IA(1) in accordance with the docking results. These new DHP derivatives possess promising characteristics for their development as MDR reversal agents.
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Sudden loss of vision in a patient with significant ipsilateral internal carotid disease.
BMJ Case Rep
PUBLISHED: 01-01-2011
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A 74-year-old man developed sudden onset of painless persistent partial loss of vision in the right eye 3 days after right total knee replacement. The initial investigation was for amaurosis fugax with a normal CT scan of the brain but the carotid Doppler confirmed >90% stenosis of the right internal carotid artery. Urgent ophthalmological review confirmed anterior ischaemic optic neuropathy. Subsequently, he lost his vision completely in the right eye. He had a previous high risk hemispheric transient ischaemic attack with carotid Doppler reported as normal.
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Comparison of texture analysis schemes under nonideal conditions.
IEEE Trans Image Process
PUBLISHED: 12-23-2010
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Several recent advancements in the field of texture analysis prompt some fundamental questions. For instance, what is the true impact of these novel advancements under real-world environments? When do these novel advancements fail to perform? Which methods perform better and under what conditions? In this work, we investigate these and other issues under nonideal image acquisition environments, specifically, environments with changing conditions due to illumination variations and those caused by both affine and nonaffine transformations. We study the performance of nine popular texture analysis algorithms using three different datasets, with varying levels of difficulty. Experiments are performed on nonideal texture datasets under five different setups. We find that most state-of-the-art techniques do not perform well under these conditions. To a large extent, their performance under nonideal conditions depends critically on the nature of the textural surface. Moreover, most techniques fail to perform reliably when the number of classes in the dataset is increased significantly, over the regular-size datasets used in previous work. Multiscale features performed reasonably well against variations caused by illumination and rotation but are prone to fail under changes in scale. Surprisingly, the performance for most of the algorithms is generally stable on structured or periodic textures, even with variations in illumination or affine transformations.
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The role of presynaptic dynamics in processing of natural spike trains in hippocampal synapses.
J. Neurosci.
PUBLISHED: 11-26-2010
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Short-term plasticity (STP) represents a key neuronal mechanism of information processing. In excitatory hippocampal synapses, STP serves as a high-pass filter optimized for the transmission of information-carrying place-field discharges. This STP filter enables synapses to perform a highly nonlinear, switch-like operation permitting the passage and amplification of signals with place-field-like characteristics. Because of the complexity of interactions among STP processes, the synaptic mechanisms underlying this filtering paradigm remain poorly understood. Here, we describe a simple mechanistic model of STP, derived in large part from basic principles of synaptic function, that reproduces this highly nonlinear synaptic behavior. The model, formulated in terms of release probability, considers the interactions between calcium-dependent forms of presynaptic enhancement and their impact on vesicle pool dynamics, which is described using a two-pool model of vesicle recruitment. By considering the interdependency between release probability and various forms of STP, the model attempts to provide a realistic coupling among major presynaptic processes. The model parameters are first determined using synaptic dynamics during constant-frequency stimulation. The model then accurately reproduces all major characteristics of the synaptic filtering paradigm during natural stimulus patterns without free parameters. An elimination approach is then used to identify the contribution of each STP component to synaptic dynamics. Based on this analysis, the model predicts strong calcium dependence of synaptic filtering properties, which is verified experimentally in rat hippocampal slices. This simple model may thus offer a useful framework to further investigate the role of STP in neural computations.
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Synthesis, antimicrobial evaluation, and docking studies of novel 4-substituted quinazoline derivatives as DNA-gyrase inhibitors.
Arch. Pharm. (Weinheim)
PUBLISHED: 10-14-2010
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Quinazoline derivatives are reported to have anti-inflammatory, analgesic, antibacterial, and anticancer activities. The incorporation of "OCH?CONH?" (oxymethylcarbamide) at 4th position of the quinazoline ring was found to influence the biological activities of the molecules. With this rationale, some new oxadiazolyl methyloxy quinazolines, pyrazolyl acetoxy methyl quinazolines, triazolylmethyloxy quinazolines were synthesized from anthranilic acid through quinazolyl oxyacetylhydrazide intermediates. All the compounds were characterized by IR, ¹H-NMR, EI-MS, and C, H, N analyses and evaluated for their antimicrobial activity. Docking studies on the DNA-gyrase enzyme (1KZN) show their role in the antimicrobial activity of the molecules and explain the higher potency of compounds 6a, 6b, 8a, 8b based on ReRanking scores and binding poses of the molecules.
