Positive Electrostatic Charge Research Articles

A Common Polymorphism in RNASE6 Impacts Its Antimicrobial Activity toward Uropathogenic Escherichia coli.

Human Ribonuclease (RNase) 6 is a monocyte and macrophage-derived protein with potent antimicrobial activity toward uropathogenic bacteria. The RNASE6 gene is heterogeneous in humans due to the presence of single nucleotide polymorphisms (SNPs). RNASE6 rs1045922 is the most common non-synonymous SNP, resulting in a G to A substitution that determines an arginine (R) to glutamine (Q) transversion at position 66 in the protein sequence. By structural analysis we observed that R66Q substitution significantly reduces the positive electrostatic charge at the protein surface. Here, we generated both recombinant RNase 6-R66 and -Q66 protein variants and determined their antimicrobial activity toward uropathogenic Escherichia coli (UPEC), the most common cause of UTI. We found that the R66 variant, encoded by the major SNP rs1045922 allele, exhibited superior bactericidal activity in comparison to the Q66 variant. The higher bactericidal activity of R66 variant correlated with an increase in the protein lipopolysaccharide binding and bacterial agglutination abilities, while retaining the same enzymatic efficiency. These findings encourage further work to evaluate RNASE6 SNP distribution and its impact in UTI susceptibility.

A human pilot study on positive electrostatic charge effects in solid tumors of the late-stage metastatic patients.

Correlative interactions between electrical charges and cancer cells involve important unknown factors in cancer diagnosis and treatment. We previously reported the intrinsic suppressive effects of pure positive electrostatic charges (PEC) on the proliferation and metabolism of invasive cancer cells without any effect on normal cells in cell lines and animal models. The proposed mechanism was the suppression of pro-caspases 3 and 9 with an increase in Bax/Bcl2 ratio in exposed malignant cells and perturbation induced in the KRAS pathway of malignant cells by electrostatic charges due to the phosphate molecule electrostatic charge as the trigger of the pathway. This study aimed to examine PECs as a complementary treatment for patients with different types of solid metastatic tumors, who showed resistance to chemotherapy and radiotherapy. In this study, solid metastatic tumors of the end-stage patients (n = 41) with various types of cancers were locally exposed to PEC for at least one course of 12 days. The patient's signs and symptoms, the changes in their tumor size, and serum markers were followed up from 30 days before positive electrostatic charge treating (PECT) until 6 months after the study. Entirely, 36 patients completed the related follow-ups. Significant reduction in tumor sizes and cancer-associated enzymes as well as improvement in cancer-related signs and symptoms and patients' lifestyles, without any side effects on other tissues or metabolisms of the body, were observed in more than 80% of the candidates. PECT induced significant cancer remission in combination with other therapies. Therefore, this non-ionizing radiation would be a beneficial complementary therapy, with no observable side effects of ionizing radiotherapy, such as post-radiation inflammation.

Targeted Delivery of Anticancer Drug Loaded Charged PLGA Polymeric Nanoparticles Using Electrostatic Field.

Pure positive electrostatic charges (PPECs) show suppressive effect on the proliferation and metabolism of invasive cancer cells without affecting normal tissues. PPECs are used for the delivery of drug-loaded polymeric nanoparticles (DLNs) capped with negatively charged poly(lactide-co-glycolide) (PLGA) and Poly(vinyl-alcohol) PVA into the tumor site of mouse models. The charged patch is installed on top of the skin in the mouse models'tumor region, and the controlled selective release of the drug is assayed by biochemical, radiological, and histological experiments on both tumorized models and normal rats' livers. It is found that DLNs synthesized by PLGA show great attraction to PPECs due to their stable negative charges, which would not degrade immediately in blood. The burst and drug release after less than 48h of this synthesized DLNs are 10% and 50%, respectively. These compounds can deliver the loaded-drug into the tumor site with the assistance of PPECs, and the targeted-retarded release will take place. Hence, local therapy can be achieved with much lower drug concentration (conventional chemotherapy [2mgkg-1 ] versus DLNs-based chemotherapy [0.75mgkg-1 ]) with negligible side effects in non-targeted organs. PPECs have many potential clinical applications for advanced-targeted chemotherapy with the lowest discernible side effects.

In silico analysis of single nucleotide polymorphism (rs34377097) of TBXA2R gene and pollen induced bronchial asthma susceptibility in West Bengal population, India.

