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1.
J Biotechnol ; 391: 72-80, 2024 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-38876311

RESUMEN

The lipase from Prunus dulcis almonds was inactivated under different conditions. At pH 5 and 9, enzyme stability remained similar under the different studied buffers. However, when the inactivation was performed at pH 7, there were some clear differences on enzyme stability depending on the buffer used. The enzyme was more stable in Gly than when Tris was employed for inactivation. Then, the enzyme was immobilized on methacrylate beads coated with octadecyl groups at pH 7 in the presence of Gly, Tris, phosphate and HEPES. Its activity was assayed versus triacetin and S-methyl mandelate. The biocatalyst prepared in phosphate was more active versus S-methyl mandelate, while the other ones were more active versus triacetin. The immobilized enzyme stability at pH 7 depends on the buffer used for enzyme immobilization. The buffer used in the inactivation and the substrate used determined the activity. For example, glycine was the buffer that promoted the lowest or the highest stabilities depending on the substrate used to quantify the activities.


Asunto(s)
Estabilidad de Enzimas , Enzimas Inmovilizadas , Lipasa , Prunus dulcis , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/metabolismo , Lipasa/química , Lipasa/metabolismo , Prunus dulcis/química , Prunus dulcis/enzimología , Tampones (Química) , Concentración de Iones de Hidrógeno , Triacetina/química , Triacetina/metabolismo , Glicina/química , Glicina/metabolismo , Trometamina/química , Biocatálisis , Especificidad por Sustrato , Fosfatos/química , Fosfatos/metabolismo , HEPES/química
2.
J Assist Reprod Genet ; 41(5): 1341-1356, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38436798

RESUMEN

PURPOSE/STUDY QUESTION: Does piercing oocyte membranes during ICSI allow the influx of surrounding zwitterionic buffer into human oocytes and result in altered developmental competence? METHODS: Human oocytes directed to IRB-approved research were used to determine the unrestricted influx of surrounding buffer into the oocyte after piercing of membranes via confocal fluorescence microscopy (n = 80 human MII oocytes) and the influence of the select buffer influx of HEPES, MOPS, and bicarbonate buffer on the oocyte transcriptome using ultra-low input RNA sequencing (n = 40 human MII oocytes). RESULTS: Piercing membranes of human MII oocytes during sham-ICSI resulted in the unrestricted influx of surrounding culture buffer into the oocyte that was beyond technician control. Transcriptome analysis revealed statistically significant decreased cytoskeletal transcripts in the pierced buffer cohorts, higher levels of embryo competency transcripts (IGF2 and G6PD) in the bicarbonate buffer cohort, higher levels of stress-induced transcriptional repressor transcripts (MAF1) in the HEPES and MOPS cohorts, and decreased levels of numerous chromosomal maintenance transcripts (SMC3) in the HEPES buffer cohort. The HEPES buffer cohort also revealed higher levels of transcripts suggesting increased oxidative (GPX1) and lysosomal stress (LAMP1). CONCLUSION: The influence of zwitterionic buffer on intrinsic cellular mechanisms provides numerous concerns for their use in IVF clinical applications. The primary concern is the ICSI procedure, in which the surrounding buffer is allowed influx into the oocytes after membrane piercing. Selecting a physiological bicarbonate buffer may reduce imposed stress on oocytes, resulting in improved embryo development and clinical results because intracellular MOPS, and especially HEPES, may negatively impact intrinsic biological mechanisms, as revealed by transcriptome changes. These findings further support the utilization of bicarbonate buffer as the oocyte-holding medium during ICSI.


