Acid-base Balance Research Articles

DEVELOPMENT AND VALIDATION OF THE QUANTITATIVE DETERMINATION METHOD FOR A NEW BIOLOGICALLY ACTIVE COMPOUND N-[2-[4-OXO-3(4Н)-QINAZOLINYL]PROPIONYL]-GUANIDINE BY THE METHOD OF TITRATION IN A NON-AQUEOUS MEDIUM

Relevance. Due to the wide spread of diseases of the cardiovascular system, the development and study of drugs aimed at the treatment of diseases of the circulatory system is relevant. A new biologically active compound (BAC) is synthesized at the Department of Pharmaceutical and Toxicological Chemistry of the Volgograd State Medical University – a derivative of quinazoline: N-[2-[4-oxo-3(4H)-quinazolinyl] propionyl]-guanidine (VMA-13-15), which at the stage of preclinical studies confirmed the prospects for use in medical practice as a cardioprotective and neuroprotective drug. The aim of the study is to develop and validate a method for the quantitative determination of N-[2-[4-oxo-3(4H)-quinazolinyl]propionyl]-guanidine (VMA-13-15). Material and methods. The objects of study are laboratory samples of N-[2-[4-oxo-3(4H)-quinazolinyl]propionyl]-guanidine (VMA-13-15, series 2019, 2020 and 2021). A laboratory sample VMA-13-15 twice recrystallized from methanol and dried to constant weight is used as a standard sample (RS). Quantitative determination is carried out by acid-base titration in a non-aqueous medium. The end of the titration is fixed potentiometrically. Results. The ionization constants VMA-13-15 are determined. A procedure is developed for the quantitative determination of N-[2-[4-oxo-3(4H)-quinazolinyl]propionyl]guanidine by acid-base titration in a solvent medium of glacial acetic acid with the establishment of an equivalence point using a potentiometer. The developed method is validated according to the main characteristics: specificity, linearity, correctness, convergence and analytical area. The validation analysis of the developed method confirms that it is suitable for the quantitative determination of the main substance content in the VMA-13-15 substance. Conclusions. A technique for potentiometric titration of N-[2-[4-oxo-3(4H)-quinazolinyl]propionyl]guanidine in a non-aqueous medium is developed and validated.

Protolytic and Complexing Properties of Isomeric N-(Pyridylethyl)taurines

New N-derivatives of taurine, N-[2-(2-pyridyl)ethyl]taurine (HL1) and N-[2-(4-pyridyl)ethyl]taurine (HL2) have been synthesized. Using the method of alkalimetric titration of aqueous solutions with pH potentiometric indication at I = 0.1 mol/L (KCl/KNO3) and T = 25 ± 1°C, the acid dissociation constants of functional groups in the composition of reagents have been determined (HL1: pKa0 = 3.80 ± 0.03, pKa1 = 8.67 ± 0.02, HL2: pKa0 = 4.80 ± 0.05, pKa1 = 8.18 ± 0.04). It has been found that reagent HL1 is more resistant to the degradation process. The complexation of transition and alkaline earth metal ions with НL1 has been studied. It has been shown that the introduction of a 2-(2-pyridyl)ethyl substituent into the structure of taurine leads to a significant increase in the stability (Δ log β ≥ 1) of copper(II), cobalt(II), nickel(II), zinc(II), cadmium(II) and silver(I) complexes with НL1. Calcium(II), magnesium(II), strontium(II), and barium(II) complexes with HL1 are characterized by a slight increase in stability (Δ lg β 1) compared to taurine. Based on the data obtained, the structure of the studied complexes have been assumed.