Prevalence of asthma is increasing steadily among general population in developing countries over past two decades. One of the causative agents of broncho-constriction in asthma is thromboxane A2 receptor (TBXA2R). However few studies of TBXA2R polymorphism were performed so far. The present study aimed to assess potential association of TBXA2R rs34377097 polymorphism causing missense substitution of Arginine to Leucine (R60L) among 482 patients diagnosed with pollen-induced asthma and 122 control participants from West Bengal, India. Also we performed in-silico analysis of mutated TBXA2R protein (R60L) using homology modeling. Clinical parameters like Forced expiratory volume in 1 second (FEV1), FEV1/Forced vital capacity (FVC) and Peak expiratory flow rate (PEFR) were assessed using spirometry. Patients' sensitivity was measured by skin prick test (SPT) against 16 pollen allergens. Polymerase chain reaction-based Restriction fragment length polymorphism was done for genotyping. Structural model of wild type and homology model of polymorphic TBXA2R was generated using AlphaFold2 and MODELLER respectively. Electrostatic surface potential was calculated using APBS plugin in PyMol. Genotype frequencies differed significantly between the study groups (P=0.03). There was no significant deviation from Hardy-Weinberg equilibrium in control population (χ2=1.56). Asthmatic patients have significantly higher frequency of rs34377097TT genotype than control subjects (P=0.03). SPT of patients showed maximum sensitivity in A. indica (87.68%) followed by C. nusifera (83.29%) and C. pulcherima (74.94%). Significant difference existed for pollen sensitivity in adolescent and young adult (P=0.01) and between young and old adult (P=0.0003). Significant negative correlation was found between FEV1/FVC ratio and intensity of SPT reactions (P<0.0001). Significant association of FEV1, FEV1/FVC and PEFR was observed with pollen-induced asthma. Furthermore, risk allele T was found to be clinically correlated with lower FEV1/FVC ratio (P=0.015) in patients. Our data showed R60L polymorphism, which was conserved across mammals, significantly reduced positive electrostatic charge of polymorphic protein in cytoplasmic domain thus altered downstream pathway and induced asthma response. The present in-silico study is the first one to report association of TBXA2R rs34377097 polymorphism in an Indian population. It may be used as prognostic marker of clinical response to asthma in West Bengal and possible target of therapeutics in future.

Positive electrostatic therapy of metastatic tumors: selective induction of apoptosis in cancer cells by pure charges.

BackgroundWe discovered that pure positive electrostatic charges (PECs) have an intrinsic suppressive effect on the proliferation and metabolism of invasive cancer cells (cell lines and animal models) without affecting normal tissues.MethodsWe interacted normal and cancer cell lines and animal tumors with PECs by connecting a charged patch to cancer cells and animal tumors. many biochemical, molecular and radiological assays were carried out on PEC treated and control samples.ResultsCorrelative interactions between electrostatic charges and cancer cells contain critical unknown factors that influence cancer diagnosis and treatment. Different types of cell analyses prove PEC‐based apoptosis induction in malignant cell lines. Flowcytometry and viability assay depict selective destructive effects of PEC on malignant breast cancer cells. Additionally, strong patterns of pyknotic apoptosis, as well as downregulation of proliferative‐associated proteins (Ki67, CD31, and HIF‐1α), were observed in histopathological and immunohistochemical patterns of treated mouse malignant tumors, respectively. Quantitative real‐time polymerase chain reaction results demonstrate up/down‐regulated apoptotic/proliferative transcriptomes (P21, P27, P53/CD34, integrin α5, vascular endothelial growth factor, and vascular endothelial growth factor receptor) in treated animal tumors. Expression of propidium iodide in confocal microscopy images of treated malignant tissues was another indication of the destructive effects of PECs on such cells. Significant tumor size reduction and prognosis improvement were seen in over 95% of treated mouse models with no adverse effects on normal tissues.ConclusionWe discovered that pure positive electrostatic charges (PECs) have an intrinsic suppressive effect on the proliferation and metabolism of invasive cancer cells (cell lines and animal models) without affecting normal tissues. The findings were statistically and observationally significant when compared to radio/chemotherapy‐treated mouse models. As a result, this nonionizing radiation may be used as a practical complementary approach with no discernible side effects after passing future human model studies.

