Calibration of titration calorimeters is an ongoing problem, particularly with calorimeters with reaction vessel volumes < 10 mL in which an electrical calibration heater is positioned outside the calorimetric vessel. Consequently, a chemical reaction with a known enthalpy change must be used to accurately calibrate these calorimeters. This work proposes the use of standard solutions of potassium acid phthalate (KHP) titrated into solutions of excess sodium hydroxide (NaOH) or excess tris(hydroxymethyl)aminomethane (TRIS) as standard reactions to determine the collective accuracy of the relevant variables in a determination of the molar enthalpy change for a reaction. KHP is readily available in high purity, weighable for easy preparation of solutions with accurately known concentrations, stable in solution, not compromised by side reactions with common contaminants such as atmospheric CO2, and non-corrosive to materials used in calorimeter construction. Molar enthalpy changes for these reactions were calculated from 0 to 60 °C from reliable literature data for the pKa of KHP, the molar enthalpy change for protonation of TRIS, and the molar enthalpy change for ionization of water. The feasibility of using these reactions as enthalpic standards was tested in several calorimeters; a 50 mL CSC 4300, a 185 μL NanoITC, a 1.4 mL VP-ITC, and a TAM III with 1 mL reaction vessels. The results from the 50 mL CSC 4300, which was accurately calibrated with an electric heater, verified the accuracy of the calculated standard values for the molar enthalpy changes of the proposed reactions.

Functional nucleic acids (FNAs) have attracted a lot of attention for the rapid detection of metal ions. Cr3+ is one of the major heavy metal ions in natural waters. Due to the slow ligand exchange rate of Cr3+, the FNA-based Cr3+ sensors require long assay times, limiting the on-site applications. In this study, we report that the good\'s buffers containing amino and polyhydroxy groups greatly increase the ligand exchange rate of Cr3+. Using EDTA as a model coordinate ligand, the Tris buffer (100 mM, pH 7.0) showed the best acceleration effect among the eight buffers. It improved the rate constant ∼20-fold, shorten the half-time 19-fold, and lowered the activation energy ∼70% at 40 °C. The Tris buffer was then applied for sensor based on the Cr3+-binding induced fluorescence quenching of fluorescein (FAM)-labeled and single-stranded DNA (ssDNA), which shortened the assay time from 1 h to 1 min. The Tris buffer also ∼100% enhanced the fluorescence intensity of FAM, achieving the 11.4-fold lower limit of detection (LOD = 6.97 nM, S/N = 3). By the combination use of the Tris buffer and ascorbic acid, the strong interference from Cu2+, Pb2+, and Fe3+ suffered in many previous reported Cr3+ sensors was avoided. The practical application of the sensor for the detection of Cr3+ spiked in the real water samples were demonstrated with high recovery percentages. The Tris buffer could be applied for other metal ions with slow ligand exchange rate (such as V2+, Co3+ and Fe2+) to solve diverse issues such as long assay time and low synthesis yield of metal complexes, without the need of heating treatment.

OBJECTIVE: To study the preemptive analgesic effect of dexketoprofen tromethamine in extraction of impacted teeth.
METHODS: Twenty patients with bilateral mandibular impacted teeth were selected, and were randomly divided into dexketoprofen tromethamine group(experimental group) and placebo group(control group). The pain scores of patients at 0.5, 2, 4, 8, 12, and 24 hours after tooth extraction were counted by numeric rating scale(NRS), and the total dosage of emergent analgesic drugs used in 24 hours was recorded. COX analysis method was used to compare the interval time and the number of cases of first application of emergent analgesic drugs after two operations, and the survival curve was drawn. SPSS 20.0 software package was used for data analysis.
RESULTS: The NRS scores of postoperative pain in the experimental group were significantly lower than those in the control group at 2, 4, 8 and 12 hours after operation (P＜0.05). The dose of emergent analgesics used in the experimental group for 24 h was significantly lower than that in the control group (P＜0.05). Survival curve showed that the interval time between the first application of analgesics in the experimental group was significantly longer than that in the control group(P＜0.05).
CONCLUSIONS: Dexketoprofen tromethamine can achieve obvious analgesic effect within 12 hours, but the analgesic effect is not obvious after 12 hours.

The development of heat-induced antigen retrieval technologies with Tris-EDTA buffer has dramatically improved immunostaining of specific antigens for routine immunohistochemical detection (Krenacs et al., 2010) [1]. However, little evidence exists on whether heat-Induced antigen retrieval utilizing Tris-EDTA buffer can strip western blot (WB) membranes and allow sequential reprobing. Here, we serendipitously discover that ∼95 °C Tris-EDTA buffer with 0.01% Tween 20 could repeatedly strip the Nitrocellulose membranes (NC). After electroblotting, NC blots were soaked into Tris-EDTA stripping buffer (∼95 °C, 10-25min) and we could perform at least five rounds (the following antibodies used: Vinculin, Atg7, Caspase-3, UBA5, JNK and ERK1/2) stripping in sequential chemiluminescent detections. The NC membranes also show clear western signals and background without losing transferred proteins during the reprobing process of WB. Hence, this study report additional new roles of the heat-Induced antigen retrieval Tris-EDTA buffer with 0.01% Tween 20. The method is simpler, more affordable and harmless for the nitrocellulose paper, which will be helpful for effective reprobing in western blotting applications.

