Mechanistic Investigation into Chemiluminescence from 1,4-Benzoquinone.

Tetrahalogen-1,4-benzoquinone (THBQ) represents a category of H2O2-dependent substrates for chemiluminescence (CL), including tetrafluoro-, tetrachloro-, tetrabromo-, and tetraiodo-1,4-benzoquinone (TFBQ, TCBQ, TBBQ, and TIBQ). A deep understanding of the CL mechanism of THBQ is essential for all H2O2-dependent CL and even some bioluminescence. This article systematically investigates the CL process of THBQ by density functional theory and multireference state theory. The theoretical results confirm the generality of the CL mechanism previously proposed in studies on TCBQ and TBBQ. The dissociation steps producing the emitter of light from dihalogenquinone dioxetane (DHD) and its anion (DHD-), formed by the oxidation of THBQ, were carefully considered. Findings show that the dissociation of DHD/DHD- follows the entropy trap/gradually reversible charge-transfer-induced luminescence (GRCTIL) mechanisms. The dissociation of DHD- is kinetically more advantageous compared with that of DHD. At the practical experimental pH value, the decrease in the electron-withdrawing inductive effect from F to I substituents results in the decrease in the proportions of easily dissociated DHD-, and the increase in the heavy-atom effect from F to I substituents leads to the increase in the phosphorescence emission. These combined factors successively decrease the CL intensity from TFBQ to TCBQ, TBBQ, and TIBQ. The conclusions are verified by the previous experiments on TCBQ and TBBQ, and they are expected to be confirmed by future experiments on TFBQ and TIBQ.

Molecular mechanism of the metal-independent production of hydroxyl radicals by thiourea dioxide and H2O2.

It is well-known that highly reactive hydroxyl radicals (HO•) can be produced by the classic Fenton system and our recently discovered haloquinone/H2O2 system, but rarely from thiol-derivatives. Here, we found, unexpectedly, that HO• can be generated from H2O2 and thiourea dioxide (TUO2), a widely used and environmentally friendly bleaching agent. A carbon-centered radical and sulfite were detected and identified as the transient intermediates, and urea and sulfate as the final products, with the complementary application of electron spin-trapping, oxygen-18 isotope labeling coupled with HPLC/MS analysis. Density functional theory calculations were conducted to further elucidate the detailed pathways for HO• production. Taken together, we proposed that the molecular mechanism for HO• generation by TUO2/H2O2: TUO2 tautomerizes from sulfinic acid into ketone isomer (TUO2-K) through proton transfer, then a nucleophilic addition of H2O2 on the S atom of TUO2-K, forming a S-hydroperoxide intermediate TUO2-OOH, which dissociates homolytically to produce HO•. Our findings represent the first experimental and computational study on an unprecedented new molecular mechanism of HO• production from simple thiol-derived sulfinic acids, which may have broad chemical, environmental, and biomedical significance for future research on the application of the well-known bleaching agent and its analogs.

Study of the PI3K/Akt/mTOR signaling pathway in vitro and molecular docking analysis of periplocin inhibits cell cycle progression and induces apoptosis in MDA-MB-231.

Breast cancer mainly affects women and is the second leading cause of cancer-related deaths worldwide. Breast cancer affects women aged 15-59. The current study explored periplocin's anticancer activities against breast cancer MDA-MB-231 cells by down-regulating the PI3K/Akt/mTOR pathway. The MTT assay assessed control-treated and periplocin (2.5-50 µM) treated MDA-MB-231 cell viability. ROS accumulation and apoptosis levels in periplocin-treated cells were examined using DAPI, dual staining, and Annexin V-FITC/PI assays. Caspase enzymes were studied using assay kits. Flow cytometry was used to measure cell cycle distributions. Periplocin-treated cells were analyzed using RT-PCR assays and insilico analyses for the expression of PI3K/Akt/mTOR molecules. The periplocin treatment remarkably reduced the viability of the MDA-MB-231 cells, with an IC50 concentration of 7.5 µM. The fluorescent staining assays revealed a substantial increase in ROS levels and apoptotic events in the periplocin-treated cells. The flow cytometry analysis revealed that periplocin triggered apoptosis and arrested the cell cycle in G0/G1 phases. Periplocin increased the caspase-3, -8, and -9 enzyme activities. In MDA-MB-231 cells, Periplocin decreased PI3K/Akt/mTOR activity, and in silico analysis, Periplocin was inhibited by CDK8-Cyclin C interactions. Periplocin has anticancer properties against breast cancer and may be an effective therapeutic agent for treating breast cancer.