Electrification hypothesis of the absence of lice (Anoplura Leach, 1815) on bats (Chiroptera Blumenbach, 1779)

Aim of this work is to substantiate the hypothesis that the absence of lice in bats is associated with the electrification of the surface of their body during the flight.Discussion. The paper analyzes the physical phenomenon of friction electrification, the triboelectric series of substances with special attention to the objects of atmospheric electricity, and the Cohen rule that relates the dielectric properties of a substance to its permittivity. The electrical properties of the atmosphere are described including the occurrence of a potential difference between the Earth's surface and the ionosphere and the mechanism of maintaining this potential as a result of charging the ground with negative electricity by thunderstorms. The results of experimental data on the formation of a positive electrostatic charge on the surface covers of insects and birds are presented. It is hypothesized that the hair and skin membranes of bats should also be positively electrified during flight. The reasons that prevent lice from living in electrified bat hair are described. It is proposed to explain the presence of developed sebaceous glands in bats as a way of discharging electrostatic charge before returning to the shelter and the bell structure of the hair cuticle as a device for retaining the secretion of sweat glands.Conclusion. The absence of lice in bats is a direct consequence of their adaptation to active flight.

Functional and Molecular Basis of Thrombopoietin Receptor Activation By Mutant Calreticulin

▪The thrombopoietin receptor MPL is required for oncogenic transformation by mutant CALR (CALRMUT). We and others have previously shown that CALRMUT binds to the thromobopoietin receptor, MPL, to activate the MPL-JAK-STAT signaling axis, and that the positive charge of the CALRMUT C-terminus is required to mediate this interaction.To provide additional understanding of the mechanism by which CALRMUT is oncogenic, we sought to further resolve which amino acids within the CALRMUT C-terminus are required for CALRMUT to bind MPL, activate MPL signaling, and transform hematopoietic cells. To do this, we generated serial truncations of the mutant C-terminal tail. We found that even the most severely truncated form of the CALRMUT C-terminus retained the ability to bind MPL, but failed to activate JAK-STAT signaling and transform Ba/F3-MPL cells to IL-3 independence. This provides the first evidence that mutant CALR binding to MPL does not uniformly correlate with activation of JAK-STAT signaling and cellular transformation, and suggests a model whereby different thresholds of positive charge in the CALRMUT C-terminus are required to enable binding of CALRMUT to MPL and to activate MPL signaling.We next sought to elucidate the components of MPL that are required to bind CALRMUT and to support oncogenic transformation. We observed that CALRMUT bound to the extracellular domain of MPL, but not the intracellular domain, but that neither domain alone was capable of supporting CALRMUT-associated transformation. We therefore hypothesized that CALRMUT interaction with the MPL extracellular domain still required the intracellular domain of MPL to transmit canonical MPL-associated downstream signaling. We focused on three tyrosine residues within the carboxy-terminal of MPL (Tyr-591, Tyr-626 and Tyr-631), and generated MPL variants where these residues were systematically mutated individually, in tandem, or altogether. We observed no changes in the ability of any of the MPL variants to physically bind to CALRMUT. In contrast, MPL variants harboring mutation of all 3 tyrosine residues were unable to support cytokine-independent growth. Specifically, substitution of Tyr-626 significantly impaired the ability of MPL to support CALRMUT-associated transformation, whereas substitution of Tyr-591/Tyr-31 only had minor effects.Finally, we sought to gain functional insight into how CALRMUT interacts with MPL and how this interaction drives cellular transformation. Wild-type calreticulin is an ER-resident chaperone that interacts with newly synthesized glycoproteins as well as with the polypeptide chain to enable proper protein folding. We created variants of CALRMUT harboring mutations in critical residues implicated in three key functionalities of wild-type CALR - (i) lectin activity, (ii) polypeptide binding and (iii) chaperone activity - and tested their capacity to bind to MPL and confer cytokine-independence. We observed that lectin-deficient CALRMUT were unable to bind to MPL or confer cytokine independence. In contrast, polypeptide binding-deficient variants of CALRMUT retained MPL binding ability and conferred cytokine-independent growth. Finally, we observed that CALRMUT harboring mutations in residues implicated in wild-type CALR chaperone activity retained the ability to physically interact with MPL and confer cytokine-independent growth. Consistent with this, an in vitro binding assay demonstrated that CALRWT exhibits strong, direct binding to the co-chaperone molecule ERp57, whereas CALRMUT does not. Cumulatively, these data suggest that the interaction of CALRMUT with MPL is dependent on the CALRMUT lectin activity but not on its chaperone functionality.In conclusion, our data provide additional insights into the molecular mechanism by which CALRMUT interacts with MPL to induce MPN. Specifically, we uncouple the binding of CALRMUT to MPL from MPL activation and define the key properties of MPL required for CALRMUT binding and for its activation. Together, our findings consolidate the critical role of the positive electrostatic charge of the CALRMUT C-terminus in the oncogenic activity of CALRMUT and suggest a model of transformation whereby CALRMUT acquires a neomorphic function involving pathogenic binding to MPL and possibly to other proteins. DisclosuresNo relevant conflicts of interest to declare.

