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1.
J Physiol Anthropol ; 39(1): 2, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-32019602

RESUMO

BACKGROUND: This study examined the effects of immersion in stirred, high-concentration, artificial carbonic acid water on body cooling. METHODS: Seven healthy male students (23 ± 2 years old) participated in the experiment. Signed informed consent was obtained from all subjects before the experiment. The subjects changed into shorts and T-shirts and entered an experimental room (with room temperature controlled at 30 °C and relative humidity maintained at 70%) at least 30 min before starting the experiment. After starting the experiment, the subjects were asked to rest on an exercise bike for 5 min and then pedal for 20 min. The exercise load was set to reach 50% of each subject's presumed maximum oxygen intake at 5 min after starting exercise. Subjects then continued pedaling for 1 min to cool down. After this exercise, subjects sat on a chair and immersed forearms in tap water or artificial carbonic acid water (CO2 water) at 25 °C for 20 min. During immersion, tap water or CO2 water was stirred slowly with a pump. After immersion, subjects rested for 10 min. Skin temperature and skin blood flow (left forearm), as well as heart rate and ear canal temperature, were measured continuously. Thermal sensation and thermal comfort were measured intermittently. RESULTS: Skin blood flow of the immersed forearms was higher in CO2 water than in tap water during immersion. The blood flow in the last 5 min (average at rest was 100%) was significantly higher in CO2 water (290.85 ± 84.81%) than in tap water (104.80 ± 21.99%). Thermal sensation and thermal comfort were not different between conditions. Ear canal temperature significantly declined more in CO2 water (- 0.56 ± 0.31 °C) than in tap water (- 0.48 ± 0.30 °C) during immersion. CONCLUSIONS: Our study suggests that immersion of the forearms in slowly stirred CO2 water at 25 °C reduces core temperature elevated by heat stress or exercise more effectively than does tap water at the same temperature. Immersion of the forearms in stirred CO2 water at 25 °C could be useful as a preventive measure against heat stroke from summer work or exercise.


Assuntos
Temperatura Corporal/fisiologia , Ácido Carbônico , Temperatura Baixa , Antebraço/fisiologia , Adulto , Crioterapia , Golpe de Calor , Humanos , Masculino , Pele/irrigação sanguínea , Adulto Jovem
2.
Nat Commun ; 10(1): 5262, 2019 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-31748525

RESUMO

Foreign body reaction (FBR) to implanted biomaterials and medical devices is common and can compromise the function of implants or cause complications. For example, in cell encapsulation, cellular overgrowth (CO) and fibrosis around the cellular constructs can reduce the mass transfer of oxygen, nutrients and metabolic wastes, undermining cell function and leading to transplant failure. Therefore, materials that mitigate FBR or CO will have broad applications in biomedicine. Here we report a group of zwitterionic, sulfobetaine (SB) and carboxybetaine (CB) modifications of alginates that reproducibly mitigate the CO of implanted alginate microcapsules in mice, dogs and pigs. Using the modified alginates (SB-alginates), we also demonstrate improved outcome of islet encapsulation in a chemically-induced diabetic mouse model. These zwitterion-modified alginates may contribute to the development of cell encapsulation therapies for type 1 diabetes and other hormone-deficient diseases.


Assuntos
Alginatos/química , Betaína/análogos & derivados , Encapsulamento de Células/métodos , Diabetes Mellitus Tipo 1/terapia , Reação a Corpo Estranho/prevenção & controle , Animais , Betaína/química , Ácido Carbônico , Proliferação de Células , Diabetes Mellitus Experimental , Cães , Fibrose , Transplante das Ilhotas Pancreáticas/métodos , Camundongos , Ratos , Suínos
3.
Proc Natl Acad Sci U S A ; 116(42): 20837-20843, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31570591