Sodium Bicarbonate and Time-to-Exhaustion Cycling Performance: A Retrospective Analysis Exploring the Mediating Role of Expectation

BackgroundResearch has shown that ingesting 0.3 g·kg−1 body mass sodium bicarbonate (NaHCO3) can improve time-to-exhaustion (TTE) cycling performance, but the influence of psychophysiological mechanisms on ergogenic effects is not yet understood.ObjectiveThis study retrospectively examined whether changes in TTE cycling performance are mediated by positive expectations of receiving NaHCO3 and/or the decline in blood bicarbonate during exercise.MethodsIn a randomised, crossover, counterbalanced, double-blind, placebo-controlled design, 12 recreationally trained cyclists (maximal oxygen consumption, 54.4 ± 5.7 mL·kg·min−1) performed four TTE cycling tests 90 min after consuming: (1) 0.3 g·kg−1 body mass NaHCO3 in 5 mL·kg−1 body mass solution, (2) 0.03 g·kg−1 body mass sodium chloride in solution (placebo), (3) 0.3 g·kg−1 body mass NaHCO3 in capsules and (4) cornflour in capsules (placebo). Prior to exercise, participants rated on 1–5 Likert type scales how much they expected the treatment they believe had been given would improve performance. Capillary blood samples were measured for acid-base balance at baseline, pre-exercise and post-exercise.ResultsAdministering NaHCO3 in solution and capsules improved TTE compared with their respective placebos (solution: 27.0 ± 21.9 s, p = 0.001; capsules: 23.0 ± 28.1 s, p = 0.016). Compared to capsules, NaHCO3 administered via solution resulted in a higher expectancy about the benefits on TTE cycling performance (Median: 3.5 vs. 2.5, Z = 2.135, p = 0.033). Decline in blood bicarbonate during exercise was higher for NaHCO3 given in solution compared to capsules (2.7 ± 2.1 mmol·L−1, p = 0.001). Mediation analyses showed that improvements in TTE cycling were indirectly related to expectancy and decline in blood bicarbonate when NaHCO3 was administered in solution but not capsules.ConclusionsParticipants’ higher expectations when NaHCO3 is administered in solution could result in them exerting themselves harder during TTE cycling, which subsequently leads to a greater decline in blood bicarbonate and larger improvements in performance.Key PointsIngesting 0.3 g·kg−1 body mass sodium bicarbonate in solution and capsules improved time-to-exhaustion cycling performancePositive expectancy about the benefits of sodium bicarbonate and decline in blood bicarbonate were higher when sodium bicarbonate was administered in solution compared with capsulesImprovements in time-to-exhaustion cycling performance for sodium bicarbonate administered in solution were related to expectancy and the enhanced extracellular buffering response

Mineral evolution mechanism of Zinc-slag during high-temperature reactive process

The mineral transformation mechanism, microstructure evolution and chemical reactivity of Zinc-slag sintered at 1350–1550 °C for 10–60 min were systematically studied using Fe2O3, Al2O3, SiO2, CaO, MgO and ZnO as raw simulation materials. The molar ratio, sintering temperature and duration could affect the ions diffusion and migration in molten state attributing to the acid-base equilibrium and the energy of atomic thermal motion, and then influence the phase formation and transition process. Meanwhile, the FactSage software was used to calculate the equilibrium polyphase diagram for predicting the phase transformation mechanism of non-equilibrium system, while the Si4+ and Al3+ react with Ca2+ easily due to the tetrahedral structure. The phase composition of Zinc-slag contains Ca2Al2SiO7, Ca3(Si3O9), ZnFe2O4, Fe2O3, SiO2 and Fe when sintered at 1500 °C for 60 min, and it also has the optimal Zinc recovery efficiency of 91% with 1.2 mol/L H2SO4 and 0.04 mol/L H2S2O8 attributing to the large layer spacing and uniform distribution of ZnFe2O4. The lime sinter process with acid-leaching technology is beneficial to effectively improve the utilization rate of Zinc-slag, and it also could provide a strategy to solve the environmental pollution problem caused by industrial waste slag.