Capture-free deactivation of CTCs in the bloodstream; a metastasis suppression method by electrostatic stimulation of the peripheral blood

While limited investigations have been reported on CTC elimination and its profits, recently, some new works were reported on detection followed by the destruction of CTCs. Limitations and complications of CTC capturing procedures have highly reduced the chance of selective destruction of CTCs in the bloodstream in the therapeutic guidelines of the patients. Here, we selectively deactivated the invasive function of CTCs during their circulation in the bloodstream by exposing the whole blood to pure positive electrostatic charge stimulation (PPECS). Our treatment suppressed pulmonary metastasis and extended the survival of the mice had been intravenously injected by electrostatically deactivated 4T1 breast cancer CTCs. Moreover, the number of cancerous lung nodules was drastically reduced in the mice injected by treated CTCs in comparison with the non-treated cohort. Evaluating the side effect of the PPECS on the blood components revealed no major effect on the functional properties of the white blood cells, and just a negligible fraction (∼10%) was damaged during this process. This approach does not need any capturing or targeting of CTCs from the blood as it is focused on perturbing the electrical function of negatively-charged tumor cells after being exposed to positive electrostatic charges. Taken together, continuous in-vivo deactivation of CTCs by PPECS with no requirement to complicated capturing protocols may improve the survival of cancer patients.

Influence of zeta potential of ZrO2 and Al2O3 nanoparticles on removal of metal ions by hybrid electrospun polyamide 6 membrane: Kinetics of adsorption and fouling mechanisms

AbstractElectrostatic charging of the adsorbent is a critical method for the selective removal of metal ions fromacidic wastewater. In this study, electrospun polyamide 6 (PA6) membranes were separately incorporated with Al2O3 and ZrO2 nanoparticles (NPs), and their ability in the removal of cations (eg, Al3+ and Fe3+) were evaluated by static adsorption and filtration methods. The impact of various parameters, namely microstructure, surface porosity, functional molecular groups, and hydrophobicity of membranes on the removal process, was investigated. By evaluating the zeta (ζ) potential of oxide ceramic NPs, it was found that the Al2O3 and ZrO2 NPs had positive and negative electrostatic charges inacidic solution, respectively. The results showed that the incorporation of negatively charged ZrO2 NPs improved both the static adsorption and filtration removal capability of the PA6 membrane. The maximum adsorption efficiency of Al3+ and Fe3+ cations was 52.43% and 54.11%, and the highest filtration efficiency of the mentioned cations obtained by electrospun hybrid ZrO2 incorporated PA6 membrane was 98.6% and 99.3%, respectively. It was also found that the adsorption of both Al3+ and Fe3+ cations correlated well with the pseudo‐second‐order kinetic model. The results also demonstrated that the dominant blocking models were switched with the increase in the initial concentration of metal ions from 5 ppm‐70 ppm.