Asunto(s)
Oocitos , Inyecciones de Esperma Intracitoplasmáticas , Transcriptoma , Humanos , Inyecciones de Esperma Intracitoplasmáticas/métodos , Oocitos/metabolismo , Oocitos/crecimiento & desarrollo , Femenino , Transcriptoma/genética , Tampones (Química) , Adulto , HEPES , Masculino , Desarrollo Embrionario/genética , Fertilización In Vitro/métodos
3.
Biophys J ; 123(6): 718-729, 2024 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-38368506

RESUMEN

Preparation of cryoelectron microscopy (cryo-EM) grids for imaging of amyloid fibrils is notoriously challenging. The human islet amyloid polypeptide (hIAPP) serves as a notable example, as the majority of reported structures have relied on the use of nonphysiological pH buffers, N-terminal tags, and seeding. This highlights the need for more efficient, reproducible methodologies that can elucidate amyloid fibril structures formed under diverse conditions. In this work, we demonstrate that the distribution of fibrils on cryo-EM grids is predominantly determined by the solution composition, which is critical for the stability of thin vitreous ice films. We discover that, among physiological pH buffers, HEPES uniquely enhances the distribution of fibrils on cryo-EM grids and improves the stability of ice layers. This improvement is attributed to direct interactions between HEPES molecules and hIAPP, effectively minimizing the tendency of hIAPP to form dense clusters in solutions and preventing ice nucleation. Furthermore, we provide additional support for the idea that denatured protein monolayers forming at the interface are also capable of eliciting a surfactant-like effect, leading to improved particle coverage. This phenomenon is illustrated by the addition of nonamyloidogenic rat IAPP (rIAPP) to a solution of preaggregated hIAPP just before the freezing process. The resultant grids, supplemented with this "spectator protein", exhibit notably enhanced coverage and improved ice quality. Unlike conventional surfactants, rIAPP is additionally capable of disentangling the dense clusters formed by hIAPP. By applying the proposed strategies, we have resolved the structure of the dominant hIAPP polymorph, formed in vitro at pH 7.4, to a final resolution of 4 Å. The advances in grid preparation presented in this work hold significant promise for enabling structural determination of amyloid proteins which are particularly resistant to conventional grid preparation techniques.


Asunto(s)
Amiloide , Hielo , Ratas , Animales , Humanos , Amiloide/química , Microscopía por Crioelectrón , HEPES , Polipéptido Amiloide de los Islotes Pancreáticos/química
4.
Spectrochim Acta A Mol Biomol Spectrosc ; 308: 123670, 2024 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-38006866

RESUMEN

A highly sensitive detection platform for heparin was constructed via the utilization of a commercially available cationic fluorescent dye (cresyl violet acetate, CV) as a fluorescence probe. The electrostatic binding between CV and heparin quenched the fluorescence in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic (HEPES) buffer solution (10 mM, pH 7.1). CV was highly selective towards heparin over other potential inferring substances. The detection limit of heparin detection was 5.19 ng/mL, and the linear working range was 0 ∼ 1 µg/mL in HEPES solution. In 1 % serum, the detection platform based on the fluorescence "turn-off" behavior of CV was also successfully constructed with a detection limit of 5.86 ng/mL in the linear range of 0 ∼ 0.8 µg/mL. Moreover, the CV-heparin complex was considered a potential sensor platform for the detection of protamine because of its stronger affinity for heparin and protamine.


Asunto(s)
Colorantes Fluorescentes , Heparina , Colorantes Fluorescentes/química , HEPES , Espectrometría de Fluorescencia , Límite de Detección , Protaminas
5.
J Struct Biol ; 215(4): 108034, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37805153

RESUMEN

Transcription is carried out by the RNA polymerase and is regulated through a series of interactions with transcription factors. Catabolite activator repressor (Cra), a LacI family transcription factor regulates the virulence gene expression in Enterohaemorrhagic Escherichia coli (EHEC) and thus is a promising drug target for the discovery of antivirulence molecules. Here, we report the crystal structure of the effector molecule binding domain of Cra from E. coli (EcCra) in complex with HEPES molecule. Based on the EcCra-HEPES complex structure, ligand screening was performed that identified sulisobenzone as an potential inhibitor of EcCra. The electrophoretic mobility shift assay (EMSA) and in vitro transcription assay validated the sulisobenzone binding to EcCra. Moreover, the isothermal titration calorimetry (ITC) experiments demonstrated a 40-fold higher binding affinity of sulisobenzone (KD 360 nM) compared to the HEPES molecule. Finally, the sulisobenzone bound EcCra complex crystal structure was determined to elucidate the binding mechanism of sulisobenzone to the effector binding pocket of EcCra. Together, this study suggests that sulisobenzone may be a promising candidate that can be studied and developed as an effective antivirulence agent against EHEC.