Performance evaluation of core genome multilocus sequence typing for genotyping of Mycobacterium tuberculosis strains in China: based on multicenter, population-based collection.

PURPOSE: To evaluate the performance of core genome multilocus sequence typing (cgMLST) for genotyping Mycobacterium tuberculosis (M.tuberculosis) Strains in regions where the lineage 2 strains predominate. METHODS: We compared clustering by whole-genome SNP typing with cgMLST clustering in the analysis of WGS data of 6240 strains from five regions of China. Using both the receiver operating characteristic (ROC) curve and epidemiological investigation to determine the optimal threshold for defining genomic clustering by cgMLST. The performance of cgMLST was evaluated by quantifying the sensitivity, specificity and concordance of clustering between two methods. Logistic regression was used to gauge the impact of strain genetic diversity and lineage on cgMLST clustering. RESULTS: The optimal threshold for cgMLST to define genomic clustering was determined to be ≤ 10 allelic differences between strains. The overall sensitivity and specificity of cgMLST averaged 99.6% and 96.3%, respectively; the concordance of clustering between two methods averaged 97.1%. Concordance was significantly correlated with strain genetic diversity and was 3.99 times (95% CI, 2.94-5.42) higher in regions with high genetic diversity (π > 1.55 × 10-4) compared to regions with low genetic diversity. The difference missed statistical significance, while concordance for lineage 2 strains (96.8%) was less than that for lineage 4 strains (98.3%). CONCLUSION : cgMLST showed a discriminatory power comparable to whole-genome SNP typing and could be used to genotype clinical M.tuberculosis strains in different regions of China. The discriminative power of cgMLST was significantly correlated with strain genetic diversity and was slightly lower with strains from regions with low genetic diversity.

Chemical Mechanism of Fireworm Bioluminescence - A Theoretical Proposition.

Odontosyllis undecimdonta is a marine worm, commonly known as a fireworm, that exhibits bluish-green bioluminescence (BL). The luciferin (L) and oxyluciferin (OL) during fireworm BL have been experimentally identified in vitro. The L and OL are the respective starting point and ending point of a series of complicated chemical reactions in the BL. However, the chemical mechanism of the fireworm BL remains largely unknown. Before the experiments provided strong evidence for the mechanism, based on our previously successful studies on several bioluminescent systems, we theoretically proposed the chemical mechanism of the fireworm BL in this article. By means of the spin-flip and time-dependent density functional calculations, we clearly described the complete process from L to OL: under the catalysis of luciferase, L undergoes deprotonation and reacts with 3O2 to form a dioxetanone anion via the single-electron transfer mechanism; the dioxetanone anion decomposes into the OL at the first singlet excited state (S1) by the gradually reversible charge-transfer-induced luminescence mechanism; and the S1-OL emits light and deexcites to OL in the ground state.

The landscape of N6-methyladenosine modification patterns and altered transcript profiles in the cardiac-specific deletion of natriuretic peptide receptor A.