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Electrocatalysis and simultaneous determination of catechol and quinol by poly(malachite green) coated multiwalled carbon nanotube film.
Anal. Biochem.
PUBLISHED: 10-04-2010
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Electrochemically active composite film that contains multiwalled carbon nanotubes (MWCNTs), Nafion (NF), and poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold, and indium tin oxide (ITO) electrodes by potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-NF-PMG) enhances the surface coverage concentration (?) of PMG by fivefold. Similarly, an electrochemical quartz crystal microbalance study revealed enhancement in the deposition of PMG at MWCNT-NF film when compared with bare and only NF modified electrodes. The surface morphology of the composite film was studied using atomic force microscopy, which revealed that the PMG incorporated on MWCNT-NF film. The composite film exhibited enhanced electrocatalytic activity toward the mixture of biochemical compounds catechol and quinol. The electrocatalytic responses of analytes at MWCNT-NF-PMG composite film were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electrocatalysis studies, well-separated voltammetric peaks were obtained at the composite film for catechol and quinol with a peak separation of 147mV. The sensitivity values of the composite film toward catechol and quinol by the DPV technique were 0.4 and 3.2mAmM(-1)cm(-2), respectively, which are higher than the values obtained by the CV technique. Similarly, the above-mentioned values are better than the previously reported electroanalytical values for the same analytes.
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Toluidine blue adsorbed on alcohol dehydrogenase modified glassy carbon electrode for voltammetric determination of ethanol.
Talanta
PUBLISHED: 08-26-2010
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A novel toluidine blue O (TBO) adsorbed alcohol dehydrogenase (ADH) biocomposite film have been prepared through simple adsorption technique with the help of electrostatic interaction between oppositely charged layers. Nafion (NF) coating was made on top of the biocomposite film modified glassy carbon electrode (GCE) to protect ADH from leaching. The fabricated ADH/TBO/NF biocomposite electrode remains highly stable in the pH range from 4 to 13. More facile electron transfer process occurs at ADH/TBO/NF biocomposite than at TBO/NF film, which is obvious from the six folds increase in k(s) value. Maximum surface coverage concentration (?) of TBO is noticed at ADH/TBO/NF film, which is 82% higher than at TBO/NF and 15% higher than at ADH/TBO film modified GCEs. Electrochemical impedance spectroscopy studies reveal that ADH has been well immobilized in the biocomposite film. Scanning electron microscopy studies confirm the discriminate surface morphology of various components present in the biocomposite film. Cyclic voltammetry studies validate that ADH/TBO/NF biocomposite film exhibits excellent electrocatalytic activity for ethanol oxidation at low over potential (I(pa)=-0.14 V). The same studies show biocomposite film possesses a good sensitivity of 7.91 ?AM(-1)cm(-2) for ethanol determination. This above sensitivity value is 17.40% higher than the sensitivity obtained for TBO/NF film (6.74 ?AM(-1)cm(-2)). Further, using differential pulse voltammetry, a sensitivity of 1.70 ?AM(-1)cm(-2) has been achieved for ADH/TBO/NF biocomposite film.
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Vitamin B(12) incorporated with multiwalled carbon nanotube composite film for the determination of hydrazine.
Anal. Biochem.