RESUMO

Carbonic acid H2CO3 (CA) is a key constituent of the universal CA/bicarbonate/CO2 buffer maintaining the pH of both blood and the oceans. Here we demonstrate the ability of intact CA to quantitatively protonate bases with biologically-relevant pKas and argue that CA has a previously unappreciated function as a major source of protons in blood plasma. We determine with high precision the temperature dependence of pKa(CA), pKa(T) = -373.604 + 16,500/T + 56.478 ln T. At physiological-like conditions pKa(CA) = 3.45 (I = 0.15 M, 37 °C), making CA stronger than lactic acid. We further demonstrate experimentally that CA decomposition to H2O and CO2 does not impair its ability to act as an ordinary carboxylic acid and to efficiently protonate physiological-like bases. The consequences of this conclusion are far reaching for human physiology and marine biology. While CA is somewhat less reactive than (H+)aq, it is more than 1 order of magnitude more abundant than (H+)aq in the blood plasma and in the oceans. In particular, CA is about 70× more abundant than (H+)aq in the blood plasma, where we argue that its overall protonation efficiency is 10 to 20× greater than that of (H+)aq, often considered to be the major protonating agent there. CA should thus function as a major source for fast in vivo acid-base reactivity in the blood plasma, possibly penetrating intact into membranes and significantly helping to compensate for (H+)aq's kinetic deficiency in sustaining the large proton fluxes that are vital for metabolic processes and rapid enzymatic reactions.


Assuntos
Análise Química do Sangue , Ácido Carbônico/química , Água do Mar/química , Sangue/metabolismo , Dióxido de Carbono/química , Dióxido de Carbono/metabolismo , Ácido Carbônico/metabolismo , Humanos , Hidrogênio/química , Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Hidrogenação , Cinética , Prótons
4.
Mol Pharm ; 16(6): 2626-2635, 2019 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-31013101

RESUMO

The main buffering system influencing ionizable drug dissolution in the human intestinal fluid is bicarbonate-based; however, it is rarely used in routine pharmaceutical practice due to the volatility of dissolved CO2. The typical pharmaceutical buffers used fail to capture the unique aspects of the hydration-dehydration kinetics of the bicarbonate-CO2 system. In particular, CO2 is involved in a reversible interconversion with carbonic acid (H2CO3), which is the actual conjugate acid of the system, as follows CO2 + H2O ⇌ H2CO3. In contrast to ionization reactions, this interconversion does not equilibrate very rapidly compared to the diffusional processes through a typical fluid diffusion boundary layer at a solid-liquid interface. In this report, a mathematical mass transport analysis was developed for ionizable drug dissolution in bicarbonate using the rules of conservation of mass and electric charge in addition to accounting for the diffusional times and reaction rate constants of the CO2-H2CO3 interconversion. This model, which includes both the hydration reaction rate and dehydration reaction rate, we called the "reversible non-equilibrium" (RNE) model. The predictions made by this RNE approach for ionizable drug dissolution rates were compared to the experimental data generated by an intrinsic dissolution method for three ionizable drugs, indomethacin, ibuprofen, and haloperidol. The results demonstrate the superiority of predictions for the RNE approach compared to the predictions of a model assuming equilibrium between CO2 and H2CO3, as well as models ignoring reactions. The analysis also shows that bicarbonate buffer can be viewed as having an effective p Ka in the boundary layer that is different from that in bulk and is hydrodynamics-dependent.


Assuntos
Bicarbonatos/química , Dióxido de Carbono/química , Ácido Carbônico/química , Concentração de Íons de Hidrogênio , Cinética
5.
Plant J ; 96(5): 1018-1035, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30203878