Asunto(s)
Escherichia coli , Factores de Transcripción , Factores de Transcripción/metabolismo , Escherichia coli/metabolismo , Proteínas Represoras/genética , HEPES/metabolismo , Regulación Bacteriana de la Expresión Génica , Unión Proteica
6.
Discov Med ; 35(177): 553-564, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37553309

RESUMEN

PURPOSE: To evaluate the effects of various retinal neurotransmitters on temporal resolution, particularly, on the Critical Flicker Fusion Frequency (CFF), which has been previously applied in ophthalmic pathophysiologic research. METHODS: A binocular physiologic electroretinogram was performed on adult mice. Animals in the control group were injected in the right eye with 1 µL of phosphate-buffered saline (PBS). Animals in the experimental group were injected in the left eye with 1 µL of PBS and in the right eye with 1 µL of PBS to which different molecules were added: 2-amino-4-phosphonobutyric acid (APB), Glutamate, γ-aminobutyric acid (GABA), 6,7-dinitroquinoxaline-2,3-dione (DNQX), Bicuculline, Glycine, and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). Initially, rod response was recorded and later the cone response. RESULTS: APB suppressed the rod-driven, but not the cone-driven flicker response. The other agents severely affected the lower flickering frequency response amplitude, in particular, at 3 Hz. The threshold of CFF was lowered from 50 Hz to 40 Hz after applying APB, Glycine, and HEPES. GABA remarkably enhanced rod-driven and cone-driven flicker response at 3 Hz, whereas Glutamate and GABA/Glutamate only did in rod-driven flicker response. CONCLUSIONS: Both ON and OFF visual pathways were implied in cone-driven response, but only the ON visual pathway appears to play a relevant role in rod-driven flicker response. Flicker response seems to be enhanced by horizontal cells both in rod-driven and cone-driven response. In addition, due to the greater sensitivity of the flicker at low frequencies, it is suggested that pathophysiological studies should be carried out at said frequencies.


Asunto(s)
Electrorretinografía , Vías Visuales , Ratones , Animales , HEPES , Estimulación Luminosa , Ácido gamma-Aminobutírico , Glutamatos
7.
Biomaterials ; 301: 122243, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37480759

RESUMEN

Lipid nanoparticles (LNPs) have shown great promise as delivery vehicles to transport messenger ribonucleic acid (mRNA) into cells and act as vaccines for infectious diseases including COVID-19 and influenza. The ionizable lipid incorporated within the LNP is known to be one of the main driving factors for potency and tolerability. Herein, we describe a novel family of ionizable lipids synthesized with a piperazine core derived from the HEPES Good buffer. These ionizable lipids have unique asymmetric tails and two dissimilar degradable moieties incorporated within the structure. Lipids tails of varying lengths, degrees of unsaturation, branching, and the inclusion of additional ester moieties were evaluated for protein expression. We observed several key lipid structure activity relationships that correlated with improved protein production in vivo, including lipid tails of 12 carbons on the ester side and the effect of carbon spacing on the disulfide arm of the lipids. Differences in LNP physical characteristics were observed for lipids containing an extra ester moiety. The LNP structure and lipid bilayer packing, visualized through Cryo-TEM, affected the amount of protein produced in vivo. In non-human primates, the Good HEPES LNPs formulated with an mRNA encoding an influenza hemagglutinin (HA) antigen successfully generated functional HA inhibition (HAI) antibody titers comparable to the industry standards MC3 and SM-102 LNPs, demonstrating their promise as a potential vaccine.