The atrial natriuretic peptide (ANP) and the brain natriuretic peptide (BNP) are critical biological makers and regulators of cardiac functions. Our previous results show that NPRA (natriuretic peptide receptor A)-deficient mice have distinct metabolic patterns and expression profiles compared with the control. Still, the molecular mechanism that could account for this observation remains to be elucidated. Here, methylation alterations were detected by mazF-digestion, and differentially expressed genes of transcriptomes were detected by a Genome Oligo Microarray using the myocardium from NPRA-deficient (NPRA-/-) mice and wild-type (NPRA+/+) mice as the control. Comprehensive analysis of m6A methylation data gave an altered landscape of m6A modification patterns and altered transcript profiles in cardiac-specific NPRA-deficient mice. The m6A "reader" igf2bp3 showed a clear trend of increase, suggesting a function in altered methylation and expression in cardiac-specific NPRA-deficient mice. Intriguingly, differentially m6A-methylated genes were enriched in the metabolic process and insulin resistance pathway, suggesting a regulatory role in cardiac metabolism of m6A modification regulated by NPRA. Notably, it was confirmed that the pyruvate dehydrogenase kinase 4 (Pdk4) gene upregulated the gene expression and the hypermethylation level simultaneously, which may be the key factor for the cardiac metabolic imbalance and insulin resistance caused by natriuretic peptide signal resistance. Taken together, cardiac metabolism might be regulated by natriuretic peptide signaling, with decreased m6A methylation and a decrease of Pdk4.

Mechanistic Investigation of H2 O2 -dependent Chemiluminescence from Tetrabromo-1,4-Benzoquinone.

As a H2 O2 -dependent bioluminescent substrate, tetrabromo-1,4-benzoquinone (TBBQ) was first isolated from acorn worm. The mechanism of chemiluminescence (CL) corresponding to the bioluminescence (BL) of acorn worm is largely unknown, let alone the mechanism of BL. In this article, we firstly studied the chemical and physical processes, and mechanism of H2 O2 -dependent CL from TBBQ by theoretical and experimental methods. The research results indicate: the CL process is initiated by a nucleophilic substitution reaction, which leads to the formation of an anionic dioxetane through five consecutive reactions; the anionic dioxetane decomposes to the first singlet excited state (S1 ) via a conical interaction of the potential energy surfaces (PESs) between the ground (S0 ) and S1 state; the anionic S1 -state changes to its neutral form by a proton transfer from the solvent and this neutral product is assigned as the actual luminophore. Moreover, the experimental detection of CL, . OH and the identifications of 2,3-dibromo maleic acid and 2-bromo malonic acid as the major final products provide direct evidence of the theoretically suggested mechanism. Finally, this study proves that the activity of the H2 O2 -dependent CL from TBBQ is significantly lower than the one from tetrachloro-1,4-benzoquinone (TCBQ), which is caused by the weaker electron withdrawing effect and the stronger heavy atomic effect of bromine.

[The study of hypertonic saline and hydroxyethyl starch treating severe sepsis].

