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1.
J Sep Sci ; 47(1): e2300719, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38066389

RESUMEN

The electric field (E-field) dielectric polarization-based separations mechanism represents a novel method for separating solutions at small length scales. An E-field gradient with a maximum strength of 0.4 MV/m applied across a 10 µm deep channel is shown to increase the concentration inside the low E-field region by ≈ 40% relative to the high E-field region. This concentration change is two orders of magnitude higher than the estimated change predicted using the classical equilibrium thermodynamics for the same E-field. The deviation between the predicted and the experimental results suggests that the change in volumetric E-field energy with solute concentration is insufficient to explain this phenomenon. The study also explores the effect of varying strength of E-field and frequency of supplied voltage on the dielectric polarization-based separation efficiency. While the increase in the former increases the separation efficiency, the increase in the latter reduces the degree of concentration change due to ineffective charging of the electrodes.

2.
Langmuir ; 38(3): 1204-1214, 2022 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-35029113

RESUMEN

High strength AC electric fields generate a body force on a dielectric medium confined between two electrodes. The body forces are due to two factors. First is the variation in permittivity across an interface such as liquid-air present between the electrodes. The second is a change in the dielectric property of the medium due to a variation in the thermodynamic properties such as temperature. The height rise of a dielectric medium between two electrodes is one of the consequences of these electrical body forces and is used here as a comparatively simple way to study these forces. In an aqueous solution with finite conductivity, the effects of the frequency of the supplied voltage source and the temperature change due to Joule heating on height rise have never been studied in this context. This study focuses on systems where the contributions of surface forces are negligible and highlights the interplay between solution conductivity, applied electric field, and the solution height/temperature behavior. Using a generic thermodynamic model for an aqueous solution under the application of an alternating current electric field, it is shown that for low conductivity solutions the resulting temperature and height rise change weakly with the applied field frequency and strongly with the applied electric field. For higher conductivity solutions, the behavior becomes more complex with respect to the electric field strength. As compared to Pellat's original model, the height rise varies from strongly suppressed to enhanced.

3.
J Infect Dis ; 223(11): 1953-1964, 2021 06 04.
Artículo en Inglés | MEDLINE | ID: mdl-32989463

RESUMEN

BACKGROUND: Targeting multiple key antigens that mediate distinct Plasmodium falciparum erythrocyte invasion pathways is an attractive approach for the development of blood-stage malaria vaccines. However, the challenge is to identify antigen cocktails that elicit potent strain-transcending parasite-neutralizing antibodies efficacious at low immunoglobulin G concentrations feasible to achieve through vaccination. Previous reports have screened inhibitory antibodies primarily against well adapted laboratory parasite clones. However, validation of the parasite-neutralizing efficacy against clinical isolates with minimal in vitro cultivation is equally significant to better ascertain their prospective in vivo potency. METHODS: We evaluated the parasite-neutralizing activity of different antibodies individually and in combinations against laboratory adapted clones and clinical isolates. Clinical isolates were collected from Central India and Mozambique, Africa, and characterized for their invasion properties and genetic diversity of invasion ligands. RESULTS: In our portfolio, we evaluated 25 triple antibody combinations and identified the MSP-Fu+CyRPA+RH5 antibody combination to elicit maximal parasite neutralization against P. falciparum clinical isolates with variable properties that underwent minimal in vitro cultivation. CONCLUSIONS: The MSP-Fu+CyRPA+RH5 combination exhibited highly robust parasite neutralization against P. falciparum clones and clinical isolates, thus substantiating them as promising candidate antigens and establishing a proof of principle for the development of a combinatorial P. falciparum blood-stage malaria vaccine.