A fluorescent biosensor for real-time monitoring the release of Zn2+ in plants was constructed through immobilization of DNAzyme-containing hairpin DNA on nanofertilizer ZnO@Au nanoparticles (ZnO@Au NPs). A specially designed hairpin DNA containing both DNAzyme and its substrate sequence, which was also labeled with 5\'-FAM and 3\'-SH groups, was modified on ZnO@Au NPs through the Au-S bond. The fluorescent signal of FAM was initially quenched by AuNPs. When Zn2+ was released from ZnO@Au NPs, DNAzyme was activated and the substrate sequence in hairpin DNA was cleaved. The restored fluorescent signal in Tris-HCl buffer (pH 6.5) was correlated with the concentration of the released Zn2+. The performance of the biosensor was first demonstrated in the solution. The linear detection range was from 50 nM to 1.5 μM, with a detection limit of 30 nM. The biosensor system can penetrate into maize leaves with ZnO@Au NPs. With the release of Zn2+ in leaves, the restored fluorescence can be imaged by a confocal laser scanning microscope and used for monitoring the release and distribution of Zn2+. This work may provide a novel strategy for tracing and understanding the mechanism of nanofertilizers in organisms.

Objective: To evaluate the efficacy of ketochromate tromethamine and phloroglucinol combination therapy in early expulsion of ureteral calculi after extracorporeal shockwave lithotripsy (ESWL) in patients with distal ureteral clculi. The clinical and follow-up data of 275 patients with lower ureteral calculi who underwent ESWL were collected retrospectively in Civil Aviation General Hospital from January 1st 2021 to June 30th 2021. According to whether adjunctive medication used before ESWL patients were divided into control group and medication group (with ketochromate tromethamine 30 mg and phloroglucinol 80 mg before ESWL). Primary endpoint is the clearance rate of ureteral calculi after ESWL, secondary endpoint are the other outcomes and drug allergy. There were 138 cases in control group [117 were males and mean age (42±13) years]. Meanwhile, there were 137 cases in medication group [118 were males and mean age (42±12) years]. The clearance rate of ureteral calculi at 24 h (67.88% vs 48.55%, P=0.001)、one week (76.64% vs 57.97%, P=0.001) and four weeks (89.05% vs 76.08%, P=0.005)after ESWL in medication group were significant higher than that in control group. There was a significant difference in the VAS score of pain scale after ESWL (1.77±0.80 vs 2.06±1.04, P=0.012) and re-ESWL rate (8.03% vs 17.39%,P=0.02) between two groups, but no difference with gross hematuria in 6 h after ESWL and drug allergy. Conclusions combination use of ketochromate tromethamine and phloroglucinol significantly improve early expulsion of ureteral calculi after ESWL in patients with distal ureteral calculi, with no side effect.
本研究回顾性分析了2021年1—6月在民航总医院泌尿外科实施输尿管下段结石体外碎石的275例患者的临床资料。根据是否应用辅助药物治疗分为对照组和用药组（体外碎石前联合应用酮咯酸氨丁三醇30 mg与间苯三酚80 mg），随访观察两组体外碎石后结石排出率和其他临床结局指标。对照组138例患者，男117例，年龄（42±13）岁；用药组137例患者，男118例，年龄（42±12）岁。两组患者体外碎石后24 h排石率（67.88%比48.55%，P=0.001）、1周排石率（76.64%比57.97%，P=0.001）和4周排石率（89.05%比76.08%，P=0.005）用药组均高于对照组；碎石后疼痛视觉模拟评分（VAS）（1.77±0.80比2.06±1.04，P=0.012）及再次碎石率（8.03%比17.39%，P=0.020）用药组均低于对照组；碎石后6 h内肉眼血尿及药物过敏发生率两组间差异无统计学意义（P>0.05）。证实酮咯酸氨丁三醇与间苯三酚联合辅助治疗可显著提高输尿管下段结石体外碎石术后早期排石率，未见明显不良反应。.

High-resolution membrane protein structures are essential for a fundamental understanding of the molecular basis of diverse cellular processes and for drug discovery. Detergents are widely used to extract membrane-spanning proteins from membranes and maintain them in a functional state for downstream characterization. Due to limited long-term stability of membrane proteins encapsulated in conventional detergents, development of novel agents is required to facilitate membrane protein structural study. In the current study, we designed and synthesized tris(hydroxymethyl)aminomethane linker-bearing triazine-based triglucosides (TTGs) for solubilization and stabilization of membrane proteins. When these glucoside detergents were evaluated for four membrane proteins including two G protein-coupled receptors, a few TTGs including TTG-C10 and TTG-C11 displayed markedly enhanced behaviors toward membrane protein stability relative to two maltoside detergents [DDM (n-dodecyl-β-d-maltoside) and LMNG (lauryl maltose neopentyl glycol)]. This is a notable feature of the TTGs as glucoside detergents tend to be inferior to maltoside detergents at stabilizing membrane proteins. The favorable behavior of the TTGs for membrane protein stability is likely due to the high hydrophobicity of the lipophilic groups, an optimal range of hydrophilic-lipophilic balance, and the absence of cis-trans isomerism.