RESUMO

Respiration in leaves and the continued elevation in the atmospheric CO2 concentration cause CO2 -mediated reduction in stomatal pore apertures. Several mutants have been isolated for which stomatal responses to both abscisic acid (ABA) and CO2 are simultaneously defective. However, there are only few mutations that impair the stomatal response to elevated CO2 , but not to ABA. Such mutants are invaluable in unraveling the molecular mechanisms of early CO2 signal transduction in guard cells. Recently, mutations in the mitogen-activated protein (MAP) kinase, MPK12, have been shown to partially impair CO2 -induced stomatal closure. Here, we show that mpk12 plants, in which MPK4 is stably silenced specifically in guard cells (mpk12 mpk4GC homozygous double-mutants), completely lack CO2 -induced stomatal responses and have impaired activation of guard cell S-type anion channels in response to elevated CO2 /bicarbonate. However, ABA-induced stomatal closure, S-type anion channel activation and ABA-induced marker gene expression remain intact in the mpk12 mpk4GC double-mutants. These findings suggest that MPK12 and MPK4 act very early in CO2 signaling, upstream of, or parallel to the convergence of CO2 and ABA signal transduction. The activities of MPK4 and MPK12 protein kinases were not directly modulated by CO2 /bicarbonate in vitro, suggesting that they are not direct CO2 /bicarbonate sensors. Further data indicate that MPK4 and MPK12 have distinguishable roles in Arabidopsis and that the previously suggested role of RHC1 in stomatal CO2 signaling is minor, whereas MPK4 and MPK12 act as key components of early stomatal CO2 signal transduction.


Assuntos
Proteínas de Arabidopsis/fisiologia , Proteínas Quinases Ativadas por Mitógeno/fisiologia , Estômatos de Plantas/fisiologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Ácido Carbônico/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Estômatos de Plantas/metabolismo , Transdução de Sinais
6.
J Mech Behav Biomed Mater ; 87: 148-154, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30071485

RESUMO

Over the past years, significant effort has been dedicated to synthesizing low-shrinking formulations, however, development of dental composites with low volumetric shrinkage continues to be challenging. The purpose of this study was to synthesize a bisphenol allylic derivate (BPhADAC) and evaluate its inclusion in the formulation of a photopolymerizable dental composite resin, as a BisGMA diluent. Experimental (BisGMA/BPhADAC) and control (BisGMA/TEGDMA) photopolymerizable composites were prepared. Double bond conversion, polymerization kinetics, volumetric shrinkage, water sorption, solubility, and flexural properties were investigated. The experimental composite showed higher degree of conversion values, less volumetric shrinkage and less water sorption than the control composite (p < 0.05). In addition, flexural strength between the materials was found to be similar. The overall properties prove that the allylic monomer BPhADAC could be potentially useful in the formulation of low-shrinking dental composite resins.


Assuntos
Resinas Acrílicas/química , Ácido Carbônico/química , Ácido Carbônico/síntese química , Resinas Compostas/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Poliuretanos/química , Resinas Acrílicas/toxicidade , Animais , Bis-Fenol A-Glicidil Metacrilato/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Técnicas de Química Sintética , Cor , Resinas Compostas/toxicidade , Composição de Medicamentos , Módulo de Elasticidade , Resistência à Flexão , Cinética , Camundongos , Processos Fotoquímicos , Polimerização , Poliuretanos/toxicidade , Solubilidade , Água/química
7.
PLoS One ; 13(7): e0200012, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29966023

RESUMO

A natural pH gradient caused by marine CO2 seeps off the Methana peninsula (Saronikos Gulf, eastern Peloponnese peninsula) was used as a natural laboratory to assess potential effects of ocean acidification on coccolithophores. Coccolithophore communities were therefore investigated in plankton samples collected during September 2011, September 2016 and March 2017. The recorded cell concentrations were up to ~50 x103 cells/l, with a high Shannon index of up to 2.8, along a pH gradient from 7.61 to 8.18, with values being occasionally <7. Numerous holococcolithophore species represented 60-90% of the surface water assemblages in most samples during September samplings. Emiliania huxleyi was present only in low relative abundances in September samples, but it dominated in March assemblages. Neither malformed nor corroded coccolithophores were documented. Changes in the community structure can possibly be related to increased temperatures, while the overall trend associates low pH values with high cell densities. Our preliminary results indicate that in long-termed acidified, warm and stratified conditions, the study of the total coccolithophore assemblage may prove useful to recognize the intercommunity variability, which favors the increment of lightly calcified species such as holococcolithophores.