Asunto(s)
Antígenos de Protozoos/inmunología , Vacunas contra la Malaria , Malaria Falciparum , Anticuerpos Antiprotozoarios , Eritrocitos/inmunología , Humanos , Vacunas contra la Malaria/inmunología , Malaria Falciparum/prevención & control , Plasmodium falciparum , Estudios Prospectivos , Proteínas Protozoarias/inmunología
4.
PLoS Pathog ; 15(5): e1007789, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-31095644

RESUMEN

The highly conserved proteins of the 14-3-3 family are universal adaptors known to regulate an enormous range of cellular processes in eukaryotes. However, their biological functions remain largely uncharacterized in pathogenic protists comprising of several 14-3-3 protein isoforms. In this study, we report the role of 14-3-3 in coordinating cytoskeletal dynamics during phagocytosis in a professional phagocytic protist Entamoeba histolytica, the etiological agent of human amebiasis. There are three isoforms of 14-3-3 protein in amoeba and here we have investigated Eh14-3-3 Protein 3 (EhP3). Live and fixed cell imaging studies revealed the presence of this protein throughout the parasite phagocytosis process, with high rate of accumulation at the phagocytic cups and closed phagosomes. Conditional suppression of EhP3 expression caused significant defects in phagocytosis accompanied by extensive diminution of F-actin at the site of cup formation. Downregulated cells also exhibited defective recruitment of an F-actin stabilizing protein, EhCoactosin at the phagocytic cups. In addition, mass spectrometry based analysis further revealed a large group of EhP3-associated proteins, many of these proteins are known to regulate cytoskeletal architecture in E histolytica. The dynamics of these proteins may also be controlled by EhP3. Taken together, our findings strongly suggest that EhP3 is a novel and a key regulatory element of actin dynamics and phagocytosis in E. histolytica.


Asunto(s)
Proteínas 14-3-3/metabolismo , Actinas/metabolismo , Citoesqueleto/metabolismo , Entamebiasis/parasitología , Eritrocitos/parasitología , Fagocitosis , Proteínas Protozoarias/metabolismo , Proteínas 14-3-3/genética , Secuencia de Aminoácidos , Animales , Entamoeba histolytica/fisiología , Entamebiasis/metabolismo , Eritrocitos/metabolismo , Femenino , Humanos , Inmunización , Ratones , Ratones Endogámicos BALB C , Filogenia , Proteínas Protozoarias/genética , Homología de Secuencia
5.
J Infect Dis ; 215(10): 1558-1568, 2017 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-28379500

RESUMEN

Background: Crucial gaps in our understanding of Plasmodium vivax reticulocyte invasion and protective immunity have hampered development of vivax vaccines. P. vivax exclusively invades reticulocytes that is mediated by the P. vivax reticulocyte-binding proteins (PvRBPs) specifically PvRBP2c and PvRBP1a. Vivax infections in Duffy-null individuals have suggested the evolution of alternate invasion pathways that may be mediated by the PvRBPs. Thus, PvRBPs appear as potential targets for efficacious P. vivax neutralization. However, there are limited data validating their vaccine efficacy. In the absence of vivax invasion assays, binding-inhibitory activity of antibodies has been reported to be associated with protection and a measure of vaccine potential. Methods: -based analysis was performed of the PvRBP reticulocyte-binding properties and binding-inhibitory activity of specific anti-PvRBP2c/PvRBP1a human antibodies. Results: PvRBP2c and PvRBP1a displayed a distinct reticulocyte-binding specificity, and their specific reticulocyte-binding domains were mapped within their N-terminal regions. Importantly, naturally acquired antibodies against the reticulocyte-binding domains efficaciously blocked reticulocyte binding of native PvRBPs, suggesting that the human immune system produced functional binding-inhibitory antibodies through exposure to vivax malaria. Conclusions: Reticulocyte-binding domains of PvRBP2c/PvRBP1a are targets of naturally acquired binding-inhibitory antibodies, substantiating their promise as candidate antigens against which vaccine-inducible immunity could potentially be boosted through natural infections.


Asunto(s)
Anticuerpos Antiprotozoarios/inmunología , Malaria Vivax/inmunología , Proteínas de la Membrana/inmunología , Plasmodium vivax/inmunología , Unión Proteica/inmunología , Proteínas Protozoarias/inmunología , Animales , Anticuerpos Antiprotozoarios/sangre , Anticuerpos Antiprotozoarios/metabolismo , Antígenos de Protozoos/inmunología , Humanos , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Mapeo Peptídico , Dominios Proteicos , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Ratas , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo
6.
Dev Biol ; 375(1): 33-44, 2013 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-23305818

