NTA Groups Research Articles

Improved diet-based nutritional interventions can improve childhood obesity with the synergistic regulation of gut microbiota.

Childhood obesity is a crucial public health concern worldwide. Dietary intervention is the most common intervention for the treatment of obesity. Therefore, we tested an improved diet-based nutritional interventions to improve the childhood obesity and its gut microbiota. Thirty obese children received a 12-week intervention with the adjust-energy-restricted dietary pattern (A-CRD). Body composition was measured by bioelectrical impedance (Inbody S10) and faecal microbes were profiled by sequencing 16S rRNA. Compared to the NTB group (at 0 week), the NTA group (at 12 weeks) had a significantly greater decrease in body weight, body mass index (BMI) and percent body fat (PBF) ( P < 0.001, respectively), whereas skeletal muscle mass (SMM) and fat free mass (FFM) were not statistically significantly different ( P > 0.05). The gut microbiota was found significantly different between the NTB and NTA groups based on alpha and beta diversity. Bifidobacterium, Blautia, and Streptococcus was significantly increased, whereas Bacteroides and Megamonas was significantly decreased in the NTA group ( P < 0.05, respectively). Meanwhile, NTA group significantly increased the ability to produce short-chain fatty acids (SCFAs; e.g. acetic acid/total dietary energy) and changed he predictive metabolic functional features of the microbiota communities ( P < 0.05, respectively) than the NTB group. In conclusion, A-CRD can significantly improve childhood obesity, and the underlying mechanism may be its effect on gut microbiota and metabolism. Therefore, the diet-based nutrition intervention targeting gut microbiota will be more effective management of body weight and prevention of obesity. Chinese Clinical Trial Register: ChiCTR2300074571.

Hounsfield Unit Assessed Bone Density Amongst Non-Traumatic and Post-Traumatic Arthritic Total Ankle Arthroplasty Patients

Category: Ankle Arthritis; Ankle; Hindfoot; Trauma Introduction/Purpose: The etiology of ankle arthritis is multifactorial and secondary osseous changes to the tibiotalar joint can be variable. The relationship of bone density within the tibia and talus with respect to type of ankle arthritis is not well understood. Improved insight of osseous characteristics amongst ankle arthritis patients is helpful in determining optimal implant selection for total ankle arthroplasty. The purpose of this study is to retrospectively analyze pre-operative total ankle arthroplasty patients' films for osseous characteristics associated traumatic ankle arthritis compared to other forms of arthritis using computed tomography (CT) generated Hounsfield units (HU) to analyze bone mineral density and rate of cyst formation. Methods: A retrospective analysis was performed of 440 patients, under a single orthopedic practice, who underwent primary TAA between 2013-2019. Pre-operative HU of tibia and talus were analyzed amongst two groups (Non-traumatic OA, Post- traumatic OA) within one year prior to TAA. Results: Forty-nine qualified patients (23 NTA, 26 PTA) with mean follow-up in months of 19.98 (SD 15.22) were analyzed. Cystic changes at level of TAA cuts or retained bone: 5 tibia (10.2%), 7 talus (14.29%), 16 combined (32.65%). Overall tibial HU mean 270.23 (SD 91.28) and talus 463.26 (103.65). HU of the tibia amongst post-traumatic and non-traumatic patients was 257.21 (SD 93.9) and 284.94 (SD 87.9) (p=0.29137) and talus 434.53 (104.7) and 495.75 (94.33) (p=0.0365). Conclusion: Our results suggest with tibiotalar arthritis HU is a useful tool to predict bone quality. Clinical results amongst the NTA and PTA groups was comparable. Significantly lower HU values were recorded for the PTA groups. Rate of cystic formation within bone of distal tibia does not necessarily correlate with overall HU measured bone mineral density.

Site-Specific and Covalent Immobilization of His-Tagged Proteins via Surface Vinyl Sulfone-Imidazole Coupling.