Synthesis of Urease Inhibitory 2, 4-bis (4-cyanobenzyl)glycoluril using Sandmeyer Reaction and Density Functional Theory Investigation

The aim of the present research was to synthesize glycoluril derivative 2,4-Bis(4- cyanobenzyl)glycoluril through a convergent scheme. For this purpose, Sandmeyer reaction procedure was employed for the synthesis of said compound. The structure of the pure compound was confirmed by using different spectroscopic techniques, such as 1HNMR, 13C-NMR and (HR-MS) Mass spectrometry. Convergent synthesis of 2,4-BIS (4-CYANOBENZYL)GLYCOLURIL USING SANDMEYER REACTION and urease inhibition study. The structure of the pure compound was confirmed by using different spectroscopic techniques such as 1H-NMR, 13C-NMR and (HR-MS) Mass spectrometry. The electronic properties of the newly synthesized compound and thiourea were determined by using density functional theory. Furthermore, the compound was evaluated against urease enzyme and was found to be potent inhibitors with an IC50 value of 11.5 ± 1.50 μM when compared with standard inhibitor thiourea (IC50 = 21.0 ± 1.90 μM). The compound may serve as a lead compound to synthesize new cyano-based bambusuril in the future with enhanced biological properties. We have synthesized a new glycoluril derivative 2,4-Bis(4-cyanobenzyl)glycoluril by the sandmeyer reaction. It has been obtained in the form of light yellowish powder in good yield (96%). Glycoluril based macrocycles have been used in various fields; starting from the 2,4-Bis(4-nitrobenzyl)glycoluril (already reported compound), which has undergone reduction (CH3OH,Pt/C) , diazotization (NaNO2/HCl), cyanation (CuCl/KCN), respectively in order to synthesize the desired new glycoluril derivative. The obtained product will be used as a building block for the synthesis of the cyano based bambusuril marcocycle in the future. The yield of the obtained product has been monitored by using different amounts of cyanating reagent, but the best results are shown by the use of 4 mmol of CuCl/KCN. KCN with CuCl assisted the conversion of diazo group into the cyano group with enhanced yield when used in excess amount. It acts as a catalyst. The solubility characteristic of 2,4-Bis(4-cyanobenzyl)glycoluril has also been determined in different organic solvents. 1H NMR technique proved to be very helpful for the structure determination of our desired product. Benzylic protons give signals at 7.5 ppm and 7.8 ppm, respectively. The downfield peaks confirm the presence of CN group near the benzylic protons. Methine protons show a signal at 5.2 ppm, which ensures the basic skeleton of glycoluril. Ureidyl protons also confirm the synthesis of the heterocyclic 2,4-Bis(4-cyanobenzyl)glycoluril compound. The negative and positive electrostatic potential sites, molecular descriptors, and charge density distribution of frontier molecular orbitals are revealing that 4a with promising sites for electrophilic and nucleophilic attacks would result to enhance the urease inhibition, which is in good agreement with the experimental data.

Injectable cationic traps and sticky bacterial emulsifiers: A safe alliance during diesel bioremediation

This study proposes injectable polymeric filters to prevent diesel migration during its bioremediation. Pseudomonas aeruginosa (Gram negative bacterium) was isolated from forest soil and used to biodegrade diesel. P. aeruginosa produced biosurfactants that emulsified diesel in water while degrading it, by decreasing the interfacial tension and forming skins around diesel droplets. In lab experiments, emulsified diesel droplets could migrate through model soil columns (sand and limestone) saturated with water (to mimic aquifers). These results indicate that clean aquifers downstream of diesel spills are at risk of becoming contaminated during diesel bioremediation by P. aeruginosa. Injectable filters were developed to mitigate this risk. Injectable filters were obtained by injecting into model soils aqueous solutions of quaternized hydroxyethylcellulose (HEC+, with a positive electrostatic charge). HEC + adsorbed onto model soils, yielding positively charged surfaces. Diesel droplets stabilized by P. aeruginosa had a negative electrostatic charge (as demonstrated through zeta potential measurements) and adhered onto HEC + coated soil, likely due to attractive electrostatic forces. As a result, diesel droplet mobility through soil columns decreased. Our proof of concept indicates that injectable HEC + filters can protect clean regions of aquifers during the bioremediation of diesel spills by P. aeruginosa.

Complete Prevention of Contact Electrification by Molecular Engineering

Summary Electrostatic charges are easily generated on surfaces during contact electrification. Although these invisible charges have emerged as a new dimension in mediating the functions of surfaces, such as energy conversion, liquid transport, reactivity, and adsorbability, the accumulation of charges on surfaces can also pose many undesirable consequences. Despite notable progress, existing approaches in engineering antistatic surfaces suffer from limitations such as the need to modify bulk materials or for delicate control of patterning on surfaces that rely on the neutralization of generated charges. Herein, we report a general toolbox for designing antistatic coatings by leveraging on chemically heterogeneous components with electron-donating and electron-accepting functions, i.e., N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 1H,1H,2H,2H-perfluorooctyl trimethoxysilane, to molecularly engineer the surface potential to achieve an electrostatic homogeneity and completely prevent charge generation. Our approach is general, which allows the facile fabrication of antistatic coatings on various materials, even flexible and curved, with good re-writability and transparency.