Assuntos
Dióxido de Carbono/farmacologia , Haptófitas/efeitos dos fármacos , Dióxido de Carbono/química , Ácido Carbônico/química , Ácido Carbônico/farmacologia , Clorofila A/metabolismo , Mudança Climática , Grécia , Haptófitas/crescimento & desenvolvimento , Haptófitas/metabolismo , Concentração de Íons de Hidrogênio , Mar Mediterrâneo , Nutrientes/farmacologia , Salinidade , Temperatura
8.
J Chromatogr A ; 1557: 90-98, 2018 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-29748093

RESUMO

EXPERIMENTAL: and theoretical studies were conducted to investigate low and non-linear responses in sub-micro molar-level suppressed ion chromatography with a hydroxide eluent. A calculated response was derived using experimentally determined detector effluent ion composition data and compared with measured experimental responses. The calibration curve was non-linear, and its slope varied considerably with different instrumental setups and operating conditions. The non-linearity of the solution conductivity response was determined by two acid-base equilibria of water and carbonic acid, and fluoride ion. By using eluent contaminated with para-toluene sulfonate at micro molar level, the non-linear response was greatly alleviated.


Assuntos
Cromatografia por Troca Iônica/métodos , Hidróxidos/análise , Benzenossulfonatos/química , Calibragem , Ácido Carbônico/química , Cromatografia por Troca Iônica/normas , Fluoretos/química , Hidróxidos/isolamento & purificação , Hidróxidos/normas , Limite de Detecção , Água/química
9.
Carbohydr Res ; 455: 97-105, 2018 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-29195134

RESUMO

Alpha and beta-glucoisosaccharinic acids ((2S,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid and (2R,4S)-2,4,5-trihydroxy-2-(hydroxymethyl)pentanoic acid) which are produced when cellulosic materials are treated with aqueous alkali are potentially valuable platform chemicals. Their highly functionalised carbon skeleton, with fixed chirality at C-2 and C-4, makes them ideal starting materials for use in synthesis. In order to assess the potential of these saccharinic acids as platform chemicals we have explored the protecting group chemistry of the lactone form of alpha-glucoisosaccharinic acid (α-GISAL). We report here the use of single and multiple step reaction pathways leading to the regioselective protection of the three different hydroxyl groups of α-GISAL. We report strategies for protecting the three different hydroxyl groups individually or in pairs. We also report the synthesis of a range of tri-O-protected α-GISAL derivatives where a number of the products contain orthogonal protecting groups.


Assuntos
Ácido Carbônico/química , Açúcares Ácidos/química , Estereoisomerismo
10.
J Chromatogr A ; 1530: 176-184, 2017 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-29162234

RESUMO

During a preparative separation of the cis enantiomeric pair of benzyl-2,3-dihydroxypiperidine-1-carboxylate using supercritical-fluid chromatography (SFC) with methanol modifier, significant degradation of the products in the collected fractions was observed when a Waters SFC-350® (Milford, MA, USA) was used, but same was not observed when a Waters SFC-80q® (Milford, MA, USA) was used. Through a systematic investigation, we discovered that the compound degraded over time under an acidic condition created by the formation of methyl carbonic acid from methanol and CO2. The extent of the product degradation was dependent on the time and the concentration of CO2 remained in the product fraction, which was governed by the efficiency of CO2-methanol separation during the fraction collection. Hence, we demonstrated that the different designs of CO2-solvent separator (high pressurized cyclone in Waters SFC-350® and low-pressurized vortexing separator in Waters SFC-80q®®) had a significant impact on the degradation of an acid-sensitive compound. The acidity caused by CO2 in methanol was supported by diminished degradation after a nitrogen purging or after neutralizing the collected fractions with a base. Three different solutions to overcome the degradation problem of the acid sensitive compounds using SFC-350® with the high pressurized separator were investigated and demonstrated. The degraded products were isolated as four enantiomers and their relative stereochemistry were established based on 2D NMR data along with the plausible mechanism of degradation.