Asunto(s)
COVID-19 , Vacunas contra la Influenza , Gripe Humana , Animales , Humanos , HEPES , Membrana Dobles de Lípidos , Carbono , Ésteres , Vacunas de ARNm
8.
Curr Protoc ; 3(7): e833, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37462371

RESUMEN

Western blotting is a method widely used in cell and molecular biology for the specific detection of proteins in biological samples. It is time-consuming and normally takes up to 2 days to complete. This protocol introduces a more time-efficient method to complete western blots, covering the preparation of protein extracts (including strategies for solubilization), electrophoretic separation of proteins, transfer of proteins to the membrane, and probing with antibodies. We describe an SDS-PAGE protocol that achieves a gradient-like separation of proteins (10-400 kDa) on a single-percentage polyacrylamide gel in only 45 min. Additionally, we present a rapid (10-14 min) semi-dry transfer of proteins from standard Tris/glycine polyacrylamide gels onto a membrane using homemade Tris/HEPES- or Tris/EPPS-based buffers. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) Support Protocol 1: Cell lysis and protein extraction Support Protocol 2: Protein quantification with BCA assay and sample preparation for loading on gel Basic Protocol 2: Protein transfer with a fast semi-dry transfer (FSDT) buffer Basic Protocol 3: Immunoprobing, chemiluminescent visualization, stripping, and reuse of membranes.


Asunto(s)
Proteínas , Proteínas/análisis , HEPES , Tiempo , Electroforesis en Gel de Poliacrilamida , Western Blotting
9.
Biomater Sci ; 11(14): 4930-4937, 2023 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-37306673

RESUMEN

Photodynamic therapy (PDT) is becoming an efficient antibacterial strategy without drug-resistance. Here, we report a promising reactive oxygen species (ROS) conversion strategy to increase the antibacterial efficiency of an Eosin Y (EOS)-based PDT system. Based on visible-light illumination, EOS generates a high concentration of singlet oxygen (1O2) in the solution. With the introduction of HEPES in the EOS system, it can almost completely convert 1O2 to hydrogen peroxide (H2O2). The orders-of-magnitude increases in the half-lives of the ROS (H2O2vs.1O2) present in the solution can enable more persistent oxidation ability. Thus, it is able to increase the bactericidal efficiency (against S. aureus) from 37.9% to 99.9%, promote the inactivation efficiency of methicillin-resistant S. aureus (MRSA) from 26.9% to 99.4%, and enhance the eradication rate of MRSA biofilm from 69% to 90%. Further in vivo investigation showed that the increased oxidation ability of the EOS/HEPES PDT system can enable quicker healing and maturing (even better than that for vancomycin administration) of MRSA-infected skin wounds on rats. This strategy may find many creative applications for the efficient eradication of bacteria and other pathogenic microorganisms.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Fotoquimioterapia , Ratas , Animales , Staphylococcus aureus/fisiología , Especies Reactivas de Oxígeno , Eosina Amarillenta-(YS) , Peróxido de Hidrógeno , HEPES , Antibacterianos/farmacología , Oxígeno , Fármacos Fotosensibilizantes/farmacología
10.
Langmuir ; 39(22): 7632-7641, 2023 06 06.
Artículo en Inglés | MEDLINE | ID: mdl-37204470