Green removal of low and high levels of Cu(II) and Cr(III) cations from concentrated saline chloride medium achieved by a mixture of N,N′-bis(salicylidene)-thiocarbohydrazide-TritonX-100 micellar system via cloud point extraction process

Abstract In this work, we performed the cloud point extraction with low and high concentrations of Cu(II) and Cr(III), two particularly toxic metallic pollutants, that have been shown to have adverse effects on human health and the environment. Removal of the metal ions was achieved in the presence of Triton X-100 as a non-ionic surfactant and N,N′-bis(salicylidene)-thiocarbohydrazide as a chelating ligand in concentrated chloride medium. The behavior of the Schiff base was initially investigated in homogeneous DMSO-water and micellar Triton X-100-water media. The obtained values of the acid constants show that the extractant is more acidic in micellar media than in pure aqueous medium. The recorded cloud point temperatures of Triton X-100 are significantly impacted by the sodium chloride concentration, the surfactant concentration, and the Schiff base ligand. Under the optimised experimental conditions, a quantitative extraction of Cu(II) and a maximum extraction rate of 74 % of Cr(III) were obtained. The reduction of the metal concentration from 10−3 mol L−1 to 10−6 mol L−1 resulted in a reduction of the temperature by 10 °C and a reduction of the contact time from 10 h to 3 h.

Clinical application of ozone therapy, ultrasound and cryotherapy in the treatment of infected and purulent wounds on the background of chronic venous insufficiency

Research objective: To think up and estimate efficiency of the combined ozonoterapiya at treatment it is long not healing and purulent wounds which have developed against the background of chronic venous insufficiency. Materials and methods: Clinical trial has included 134 patients with chronic venous insufficiency with are long not healing purulent wounds. In a zavisismost from the chosen treatment method patients are divided into three groups. Groups were comparable on a sex, age and weight of defeat of soft fabrics. Assessment of efficiency of treatment was carried out by results of planimetry of wounds, an acid-base condition of a wound and speed of a blood-groove on border of healthy fabric and a wound. Results: On the basis of the conducted researches have proved efficiency of the combined treatment with use of a system and local ozonoterapiya, cryogenic stimulation and ultrasound. The developed algorithm of maintaining patients with chronic venous insufficiency with it is long nekhazhivayushchy wounds, reduces a painful interval to (3,1 0,6) days, accelerates filling of wounds with granulations and emergence of a regional epitalization which appeared to (6,2 1,1) days. The developed technique of a complex ozonoterapiya normalizes blood-groove speed on border of healthy fabric and a wound and restores acid-base balance. Use of a new medical complex reduces stay of patients in a hospital by 17,4 % and reduces disability terms by 12,8 %. Conclusion: At patients with the chronic venous insufficiency complicated it is long not healing infected wounds, use of the new technologies including a local and system ozonoterapiya, cryotherapy and ultrasound is expedient.

Predicting the removal efficiency of pharmaceutical and personal care products using heated metal oxides as adsorbents based on their physicochemical characteristics

Pharmaceutical and personal care products (PPCPs) are emerging pollutants that are commonly found in the environment and exist predominantly in nondegradable forms. Several attempts have been made to remove PPCPs via conventional wastewater treatment processes; however, these processes have limitations, such as high costs and insufficient removal efficiencies. Adsorption is a promising alternative for removing PPCPs because it is inexpensive, highly reusable, and easy to operate. Therefore, this study aims to determine the contributing characteristics that can be used to predict the adsorption behaviour of PPCPs based on their physicochemical properties, with heated metal oxide adsorbents (HMOAs). HAOP (heated aluminium oxide particles) and HIOP (heated iron oxide particles) with particle sizes below 38 μm were used. Results from the Brunauer-Emmett-Teller (BET) analysis show that HIOP has higher surface area and smaller pore size (113.7 ± 26.3 m2/g and 5.4 ± 1.8 nm) than HAOP (14.5 ± 0.6 m2/g and 18.6 ± 3.1 nm), which suggest that HIOP would show superior adsorption rates compared to HAOP. The adsorption mechanism is identified based on three major physicochemical properties of PPCPs: molecular weight (M.W.), octanol–water partition coefficient (log Kow), and acid dissociation constant (pKa). The results suggest that the most dominant factor that contributes to the adsorption of PPCPs on to HMOAs is the M.W., where the larger the molecular size, the better the adsorption efficiency. The tests conducted with varying log Kow values revealed that the hydrophilicity of the adsorbent influences the adsorption performance. It was found that HIOP exhibits better removal efficiencies with hydrophilic PPCPs (up to 83%) than with hydrophobic PPCPs (48%), while HAOP exhibits better removal efficiencies with hydrophobic PPCPs (86%) than with hydrophilic PPCPs, with less than 10% removal. Unlike the M.W. and pKa values, the log Kow does not exhibit any visible trend. Therefore, the adsorption behaviour can be predicted with the M.W. and pKa values of the PPCPs, when HAOP and HIOP are used as adsorbents.