Site-specific immobilization of proteins on a surface has been a long-lasting challenge in the fields of biosensing and biotechnology because of the need for improving the biological activity of immobilized protein via the maximal exposure of its bioactive domain. Herein, we reported a new site-specific immobilization method for His-tagged proteins onto a vinyl sulfone (VS)-bearing surface in a covalent manner. X-ray photoelectron spectroscopy characterization indicated the specificity of the addition reaction of the imidazole group in histidine on the VS-bearing surface at pH 7.0. Solution-based experiments were carried out to verify the reaction priority of the imidazole residue of histidine with the VS group at neutral conditions. The real-time immobilization process of two His-tagged proteins (HaloTag-6His and anti-HER2 Fab-6His) on surfaces presenting VS, preactivated carboxyl, and NTA groups were studied by quartz crystal microbalance. Compared to the existing methods utilizing covalent (NHS/EDC activated carboxyl) and coordinate (Ni2+-NTA) linking, our method offers two significant advantages for protein immobilization: high density and high specificity. The orientation of the two His-tagged proteins on the VS-bearing surface was confirmed by an enzyme-linked assay and an HER2+ liposome binding experiment. Our method of site-specific immobilization of His-tagged proteins is efficient and straightforward, which would be helpful to expand the applications of recombinant proteins in enzyme immobilization, biosensor and array fabrication, and drug delivery system.

Space-confined pyrolysis for fabrication of peacods-like Fe3O4@C-Ni nanostructures for catalysis and protein adsorption

A unique nanostructure of Fe3O4 nanoparticles (NPs)-in/carbon layer/out-Ni NPs was developed and proved to be an efficient catalyst and protein adsorbent. This kind of nanostructure was formed through a space-confined pyrolysis procedure using polydopamine-Ni2+ coated Fe-NTA nanowires as the precursor. A N-doped carbon interlayer derived from polydopamine (PDA) supported a large amount of Ni NPs and entrapped well-defined Fe3O4 NPs, which were obtained through reduction of Ni2+, Fe3+ by carbonized NTA groups and a PDA layer. The contributions of the unique configuration along with the high density of Ni NPs in Fe3O4@C-Ni are significant for improving catalysis and protein adsorption performance, which is expected to be a promising alternative to other conventional catalysts and protein adsorbents. Due to the unique novel nanostructure, this nanocomposite possesses a wide range of applications, not only for catalytic reactions but also for other inhomogeneous reactions.

Endogenous Membrane Receptor Labeling by Reactive Cytokines and Growth Factors to Chase Their Dynamics in Live Cells

Summary Cytokine and growth factor receptors localized on cell membranes play key roles in many biological events. Because the dynamic behaviors of receptors are deeply involved in cytokine- and growth-factor-dependent signaling pathways, reliable techniques for real-time imaging of receptors in live cells are strongly desired. Here, we describe a method of covalently labeling and imaging membrane receptors in live cells by using chemically reactive cytokines and growth factors coupled with 4-dimethylaminopyridine (DMAP), an organocatalyst that facilitates acyl transfer. Construction of the DMAP cytokines and growth factors relies on non-covalent coordination chemistry between an oligo-histidine tag and dimeric Ni(II)-nitrilotriacetate in an in situ manner. This supramolecular approach is relatively simple and flexible and can be applied to labeling not only transiently but also endogenously expressed receptors. Moreover, given the benefit of this traceless labeling of the receptors, our technique allows real-time imaging of the ligand-induced dynamics of endogenously expressed receptors in live cells.

Label-free histamine detection with nanofluidic diodes through metal ion displacement mechanism

We design and characterize a nanofluidic device for the label-free specific detection of histamine neurotransmitter based on a metal ion displacement mechanism. The sensor consists of an asymmetric polymer nanopore fabricated via ion track-etching technique. The nanopore sensor surface having metal–nitrilotriacetic (NTA–Ni2+) chelates is obtained by covalent coupling of native carboxylic acid groups with Nα,Nα-bis(carboxymethyl)-l-lysine (BCML), followed by exposure to Ni2+ ion solution. The BCML immobilization and subsequent Ni2+ ion complexation with NTA moieties change the surface charge concentration, which has a significant impact on the current–voltage (I–V) curve after chemical modification of the nanopore. The sensing mechanism is based on the displacement of the metal ion from the NTA–Ni2+ chelates. When the modified pore is exposed to histamine solution, the Ni2+ ion in NTA–Ni2+ chelate recognizes histamine through a metal ion coordination displacement process and formation of stable Ni-histamine complexes, leading to the regeneration of metal-free NTA groups on the pore surface, as shown in the current-voltage characteristics. Nanomolar concentrations of the histamine in the working electrolyte can be detected. On the contrary, other neurotransmitters such as glycine, serotonin, gamma-aminobutyric acid, and dopamine do not provoke significant changes in the nanopore electronic signal due to their inability to displace the metal ion and form a stable complex with Ni2+ ion. The nanofluidic sensor exhibits high sensitivity, specificity and reusability towards histamine detection and can then be used to monitor the concentration of biological important neurotransmitters.