PUBLISHED: 07-16-2010
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Electrochemically active composite film containing multiwalled carbon nanotubes (MWCNTs) and vitamin B(12) was synthesized on glassy carbon, gold, and indium tin oxide electrodes by the potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-B(12)) modified electrode mediates vitamin B(12)s redox reaction, whereas vitamin B(12)s redox reaction does not occur at bare electrode. The electrochemical impedance spectroscopy studies reveal that MWCNTs present in MWCNT-B(12) film enhance electron shuttling between the reactant and electrode surface. The surface morphology of bare electrode, MWCNT film. and MWCNT-B(12) composite film was studied using atomic force microscopy, which reveals vitamin B(12) incorporated with MWCNTs. The MWCNT-B(12) composite film exhibits promising enhanced electrocatalysis toward hydrazine. The electrocatalysis response of hydrazine at MWCNT film and MWCNT-B(12) composite film was measured using cyclic voltammetry and amperometric current-time (i-t) curve techniques. The linear concentration range of hydrazine obtained at MWCNT-B(12) composite film using the i-t curve technique is 2.0 ?M-1.95 mM. Similarly, the sensitivity of MWCNT-B(12) composite film for hydrazine determination using the i-t curve technique is 1.32 mA mM(-1)cm(-2), and the hydrazines limit of detection at MWCNT-B(12) composite film is 0.7 ?M.
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Remodeling of protein and mRNA expression in Leishmania mexicana induced by deletion of glucose transporter genes.
Mol. Biochem. Parasitol.
PUBLISHED: 07-09-2010
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Glucose is a major nutrient in the insect vector stage of Leishmania parasites. Glucose transporter null mutants of Leishmania mexicana exhibit profound phenotypic changes in both insect stage promastigotes and mammalian host stage amastigotes that reside within phagolysosomes of host macrophages. Some of these phenotypic changes could be either mediated or attenuated by changes in gene expression that accompany deletion of the glucose transporter genes. To search for changes in protein expression, the profile of proteins detected on two-dimensional gels was compared for wild type and glucose transporter null mutant promastigotes. A total of 50 spots whose intensities changed significantly and consistently in multiple experiments were detected, suggesting that a cohort of proteins is altered in expression levels in the null mutant parasites. Following identification of proteins by mass spectrometry, 3 such regulated proteins were chosen for more detailed analysis: mitochondrial aldehyde dehydrogenase, ribokinase, and hexokinase. Immunoblots employing antisera against these enzymes confirmed that their levels were upregulated, both in glucose transporter null mutants and in wild type parasites starved for glucose. Quantitative reverse transcriptase PCR (qRT-PCR) revealed that the levels of mRNAs encoding these enzymes were also enhanced. Global expression profiling using microarrays revealed a limited number of additional changes, although the sensitivity of the microarrays to detect modest changes in amplitude was less than that of two-dimensional gels. Hence, there is likely to be a network of proteins whose expression levels are altered by genetic ablation of glucose transporters, and much of this regulation may be reflected by changes in the levels of the cognate mRNAs. Some of these changes in protein expression may reflect an adaptive response of the parasites to limitation of glucose.
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Synthesis, antimicrobial and anticancer activity of new thiosemicarbazone derivatives.
Arch. Pharm. (Weinheim)
PUBLISHED: 07-08-2010
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Thiosemicarbazones of p-aminobenzoic acid (PABA) were synthesized and tested for their antimicrobial and anticancer activity. Hydroxamate derivatives 4a-4l were found to have better antimicrobial and anticancer activity than their acid counterpart. Compound 4d was found to have good antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Vibrio cholerae, and Bacillus subtilis with IC(50) value of about 1 µM. Compound 4f showed potent antifungal activity against Candida albicans (IC(50) ?= 1.29 µM) and compound 4h showed potent anticancer activity (IC(50) ?= 0.07 µM).
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Functionalized multi walled carbon nanotubes nano biocomposite film for the amperometric detection of L-cysteine.
J Nanosci Nanotechnol
PUBLISHED: 04-01-2010
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The development of nano biocomposite film (f-MWCNTs-Au-GO(x)) for L-cysteine (LC) detection is proposed by using glassy carbon electrode (GCE). The proposed nano biocomposite film has been fabricated on ITO for scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. Next, the f-MWCNTs-Au-GO(x) nano biocomposite film modified GCEs surface was examined by scanning electrochemical microscopy (SECM). The proposed nano biocomposite film has been successfully applied for the detection of LC using cyclic voltammetry (CV) and amperometry. The f-MWCNTs-Au-GO(x) film modified GCE exhibited a linear response for LC detection in the lower and higher concentrations ranges of 2 to 42 x 10(-6), 0.1 to 1.08 x 10(-3) mol L(-1). Also, the proposed nano biocomposite film possesses high sensitivity and good repeatability for LC detection.