High-throughput and reliable assessments of the ionization constant of monoprotic organic acids through an arginine based mixed mode HPLC

The charge state of a molecule is the single most prominent attribute ruling out its interactions with the surrounding environment. In a previous study, the retention of acids on the new Celeris™ Arginine (ARG) column was found to be predominantly driven by electrostatics and, specifically, their charge state. Therefore, we analysed 41 compounds in liquid chromatography with ultraviolet detection to study possible relationships between the analytical retention on this phase and the pKa of the acidic solutes. Highly significant relationships were observed indicating either a linear (r2 = 0.86) or a quadratic (r2= 0.89) trend. To improve the throughput of the method, this was transferred to LC mass spectrometry, allowing the analysis of a molecule every 3 mins. The developed method was found to be fast, reliable, accurate, easily automatable and simple to set up. Finally, the analytical column’s being industrially manufactured and commercially available offers broad applicability.

Low cross-linked terpenes-based porous polymers with reduced content of divinylbenzene: synthesis, physicochemical properties and sorption abilities

The low cross-linked porous polymers were prepared using terpene compounds (citral, limonene and pinene) and divinylbenzene with a suspension method. The prepared materials were characterized by: ATR-FTIR, low temperature nitrogen adsorption–desorption, TGA, swelling ratio and solid phase extraction (SPE) experiments. ATR-FTIR verified the chemical structures of the polymers. All the materials had developed internal structure with SBET in the range of 45–190 m2/g and high thermal stability. Sorption properties of the terpene-based polymers were tested for phenolic compounds (phenol, 2-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol) and popular non-steroidal anti-inflammatory drugs (aspirin, paracetamol and ibuprofen) and an antibiotic (ampicillin) with a dynamic solid phase extraction (SPE) method. The recoveries of 2,4-dichlorophenol and 2,4,6-trichlorophenol remained at a level 80–100% for all new materials even for 10–13 concentration cycles. Very high recoveries (70–100%) were also obtained for ibuprofen and aspirin from the citral- and limonene-based polymers using one-component solutions. However, when using ternary component solutions, the maximum recoveries of ibuprofen reached 70%. Paracetamol recoveries did not exceed 20%, while these for ampicillin ranged from 40 to 80%. The performed studies have proven that the process is affected by both chemical nature of adsorbents and adsorbates. Especially in the case of multicomponent solutions, the acid—base balance of solutes in the solution and on the polymer—solution interface should be taken into account as an important factor determining obtained recoveries.

The influence of substituting dietary peptide-bound with free amino acids on nitrogen metabolism and acid-base balance of broiler chickens depends on asparagine and glutamine supply.