The electrochemical aptamer-based (E-AB) biosensor usually has a long reaction time when detecting thrombin. This work reports the design of an E-AB biosensor with dual recognition sites to quickly detect thrombin. Specifically, two specific recognition sites of thrombin were used to design three aptamer sequences (TBA-15, TBA-29 and TBA-U), followed by fabrication of corresponding sensors. First, we tested these three types of biosensors in tris buffer solution, and found that the response time of the TBA-U sensor to the same concentration of thrombin was about 2 hours, which is shorter than TBA-15 and TBA-29 sensors. Then, we also did the same test in 50 % diluted serum with 500 nM thrombin. The response time of the TBA-U sensor was about 2 hours, which is still faster than the 3 hours of TBA-15 sensor and the 5.5 hours for TBA-29 sensor. In addition, in terms of dynamic range and specificity, TBA-U has good performance.

BACKGROUND: Loxoprofen tromethamine is a novel structural compound related to loxoprofen. It has been used for the treatment of pain and inflammation. However, the embryo-fetal developmental toxicity (EFDT) of loxoprofen tromethamine has not been evaluated in detail in vivo. This study investigated the EFDT and toxicokinetics of loxoprofen tromethamine in rats.
METHODS: The aim of this study was to investigate the potential reproductive toxicity on embryo-fetal development of loxoprofen tromethamine (0, 1, 3, and 10 mg/kg/day) and sodium cyclophosphamide (CP) (2.8 mg/kg/day) administered by intravenous injection to pregnant rats during gestation days (GDs) 6-15. Pregnant rats were euthanized on GD20. The numbers of live/dead fetuses, resorptions, implantations, and corpora lutea, gravid uterus mass, placenta mass, fetal gender ratios, body weight, and skeletal development were evaluated. In a concomitant toxicokinetic (TK) study (10 pregnant rats per group), plasma TK parameters and the tissue distribution of loxoprofen tromethamine were tested.
RESULTS: On GD20, rats were anesthetized and dissected by caesarean section. The appearance, internal organs, gravid uterus weight, embryo implantation number, and implantation loss rate in maternal rats of each group did not reveal any lesions. In fetuses, there were no significant differences in the fetus weight, embryo resorption number, stillbirth number, or fetal visceral examination in all test groups compared to the negative control group. However, in the high-dose group, the fetuses showed significant differences in the anomalies of the bones compared to the negative control group. The TK study showed that in the dose range of 1-10 mg/kg, the Cmax and AUC(0-t) of loxoprofen tromethamine in animals after the first administration increased proportionally to the dose, showing linear kinetic characteristics; after the last administration, the Cmax and AUC(0-t) increased disproportionately to the dose, showing nonlinear kinetic characteristics. The results of tissue distribution show that loxoprofen tromethamine was mainly distributed in the placenta and lung after the intravenous administration to pregnant rats; the content in the liver was lower and increased sharply in the heart with increasing doses; the content in all tissues was lower than that in the plasma. Loxoprofen tromethamine in fetal tissues and organs was mainly distributed in fetal lungs, liver and heart, and the lowest content was in amniotic fluid.
CONCLUSIONS: In conclusion, the no-observed-adverse-effect level (NOAEL) and lowest-observed-adverse-effect level (LOAEL) of loxoprofen tromethamine were considered to be 1 and 10 mg/kg/day, respectively.

The interaction between di-n-butyl phthalate (DBP) and bovine serum albumin (BSA) in physiological Tris-HCl buffer at pH 7.4 was investigated by fluorescence quenching technique. By analyzing the fluorescence spectrum and intensity, it was observed that the DBP had a strong ability to quench the intrinsic fluorescence of BSA through a static quenching procedure. The binding constants K and the number of binding sites n of DBP with BSA were calculated to be 0.11 × 102 L·mol-1 and 0.52 at 298 K, respectively. The thermodynamic parameters of enthalpy change (ΔH) and entropy change (ΔS) were also calculated to be positive showing that hydrophobic forces might play a major role in the binding of DBP to BSA. The binding process was spontaneous in which Gibbs free energy change (ΔG) was negative. The distance (r) between the donor (BSA) and acceptor (DBP) was calculated to be 2.02 nm based on Forster\'s non-radiative energy transfer theory, which indicated that the energy transfer from BSA to DBP occurs with a high possibility. The synchronous fluorescence, three-dimensional fluorescence, and circular dichroism (CD) spectra showed that the binding of di-n-butyl phthalate to BSA induced conformational changes in BSA. The interaction between DBP and BSA can help researchers better understand the nature of poisons and serve people in the right way with first aid and detoxification.