RESUMEN

Iron oxide nanoparticles (IONPs) have been studied extensively for biomedical applications, which require that they be aqueous-stable at physiological pH. The structures of some of these buffers, however, may also allow for binding to surface iron, thus potentially exchanging with functionally relevant ligands, and altering the desired properties of the nanoparticles. We report here on the interactions of five common biologically relevant buffers (MES, MOPS, phosphate, HEPES, and Tris) with iron oxide nanoparticles through spectroscopic studies. The IONPs in this study are capped with 3,4-dihydroxybenzoic acid (3,4-DHBA) to serve as models for IONP functionalized with catechol ligands. Unlike previous studies, which relied exclusively on dynamic light scattering (DLS) and ζ-potential measurements to characterize buffer interactions with IONPs, we use Fourier transform infrared (FTIR) and ultraviolet-visible (UV-visible) spectroscopic techniques to characterize the IONP surface to demonstrate binding of buffers and etching of the IONP surface. Our findings establish that phosphate and Tris bind to the IONP surface, even in the presence of strongly bound catechol ligands. We further observe significant etching of IONPs in Tris buffer, with the release of surface Fe into solution. Minor etching is noted in HEPES, and to a lesser degree, in MOPS, while no etching is observed in MES. Our findings suggest that, while morpholino buffers, such as MES and MOPS, may be more appropriate for use with IONPs, proper buffer selection should always be considered on a case-by-case basis.


Asunto(s)
Hierro , Nanopartículas , HEPES/química , Ligandos , Nanopartículas Magnéticas de Óxido de Hierro , Tampones (Química) , Nanopartículas/química
11.
FEMS Microbiol Ecol ; 99(7)2023 06 16.
Artículo en Inglés | MEDLINE | ID: mdl-37245057

RESUMEN

Building on a previously developed workflow for rapid and sensitive pathogen detection by qPCR, this work has established a sample treatment strategy that produces consistent quantification efficiencies (QEs) for Campylobacter jejuni against a complex and highly variable sample matrix from a suburban river. The individual treatments most effective at minimizing the inhibitory effects of the sample matrix were pH buffering with HEPES (50 mM, pH 5.7) and addition of the surfactant Tween 20 (2% v/v). Unexpectedly, sample acidification (pH 4-5) resulting from the use of aged Tween 20 that had undergone partial hydrolysis, appeared to play a key role in enhancing QE. This effect could be replicated by direct pH adjustment with dilute hydrochloric acid and may be linked to the solubilization and removal of inhibitory particles at an acidic pH. While the effectiveness of each individual treatment method varied, a combined treatment of either HEPES buffer + Tween 20, or direct pH adjustment + Tween 20, consistently produced QEs of 60%-70% and up to 100%, respectively, over a sampling period of one year. The consistency and scalability of this workflow make it a suitable alternative to culture-based ISO methods for detecting Campylobacter spp.


Asunto(s)
Campylobacter coli , Campylobacter jejuni , Campylobacter jejuni/genética , Polisorbatos , HEPES , Agua
12.
Fish Physiol Biochem ; 49(4): 559-576, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37193910

RESUMEN

Reliable short-term chilled sperm storage is a critical prerequisite to using advanced reproductive techniques for captive breeding of barramundi (Asian sea bass; Lates calcarifer). Marine Ringer's solution (MRS) is a common non-activating medium (NAM) and has previously been used to store sperm from wild-caught barramundi. However, MRS-stored spermatozoa from captive-bred barramundi were observed to lyse within 30 min incubation. Therefore, this study aimed to optimize the composition of NAM for short-term chilled storage by characterizing and mimicking the biochemical profile of seminal and blood plasma of captive-bred barramundi. To further understand the effect of each component, osmolality was first examined to determine its effect on sperm viability. Thereafter, the effects of NaHCO3, pH, and Na+ and K+ concentrations on sperm motility were investigated. Optimization of the NAM formula was achieved through iterative adaptions. The increase in NAM osmolality from 260 to 400 mOsm/kg led to a significant improvement in sperm viability. Moreover, using HEPES instead of NaHCO3 as buffering agent significantly enhanced sperm motility and velocity. As a result, sperm samples diluted with optimized NAM (185 mM NaCl, 5.1 mM KCl, 1.6 mM CaCl2·2H2O, 1.1 mM MgSO4·7H2O, 10.0 mM HEPES, 5.6 mM D+ glucose, 400 mOsm/kg, pH 7.4) and stored at 4 °C showed no significant loss in total motility for up to 48 h and retained progressive motility for up to 72 h. The optimized NAM developed in this study significantly extended the functional lifespan of spermatozoa during chilled storage, permitting the ongoing development of advanced reproductive technologies for barramundi.