RESUMEN

Drosophila Tribbles (Trbl) encodes the founding member of the Trib family of kinase-like proteins that regulate cell migration, proliferation, growth and homeostasis. Trbl was identified in a misexpression screen in the ovary as an antagonist of border cell migration and acts in part by directing turnover of the C/EBP protein encoded by the gene slow border cells (slbo). The ability of mammalian Trib isoforms to promote C/EBP turnover during tissue differentiation indicates that this function is highly conserved. To better understand the role of Trbl in cell migration, we tested specific Trbl antisera, a trbl null allele and Trbl transgenes bearing site-directed mutations. Trbl is expressed at high levels in the nuclei of follicle cell epithelia and is downregulated in delaminating epithelia as expression of Slbo (C/EBP) is upregulated. This complementary pattern of expression during subsequent cell migration is achieved by negative feedback whereby slbo represses Trbl expression and trbl is necessary and sufficient to promote Slbo protein turnover. A series of point mutations that scan the conserved kinase domain of Trbl reveal that the conserved DLK catalytic loop is required for Trbl-Slbo binding and turnover, as well as for interactions between Trbl subunits, suggesting a mechanism of Trbl function.


Asunto(s)
Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Proteínas de Ciclo Celular/metabolismo , Movimiento Celular , Proteínas de Drosophila/metabolismo , Drosophila/citología , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Proteínas Potenciadoras de Unión a CCAAT/genética , Dominio Catalítico , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/inmunología , Diferenciación Celular , Movimiento Celular/genética , Proliferación Celular , Drosophila/metabolismo , Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Proteínas de Drosophila/inmunología , Retroalimentación Fisiológica , Femenino , Regulación del Desarrollo de la Expresión Génica , Masculino , Mutación , Oogénesis/genética , Ovario/citología , Ovario/metabolismo , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/inmunología , Interferencia de ARN , ARN Interferente Pequeño , Transgenes
7.
J Neurosurg ; 140(2): 552-559, 2024 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-37548567

RESUMEN

OBJECTIVE: Severe traumatic brain injury (TBI) is a public health issue posing significant morbidity and mortality to afflicted patients. While the effect of time to surgery as the primary factor for survival has been extensively studied, long-term dispositional outcomes following intracranial hemorrhage evacuation have not been well described in the literature. Therefore, the aim of this study was to elicit potential prognostic factors in patients presenting with severe TBI that may have a significant impact on discharge disposition. METHODS: The authors searched the National Trauma Data Bank (NTDB) for patients included between 2010 and 2019, solely focusing on those with a Glasgow Coma Scale score ≤ 8, signifying severe TBI, and with associated intracranial hemorrhage treated via surgical intervention. Numerous characteristics were analyzed, including demographics (age, sex, race, ethnicity, payment status), discharge disposition, time to surgery, pupillary response, midline shift (> 5 mm), and postoperative inpatient complications and comorbidities. Disposition included routine discharge to home, discharge to home with home health services (HHSs), discharge to acute inpatient rehabilitation (AIR), discharge to a skilled nursing facility (SNF)/long-term acute care hospital (LTACH), and death. RESULTS: The authors analyzed data on 7308 patients, 69.6% of whom were White and 11.2% of whom were Black. More young Black and Hispanic patients had severe TBI events than their matched elders, whereas more elderly White patients had severe TBI events than their matched younger counterparts. The most common disposition across all ages was SNF/LTACH. Septuagenarians and octogenarians were 12.1 and 21 times more likely, respectively, to die following a severe TBI than their younger counterparts (p < 0.001). Patients aged 18-29 were 1.7 times more likely to be discharged with HHSs (p < 0.001). Minority race/ethnicity groups were less likely to be discharged to AIR. As age increased, a patient's intensive care unit stay increased by 15 days (p < 0.001) and total hospital length of stay increased by 25 days (p < 0.001). CONCLUSIONS: Neurosurgical evacuation of intracranial hemorrhage in severe TBI has variable long-term morbidity. Utilizing the largest collection of trauma data within the United States, the authors present quantitative evidence on discharge disposition. Understanding these tangible points can help neurosurgeons present potential outcomes to patients, promote preventative care, and generate tangible conversations with patients and their family members.