(Keynote) Labeless Photoelectrochemical and Impedimetric Aptasensors and Immunosensors Based on Biofunctionalized Electropolymerized Polymers

For four decades, the development of biointerfaces has been the subject of increasing research efforts in the field of biosensors and energy conversion. Owing to their high conductivity, inertness and electroactive surface area, graphene and carbon nanotube are widely used for the design of biosensors and their functionalization was successfully performed by electrogenerated polymers exhibiting affinity or covalent binding interactions towards biomolecules. Recent examples of electropolymerized films will be presented for the design of labeless immunosensors and aptasensors for bisphenol A, cocaine, dengue antibody or cholera toxin antibody [1]. We report thus the synthesis and electrochemical characterization of a novel electropolymerizable Ru(II) complex bearing an intercalator group as well as the electrochemical behavior and photoelectrochemical properties of the resulting polymer film [2]. The latter was applied to the label-free photoelectrochemical detection of cocaine. A photoelectrode was thus designed by electrodeposition of a pyrrole monomer modified with a polypyridyl Ru(II) complex bearing benzo[i]dipyrido-[3,2-a:2’.3’-c]phenazine (dppn) ligand. Owing to the intercalating properties of these immobilized complexes towards DNA double helix, cocaine aptamer was immobilized on the modified electrodes thanks to its stem-loop configuration in order to design a photoelectrochemical cocaine aptasensor. The detection of cocaine via the formation of the aptamer/cocaine complex was successfully observed via a decrease in the photocurrent intensity. The photoelectrochemical aptasensor exhibits a detection limit of 10 nmol L-1 and linear range of 1 10-8 to 5 10-4 mol L-1 [3]. We report here the original synthesis of an anti-bisphenol A (BPA) aptamer conjugated at its 5’-end with a pentahistidine peptide and its use for the design of an impedimetric BPA aptasensor. The introduction of a histidine tag is dedicated to the non-covalent binding of the aptamer onto electrodes previously modified by polypyrrole nitrilotriacetic films. The aptamer immobilization occurs via the histidine axial ligation onto Cu complex chelated by the polypyrrole film. This immobilization method, already used by our group to elaborate immunosensors or DNA sensors, offers a close proximity at the molecular level between the immobilized probe and the modified electrode surface. This approach thus confers a high sensitivity to the detection process, namely the aptamer/BPA folding. The resulting labeless impedimetric aptasensor displays a wide linear range from 10-11 to 10-6 mol L-1 with a sensitivity of 26 W cm2 per decade and an excellent specificity towards interfering agents such as 4,4'-dihydroxybiphenyl and bisphenol P. With the aim to improve the sensitivity of impedimetric biosensors, we have investigated the influence of a multiwalled carbon nanotube (MWCNT) coating and its thickness on the impedimetric transduction. We present thus a reliable procedure based on dispersion and filtration of MWCNT forming homogeneous films with controlled thicknesses and morphologies, which can easily be transferred on electrode surfaces. Polypyrrole-NTA films were electrogenerated on MWCNT modified glassy carbon electrode to immobilize biotinylated cholera toxin via the coordination of the biotin group onto Cu2+ complex chelated on the polymerized NTA groups. Concerning the design of this immunosensor, different thicknesses of carbon nanotube films were tested. For this purpose, three different volumes of CNT suspension solutions were filtered on a cellulose filter and then transferred to the electrode surface for modification of the three different thickness films by electropolymerization and post-biofunctionalization. The resulting impedimetric immunosensor for cholera toxin antibody, shows excellent reproducibility, increased sensitivities, and an exceptional linear range for antibody detection between 0.1 pg.mL-1 to 1 mg.mL-1. Similar results were obtained for the detection of Dengue antibody, namely a detection limit of 0.1 pg.mL-1. References F. Cecchini, L. Fajs, S. Cosnier, R. S. Marks, Trends in analytical chemistry, in pressF. Haddache, A. Le Goff, B. Reuillard, K. Gorgy, C. Gondran, N. Spinelli, E. Defrancq, S. Cosnier, Chem. Eur. J. 2014, 20, 15555-15560.F. Haddache, A. Le Goff, N. Spinelli, P. Gairola, K. Gorgy, C. Gondran, E. Defrancq, S. Cosnier, Anal. Chem., submitted.