Reducing dietary crude protein (CP) concentration while maintaining adequate amino acid (AA) supply by free AA inclusion can contribute to attenuate the negative environmental effects of animal farming. This study investigated upper limits of dietary free AA inclusions without undesirable effects including the dependence on asparagine (Asn) and glutamine (Gln) supply. Ten broilers were allocated to sixty-three metabolism units each and offered nine experimental diets from day (d) 7-21 (n 7). One diet (167 g CP/kg) contained 80 g soya protein isolate (SPI)/kg. In the other diets, 25, 50, 75 and 100 % of the digestible AA from SPI were substituted with free AA. Digestible Asn+aspartic acid (Asp) and Gln+glutamic acid (Glu) were substituted with Asp/Glu or 50/50 mixes of Asp/Asn and Glu/Gln, respectively. Total excreta were collected from d 11-14 and from d 18-21. Growth and nitrogen accretion were unaffected by 25 and 50 % substitution without and with free Asn/Gln, respectively, but decreased at higher substitution (P ≤ 0·024). Circulating concentrations of Asp, Glu and Gln were unaffected by treatment, while Asn decreased at substitution higher than 50 % when Asn/Gln were not provided (P ≤ 0·005). Blood gas analysis on d 21 indicated a compensated metabolic acidosis at substitution higher than 50 and 75 % without and with free Asn/Gln, respectively (P ≤ 0·017). Results suggest that adding Asn/Gln increased an upper limit for proportion of dietary free AA from 10 to 19 % of dietary CP and enabled higher free AA inclusion without affecting the acid-base balance.

Renal Tubular Acidosis: Recognition and Treatment Strategies

Renal tubular acidosis (RTA) is a group of kidney disorders characterized by impaired renal acidification, leading to disturbances in acid-base balance. This review article provides a comprehensive overview of RTA, including its epidemiology, pathophysiology, clinical presentation, and diagnosis. Three main types of RTA are discussed: distal RTA (Type 1), proximal RTA (Type 2), and hyperkalemic RTA (Type 4). Each type’s underlying causes and mechanisms are explored, highlighting the importance of accurate diagnosis for appropriate management. Diagnostic approaches involving clinical evaluation, laboratory tests, and specialized renal function studies are described in detail. The treatment strategies for each type of RTA are outlined, emphasizing the importance of correcting the acid-base imbalance and managing associated electrolyte abnormalities. Lifestyle modifications and pharmacological interventions are discussed, including alkali supplementation and potassium regulation. Finally, the need for further research and prospective studies to enhance our understanding of RTA and improve therapeutic interventions is emphasized. Advancements in diagnosis

Two‐ and Three‐Dimensional Strategies for Determining Consecutive Acidity Constants of Ciprofloxacin and Enrofloxacin Using Fluorescent Excitation‐Emission Measurements

AbstractMultidimensional analysis is getting more popular by the day thanks to technical improvements of analytical instruments and development of chemometric methods. Here, we describe the application of two different chemometric methods to the analysis of three‐dimensional spectrofluorimetric dataset for green determination of dissociation constants of ciprofloxacin and enrofloxacin with minimal use of consumables. Three‐dimensional spectrofluorimetric datasets of both drugs were obtained by recording excitation‐emission matrices of only six sample solutions having different pH values. Parallel factor analysis (PARAFAC) and multivariate curve resolution (MCR) methods with the use of three components were used to decompose three‐dimensional excitation‐emission‐pH arrays. The number of components support the presence of two pKa values. The individual profiles of H2A, HA− and A2− species in excitation, emission and pH modes were obtained by the application of PARAFAC and MCR. The intersection points in the pH modes were used to predict pKa values. pKa1 and pKa2 of ciprofloxacin was reported as 6.35, 9.15 and 6.42, 9.40 by PARAFAC and MCR‐ALS, respectively. For enrofloxacin, consecutive pKa values were predicted as 6.11 and 9.06 by PARAFAC and 6.10 and 9.10 by MCR. A detailed comparison to literature was done for the estimated pKa values.

Acute kidney injury in the critical care setting.

Acute kidney injury is a sudden reduction in renal function which impairs the kidneys' ability to maintain fluid, electrolyte and acid-base balance. The syndrome often develops secondary to severe illness and is associated with a significant increase in morbidity and mortality rate in critically ill patients. This article gives an overview of the pathophysiology and aetiology of acute kidney injury, as well as the associated complications and clinical diagnostic signs. The authors also describe some common causes of the syndrome in critically ill patients, specifically sepsis, liver failure and cardiac failure, and discuss patient management in the critical care setting, with a focus on haemodynamic support and continuous renal replacement therapy.