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Development of selective and reversible pyrazoline based MAO-A inhibitors: Synthesis, biological evaluation and docking studies.
Bioorg. Med. Chem.
PUBLISHED: 01-15-2010
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3,5-Diaryl pyrazolines analogs were synthesized and evaluated for their monoamine oxidase (MAO) inhibitory activity. The compounds were found reversible and selective towards MAO-A with selectivity index in the magnitude of 10(3)-10(5). The docking studies were carried out to gain further structural insights of the binding mode and possible interactions with the active site of MAO-A. Interestingly, the theoretical (K(i)) values obtained by molecular docking studies were in congruence with their experimental (K(i)) values.
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Structural requirements for PACSIN/Syndapin operation during zebrafish embryonic notochord development.
PLoS ONE
PUBLISHED: 09-17-2009
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PACSIN/Syndapin proteins are membrane-active scaffolds that participate in endocytosis. The structure of the Drosophila Syndapin N-terminal EFC domain reveals a crescent shaped antiparallel dimer with a high affinity for phosphoinositides and a unique membrane-inserting prong upon the concave surface. Combined structural, biochemical and reverse genetic approaches in zebrafish define an important role for Syndapin orthologue, Pacsin3, in the early formation of the notochord during embryonic development. In pacsin3-morphant embryos, midline convergence of notochord precursors is defective as axial mesodermal cells fail to polarize, migrate and differentiate properly. The pacsin3 morphant phenotype of a stunted body axis and contorted trunk is rescued by ectopic expression of Drosophila Syndapin, and depends critically on both the prong that protrudes from the surface of the bowed Syndapin EFC domain and the ability of the antiparallel dimer to bind tightly to phosphoinositides. Our data confirm linkage between directional migration, endocytosis and cell specification during embryonic morphogenesis and highlight a key role for Pacsin3 in this coupling in the notochord.
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Molecular cloning, over expression, and activity studies of a peptidic HIV-1 protease inhibitor: designed synthetic gene to functional recombinant peptide.
Peptides
PUBLISHED: 07-24-2009
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The aspartic protease inhibitor (ATBI) purified from a Bacillus sp. is a potent inhibitor of several proteases including recombinant HIV-1 protease, pepsin, and fungal aspartic protease. In this study, we report the cloning, and over expression of a synthetic gene coding for ATBI in Escherichia coli and establish a purification protocol. The ATBI molecule consists of eleven amino acids and is peptidic in nature. We used the peptide sequence data of ATBI to synthesize complementary oligonucleotides, which were annealed and subsequently cloned in-frame with the gene for glutathione-S-transferase (GST). The expression of the resulting fusion protein was induced in E. coli BL21-A1 cells using arabinose. The recombinant peptide was purified using a reduced glutathione column, and cleaved with Factor Xa to remove the GST tag. The resultant product was further purified to homogeneity using RP-HPLC. Mass spectroscopy analysis revealed that the purified peptide had a molecular weight of 1186Da which matches the theoretical molecular weight of the amino acids present in the synthetic gene. The recombinant peptide was found to be active in vitro against HIV-1 protease, pepsin, and fungal aspartic protease. The protocol described in this study may be used to clone pharmaceutically important peptide molecules.
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Nanomaterials - acetylcholinesterase enzyme matrices for organophosphorus pesticides electrochemical sensors: a review.
Sensors (Basel)
PUBLISHED: 04-15-2009
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Acetylcholinesterase (AChE) is an important cholinesterase enzyme present in the synaptic clefts of living organisms. It maintains the levels of the neurotransmitter acetylcholine by catalyzing the hydrolysis reaction of acetylcholine to thiocholine. This catalytic activity of AChE is drastically inhibited by trace amounts of organophosphorus (OP) pesticides present in the environment. As a result, effective monitoring of OP pesticides in the environment is very desirable and has been done successfully in recent years with the use of nanomaterial-based AChE sensors. In such sensors, the enzyme AChE has been immobilized onto nanomaterials like multiwalled carbon nanotubes, gold nanoparticles, zirconia nanoparticles, cadmium sulphide nano particles or quantum dots. These nanomaterial matrices promote significant enhancements of OP pesticide determinations, with the thiocholine oxidation occurring at much lower oxidation potentials. Moreover, nanomaterial-based AChE sensors with rapid response, increased operational and long storage stability are extremely well suited for OP pesticide determination over a wide concentration range. In this review, the unique advantages of using nanomaterials as AChE immobilization matrices are discussed. Further, detection limits, sensitivities and correlation coefficients obtained using various electroanalytical techniques have also been compared with chromatographic techniques.