1021 – BIOLOGY AND THERAPEUTIC TARGETING OF MUTANT CALRETICULIN INDUCED MPN

Recurrent mutations in calreticulin (CALR) are present in approximately 20-25% of patients with myeloproliferative neoplasms (MPN). Since its discovery in 2013, we now have a more precise understanding of how mutant CALR, an endoplasmic reticulum chaperone protein, activates the JAK/STAT signaling pathway via a pathogenic binding interaction with the thrombopoietin receptor, MPL, to induce MPN. A series of investigations from several groups, including ours, have since established the biologic requirements for mutant CALR-induced MPN which include: (i) expression of MPL and its N-glycosylation sites (ii) the mutant-specific C-terminus of mutant CALR and in particular its positive electrostatic charge (iii) a physical interaction between mutant CALR and MPL and (iv) the lectin-dependent function of mutant CALR. Building on this work, our group is focused on exploiting the mechanism understanding of mutant CALR-driven MPN for therapeutic gain with a particular focus on identifying and targeting unique molecular dependencies and on immunological approaches. Recurrent mutations in calreticulin (CALR) are present in approximately 20-25% of patients with myeloproliferative neoplasms (MPN). Since its discovery in 2013, we now have a more precise understanding of how mutant CALR, an endoplasmic reticulum chaperone protein, activates the JAK/STAT signaling pathway via a pathogenic binding interaction with the thrombopoietin receptor, MPL, to induce MPN. A series of investigations from several groups, including ours, have since established the biologic requirements for mutant CALR-induced MPN which include: (i) expression of MPL and its N-glycosylation sites (ii) the mutant-specific C-terminus of mutant CALR and in particular its positive electrostatic charge (iii) a physical interaction between mutant CALR and MPL and (iv) the lectin-dependent function of mutant CALR. Building on this work, our group is focused on exploiting the mechanism understanding of mutant CALR-driven MPN for therapeutic gain with a particular focus on identifying and targeting unique molecular dependencies and on immunological approaches.

Targeted Ultrasound Contrast Imaging of Tumor Vasculature With Positively Charged Microbubbles.

Molecular ultrasound imaging of tumor vasculature is being actively investigated with microbubble contrast agents targeted to neovasculature biomarkers. Yet, a universal method of targeting tumor vasculature independent of specific biomarkers, or in their absence, would be desirable. We report the use of electrostatic interaction to achieve adherence of microbubbles to tumor vasculature and resulting tumor delineation by ultrasound imaging. Microbubbles were prepared from decafluorobutane gas by amalgamation of aqueous micellar medium. Distearoyl phosphatidylcholine (DSPC) and polyethylene glycol (PEG)-stearate were used as microbubble shell-forming lipids; cationic lipid distearoyl trimethylammoniumpropane (DSTAP) was included to introduce positive electrostatic charge. Microbubbles were subjected to flotation in normal gravity, to remove larger particles. Murine colon adenocarcinoma tumor (MC38, J. Schlom, National Institutes of Health) was inoculated in the hind leg of C57BL/6 mice. Contrast ultrasound imaging was performed under isoflurane anesthesia, using a clinical imaging system in low power mode, with tissue signal suppression (contrast pulse sequencing, 7 MHz, 1 Hz; Mechanical Index, 0.2). The ultrasound probe was positioned to monitor the tumor and contralateral leg muscle; microbubble contrast signal was monitored for 30 minutes or more, after intravenous bolus administration of 2.10 microbubbles. Individual time point frames were extracted from ultrasound video recording and analyzed with ImageJ. Mean bubble diameter was ~1.6 to 2 μm; 99.9% were less than 5 μm, to prevent blocking blood flow in capillaries. For cationic DSTAP-carrying microbubbles, contrast signal was observed in the tumor beyond 30 minutes after injection. As the fraction of positively charged lipid in the bubble shell was increased, adherent contrast signal in the tumor also increased, but accumulation of DSTAP-microbubbles in the normal muscle increased as well. For bubbles with the highest positive charge tested, DSTAP-DSPC molar ratio 1:4, at 10 minutes after intravenous administration of microbubbles, the contrast signal difference between the tumor and normal muscle was 1.5 (P < 0.005). At 30 minutes, tumor/muscle contrast signal ratio improved and reached 2.1. For the DSTAP-DSPC 1:13 preparation, tumor/muscle signal ratio exceeded 3.6 at 10 minutes and reached 5.4 at 30 minutes. Microbubbles with DSTAP-DSPC ratio 1:22 were optimal for tumor targeting: at 10 minutes, tumor/muscle signal ratio was greater than 7 (P < 0.005); at 30 minutes, greater than 16 (P < 0.01), sufficient for tumor delineation. Cationic microbubbles are easy to prepare. They selectively accumulate in the tumor vasculature after intravenous administration. These microbubbles provide target-to-control contrast ratio that can exceed an order of magnitude. Adherent microbubbles delineate the tumor mass at extended time points, at 30 minutes and beyond. This may allow for an extension of the contrast ultrasound examination time. Overall, positively charged microbubbles could become a universal ultrasound contrast agent for cancer imaging.