Asunto(s)
Lesiones Traumáticas del Encéfalo , Lesiones Encefálicas , Anciano , Anciano de 80 o más Años , Humanos , Estados Unidos , Lesiones Traumáticas del Encéfalo/complicaciones , Lesiones Traumáticas del Encéfalo/cirugía , Hemorragia , Alta del Paciente , Complicaciones Posoperatorias , Hemorragias Intracraneales , Estudios Retrospectivos
8.
J Chem Theory Comput ; 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38924093

RESUMEN

New Bayesian parameter estimation methods have the capability to enable more physically realistic and reliable molecular dynamics (MD) simulations by providing accurate estimates of uncertainties of force-field (FF) parameters and associated properties. However, the choice of which Bayesian parameter estimation algorithm to use has not been widely investigated, despite its impact on the effective exploration of parameter space. Here, using a case example of the Embedded Atom Method (EAM) FF parameters, we investigated the ramifications of several of the algorithm choices. We found that Ensemble Slice Sampling (ESS) and Affine-Invariant Ensemble Sampling (AIES) demonstrate a new level of superior performance, culminating in more accurate parameter and property estimations with tighter uncertainty bounds, compared to traditional methods such as Metropolis-Hastings (MH), Gradient Search (GS), and Uniform Random Sampler (URS). We demonstrate that Bayesian Uncertainty Quantification with ESS and AIES leads to significantly more accurate and reliable predictions of the FF parameters and properties. The results suggest that ESS and AIES should be used to obtain more accurate parameter and uncertainty estimations while providing deeper physical insights.

9.
Anal Chem ; 85(12): 6080-8, 2013 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-23679912

RESUMEN

In order to measure the intermolecular binding forces between two halves (or partners) of naturally split protein splicing elements called inteins, a novel thiol-hydrazide linker was designed and used to orient immobilized antibodies specific for each partner. Activation of the surfaces was achieved in one step, allowing direct intermolecular force measurement of the binding of the two partners of the split intein (called protein trans-splicing). Through this binding process, a whole functional intein is formed resulting in subsequent splicing. Atomic force microscopy (AFM) was used to directly measure the split intein partner binding at 1 µm/s between native (wild-type) and mixed pairs of C- and N-terminal partners of naturally occurring split inteins from three cyanobacteria. Native and mixed pairs exhibit similar binding forces within the error of the measurement technique (~52 pN). Bioinformatic sequence analysis and computational structural analysis discovered a zipper-like contact between the two partners with electrostatic and nonpolar attraction between multiple aligned ion pairs and hydrophobic residues. Also, we tested the Jarzynski's equality and demonstrated, as expected, that nonequilibrium dissipative measurements obtained here gave larger energies of interaction as compared with those for equilibrium. Hence, AFM coupled with our immobilization strategy and computational studies provides a useful analytical tool for the direct measurement of intermolecular association of split inteins and could be extended to any interacting protein pair.


Asunto(s)
Anticuerpos Inmovilizados/química , Anticuerpos Inmovilizados/metabolismo , Inteínas/fisiología , Empalme de Proteína/fisiología , Secuencia de Aminoácidos , Anticuerpos Inmovilizados/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Datos de Secuencia Molecular , Unión Proteica/fisiología , Estructura Secundaria de Proteína
10.
Perspect Clin Res ; 14(4): 161-166, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38025292

RESUMEN

Electronic health records (EHRs) constitute vital statistics, current health condition, ongoing therapies, and patient data; hence, their interoperability could be useful for epidemiologic and clinical research. Fast Healthcare Interoperability Resources (FHIR) and blockchain are currently "in-use" and tested for exchange of such data. The annual scientific production of publications for both FHIR and blockchain shows steady growth. The data interoperability and electronic data interchange have been introduced in the field of EHR in 2020, hence inferring that data interoperability is relatively a new domain. The thematic mapping suggested "interoperability" of EHR is well-developed and important for the structure of the research field.

11.
J Phys Chem B ; 127(29): 6500-6506, 2023 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-37440468

RESUMEN

In this paper, the effect of electric fields on phase equilibria through polarization is investigated. A relation is derived for the chemical potential of a system, where the electric field is localized over a liquid phase mixture in equilibrium with a vapor phase mixture. This relation is then applied to a water-ethanol mixture to explore the effect of polarization-based electric fields on the liquid phase composition. It is observed that the quadratic dependence on electric field strength produces little effect below field strengths of approx. 10 MV/m. However, above this field strength, the mole fraction of water in the liquid phase grows rapidly, increasing by a factor of 8 for a water vapor phase fraction of 0.2 and a field strength of 500 MV/m, which approaches the dielectric breakdown strength of water. Nonetheless, this field strength could be achievable with microfluidic experimental setups.