Asunto(s)
Perciformes , Preservación de Semen , Masculino , Animales , Semen , Motilidad Espermática , HEPES/farmacología , Preservación de Semen/veterinaria , Preservación de Semen/métodos , Espermatozoides
13.
Food Res Int ; 165: 112484, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36869497

RESUMEN

The current systematic study sought to examine the potential use of three Good's buffers (MES, MOPS and HEPES) in inhibiting myofibrillar protein (MFP) denaturation induced by acidity changes. The highest degree of acidity variation was found in the center and bottom of large bottles due to the freeze-concentration effect. Good's buffer tended to basify during freezing, and it could prevent the crystallization of sodium phosphate (Na-P) buffer. Acidification upon freezing Na-P disrupted the natural conformation of MFP and induced the formation of large proteins aggregates with tight packing. The 15 mM MES, 20 mM MOPS, and 30 mM HEPES were respectively added to neutralize the strong acidity drop induced by freezing 20 mM Na-P, and all of them significantly improved the stability of the MFP conformation (P < 0.05). This work is not only critical to meet the growing demand for protein, but also groundbreaking for broadening the applicability of Good's buffers in the food industry.


Asunto(s)
Congelación , HEPES , Conformación Proteica , Cristalización , Desnaturalización Proteica
14.
J Equine Vet Sci ; 123: 104245, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36773851

RESUMEN

This study aimed to select high-quality spermatozoa by sperm separation by magnetic activation of the fresh equine semen, compared to density gradient centrifugation and evaluating cell quality after selection. The semen of 10 stallions was collected by the artificial vagina technique. The samples analyzed were: (1) fresh semen; (2) density gradient centrifugation (DGC); (3) separation by magnetic activation (MASS) (nonapoptotic portion NAP); (4) separation by MASS (apoptotic portion-APT). Was analyzed: motility (light microscopy), concentration (Neubauer chamber), semen morphology (humid chamber in phase contrast), and supravital test (eosin/nigrosine). In DGC, 20 × 106 spermatozoa were used in the gradient of Percoll at 90% and 45% (400 µL each), centrifugation at 900 G/5 min, the pellet was diluted in HEPES. In MASS, 10 × 106 spermatozoa were diluted in 1.5 mL of HEPES, centrifugation at 300 G/10 min, pellet was resuspended in 150 µL of HEPES with 20 µL of nanoparticles bound to annexin V, incubation for 15 minutes and filtered in the magnetic separation column. The nonapoptotic fraction was collected directly and the apoptotic fraction after removal the column from the magnet and adding 300 µL of HEPES. The total abnormalities were 43.2% ± 2.78%, with the DGC and MASS being effective in reducing sperm abnormality by 15.6% ± 2.10% and 24.30% ± 1.63%, respectively, like the observed for the number of cells with intact membranes (50% lower in the APT portion). This nanotechnological method is efficient in producing high-quality semen samples for assisted reproduction procedures.


Asunto(s)
Semen , Motilidad Espermática , Femenino , Masculino , Animales , Caballos , HEPES/metabolismo , Motilidad Espermática/fisiología , Centrifugación por Gradiente de Densidad/veterinaria , Espermatozoides/metabolismo , Reproducción , Fenómenos Magnéticos
15.
Int J Mol Sci ; 24(4)2023 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-36834538