Postoperative analgosedation with dexmedetomidine in combination with paracetamol in pediatric cardiac surgery

BACKGROUND: Although the principles of postoperative multimodal analgesia have been discussed in several articles, this issue remains insufficiently studied in pediatric cardiac surgery.
 AIM: To increase the effectiveness of postoperative analgosedation in children after heart surgery by combining intravenous dexmedetomidine and paracetamol.
 MATERIALS AND METHODS: Prospective, nonrandomized, controlled study (n = 65, 24 yr). Elective heart surgeries were performed in children with congenital heart defects, such as ventricular and/or interatrial septal defect and tetralogy of Fallot, under cardiopulmonary bypass and general anesthesia. Patients were divided into two groups according to the type of postoperative analgesia: group 1, main (n = 35): 30 min after surgery, infusion of dexmedetomidine with a loading dose of 1.0 g/kg/h or 10 min, then infusion of 0.8 g/kg/h during the day against the background of planned analgesia with paracetamol (15 mg/kg, intravenously) 2 h after surgery and then every 8 h during the day; group 2, comparisons (n = 30), 0.3 mg/kg morphine, intramuscularly. The effectiveness of postoperative analgosedation in children was analyzed using the Richmond scale and FLACC + hemodynamics, acid-base balance, blood gases, cortisol, glucose, and blood lactate.
 RESULTS: Sufficient stabilization of the main hemodynamics and respiratory indicators confirmed the adequacy of postoperative analgosedation in group 1 patients. There was a 14% drop in heart rate, specific peripheral resistance, and mean arterial pressure. There was no respiratory depression observed, and the decrease in blood pressure and heart rate was hemodynamically modest. Postoperative stability of blood lactate, glucose, and cortisol levels demonstrated the absence of major metabolic diseases and emotional and physical stress in the main group of children. The transfer of 74.3% of the first group's patients to the specialized department 42.3 5.5 h after the procedure decreased costs and strain on the intensive care unit staff.
 CONCLUSIONS: Dexmedetomidine combined with paracetamol provides an adequate level of sedation, suppresses extubation irritations, prevents psychomotor agitation, and provides sufficient analgesia.

Closed-form expressions for monoprotic weak acid aqueous solutions

A general closed-form expression for {[textrm{H}_{3}textrm{O}^+]} of solutions of a weak acid and a weak acid buffer, as well as their titration with a strong base, has been obtained and mathematically analyzed with the aid of computer algebra systems. This expression is used to evaluate, without the use of numerical approximations, the precision and accuracy of different approximations commonly employed in general chemistry and chemical analysis courses. The closed-form expression for {{[textrm{H}_{3}textrm{O}^+]}} of a buffer solution is used to obtain an analytical expression for the pH stability when a strong base is added. Finally, it is shown that the {[textrm{H}_{3}textrm{O}^+]} expressions for all the systems under study can be obtained from a general closed-form expression in terms of an effective weak acid constant and an effective acid concentration. The formulas found in this work do not display numerical rounding errors and do not require the use of numerical or graphical methods for their evaluation.Graphical abstractGraphical TOC: A closed-form expression for the weak acid and weak acid buffersolutions and their titrations with a strong base

Real-time influence of intracellular acidification and Na+ /H+ exchanger inhibition on in-cell pyruvate metabolism in the perfused mouse heart: A 31 P-NMR and hyperpolarized 13 C-NMR study.