Comparison of Successful Myocardial Reperfusion and Adverse Events in Patients With ST-Elevation Myocardial Infarction Who Underwent Rescue Percutaneous Coronary Intervention After Failed Fibrinolytic Therapy With Versus Without Manual Coronary Thrombus Aspiration

It has been unclear the impact of manual thrombus aspiration (TA) on procedural outcomes in patients with ST-elevation myocardial infarction (STEMI) who underwent rescue percutaneous coronary intervention (PCI) after failed fibrinolytic therapy in comparison with primary PCI. Our aim was to test the hypothesis that manual TA may improve myocardial reperfusion and clinical outcomes in patients with STEMI who underwent rescue PCI after failed fibrinolytic therapy. From March 2011 to March 2014, 70 patients with STEMI after unsuccessful fibrinolysis were randomized to either rescue PCI with TA (TA group) or without TA (NTA group). Primary end points were rate of myocardial blush grade ≥2 and ST-segment resolution ≥70%. The secondary end point included 30days follow-up for major adverse cardiac events (MACEs). Baseline clinical and angiographic characteristics were similar in the 2 groups. The TA and NTA groups were compared as follows: myocardial blush grade ≥2, 71% versus 46% (p <0.05); complete ST-segment resolution 71% versus 46% (p <0.05); no reflow 20% versus 49% (p <0.05); procedure time (min) 65.0 ± 38.6 versus 90.1 ± 28.8 (p <0.05); contrast amount (ml) 99.0 ± 45.2 versus 121.2 ± 33.4 (p <0.05); and direct stenting 60% versus 37% (p <0.05). There was a significant reduction of MACE in the TA group, 20% versus 37% (p <0.05). In conclusion, rescue PCI with manual TA leads to better myocardial reperfusion and significant reduction of MACE.

Localizing chemical groups while imaging single native proteins by high-resolution atomic force microscopy.

Simultaneous high-resolution imaging and localization of chemical interaction sites on single native proteins is a pertinent biophysical, biochemical, and nanotechnological challenge. Such structural mapping and characterization of binding sites is of importance in understanding how proteins interact with their environment and in manipulating such interactions in a plethora of biotechnological applications. Thus far, this challenge remains to be tackled. Here, we introduce force-distance curve-based atomic force microscopy (FD-based AFM) for the high-resolution imaging of SAS-6, a protein that self-assembles into cartwheel-like structures. Using functionalized AFM tips bearing Ni(2+)-N-nitrilotriacetate groups, we locate specific interaction sites on SAS-6 at nanometer resolution and quantify the binding strength of the Ni(2+)-NTA groups to histidine residues. The FD-based AFM approach can readily be applied to image any other native protein and to locate and structurally map histidine residues. Moreover, the surface chemistry used to functionalize the AFM tip can be modified to map other chemical interaction sites.

Akwansisi Cultural Heritage and the Creation of a National Identity: The Cross River Monoliths, Nigeria

In a small region of the Central Cross River, culturally and linguistically designated ‘Bakor’, lie columns of stone carvings (monoliths), in human forms. These carvings are referred to locally as Akwansisi (stones of the departed), by the Nta and Nde groups and Atal (stones), by other Bakor speaking groups. This stone culture stretches to parts of the Benue valley, Boki, Obubra, Ogoja and the Nigerian Cameroun border. The culture zone is historically the homeland of the great Bantu or semi Bantu people of African history. Anthropological and other scholarly surveys by foreign observers and commentators have attributed the origins of the Cross River monoliths to the creative ingenuity of wandering Hamites or alien occupants who are today not within the culture zone. This paper attempts not only to ward off the lingering appendage of Hamitic and outside-in interpretation of internal developments, but to show evidently that the artistic and impressive columns of stone carvings are the handiwork of the ancestors of the present occupants of the region stretching back to antiquity. Akwansisi are a heritage of African arts and culture with historical, religious and social significance to the groups who inhabit the region; they are a symbol of Bakor identity. The paper also decries the abysmal neglect of the nation’s cultural artifacts, antipathy for cultural heritage and the lack of a maintenance attitude even in this age of cultural tourism. LWATI: A Journal of Contemporary Research , 9(2), 81-88, 2012