RESUMEN

To determine the origin of oscillatory potentials (OPs), binocular electroretinogram (ERG) recordings were performed under light and dark adaptation on adult healthy C57BL/6J mice. In the experimental group, 1 µL of PBS was injected into the left eye, while the right eye was injected with 1 µL of PBS containing different agents: APB, GABA, Bicuculline, TPMPA, Glutamate, DNQX, Glycine, Strychnine, or HEPES. The OP response depends on the type of photoreceptors involved, showing their maximum response amplitude in the ERG induced by mixed rod/cone stimulation. The oscillatory components of the OPs were affected by the injected agents, with some drugs inducing the complete abolition of oscillations (APB, GABA, Glutamate, or DNQX), whereas other drugs merely reduced the oscillatory amplitudes (Bicuculline, Glycine, Strychnine, or HEPES) or did not even affect the oscillations (TPMPA). Assuming that rod bipolar cells (RBC) express metabotropic Glutamate receptors, GABAA, GABAC, and Glycine receptors and that they release glutamate mainly on Glycinergic AII amacrine cells and GABAergic A17 amacrine cells, which are differently affected by the mentioned drugs, we propose that RBC-AII/A17 reciprocal synapses are responsible for the OP generation in the ERG recordings in the mice. We conclude that the reciprocal synapses between RBC and AII/A17 are the basis of the ERG OP oscillations of the light response, and this fact must be taken into consideration in any ERG test that shows a decrease in the OPs' amplitude.


Asunto(s)
Enfermedades de la Retina , Estricnina , Ratones , Animales , Estricnina/farmacología , Bicuculina , HEPES , Ratones Endogámicos C57BL , Retina , Glicina , Ácido gamma-Aminobutírico , Glutamatos
16.
Biophys Chem ; 294: 106963, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36716683

RESUMEN

ßL-crystallin aggregation due to oxidative damage in the presence of H2O2 and ferric chloride was studied in-vitro under conditions close to physiological. It was shown that the protein aggregation characterized by the nucleation time and the aggregation rate significantly depended on the composition of the isoosmotic buffers used, and decreased in the series HEPES buffer > Tris buffer > PBS. Ferric chloride at neutral pH was converted into water-insoluble iron hydroxide III (≡FeIIIOH). According to the data of scanning electron microscopy the ≡FeIIIOH particles formed in HEPES buffer, Tris buffer, and PBS practically did not differ in structure. However, the sizes of ≡FeIIIOH floating particles measured by dynamic light scattering differed significantly and were 44 ± 28 nm, 93 ± 66 nm, 433 ± 316 nm (Zaver ± SD) for HEPES buffer, Tris buffer, and PBS, respectively. It was found by the spin trap method that the ability of ≡FeIIIOH to decompose H2O2 with the formation of a •OH decreases in the series HEPES buffer, Tris buffer, and PBS. The authors suggest that the ability to generate •OH during the decomposition of H2O2 is determined by the total surface area of ≡FeIIIOH particles, which significantly depends on the composition of the buffer in which these particles are formed.


Asunto(s)
Cristalinas , Compuestos de Hierro , HEPES/química , Trometamina , Peróxido de Hidrógeno , Estrés Oxidativo , Tampones (Química) , Oxidación-Reducción
17.
J Fluoresc ; 33(2): 601-611, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36469208

RESUMEN

Schiff base 4-((E)-((E)-(2-hydroxybenzylidene)hydrazono)methyl)-5-(hydroxymethyl)-2-methylpyridin-3-ol (HSP) was synthesized by condensing vitamin B6 cofactor pyridoxal with salicylaldehyde hydrazone, and characterized by standard spectroscopic techniques (FT-IR, 1H NMR, 13C NMR, and ESI-MS). The solution of HSP in DMSO/HEPES (10 mM, pH = 7.4) mixed solvents with varying HEPES fractions (fw) from 0 to 95% showed aggregation-induced emission (AIE). The AIE active HSP in 95% HEPES gave intense fluorescent emission at 570 nm was employed for the detection of metal ions. The fluorescence of HSP was quenched upon adding Cu2+ and Fe2+ ions. The association constant (Ka) of the Schiff base HSP with Cu2+ and Fe2+ ions was estimated as 4.08 × 105 M-1 and 1.23 × 105 M-1, respectively by using the online analysis tool BindFit v0.5. The HSP showed the detection limit down to 1.75 µM and 1.89 µM for Cu2+ and Fe2+ ions, respectively. Further, the aggregates of HSP were applied to visualize latent fingerprints (LFPs) over a non-porous glass slide.