Silica xerogels as novel streptomycin delivery platforms

Streptomycin was encapsulated by sol-gel through acid-catalysed (SA) or base-catalysed (SB) gelation processes and the samples were evaluated for their antimicrobial activity against a spectrum of Gram-positive and Gram-negative bacteria. The xerogels were characterized using a set of techniques including N2 adsorption isotherms, SEM, DLS, XRD, FTIR and SAXS to investigate their structure, texture and morphology. Cell viability assay was conducted using MRC5 lung fibroblasts and erythrocytes in order to assess the cytotoxicity of the encapsulated samples. The positive electrostatic charge on the surface was identified as relevant factor for the SA sample, which was shown to be a more effective system than SB sample on inhibiting all bacterial strains tested. The best antimicrobial activity was observed with the encapsulated streptomycin prepared via the acid-catalysed gelation route, showing largest inhibitory zones against Listeria monocytogenes and Staphylococcus aureus. These SA materials caused no cytotoxic effect on mammalian cells.

Modified single point-to-plane corona poling rotating system for production of electret dosimeters

A single point-to-plane corona poling rotating was designed, constructed and well studied for electret production of radiation dosimeters. This innovative system which was patented is based on a new corona charging method which exposes the corona beam towards the surface of a material such as Teflon polytetrafluoroethylene (PTFE). The corona beam from a metal needle automatically scans a defined diameter of the surface of a Teflon PTFE disc placed concentric on a heated rotational metal disc electrode for a certain period of time. Some parameters affecting the uniformity and stability of the deposited charges on the Teflon disc surface include; (a) needle-to-Teflon disc distance, (b) single point-to-plane system modes; modified versus classical, (c) Teflon disc charge polarity, (d) Teflon disc diameter and (e) electret formation process. Large-area (14 cm diameter) Teflon disc electrets (0.2 mm thick) with steady-state negative or positive uniform electrostatic charge potentials up to 1.2 kV with stability up to 77 days studied were produced. The Teflon electret discs produced have high quality with acceptable parameters to be applied for different applications in particular as electret radiation dosimeters. In this paper, the results of parametric studies of the modified corona rotating system are presented, discussed and compared with those of some common corona electret production methods.

Defining the requirements for the pathogenic interaction between mutant calreticulin and MPL in MPN

AbstractMutations in calreticulin (CALR) are phenotypic drivers in the pathogenesis of myeloproliferative neoplasms. Mechanistic studies have demonstrated that mutant CALR binds to the thrombopoietin receptor MPL, and that the positive electrostatic charge of the mutant CALR C terminus is required for mutant CALR-mediated activation of JAK-STAT signaling. Here we demonstrate that although binding between mutant CALR and MPL is required for mutant CALR to transform hematopoietic cells; binding alone is insufficient for cytokine independent growth. We further show that the threshold of positive charge in the mutant CALR C terminus influences both binding of mutant CALR to MPL and activation of MPL signaling. We find that mutant CALR binds to the extracellular domain of MPL and that 3 tyrosine residues within the intracellular domain of MPL are required to activate signaling. With respect to mutant CALR function, we show that its lectin-dependent function is required for binding to MPL and for cytokine independent growth, whereas its chaperone and polypeptide-binding functionalities are dispensable. Together, our findings provide additional insights into the mechanism of the pathogenic mutant CALR-MPL interaction in myeloproliferative neoplasms.