Assuntos
Dióxido de Carbono/química , Ácidos Carboxílicos/química , Cromatografia com Fluido Supercrítico , Solventes/química , Ácido Carbônico/química , Metanol/química , Piperidinas/química , Pressão , Estereoisomerismo
11.
J Chromatogr A ; 1523: 300-308, 2017 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-28549716

RESUMO

Conductometric ion exclusion chromatography of weak acids does not enjoy the same degree of success as its counterpart in suppressed conductometric anion exchange chromatography. Compared to the latter, eluent preparation is not automated. Commonly, a strong acid is used as the eluent leading to a relatively high-detector background and poorer limits of detection. In addition, generally applicable gradient elution has not been possible. We introduce the automated preparation of carbonic acid eluents at concentrations exceeding 0.15M by introducing CO2 into a flowing water stream through the walls of a Teflon AF® capillary tube under pressure; the resulting eluent concentration is controlled by varying the CO2 pressure in a programmed manner. The acidic carbonic acid solution functions as the eluent and can be almost completely removed (detector background 1.2-1.6µS/cm) by an improved carbon dioxide removal device before detection. Theoretical and practical considerations are discussed and illustrative isocratic and gradient ion exclusion chromatography is demonstrated.


Assuntos
Ácidos/isolamento & purificação , Ácido Carbônico/química , Técnicas de Química Analítica/métodos , Cromatografia em Gel , Técnicas de Química Analítica/instrumentação , Cromatografia em Gel/instrumentação , Compostos Orgânicos/isolamento & purificação
12.
Prog Mol Subcell Biol ; 55: 221-257, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28238040

RESUMO

Based on evolution of biomineralizing systems and energetic considerations, there is now compelling evidence that enzymes play a driving role in the formation of the inorganic skeletons from the simplest animals, the sponges, up to humans. Focusing on skeletons based on calcium minerals, the principle enzymes involved are the carbonic anhydrase (formation of the calcium carbonate-based skeletons of many invertebrates like the calcareous sponges, as well as deposition of the calcium carbonate bioseeds during human bone formation) and the alkaline phosphatase (providing the phosphate for bone calcium phosphate-hydroxyapatite formation). These two enzymes, both being involved in human bone formation, open novel not yet exploited targets for pharmacological intervention of human bone diseases like osteoporosis, using compounds that act as activators of these enzymes. This chapter focuses on carbonic anhydrases of biomedical interest and the search for potential activators of these enzymes, was well as the interplay between carbonic anhydrase-mediated calcium carbonate bioseed synthesis and metabolism of energy-rich inorganic polyphosphates. Beyond that, the combination of the two metabolic products, calcium carbonate and calcium-polyphosphate, if applied in an amorphous form, turned out to provide the basis for a new generation of scaffold materials for bone tissue engineering and repair that are, for the first time, morphogenetically active.


Assuntos
Fosfatase Alcalina/metabolismo , Desenvolvimento Ósseo/efeitos dos fármacos , Osso e Ossos/enzimologia , Carbonato de Cálcio/metabolismo , Fosfatos de Cálcio/metabolismo , Anidrases Carbônicas/metabolismo , Fosfatase Alcalina/efeitos dos fármacos , Animais , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Osso e Ossos/efeitos dos fármacos , Ácido Carbônico/metabolismo , Anidrases Carbônicas/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos/tendências , Ativação Enzimática/efeitos dos fármacos , Humanos , Poríferos/química
13.
Electrophoresis ; 38(5): 677-688, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27699824

RESUMO

This paper comprises a continuation of computer simulation studies dealing with carrier ampholyte based CIEF in presence of narrow pH gradients. With this technique, amphoteric sample components with pI values outside the pH gradient are migrating isotachophoretically toward the cathode or anode whereas components with pI values within the gradient become focused. In order to understand the processes occurring in presence of the electric field, the behavior of both carrier ampholytes and amphoteric sample components is investigated by computer modeling. Characteristics of two pH unit gradients with end components having pI values at or around 7.00 and conditions that lead to the formation of a water zone at neutrality were investigated. Data obtained reveal that a zone of water is formed in focusing with carrier ampholytes when the applied pH range does not cover the neutral region, ends at pH 7.00 or begins at pH 7.00. The presence of additional amphoteric components that cover the neutrality region prevent water zone formation under current flow. This situation is met in experiments with narrow pH gradients that end or begin around neutrality. Simulation data reveal that no water zone evolves when atmospheric carbon dioxide dissolved in the catholyte causes the migration of carbonic acid (in the form of carbonate and/or hydrogen carbonate ions) from the catholyte through the focusing structure. An electrolyte change in the electrode solution does not have an impact on the focusing part but does change the isotachophoretic pattern migrating behind the leading ion.