OBJECTIVE: To evaluate the effect of 7.5% hypertonic saline (HS) and 6% hydroxyethyl starch (HES) 130/0.4 on early fluid resuscitation for severe sepsis. METHODS: Prospective randomized control trial was carried out in intensive care unit (ICU) of the Affiliated Hospital of Jianghan University. One hundred and thirty five patients with severe sepsis were randomly divided into three groups, each group consisted of 45 patients. Patients in HS+HES group received lactated Ringer solution following 4 ml/kg of 7.5% HS and 6% HES 130/0.4 500 ml, those in HES group received lactated Ringer solution following 6% HES 130/0.4 500 ml, and those in the lactated Ringer group (RL group) received lactated Ringer solution only.Mean arterial pressure (MAP), oxygenation index (PaO2/FiO2),arterial lactate (Lac),lactate clearance rate, acute physiology and chronic health evaluation II(APACHEII) score,fluid infusion volume, urine output as well as incidence of multiple organ dysfunction syndrome (MODS), and mortality were compared among three groups at 6 hours and 24 hours after ICU admission. RESULTS: At 6 hours after ICU admission,MAP[mm Hg (1 mm Hg=0.133 kPa): 68.7 ± 3.0], PaO2/FiO2(mm Hg: 262.2 ± 17.4), lactate clearance rate [(21 ± 4)%] in HS+HES group were significantly higher than those in HES group [MAP: 63.8 ± 3.5,PaO(2)/FiO(2): 252.0 ± 21.2, lactate clearance rate: (11 ± 2)%] and RL group [MAP: 62.6 ± 3.6, PaO2/FiO2:248.4 ± 17.0,lactate clearance rate: (9 ± 1)%, all P <0.01]. Arterial Lac in HS+HES group (mmol/L: 3.5 ± 0.7) was significantly lower than that in HES group (4.1 ± 0.7) and RL group (4.0 ± 0.7, both P <0.01). There was no significant difference in APACHE II score between HS+HES group (13.2 ± 1.9) and HES group (14.0 ± 1.6), and the APACHEII score in HS+HES group was significantly lower than that in RL group (15.2 ± 1.7, P <0.01). At 24 hours after ICU admission, PaO2/FiO2 (mm Hg: 303.3 ± 17.3) was significantly higher in HS+HES group than that in HES group (282.9 ± 21.1) and RL group (268.9 ± 15.2, both P <0.01). There was no significant difference in MAP, arterial Lac, lactate clearance rate and APACHEII score among three groups. At 6 hours and 24 hours after ICU admission, fluid infusion volume in HS+HES group (ml, 6 hours: 1 877.8 ± 215.2, 24 hours: 5 475.6 ± 208.8) was markedly less than that in HES group (6 hours: 2 505.6 ± 276.2, 24 hours: 6 383.3 ± 287.4) and RL group (6 hours: 3 496.7 ± 325.5,24 hours: 7 439.6 ± 229.6), yet urine output in HS+HES group (ml, 6 hours: 294.2 ± 36.9, 24 hours : 2 793.8 ± 37.1) was significantly higher than that in HES group (6 hours: 248.9 ± 25.3, 24 hours : 2 248.9 ± 25.3) and RL group (6 hours: 178.9 ± 14.8, 24 hours: 2 000.4 ± 147.0, all P <0.01). The incidence of MODS in HS+HES group (6.7%) was statistically lower than that in RL group (28.9%, P <0.05), while no obvious difference was found between HS+HES group and HES group (17.8%, P >0.05). There was no significant difference in mortality among three groups (HS+HES group: 2.2%, HES group: 4.4%, RL group: 8.9%, all P >0.05). CONCLUSION: 7.5%HS and 6%HES 130/0.4 could improve the effect of early fluid resuscitation on severe sepsis, and it could lower the incidence of MODS.

[Value of microalbuminuria in fluid balance after abdominal surgery].

OBJECTIVE: To evaluate the relationship among the microalbuminuria, surgical stress and postoperative fluid balance after abdominal surgery. METHODS: A total of 191 patients undergoing an elective abdominal operation were studied. According to the extent of operative trauma, all patients were divided into 4 groups. GroupI: laparoscopic cholecystectomy (n=64); Group II: laparotomy of cholecyst and biliary tract (n=36); Group III: radical surgery of colorectal cancer (n=43); Group IV: distal subtotal gastrectomy (D2) or total gastectomy (D3) or pancreaticoduodenectomy (n=48). The operative severities were predicated by surgical stress score (SSS). Urine albumin-creatinine ratio (ACR) was measured at both pre- and post-operation. The levels of ACR were compared by ANOVA among these 4 groups. The correlation of ACR and SSS was analyzed. In Groups III and IV, body weight was measured by weight-bed simultaneously. The correlation of variation of ACR at 0 and 6 hours post-operation (ΔACR) and the volume of positive fluid balance in the first 24 hour post-operation were studied. We also compared the varied durations of ACR levels returning to normal or the pre-operative level and body weight reaching peak values. RESULTS: The levels of ACR increased in all groups. The level of ACR was the highest in Group IV and the lowest in Group I, significantly different from the levels of group II and III. There was a significant positive correlation between the increase in ACR and the severity of surgical trauma as measured by SSS. A positive correlation was observed between the volume of positive fluid balance in the first 24 hour post-operation and ΔACR at 0 and 6 hours post-operation. The varied duration of ACR levels returning normal or the pre-operative level was earlier than that of reaching the peak values. CONCLUSION: ACR has a positive correlation with the extent of surgical stress and volume of positive fluid balance. The fact that the ACR comes earlier than the change of body weight indicates that the change of ACR is a more sensitive and simpler parameter than body weight to predict the onset of negative fluid balance.