12.
RSC Adv ; 13(32): 22185-22192, 2023 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-37492504

RESUMEN

A novel non-electrophoretic, electric field-based separation mechanism capable of transporting ions based on their dielectric properties is presented here for the first time. Though this polarization-based mechanism behaves similarly to dielectrophoresis, the separation mechanism is remarkably very efficient at small length scales compared to any dielectrophoretic separation mechanism for particles. For an applied electric field of strength as low as ∼0.75 MV m-1 across a 100 µm channel, the working solute - sodium fluorescein - is shown to decrease in its concentration by ≈20% in electric field region relative to the non electric field region. The existing macroscopic theoretical models like electrohydrodynamics and equilibrium thermodynamics are shown to underestimate the concentration change by two orders of magnitude for the same electric field strength. This surprisingly large difference between theory and experimental results suggests that the electric field-based equilibrium thermodynamic model lacks a key physics.

13.
Appl Spectrosc ; 77(6): 616-622, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37211622

RESUMEN

A novel method of measuring the influence of high electric fields on the Raman scattering of fluids is introduced, which can help understand various interactions of a fluid with the high electric field. The microfluidic chip can impose highly controlled, uniform electric fields across the measurement volume with blocked electrodes, eliminating spurious reactions at the electrode surface. The developed methodology and the experimental setup are utilized to examine the effect of the electric field on three of the stretching vibrations of ethanol in water-ethanol mixtures with varying concentrations of ethanol and effective electric fields up to 1.0MV/m. The increase in the electric field is seen to broadly decrease the intensity of Raman scattering due to a decrease in the polarizability of the ethanol molecules. Although this effect is uniform for all water-ethanol mixtures, it reduces in mixtures with high weight-fractions of water because of the already reduced polarizability of an ethanol molecule due to hydrogen bonding. The combined effect of hydrogen bonding and increase in temperature due to the alternating high electric field even results in an increase in the magnitude of peak intensity for relatively low-weight fractions of ethanol.


Asunto(s)
Etanol , Espectrometría Raman , Espectrometría Raman/métodos , Etanol/química , Agua/química , Enlace de Hidrógeno
14.
J Phys Chem B ; 127(42): 9181-9190, 2023 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-37844296

RESUMEN

This study investigates phase equilibrium manipulation in nonideal mixtures through a combined capillary and external electric field approach. Utilizing thermodynamic principles, an expression is established for estimating the equilibrium liquid mole fraction in a confined system subjected to a localized electric field within a capillary that is filled with a liquid phase in equilibrium with its vapor counterpart. Applied to a water-ethanol system, the model suggests large shifts in the equilibrium liquid mole fraction of water due to the electric field and capillary effects. These findings reveal that while the capillary's influence remains negligible for radii exceeding 10 nm, capillaries of smaller dimensions, when exposed to electric fields of around 300 MV/m, can amplify the equilibrium liquid water mole fraction by up to 55%. This suggests the potential for phase equilibrium control through larger capillaries and lower electric fields, while intriguing complexities arise at very small radii.

15.
World J Exp Med ; 13(3): 17-27, 2023 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-37396884

RESUMEN

BACKGROUND: Cancer diagnosis is increasing around the world and in the Democratic Republic of the Congo (DRC). The proportion of thyroid cancer has increased over the past three decades. There are very few studies on cancer epidemiology, and in particular on thyroid cancer in the DRC. AIM: To establish the most recent proportion of thyroid cancer in the DRC compared to other cancers. METHODS: This is a retrospective and descriptive study of 6106 consecutive cancer cases listed in the pathological registers of 4 Laboratories in the city of Kinshasa. This study included all cancer cases recorded in the registers between 2005 and 2019. RESULTS: From a sample of 6106 patients, including all cancer types, 68.3% cases were female and 31.7% were male. Breast and cervical cancer were the most common types of cancer in women and, prostate and skin cancer were the most common types in men. Thyroid cancer was sixth in proportion in women and eleventh in men compared to all cancers. Papillary carcinoma was the most common of thyroid cancers. Rare cancers such as anaplastic and medullary thyroid carcinomas had a proportion of 7% and 2%, respectively. CONCLUSION: Newer diagnostic tools led to a surge in cancer diagnoses in the DRC. Thyroid cancer has more than doubled its proportion over the last several decades in the country.