Assuntos
Misturas Anfolíticas/química , Eletroforese Capilar/métodos , Focalização Isoelétrica/métodos , Ácido Carbônico/química , Simulação por Computador , Concentração de Íons de Hidrogênio , Água/química
14.
J Contemp Dent Pract ; 17(7): 568-73, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27595724

RESUMO

INTRODUCTION: In this in vitro study, the efficacy of 2% carbonic acid and 2% acetic acid on the surface, microhardness of white mineral trioxide aggregate (MTA) and dentin after 1 day of setting and 21 days of setting of MTA is measured. MATERIALS AND METHODS: Tooth molds were made using 60 single-rooted premolars by slicing them to 4 mm in the mid-root region. White MTA (Angelus) was mixed and packed in the molds. Three experimental groups were formed and exposed to 2% carbonic acid, 2% acetic acid, and saline for 10 minutes on 1 and 21 days of setting respectively. Vickers hardness test of white MTA and dentin was done before and after exposure. Data were subjected to analysis of variance (ANOVA) and post hoc tests. RESULTS: The results show that 2% acetic acid was significantly effective in reducing the microhardness of white MTA compared to 2% carbonic acid and saline on exposure for 10 minutes. CONCLUSION: The results of the present study indicate that 2% acetic acid has maximum efficacy in reducing the surface microhardness of partial and completely set MTA, followed by 2% carbonic acid. CLINICAL SIGNIFICANCE: The following study will help find an adjunct for retrieval of MTA, which was found difficult with the existing methods.


Assuntos
Ácido Acético/química , Compostos de Alumínio/química , Compostos de Cálcio/química , Ácido Carbônico/química , Dentina/efeitos dos fármacos , Óxidos/química , Materiais Restauradores do Canal Radicular/química , Silicatos/química , Dente Pré-Molar , Combinação de Medicamentos , Dureza , Técnicas In Vitro , Propriedades de Superfície
15.
Scand J Clin Lab Invest ; 76(7): 520-543, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27410514

RESUMO

The approach to acid-base chemistry in medicine includes several methods. Currently, the two most popular procedures are derived from Stewart's studies and from the bicarbonate/BE-based classical formulation. Another method, unfortunately little known, follows the Kildeberg theory applied to acid-base titration. By using the data produced by Dana Atchley in 1933, regarding electrolytes and blood gas analysis applied to diabetes, we compared the three aforementioned methods, in order to highlight their strengths and their weaknesses. The results obtained, by reprocessing the data of Atchley, have shown that Kildeberg's approach, unlike the other two methods, is consistent, rational and complete for describing the organ-physiological behavior of the hydrogen ion turnover in human organism. In contrast, the data obtained using the Stewart approach and the bicarbonate-based classical formulation are misleading and fail to specify which organs or systems are involved in causing or maintaining the diabetic acidosis. Stewart's approach, despite being considered 'quantitative', does not propose in any way the concept of 'an amount of acid' and becomes even more confusing, because it is not clear how to distinguish between 'strong' and 'weak' ions. As for Stewart's approach, the classical method makes no distinction between hydrogen ions managed by the intermediate metabolism and hydroxyl ions handled by the kidney, but, at least, it is based on the concept of titration (base-excess) and indirectly defines the concept of 'an amount of acid'. In conclusion, only Kildeberg's approach offers a complete understanding of the causes and remedies against any type of acid-base disturbance.