Development of a Histidine-Targeted Spectrophotometric Sensor Using Ni(II)NTA-Functionalized Au and Ag Nanoparticles

An antibody-free diagnostic reagent has been developed based on the aggregation-induced colorimetric change of Ni(II)NTA-functionalized colloidal gold and silver nanoparticles. This diagnostic strategy utilizes the high binding affinity of histidine-rich proteins with Ni(II)NTA to capture and cross-link the histidine-rich protein mimics with the silver and gold nanoparticles. In model studies, the aggregation behavior of the Ni(II)NTA nanoparticles was tested against synthetic targets including charged poly(amino acid)s (histidine, lysine, arginine, and aspartic acid) and mimics of Plasmodium falciparum histidine-rich protein 2 (pfHRP-II). Aggregation of the nanoparticle sensor was induced by all of the basic poly(amino acid)s including poly(l-histidine) within the pH range (5.5-9.0) tested, which is likely caused by the coordination between the multivalent polymer target and Ni(II)NTA groups on multiple particles. The peptide mimics induced aggregation of the nanoparticles only near their pK(a)'s with higher limits of detection. In addition, monomeric amino acids do not show any aggregation behavior, suggesting that multiple target binding sites are necessary for aggregation. Long-term stability studies showed that gold but not silver nanoparticles remained stable and exhibited similar aggregation behavior after 1 month of storage at room temperature and 37 °C. These results suggest that Ni(II)NTA gold nanoparticles could be further investigated for use as a sensor to detect histidine-rich proteins in biological samples.

Measurement of the mechanical behavior of yeast membrane sensors using single-molecule atomic force microscopy

In Saccharomyces cerevisiae, surface stresses acting on the cell wall or plasma membrane are detected by a group of five membrane sensors: Wsc1, Wsc2, Wsc3, Mid2 and Mtl2. Here we present protocols to measure the mechanical properties of Wsc1 sensors in their native cellular environment, using the combination of genetic manipulations with single-molecule atomic-force microscopy (AFM). We describe procedures (i) for obtaining genetically modified sensors that are fully functional and suitable for AFM analysis, i.e., elongated Wsc1 derivatives terminated with a His-tag, and (ii) for detecting and stretching single Wsc1 sensors on the surface of living S. cerevisiae cells, using AFM tips functionalized with Ni(2+)-NTA groups. These procedures are multidisciplinary to implement and need competent researchers from at least two disciplines: molecular biology and nanotechnology. For experienced researchers in biological AFM, the entire protocol can be completed in approximately 3 weeks.

Label-free detection of cupric ions and histidine-tagged proteins using single poly(pyrrole)-NTA chelator conducting polymer nanotube chemiresistive sensor

Novel chemical and biological sensors based on a single poly(pyrrole)-NTA chelator nanotube for sensitive, selective, rapid and real-time detection of histidine-tagged protein and cupric ions are reported. NTA groups on the nanotube surface provided a simple mechanism for metal ion sensing via the high-affinity interaction between NTA and the subsequent detection of histidine-tagged protein through the coordination with metal chelated nanotube. Poly(pyrrole)-NTA chelator nanotubes of 190 nm outside diameter, 35 nm wall thickness and 30 μm long were synthesized by electrochemical polymerization of pyrrole-NTA inside a 200 nm diameter alumina template and assembled as a chemoresistive device by bottom-up contact geometry on a pair of parallel gold electrodes with a gap distance of 3 μm. The chemoresistive sensors based on single poly(pyrrole)-NTA chelator nanotube exhibited detection as low as one-hundredth attomolar (0.6 ppt) cupric ions and 1 ng/ml of penta-histidine tagged syntaxin protein.