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Polyaniline and poly(flavin adenine dinucleotide) doped multi-walled carbon nanotubes for p-acetamidophenol sensor.
Talanta
PUBLISHED: 03-07-2009
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A conductive biocomposite film (MWCNTs-PANIFAD) which contains multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(aniline) and poly(flavin adenine dinucleotide) co-polymer (PANIFAD) has been synthesized on gold and screen printed carbon electrodes by potentiostatic methods. The presence of MWCNTs in the MWCNTs-PANIFAD biocomposite film enhances the surface coverage concentration (Gamma) of PANIFAD and increases the electron transfer rate constant (k(s)) to 89%. Electrochemical quartz crystal microbalance studies reveal the enhancements in the functional properties of MWCNTs and PANIFAD present in MWCNTs-PANIFAD biocomposite film. Surface morphology of the biocomposite film has been studied using scanning electron microscopy and atomic force microscopy. The surface morphology results reveal that PANIFAD incorporated on MWCNTs. The MWCNTs-PANIFAD biocomposite film exhibits promising enhanced electrocatalytic activity towards the oxidation of p-acetamidophenol. The cyclic voltammetry has been used for the measurement of electroanalytical properties of p-acetamidophenol by means of PANIFAD, MWCNTs and MWCNTs-PANIFAD biocomposite film modified gold electrodes. The sensitivity value of MWCNTs-PANIFAD film (88.5 mA mM(-1)cm(-2)) is higher than the values which are obtained for PANIFAD (28.7 mA mM(-1)cm(-2)) and MWCNTs films (60.7 mA mM(-1)cm(-2)). Finally, the flow injection analysis (FIA) has been used for the amperometric detection of p-acetamidophenol at MWCNTs-PANIFAD film modified screen printed carbon electrode. The sensitivity value of MWCNTs-PANIFAD film (3.3 mA mM(-1)cm(-2)) in FIA is also higher than the value obtained for MWCNTs film (1.1 mA mM(-1)cm(-2)).
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Multiwalled carbon nanotubes with poly(NDGAChi) biocomposite film for the electrocatalysis of epinephrine and norepinephrine.
Anal. Biochem.
PUBLISHED: 02-19-2009
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A novel biocomposite film (MWCNTs-PNDGAChi), which contains multiwalled carbon nanotubes (MWCNTs) along with the incorporation of poly(nordihydroguaiaretic acid) and chitosan copolymer (PNDGAChi), has been synthesized on gold electrode by potentiostatic methods. The presence of MWCNTs in the biocomposite film enhances PNDGAChis surface coverage concentration (Gamma) on the electrode and decreases degradation of PNDGAChi during cycling. The biocomposite film also exhibits promising enhanced electrocatalytic activity toward the oxidation of biochemical compounds such as epinephrine (EP) and norepinephrine (NEP). Cyclic voltammetry was used for the measurement of electroanalytical properties of analytes by means of MWCNTs-PNDGAChi biocomposite film modified gold electrode. The sensitivity values of MWCNTs-PNDGAChi biocomposite film modified gold electrode are higher than the values obtained for PNDGAChi film modified gold electrode. Electrochemical quartz crystal microbalance studies reveal the enhancements in the functional properties of MWCNTs and PNDGAChi present in MWCNTs-PNDGAChi biocomposite film. Surface morphology of the biocomposite films was studied using scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy. The surface morphology results reveal that PNDGAChi incorporated on MWCNTs. Finally, flow injection analysis was used for the amperometric detection of EP and NEP at MWCNTs-PNDGAChi film modified screen printed carbon electrode.