In-situ Transmission Electron Microscopy Study of Oxygen Vacancy Ordering and Dislocation Annihilation in Undoped and Sm-doped CeO2 Ceramics During Redox Processes

Ceria (CeO2) based ceramics have been widely used for many applications due to their unique ionic, electronic, and catalytic properties. Here, we report our findings in investigating into the redox processes of undoped and Sm-doped CeO2 ceramics stimulated by high-energy electron beam irradiation within a transmission electron microscope (TEM). The reduced structure with oxygen vacancy ordering has been identified as the CeO1.68 (C-Ce2O3+δ) phase via high-resolution TEM. The reduction of Ce4+ to Ce3+ has been monitored by electron energy-loss spectroscopy. The decreased electronic conductivity of the Sm-doped CeO2 (Sm0.2Ce0.8O1.9, SDC) is revealed by electron holography, as positive electrostatic charges accumulated at the surfaces of SDC grains under electron beam irradiation, but not at CeO2 grains. The formation of the reduced CeO1.68 domains corresponds to lattice expansion compared to the CeO2 matrix. Therefore, the growth of CeO1.68 nuclei builds up strain inside the matrix, causing annihilation of ...

In-situ transmission electron microscopy study of oxygen vacancy ordering and dislocation annihilation in undoped and Sm-doped CeO2 ceramics during redox processes

Ceria (CeO2) based ceramics have been widely used for many applications due to their unique ionic, electronic, and catalytic properties. Here, we report our findings in investigating into the redox processes of undoped and Sm-doped CeO2 ceramics stimulated by high-energy electron beam irradiation within a transmission electron microscope (TEM). The reduced structure with oxygen vacancy ordering has been identified as the CeO1.68 (C-Ce2O3+δ) phase via high-resolution TEM. The reduction of Ce4+ to Ce3+ has been monitored by electron energy-loss spectroscopy. The decreased electronic conductivity of the Sm-doped CeO2 (Sm0.2Ce0.8O1.9, SDC) is revealed by electron holography, as positive electrostatic charges accumulated at the surfaces of SDC grains under electron beam irradiation, but not at CeO2 grains. The formation of the reduced CeO1.68 domains corresponds to lattice expansion compared to the CeO2 matrix. Therefore, the growth of CeO1.68 nuclei builds up strain inside the matrix, causing annihilation of dislocations inside the grains. By using in-situ high-resolution TEM and a fast OneView camera recording system, we investigated dislocation motion inside both CeO2 and SDC grains under electron beam irradiation. The dislocations prefer to dissociate into Shockley partials bounded by stacking faults. Then, the partials can easily glide in the {111} planes to reach the grain surfaces. Even the Lomer-Cottrell lock can be swept away by the phase change induced strain field. Our results revealed the high mobility of dislocations inside CeO2 and SDC grains during their respective redox processes.

Mutant Calreticulin Requires Both Its Mutant C-terminus and the Thrombopoietin Receptor for Oncogenic Transformation.

Somatic mutations in calreticulin (CALR) are present in approximately 40% of patients with myeloproliferative neoplasms (MPN), but the mechanism by which mutant CALR is oncogenic remains unclear. Here, we demonstrate that expression of mutant CALR alone is sufficient to engender MPN in mice and recapitulates the disease phenotype of patients with CALR-mutant MPN. We further show that the thrombopoietin receptor MPL is required for mutant CALR-driven transformation through JAK-STAT pathway activation, thus rendering mutant CALR-transformed hematopoietic cells sensitive to JAK2 inhibition. Finally, we demonstrate that the oncogenicity of mutant CALR is dependent on the positive electrostatic charge of the C-terminus of the mutant protein, which is necessary for physical interaction between mutant CALR and MPL. Together, our findings elucidate a novel paradigm of cancer pathogenesis and reveal how CALR mutations induce MPN. The mechanism by which CALR mutations induce MPN remains unknown. In this report, we show that the positive charge of the CALR mutant C-terminus is necessary to transform hematopoietic cells by enabling binding between mutant CALR and the thrombopoietin receptor MPL.