Disruption of acid-base balance is linked to various diseases and conditions. In the heart, intracellular acidification is associated with heart failure, maladaptive cardiac hypertrophy, and myocardial ischemia. Previously, we have reported that the ratio of the in-cell lactate dehydrogenase (LDH) to pyruvate dehydrogenase (PDH) activities is correlated with cardiac pH. To further characterize the basis for this correlation, these in-cell activities were investigated under induced intracellular acidification without and with Na+ /H+ exchanger (NHE1) inhibition by zoniporide. Male mouse hearts (n= 30) were isolated and perfused retrogradely. Intracellular acidification was performed in two ways: (1) with the NH4 Cl prepulse methodology; and (2) by combining the NH4 Cl prepulse with zoniporide. 31 P NMR spectroscopy was used to determine the intracellular cardiac pH and to quantify the adenosine triphosphate and phosphocreatine content. Hyperpolarized [1-13 C]pyruvate was obtained using dissolution dynamic nuclear polarization. 13 C NMR spectroscopy was used to monitor hyperpolarized [1-13 C]pyruvate metabolism and determine enzyme activities in real time at a temporal resolution of a few seconds using the product-selective saturating excitation approach. The intracellular acidification induced by the NH4 Cl prepulse led to reduced LDH and PDH activities (-16% and -39%, respectively). This finding is in line with previous evidence of reduced myocardial contraction and therefore reduced metabolic activity upon intracellular acidification. Concomitantly, the LDH/PDH activity ratio increased with the reduction in pH, as previously reported. Combining the NH4 Cl prepulse with zoniporide led to a greater reduction in LDH activity (-29%) and to increased PDH activity (+40%). These changes resulted in a surprising decrease in the LDH/PDH ratio, as opposed to previous predictions. Zoniporide alone (without intracellular acidification) did not change these enzyme activities. A possible explanation for the enzymatic changes observed during the combination of the NH4 Cl prepulse and NHE1 inhibition may be related to mitochondrial NHE1 inhibition, which likely negates the mitochondrial matrix acidification. This effect, combined with the increased acidity in the cytosol, would result in an enhanced H+ gradient across the mitochondrial membrane and a temporarily higher pyruvate transport into the mitochondria, thereby increasing the PDH activity at the expense of the cytosolic LDH activity. These findings demonstrate the complexity of in-cell cardiac metabolism and its dependence on intracellular acidification. This study demonstrates the capabilities and limitations of hyperpolarized [1-13 C]pyruvate in the characterization of intracellular acidification as regards cardiac pathologies.

Hematomyelia associated with coronavirus disease 2019: A rare case report.

Coronavirus disease 2019 (COVID-19) can damage the central nervous system. Although there have been reports of cerebral hemorrhage and infarction caused by COVID-19, hematomyelia due to COVID-19 has never been reported. A 40-year-old male was admitted to the hospital with positive nucleic acid detection for COVID-19 after experiencing fever for 2 weeks, urinary retention, fecal retention, and pain in both lower extremities for a week. The patient diagnosis was established using thoracic and lumbar magnetic resonance imaging (MRI). Contrast-enhanced thoracic and lumbar MRI revealed subdural (dorsal predominant) short T1 and slightly long T2 bands in the T12-S2 infundibular canal in the scan field, and the subdural hematoma was yet to be distinguished from other diseases. Spinal cord edema was observed in the left vertebral plate and facet joint of the T11 vertebral body, indicative of inflammation. The cerebrospinal fluid (CSF) was positive for COVID-19 nucleic acid. Antiinfection, immunomodulation, correction of acid-base balance and electrolyte disorders, improvement of circulation, nerve nutrition, and other symptomatic supportive treatments were administered to the patient. The patient symptoms significantly improved after 4 weeks of anti-infection and immunomodulatory therapy. Repeat thoracolumbar MRI revealed absorption of the spinal cord hematoma, and the patient was discharged from the hospital. To date, COVID-19-related hematomyelia has not been reported and anti-infective and immunomodulatory therapies may be effective. COVID-19 not only easily leads to brain injury but can also cause spinal cord injury and even spinal cord hemorrhage. When patients with COVID-19 experience symptoms and signs of spinal cord injury, spinal cord injury and bleeding caused by COVID-19 should be considered, and MRI and lumbar puncture should be performed as soon as possible to make a clear diagnosis.