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Simultaneous determination of adenine guanine and thymine at multi-walled carbon nanotubes incorporated with poly(new fuchsin) composite film.
Anal. Chim. Acta
PUBLISHED: 01-22-2009
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A composite film (MWCNTs-PNF) which contains multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(new fuchsin) (PNF) has been synthesized on glassy carbon electrode (GCE), gold (Au) and indium tin oxide (ITO) by potentiostatic methods. The presence of MWCNTs in the composite film enhances surface coverage concentration (Gamma) of PNF to approximately 176.5%, and increases the electron transfer rate constant (k(s)) to approximately 346%. The composite film also exhibits promising enhanced electrocatalytic activity towards the mixture of biochemical compounds such as adenine (AD), guanine (GU) and thymine (THY). The surface morphology of the composite film deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. These two techniques reveal that the PNF incorporated on MWCNTs. Electrochemical quartz crystal microbalance study reveals the enhancement in the functional properties of MWCNTs and PNF. The electrocatalytic responses of analytes at MWCNTs and MWCNTs-PNF films were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electrocatalysis studies, well separated voltammetric peaks have been obtained at the composite film for AD, GU and THY, with the peak separation of 320.3 and 132.7mV between GU-AD and AD-THY respectively. The sensitivity of the composite film towards AD, GU and THY in DPV technique is 218.18, 12.62 and 78.22mAM(-1)cm(-2) respectively, which are higher than MWCNTs film. Further, electroanalytical studies of AD, GU and THY present in single-strand deoxyribonucleic acid (ssDNA) have been carried out using semi-derivative CV and DPV.
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Haemoglobin immobilized on nafion modified multi-walled carbon nanotubes for O2, H2O2 and CCl3COOH sensors.
Talanta
PUBLISHED: 01-20-2009
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A conductive biocomposite film (MWCNTs-NF-Hb) containing multi-walled carbon nanotubes (MWCNTs) incorporated with entrapped haemoglobin (Hb) in nafion (NF) has been synthesized on glassy carbon electrode (GCE), gold (Au), indium tin oxide (ITO) and screen printed carbon electrode (SPCE) separately by potentiostatic methods. The presence of both MWCNTs and NF in the biocomposite film enhances the surface coverage concentration (Gamma), and increases the electron transfer rate constant (K(s)) to 132%. The biocomposite film exhibits a promising enhanced electrocatalytic activity towards the reduction of O(2), H(2)O(2) and CCl(3)COOH. The cyclic voltammetry has been used for the measurement of electrocatalysis results of analytes by means of biocomposite film-modified GCEs. The MWCNTs-NF-Hb-modified GCEs sensitivity values are higher than the values obtained for other film modified GCEs. The surface morphology of the biocomposite films which have been deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. The studies have revealed that there was an incorporation of NF and immobilization of Hb on MWCNTs. Finally, the flow injection analysis has been used for the amperometric studies of analytes at MWCNTs-Hb and MWCNTs-NF-Hb film modified SPCEs. The amperometric study results have shown higher slope values for MWCNTs-NF-Hb biocomposite film.
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A review on direct electrochemistry of catalase for electrochemical sensors.
Sensors (Basel)
PUBLISHED: 01-20-2009
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Catalase (CAT) is a heme enzyme with a Fe((III/II)) prosthetic group at its redox centre. CAT is present in almost all aerobic living organisms, where it catalyzes the disproportionation of H(2)O(2) into oxygen and water without forming free radicals. In order to study this catalytic mechanism in detail, the direct electrochemistry of CAT has been investigated at various modified electrode surfaces with and without nanomaterials. The results show that CAT immobilized on nanomaterial modified electrodes shows excellent catalytic activity, high sensitivity and the lowest detection limit for H(2)O(2) determination. In the presence of nanomaterials, the direct electron transfer between the heme group of the enzyme and the electrode surface improved significantly. Moreover, the immobilized CAT is highly biocompatible and remains extremely stable within the nanomaterial matrices. This review discusses about the versatile approaches carried out in CAT immobilization for direct electrochemistry and electrochemical sensor development aimed as efficient H(2)O(2) determination. The benefits of immobilizing CAT in nanomaterial matrices have also been highlighted.