Efeitos do esteróide anabólico nandrolona sobre o músculo sóleo de ratos submetidos a treinamento físico através de natação: estudo histológico, histoquímico e morfométrico

Este estudo teve por objetivo analisar as alterações histológicas, histoquímicas e morfométricas das fibras do músculo sóleo de ratos submetidos a um programa de natação, associado ou não à administração do esteróide anabólico decanoato de nandrolona. Foram utilizados 22 ratos Wistar machos, 12 dos quais receberam injeção intramuscular do esteróide (5mg/kg) e 10, óleo mineral (5mg/kg), duas vezes por semana. Os animais foram submetidos a 42 sessões de natação por nove semanas (de segunda a sexta-feira), com aumento progressivo de carga por meio do tempo de natação. Após o sacrifício, o músculo sóleo esquerdo foi retirado, imerso em n-hexana e acondicionado em nitrogênio líquido. Cortes do terço médio desse músculo foram feitos em micrótomo criostato (-20ºC) e corados pela técnica HE e pelo método histoquímico NADH-TR. Os animais submetidos a treinamento físico e a esteróide (TA) ou óleo mineral (TO) apresentaram fibras musculares com maior diâmetro, quando comparados com os animais-controle (NTA e NTO). Não houve diferença significativa entre as medidas das médias dos diâmetros das fibras dos grupos NTA e NTO e entre TA e TO. Nos grupos TA e NTA notou-se acentuado processo de fagocitose, arredondamento e hialinização das fibras musculares. Já nos grupos TA, TO e NTA observou-se perda da atividade enzimática oxidativa. Os resultados sugerem que a natação produz hipertrofia muscular de forma semelhante, tanto no grupo que recebeu esteróide como no que recebeu óleo mineral. No entanto, o grupo que recebeu esteróide apresentou sinais claros de maior degeneração muscular.

Calcium-ion induced color changes of a porphyrin solution

Interactions between the porphyrin-bearing multidentate ligands and group II metal ions in aqueous solution were studied. Changes in the visible spectra of 5 × 10 −5 M solution of the porphyrin in 0.01 M 2-[4-(2-hydroxyethyl)-1-piperazinyl] ethanesulfonic acid (pH 7.4) containing 0.1 M KCl were observed upon titration of Ca 2+ at 25 °C. From the analyses of NMR and visible spectral data, we proposed that the spectral changes are due to the formation of an associate between the porphyrin and Ca 2+ via the following three interactions: (i) formation of a complex between the attached NTA groups and Ca 2+; (ii) hydrophobic interaction among porphyrin rings; and (iii) interaction between the pyrrole nitrogens and Ca 2+.

NTA-Functionalized Poly(L-lysine)-g-Poly(Ethylene Glycol): A Polymeric Interface for Binding and Studying 6 His-tagged Proteins.

In this paper, a novel graft copolymer, poly-(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) with part of the PEG chains carrying a terminal nitrilotriacetic acid group (NTA) was synthesized. Through electrostatic interactions, these polycationic graft co-polymers assemble spontaneously from aqueous solution onto negatively charged surfaces, forming polymeric monolayers that present NTA groups at controlled surface densities on a highly PEGylated background. The NTA-functionalized PLL-g-PEG surfaces proved to be highly resistant to nonspecific adsorption in contact with human serum while allowing the specific and reversible surface binding of GFPuv-6His and β-lactamase-6His in native conformation. Micropatterns consisting of NTA-functionalized PLL-g-PEG in a background of PLL-g-PEG were produced using the "molecular assembly patterning by lift-off" technique. Exposure to Ni2+and GFPuv-6His resulted in a protein pattern of excellent contrast as judged by fluorescence microscopy. Furthermore, optical waveguide lightmode spectroscopy (OWLS) and a miniature fiber optic absorbance spectrometer (FOAS) were combined as affinity and catalytic biosensor to monitor in situ and quantitatively the amount of immobilized β-lactamase-6His and to determine the activity of the immobilized enzyme. The NTA-functionalized PLL-g-PEG surface is considered to be a promising sensor platform for binding 6 His-tagged proteins thanks to the simplicity and cost-effectiveness of the surface modification protocol, high specificity and nearly quantitative reversibility of the protein binding, and the potential to fabricate microarrays of multiple capture molecules.