Asunto(s)
Cobre , Piridoxal , Cobre/análisis , Colorantes Fluorescentes/química , HEPES , Iones , Imagen Óptica , Bases de Schiff/química , Espectrometría de Fluorescencia , Espectroscopía Infrarroja por Transformada de Fourier , Hierro/análisis
18.
Chemistry ; 29(2): e202202972, 2023 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-36196913

RESUMEN

We found the binding affinities of amide naphthotube to neutral organic molecules in water are not influenced by most of small biomolecules, inorganic salts, and PBS and Tris buffers but are reduced in HEPES buffer through competitive binding. Nevertheless, salts do change the binding affinities of amide naphthotube to charged molecules through a screening effect.


Asunto(s)
Amidas , Sales (Química) , Tampones (Química) , HEPES/química , Agua/química
19.
Sensors (Basel) ; 22(19)2022 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-36236234

RESUMEN

Monitoring glucose levels is important not only for diabetics, but also for tracking embryonic development in human embryo culture media. In this study, an optochemical sensor (glucose-selective polymer membrane) was fabricated for the determination of glucose in serum from diabetic patients and the culture media of human embryos. The optode membranes were formulated using polyvinyl chloride (PVC) as the polymer matrix and 4',5'-dibromofluorescein octadecyl ester (ETH 7075) as the chromoionophore. The sensitivity of the optode membranes was optimized using two different plasticizers (tricresyl phosphate-TCP and nitrophenyloctyl ether-NOPE) and three ionophores (nitrophenylboronic acid-NPBA, trifluorophenyboronic acid-TFPBA, 4'-nitrobenzo-15-crown-5) and tested for glucose detection. The best optode membrane was formulated from 49.5% PVC, 49.5% TCP, 1% NPBA, and 1% ETH 7075. It showed a linear dynamic range of 10-3 M to 10-1 M, with a detection limit of 9 × 10-4 M and a response time of 2 min. The detection mechanism involves H-bonding between NPBA and glucose, which was confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR). The reaction also involves the formation of boronate esters in basic media with deprotonation of the chromoionophore (ETH 7075), leading to a decrease in UV-Vis absorbance at λmax = 530 nm. The membrane optode was used for glucose determination in synthetic culture medium, commercial embryo culture medium (GLOBAL® TOTAL® W/HEPES), and serum from normal and diabetic patients, showing good accuracy and precision of the optode.


Asunto(s)
Diabetes Mellitus , Tritolilfosfatos , Glucemia , Automonitorización de la Glucosa Sanguínea , Ácidos Borónicos , Medios de Cultivo , Ésteres , Éteres , HEPES , Humanos , Ionóforos/química , Membranas Artificiales , Plastificantes/química , Cloruro de Polivinilo/química
20.
J Comp Eff Res ; 11(16): 1201-1217, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-36148921

RESUMEN

Aim: To explore the effectiveness of home-based exercise programs with e-devices (HEPEs) on falls among community-dwelling older adults. Methods: Twelve randomized controlled trials were included in the meta-analysis considering four fall-related outcomes. Results: HEPEs significantly reduced the rate of falls (risk ratio: 0.82; 95% CI: 0.72-0.95; p = 0.006) and improved lower extremity strength (mean difference: -0.94; 95% CI: -1.71 to -0.47; p < 0.001). There was a significant improvement favoring HEPEs on balance if the participants were aged >75 years (mean difference: -0.55; 95% CI: -1.05 to -0.05; p = 0.03), or the intervention duration was at least 16 weeks (mean difference: -0.81; 95% CI: -1.58 to -0.05; p = 0.04). Conclusion: HEPEs demonstrated an overall positive effect on falls among community-dwelling older adults.


Asunto(s)
Vida Independiente , Equilibrio Postural , Anciano , Terapia por Ejercicio , HEPES , Humanos
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