[Application of B type natriuretic peptide in fluid therapy after major abdominal operations].

OBJECTIVE: To evaluate the values of serum level of B type natriuretic peptide level (BNP) in the prediction of fluid overloading after major abdominal operations. METHODS: The levels of BNP were dynamically monitored in 105 patients during peri-operative period from February 2009 to November 2010. Then comparisons were made with age and the volume of positive fluid balance. RESULTS: A post-operative elevation of BNP was observed in all cases. Among them, the peak level of BNP exceeded 100 ng/L in 32 patients while a normal peak level of BNP was found in 73 patients. Congestive heart failure (CHF) was diagnosed in 5 patients. At every single time point, the volume of positive fluid balance showed no significant difference among the peak level of BNP < 100 ng/L, ≥ 100 ng/L and CHF patients (all P > 0.05). In the group of peak level of BNP ≥ 100 ng/L, the patients received post-operative diuretic and the urine volume increased significantly [(280 ± 55) ml/h vs (82 ± 22) ml/h, P < 0.05]. However, in the group of the peak level of BNP < 100 ng/L, the urine volume showed no difference after dosing of diuretic [(95 ± 18) ml/h vs (89 ± 24) ml/h, P > 0.05]. Single variance analysis showed that the elevated level of BNP was associated with age and concurrent cardiopulmonary diseases (R = 0.87, P = 0.006) but not with the volume of positive fluid balance (R = 0.43, P = 0.080). And multiple variance analysis showed the similar results (R = 0.59, P = 0.020, R = 0.38, P = 0.120). In all cases, the levels of BNP peaked at 12 hours post-operation. However, body weight and the volume of positive fluid balance peaked at 18 - 24 hours post-operation. CONCLUSION: The post-operative level of BNP is associated with age. And a highly elevated level of BNP may predict the occurrence of fluid overloading. An early peak of BNP value may be used as a cut-off point of positive and negative fluid balances.

Effects of 7.5% hypertonic saline on fluid balance after radical surgery for gastrointestinal carcinoma.

AIM: To investigate the effects of 7.5% hypertonic saline on positive fluid balance and negative fluid balance, after radical surgery for gastrointestinal carcinoma. METHODS: Fifty-two patients with gastrointestinal carcinoma undergoing radical surgery were studied. The patients were assigned to receive either Ringer lactate solution following 4 mL/kg of 7.5% hypertonic saline (the experimental group, n = 26) or Ringer lactate solution (the control group, n = 26) during the early postoperative period in SICU. Fluid infusion volumes, urine outputs, fluid balance, body weight change, PaO2/FiO2 ratio, anal exhaust time as well as the incidence of complication and mortality were compared between the two groups. RESULTS: Urine outputs on the operative day and the first postoperative day in experimental group were significantly more than in control group (P<0.000001, P = 0.000114). Fluid infusion volumes on the operative day and the first postoperative day were significantly less in experimental group than in control group (P = 0.000042, P = 0.000415). The volumes of the positive fluid balance on the operative day and during the first 48 h after surgery, in experimental group, were significantly less than in control group (P<0.000001). Body weight gain post-surgery was significantly lower in experimental group than in control group (P<0.000001). The body weight fall in experimental group occurred earlier than in control group (P<0.000001). PaO2/FiO2 ratio after surgery was higher in experimental group than in control group (P = 0.000111). The postoperative anal exhaust time in experimental group was earlier than in control group (P = 0.000006). The overall incidence of complications and the incidence of pulmonary infection were lower in experimental group than in control group (P = 0.0175, P = 0.0374). CONCLUSION: 7.5% hypertonic saline has an intense diuretic effect and causes mobilization of the retained fluid, which could reduce fluid infusion volumes and positive fluid balance after radical surgery for gastrointestinal carcinoma, as well as, accelerate the early appearance of negative fluid balance after the surgery, improve the oxygen diffusing capacity of the patients' alveoli, and lower the overall incidence of complications and pulmonary infection after the surgery.