An immunohistochemical study of the vasculature and stem cells and carbonic anhydrase IV in the ducts of irradiated and normal human submandibular salivary glands

ABSTRACT Therapeutic irradiation for cancers of the head and neck causes serious and irreversible damage to the salivary glands; the resulting adverse effects on salivary quality and quantity produce detrimental effects on teeth and oral mucosa. The salivary effects have been related mostly to loss of serous acini; damage to the ducts is relatively minor. Other radiation effects include fibrosis, adiposis and vascular damage. Stem cells in the salivary gland ducts have the potential to generate acinar cells in vitro and in vivo. I investigated the ducts and vasculature in irradiated and normal human submandibular glands using immunohistochemical localization of biomarkers of stem cells, duct function and blood vessels. Stem cell markers CK5 and Sca-1 labeled the cytoplasm of the basal and intercalated duct cells and all duct cells, respectively, in both normal and irradiated glands. CA IV, which participates in regulating salivary electrolytes and acid-base balance, labeled the cytoplasm of all ducts. CD34 labeling demonstrated more extensive vasculature in the irradiated glands than in the normal glands. My findings suggest that duct stem cells and at least one duct function persisted, and the vasculature was greater, despite moderate fibrosis, in the irradiated gland.

The Surface acidity of freshly synthesized microplastics particles in simple electrolyte

The surface chemistry of sub-micron microplastics (MP) particles, specifically, the pH-dependent surface charge (or surface acidity), plays a role on the transport, transformation, and effect of contaminants in the aquatic environment. Little is known on the origin of surface charge and the quantification of surface acidity of MP. In this study, the surface charge of submicron particles of six major polymers, including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), was characterized in inert electrolytes, namely, NaClO4, NaCl, and NaNO3 for the elucidation of surface acidity. IR absorbance revealed that oxygen-rich functional groups were introduced during the resynthesis of MP particles, whose surface chemical structure consists of three main functional groups, i.e., carboxylic/ester, ether/alcohol, and aliphatic. Results show clearly that the zeta potential of MP particles was negatively charged in simple electrolytes at pH greater than ca. 2.0. Hydroxide ions adsorption on the non-polar aliphatic sites, and deprotonation of surface hydroxy group on the polar carboxylic/ester and ether/alcohol sites, contributed to the negative charges on MP surface. The surface acidity of selected MP particles was established in terms of acid strength (intrinsic acidity constants) and capacity (total surface site concentration) for the three distinct surface sites. Results also show the surface acid site density increases with hydration/hydrolysis time with rate constants of the polar surface sites, i.e., carboxylic/ester and ether/alcohol being 2.3 times greater than that of the non-polar aliphatic group.

DECOMPOSITION MECHANISM AND DISSOCIATION CONSTANTS OF BICARBONATE IONS

Using carbonic acid to explain pH changes in aqueous solutions is invalid due to its undetectability under normal temperature and pressure conditions. Instead, two reversible reactions involving the decomposition of HCO3- ions into OH- and CO2 or H+ and CO32- should be employed. The second reaction (H-mechanism) is well known as the basis for the second dissociation constant of “carbonic acid”. For the first reaction (OH-mechanism), the formula has been derived from the first imaginary constant of the same acid. That is, the researchers experimentally determined the proposed constant based on the results of pH value, CO2 and HCO3- concentrations, but calculated the imaginary constant from these values. The pH increase observed following filtration on the cationic resin in Na+ form is attributed to the weakened HCO3- decomposition via the H-mechanism, resulting in decreased H+ and CO32- concentrations. A significant decrease in Ca2+ concentration (from 5.0 to 0.05 mmol/dm3) is the main reason for the observed phenomenon, as it leads to a decrease in the driving force of calcium carbonate formation. The mechanism of bicarbonate ions decomposition based on two reactions has been confirmed experimentally. An increase in the pH of the mixture of CaCl2 and NaHCO3 solutions (both with the same pH and concentration) indicates the H-mechanism, while a decrease in the pH indicates the OH-mechanism decomposition of bicarbonate ions. The pH value at which the pH does not change indicates a change in the decomposition mechanism. The change in the HCO3- dissociation mechanism depends on hardness and alkalinity, and the pH of this change decreases from softened water (pH 8.30) to seawater (pH 7.5).