16.
Perspect Clin Res ; 13(1): 3-11, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35198422

RESUMEN

Indian healthcare sector is a fast-growing industry which is expected to reach $280 billion by 2025. Medical devices market in India is one of the top 20 medical device markets in the world. It is currently valued at $5.2 billion and is expected to reach $50 billion by 2025. However, India does not manufacture many devices indigenously and still imports approximately 70% of its medical devices. Manufacturing and monitoring of medical devices are highly regulated activities. In India, there were no specific medical device regulations and devices were regulated under the Drugs and Cosmetics Act, 1940. To fulfill this gap, Central Drug Standard Control Organization released Indian Medical Device Rules, 2017, which are the new regulations for medical devices in India. Keeping pace with the requirements, these were amended as Medical Devices (Amendment) Rules, 2020, which has come into force in April 2020. These rules cover various aspects of device related regulations, including classification, registration, manufacturing and import, labeling, sales, and postmarket requirements, etc. The rules are a positive step and encompass most of the European Union (EU) approval process, which mandates that the devices are safe and performs its intended function. However, with rapid advancements in medical device technology, much is desired in clarity and revamping of the current regulatory system to harmonize standards to be in-line with advanced regulations like EU.

17.
Langmuir ; 27(5): 1830-6, 2011 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-21182242

RESUMEN

Removing adsorbed protein from metals has significant health and industrial consequences. There are numerous protein-adsorption studies using model self-assembled monolayers or polymeric substrates but hardly any high-resolution measurements of adsorption and removal of proteins on industrially relevant transition metals. Surgeons and ship owners desire clean metal surfaces to reduce transmission of disease via surgical instruments and minimize surface fouling (to reduce friction and corrosion), respectively. A major finding of this work is that, besides hydrophobic interaction adhesion energy, water content in an adsorbed protein layer and secondary structure of proteins determined the access and hence ability to remove adsorbed proteins from metal surfaces with a strong alkaline-surfactant solution (NaOH and 5 mg/mL SDS in PBS at pH 11). This is demonstrated with three blood proteins (bovine serum albumin, immunoglobulin, and fibrinogen) and four transition metal substrates and stainless steel (platinum (Pt), gold (Au), tungsten (W), titanium (Ti), and 316 grade stainless steel (SS)). All the metallic substrates were checked for chemical contaminations like carbon and sulfur and were characterized using X-ray photoelectron spectroscopy (XPS). While Pt and Au surfaces were oxide-free (fairly inert elements), W, Ti, and SS substrates were associated with native oxide. Difference measurements between a quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance spectroscopy (SPR) provided a measure of the water content in the protein-adsorbed layers. Hydrophobic adhesion forces, obtained with atomic force microscopy, between the proteins and the metals correlated with the amount of the adsorbed protein-water complex. Thus, the amount of protein adsorbed decreased with Pt, Au, W, Ti and SS, in this order. Neither sessile contact angle nor surface roughness of the metal substrates was useful as predictors here. All three globular proteins behaved similarly on addition of the alkaline-surfactant cleaning solution, in that platinum and gold exhibited an increase, while tungsten, titanium, and stainless steel showed a decrease in weight. According to dissipation measurements with the QCM-D, the adsorbed layer for platinum and gold was rigid, while that for the tungsten, titanium, and stainless steel was much more flexible. The removal efficiency of adsorbed-protein by alkaline solution of SDS depended on the water content of the adsorbed layers for W, Ti, and SS, while for Pt and Au, it depended on secondary structural content. When protein adsorption was high (Pt, Au), protein-protein interactions and protein-surface interactions were dominant and the removal of protein layers was limited. Water content of the adsorbed protein layer was the determining factor for how efficiently the layer was removed by alkaline SDS when protein adsorption was low. Hence, protein-protein and protein-surface interactions were minimal and protein structure was less perturbed in comparison with those for high protein adsorption. Secondary structural content determined the efficient removal of adsorbed protein for high adsorbed amount.