Assuntos
Cetoacidose Diabética/sangue , Cetoacidose Diabética/urina , Eletrólitos , Rim/metabolismo , Prótons , Equilíbrio Ácido-Base , Bicarbonatos/sangue , Bicarbonatos/urina , Gasometria , Ácido Carbônico/sangue , Ácido Carbônico/urina , Cetoacidose Diabética/história , Cetoacidose Diabética/fisiopatologia , Eletrólitos/sangue , Eletrólitos/urina , História do Século XX , História do Século XXI , Humanos , Concentração de Íons de Hidrogênio , Hidróxidos/sangue , Hidróxidos/urina , Rim/fisiopatologia
16.
J Adhes Dent ; 18(4): 325-30, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27419241

RESUMO

PURPOSE: To examine whether a difference exists between the in vivo biocompatibility of glass-ionomer cements (GICs) containing chlorhexidine (CHX) in different concentrations. MATERIALS AND METHODS: Eighty-four male Wistar rats were distributed into 7 groups (n = 12) and received subcutaneous implants of small tubes containing different materials, as follows: Ketac control (K), Ketac-CHX 10% (K10), Ketac-CHX 18% (K18), Resilience control (R), Resilience-CHX 10% (R10), Resilience-CHX 18% (R18), Control (polyethylene). The animals were then sacrificed on post-insertion days 7, 15 and 30, and tissues were examined under an optical microscope for inflammatory infiltrate, edema, necrosis, granulation tissue, multinucleated giant cells, and collagen fibers. The results were statistically analyzed using Kruskal-Wallis and Dunn's tests (p < 0.05). RESULTS: Groups K18 and R18 showed larger areas of intense inflammatory infiltrate, with significant differences between group C and groups K18 and R18 (p = 0.007) at 7 days, and between groups C and K18 (p = 0.017) at 15 days. In terms of tissue repair, groups K18 and R18 demonstrated a lower quantity of collagen fibers with significant differences from group C (p = 0.019) at 7 days, and between group K18 and group C (p = 0.021) at 15 days. CONCLUSION: The 18% concentration of CHX was shown to have a toxic effect. The 10% concentration of CHX was shown to be suitable for tissue contact. The addition of CHX to the glass-ionomer cements is a highly promising method for obtaining of an antibacterial GIC for use in clinical practice.


Assuntos
Anti-Infecciosos Locais/administração & dosagem , Materiais Biocompatíveis/toxicidade , Clorexidina/administração & dosagem , Cimentos de Ionômeros de Vidro/toxicidade , Resinas Acrílicas/química , Resinas Acrílicas/toxicidade , Animais , Anti-Infecciosos Locais/química , Anti-Infecciosos Locais/toxicidade , Materiais Biocompatíveis/química , Ácido Carbônico/química , Ácido Carbônico/toxicidade , Clorexidina/química , Clorexidina/toxicidade , Colágeno/efeitos dos fármacos , Materiais Dentários/química , Materiais Dentários/toxicidade , Edema/induzido quimicamente , Fibroblastos/efeitos dos fármacos , Células Gigantes/efeitos dos fármacos , Cimentos de Ionômeros de Vidro/química , Tecido de Granulação/efeitos dos fármacos , Óxido de Magnésio/química , Óxido de Magnésio/toxicidade , Masculino , Teste de Materiais , Necrose , Cimento de Policarboxilato/química , Cimento de Policarboxilato/toxicidade , Polietileno/química , Distribuição Aleatória , Ratos , Tela Subcutânea/efeitos dos fármacos , Óxido de Zinco/química , Óxido de Zinco/toxicidade
17.
Carbohydr Res ; 428: 18-22, 2016 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-27111726

RESUMO

Hemiesters of carbonic acid can be freely formed in aqueous media containing HCO3(-)/CO2 and mono- or poly-hydroxy compounds. Herein, (13)C NMR spectroscopy was used to identify isomers formed in aqueous solutions of glycerol (a prototype compound) and seven carbohydrates, as well as to estimate the equilibrium constant of formation (Keq). Although both isomers are formed, glycerol 1-carbonate corresponds to 90% of the product. While fructose and ribose form an indistinct mixture of isomers, the anomers of d-glucopyranose 6-carbonate correspond to 74% of the eight isomers of glucose carbonate that were detected. The values of Keq for the disaccharides sucrose (4.3) and maltose (4.2) are about twice the values for the monosaccharides glucose (2.0) and fructose (2.3). Ribose (Keq = 0.89)-the only sugar without a significant concentration of a species containing a -CH2OH group in an aqueous solution-resulted in the smallest Keq. On the basis of the Keq value and the concentrations of HCO3(-) and glucose in blood, one can anticipate a concentration of 2-4 µmol L(-1) for glucose 6-carbonate, which corresponds to ca. of 10% of its phosphate counterpart (glucose 6-phosphate).