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Direct electrochemistry of catalase at multiwalled carbon nanotubes-nafion in presence of needle shaped DDAB for H2O2 sensor.
Talanta
PUBLISHED: 01-15-2009
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The direct electrochemistry of catalase (CAT) at didodecyldimethylammonium bromide (DDAB) present on nafion dispersed multiwalled carbon nanotubes (MWCNTs-NF) modified glassy carbon electrode (GCE) has been reported. The presence of DDAB in MWCNTs-NF-CAT film enhances the surface coverage concentration of CAT (Fe(III/II)) to 48%. Similarly, in presence of DDAB, there is a 57% enhancement in electron transfer rate (ks) with 66% increase in CAT stability. (Fe(III/II)) redox couple exhibits linear dependence with the pH variation (-51 mV pH(-1)). The UV-vis absorption spectroscopy study reveals the entrapped CAT in DDAB film retains its native structure at MWCNTs-NF modified electrodes. Similarly, electrochemical impedance spectroscopy results confirm the co-existence of CAT and DDAB in the modified film. Further, scanning electron microscopy results reveal the structural morphological difference between various components in MWCNTs-NF-(DDAB/CAT) film. The cyclic voltammetry (CV) and amperometry (i-t curve) have been used for the measurement of electroanalytical properties of H2O2 by means of various film modified GCEs. The sensitivity values of MWCNTs-NF-(DDAB/CAT) film for H2O2 using CV (35.62 microA mM(-1)cm2) are higher than the values which are obtained for MWCNTs-NF-CAT film (2.74 mmicroA mM(-1)cm2). Similarly, the sensitivity values using i-t curve are 101.74 microA mM(-1)cm2 for MWCNTs-NF-(DDAB/CAT) and 74.69 microA mM(-1)cm2 for MWCNTs-NF-CAT film. Finally, the diffusion coefficient of H2O2 at MWCNTs-NF-(DDAB/CAT) film (3.4 x 10(-10) cm2 s(-1)) has been calculated using rotating disc electrode studies.
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Automated condition-invariable neurite segmentation and synapse classification using textural analysis-based machine-learning algorithms.
J. Neurosci. Methods
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High-resolution live-cell imaging studies of neuronal structure and function are characterized by large variability in image acquisition conditions due to background and sample variations as well as low signal-to-noise ratio. The lack of automated image analysis tools that can be generalized for varying image acquisition conditions represents one of the main challenges in the field of biomedical image analysis. Specifically, segmentation of the axonal/dendritic arborizations in brightfield or fluorescence imaging studies is extremely labor-intensive and still performed mostly manually. Here we describe a fully automated machine-learning approach based on textural analysis algorithms for segmenting neuronal arborizations in high-resolution brightfield images of live cultured neurons. We compare performance of our algorithm to manual segmentation and show that it combines 90% accuracy, with similarly high levels of specificity and sensitivity. Moreover, the algorithm maintains high performance levels under a wide range of image acquisition conditions indicating that it is largely condition-invariable. We further describe an application of this algorithm to fully automated synapse localization and classification in fluorescence imaging studies based on synaptic activity. Textural analysis-based machine-learning approach thus offers a high performance condition-invariable tool for automated neurite segmentation.
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Evaluation of metabolomic profiling against renal toxicity in Sprague-Dawley rats treated with melamine and cyanuric acid.
Arch. Toxicol.