Asunto(s)
Proteínas Sanguíneas/química , Metales/química , Agua/química , Adsorción , Animales , Proteínas Sanguíneas/aislamiento & purificación , Bovinos , Estructura Secundaria de Proteína , Propiedades de Superficie
18.
Indian J Med Ethics ; -(-): 1-2, 2021 09 18.
Artículo en Inglés | MEDLINE | ID: mdl-34730102

RESUMEN

Human volunteers are key stakeholders in any clinical research. For inclusiveness it is ethically imperative to ensure data transparency even after the completion of clinical trials. This is also supported by the Declaration of Helsinki, which in a statement of ethical principles, provides guidance to physicians and other participants in medical research involving human volunteers, suggesting that they have the full right to the results of a trial (1).

19.
Vaccines (Basel) ; 9(7)2021 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-34358198

RESUMEN

A fusion chimeric vaccine comprising multiple protective domains of different blood-stage Plasmodium falciparum antigens is perhaps necessary for widening the protective immune responses and reducing the morbidity caused by the disease. Here we continue to build upon the prior work of developing a recombinant fusion chimera protein, His-tagged PfMSP-Fu24, by producing it as a tag-free recombinant protein. In this study, tag-free recombinant PfMSPFu24 (rFu24) was expressed in Escherichia coli, and the soluble protein was purified using a three-step purification involving ammonium sulphate precipitation followed by 2-step ion exchange chromatography procedures and shown that it was highly immunogenic with the human-compatible adjuvant Alhydrogel. We further investigated two dipeptides, phenylalanine-α, ß-dehydrophenylalanine (FΔF) and Leucine-α, ß-dehydrophenylalanine (LΔF) based hydrogels as effective delivery platforms for rFu24. These dipeptides self-assembled spontaneously to form a highly stable hydrogel under physiological conditions. rFu24 was efficiently entrapped in both the F∆F and L∆F hydrogels, and the three-dimensional (3D) mesh-like structures of the hydrogels remained intact after the entrapment of the antigen. The two hydrogels significantly stimulated rFu24-specific antibody titers, and the sera from the immunized mice showed an invasion inhibitory activity comparable to that of Alhydrogel. Easily synthesized dipeptide hydrogels can be used as an effective antigen delivery platform to induce immune responses.

20.
Langmuir ; 26(12): 9695-702, 2010 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-20334401

RESUMEN

We offer a novel process to render hydrophobic surfaces resistant to relatively small proteins during adsorption. This was accomplished by self-assembly of a well-known natural osmolyte, trimethylamine oxide (TMAO), a small amphiphilic molecule, on a hydrophobic alkanethiol surface. Measurements of lysozyme (LYS) adsorption on several homogeneous substrates formed from functionalized alkanethiol self-assembled monolayers (SAMs) in the presence and absence of TMAO, and direct interaction energy between the protein and functionalized surfaces, demonstrate the protein-resistant properties of a noncovalently adsorbed self-assembled TMAO layer. Molecular dynamics simulations clearly show that TMAO molecules concentrate near the CH(3)-SAM surface and are preferentially excluded from LYS. Interestingly, TMAO molecules adsorb strongly on a hydrophobic CH(3)-SAM surface, but a trade-off between hydrogen bonding with water, and hydrophobic interactions with the underlying substrate results in a nonintuitive orientation of TMAO molecules at the interface. Additionally, hydrophobic interactions, usually responsible for nonspecific adsorption of proteins, are weakly affected by TMAO. In addition to TMAO, other osmolytes (sucrose, taurine, and betaine) and a larger homologue of TMAO (N,N-dimethylheptylamine-N-oxide) were tested for protein resistance and only N,N-dimethylheptylamine-N-oxide exhibited resistance similar to TMAO. The principle of osmolyte exclusion from the protein backbone is responsible for the protein-resistant property of the surface. We speculate that this novel process of surface modification may have wide applications due to its simplicity, low cost, regenerability, and flexibility.


Asunto(s)
Interacciones Hidrofóbicas e Hidrofílicas , Metilaminas/química , Proteínas/química , Adsorción , Simulación de Dinámica Molecular , Muramidasa/química , Propiedades de Superficie
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