Assuntos
Carboidratos/química , Ácido Carbônico/química , Ésteres/síntese química , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13/métodos , Ésteres/química , Glicerol/química , Isomerismo , Estrutura Molecular , Água/química
18.
Huan Jing Ke Xue ; 37(1): 123-31, 2016 Jan 15.
Artigo em Chinês | MEDLINE | ID: mdl-27078949

RESUMO

The observation and sampling were carried out in May 2013 to April 2014 in a hydrological year for two river basins with different geological background in upstream of Li river basin. The seasonal variations of river water chemistry and its main influencing factors were discussed in this paper. The results showed that the hydrochemistry types of both Darongjiang basin with 9% of carbonates and Lingqu basin with nearly 50% of carbonates in area belonged to Ca-HCO3 type. Ca2+ and HCO3- were the main cations and anions. The main ion concentrations were higher in winter and lower in summer, affected by the change of the flow. Ca2+, Mg2+, HCO3- were mainly sourced from the weathering of carbonates by carbonic acid. The weathering of carbonates by sulfuric acid and the weathering of silicate rocks also had contribution to the river water chemistry. In addition, comparing to the Lingqu basin, the contribution of the weathering of carbonates was much more than the percent of carbonates area, because the carbonate rocks were eroded by the allogenic water. On the other hand, K+, Na+, Cl-, NO3-, SO4(2-) were mainly affected by the atmospheric precipitation and human activities. Comparing to the Darongjiang Basin, the effects of human activities on the changes of K+, Na+, Cl-, NO3-, SO4(2-) were more significant in Lingqu Basin.


Assuntos
Carbonatos/análise , Monitoramento Ambiental , Rios/química , Estações do Ano , Ácido Carbônico/análise , China , Geologia , Hidrologia , Ácidos Sulfúricos/análise , Tempo (Meteorologia)
20.
J Phys Chem B ; 120(9): 2281-90, 2016 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-26876428

RESUMO

The protonation of methylamine base CH3NH2 by carbonic acid H2CO3 within a hydrogen (H)-bonded complex in aqueous solution was studied via Car-Parrinello dynamics in the preceding paper (Daschakraborty, S.; Kiefer, P. M.; Miller, Y.; Motro, Y.; Pines, D.; Pines, E.; Hynes, J. T. J. Phys. Chem. B 2016, DOI: 10.1021/acs.jpcb.5b12742). Here some important further details of the reaction path are presented, with specific emphasis on the water solvent's role. The overall reaction is barrierless and very rapid, on an ∼100 fs time scale, with the proton transfer (PT) event itself being very sudden (<10 fs). This transfer is preceded by the acid-base H-bond's compression, while the water solvent changes little until the actual PT occurrence; this results from the very strong driving force for the reaction, as indicated by the very favorable acid-protonated base ΔpKa difference. Further solvent rearrangement follows immediately the sudden PT's production of an incipient contact ion pair, stabilizing it by establishment of equilibrium solvation. The solvent water's short time scale ∼120 fs response to the incipient ion pair formation is primarily associated with librational modes and H-bond compression of water molecules around the carboxylate anion and the protonated base. This is consistent with this stabilization involving significant increase in H-bonding of hydration shell waters to the negatively charged carboxylate group oxygens' (especially the former H2CO3 donor oxygen) and the nitrogen of the positively charged protonated base's NH3(+).


Assuntos
Ácido Carbônico/química , Solventes/química , Água/química , Ligação de Hidrogênio , Prótons
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