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Melamine-induced renal toxicity is associated with crystal formation in the kidney following exposure to melamine and cyanuric acid. However, metabolomic profiling of intact kidney tissue after chronic intake of melamine and cyanuric acid (M + CA) mixtures has rarely been studied. The present study investigated the melamine-induced renal toxicity by determining metabolites in the kidney through [(1)H]nuclear magnetic resonance. Melamine (63 mg/kg) and cyanuric acid (6.3 mg/kg) were co-administered to rats via oral gavage for 30 days. The mixture of M + CA (63/6.3 mg/kg) induced nephrotoxicity, as determined by increased blood urea nitrogen (BUN) and creatinine levels. The kidney weights were significantly increased in the animals treated with M + CA (63/6.3 mg/kg). The histological analysis revealed epithelial degeneration and necrotic cell death in the proximal and distal tubules. Furthermore, various metabolites were altered in both renal medullar and cortical tissues. In the medullar tissues, asparagine, choline, creatinine, cysteine, ethanolamine, glucose, isoleucine, glutamine, and myo-inositol levels were elevated, but glucitol, phenylalanine, tyrosine, and sn-glycero-3-levels were reduced. In the cortex, ethanolamine, hypoxanthine, isoleucine and o-phosphoethanolamine levels were increased, whereas formate, glucose, glutathione, threonine, and myo-inositol levels were decreased, suggesting the M + CA-induced renal cell injury. These data suggest that a mixture of M + CA-induced metabolites may be useful biomarkers for the detection of kidney injury.
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A new concept in the sewing rings for mechanical heart valves.
Asian Cardiovasc Thorac Ann
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Valve-associated complications challenge the quality of life and longevity after heart valve replacement. Inappropriate healing may be a contributing factor.
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In silico evaluation of TERT inhibition by anticancer drugs.
J Mol Model
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The activation of telomerase represents an early step in carcinogenesis. Increased telomerase expression in malignant tumors suggests that telomerase inactivation may represent a potential chemotherapeutic target. In this work, existing anticancer drugs were docked against telomerase reverse transcriptase (TERT) using a Lamarckian genetic algorithm (LGA). Autodocks scoring function was applied to each of the molecules in order to identify the inhibitor with the strongest pharmacological action. The structural insights provided by this study regarding binding poses and possible interactions, free energies of binding, and drug scores aided in the identification of potential inhibitory compounds. The ranks of the various ligands investigated were based on the final docked energy values. Among nine selected compounds, vindesine, temsirolimus, and cyclosporine were found to be more potent TERT inhibitors than the standard inhibitor, curcumin.
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Electroanalytical studies on green leaf volatiles for potential sensor development.
Analyst
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An electrochemical study for detecting green leaf plant volatiles from healthy and infected plants has been devised and tested. The electrocatalytic response of plant volatiles at a gold electrode was measured using cyclic voltammetry, amperometric current-time (i-t) analysis, differential pulse voltammetry (DPV) and hydrodynamic experiments. The sensitivity of the gold electrode in i-t analysis was 0.13 mA mM(-1) cm(-2) for cis-3-hexenol, 0.11 mA mM(-1) cm(-2) for cis-hexenyl acetate and 0.02 mA mM(-1) cm(-2) for hexyl acetate. The limits of detection of cis-3-hexenol, cis-hexenyl acetate and hexyl acetate by i-t analysis were 0.5, 0.3 and 0.6 ?M, respectively, at a signal to noise ratio of 3. The hydrodynamic studies yielded the electro-kinetic parameters such as diffusivities of plant volatiles in solution and the rate constants for their electrochemical reactions. The DPV and interference studies reveal that the gold electrode possessed high sensitivity for plant volatiles determination in synthetic samples, which imitates both healthy and infected plants.
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Distinct and separable activities of the endocytic clathrin-coat components Fcho1/2 and AP-2 in developmental patterning.
Nat. Cell Biol.
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Clathrin-mediated endocytosis occurs at multiple independent import sites on the plasma membrane, but how these positions are selected and how different cargo is simultaneously recognized is obscure. FCHO1 and FCHO2 are early-arriving proteins at surface clathrin assemblies and are speculated to act as compulsory coat nucleators, preceding the core clathrin adaptor AP-2. Here, we show that the ?-homology domain of FCHO1/2 represents an endocytic interaction hub. Translational silencing of fcho1 in zebrafish embryos causes strong dorsoventral patterning defects analogous to Bmp signal failure. The Fcho1 ?-homology domain interacts with the Bmp receptor Alk8, uncovering an endocytic component that positively modulates Bmp signal transmission. Still, the fcho1 morphant phenotype is distinct from severe embryonic defects apparent when AP-2 is depleted. Our data thus challenge the primacy of FCHO1/2 in coat initiation.
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